Uplink Transmission for Early Time Alignment Acquisition

Abstract

A wireless device receives, via a serving cell, one or more radio resource control (RRC) messages comprising configuration parameters of a candidate cell for a layer 1/2 triggered mobility (LTM) procedure. The configuration parameters indicate a transmission power of a synchronization signal block (SSB) transmitted via the candidate cell. The wireless device receives a physical downlink control channel (PDCCH) order comprising a cell indicator indicating the candidate cell, an SSB index indicating the SSB of SSBs of the candidate cell, and a preamble index of a preamble. The wireless device transmits, via a physical random access channel (PRACH) occasion corresponding to the SSB of the candidate cell, the preamble using an uplink transmission power based on a measurement of a pathloss. The pathloss is determined based on the transmission power of the SSB, and a layer 3 filtered reference signal received power (RSRP) of the SSB.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of several of the various embodiments of the present disclosure are described herein with reference to the drawings.

FIG. 1A and FIG. 1B illustrate example mobile communication networks in which embodiments of the present disclosure may be implemented.

FIG. 2A and FIG. 2B respectively illustrate a New Radio (NR) user plane and control plane protocol stack.

FIG. 3 illustrates an example of services provided between protocol layers of the NR user plane protocol stack of FIG. 2A.

FIG. 4A illustrates an example downlink data flow through the NR user plane protocol stack of FIG. 2A.

FIG. 4B illustrates an example format of a MAC subheader in a MAC PDU.

FIG. 5A and FIG. 5B respectively illustrate a mapping between logical channels, transport channels, and physical channels for the downlink and uplink.

FIG. 6 is an example diagram showing RRC state transitions of a UE.

FIG. 7 illustrates an example configuration of an NR frame into which OFDM symbols are grouped.

FIG. 8 illustrates an example configuration of a slot in the time and frequency domain for an NR carrier.

FIG. 9 illustrates an example of bandwidth adaptation using three configured BWPs for an NR carrier.

FIG. 10A illustrates three carrier aggregation configurations with two component carriers.

FIG. 10B illustrates an example of how aggregated cells may be configured into one or more PUCCH groups.

FIG. 11A illustrates an example of an SS/PBCH block structure and location.

FIG. 11B illustrates an example of CSI-RSs that are mapped in the time and frequency domains.

FIG. 12A and FIG. 12B respectively illustrate examples of three downlink and uplink beam management procedures.

FIG. 13A, FIG. 13B, and FIG. 13C respectively illustrate a four-step contention-based random access procedure, a two-step contention-free random access procedure, and another two-step random access procedure.

FIG. 14A illustrates an example of CORESET configurations for a bandwidth part.

FIG. 14B illustrates an example of a CCE-to-REG mapping for DCI transmission on a CORESET and PDCCH processing.

FIG. 15 illustrates an example of a wireless device in communication with a base station.

FIG. 16A, FIG. 16B, FIG. 16C, and FIG. 16D illustrate example structures for uplink and downlink transmission.

FIG. 17A, FIG. 17B, and FIG. 17C show examples of MAC subheaders.

FIG. 18A shows an example of a DL MAC PDU.

FIG. 18B shows an example of an UL MAC PDU.

FIG. 19 shows an example of multiple LCIDs of downlink.

FIG. 20 shows an example of multiple LCIDs of uplink.

FIG. 21A and FIG. 21B show examples of SCell activation/deactivation MAC CE formats.

FIG. 22 shows an example of BWP activation/deactivation on a cell.

FIG. 23 shows examples of a variety of DCI formats.

FIG. 24A shows an example of MIB message.

FIG. 24B shows an example of configuration of CORESET 0.

FIG. 24C shows an example of configuration of search space 0.

FIG. 25 shows an example of SIB1 message.

FIG. 26 shows an example of RRC configurations of a BWP, PDCCH, and a CORESET.

FIG. 27 shows an example of RRC configuration of a search space.

FIG. 28 shows an example of SSB configurations.

FIG. 29 shows an example of SSB transmissions of a base station.

FIG. 30 shows an example of SSB transmissions of a base station.

FIG. 31A and FIG. 31B show example embodiments of multiple TRPs configuration.

FIG. 32 shows an example embodiment of layer 3 based handover procedure.

FIG. 33 shows an example embodiment of RRC message for layer 3 based handover.

FIG. 34 shows an example embodiment of RRC message for layer 3 based handover.

FIG. 35 shows an example embodiment of layer 3 based conditional handover procedure.

FIG. 36 shows an example embodiment of RRC message for layer 3 based conditional handover procedure.

FIG. 37 shows an example embodiment of layer 1/2 triggered mobility.

FIG. 38 shows an example embodiment of inter-cell beam management.

FIG. 39 shows an example embodiment of PCell switching for network energy saving.

FIG. 40A and FIG. 40B show examples of processing times of PCell switching.

FIG. 41 shows an example embodiment of layer 1/2 triggered mobility for PCell switching/changing.

FIG. 42 shows an example embodiment of early TA acquisition for layer 1/2 triggered mobility.

FIG. 43 shows an example embodiment of early TA acquisition for layer 1/2 triggered mobility.

DETAILED DESCRIPTION

In the present disclosure, various embodiments are presented as examples of how the disclosed techniques may be implemented and/or how the disclosed techniques may be practiced in environments and scenarios. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the scope. In fact, after reading the description, it will be apparent to one skilled in the relevant art how to implement alternative embodiments. The present embodiments should not be limited by any of the described exemplary embodiments. The embodiments of the present disclosure will be described with reference to the accompanying drawings. Limitations, features, and/or elements from the disclosed example embodiments may be combined to create further embodiments within the scope of the disclosure. Any figures which highlight the functionality and advantages, are presented for example purposes only. The disclosed architecture is sufficiently flexible and configurable, such that it may be utilized in ways other than that shown. For example, the actions listed in any flowchart may be re-ordered or only optionally used in some embodiments.

Embodiments may be configured to operate as needed. The disclosed mechanism may be performed when certain criteria are met, for example, in a wireless device, a base station, a radio environment, a network, a combination of the above, and/or the like. Example criteria may be based, at least in part, on for example, wireless device or network node configurations, traffic load, initial system set up, packet sizes, traffic characteristics, a combination of the above, and/or the like. When the one or more criteria are met, various example embodiments may be applied. Therefore, it may be possible to implement example embodiments that selectively implement disclosed protocols.

A base station may communicate with a mix of wireless devices. Wireless devices and/or base stations may support multiple technologies, and/or multiple releases of the same technology. Wireless devices may have some specific capability(ies) depending on wireless device category and/or capability(ies). When this disclosure refers to a base station communicating with a plurality of wireless devices, this disclosure may refer to a subset of the total wireless devices in a coverage area. This disclosure may refer to, for example, a plurality of wireless devices of a given LTE or 5G release with a given capability and in a given sector of the base station. The plurality of wireless devices in this disclosure may refer to a selected plurality of wireless devices, and/or a subset of total wireless devices in a coverage area which perform according to disclosed methods, and/or the like. There may be a plurality of base stations or a plurality of wireless devices in a coverage area that may not comply with the disclosed methods, for example, those wireless devices or base stations may perform based on older releases of LTE or 5G technology.

In this disclosure, “a” and “an” and similar phrases are to be interpreted as “at least one” and “one or more.” Similarly, any term that ends with the suffix “(s)” is to be interpreted as “at least one” and “one or more.” In this disclosure, the term “may” is to be interpreted as “may, for example.” In other words, the term “may” is indicative that the phrase following the term “may” is an example of one of a multitude of suitable possibilities that may, or may not, be employed by one or more of the various embodiments. The terms “comprises” and “consists of”, as used herein, enumerate one or more components of the element being described. The term “comprises” is interchangeable with “includes” and does not exclude unenumerated components from being included in the element being described. By contrast, “consists of” provides a complete enumeration of the one or more components of the element being described. The term “based on”, as used herein, should be interpreted as “based at least in part on” rather than, for example, “based solely on”. The term “and/or” as used herein represents any possible combination of enumerated elements. For example, “A, B, and/or C” may represent A; B; C; A and B; A and C; B and C; or A, B, and C.

If A and B are sets and every element of A is an element of B, A is called a subset of B. In this specification, only non-empty sets and subsets are considered. For example, possible subsets of B={cell1, cell2} are: {cell1}, {cell2}, and {cell1, cell2}. The phrase “based on” (or equally “based at least on”) is indicative that the phrase following the term “based on” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “in response to” (or equally “in response at least to”) is indicative that the phrase following the phrase “in response to” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “depending on” (or equally “depending at least to”) is indicative that the phrase following the phrase “depending on” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “employing/using” (or equally “employing/using at least”) is indicative that the phrase following the phrase “employing/using” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments.

The term configured may relate to the capacity of a device whether the device is in an operational or non-operational state. Configured may refer to specific settings in a device that effect the operational characteristics of the device whether the device is in an operational or non-operational state. In other words, the hardware, software, firmware, registers, memory values, and/or the like may be “configured” within a device, whether the device is in an operational or nonoperational state, to provide the device with specific characteristics. Terms such as “a control message to cause in a device” may mean that a control message has parameters that may be used to configure specific characteristics or may be used to implement certain actions in the device, whether the device is in an operational or non-operational state.

In this disclosure, parameters (or equally called, fields, or Information elements: IEs) may comprise one or more information objects, and an information object may comprise one or more other objects. For example, if parameter (IE) N comprises parameter (IE) M, and parameter (IE) M comprises parameter (IE) K, and parameter (IE) K comprises parameter (information element) J. Then, for example, N comprises K, and N comprises J. In an example embodiment, when one or more messages comprise a plurality of parameters, it implies that a parameter in the plurality of parameters is in at least one of the one or more messages, but does not have to be in each of the one or more messages.

Many features presented are described as being optional through the use of “may” or the use of parentheses. For the sake of brevity and legibility, the present disclosure does not explicitly recite each and every permutation that may be obtained by choosing from the set of optional features. The present disclosure is to be interpreted as explicitly disclosing all such permutations. For example, a system described as having three optional features may be embodied in seven ways, namely with just one of the three possible features, with any two of the three possible features or with three of the three possible features.

Many of the elements described in the disclosed embodiments may be implemented as modules. A module is defined here as an element that performs a defined function and has a defined interface to other elements. The modules described in this disclosure may be implemented in hardware, software in combination with hardware, firmware, wetware (e.g. hardware with a biological element) or a combination thereof, which may be behaviorally equivalent. For example, modules may be implemented as a software routine written in a computer language configured to be executed by a hardware machine (such as C, C++, Fortran, Java, Basic, MATLAB or the like) or a modeling/simulation program such as Simulink, Stateflow, GNU Octave, or LabVIEWMathScript. It may be possible to implement modules using physical hardware that incorporates discrete or programmable analog, digital and/or quantum hardware. Examples of programmable hardware comprise: computers, microcontrollers, microprocessors, application-specific integrated circuits (ASICs); field programmable gate arrays (FPGAs); and complex programmable logic devices (CPLDs). Computers, microcontrollers and microprocessors are programmed using languages such as assembly, C, C++ or the like. FPGAs, ASICs and CPLDs are often programmed using hardware description languages (HDL) such as VHSIC hardware description language (VHDL) or Verilog that configure connections between internal hardware modules with lesser functionality on a programmable device. The mentioned technologies are often used in combination to achieve the result of a functional module.

FIG. 1A illustrates an example of a mobile communication network 100 in which embodiments of the present disclosure may be implemented. The mobile communication network 100 may be, for example, a public land mobile network (PLMN) run by a network operator. As illustrated in FIG. 1A, the mobile communication network 100 includes a core network (CN) 102, a radio access network (RAN) 104, and a wireless device 106.

The CN 102 may provide the wireless device 106 with an interface to one or more data networks (DNs), such as public DNS (e.g., the Internet), private DNs, and/or intra-operator DNs. As part of the interface functionality, the CN 102 may set up end-to-end connections between the wireless device 106 and the one or more DNs, authenticate the wireless device 106, and provide charging functionality.

The RAN 104 may connect the CN 102 to the wireless device 106 through radio communications over an air interface. As part of the radio communications, the RAN 104 may provide scheduling, radio resource management, and retransmission protocols. The communication direction from the RAN 104 to the wireless device 106 over the air interface is known as the downlink and the communication direction from the wireless device 106 to the RAN 104 over the air interface is known as the uplink. Downlink transmissions may be separated from uplink transmissions using frequency division duplexing (FDD), time-division duplexing (TDD), and/or some combination of the two duplexing techniques.

The term wireless device may be used throughout this disclosure to refer to and encompass any mobile device or fixed (non-mobile) device for which wireless communication is needed or usable. For example, a wireless device may be a telephone, smart phone, tablet, computer, laptop, sensor, meter, wearable device, Internet of Things (IoT) device, vehicle road side unit (RSU), relay node, automobile, and/or any combination thereof. The term wireless device encompasses other terminology, including user equipment (UE), user terminal (UT), access terminal (AT), mobile station, handset, wireless transmit and receive unit (WTRU), and/or wireless communication device.

The RAN 104 may include one or more base stations (not shown). The term base station may be used throughout this disclosure to refer to and encompass a Node B (associated with UMTS and/or 3G standards), an Evolved Node B (eNB, associated with E-UTRA and/or 4G standards), a remote radio head (RRH), a baseband processing unit coupled to one or more RRHs, a repeater node or relay node used to extend the coverage area of a donor node, a Next Generation Evolved Node B (ng-eNB), a Generation Node B (gNB, associated with NR and/or 5G standards), an access point (AP, associated with, for example, WiFi or any other suitable wireless communication standard), and/or any combination thereof. A base station may comprise at least one gNB Central Unit (gNB-CU) and at least one a gNB Distributed Unit (gNB-DU).

A base station included in the RAN 104 may include one or more sets of antennas for communicating with the wireless device 106 over the air interface. For example, one or more of the base stations may include three sets of antennas to respectively control three cells (or sectors). The size of a cell may be determined by a range at which a receiver (e.g., a base station receiver) can successfully receive the transmissions from a transmitter (e.g., a wireless device transmitter) operating in the cell. Together, the cells of the base stations may provide radio coverage to the wireless device 106 over a wide geographic area to support wireless device mobility.

In addition to three-sector sites, other implementations of base stations are possible. For example, one or more of the base stations in the RAN 104 may be implemented as a sectored site with more or less than three sectors. One or more of the base stations in the RAN 104 may be implemented as an access point, as a baseband processing unit coupled to several remote radio heads (RRHs), and/or as a repeater or relay node used to extend the coverage area of a donor node. A baseband processing unit coupled to RRHs may be part of a centralized or cloud RAN architecture, where the baseband processing unit may be either centralized in a pool of baseband processing units or virtualized. A repeater node may amplify and rebroadcast a radio signal received from a donor node. A relay node may perform the same/similar functions as a repeater node but may decode the radio signal received from the donor node to remove noise before amplifying and rebroadcasting the radio signal.

The RAN 104 may be deployed as a homogenous network of macrocell base stations that have similar antenna patterns and similar high-level transmit powers. The RAN 104 may be deployed as a heterogeneous network. In heterogeneous networks, small cell base stations may be used to provide small coverage areas, for example, coverage areas that overlap with the comparatively larger coverage areas provided by macrocell base stations. The small coverage areas may be provided in areas with high data traffic (or so-called “hotspots”) or in areas with weak macrocell coverage. Examples of small cell base stations include, in order of decreasing coverage area, microcell base stations, picocell base stations, and femtocell base stations or home base stations.

The Third-Generation Partnership Project (3GPP) was formed in 1998 to provide global standardization of specifications for mobile communication networks similar to the mobile communication network 100 in FIG. 1A. To date, 3GPP has produced specifications for three generations of mobile networks: a third generation (3G) network known as Universal Mobile Telecommunications System (UMTS), a fourth generation (4G) network known as Long-Term Evolution (LTE), and a fifth generation (5G) network known as 5G System (5GS). Embodiments of the present disclosure are described with reference to the RAN of a 3GPP 5G network, referred to as next-generation RAN (NG-RAN). Embodiments may be applicable to RANs of other mobile communication networks, such as the RAN 104 in FIG. 1A, the RANs of earlier 3G and 4G networks, and those of future networks yet to be specified (e.g., a 3GPP 6G network). NG-RAN implements 5G radio access technology known as New Radio (NR) and may be provisioned to implement 4G radio access technology or other radio access technologies, including non-3GPP radio access technologies.

FIG. 1B illustrates another example mobile communication network 150 in which embodiments of the present disclosure may be implemented. Mobile communication network 150 may be, for example, a PLMN run by a network operator. As illustrated in FIG. 1B, mobile communication network 150 includes a 5G core network (5G-CN) 152, an NG-RAN 154, and UEs 156A and 156B (collectively UEs 156). These components may be implemented and operate in the same or similar manner as corresponding components described with respect to FIG. 1A.

The 5G-CN 152 provides the UEs 156 with an interface to one or more DNs, such as public DNS (e.g., the Internet), private DNs, and/or intra-operator DNs. As part of the interface functionality, the 5G-CN 152 may set up end-to-end connections between the UEs 156 and the one or more DNs, authenticate the UEs 156, and provide charging functionality. Compared to the CN of a 3GPP 4G network, the basis of the 5G-CN 152 may be a service-based architecture. This means that the architecture of the nodes making up the 5G-CN 152 may be defined as network functions that offer services via interfaces to other network functions. The network functions of the 5G-CN 152 may be implemented in several ways, including as network elements on dedicated or shared hardware, as software instances running on dedicated or shared hardware, or as virtualized functions instantiated on a platform (e.g., a cloud-based platform).

As illustrated in FIG. 1B, the 5G-CN 152 includes an Access and Mobility Management Function (AMF) 158A and a User Plane Function (UPF) 158B, which are shown as one component AMF/UPF 158 in FIG. 1B for ease of illustration. The UPF 158B may serve as a gateway between the NG-RAN 154 and the one or more DNs. The UPF 158B may perform functions such as packet routing and forwarding, packet inspection and user plane policy rule enforcement, traffic usage reporting, uplink classification to support routing of traffic flows to the one or more DNS, quality of service (QOS) handling for the user plane (e.g., packet filtering, gating, uplink/downlink rate enforcement, and uplink traffic verification), downlink packet buffering, and downlink data notification triggering. The UPF 158B may serve as an anchor point for intra-/inter-Radio Access Technology (RAT) mobility, an external protocol (or packet) data unit (PDU) session point of interconnect to the one or more DNs, and/or a branching point to support a multi-homed PDU session. The UEs 156 may be configured to receive services through a PDU session, which is a logical connection between a UE and a DN.

The AMF 158A may perform functions such as Non-Access Stratum (NAS) signaling termination, NAS signaling security, Access Stratum (AS) security control, inter-CN node signaling for mobility between 3GPP access networks, idle mode UE reachability (e.g., control and execution of paging retransmission), registration area management, intra-system and inter-system mobility support, access authentication, access authorization including checking of roaming rights, mobility management control (subscription and policies), network slicing support, and/or session management function (SMF) selection. NAS may refer to the functionality operating between a CN and a UE, and AS may refer to the functionality operating between the UE and a RAN.

The 5G-CN 152 may include one or more additional network functions that are not shown in FIG. 1B for the sake of clarity. For example, the 5G-CN 152 may include one or more of a Session Management Function (SMF), an NR Repository Function (NRF), a Policy Control Function (PCF), a Network Exposure Function (NEF), a Unified Data Management (UDM), an Application Function (AF), and/or an Authentication Server Function (AUSF).

The NG-RAN 154 may connect the 5G-CN 152 to the UEs 156 through radio communications over the air interface. The NG-RAN 154 may include one or more gNBs, illustrated as gNB 160A and gNB 160B (collectively gNBs 160) and/or one or more ng-eNBs, illustrated as ng-eNB 162A and ng-eNB 162B (collectively ng-eNBs 162). The gNBs 160 and ng-eNBs 162 may be more generically referred to as base stations. The gNBs 160 and ng-eNBs 162 may include one or more sets of antennas for communicating with the UEs 156 over an air interface. For example, one or more of the gNBs 160 and/or one or more of the ng-eNBs 162 may include three sets of antennas to respectively control three cells (or sectors). Together, the cells of the gNBs 160 and the ng-eNBs 162 may provide radio coverage to the UEs 156 over a wide geographic area to support UE mobility.

As shown in FIG. 1B, the gNBs 160 and/or the ng-eNBs 162 may be connected to the 5G-CN 152 by means of an NG interface and to other base stations by an Xn interface. The NG and Xn interfaces may be established using direct physical connections and/or indirect connections over an underlying transport network, such as an internet protocol (IP) transport network. The gNBs 160 and/or the ng-eNBs 162 may be connected to the UEs 156 by means of a Uu interface. For example, as illustrated in FIG. 1B, gNB 160A may be connected to the UE 156A by means of a Uu interface. The NG, Xn, and Uu interfaces are associated with a protocol stack. The protocol stacks associated with the interfaces may be used by the network elements in FIG. 1B to exchange data and signaling messages and may include two planes: a user plane and a control plane. The user plane may handle data of interest to a user. The control plane may handle signaling messages of interest to the network elements.

The gNBs 160 and/or the ng-eNBs 162 may be connected to one or more AMF/UPF functions of the 5G-CN 152, such as the AMF/UPF 158, by means of one or more NG interfaces. For example, the gNB 160A may be connected to the UPF 158B of the AMF/UPF 158 by means of an NG-User plane (NG-U) interface. The NG-U interface may provide delivery (e.g., non-guaranteed delivery) of user plane PDUs between the gNB 160A and the UPF 158B. The gNB 160A may be connected to the AMF 158A by means of an NG-Control plane (NG-C) interface. The NG-C interface may provide, for example, NG interface management, UE context management, UE mobility management, transport of NAS messages, paging, PDU session management, and configuration transfer and/or warning message transmission.

The gNBs 160 may provide NR user plane and control plane protocol terminations towards the UEs 156 over the Uu interface. For example, the gNB 160A may provide NR user plane and control plane protocol terminations toward the UE 156A over a Uu interface associated with a first protocol stack. The ng-eNBs 162 may provide Evolved UMTS Terrestrial Radio Access (E-UTRA) user plane and control plane protocol terminations towards the UEs 156 over a Uu interface, where E-UTRA refers to the 3GPP 4G radio-access technology. For example, the ng-eNB 162B may provide E-UTRA user plane and control plane protocol terminations towards the UE 156B over a Uu interface associated with a second protocol stack.

The 5G-CN 152 was described as being configured to handle NR and 4G radio accesses. It will be appreciated by one of ordinary skill in the art that it may be possible for NR to connect to a 4G core network in a mode known as “non-standalone operation.” In non-standalone operation, a 4G core network is used to provide (or at least support) control-plane functionality (e.g., initial access, mobility, and paging). Although only one AMF/UPF 158 is shown in FIG. 1B, one gNB or ng-eNB may be connected to multiple AMF/UPF nodes to provide redundancy and/or to load share across the multiple AMF/UPF nodes.

As discussed, an interface (e.g., Uu, Xn, and NG interfaces) between the network elements in FIG. 1B may be associated with a protocol stack that the network elements use to exchange data and signaling messages. A protocol stack may include two planes: a user plane and a control plane. The user plane may handle data of interest to a user, and the control plane may handle signaling messages of interest to the network elements.

FIG. 2A and FIG. 2B respectively illustrate examples of NR user plane and NR control plane protocol stacks for the Uu interface that lies between a UE 210 and a gNB 220. The protocol stacks illustrated in FIG. 2A and FIG. 2B may be the same or similar to those used for the Uu interface between, for example, the UE 156A and the gNB 160A shown in FIG. 1B.

FIG. 2A illustrates a NR user plane protocol stack comprising five layers implemented in the UE 210 and the gNB 220. At the bottom of the protocol stack, physical layers (PHYs) 211 and 221 may provide transport services to the higher layers of the protocol stack and may correspond to layer 1 of the Open Systems Interconnection (OSI) model. The next four protocols above PHYs 211 and 221 comprise media access control layers (MACs) 212 and 222, radio link control layers (RLCs) 213 and 223, packet data convergence protocol layers (PDCPs) 214 and 224, and service data application protocol layers (SDAPs) 215 and 225. Together, these four protocols may make up layer 2, or the data link layer, of the OSI model.

FIG. 3 illustrates an example of services provided between protocol layers of the NR user plane protocol stack. Starting from the top of FIG. 2A and FIG. 3, the SDAPs 215 and 225 may perform QoS flow handling. The UE 210 may receive services through a PDU session, which may be a logical connection between the UE 210 and a DN. The PDU session may have one or more QoS flows. A UPF of a CN (e.g., the UPF 158B) may map IP packets to the one or more QoS flows of the PDU session based on QoS requirements (e.g., in terms of delay, data rate, and/or error rate). The SDAPs 215 and 225 may perform mapping/de-mapping between the one or more QoS flows and one or more data radio bearers. The mapping/de-mapping between the QoS flows and the data radio bearers may be determined by the SDAP 225 at the gNB 220. The SDAP 215 at the UE 210 may be informed of the mapping between the QoS flows and the data radio bearers through reflective mapping or control signaling received from the gNB 220. For reflective mapping, the SDAP 225 at the gNB 220 may mark the downlink packets with a QoS flow indicator (QFI), which may be observed by the SDAP 215 at the UE 210 to determine the mapping/de-mapping between the QoS flows and the data radio bearers.

The PDCPs 214 and 224 may perform header compression/decompression to reduce the amount of data that needs to be transmitted over the air interface, ciphering/deciphering to prevent unauthorized decoding of data transmitted over the air interface, and integrity protection (to ensure control messages originate from intended sources. The PDCPs 214 and 224 may perform retransmissions of undelivered packets, in-sequence delivery and reordering of packets, and removal of packets received in duplicate due to, for example, an intra-gNB handover. The PDCPs 214 and 224 may perform packet duplication to improve the likelihood of the packet being received and, at the receiver, remove any duplicate packets. Packet duplication may be useful for services that require high reliability.

Although not shown in FIG. 3, PDCPs 214 and 224 may perform mapping/de-mapping between a split radio bearer and RLC channels in a dual connectivity scenario. Dual connectivity is a technique that allows a UE to connect to two cells or, more generally, two cell groups: a master cell group (MCG) and a secondary cell group (SCG). A split bearer is when a single radio bearer, such as one of the radio bearers provided by the PDCPs 214 and 224 as a service to the SDAPs 215 and 225, is handled by cell groups in dual connectivity. The PDCPs 214 and 224 may map/de-map the split radio bearer between RLC channels belonging to cell groups.

The RLCs 213 and 223 may perform segmentation, retransmission through Automatic Repeat Request (ARQ), and removal of duplicate data units received from MACs 212 and 222, respectively. The RLCs 213 and 223 may support three transmission modes: transparent mode (TM); unacknowledged mode (UM); and acknowledged mode (AM). Based on the transmission mode an RLC is operating, the RLC may perform one or more of the noted functions. The RLC configuration may be per logical channel with no dependency on numerologies and/or Transmission Time Interval (TTI) durations. As shown in FIG. 3, the RLCs 213 and 223 may provide RLC channels as a service to PDCPs 214 and 224, respectively.

The MACs 212 and 222 may perform multiplexing/demultiplexing of logical channels and/or mapping between logical channels and transport channels. The multiplexing/demultiplexing may include multiplexing/demultiplexing of data units, belonging to the one or more logical channels, into/from Transport Blocks (TBs) delivered to/from the PHYs 211 and 221. The MAC 222 may be configured to perform scheduling, scheduling information reporting, and priority handling between UEs by means of dynamic scheduling. Scheduling may be performed in the gNB 220 (at the MAC 222) for downlink and uplink. The MACs 212 and 222 may be configured to perform error correction through Hybrid Automatic Repeat Request (HARQ) (e.g., one HARQ entity per carrier in case of Carrier Aggregation (CA), priority handling between logical channels of the UE 210 by means of logical channel prioritization, and/or padding. The MACs 212 and 222 may support one or more numerologies and/or transmission timings. In an example, mapping restrictions in a logical channel prioritization may control which numerology and/or transmission timing a logical channel may use. As shown in FIG. 3, the MACs 212 and 222 may provide logical channels as a service to the RLCs 213 and 223.

The PHYs 211 and 221 may perform mapping of transport channels to physical channels and digital and analog signal processing functions for sending and receiving information over the air interface. These digital and analog signal processing functions may include, for example, coding/decoding and modulation/demodulation. The PHYs 211 and 221 may perform multi-antenna mapping. As shown in FIG. 3, the PHYs 211 and 221 may provide one or more transport channels as a service to the MACs 212 and 222.

FIG. 4A illustrates an example downlink data flow through the NR user plane protocol stack. FIG. 4A illustrates a downlink data flow of three IP packets (n, n+1, and m) through the NR user plane protocol stack to generate two TBs at the gNB 220. An uplink data flow through the NR user plane protocol stack may be similar to the downlink data flow depicted in FIG. 4A.

The downlink data flow of FIG. 4A begins when SDAP 225 receives the three IP packets from one or more QoS flows and maps the three packets to radio bearers. In FIG. 4A, the SDAP 225 maps IP packets n and n+1 to a first radio bearer 402 and maps IP packet m to a second radio bearer 404. An SDAP header (labeled with an “H” in FIG. 4A) is added to an IP packet. The data unit from/to a higher protocol layer is referred to as a service data unit (SDU) of the lower protocol layer and the data unit to/from a lower protocol layer is referred to as a protocol data unit (PDU) of the higher protocol layer. As shown in FIG. 4A, the data unit from the SDAP 225 is an SDU of lower protocol layer PDCP 224 and is a PDU of the SDAP 225.

The remaining protocol layers in FIG. 4A may perform their associated functionality (e.g., with respect to FIG. 3), add corresponding headers, and forward their respective outputs to the next lower layer. For example, the PDCP 224 may perform IP-header compression and ciphering and forward its output to the RLC 223. The RLC 223 may optionally perform segmentation (e.g., as shown for IP packet m in FIG. 4A) and forward its output to the MAC 222. The MAC 222 may multiplex a number of RLC PDUs and may attach a MAC subheader to an RLC PDU to form a transport block. In NR, the MAC subheaders may be distributed across the MAC PDU, as illustrated in FIG. 4A. In LTE, the MAC subheaders may be entirely located at the beginning of the MAC PDU. The NR MAC PDU structure may reduce processing time and associated latency because the MAC PDU subheaders may be computed before the full MAC PDU is assembled.

FIG. 4B illustrates an example format of a MAC subheader in a MAC PDU. The MAC subheader includes: an SDU length field for indicating the length (e.g., in bytes) of the MAC SDU to which the MAC subheader corresponds; a logical channel identifier (LCID) field for identifying the logical channel from which the MAC SDU originated to aid in the demultiplexing process; a flag (F) for indicating the size of the SDU length field; and a reserved bit (R) field for future use.

FIG. 4B further illustrates MAC control elements (CEs) inserted into the MAC PDU by a MAC, such as MAC 223 or MAC 222. For example, FIG. 4B illustrates two MAC CEs inserted into the MAC PDU. MAC CEs may be inserted at the beginning of a MAC PDU for downlink transmissions (as shown in FIG. 4B) and at the end of a MAC PDU for uplink transmissions. MAC CEs may be used for in-band control signaling. Example MAC CEs include: scheduling-related MAC CEs, such as buffer status reports and power headroom reports; activation/deactivation MAC CEs, such as those for activation/deactivation of PDCP duplication detection, channel state information (C SI) reporting, sounding reference signal (SRS) transmission, and prior configured components; discontinuous reception (DRX) related MAC CEs; timing advance MAC CEs; and random access related MAC CEs. A MAC CE may be preceded by a MAC subheader with a similar format as described for MAC SDUs and may be identified with a reserved value in the LCID field that indicates the type of control information included in the MAC CE.

Before describing the NR control plane protocol stack, logical channels, transport channels, and physical channels are first described as well as a mapping between the channel types. One or more of the channels may be used to carry out functions associated with the NR control plane protocol stack described later below.

FIG. 5A and FIG. 5B illustrate, for downlink and uplink respectively, a mapping between logical channels, transport channels, and physical channels. Information is passed through channels between the RLC, the MAC, and the PHY of the NR protocol stack. A logical channel may be used between the RLC and the MAC and may be classified as a control channel that carries control and configuration information in the NR control plane or as a traffic channel that carries data in the NR user plane. A logical channel may be classified as a dedicated logical channel that is dedicated to a specific UE or as a common logical channel that may be used by more than one UE. A logical channel may also be defined by the type of information it carries. The set of logical channels defined by NR include, for example:

• • a paging control channel (PCCH) for carrying paging messages used to page a UE whose location is not known to the network on a cell level;
  • a broadcast control channel (BCCH) for carrying system information messages in the form of a master information block (MIB) and several system information blocks (SIBs), wherein the system information messages may be used by the UEs to obtain information about how a cell is configured and how to operate within the cell;
  • a common control channel (CCCH) for carrying control messages together with random access;
  • a dedicated control channel (DCCH) for carrying control messages to/from a specific the UE to configure the UE; and
  • a dedicated traffic channel (DTCH) for carrying user data to/from a specific the UE.

Transport channels are used between the MAC and PHY layers and may be defined by how the information they carry is transmitted over the air interface. The set of transport channels defined by NR include, for example:

• • a paging channel (PCH) for carrying paging messages that originated from the PCCH;
  • a broadcast channel (BCH) for carrying the MIB from the BCCH;
  • a downlink shared channel (DL-SCH) for carrying downlink data and signaling messages, including the SIBs from the BCCH;
  • an uplink shared channel (UL-SCH) for carrying uplink data and signaling messages; and
  • a random access channel (RACH) for allowing a UE to contact the network without any prior scheduling.

The PHY may use physical channels to pass information between processing levels of the PHY. A physical channel may have an associated set of time-frequency resources for carrying the information of one or more transport channels. The PHY may generate control information to support the low-level operation of the PHY and provide the control information to the lower levels of the PHY via physical control channels, known as L1/L2 control channels. The set of physical channels and physical control channels defined by NR include, for example:

• • a physical broadcast channel (PBCH) for carrying the MIB from the BCH;
  • a physical downlink shared channel (PDSCH) for carrying downlink data and signaling messages from the DL-SCH, as well as paging messages from the PCH;
  • a physical downlink control channel (PDCCH) for carrying downlink control information (DCI), which may include downlink scheduling commands, uplink scheduling grants, and uplink power control commands;
  • a physical uplink shared channel (PUSCH) for carrying uplink data and signaling messages from the UL-SCH and in some instances uplink control information (UCI) as described below;
  • a physical uplink control channel (PUCCH) for carrying UCI, which may include HARQ acknowledgments, channel quality indicators (CQI), pre-coding matrix indicators (PMI), rank indicators (RI), and scheduling requests (SR); and
  • a physical random access channel (PRACH) for random access.

Similar to the physical control channels, the physical layer generates physical signals to support the low-level operation of the physical layer. As shown in FIG. 5A and FIG. 5B, the physical layer signals defined by NR include: primary synchronization signals (PSS), secondary synchronization signals (SSS), channel state information reference signals (CSI-RS), demodulation reference signals (DMRS), sounding reference signals (SRS), and phase-tracking reference signals (PT-RS). These physical layer signals will be described in greater detail below.

FIG. 2B illustrates an example NR control plane protocol stack. As shown in FIG. 2B, the NR control plane protocol stack may use the same/similar first four protocol layers as the example NR user plane protocol stack. These four protocol layers include the PHYs 211 and 221, the MACs 212 and 222, the RLCs 213 and 223, and the PDCPs 214 and 224. Instead of having the SDAPs 215 and 225 at the top of the stack as in the NR user plane protocol stack, the NR control plane stack has radio resource controls (RRCs) 216 and 226 and NAS protocols 217 and 237 at the top of the NR control plane protocol stack.

The NAS protocols 217 and 237 may provide control plane functionality between the UE 210 and the AMF 230 (e.g., the AMF 158A) or, more generally, between the UE 210 and the CN. The NAS protocols 217 and 237 may provide control plane functionality between the UE 210 and the AMF 230 via signaling messages, referred to as NAS messages. There is no direct path between the UE 210 and the AMF 230 through which the NAS messages can be transported. The NAS messages may be transported using the AS of the Uu and NG interfaces. NAS protocols 217 and 237 may provide control plane functionality such as authentication, security, connection setup, mobility management, and session management.

The RRCs 216 and 226 may provide control plane functionality between the UE 210 and the gNB 220 or, more generally, between the UE 210 and the RAN. The RRCs 216 and 226 may provide control plane functionality between the UE 210 and the gNB 220 via signaling messages, referred to as RRC messages. RRC messages may be transmitted between the UE 210 and the RAN using signaling radio bearers and the same/similar PDCP, RLC, MAC, and PHY protocol layers. The MAC may multiplex control-plane and user-plane data into the same transport block (TB). The RRCs 216 and 226 may provide control plane functionality such as: broadcast of system information related to AS and NAS; paging initiated by the CN or the RAN; establishment, maintenance and release of an RRC connection between the UE 210 and the RAN; security functions including key management; establishment, configuration, maintenance and release of signaling radio bearers and data radio bearers; mobility functions; QoS management functions; the UE measurement reporting and control of the reporting; detection of and recovery from radio link failure (RLF); and/or NAS message transfer. As part of establishing an RRC connection, RRCs 216 and 226 may establish an RRC context, which may involve configuring parameters for communication between the UE 210 and the RAN.

FIG. 6 is an example diagram showing RRC state transitions of a UE. The UE may be the same or similar to the wireless device 106 depicted in FIG. 1A, the UE 210 depicted in FIG. 2A and FIG. 2B, or any other wireless device described in the present disclosure. As illustrated in FIG. 6, a UE may be in at least one of three RRC states: RRC connected 602 (e.g., RRC_CONNECTED), RRC idle 604 (e.g., RRC_IDLE), and RRC inactive 606 (e.g., RRC_INACTIVE).

In RRC connected 602, the UE has an established RRC context and may have at least one RRC connection with a base station. The base station may be similar to one of the one or more base stations included in the RAN 104 depicted in FIG. 1A, one of the gNBs 160 or ng-eNBs 162 depicted in FIG. 1B, the gNB 220 depicted in FIG. 2A and FIG. 2B, or any other base station described in the present disclosure. The base station with which the UE is connected may have the RRC context for the UE. The RRC context, referred to as the UE context, may comprise parameters for communication between the UE and the base station. These parameters may include, for example: one or more AS contexts; one or more radio link configuration parameters; bearer configuration information (e.g., relating to a data radio bearer, signaling radio bearer, logical channel, QoS flow, and/or PDU session); security information; and/or PHY, MAC, RLC, PDCP, and/or SDAP layer configuration information. While in RRC connected 602, mobility of the UE may be managed by the RAN (e.g., the RAN 104 or the NG-RAN 154). The UE may measure the signal levels (e.g., reference signal levels) from a serving cell and neighboring cells and report these measurements to the base station currently serving the UE. The UE's serving base station may request a handover to a cell of one of the neighboring base stations based on the reported measurements. The RRC state may transition from RRC connected 602 to RRC idle 604 through a connection release procedure 608 or to RRC inactive 606 through a connection inactivation procedure 610.

In RRC idle 604, an RRC context may not be established for the UE. In RRC idle 604, the UE may not have an RRC connection with the base station. While in RRC idle 604, the UE may be in a sleep state for the majority of the time (e.g., to conserve battery power). The UE may wake up periodically (e.g., once in every discontinuous reception cycle) to monitor for paging messages from the RAN. Mobility of the UE may be managed by the UE through a procedure known as cell reselection. The RRC state may transition from RRC idle 604 to RRC connected 602 through a connection establishment procedure 612, which may involve a random access procedure as discussed in greater detail below.

In RRC inactive 606, the RRC context previously established is maintained in the UE and the base station. This allows for a fast transition to RRC connected 602 with reduced signaling overhead as compared to the transition from RRC idle 604 to RRC connected 602. While in RRC inactive 606, the UE may be in a sleep state and mobility of the UE may be managed by the UE through cell reselection. The RRC state may transition from RRC inactive 606 to RRC connected 602 through a connection resume procedure 614 or to RRC idle 604 though a connection release procedure 616 that may be the same as or similar to connection release procedure 608.

An RRC state may be associated with a mobility management mechanism. In RRC idle 604 and RRC inactive 606, mobility is managed by the UE through cell reselection. The purpose of mobility management in RRC idle 604 and RRC inactive 606 is to allow the network to be able to notify the UE of an event via a paging message without having to broadcast the paging message over the entire mobile communications network. The mobility management mechanism used in RRC idle 604 and RRC inactive 606 may allow the network to track the UE on a cell-group level so that the paging message may be broadcast over the cells of the cell group that the UE currently resides within instead of the entire mobile communication network. The mobility management mechanisms for RRC idle 604 and RRC inactive 606 track the UE on a cell-group level. They may do so using different granularities of grouping. For example, there may be three levels of cell-grouping granularity: individual cells; cells within a RAN area identified by a RAN area identifier (RAI); and cells within a group of RAN areas, referred to as a tracking area and identified by a tracking area identifier (TAI).

Tracking areas may be used to track the UE at the CN level. The CN (e.g., the CN 102 or the 5G-CN 152) may provide the UE with a list of TAIs associated with a UE registration area. If the UE moves, through cell reselection, to a cell associated with a TAI not included in the list of TAIs associated with the UE registration area, the UE may perform a registration update with the CN to allow the CN to update the UE's location and provide the UE with a new the UE registration area.

RAN areas may be used to track the UE at the RAN level. For a UE in RRC inactive 606 state, the UE may be assigned a RAN notification area. A RAN notification area may comprise one or more cell identities, a list of RAIs, or a list of TAIs. In an example, a base station may belong to one or more RAN notification areas. In an example, a cell may belong to one or more RAN notification areas. If the UE moves, through cell reselection, to a cell not included in the RAN notification area assigned to the UE, the UE may perform a notification area update with the RAN to update the UE's RAN notification area.

A base station storing an RRC context for a UE or a last serving base station of the UE may be referred to as an anchor base station. An anchor base station may maintain an RRC context for the UE at least during a period of time that the UE stays in a RAN notification area of the anchor base station and/or during a period of time that the UE stays in RRC inactive 606.

A gNB, such as gNBs 160 in FIG. 1B, may be split in two parts: a central unit (gNB-CU), and one or more distributed units (gNB-DU). A gNB-CU may be coupled to one or more gNB-DUs using an F1 interface. The gNB-CU may comprise the RRC, the PDCP, and the SDAP. A gNB-DU may comprise the RLC, the MAC, and the PHY.

In NR, the physical signals and physical channels (discussed with respect to FIG. 5A and FIG. 5B) may be mapped onto orthogonal frequency divisional multiplexing (OFDM) symbols. OFDM is a multicarrier communication scheme that transmits data over F orthogonal subcarriers (or tones). Before transmission, the data may be mapped to a series of complex symbols (e.g., M-quadrature amplitude modulation (M-QAM) or M-phase shift keying (M-PSK) symbols), referred to as source symbols, and divided into F parallel symbol streams. The F parallel symbol streams may be treated as though they are in the frequency domain and used as inputs to an Inverse Fast Fourier Transform (IFFT) block that transforms them into the time domain. The IFFT block may take in F source symbols at a time, one from each of the F parallel symbol streams, and use each source symbol to modulate the amplitude and phase of one of F sinusoidal basis functions that correspond to the F orthogonal subcarriers. The output of the IFFT block may be F time-domain samples that represent the summation of the F orthogonal subcarriers. The F time-domain samples may form a single OFDM symbol. After some processing (e.g., addition of a cyclic prefix) and up-conversion, an OFDM symbol provided by the IFFT block may be transmitted over the air interface on a carrier frequency. The F parallel symbol streams may be mixed using an FFT block before being processed by the IFFT block. This operation produces Discrete Fourier Transform (DFT)-precoded OFDM symbols and may be used by UEs in the uplink to reduce the peak to average power ratio (PAPR). Inverse processing may be performed on the OFDM symbol at a receiver using an FFT block to recover the data mapped to the source symbols.

FIG. 7 illustrates an example configuration of an NR frame into which OFDM symbols are grouped. An NR frame may be identified by a system frame number (SFN). The SFN may repeat with a period of 1024 frames. As illustrated, one NR frame may be 10 milliseconds (ms) in duration and may include 10 subframes that are 1 ms in duration. A subframe may be divided into slots that include, for example, 14 OFDM symbols per slot.

The duration of a slot may depend on the numerology used for the OFDM symbols of the slot. In NR, a flexible numerology is supported to accommodate different cell deployments (e.g., cells with carrier frequencies below 1 GHZ up to cells with carrier frequencies in the mm-wave range). A numerology may be defined in terms of subcarrier spacing and cyclic prefix duration. For a numerology in NR, subcarrier spacings may be scaled up by powers of two from a baseline subcarrier spacing of 15 kHz, and cyclic prefix durations may be scaled down by powers of two from a baseline cyclic prefix duration of 4.7 μs. For example, NR defines numerologies with the following subcarrier spacing/cyclic prefix duration combinations: 15 kHz/4.7 μs; 30 kHz/2.3 μs; 60 KHz/1.2 μs; 120 KHz/0.59 μs; and 240 kHz/0.29 μs.

A slot may have a fixed number of OFDM symbols (e.g., 14 OFDM symbols). A numerology with a higher subcarrier spacing has a shorter slot duration and, correspondingly, more slots per subframe. FIG. 7 illustrates this numerology-dependent slot duration and slots-per-subframe transmission structure (the numerology with a subcarrier spacing of 240 kHz is not shown in FIG. 7 for ease of illustration). A subframe in NR may be used as a numerology-independent time reference, while a slot may be used as the unit upon which uplink and downlink transmissions are scheduled. To support low latency, scheduling in NR may be decoupled from the slot duration and start at any OFDM symbol and last for as many symbols as needed for a transmission. These partial slot transmissions may be referred to as mini-slot or subslot transmissions.

FIG. 8 illustrates an example configuration of a slot in the time and frequency domain for an NR carrier. The slot includes resource elements (REs) and resource blocks (RBs). An RE is the smallest physical resource in NR. An RE spans one OFDM symbol in the time domain by one subcarrier in the frequency domain as shown in FIG. 8. An RB spans twelve consecutive REs in the frequency domain as shown in FIG. 8. An NR carrier may be limited to a width of 275 RBs or 275×12=3300 subcarriers. Such a limitation, if used, may limit the NR carrier to 50, 100, 200, and 400 MHz for subcarrier spacings of 15, 30, 60, and 120 kHz, respectively, where the 400 MHz bandwidth may be set based on a 400 MHz per carrier bandwidth limit.

FIG. 8 illustrates a single numerology being used across the entire bandwidth of the NR carrier. In other example configurations, multiple numerologies may be supported on the same carrier.

NR may support wide carrier bandwidths (e.g., up to 400 MHz for a subcarrier spacing of 120 kHz). Not all UEs may be able to receive the full carrier bandwidth (e.g., due to hardware limitations). Also, receiving the full carrier bandwidth may be prohibitive in terms of UE power consumption. In an example, to reduce power consumption and/or for other purposes, a UE may adapt the size of the UE's receive bandwidth based on the amount of traffic the UE is scheduled to receive. This is referred to as bandwidth adaptation.

NR defines bandwidth parts (BWPs) to support UEs not capable of receiving the full carrier bandwidth and to support bandwidth adaptation. In an example, a BWP may be defined by a subset of contiguous RBs on a carrier. A UE may be configured (e.g., via RRC layer) with one or more downlink BWPs and one or more uplink BWPs per serving cell (e.g., up to four downlink BWPs and up to four uplink BWPs per serving cell). At a given time, one or more of the configured BWPs for a serving cell may be active. These one or more BWPs may be referred to as active BWPs of the serving cell. When a serving cell is configured with a secondary uplink carrier, the serving cell may have one or more first active BWPs in the uplink carrier and one or more second active BWPs in the secondary uplink carrier.

For unpaired spectra, a downlink BWP from a set of configured downlink BWPs may be linked with an uplink BWP from a set of configured uplink BWPs if a downlink BWP index of the downlink BWP and an uplink BWP index of the uplink BWP are the same. For unpaired spectra, a UE may expect that a center frequency for a downlink BWP is the same as a center frequency for an uplink BWP.

For a downlink BWP in a set of configured downlink BWPs on a primary cell (PCell), a base station may configure a UE with one or more control resource sets (CORESETs) for at least one search space. A search space is a set of locations in the time and frequency domains where the UE may find control information. The search space may be a UE-specific search space or a common search space (potentially usable by a plurality of UEs). For example, a base station may configure a UE with a common search space, on a PCell or on a primary secondary cell (PSCell), in an active downlink BWP.

For an uplink BWP in a set of configured uplink BWPs, a BS may configure a UE with one or more resource sets for one or more PUCCH transmissions. A UE may receive downlink receptions (e.g., PDCCH or PDSCH) in a downlink BWP according to a configured numerology (e.g., subcarrier spacing and cyclic prefix duration) for the downlink BWP. The UE may transmit uplink transmissions (e.g., PUCCH or PUSCH) in an uplink BWP according to a configured numerology (e.g., subcarrier spacing and cyclic prefix length for the uplink BWP).

One or more BWP indicator fields may be provided in Downlink Control Information (DCI). A value of a BWP indicator field may indicate which BWP in a set of configured BWPs is an active downlink BWP for one or more downlink receptions. The value of the one or more BWP indicator fields may indicate an active uplink BWP for one or more uplink transmissions.

A base station may semi-statically configure a UE with a default downlink BWP within a set of configured downlink BWPs associated with a PCell. If the base station does not provide the default downlink BWP to the UE, the default downlink BWP may be an initial active downlink BWP. The UE may determine which BWP is the initial active downlink BWP based on a CORESET configuration obtained using the PBCH.

A base station may configure a UE with a BWP inactivity timer value for a PCell. The UE may start or restart a BWP inactivity timer at any appropriate time. For example, the UE may start or restart the BWP inactivity timer (a) when the UE detects a DCI indicating an active downlink BWP other than a default downlink BWP for a paired spectra operation; or (b) when a UE detects a DCI indicating an active downlink BWP or active uplink BWP other than a default downlink BWP or uplink BWP for an unpaired spectra operation. If the UE does not detect DCI during an interval of time (e.g., 1 ms or 0.5 ms), the UE may run the BWP inactivity timer toward expiration (for example, increment from zero to the BWP inactivity timer value, or decrement from the BWP inactivity timer value to zero). When the BWP inactivity timer expires, the UE may switch from the active downlink BWP to the default downlink BWP.

In an example, a base station may semi-statically configure a UE with one or more BWPs. A UE may switch an active BWP from a first BWP to a second BWP in response to receiving a DCI indicating the second BWP as an active BWP and/or in response to an expiry of the BWP inactivity timer (e.g., if the second BWP is the default BWP).

Downlink and uplink BWP switching (where BWP switching refers to switching from a currently active BWP to a not currently active BWP) may be performed independently in paired spectra. In unpaired spectra, downlink and uplink BWP switching may be performed simultaneously. Switching between configured BWPs may occur based on RRC signaling, DCI, expiration of a BWP inactivity timer, and/or an initiation of random access.

FIG. 9 illustrates an example of bandwidth adaptation using three configured BWPs for an NR carrier. A UE configured with the three BWPs may switch from one BWP to another BWP at a switching point. In the example illustrated in FIG. 9, the BWPs include: a BWP 902 with a bandwidth of 40 MHz and a subcarrier spacing of 15 kHz; a BWP 904 with a bandwidth of 10 MHz and a subcarrier spacing of 15 kHz; and a BWP 906 with a bandwidth of 20 MHz and a subcarrier spacing of 60 KHz. The BWP 902 may be an initial active BWP, and the BWP 904 may be a default BWP. The UE may switch between BWPs at switching points. In the example of FIG. 9, the UE may switch from the BWP 902 to the BWP 904 at a switching point 908. The switching at the switching point 908 may occur for any suitable reason, for example, in response to an expiry of a BWP inactivity timer (indicating switching to the default BWP) and/or in response to receiving a DCI indicating BWP 904 as the active BWP. The UE may switch at a switching point 910 from active BWP 904 to BWP 906 in response to receiving a DCI indicating BWP 906 as the active BWP. The UE may switch at a switching point 912 from active BWP 906 to BWP 904 in response to an expiry of a BWP inactivity timer and/or in response to receiving a DCI indicating BWP 904 as the active BWP. The UE may switch at a switching point 914 from active BWP 904 to BWP 902 in response to receiving a DCI indicating BWP 902 as the active BWP.

If a UE is configured for a secondary cell with a default downlink BWP in a set of configured downlink BWPs and a timer value, UE procedures for switching BWPs on a secondary cell may be the same/similar as those on a primary cell. For example, the UE may use the timer value and the default downlink BWP for the secondary cell in the same/similar manner as the UE would use these values for a primary cell.

To provide for greater data rates, two or more carriers can be aggregated and simultaneously transmitted to/from the same UE using carrier aggregation (CA). The aggregated carriers in CA may be referred to as component carriers (CCs). When CA is used, there are a number of serving cells for the UE, one for a CC. The CCs may have three configurations in the frequency domain.

FIG. 10A illustrates the three CA configurations with two CCs. In the intraband, contiguous configuration 1002, the two CCs are aggregated in the same frequency band (frequency band A) and are located directly adjacent to each other within the frequency band. In the intraband, non-contiguous configuration 1004, the two CCs are aggregated in the same frequency band (frequency band A) and are separated in the frequency band by a gap. In the interband configuration 1006, the two CCs are located in frequency bands (frequency band A and frequency band B).

In an example, up to 32 CCs may be aggregated. The aggregated CCs may have the same or different bandwidths, subcarrier spacing, and/or duplexing schemes (TDD or FDD). A serving cell for a UE using CA may have a downlink CC. For FDD, one or more uplink CCs may be optionally configured for a serving cell. The ability to aggregate more downlink carriers than uplink carriers may be useful, for example, when the UE has more data traffic in the downlink than in the uplink.

When CA is used, one of the aggregated cells for a UE may be referred to as a primary cell (PCell). The PCell may be the serving cell that the UE initially connects to at RRC connection establishment, reestablishment, and/or handover. The PCell may provide the UE with NAS mobility information and the security input. UEs may have different PCells. In the downlink, the carrier corresponding to the PCell may be referred to as the downlink primary CC (DL PCC). In the uplink, the carrier corresponding to the PCell may be referred to as the uplink primary CC (UL PCC). The other aggregated cells for the UE may be referred to as secondary cells (SCells). In an example, the SCells may be configured after the PCell is configured for the UE. For example, an SCell may be configured through an RRC Connection Reconfiguration procedure. In the downlink, the carrier corresponding to an SCell may be referred to as a downlink secondary CC (DL SCC). In the uplink, the carrier corresponding to the SCell may be referred to as the uplink secondary CC (UL SCC).

Configured SCells for a UE may be activated and deactivated based on, for example, traffic and channel conditions. Deactivation of an SCell may mean that PDCCH and PDSCH reception on the SCell is stopped and PUSCH, SRS, and CQI transmissions on the SCell are stopped. Configured SCells may be activated and deactivated using a MAC CE with respect to FIG. 4B. For example, a MAC CE may use a bitmap (e.g., one bit per SCell) to indicate which SCells (e.g., in a subset of configured SCells) for the UE are activated or deactivated. Configured SCells may be deactivated in response to an expiration of an SCell deactivation timer (e.g., one SCell deactivation timer per SCell).

Downlink control information, such as scheduling assignments and scheduling grants, for a cell may be transmitted on the cell corresponding to the assignments and grants, which is known as self-scheduling. The DCI for the cell may be transmitted on another cell, which is known as cross-carrier scheduling. Uplink control information (e.g., HARQ acknowledgments and channel state feedback, such as CQI, PMI, and/or RI) for aggregated cells may be transmitted on the PUCCH of the PCell. For a larger number of aggregated downlink CCs, the PUCCH of the PCell may become overloaded. Cells may be divided into multiple PUCCH groups.

FIG. 10B illustrates an example of how aggregated cells may be configured into one or more PUCCH groups. A PUCCH group 1010 and a PUCCH group 1050 may include one or more downlink CCs, respectively. In the example of FIG. 10B, the PUCCH group 1010 includes three downlink CCs: a PCell 1011, an SCell 1012, and an SCell 1013. The PUCCH group 1050 includes three downlink CCs in the present example: a PCell 1051, an SCell 1052, and an SCell 1053. One or more uplink CCs may be configured as a PCell 1021, an SCell 1022, and an SCell 1023. One or more other uplink CCs may be configured as a primary SCell (PSCell) 1061, an SCell 1062, and an SCell 1063. Uplink control information (UCI) related to the downlink CCs of the PUCCH group 1010, shown as UCI 1031, UCI 1032, and UCI 1033, may be transmitted in the uplink of the PCell 1021. Uplink control information (UCI) related to the downlink CCs of the PUCCH group 1050, shown as UCI 1071, UCI 1072, and UCI 1073, may be transmitted in the uplink of the PSCell 1061. In an example, if the aggregated cells depicted in FIG. 10B were not divided into the PUCCH group 1010 and the PUCCH group 1050, a single uplink PCell to transmit UCI relating to the downlink CCs, and the PCell may become overloaded. By dividing transmissions of UCI between the PCell 1021 and the PSCell 1061, overloading may be prevented.

A cell, comprising a downlink carrier and optionally an uplink carrier, may be assigned with a physical cell ID and a cell index. The physical cell ID or the cell index may identify a downlink carrier and/or an uplink carrier of the cell, for example, depending on the context in which the physical cell ID is used. A physical cell ID may be determined using a synchronization signal transmitted on a downlink component carrier. A cell index may be determined using RRC messages. In the disclosure, a physical cell ID may be referred to as a carrier ID, and a cell index may be referred to as a carrier index. For example, when the disclosure refers to a first physical cell ID for a first downlink carrier, the disclosure may mean the first physical cell ID is for a cell comprising the first downlink carrier. The same/similar concept may apply to, for example, a carrier activation. When the disclosure indicates that a first carrier is activated, the specification may mean that a cell comprising the first carrier is activated.

In CA, a multi-carrier nature of a PHY may be exposed to a MAC. In an example, a HARQ entity may operate on a serving cell. A transport block may be generated per assignment/grant per serving cell. A transport block and potential HARQ retransmissions of the transport block may be mapped to a serving cell.

In the downlink, a base station may transmit (e.g., unicast, multicast, and/or broadcast) one or more Reference Signals (RSs) to a UE (e.g., PSS, SSS, CSI-RS, DMRS, and/or PT-RS, as shown in FIG. 5A). In the uplink, the UE may transmit one or more RSs to the base station (e.g., DMRS, PT-RS, and/or SRS, as shown in FIG. 5B). The PSS and the SSS may be transmitted by the base station and used by the UE to synchronize the UE to the base station. The PSS and the SSS may be provided in a synchronization signal (SS)/physical broadcast channel (PBCH) block that includes the PSS, the SSS, and the PBCH. The base station may periodically transmit a burst of SS/PBCH blocks.

FIG. 11A illustrates an example of an SS/PBCH block's structure and location. A burst of SS/PBCH blocks may include one or more SS/PBCH blocks (e.g., 4 SS/PBCH blocks, as shown in FIG. 11A). Bursts may be transmitted periodically (e.g., every 2 frames or 20 ms). A burst may be restricted to a half-frame (e.g., a first half-frame having a duration of 5 ms). It will be understood that FIG. 11A is an example, and that these parameters (number of SS/PBCH blocks per burst, periodicity of bursts, position of burst within the frame) may be configured based on, for example: a carrier frequency of a cell in which the SS/PBCH block is transmitted; a numerology or subcarrier spacing of the cell; a configuration by the network (e.g., using RRC signaling); or any other suitable factor. In an example, the UE may assume a subcarrier spacing for the SS/PBCH block based on the carrier frequency being monitored, unless the radio network configured the UE to assume a different subcarrier spacing.

The SS/PBCH block may span one or more OFDM symbols in the time domain (e.g., 4 OFDM symbols, as shown in the example of FIG. 11A) and may span one or more subcarriers in the frequency domain (e.g., 240 contiguous subcarriers). The PSS, the SSS, and the PBCH may have a common center frequency. The PSS may be transmitted first and may span, for example, 1 OFDM symbol and 127 subcarriers. The SSS may be transmitted after the PSS (e.g., two symbols later) and may span 1 OFDM symbol and 127 subcarriers. The PBCH may be transmitted after the PSS (e.g., across the next 3 OFDM symbols) and may span 240 subcarriers.

The location of the SS/PBCH block in the time and frequency domains may not be known to the UE (e.g., if the UE is searching for the cell). To find and select the cell, the UE may monitor a carrier for the PSS. For example, the UE may monitor a frequency location within the carrier. If the PSS is not found after a certain duration (e.g., 20 ms), the UE may search for the PSS at a different frequency location within the carrier, as indicated by a synchronization raster. If the PSS is found at a location in the time and frequency domains, the UE may determine, based on a known structure of the SS/PBCH block, the locations of the SSS and the PBCH, respectively. The SS/PBCH block may be a cell-defining SS block (CD-SSB). In an example, a primary cell may be associated with a CD-SSB. The CD-SSB may be located on a synchronization raster. In an example, a cell selection/search and/or reselection may be based on the CD-SSB

The SS/PBCH block may be used by the UE to determine one or more parameters of the cell. For example, the UE may determine a physical cell identifier (PCI) of the cell based on the sequences of the PSS and the SSS, respectively. The UE may determine a location of a frame boundary of the cell based on the location of the SS/PBCH block. For example, the SS/PBCH block may indicate that it has been transmitted in accordance with a transmission pattern, wherein a SS/PBCH block in the transmission pattern is a known distance from the frame boundary.

The PBCH may use a QPSK modulation and may use forward error correction (FEC). The FEC may use polar coding. One or more symbols spanned by the PBCH may carry one or more DMRSs for demodulation of the PBCH. The PBCH may include an indication of a current system frame number (SFN) of the cell and/or a SS/PBCH block timing index. These parameters may facilitate time synchronization of the UE to the base station. The PBCH may include a master information block (MIB) used to provide the UE with one or more parameters. The MIB may be used by the UE to locate remaining minimum system information (RMSI) associated with the cell. The RMSI may include a System Information Block Type 1 (SIB1). The SIB1 may contain information needed by the UE to access the cell. The UE may use one or more parameters of the MIB to monitor PDCCH, which may be used to schedule PDSCH. The PDSCH may include the SIB1. The SIB1 may be decoded using parameters provided in the MIB. The PBCH may indicate an absence of SIB1. Based on the PBCH indicating the absence of SIB1, the UE may be pointed to a frequency. The UE may search for an SS/PBCH block at the frequency to which the UE is pointed.

The UE may assume that one or more SS/PBCH blocks transmitted with a same SS/PBCH block index are quasi co-located (QCLed) (e.g., having the same/similar Doppler spread, Doppler shift, average gain, average delay, and/or spatial Rx parameters). The UE may not assume QCL for SS/PBCH block transmissions having different SS/PBCH block indices.

SS/PBCH blocks (e.g., those within a half-frame) may be transmitted in spatial directions (e.g., using different beams that span a coverage area of the cell). In an example, a first SS/PBCH block may be transmitted in a first spatial direction using a first beam, and a second SS/PBCH block may be transmitted in a second spatial direction using a second beam.

In an example, within a frequency span of a carrier, a base station may transmit a plurality of SS/PBCH blocks. In an example, a first PCI of a first SS/PBCH block of the plurality of SS/PBCH blocks may be different from a second PCI of a second SS/PBCH block of the plurality of SS/PBCH blocks. The PCIs of SS/PBCH blocks transmitted in different frequency locations may be different or the same.

The CSI-RS may be transmitted by the base station and used by the UE to acquire channel state information (CSI). The base station may configure the UE with one or more CSI-RSs for channel estimation or any other suitable purpose. The base station may configure a UE with one or more of the same/similar CSI-RSs. The UE may measure the one or more CSI-RSs. The UE may estimate a downlink channel state and/or generate a CSI report based on the measuring of the one or more downlink CSI-RSs. The UE may provide the CSI report to the base station. The base station may use feedback provided by the UE (e.g., the estimated downlink channel state) to perform link adaptation.

The base station may semi-statically configure the UE with one or more CSI-RS resource sets. A CSI-RS resource may be associated with a location in the time and frequency domains and a periodicity. The base station may selectively activate and/or deactivate a CSI-RS resource. The base station may indicate to the UE that a CSI-RS resource in the CSI-RS resource set is activated and/or deactivated.

The base station may configure the UE to report CSI measurements. The base station may configure the UE to provide CSI reports periodically, aperiodically, or semi-persistently. For periodic CSI reporting, the UE may be configured with a timing and/or periodicity of a plurality of CSI reports. For aperiodic CSI reporting, the base station may request a CSI report. For example, the base station may command the UE to measure a configured CSI-RS resource and provide a CSI report relating to the measurements. For semi-persistent CSI reporting, the base station may configure the UE to transmit periodically, and selectively activate or deactivate the periodic reporting. The base station may configure the UE with a CSI-RS resource set and CSI reports using RRC signaling.

The CSI-RS configuration may comprise one or more parameters indicating, for example, up to 32 antenna ports. The UE may be configured to employ the same OFDM symbols for a downlink CSI-RS and a control resource set (CORESET) when the downlink CSI-RS and CORESET are spatially QCLed and resource elements associated with the downlink CSI-RS are outside of the physical resource blocks (PRBs) configured for the CORESET. The UE may be configured to employ the same OFDM symbols for downlink CSI-RS and SS/PBCH blocks when the downlink CSI-RS and SS/PBCH blocks are spatially QCLed and resource elements associated with the downlink CSI-RS are outside of PRBs configured for the SS/PBCH blocks.

Downlink DMRSs may be transmitted by a base station and used by a UE for channel estimation. For example, the downlink DMRS may be used for coherent demodulation of one or more downlink physical channels (e.g., PDSCH). An NR network may support one or more variable and/or configurable DMRS patterns for data demodulation. At least one downlink DMRS configuration may support a front-loaded DMRS pattern. A front-loaded DMRS may be mapped over one or more OFDM symbols (e.g., one or two adjacent OFDM symbols). A base station may semi-statically configure the UE with a number (e.g. a maximum number) of front-loaded DMRS symbols for PDSCH. A DMRS configuration may support one or more DMRS ports. For example, for single user-MIMO, a DMRS configuration may support up to eight orthogonal downlink DMRS ports per UE. For multiuser-MIMO, a DMRS configuration may support up to 4 orthogonal downlink DMRS ports per UE. A radio network may support (e.g., at least for CP-OFDM) a common DMRS structure for downlink and uplink, wherein a DMRS location, a DMRS pattern, and/or a scrambling sequence may be the same or different. The base station may transmit a downlink DMRS and a corresponding PDSCH using the same precoding matrix. The UE may use the one or more downlink DMRSs for coherent demodulation/channel estimation of the PDSCH.

In an example, a transmitter (e.g., a base station) may use a precoder matrices for a part of a transmission bandwidth. For example, the transmitter may use a first precoder matrix for a first bandwidth and a second precoder matrix for a second bandwidth. The first precoder matrix and the second precoder matrix may be different based on the first bandwidth being different from the second bandwidth. The UE may assume that a same precoding matrix is used across a set of PRBs. The set of PRBs may be denoted as a precoding resource block group (PRG).

A PDSCH may comprise one or more layers. The UE may assume that at least one symbol with DMRS is present on a layer of the one or more layers of the PDSCH. A higher layer may configure up to 3 DMRSs for the PDSCH.

Downlink PT-RS may be transmitted by a base station and used by a UE for phase-noise compensation. Whether a downlink PT-RS is present or not may depend on an RRC configuration. The presence and/or pattern of the downlink PT-RS may be configured on a UE-specific basis using a combination of RRC signaling and/or an association with one or more parameters employed for other purposes (e.g., modulation and coding scheme (MCS), which may be indicated by DCI. When configured, a dynamic presence of a downlink PT-RS may be associated with one or more DCI parameters comprising at least MCS. An NR network may support a plurality of PT-RS densities defined in the time and/or frequency domains. When present, a frequency domain density may be associated with at least one configuration of a scheduled bandwidth. The UE may assume a same precoding for a DMRS port and a PT-RS port. A number of PT-RS ports may be fewer than a number of DMRS ports in a scheduled resource. Downlink PT-RS may be confined in the scheduled time/frequency duration for the UE. Downlink PT-RS may be transmitted on symbols to facilitate phase tracking at the receiver.

The UE may transmit an uplink DMRS to a base station for channel estimation. For example, the base station may use the uplink DMRS for coherent demodulation of one or more uplink physical channels. For example, the UE may transmit an uplink DMRS with a PUSCH and/or a PUCCH. The uplink DM-RS may span a range of frequencies that is similar to a range of frequencies associated with the corresponding physical channel. The base station may configure the UE with one or more uplink DMRS configurations. At least one DMRS configuration may support a front-loaded DMRS pattern. The front-loaded DMRS may be mapped over one or more OFDM symbols (e.g., one or two adjacent OFDM symbols). One or more uplink DMRSs may be configured to transmit at one or more symbols of a PUSCH and/or a PUCCH. The base station may semi-statically configure the UE with a number (e.g. maximum number) of front-loaded DMRS symbols for the PUSCH and/or the PUCCH, which the UE may use to schedule a single-symbol DMRS and/or a double-symbol DMRS. An NR network may support (e.g., for cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) a common DMRS structure for downlink and uplink, wherein a DMRS location, a DMRS pattern, and/or a scrambling sequence for the DMRS may be the same or different.

A PUSCH may comprise one or more layers, and the UE may transmit at least one symbol with DMRS present on a layer of the one or more layers of the PUSCH. In an example, a higher layer may configure up to three DMRSs for the PUSCH.

Uplink PT-RS (which may be used by a base station for phase tracking and/or phase-noise compensation) may or may not be present depending on an RRC configuration of the UE. The presence and/or pattern of uplink PT-RS may be configured on a UE-specific basis by a combination of RRC signaling and/or one or more parameters employed for other purposes (e.g., Modulation and Coding Scheme (MCS), which may be indicated by DCI. When configured, a dynamic presence of uplink PT-RS may be associated with one or more DCI parameters comprising at least MCS. A radio network may support a plurality of uplink PT-RS densities defined in time/frequency domain. When present, a frequency domain density may be associated with at least one configuration of a scheduled bandwidth. The UE may assume a same precoding for a DMRS port and a PT-RS port. A number of PT-RS ports may be fewer than a number of DMRS ports in a scheduled resource. For example, uplink PT-RS may be confined in the scheduled time/frequency duration for the UE.

SRS may be transmitted by a UE to a base station for channel state estimation to support uplink channel dependent scheduling and/or link adaptation. SRS transmitted by the UE may allow a base station to estimate an uplink channel state at one or more frequencies. A scheduler at the base station may employ the estimated uplink channel state to assign one or more resource blocks for an uplink PUSCH transmission from the UE. The base station may semi-statically configure the UE with one or more SRS resource sets. For an SRS resource set, the base station may configure the UE with one or more SRS resources. An SRS resource set applicability may be configured by a higher layer (e.g., RRC) parameter. For example, when a higher layer parameter indicates beam management, an SRS resource in an SRS resource set of the one or more SRS resource sets (e.g., with the same/similar time domain behavior, periodic, aperiodic, and/or the like) may be transmitted at a time instant (e.g., simultaneously). The UE may transmit one or more SRS resources in SRS resource sets. An NR network may support aperiodic, periodic and/or semi-persistent SRS transmissions. The UE may transmit SRS resources based on one or more trigger types, wherein the one or more trigger types may comprise higher layer signaling (e.g., RRC) and/or one or more DCI formats. In an example, at least one DCI format may be employed for the UE to select at least one of one or more configured SRS resource sets. An SRS trigger type 0 may refer to an SRS triggered based on a higher layer signaling. An SRS trigger type 1 may refer to an SRS triggered based on one or more DCI formats. In an example, when PUSCH and SRS are transmitted in a same slot, the UE may be configured to transmit SRS after a transmission of a PUSCH and a corresponding uplink DMRS.

The base station may semi-statically configure the UE with one or more SRS configuration parameters indicating at least one of following: a SRS resource configuration identifier; a number of SRS ports; time domain behavior of an SRS resource configuration (e.g., an indication of periodic, semi-persistent, or aperiodic SRS); slot, mini-slot, and/or subframe level periodicity; offset for a periodic and/or an aperiodic SRS resource; a number of OFDM symbols in an SRS resource; a starting OFDM symbol of an SRS resource; an SRS bandwidth; a frequency hopping bandwidth; a cyclic shift; and/or an SRS sequence ID.

An antenna port is defined such that the channel over which a symbol on the antenna port is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed. If a first symbol and a second symbol are transmitted on the same antenna port, the receiver may infer the channel (e.g., fading gain, multipath delay, and/or the like) for conveying the second symbol on the antenna port, from the channel for conveying the first symbol on the antenna port. A first antenna port and a second antenna port may be referred to as quasi co-located (QCLed) if one or more large-scale properties of the channel over which a first symbol on the first antenna port is conveyed may be inferred from the channel over which a second symbol on a second antenna port is conveyed. The one or more large-scale properties may comprise at least one of: a delay spread; a Doppler spread; a Doppler shift; an average gain; an average delay; and/or spatial Receiving (Rx) parameters.

Channels that use beamforming require beam management. Beam management may comprise beam measurement, beam selection, and beam indication. A beam may be associated with one or more reference signals. For example, a beam may be identified by one or more beamformed reference signals. The UE may perform downlink beam measurement based on downlink reference signals (e.g., a channel state information reference signal (CSI-RS)) and generate a beam measurement report. The UE may perform the downlink beam measurement procedure after an RRC connection is set up with a base station.

FIG. 11B illustrates an example of channel state information reference signals (CSI-RSs) that are mapped in the time and frequency domains. A square shown in FIG. 11B may span a resource block (RB) within a bandwidth of a cell. A base station may transmit one or more RRC messages comprising CSI-RS resource configuration parameters indicating one or more CSI-RSs. One or more of the following parameters may be configured by higher layer signaling (e.g., RRC and/or MAC signaling) for a CSI-RS resource configuration: a CSI-RS resource configuration identity, a number of CSI-RS ports, a CSI-RS configuration (e.g., symbol and resource element (RE) locations in a subframe), a CSI-RS subframe configuration (e.g., subframe location, offset, and periodicity in a radio frame), a CSI-RS power parameter, a CSI-RS sequence parameter, a code division multiplexing (CDM) type parameter, a frequency density, a transmission comb, quasi co-location (QCL) parameters (e.g., QCL-scramblingidentity, crs-portscount, mbsfn-subframeconfiglist, csi-rs-configZPid, qcl-csi-rs-configNZPid), and/or other radio resource parameters.

The three beams illustrated in FIG. 11B may be configured for a UE in a UE-specific configuration. Three beams are illustrated in FIG. 11B (beam #1, beam #2, and beam #3), more or fewer beams may be configured. Beam #1 may be allocated with CSI-RS 1101 that may be transmitted in one or more subcarriers in an RB of a first symbol. Beam #2 may be allocated with CSI-RS 1102 that may be transmitted in one or more subcarriers in an RB of a second symbol. Beam #3 may be allocated with CSI-RS 1103 that may be transmitted in one or more subcarriers in an RB of a third symbol. By using frequency division multiplexing (FDM), a base station may use other subcarriers in a same RB (for example, those that are not used to transmit CSI-RS 1101) to transmit another CSI-RS associated with a beam for another UE. By using time domain multiplexing (TDM), beams used for the UE may be configured such that beams for the UE use symbols from beams of other UEs.

CSI-RSs such as those illustrated in FIG. 11B (e.g., CSI-RS 1101, 1102, 1103) may be transmitted by the base station and used by the UE for one or more measurements. For example, the UE may measure a reference signal received power (RSRP) of configured CSI-RS resources. The base station may configure the UE with a reporting configuration and the UE may report the RSRP measurements to a network (for example, via one or more base stations) based on the reporting configuration. In an example, the base station may determine, based on the reported measurement results, one or more transmission configuration indication (TCI) states comprising a number of reference signals. In an example, the base station may indicate one or more TCI states to the UE (e.g., via RRC signaling, a MAC CE, and/or a DCI). The UE may receive a downlink transmission with a receive (Rx) beam determined based on the one or more TCI states. In an example, the UE may or may not have a capability of beam correspondence. If the UE has the capability of beam correspondence, the UE may determine a spatial domain filter of a transmit (Tx) beam based on a spatial domain filter of the corresponding Rx beam. If the UE does not have the capability of beam correspondence, the UE may perform an uplink beam selection procedure to determine the spatial domain filter of the Tx beam. The UE may perform the uplink beam selection procedure based on one or more sounding reference signal (SRS) resources configured to the UE by the base station. The base station may select and indicate uplink beams for the UE based on measurements of the one or more SRS resources transmitted by the UE.

In a beam management procedure, a UE may assess (e.g., measure) a channel quality of one or more beam pair links, a beam pair link comprising a transmitting beam transmitted by a base station and a receiving beam received by the UE. Based on the assessment, the UE may transmit a beam measurement report indicating one or more beam pair quality parameters comprising, e.g., one or more beam identifications (e.g., a beam index, a reference signal index, or the like), RSRP, a precoding matrix indicator (PMI), a channel quality indicator (CQI), and/or a rank indicator (RI).

FIG. 12A illustrates examples of three downlink beam management procedures: P1, P2, and P3. Procedure P1 may enable a UE measurement on transmit (Tx) beams of a transmission reception point (TRP) (or multiple TRPs), e.g., to support a selection of one or more base station Tx beams and/or UE Rx beams (shown as ovals in the top row and bottom row, respectively, of P1). Beamforming at a TRP may comprise a Tx beam sweep for a set of beams (shown, in the top rows of P1 and P2, as ovals rotated in a counter-clockwise direction indicated by the dashed arrow). Beamforming at a UE may comprise an Rx beam sweep for a set of beams (shown, in the bottom rows of P1 and P3, as ovals rotated in a clockwise direction indicated by the dashed arrow). Procedure P2 may be used to enable a UE measurement on Tx beams of a TRP (shown, in the top row of P2, as ovals rotated in a counter-clockwise direction indicated by the dashed arrow). The UE and/or the base station may perform procedure P2 using a smaller set of beams than is used in procedure P1, or using narrower beams than the beams used in procedure P1. This may be referred to as beam refinement. The UE may perform procedure P3 for Rx beam determination by using the same Tx beam at the base station and sweeping an Rx beam at the UE.

FIG. 12B illustrates examples of three uplink beam management procedures: U1, U2, and U3. Procedure U1 may be used to enable a base station to perform a measurement on Tx beams of a UE, e.g., to support a selection of one or more UE Tx beams and/or base station Rx beams (shown as ovals in the top row and bottom row, respectively, of U1). Beamforming at the UE may include, e.g., a Tx beam sweep from a set of beams (shown in the bottom rows of U1 and U3 as ovals rotated in a clockwise direction indicated by the dashed arrow). Beamforming at the base station may include, e.g., an Rx beam sweep from a set of beams (shown, in the top rows of U1 and U2, as ovals rotated in a counter-clockwise direction indicated by the dashed arrow). Procedure U2 may be used to enable the base station to adjust its Rx beam when the UE uses a fixed Tx beam. The UE and/or the base station may perform procedure U2 using a smaller set of beams than is used in procedure P1, or using narrower beams than the beams used in procedure P1. This may be referred to as beam refinement The UE may perform procedure U3 to adjust its Tx beam when the base station uses a fixed Rx beam.

A UE may initiate a beam failure recovery (BFR) procedure based on detecting a beam failure. The UE may transmit a BFR request (e.g., a preamble, a UCI, an SR, a MAC CE, and/or the like) based on the initiating of the BFR procedure. The UE may detect the beam failure based on a determination that a quality of beam pair link(s) of an associated control channel is unsatisfactory (e.g., having an error rate higher than an error rate threshold, a received signal power lower than a received signal power threshold, an expiration of a timer, and/or the like).

The UE may measure a quality of a beam pair link using one or more reference signals (RSs) comprising one or more SS/PBCH blocks, one or more CSI-RS resources, and/or one or more demodulation reference signals (DMRSs). A quality of the beam pair link may be based on one or more of a block error rate (BLER), an RSRP value, a signal to interference plus noise ratio (SINR) value, a reference signal received quality (RSRQ) value, and/or a CSI value measured on RS resources. The base station may indicate that an RS resource is quasi co-located (QCLed) with one or more DM-RSs of a channel (e.g., a control channel, a shared data channel, and/or the like). The RS resource and the one or more DMRSs of the channel may be QCLed when the channel characteristics (e.g., Doppler shift, Doppler spread, average delay, delay spread, spatial Rx parameter, fading, and/or the like) from a transmission via the RS resource to the UE are similar or the same as the channel characteristics from a transmission via the channel to the UE.

A network (e.g., a gNB and/or an ng-eNB of a network) and/or the UE may initiate a random access procedure. A UE in an RRC_IDLE state and/or an RRC_INACTIVE state may initiate the random access procedure to request a connection setup to a network. The UE may initiate the random access procedure from an RRC_CONNECTED state. The UE may initiate the random access procedure to request uplink resources (e.g., for uplink transmission of an SR when there is no PUCCH resource available) and/or acquire uplink timing (e.g., when uplink synchronization status is non-synchronized). The UE may initiate the random access procedure to request one or more system information blocks (SIBs) (e.g., other system information such as SIB2, SIB3, and/or the like). The UE may initiate the random access procedure for a beam failure recovery request. A network may initiate a random access procedure for a handover and/or for establishing time alignment for an SCell addition.

FIG. 13A illustrates a four-step contention-based random access procedure. Prior to initiation of the procedure, a base station may transmit a configuration message 1310 to the UE. The procedure illustrated in FIG. 13A comprises transmission of four messages: a Msg 1 1311, a Msg 2 1312, a Msg 3 1313, and a Msg 4 1314. The Msg 1 1311 may include and/or be referred to as a preamble (or a random access preamble). The Msg 2 1312 may include and/or be referred to as a random access response (RAR).

The configuration message 1310 may be transmitted, for example, using one or more RRC messages. The one or more RRC messages may indicate one or more random access channel (RACH) parameters to the UE. The one or more RACH parameters may comprise at least one of following: general parameters for one or more random access procedures (e.g., RACH-configGeneral); cell-specific parameters (e.g., RACH-ConfigCommon); and/or dedicated parameters (e.g., RACH-configDedicated). The base station may broadcast or multicast the one or more RRC messages to one or more UEs. The one or more RRC messages may be UE-specific (e.g., dedicated RRC messages transmitted to a UE in an RRC_CONNECTED state and/or in an RRC_INACTIVE state). The UE may determine, based on the one or more RACH parameters, a time-frequency resource and/or an uplink transmit power for transmission of the Msg 1 1311 and/or the Msg 3 1313. Based on the one or more RACH parameters, the UE may determine a reception timing and a downlink channel for receiving the Msg 2 1312 and the Msg 4 1314.

The one or more RACH parameters provided in the configuration message 1310 may indicate one or more Physical RACH (PRACH) occasions available for transmission of the Msg 1 1311. The one or more PRACH occasions may be predefined. The one or more RACH parameters may indicate one or more available sets of one or more PRACH occasions (e.g., prach-ConfigIndex). The one or more RACH parameters may indicate an association between (a) one or more PRACH occasions and (b) one or more reference signals. The one or more RACH parameters may indicate an association between (a) one or more preambles and (b) one or more reference signals. The one or more reference signals may be SS/PBCH blocks and/or CSI-RSs. For example, the one or more RACH parameters may indicate a number of SS/PBCH blocks mapped to a PRACH occasion and/or a number of preambles mapped to a SS/PBCH blocks.

The one or more RACH parameters provided in the configuration message 1310 may be used to determine an uplink transmit power of Msg 1 1311 and/or Msg 3 1313. For example, the one or more RACH parameters may indicate a reference power for a preamble transmission (e.g., a received target power and/or an initial power of the preamble transmission). There may be one or more power offsets indicated by the one or more RACH parameters. For example, the one or more RACH parameters may indicate: a power ramping step; a power offset between SSB and CSI-RS; a power offset between transmissions of the Msg 1 1311 and the Msg 3 1313; and/or a power offset value between preamble groups. The one or more RACH parameters may indicate one or more thresholds based on which the UE may determine at least one reference signal (e.g., an SSB and/or CSI-RS) and/or an uplink carrier (e.g., a normal uplink (NUL) carrier and/or a supplemental uplink (SUL) carrier).

The Msg 1 1311 may include one or more preamble transmissions (e.g., a preamble transmission and one or more preamble retransmissions). An RRC message may be used to configure one or more preamble groups (e.g., group A and/or group B). A preamble group may comprise one or more preambles. The UE may determine the preamble group based on a pathloss measurement and/or a size of the Msg 3 1313. The UE may measure an RSRP of one or more reference signals (e.g., SSBs and/or CSI-RSs) and determine at least one reference signal having an RSRP above an RSRP threshold (e.g., rsrp-ThresholdSSB and/or rsrp-ThresholdCSI-RS). The UE may select at least one preamble associated with the one or more reference signals and/or a selected preamble group, for example, if the association between the one or more preambles and the at least one reference signal is configured by an RRC message.

The UE may determine the preamble based on the one or more RACH parameters provided in the configuration message 1310. For example, the UE may determine the preamble based on a pathloss measurement, an RSRP measurement, and/or a size of the Msg 3 1313. As another example, the one or more RACH parameters may indicate: a preamble format; a maximum number of preamble transmissions; and/or one or more thresholds for determining one or more preamble groups (e.g., group A and group B). A base station may use the one or more RACH parameters to configure the UE with an association between one or more preambles and one or more reference signals (e.g., SSBs and/or CSI-RSs). If the association is configured, the UE may determine the preamble to include in Msg 1 1311 based on the association. The Msg 1 1311 may be transmitted to the base station via one or more PRACH occasions. The UE may use one or more reference signals (e.g., SSBs and/or CSI-RSs) for selection of the preamble and for determining of the PRACH occasion. One or more RACH parameters (e.g., ra-ssb-OccasionMskIndex and/or ra-OccasionList) may indicate an association between the PRACH occasions and the one or more reference signals.

The UE may perform a preamble retransmission if no response is received following a preamble transmission. The UE may increase an uplink transmit power for the preamble retransmission. The UE may select an initial preamble transmit power based on a pathloss measurement and/or a target received preamble power configured by the network. The UE may determine to retransmit a preamble and may ramp up the uplink transmit power. The UE may receive one or more RACH parameters (e.g., PREAMBLE_POWER_RAMPING_STEP) indicating a ramping step for the preamble retransmission. The ramping step may be an amount of incremental increase in uplink transmit power for a retransmission. The UE may ramp up the uplink transmit power if the UE determines a reference signal (e.g., SSB and/or CSI-RS) that is the same as a previous preamble transmission. The UE may count a number of preamble transmissions and/or retransmissions (e.g., PREAMBLE_TRANSMISSION_COUNTER). The UE may determine that a random access procedure completed unsuccessfully, for example, if the number of preamble transmissions exceeds a threshold configured by the one or more RACH parameters (e.g., preamble TransMax).

The Msg 2 1312 received by the UE may include an RAR. In some scenarios, the Msg 2 1312 may include multiple RARs corresponding to multiple UEs. The Msg 2 1312 may be received after or in response to the transmitting of the Msg 1 1311. The Msg 2 1312 may be scheduled on the DL-SCH and indicated on a PDCCH using a random access RNTI (RA-RNTI). The Msg 2 1312 may indicate that the Msg 1 1311 was received by the base station. The Msg 2 1312 may include a time-alignment command that may be used by the UE to adjust the UE's transmission timing, a scheduling grant for transmission of the Msg 3 1313, and/or a Temporary Cell RNTI (TC-RNTI). After transmitting a preamble, the UE may start a time window (e.g., ra-ResponseWindow) to monitor a PDCCH for the Msg 2 1312. The UE may determine when to start the time window based on a PRACH occasion that the UE uses to transmit the preamble. For example, the UE may start the time window one or more symbols after a last symbol of the preamble (e.g., at a first PDCCH occasion from an end of a preamble transmission). The one or more symbols may be determined based on a numerology. The PDCCH may be in a common search space (e.g., a Type1-PDCCH common search space) configured by an RRC message. The UE may identify the RAR based on a Radio Network Temporary Identifier (RNTI). RNTIs may be used depending on one or more events initiating the random access procedure. The UE may use random access RNTI (RA-RNTI). The RA-RNTI may be associated with PRACH occasions in which the UE transmits a preamble. For example, the UE may determine the RA-RNTI based on: an OFDM symbol index; a slot index; a frequency domain index; and/or a UL carrier indicator of the PRACH occasions. An example of RA-RNTI may be as follows:

$\mathrm{RA}-\mathrm{RNTI}=1+\mathrm{s\_id}+14\times \mathrm{t\_id}+14\times 80\times \mathrm{f\_id}+14\times 80\times 8\times \mathrm{ul\_carrier}\mathrm{\_id}$

where s_id may be an index of a first OFDM symbol of the PRACH occasion (e.g., 0≤s_id<14), t_id may be an index of a first slot of the PRACH occasion in a system frame (e.g., 0≤t_id<80), f_id may be an index of the PRACH occasion in the frequency domain (e.g., 0≤f_id<8), and ul_carrier_id may be a UL carrier used for a preamble transmission (e.g., 0 for an NUL carrier, and 1 for an SUL carrier).

The UE may transmit the Msg 3 1313 in response to a successful reception of the Msg 2 1312 (e.g., using resources identified in the Msg 2 1312). The Msg 3 1313 may be used for contention resolution in, for example, the contention-based random access procedure illustrated in FIG. 13A. In some scenarios, a plurality of UEs may transmit a same preamble to a base station and the base station may provide an RAR that corresponds to a UE. Collisions may occur if the plurality of UEs interpret the RAR as corresponding to themselves. Contention resolution (e.g., using the Msg 3 1313 and the Msg 4 1314) may be used to increase the likelihood that the UE does not incorrectly use an identity of another the UE. To perform contention resolution, the UE may include a device identifier in the Msg 3 1313 (e.g., a C-RNTI if assigned, a TC-RNTI included in the Msg 2 1312, and/or any other suitable identifier).

The Msg 4 1314 may be received after or in response to the transmitting of the Msg 3 1313. If a C-RNTI was included in the Msg 3 1313, the base station will address the UE on the PDCCH using the C-RNTI. If the UE's unique C-RNTI is detected on the PDCCH, the random access procedure is determined to be successfully completed. If a TC-RNTI is included in the Msg 3 1313 (e.g., if the UE is in an RRC_IDLE state or not otherwise connected to the base station), Msg 4 1314 will be received using a DL-SCH associated with the TC-RNTI. If a MAC PDU is successfully decoded and a MAC PDU comprises the UE contention resolution identity MAC CE that matches or otherwise corresponds with the CCCH SDU sent (e.g., transmitted) in Msg 3 1313, the UE may determine that the contention resolution is successful and/or the UE may determine that the random access procedure is successfully completed.

The UE may be configured with a supplementary uplink (SUL) carrier and a normal uplink (NUL) carrier. An initial access (e.g., random access procedure) may be supported in an uplink carrier. For example, a base station may configure the UE with two separate RACH configurations: one for an SUL carrier and the other for an NUL carrier. For random access in a cell configured with an SUL carrier, the network may indicate which carrier to use (NUL or SUL). The UE may determine the SUL carrier, for example, if a measured quality of one or more reference signals is lower than a broadcast threshold. Uplink transmissions of the random access procedure (e.g., the Msg 1 1311 and/or the Msg 3 1313) may remain on the selected carrier. The UE may switch an uplink carrier during the random access procedure (e.g., between the Msg 1 1311 and the Msg 3 1313) in one or more cases. For example, the UE may determine and/or switch an uplink carrier for the Msg 1 1311 and/or the Msg 3 1313 based on a channel clear assessment (e.g., a listen-before-talk).

FIG. 13B illustrates a two-step contention-free random access procedure. Similar to the four-step contention-based random access procedure illustrated in FIG. 13A, a base station may, prior to initiation of the procedure, transmit a configuration message 1320 to the UE. The configuration message 1320 may be analogous in some respects to the configuration message 1310. The procedure illustrated in FIG. 13B comprises transmission of two messages: a Msg 1 1321 and a Msg 2 1322. The Msg 1 1321 and the Msg 2 1322 may be analogous in some respects to the Msg 1 1311 and a Msg 2 1312 illustrated in FIG. 13A, respectively. As will be understood from FIGS. 13A and 13B, the contention-free random access procedure may not include messages analogous to the Msg 3 1313 and/or the Msg 4 1314.

The contention-free random access procedure illustrated in FIG. 13B may be initiated for a beam failure recovery, other SI request, SCell addition, and/or handover. For example, a base station may indicate or assign to the UE the preamble to be used for the Msg 1 1321. The UE may receive, from the base station via PDCCH and/or RRC, an indication of a preamble (e.g., ra-PreambleIndex).

After transmitting a preamble, the UE may start a time window (e.g., ra-ResponseWindow) to monitor a PDCCH for the RAR. In the event of a beam failure recovery request, the base station may configure the UE with a separate time window and/or a separate PDCCH in a search space indicated by an RRC message (e.g., recoverySearchSpaceId). The UE may monitor for a PDCCH transmission addressed to a Cell RNTI (C-RNTI) on the search space. In the contention-free random access procedure illustrated in FIG. 13B, the UE may determine that a random access procedure successfully completes after or in response to transmission of Msg 1 1321 and reception of a corresponding Msg 2 1322. The UE may determine that a random access procedure successfully completes, for example, if a PDCCH transmission is addressed to a C-RNTI. The UE may determine that a random access procedure successfully completes, for example, if the UE receives an RAR comprising a preamble identifier corresponding to a preamble transmitted by the UE and/or the RAR comprises a MAC sub-PDU with the preamble identifier. The UE may determine the response as an indication of an acknowledgement for an SI request.

FIG. 13C illustrates another two-step random access procedure. Similar to the random access procedures illustrated in FIGS. 13A and 13B, a base station may, prior to initiation of the procedure, transmit a configuration message 1330 to the UE. The configuration message 1330 may be analogous in some respects to the configuration message 1310 and/or the configuration message 1320. The procedure illustrated in FIG. 13C comprises transmission of two messages: a Msg A 1331 and a Msg B 1332.

Msg A 1331 may be transmitted in an uplink transmission by the UE. Msg A 1331 may comprise one or more transmissions of a preamble 1341 and/or one or more transmissions of a transport block 1342. The transport block 1342 may comprise contents that are similar and/or equivalent to the contents of the Msg 3 1313 illustrated in FIG. 13A. The transport block 1342 may comprise UCI (e.g., an SR, a HARQ ACK/NACK, and/or the like). The UE may receive the Msg B 1332 after or in response to transmitting the Msg A 1331. The Msg B 1332 may comprise contents that are similar and/or equivalent to the contents of the Msg 2 1312 (e.g., an RAR) illustrated in FIGS. 13A and 13B and/or the Msg 4 1314 illustrated in FIG. 13A.

The UE may initiate the two-step random access procedure in FIG. 13C for licensed spectrum and/or unlicensed spectrum. The UE may determine, based on one or more factors, whether to initiate the two-step random access procedure. The one or more factors may be: a radio access technology in use (e.g., LTE, NR, and/or the like); whether the UE has valid TA or not; a cell size; the UE's RRC state; a type of spectrum (e.g., licensed vs. unlicensed); and/or any other suitable factors.

The UE may determine, based on two-step RACH parameters included in the configuration message 1330, a radio resource and/or an uplink transmit power for the preamble 1341 and/or the transport block 1342 included in the Msg A 1331. The RACH parameters may indicate a modulation and coding schemes (MCS), a time-frequency resource, and/or a power control for the preamble 1341 and/or the transport block 1342. A time-frequency resource for transmission of the preamble 1341 (e.g., a PRACH) and a time-frequency resource for transmission of the transport block 1342 (e.g., a PUSCH) may be multiplexed using FDM, TDM, and/or CDM. The RACH parameters may enable the UE to determine a reception timing and a downlink channel for monitoring for and/or receiving Msg B 1332.

The transport block 1342 may comprise data (e.g., delay-sensitive data), an identifier of the UE, security information, and/or device information (e.g., an International Mobile Subscriber Identity (IMSI). The base station may transmit the Msg B 1332 as a response to the Msg A 1331. The Msg B 1332 may comprise at least one of following: a preamble identifier; a timing advance command; a power control command; an uplink grant (e.g., a radio resource assignment and/or an MCS); a UE identifier for contention resolution; and/or an RNTI (e.g., a C-RNTI or a TC-RNTI). The UE may determine that the two-step random access procedure is successfully completed if: a preamble identifier in the Msg B 1332 is matched to a preamble transmitted by the UE; and/or the identifier of the UE in Msg B 1332 is matched to the identifier of the UE in the Msg A 1331 (e.g., the transport block 1342).

A UE and a base station may exchange control signaling. The control signaling may be referred to as L1/L2 control signaling and may originate from the PHY layer (e.g., layer 1) and/or the MAC layer (e.g., layer 2). The control signaling may comprise downlink control signaling transmitted from the base station to the UE and/or uplink control signaling transmitted from the UE to the base station.

The downlink control signaling may comprise: a downlink scheduling assignment; an uplink scheduling grant indicating uplink radio resources and/or a transport format; a slot format information; a preemption indication; a power control command; and/or any other suitable signaling. The UE may receive the downlink control signaling in a payload transmitted by the base station on a physical downlink control channel (PDCCH). The payload transmitted on the PDCCH may be referred to as downlink control information (DCI). In some scenarios, the PDCCH may be a group common PDCCH (GC-PDCCH) that is common to a group of UEs.

A base station may attach one or more cyclic redundancy check (CRC) parity bits to a DCI in order to facilitate detection of transmission errors. When the DCI is intended for a UE (or a group of the UEs), the base station may scramble the CRC parity bits with an identifier of the UE (or an identifier of the group of the UEs). Scrambling the CRC parity bits with the identifier may comprise Modulo-2 addition (or an exclusive OR operation) of the identifier value and the CRC parity bits. The identifier may comprise a 16-bit value of a radio network temporary identifier (RNTI).

DCIs may be used for different purposes. A purpose may be indicated by the type of RNTI used to scramble the CRC parity bits. For example, a DCI having CRC parity bits scrambled with a paging RNTI (P-RNTI) may indicate paging information and/or a system information change notification. The P-RNTI may be predefined as “FFFE” in hexadecimal. A DCI having CRC parity bits scrambled with a system information RNTI (SI-RNTI) may indicate a broadcast transmission of the system information. The SI-RNTI may be predefined as “FFFF” in hexadecimal. A DCI having CRC parity bits scrambled with a random access RNTI (RA-RNTI) may indicate a random access response (RAR). A DCI having CRC parity bits scrambled with a cell RNTI (C-RNTI) may indicate a dynamically scheduled unicast transmission and/or a triggering of PDCCH-ordered random access. A DCI having CRC parity bits scrambled with a temporary cell RNTI (TC-RNTI) may indicate a contention resolution (e.g., a Msg 3 analogous to the Msg 3 1313 illustrated in FIG. 13A). Other RNTIs configured to the UE by a base station may comprise a Configured Scheduling RNTI (CS-RNTI), a Transmit Power Control-PUCCH RNTI (TPC-PUCCH-RNTI), a Transmit Power Control-PUSCH RNTI (TPC-PUSCH-RNTI), a Transmit Power Control-SRS RNTI (TPC-SRS-RNTI), an Interruption RNTI (INT-RNTI), a Slot Format Indication RNTI (SFI-RNTI), a Semi-Persistent CSI RNTI (SP-CSI-RNTI), a Modulation and Coding Scheme Cell RNTI (MCS-C-RNTI), and/or the like.

Depending on the purpose and/or content of a DCI, the base station may transmit the DCIs with one or more DCI formats. For example, DCI format 0_0 may be used for scheduling of PUSCH in a cell. DCI format 0_0 may be a fallback DCI format (e.g., with compact DCI payloads). DCI format 0_1 may be used for scheduling of PUSCH in a cell (e.g., with more DCI payloads than DCI format 0_0). DCI format 1_0 may be used for scheduling of PDSCH in a cell. DCI format 1_0 may be a fallback DCI format (e.g., with compact DCI payloads). DCI format 1_1 may be used for scheduling of PDSCH in a cell (e.g., with more DCI payloads than DCI format 1_0). DCI format 2_0 may be used for providing a slot format indication to a group of UEs. DCI format 2_1 may be used for notifying a group of UEs of a physical resource block and/or OFDM symbol where the UE may assume no transmission is intended to the UE. DCI format 2_2 may be used for transmission of a transmit power control (TPC) command for PUCCH or PUSCH. DCI format 2_3 may be used for transmission of a group of TPC commands for SRS transmissions by one or more UEs. DCI format(s) for new functions may be defined in future releases. DCI formats may have different DCI sizes, or may share the same DCI size.

After scrambling a DCI with a RNTI, the base station may process the DCI with channel coding (e.g., polar coding), rate matching, scrambling and/or QPSK modulation. A base station may map the coded and modulated DCI on resource elements used and/or configured for a PDCCH. Based on a payload size of the DCI and/or a coverage of the base station, the base station may transmit the DCI via a PDCCH occupying a number of contiguous control channel elements (CCEs). The number of the contiguous CCEs (referred to as aggregation level) may be 1, 2, 4, 8, 16, and/or any other suitable number. A CCE may comprise a number (e.g., 6) of resource-element groups (REGs). A REG may comprise a resource block in an OFDM symbol. The mapping of the coded and modulated DCI on the resource elements may be based on mapping of CCEs and REGs (e.g., CCE-to-REG mapping).

FIG. 14A illustrates an example of CORESET configurations for a bandwidth part. The base station may transmit a DCI via a PDCCH on one or more control resource sets (CORESETs). A CORESET may comprise a time-frequency resource in which the UE tries to decode a DCI using one or more search spaces. The base station may configure a CORESET in the time-frequency domain. In the example of FIG. 14A, a first CORESET 1401 and a second CORESET 1402 occur at the first symbol in a slot. The first CORESET 1401 overlaps with the second CORESET 1402 in the frequency domain. A third CORESET 1403 occurs at a third symbol in the slot. A fourth CORESET 1404 occurs at the seventh symbol in the slot. CORESETs may have a different number of resource blocks in frequency domain.

FIG. 14B illustrates an example of a CCE-to-REG mapping for DCI transmission on a CORESET and PDCCH processing. The CCE-to-REG mapping may be an interleaved mapping (e.g., for the purpose of providing frequency diversity) or a non-interleaved mapping (e.g., for the purposes of facilitating interference coordination and/or frequency-selective transmission of control channels). The base station may perform different or same CCE-to-REG mapping on different CORESETs. A CORESET may be associated with a CCE-to-REG mapping by RRC configuration. A CORESET may be configured with an antenna port quasi co-location (QCL) parameter. The antenna port QCL parameter may indicate QCL information of a demodulation reference signal (DMRS) for PDCCH reception in the CORESET.

The base station may transmit, to the UE, RRC messages comprising configuration parameters of one or more CORESETs and one or more search space sets. The configuration parameters may indicate an association between a search space set and a CORESET. A search space set may comprise a set of PDCCH candidates formed by CCEs at a given aggregation level. The configuration parameters may indicate: a number of PDCCH candidates to be monitored per aggregation level; a PDCCH monitoring periodicity and a PDCCH monitoring pattern; one or more DCI formats to be monitored by the UE; and/or whether a search space set is a common search space set or a UE-specific search space set. A set of CCEs in the common search space set may be predefined and known to the UE. A set of CCEs in the UE-specific search space set may be configured based on the UE's identity (e.g., C-RNTI).

As shown in FIG. 14B, the UE may determine a time-frequency resource for a CORESET based on RRC messages. The UE may determine a CCE-to-REG mapping (e.g., interleaved or non-interleaved, and/or mapping parameters) for the CORESET based on configuration parameters of the CORESET. The UE may determine a number (e.g., at most 10) of search space sets configured on the CORESET based on the RRC messages. The UE may monitor a set of PDCCH candidates according to configuration parameters of a search space set. The UE may monitor a set of PDCCH candidates in one or more CORESETs for detecting one or more DCIs. Monitoring may comprise decoding one or more PDCCH candidates of the set of the PDCCH candidates according to the monitored DCI formats. Monitoring may comprise decoding a DCI content of one or more PDCCH candidates with possible (or configured) PDCCH locations, possible (or configured) PDCCH formats (e.g., number of CCEs, number of PDCCH candidates in common search spaces, and/or number of PDCCH candidates in the UE-specific search spaces) and possible (or configured) DCI formats. The decoding may be referred to as blind decoding. The UE may determine a DCI as valid for the UE, in response to CRC checking (e.g., scrambled bits for CRC parity bits of the DCI matching a RNTI value). The UE may process information contained in the DCI (e.g., a scheduling assignment, an uplink grant, power control, a slot format indication, a downlink preemption, and/or the like).

The UE may transmit uplink control signaling (e.g., uplink control information (UCI)) to a base station. The uplink control signaling may comprise hybrid automatic repeat request (HARQ) acknowledgements for received DL-SCH transport blocks. The UE may transmit the HARQ acknowledgements after receiving a DL-SCH transport block. Uplink control signaling may comprise channel state information (CSI) indicating channel quality of a physical downlink channel. The UE may transmit the CSI to the base station. The base station, based on the received CSI, may determine transmission format parameters (e.g., comprising multi-antenna and beamforming schemes) for a downlink transmission. Uplink control signaling may comprise scheduling requests (SR). The UE may transmit an SR indicating that uplink data is available for transmission to the base station. The UE may transmit a UCI (e.g., HARQ acknowledgements (HARQ-ACK), CSI report, SR, and the like) via a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH). The UE may transmit the uplink control signaling via a PUCCH using one of several PUCCH formats.

There may be five PUCCH formats and the UE may determine a PUCCH format based on a size of the UCI (e.g., a number of uplink symbols of UCI transmission and a number of UCI bits). PUCCH format 0 may have a length of one or two OFDM symbols and may include two or fewer bits. The UE may transmit UCI in a PUCCH resource using PUCCH format 0 if the transmission is over one or two symbols and the number of HARQ-ACK information bits with positive or negative SR (HARQ-ACK/SR bits) is one or two. PUCCH format 1 may occupy a number between four and fourteen OFDM symbols and may include two or fewer bits. The UE may use PUCCH format 1 if the transmission is four or more symbols and the number of HARQ-ACK/SR bits is one or two. PUCCH format 2 may occupy one or two OFDM symbols and may include more than two bits. The UE may use PUCCH format 2 if the transmission is over one or two symbols and the number of UCI bits is two or more. PUCCH format 3 may occupy a number between four and fourteen OFDM symbols and may include more than two bits. The UE may use PUCCH format 3 if the transmission is four or more symbols, the number of UCI bits is two or more and PUCCH resource does not include an orthogonal cover code. PUCCH format 4 may occupy a number between four and fourteen OFDM symbols and may include more than two bits. The UE may use PUCCH format 4 if the transmission is four or more symbols, the number of UCI bits is two or more and the PUCCH resource includes an orthogonal cover code.

The base station may transmit configuration parameters to the UE for a plurality of PUCCH resource sets using, for example, an RRC message. The plurality of PUCCH resource sets (e.g., up to four sets) may be configured on an uplink BWP of a cell. A PUCCH resource set may be configured with a PUCCH resource set index, a plurality of PUCCH resources with a PUCCH resource being identified by a PUCCH resource identifier (e.g., pucch-Resourceid), and/or a number (e.g. a maximum number) of UCI information bits the UE may transmit using one of the plurality of PUCCH resources in the PUCCH resource set. When configured with a plurality of PUCCH resource sets, the UE may select one of the plurality of PUCCH resource sets based on a total bit length of the UCI information bits (e.g., HARQ-ACK, SR, and/or CSI). If the total bit length of UCI information bits is two or fewer, the UE may select a first PUCCH resource set having a PUCCH resource set index equal to “0”. If the total bit length of UCI information bits is greater than two and less than or equal to a first configured value, the UE may select a second PUCCH resource set having a PUCCH resource set index equal to “1”. If the total bit length of UCI information bits is greater than the first configured value and less than or equal to a second configured value, the UE may select a third PUCCH resource set having a PUCCH resource set index equal to “2”. If the total bit length of UCI information bits is greater than the second configured value and less than or equal to a third value (e.g., 1406), the UE may select a fourth PUCCH resource set having a PUCCH resource set index equal to “3”.

After determining a PUCCH resource set from a plurality of PUCCH resource sets, the UE may determine a PUCCH resource from the PUCCH resource set for UCI (HARQ-ACK, CSI, and/or SR) transmission. The UE may determine the PUCCH resource based on a PUCCH resource indicator in a DCI (e.g., with a DCI format 1_0 or DCI for 1_1) received on a PDCCH. A three-bit PUCCH resource indicator in the DCI may indicate one of eight PUCCH resources in the PUCCH resource set. Based on the PUCCH resource indicator, the UE may transmit the UCI (HARQ-ACK, CSI and/or SR) using a PUCCH resource indicated by the PUCCH resource indicator in the DCI.

FIG. 15 illustrates an example of a wireless device 1502 in communication with a base station 1504 in accordance with embodiments of the present disclosure. The wireless device 1502 and base station 1504 may be part of a mobile communication network, such as the mobile communication network 100 illustrated in FIG. 1A, the mobile communication network 150 illustrated in FIG. 1B, or any other communication network. Only one wireless device 1502 and one base station 1504 are illustrated in FIG. 15, but it will be understood that a mobile communication network may include more than one UE and/or more than one base station, with the same or similar configuration as those shown in FIG. 15.

The base station 1504 may connect the wireless device 1502 to a core network (not shown) through radio communications over the air interface (or radio interface) 1506. The communication direction from the base station 1504 to the wireless device 1502 over the air interface 1506 is known as the downlink, and the communication direction from the wireless device 1502 to the base station 1504 over the air interface is known as the uplink. Downlink transmissions may be separated from uplink transmissions using FDD, TDD, and/or some combination of the two duplexing techniques.

In the downlink, data to be sent to the wireless device 1502 from the base station 1504 may be provided to the processing system 1508 of the base station 1504. The data may be provided to the processing system 1508 by, for example, a core network. In the uplink, data to be sent to the base station 1504 from the wireless device 1502 may be provided to the processing system 1518 of the wireless device 1502. The processing system 1508 and the processing system 1518 may implement layer 3 and layer 2 OSI functionality to process the data for transmission. Layer 2 may include an SDAP layer, a PDCP layer, an RLC layer, and a MAC layer, for example, with respect to FIG. 2A, FIG. 2B, FIG. 3, and FIG. 4A. Layer 3 may include an RRC layer as with respect to FIG. 2B.

After being processed by processing system 1508, the data to be sent to the wireless device 1502 may be provided to a transmission processing system 1510 of base station 1504. Similarly, after being processed by the processing system 1518, the data to be sent to base station 1504 may be provided to a transmission processing system 1520 of the wireless device 1502. The transmission processing system 1510 and the transmission processing system 1520 may implement layer 1 OSI functionality. Layer 1 may include a PHY layer with respect to FIG. 2A, FIG. 2B, FIG. 3, and FIG. 4A. For transmit processing, the PHY layer may perform, for example, forward error correction coding of transport channels, interleaving, rate matching, mapping of transport channels to physical channels, modulation of physical channel, multiple-input multiple-output (MIMO) or multi-antenna processing, and/or the like.

At the base station 1504, a reception processing system 1512 may receive the uplink transmission from the wireless device 1502. At the wireless device 1502, a reception processing system 1522 may receive the downlink transmission from base station 1504. The reception processing system 1512 and the reception processing system 1522 may implement layer 1 OSI functionality. Layer 1 may include a PHY layer with respect to FIG. 2A, FIG. 2B, FIG. 3, and FIG. 4A. For receive processing, the PHY layer may perform, for example, error detection, forward error correction decoding, deinterleaving, demapping of transport channels to physical channels, demodulation of physical channels, MIMO or multi-antenna processing, and/or the like.

As shown in FIG. 15, a wireless device 1502 and the base station 1504 may include multiple antennas. The multiple antennas may be used to perform one or more MIMO or multi-antenna techniques, such as spatial multiplexing (e.g., single-user MIMO or multi-user MIMO), transmit/receive diversity, and/or beamforming. In other examples, the wireless device 1502 and/or the base station 1504 may have a single antenna.

The processing system 1508 and the processing system 1518 may be associated with a memory 1514 and a memory 1524, respectively. Memory 1514 and memory 1524 (e.g., one or more non-transitory computer readable mediums) may store computer program instructions or code that may be executed by the processing system 1508 and/or the processing system 1518 to carry out one or more of the functionalities discussed in the present application. Although not shown in FIG. 15, the transmission processing system 1510, the transmission processing system 1520, the reception processing system 1512, and/or the reception processing system 1522 may be coupled to a memory (e.g., one or more non-transitory computer readable mediums) storing computer program instructions or code that may be executed to carry out one or more of their respective functionalities.

The processing system 1508 and/or the processing system 1518 may comprise one or more controllers and/or one or more processors. The one or more controllers and/or one or more processors may comprise, for example, a general-purpose processor, a digital signal processor (DSP), a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) and/or other programmable logic device, discrete gate and/or transistor logic, discrete hardware components, an on-board unit, or any combination thereof. The processing system 1508 and/or the processing system 1518 may perform at least one of signal coding/processing, data processing, power control, input/output processing, and/or any other functionality that may enable the wireless device 1502 and the base station 1504 to operate in a wireless environment.

The processing system 1508 and/or the processing system 1518 may be connected to one or more peripherals 1516 and one or more peripherals 1526, respectively. The one or more peripherals 1516 and the one or more peripherals 1526 may include software and/or hardware that provide features and/or functionalities, for example, a speaker, a microphone, a keypad, a display, a touchpad, a power source, a satellite transceiver, a universal serial bus (USB) port, a hands-free headset, a frequency modulated (FM) radio unit, a media player, an Internet browser, an electronic control unit (e.g., for a motor vehicle), and/or one or more sensors (e.g., an accelerometer, a gyroscope, a temperature sensor, a radar sensor, a lidar sensor, an ultrasonic sensor, a light sensor, a camera, and/or the like). The processing system 1508 and/or the processing system 1518 may receive user input data from and/or provide user output data to the one or more peripherals 1516 and/or the one or more peripherals 1526. The processing system 1518 in the wireless device 1502 may receive power from a power source and/or may be configured to distribute the power to the other components in the wireless device 1502. The power source may comprise one or more sources of power, for example, a battery, a solar cell, a fuel cell, or any combination thereof. The processing system 1508 and/or the processing system 1518 may be connected to a GPS chipset 1517 and a GPS chipset 1527, respectively. The GPS chipset 1517 and the GPS chipset 1527 may be configured to provide geographic location information of the wireless device 1502 and the base station 1504, respectively.

FIG. 16A illustrates an example structure for uplink transmission. A baseband signal representing a physical uplink shared channel may perform one or more functions. The one or more functions may comprise at least one of: scrambling; modulation of scrambled bits to generate complex-valued symbols; mapping of the complex-valued modulation symbols onto one or several transmission layers; transform precoding to generate complex-valued symbols; precoding of the complex-valued symbols; mapping of precoded complex-valued symbols to resource elements; generation of complex-valued time-domain Single Carrier-Frequency Division Multiple Access (SC-FDMA) or CP-OFDM signal for an antenna port; and/or the like. In an example, when transform precoding is enabled, a SC-FDMA signal for uplink transmission may be generated. In an example, when transform precoding is not enabled, a CP-OFDM signal for uplink transmission may be generated by FIG. 16A. These functions are illustrated as examples and it is anticipated that other mechanisms may be implemented in various embodiments.

FIG. 16B illustrates an example structure for modulation and up-conversion of a baseband signal to a carrier frequency. The baseband signal may be a complex-valued SC-FDMA or CP-OFDM baseband signal for an antenna port and/or a complex-valued Physical Random Access Channel (PRACH) baseband signal. Filtering may be employed prior to transmission.

FIG. 16C illustrates an example structure for downlink transmissions. A baseband signal representing a physical downlink channel may perform one or more functions. The one or more functions may comprise: scrambling of coded bits in a codeword to be transmitted on a physical channel; modulation of scrambled bits to generate complex-valued modulation symbols; mapping of the complex-valued modulation symbols onto one or several transmission layers; precoding of the complex-valued modulation symbols on a layer for transmission on the antenna ports; mapping of complex-valued modulation symbols for an antenna port to resource elements; generation of complex-valued time-domain OFDM signal for an antenna port; and/or the like. These functions are illustrated as examples and it is anticipated that other mechanisms may be implemented in various embodiments.

FIG. 16D illustrates another example structure for modulation and up-conversion of a baseband signal to a carrier frequency. The baseband signal may be a complex-valued OFDM baseband signal for an antenna port. Filtering may be employed prior to transmission.

A wireless device may receive from a base station one or more messages (e.g. RRC messages) comprising configuration parameters of a plurality of cells (e.g. primary cell, secondary cell). The wireless device may communicate with at least one base station (e.g. two or more base stations in dual-connectivity) via the plurality of cells. The one or more messages (e.g. as a part of the configuration parameters) may comprise parameters of physical, MAC, RLC, PCDP, SDAP, RRC layers for configuring the wireless device. For example, the configuration parameters may comprise parameters for configuring physical and MAC layer channels, bearers, etc. For example, the configuration parameters may comprise parameters indicating values of timers for physical, MAC, RLC, PCDP, SDAP, RRC layers, and/or communication channels.

A timer may begin running once it is started and continue running until it is stopped or until it expires. A timer may be started if it is not running or restarted if it is running. A timer may be associated with a value (e.g. the timer may be started or restarted from a value or may be started from zero and expire once it reaches the value). The duration of a timer may not be updated until the timer is stopped or expires (e.g., due to BWP switching). A timer may be used to measure a time period/window for a process. When the specification refers to an implementation and procedure related to one or more timers, it will be understood that there are multiple ways to implement the one or more timers. For example, it will be understood that one or more of the multiple ways to implement a timer may be used to measure a time period/window for the procedure. For example, a random access response window timer may be used for measuring a window of time for receiving a random access response. In an example, instead of starting and expiry of a random access response window timer, the time difference between two time stamps may be used. When a timer is restarted, a process for measurement of time window may be restarted. Other example implementations may be provided to restart a measurement of a time window.

A base station may transmit one or more MAC PDUs to a wireless device. In an example, a MAC PDU may be a bit string that is byte aligned (e.g., aligned to a multiple of eight bits) in length. In an example, bit strings may be represented by tables in which the most significant bit is the leftmost bit of the first line of the table, and the least significant bit is the rightmost bit on the last line of the table. More generally, the bit string may be read from left to right and then in the reading order of the lines. In an example, the bit order of a parameter field within a MAC PDU is represented with the first and most significant bit in the leftmost bit and the last and least significant bit in the rightmost bit.

In an example, a MAC SDU may be a bit string that is byte aligned (e.g., aligned to a multiple of eight bits) in length. In an example, a MAC SDU may be included in a MAC PDU from the first bit onward. A MAC CE may be a bit string that is byte aligned (e.g., aligned to a multiple of eight bits) in length. A MAC subheader may be a bit string that is byte aligned (e.g., aligned to a multiple of eight bits) in length. In an example, a MAC subheader may be placed immediately in front of a corresponding MAC SDU, MAC CE, or padding. A MAC entity may ignore a value of reserved bits in a DL MAC PDU.

In an example, a MAC PDU may comprise one or more MAC subPDUs. A MAC subPDU of the one or more MAC subPDUs may comprise: a MAC subheader only (including padding); a MAC subheader and a MAC SDU; a MAC subheader and a MAC CE; a MAC subheader and padding, or a combination thereof. The MAC SDU may be of variable size. A MAC subheader may correspond to a MAC SDU, a MAC CE, or padding.

In an example, when a MAC subheader corresponds to a MAC SDU, a variable-sized MAC CE, or padding, the MAC subheader may comprise: an R field with a one-bit length; an F field with a one-bit length; an LCID field with a multi-bit length; an L field with a multi-bit length, or a combination thereof.

FIG. 17A shows an example of a MAC subheader with an R field, an F field, an LCID field, and an L field. In the example MAC subheader of FIG. 17A, the LCID field may be six bits in length, and the L field may be eight bits in length. FIG. 17B shows example of a MAC subheader with an R field, an F field, an LCID field, and an L field. In the example MAC subheader shown in FIG. 17B, the LCID field may be six bits in length, and the L field may be sixteen bits in length. When a MAC subheader corresponds to a fixed sized MAC CE or padding, the MAC subheader may comprise: an R field with a two-bit length and an LCID field with a multi-bit length. FIG. 17C shows an example of a MAC subheader with an R field and an LCID field. In the example MAC subheader shown in FIG. 17C, the LCID field may be six bits in length, and the R field may be two bits in length.

FIG. 18A shows an example of a DL MAC PDU. Multiple MAC CEs, such as MAC CE 1 and 2, may be placed together. A MAC subPDU, comprising a MAC CE, may be placed before: a MAC subPDU comprising a MAC SDU, or a MAC subPDU comprising padding. FIG. 18B shows an example of a UL MAC PDU. Multiple MAC CEs, such as MAC CE 1 and 2, may be placed together. In an embodiment, a MAC subPDU comprising a MAC CE may be placed after all MAC subPDUs comprising a MAC SDU. In addition, the MAC subPDU may be placed before a MAC subPDU comprising padding.

In an example, a MAC entity of a base station may transmit one or more MAC CEs to a MAC entity of a wireless device. FIG. 19 shows an example of multiple LCIDs that may be associated with the one or more MAC CEs. The one or more MAC CEs comprise at least one of: a SP ZP CSI-RS Resource Set Activation/Deactivation MAC CE, a PUCCH spatial relation Activation/Deactivation MAC CE, a SP SRS Activation/Deactivation MAC CE, a SP CSI reporting on PUCCH Activation/Deactivation MAC CE, a TCI State Indication for UE-specific PDCCH MAC CE, a TCI State Indication for UE-specific PDSCH MAC CE, an Aperiodic CSI Trigger State Subselection MAC CE, a SP CSI-RS/CSI-IM Resource Set Activation/Deactivation MAC CE, a wireless device contention resolution identity MAC CE, a timing advance command MAC CE, a DRX command MAC CE, a Long DRX command MAC CE, an SCell activation/deactivation MAC CE (1 Octet), an SCell activation/deactivation MAC CE (4 Octet), and/or a duplication activation/deactivation MAC CE. In an example, a MAC CE, such as a MAC CE transmitted by a MAC entity of a base station to a MAC entity of a wireless device, may have an LCID in the MAC subheader corresponding to the MAC CE. Different MAC CE may have different LCID in the MAC subheader corresponding to the MAC CE. For example, an LCID given by 111011 in a MAC subheader may indicate that a MAC CE associated with the MAC subheader is a long DRX command MAC CE.

In an example, the MAC entity of the wireless device may transmit to the MAC entity of the base station one or more MAC CEs. FIG. 20 shows an example of the one or more MAC CEs. The one or more MAC CEs may comprise at least one of: a short buffer status report (BSR) MAC CE, a long BSR MAC CE, a C-RNTI MAC CE, a configured grant confirmation MAC CE, a single entry PHR MAC CE, a multiple entry PHR MAC CE, a short truncated BSR, and/or a long truncated BSR. In an example, a MAC CE may have an LCID in the MAC subheader corresponding to the MAC CE. Different MAC CE may have different LCID in the MAC subheader corresponding to the MAC CE. For example, an LCID given by 111011 in a MAC subheader may indicate that a MAC CE associated with the MAC subheader is a short-truncated command MAC CE.

In carrier aggregation (CA), two or more component carriers (CCs) may be aggregated. A wireless device may simultaneously receive or transmit on one or more CCs, depending on capabilities of the wireless device, using the technique of CA. In an embodiment, a wireless device may support CA for contiguous CCs and/or for non-contiguous CCs. CCs may be organized into cells. For example, CCs may be organized into one primary cell (PCell) and one or more secondary cells (SCells). When configured with CA, a wireless device may have one RRC connection with a network. During an RRC connection establishment/re-establishment/handover, a cell providing NAS mobility information may be a serving cell. During an RRC connection re-establishment/handover procedure, a cell providing a security input may be a serving cell. In an example, the serving cell may denote a PCell. In an example, a base station may transmit, to a wireless device, one or more messages comprising configuration parameters of a plurality of one or more SCells, depending on capabilities of the wireless device.

When configured with CA, a base station and/or a wireless device may employ an activation/deactivation mechanism of an SCell to improve battery or power consumption of the wireless device. When a wireless device is configured with one or more SCells, a base station may activate or deactivate at least one of the one or more SCells. Upon configuration of an SCell, the SCell may be deactivated unless an SCell state associated with the SCell is set to “activated” or “dormant”.

A wireless device may activate/deactivate an SCell in response to receiving an SCell Activation/Deactivation MAC CE. In an example, a base station may transmit, to a wireless device, one or more messages comprising an SCell timer (e.g., sCellDeactivation Timer). In an example, a wireless device may deactivate an SCell in response to an expiry of the SCell timer.

When a wireless device receives an SCell Activation/Deactivation MAC CE activating an SCell, the wireless device may activate the SCell. In response to the activating the SCell, the wireless device may perform operations comprising SRS transmissions on the SCell; CQI/PMI/RI/CRI reporting for the SCell; PDCCH monitoring on the SCell; PDCCH monitoring for the SCell; and/or PUCCH transmissions on the SCell. In response to the activating the SCell, the wireless device may start or restart a first SCell timer (e.g., sCellDeactivation Timer) associated with the SCell. The wireless device may start or restart the first SCell timer in the slot when the SCell Activation/Deactivation MAC CE activating the SCell has been received. In an example, in response to the activating the SCell, the wireless device may (re-)initialize one or more suspended configured uplink grants of a configured grant Type 1 associated with the SCell according to a stored configuration. In an example, in response to the activating the SCell, the wireless device may trigger PHR.

When a wireless device receives an SCell Activation/Deactivation MAC CE deactivating an activated SCell, the wireless device may deactivate the activated SCell. In an example, when a first SCell timer (e.g., sCellDeactivation Timer) associated with an activated SCell expires, the wireless device may deactivate the activated SCell. In response to the deactivating the activated SCell, the wireless device may stop the first SCell timer associated with the activated SCell. In an example, in response to the deactivating the activated SCell, the wireless device may clear one or more configured downlink assignments and/or one or more configured uplink grants of a configured uplink grant Type 2 associated with the activated SCell. In an example, in response to the deactivating the activated SCell, the wireless device may: suspend one or more configured uplink grants of a configured uplink grant Type 1 associated with the activated SCell; and/or flush HARQ buffers associated with the activated SCell.

When an SCell is deactivated, a wireless device may not perform operations comprising: transmitting SRS on the SCell; reporting CQI/PMI/RI/CRI for the SCell; transmitting on UL-SCH on the SCell; transmitting on RACH on the SCell; monitoring at least one first PDCCH on the SCell; monitoring at least one second PDCCH for the SCell; and/or transmitting a PUCCH on the SCell. When at least one first PDCCH on an activated SCell indicates an uplink grant or a downlink assignment, a wireless device may restart a first SCell timer (e.g., sCellDeactivationTimer) associated with the activated SCell. In an example, when at least one second PDCCH on a serving cell (e.g., a PCell or an SCell configured with PUCCH, i.e., PUCCH SCell) scheduling the activated SCell indicates an uplink grant or a downlink assignment for the activated SCell, a wireless device may restart the first SCell timer (e.g., sCellDeactivationTimer) associated with the activated SCell. In an example, when an SCell is deactivated, if there is an ongoing random access procedure on the SCell, a wireless device may abort the ongoing random access procedure on the SCell.

FIG. 21A shows an example of an SCell Activation/Deactivation MAC CE of one octet. A first MAC PDU subheader with a first LCID (e.g., ‘111010’ as shown in FIG. 19) may identify the SCell Activation/Deactivation MAC CE of one octet. The SCell Activation/Deactivation MAC CE of one octet may have a fixed size. The SCell Activation/Deactivation MAC CE of one octet may comprise a single octet. The single octet may comprise a first number of C-fields (e.g., seven) and a second number of R-fields (e.g., one).

FIG. 21B shows an example of an SCell Activation/Deactivation MAC CE of four octets. A second MAC PDU subheader with a second LCID (e.g., ‘111001’ as shown in FIG. 19) may identify the SCell Activation/Deactivation MAC CE of four octets. The SCell Activation/Deactivation MAC CE of four octets may have a fixed size. The SCell Activation/Deactivation MAC CE of four octets may comprise four octets. The four octets may comprise a third number of C-fields (e.g., 31) and a fourth number of R-fields (e.g., 1).

In FIG. 21A and/or FIG. 21B, a C_i field may indicate an activation/deactivation status of an SCell with an SCell index i if an SCell with SCell index i is configured. In an example, when the C_i field is set to one, an SCell with an SCell index i may be activated. In an example, when the C_i field is set to zero, an SCell with an SCell index i may be deactivated. In an example, if there is no SCell configured with SCell index i, the wireless device may ignore the C_i field. In FIG. 21A and FIG. 21B, an R field may indicate a reserved bit. The R field may be set to zero.

A base station may configure a wireless device with uplink (UL) bandwidth parts (BWPs) and downlink (DL) BWPs to enable bandwidth adaptation (BA) on a PCell. If carrier aggregation is configured, the base station may further configure the wireless device with at least DL BWP(s) (i.e., there may be no UL BWPs in the UL) to enable BA on an SCell. For the PCell, an initial active BWP may be a first BWP used for initial access. For the SCell, a first active BWP may be a second BWP configured for the wireless device to operate on the SCell upon the SCell being activated. In paired spectrum (e.g., FDD), a base station and/or a wireless device may independently switch a DL BWP and an UL BWP. In unpaired spectrum (e.g., TDD), a base station and/or a wireless device may simultaneously switch a DL BWP and an UL BWP.

In an example, a base station and/or a wireless device may switch a BWP between configured BWPs by means of a DCI or a BWP inactivity timer. When the BWP inactivity timer is configured for a serving cell, the base station and/or the wireless device may switch an active BWP to a default BWP in response to an expiry of the BWP inactivity timer associated with the serving cell. The default BWP may be configured by the network. In an example, for FDD systems, when configured with BA, one UL BWP for each uplink carrier and one DL BWP may be active at a time in an active serving cell. In an example, for TDD systems, one DL/UL BWP pair may be active at a time in an active serving cell. Operating on the one UL BWP and the one DL BWP (or the one DL/UL pair) may improve wireless device battery consumption. BWPs other than the one active UL BWP and the one active DL BWP that the wireless device may work on may be deactivated. On deactivated BWPs, the wireless device may: not monitor PDCCH; and/or not transmit on PUCCH, PRACH, and UL-SCH.

In an example, a serving cell may be configured with at most a first number (e.g., four) of BWPs. In an example, for an activated serving cell, there may be one active BWP at any point in time. In an example, a BWP switching for a serving cell may be used to activate an inactive BWP and deactivate an active BWP at a time. In an example, the BWP switching may be controlled by a PDCCH indicating a downlink assignment or an uplink grant. In an example, the BWP switching may be controlled by a BWP inactivity timer (e.g., bwp-InactivityTimer). In an example, the BWP switching may be controlled by a MAC entity in response to initiating a Random Access procedure. Upon addition of an SpCell or activation of an SCell, one BWP may be initially active without receiving a PDCCH indicating a downlink assignment or an uplink grant. The active BWP for a serving cell may be indicated by RRC and/or PDCCH. In an example, for unpaired spectrum, a DL BWP may be paired with a UL BWP, and BWP switching may be common for both UL and DL.

FIG. 22 shows an example of BWP switching on a cell (e.g., PCell or SCell). In an example, a wireless device may receive, from a base station, at least one RRC message comprising parameters of a cell and one or more BWPs associated with the cell. The RRC message may comprise: RRC connection reconfiguration message (e.g., RRCReconfiguration); RRC connection reestablishment message (e.g., RRCRestablishment); and/or RRC connection setup message (e.g., RRCSetup). Among the one or more BWPs, at least one BWP may be configured as the first active BWP (e.g., BWP 1), one BWP as the default BWP (e.g., BWP 0). The wireless device may receive a command (e.g., RRC message, MAC CE or DCI) to activate the cell at an n^th slot. In case the cell is a PCell, the wireless device may not receive the command activating the cell, for example, the wireless device may activate the PCell once the wireless device receives RRC message comprising configuration parameters of the PCell. The wireless device may start monitoring a PDCCH on BWP 1 in response to activating the cell.

In an example, the wireless device may start (or restart) a BWP inactivity timer (e.g., bwp-InactivityTimer) at an m^th slot in response to receiving a DCI indicating DL assignment on BWP 1. The wireless device may switch back to the default BWP (e.g., BWP 0) as an active BWP when the BWP inactivity timer expires, at s^th slot. The wireless device may deactivate the cell and/or stop the BWP inactivity timer when the sCellDeactivation Timer expires (e.g., if the cell is a SCell). In response to the cell being a PCell, the wireless device may not deactivate the cell and may not apply the sCellDeactivation Timer on the PCell.

In an example, a MAC entity may apply normal operations on an active BWP for an activated serving cell configured with a BWP comprising: transmitting on UL-SCH; transmitting on RACH; monitoring a PDCCH; transmitting PUCCH; receiving DL-SCH; and/or (re-) initializing any suspended configured uplink grants of configured grant Type 1 according to a stored configuration, if any.

In an example, on an inactive BWP for each activated serving cell configured with a BWP, a MAC entity may: not transmit on UL-SCH; not transmit on RACH; not monitor a PDCCH; not transmit PUCCH; not transmit SRS, not receive DL-SCH; clear any configured downlink assignment and configured uplink grant of configured grant Type 2; and/or suspend any configured uplink grant of configured Type 1.

In an example, if a MAC entity receives a PDCCH for a BWP switching of a serving cell while a Random Access procedure associated with this serving cell is not ongoing, a wireless device may perform the BWP switching to a BWP indicated by the PDCCH. In an example, if a bandwidth part indicator field is configured in DCI format 1_1, the bandwidth part indicator field value may indicate the active DL BWP, from the configured DL BWP set, for DL receptions. In an example, if a bandwidth part indicator field is configured in DCI format 0_1, the bandwidth part indicator field value may indicate the active UL BWP, from the configured UL BWP set, for UL transmissions.

In an example, for a primary cell, a wireless device may be provided by a higher layer parameter Default-DL-BWP a default DL BWP among the configured DL BWPs. If a wireless device is not provided a default DL BWP by the higher layer parameter Default-DL-BWP, the default DL BWP is the initial active DL BWP. In an example, a wireless device may be provided by higher layer parameter bwp-InactivityTimer, a timer value for the primary cell. If configured, the wireless device may increment the timer, if running, every interval of 1 millisecond for frequency range 1 or every 0.5 milliseconds for frequency range 2 if the wireless device may not detect a DCI format 1_1 for paired spectrum operation or if the wireless device may not detect a DCI format 1_1 or DCI format 0_1 for unpaired spectrum operation during the interval.

In an example, if a wireless device is configured for a secondary cell with higher layer parameter Default-DL-BWP indicating a default DL BWP among the configured DL BWPs and the wireless device is configured with higher layer parameter bwp-Inactivity Timer indicating a timer value, the wireless device procedures on the secondary cell may be same as on the primary cell using the timer value for the secondary cell and the default DL BWP for the secondary cell.

In an example, if a wireless device is configured by higher layer parameter Active-BWP-DL-SCell a first active DL BWP and by higher layer parameter Active-BWP-UL-SCell a first active UL BWP on a secondary cell or carrier, the wireless device may use the indicated DL BWP and the indicated UL BWP on the secondary cell as the respective first active DL BWP and first active UL BWP on the secondary cell or carrier.

In an example, a set of PDCCH candidates for a wireless device to monitor is defined in terms of PDCCH search space sets. A search space set comprises a CSS set or a USS set. A wireless device monitors PDCCH candidates in one or more of the following search spaces sets: a Type0-PDCCH CSS set configured by pdcch-ConfigSIB1 in MIB or by searchSpaceSIB1 in PDCCH-ConfigCommon or by search SpaceZero in PDCCH-ConfigCommon for a DCI format with CRC scrambled by a SI-RNTI on the primary cell of the MCG, a Type0A-PDCCH CSS set configured by search SpaceOtherSystemInformation in PDCCH-ConfigCommon for a DCI format with CRC scrambled by a SI-RNTI on the primary cell of the MCG, a Type1-PDCCH CSS set configured by ra-SearchSpace in PDCCH-ConfigCommon for a DCI format with CRC scrambled by a RA-RNTI, a MsgB-RNTI, or a TC-RNTI on the primary cell, a Type2-PDCCH CSS set configured by pagingSearch Space in PDCCH-ConfigCommon for a DCI format with CRC scrambled by a P-RNTI on the primary cell of the MCG, a Type3-PDCCH CSS set configured by SearchSpace in PDCCH-Config with searchSpace Type=common for DCI formats with CRC scrambled by INT-RNTI, SFI-RNTI, TPC-PUSCH-RNTI, TPC-PUCCH-RNTI, TPC-SRS-RNTI, CI-RNTI, or PS-RNTI and, only for the primary cell, C-RNTI, MCS-C-RNTI, or CS-RNTI(s), and a USS set configured by SearchSpace in PDCCH-Config with searchSpaceType=ue-Specific for DCI formats with CRC scrambled by C-RNTI, MCS-C-RNTI, SP-CSI-RNTI, CS-RNTI(s), SL-RNTI, SL-CS-RNTI, or SL-L-CS-RNTI.

In an example, a wireless device determines a PDCCH monitoring occasion on an active DL BWP based on one or more PDCCH configuration parameters (e.g., based on example embodiment of FIG. 27) comprising: a PDCCH monitoring periodicity, a PDCCH monitoring offset, and a PDCCH monitoring pattern within a slot. For a search space set (SS s), the wireless device determines that a PDCCH monitoring occasion(s) exists in a slot with number n_s,f^μ in a frame with number n_f if (n_f·N_slot^frame,μ+n_s,f^μ−o_s) mod k_s=0. N_slot^frame,μ is a number of slots in a frame when numerology μ is configured. o_s is a slot offset indicated in the PDCCH configuration parameters (e.g., based on example embodiment of FIG. 27). k_s is a PDCCH monitoring periodicity indicated in the PDCCH configuration parameters (e.g., based on example embodiment of FIG. 27). The wireless device monitors PDCCH candidates for the search space set for T_s consecutive slots, starting from slot n_s,f^μ and does not monitor PDCCH candidates for search space set s for the next k_s-T_s consecutive slots. In an example, a USS at CCE aggregation level L∈{1, 2, 4, 8, 16} is defined by a set of PDCCH candidates for CCE aggregation level L.

In an example, a wireless device decides, for a search space set s associated with CORESET p, CCE indexes for aggregation level L corresponding to PDCCH candidate m_s,nCI of the search space set in slot n_s,f^μ for an active DL BWP of a serving cell corresponding to carrier indicator field value n^CI as

$L·\left\{\left(Y_{p,n_{s,f}^{\mu }}+\lfloor \frac{m_{s,n_{\mathrm{CI}}}·N_{\mathrm{CCE},p}}{L·M_{s,\max }^{\left(L\right)}}\rfloor +n_{\mathrm{CI}}\right)\mathrm{mod}\lfloor N_{\mathrm{CCE},p}/L\rfloor \right\}+i,$

where, Y_p,ns,fμ=0 for any CSS; Y_p,ns,fμ=(A_p·Y_p,ns,fμ⁻¹) mod D for a USS, Y_p,−1=n_RNTI≠0, A_p=39827 for p mod 3=0, A_p=39829 for p mod 3=1, A_p=39839 for p mod 3=2, and D=65537; i=0, . . . , L−1; N_CCE,p is the number of CCEs, numbered from 0 to N_CCE,p−1, in CORESET p; n_CI is the carrier indicator field value if the wireless device is configured with a carrier indicator field by CrossCarrierSchedulingConfig for the serving cell on which PDCCH is monitored; otherwise, including for any CSS, n_CI=0; m_s,nCI=0, . . . , M_s,nCI^(L)−1, where M_s,nCI^(L) is the number of PDCCH candidates the wireless device is configured to monitor for aggregation level L of a search space set s for a serving cell corresponding to n_CI; for any CSS, M_s,max^(L)=M_s,0^(L); for a USS, M_s,max^(L) is the maximum of M_s,nCI^(L) over all configured n_CI values for a CCE aggregation level L of search space set s; and the RNTI value used for n_RNTI is the C-RNTI.

In an example, a wireless device may monitor a set of PDCCH candidates according to configuration parameters of a search space set comprising a plurality of search spaces (SSs). The wireless device may monitor a set of PDCCH candidates in one or more CORESETs for detecting one or more DCIs. A CORESET may be configured based on example embodiment of FIG. 26. Monitoring may comprise decoding one or more PDCCH candidates of the set of the PDCCH candidates according to the monitored DCI formats. Monitoring may comprise decoding a DCI content of one or more PDCCH candidates with possible (or configured) PDCCH locations, possible (or configured) PDCCH formats (e.g., number of CCEs, number of PDCCH candidates in common SSs, and/or number of PDCCH candidates in the UE-specific SSs) and possible (or configured) DCI formats. The decoding may be referred to as blind decoding. The possible DCI formats may be based on example embodiments of FIG. 23.

FIG. 23 shows examples of DCI formats which may be used by a base station transmit control information to a wireless device or used by the wireless device for PDCCH monitoring. Different DCI formats may comprise different DCI fields and/or have different DCI payload sizes. Different DCI formats may have different signaling purposes. In an example, DCI format 0_0 may be used to schedule PUSCH in one cell. DCI format 0_1 may be used to schedule one or multiple PUSCH in one cell or indicate CG-DFI (configured grant-Downlink Feedback Information) for configured grant PUSCH, etc. The DCI format(s) which the wireless device may monitor in a SS may be configured.

FIG. 24A shows an example of configuration parameters of a master information block (MIB) of a cell (e.g., PCell). In an example, a wireless device, based on receiving primary synchronization signal (PSS) and/or secondary synchronization signal (SSS), may receive a MIB via a PBCH. The configuration parameters of a MIB may comprise six bits (systemFrameNumber) of system frame number (SFN), subcarrier spacing indication (subCarrierSpacingCommon), a frequency domain offset (ssb-SubcarrierOffset) between SSB and overall resource block grid in number of subcarriers, an indication (cellBarred) indicating whether the cell is bared, a DMRS position indication (dmrs-TypeA-Position) indicating position of DMRS, parameters of CORESET and SS of a PDCCH (pdcch-ConfigSIB1) comprising a common CORESET, a common search space and necessary PDCCH parameters, etc.

In an example, a pdcch-ConfigSIB1 may comprise a first parameter (e.g., controlResourceSetZero) indicating a common ControlResourceSet (CORESET) with ID #0 (e.g., CORESET #0) of an initial BWP of the cell. controlResourceSetZero may be an integer between 0 and 15. Each integer between 0 and 15 may identify a configuration of CORESET #0.

FIG. 24B shows an example of a configuration of CORESET #0. As shown in FIG. 24B, based on a value of the integer of controlResourceSetZero, a wireless device may determine a SSB and CORESET #0 multiplexing pattern, a number of RBs for CORESET #0, a number of symbols for CORESET #0, an RB offset for CORESET #0.

In an example, a pdcch-ConfigSIB1 may comprise a second parameter (e.g., searchSpaceZero) indicating a common search space with ID #0 (e.g., SS #0) of the initial BWP of the cell. search SpaceZero may be an integer between 0 and 15. Each integer between 0 and 15 may identify a configuration of SS #0.

FIG. 24C shows an example of a configuration of SS #0. As shown in FIG. 24C, based on a value of the integer of searchSpaceZero, a wireless device may determine one or more parameters (e.g., O, M) for slot determination of PDCCH monitoring, a first symbol index for PDCCH monitoring and/or a number of search spaces per slot.

In an example, based on receiving a MIB, a wireless device may monitor PDCCH via SS #0 of CORESET #0 for receiving a DCI scheduling a system information block 1 (SIB1). A SIB1 message may be implemented based on example embodiment of FIG. 25. The wireless device may receive the DCI with CRC scrambled with a system information radio network temporary identifier (SI-RNTI) dedicated for receiving the SIB1.

FIG. 25 shows an example of RRC configuration parameters of system information block (SIB). A SIB (e.g., SIB1) may be transmitted to all wireless devices in a broadcast way. The SIB may contain information relevant when evaluating if a wireless device is allowed to access a cell, information of paging configuration and/or scheduling configuration of other system information. A SIB may contain radio resource configuration information that is common for all wireless devices and barring information applied to a unified access control. In an example, a base station may transmit to a wireless device (or a plurality of wireless devices) one or more SIB information. As shown in FIG. 25, parameters of the one or more SIB information may comprise: one or more parameters (e.g., cellSelectionInfo) for cell selection related to a serving cell, one or more configuration parameters of a serving cell (e.g., in ServingCellConfigCommonSIB IE), and one or more other parameters. The ServingCellConfigCommonSIB IE may comprise at least one of: common downlink parameters (e.g., in DownlinkConfigCommonSIB IE) of the serving cell, common uplink parameters (e.g., in UplinkConfigCommonSIB IE) of the serving cell, and other parameters.

In an example, a DownlinkConfigCommonSIB IE may comprise parameters of an initial downlink BWP (initialDownlinkBWP IE) of the serving cell (e.g., SpCell). The parameters of the initial downlink BWP may be comprised in a BWP-DownlinkCommon IE (as shown in FIG. 26). The BWP-DownlinkCommon IE may be used to configure common parameters of a downlink BWP of the serving cell. The base station may configure the locationAndBandwidth so that the initial downlink BWP contains the entire CORESET #0 of this serving cell in the frequency domain. The wireless device may apply the locationAndBandwidth upon reception of this field (e.g., to determine the frequency position of signals described in relation to this locationAndBandwidth) but it keeps CORESET #0 until after reception of RRCSetup/RRCResume/RRCReestablishment.

In an example, the DownlinkConfigCommonSIB IE may comprise parameters of a paging channel configuration. The parameters may comprise a paging cycle value (T, by defaultPagingCycle IE), a parameter (nAndPagingFrameOffset IE) indicating total number N) of paging frames (PFs) and paging frame offset (PF_offset) in a paging DRX cycle, a number (Ns) for total paging occasions (POs) per PF, a first PDCCH monitoring occasion indication parameter (firstPDCCH-MonitoringOccasionofPO IE) indicating a first PDCCH monitoring occasion for paging of each PO of a PF. The wireless device, based on parameters of a PCCH configuration, may monitor PDCCH for receiving paging message.

In an example, the parameter first-PDCCH-MonitoringOccasionOfPO may be signaled in SIB1 for paging in initial DL BWP. For paging in a DL BWP other than the initial DL BWP, the parameter first-PDCCH-MonitoringOccasionOfPO may be signaled in the corresponding BWP configuration.

FIG. 26 shows an example of RRC configuration parameters (e.g., BWP-DownlinkCommon IE) in a downlink BWP of a serving cell. A base station may transmit to a wireless device (or a plurality of wireless devices) one or more configuration parameters of a downlink BWP (e.g., initial downlink BWP) of a serving cell. As shown in FIG. 26, the one or more configuration parameters of the downlink BWP may comprise: one or more generic BWP parameters of the downlink BWP, one or more cell specific parameters for PDCCH of the downlink BWP (e.g., in pdcch-ConfigCommon IE), one or more cell specific parameters for the PDSCH of this BWP (e.g., in pdsch-ConfigCommon IE), and one or mor other parameters. A pdcch-ConfigCommon IE may comprise parameters of COESET #0 (e.g., controlResourceSetZero) which may be used in any common or UE-specific search spaces. A value of the controlResourceSetZero may be interpreted like the corresponding bits in MIB pdcch-ConfigSIB1. A pdcch-ConfigCommon IE may comprise parameters (e.g., in commonControlResourceSet) of an additional common control resource set which may be configured and used for any common or UE-specific search space. If the network configures this field, it uses a ControlResourceSetId other than 0 for this ControlResourceSet. The network configures the commonControlResourceSet in SIB1 so that it is contained in the bandwidth of CORESET #0. A pdcch-ConfigCommon IE may comprise parameters (e.g., in commonSearchSpaceList) of a list of additional common search spaces. Parameters of a search space may be implemented based on example of FIG. 27. A pdcch-ConfigCommon IE may indicate, from a list of search spaces, a search space for paging (e.g., pagingSearchSpace), a search space for random access procedure (e.g., ra-SearchSpace), a search space for SIB1 message (e.g., searchSpaceSIB1), a common search space #0 (e.g., searchSpaceZero), and one or more other search spaces.

As shown in FIG. 26, a control resource set (CORESET) may be associated with a CORESET index (e.g., ControlResourceSetId). A CORESET may be implemented based on example embodiments described above with respect to FIG. 14A and/or FIG. 14B. The CORESET index with a value of 0 may identify a common CORESET configured in MIB and in ServingCellConfigCommon (controlResourceSetZero) and may not be used in the ControlResourceSet IE. The CORESET index with other values may identify CORESETs configured by dedicated signaling or in SIB1. The controlResourceSetId is unique among the BWPs of a serving cell. A CORESET may be associated with coresetPoolIndex indicating an index of a CORESET pool for the CORESET. A CORESET may be associated with a time duration parameter (e.g., duration) indicating contiguous time duration of the CORESET in number of symbols. In an example, as shown in FIG. 26, configuration parameters of a CORESET may comprise at least one of: frequency resource indication (e.g., frequencyDomainResources), a CCE-REG mapping type indicator (e.g., cce-REG-MappingType), a plurality of TCI states, an indicator indicating whether a TCI is present in a DCI, and the like. The frequency resource indication, comprising a number of bits (e.g., 45 bits), may indicate frequency domain resources, each bit of the indication corresponding to a group of 6 RBs, with grouping starting from the first RB group in a BWP of a cell (e.g., SpCell, SCell). The first (left-most/most significant) bit may correspond to the first RB group in the BWP, and so on. A bit that is set to 1 may indicate that an RB group, corresponding to the bit, belongs to the frequency domain resource of this CORESET. Bits corresponding to a group of RBs not fully contained in the BWP within which the CORESET is configured may be set to zero.

FIG. 27 shows an example of configuration of a search space (e.g., SearchSpace IE). In an example, one or more search space configuration parameters of a search space may comprise at least one of: a search space ID (searchSpaceld), a control resource set ID (controlResourceSetId), a monitoring slot periodicity and offset parameter (monitoringSlotPeriodicityAndOffset), a search space time duration value (duration), a monitoring symbol indication (monitoringSymbols Within Slot), a number of candidates for an aggregation level (nrofCandidates), and/or a SS type indicating a common SS type or a UE-specific SS type (searchSpace Type). The monitoring slot periodicity and offset parameter may indicate slots (e.g., in a radio frame) and slot offset (e.g., related to a starting of a radio frame) for PDCCH monitoring. The monitoring symbol indication may indicate on which symbol(s) of a slot a wireless device may monitor PDCCH on the SS. The control resource set ID may identify a control resource set on which a SS may be located.

In an example, a wireless device, in RRC_IDLE or RRC_INACTIVE state, may periodically monitor paging occasions (POs) for receiving paging message for the wireless device. Before monitoring the POs, the wireless device, in RRC_IDLE or RRC_INACTIVE state, may wake up at a time before each PO for preparation and/or turn all components in preparation of data reception (warm up). The gap between the waking up and the PO may be long enough to accommodate all the processing requirements. The wireless device may perform, after the warming up, timing acquisition from SSB and coarse synchronization, frequency and time tracking, time and frequency offset compensation, and/or calibration of local oscillator. After that, the wireless device may monitor a PDCCH for a paging DCI in one or more PDCCH monitoring occasions based on configuration parameters of the PCCH configuration configured in SIB1. The configuration parameters of the PCCH configuration may be implemented based on example embodiments described above with respect to FIG. 25.

In an example, a base station may transmit one or more SSBs periodically to a wireless device, or a plurality of wireless devices. The wireless device (in RRC_idle state, RRC_inactive state, or RRC_connected state) may use the one or more SSBs for time and frequency synchronization with a cell of the base station. An SSB, comprising a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH), and a PBCH DM-RS, may be transmitted based on example embodiments described above with respect to FIG. 11A. An SSB may occupy a number (e.g., 4) of OFDM symbols as shown in FIG. 11A. The base station may transmit one or more SSBs in a SSB burst, e.g., to enable beam-sweeping for PSS/SSS and PBCH. An SSB burst comprises a set of SSBs, each SSB potentially be transmitted on a different beam. SSBs in the SSB burst may be transmitted in time-division multiplexing fashion. In an example, an SSB burst may be always confined to a 5 ms window and is either located in first half or in the second half of a 10 ms radio frame. In this specification, an SSB burst may be equivalently referred to as a transmission window (e.g., 5 ms) in which the set of SSBs are transmitted.

In an example, the base station may indicate a transmission periodicity of SSB via RRC message (e.g., ssb-PeriodicityServingCell in ServingCellConfigCommonSIB of SIB1 message, as shown in FIG. 25). A candidate value of the transmission periodicity may be in a range of {5 ms, 10 ms, 20 ms, 40 ms, 80 ms, 160 ms}. The maximum number of candidate SSBs (L_max) within an SSB burst depends upon a carrier frequency/band of the cell. In an example, L_max=4 if f_c<=3 GHZ, wherein f_c is the carrier frequency of the cell. L_max=8 if 3 GHZ<f_c<=6 GHZ. L_max=64 if f_c>=6 GHZ, etc.

In an example, a starting OFDM symbol index of a candidate SSB (occupying 4 OFDM symbols) within a SSB burst (5 ms) may depend on a subcarrier spacing (SCS) and a carrier frequency band of the cell.

FIG. 28 shows an example embodiment of starting OFDM symbol index determination.

As shown in FIG. 28, starting OFDM symbol indexes of SSBs in a SSB burst, for a cell configured with 15 kHz and carrier frequency f_c<3 GHZ (L_max=4), are 2, 8, 16, and 22. OFDM symbols in a half-frame are indexed with the first symbol of the first slot being indexed as 0. Starting OFDM symbol indexes of SSBs in a SSB burst, for a cell configured with 15 kHz and carrier frequency 3 GHZ<f_c<6 GHZ (L_max=8), are 2, 8, 16, 22, 30, 36, 44 and 50, etc. In an example, when the base station is not transmitting the SSBs with beam forming, the base station may transmit only one SSB by using the first SSB starting position.

FIG. 29 shows an example embodiment of SSB transmission of a cell by a base station. In the example of FIG. 29, a SCS of the cell is 15 kHz, and the cell is configured with 3 GHZ<f_c<=6 GHZ. Based on example embodiment of FIG. 28, maximum number of candidate SSBs in a SSB burst is 8 (L_max=8). As shown in FIG. 29, SSB #1 starts at symbol #2 of 70 symbols in 5 ms, SSB #2 starts at symbol #8, SSB #3 starts at symbol #16, SSB #4 starts at symbol #22, SSB #5 starts at symbol #30, SSB #6 starts at symbol #36, SSB #7 starts at symbol #44, and SSB #8 starts at symbol 50. The SSB burst is transmitted in the first half (not the second half as shown in FIG. 29) of a radio frame with 10 ms.

In an example, the SSB bust (also for each SSB of the SSB burst) may be transmitted in a periodicity. In the example of FIG. 29, a default periodicity of a SSB burst is 20 ms, e.g., before a wireless device receives a SIB1 message for initial access of the cell. The base station, with 20 ms transmission periodicity of SSB (or SSB burst), may transmit the SSB burst in the first 5 ms of each 20 ms. The base station does not transmit the SSB burst in the rest 15 ms of the each 20 ms.

In an example embodiment, a base station may transmit a RRC messages (e.g., SIB1) indicating cell specific configuration parameters of SSB transmission. The cell specific configuration parameters may comprise a value for a transmission periodicity (ssb-PeriodicityServingCell) of a SSB burst, locations of a number of SSBs (e.g., active SSBs), of a plurality of candidate SSBs, comprised in the SSB burst. The plurality of candidate SSBs may be implemented based on example embodiments described above with respect to FIG. 28. The cell specific configuration parameters may comprise position indication of a SSB in a SSB burst (e.g., ssb-PositionsInBurst). The position indication may comprise a first bitmap (e.g., groupPresence) and a second bitmap (e.g., inOneGroup) indicating locations of a number of SSBs comprised in a SSB burst.

FIG. 30 shows an example embodiment of SSB location indication in a SSB burst.

In the example of FIG. 30, a maximum number of candidate SSBs in an SSB burst is 64. The candidate SSBs may comprise SSBs with indexes from 0 to 63. A first bitmap (groupPresence) (configured by SIB1 message) may comprise a number of bits (e.g., 8), each bit corresponding to a respective group of SSB groups of a plurality of SSBs (which may be the maximum number of candidate SSBs) in a SSB burst. In the example of FIG. 30, a first bit (e.g., left most bit of the first bitmap) may correspond to a first SSB group comprising 1^st SSB (with SSB index 0), 2^nd SSB (with SSB index 1), . . . and 8^th SSB (with SSB index 7). A second bit (e.g., the second bit of the first bitmap) may correspond to a second SSB group comprising 9^th SSB (with SSB index 8), 10^th SSB (with SSB index 9), . . . and 16^th SSB (with SSB index 15). A last bit (e.g., right most bit of the first bitmap) may correspond to an 8^th SSB group comprising 57^th SSB (with SSB index 56), 58^th SSB (with SSB index 57, . . . and 64^th SSB (with SSB index 63), etc. In an example embodiment, a SSB may belong to at most one SSB group of the first SSB groups. A bit of the first bitmap, may indicate whether the base station transmits a SSB group, corresponding to the bit, in a SSB burst. In an example, the bit setting to a first value (e.g., 1) may indicate that the corresponding SSB group is transmitted in the SSB burst by the base station. In an example, the bit setting to a second value (e.g., 0) may indicate that the corresponding SSB group is not transmitted in the SSB burst by the base station, or vice versa.

As shown in FIG. 30, a second bitmap (inOneGroup) (configured by SIB1 message) may comprise a number of bits (e.g., 8), each bit corresponding to a respective group of SSB groups of the plurality of SSBs in a SSB burst. In the example of FIG. 30, a first bit (e.g., left most bit of the second bitmap) may correspond to a first SSB group comprising 1^st SSB (with SSB index 0), 2^nd SSB (with SSB index 8), . . . and 8^th SSB (with SSB index 56). A second bit (e.g., the second bit of the second bitmap) may correspond to a second SSB group comprising 1^st SSB (with SSB index 1), 2^nd SSB (with SSB index 9), . . . and 8^th SSB (with SSB index 57). A last bit (e.g., right most bit of the second bitmap) may correspond to an 8^th SSB group comprising 1^st SSB (with SSB index 7), 2^nd SSB (with SSB index 15, . . . and 8^th SSB (with SSB index 63), etc. In an example, a SSB may belong to at most one SSB group of the second SSB groups. A bit, of the second bitmap, may indicate whether the base station transmits a SSB group, corresponding to the bit, in a SSB burst. In an example, the bit setting to a first value (e.g., 1) may indicate that the corresponding SSB group is transmitted in the SSB burst by the base station. In an example, the bit setting to a second value (e.g., 0) may indicate that the corresponding SSB group is not transmitted in the SSB burst by the base station, or vice versa.

In the example of FIG. 30, the plurality of SSBs (e.g., with SSB index from 0 to 63) may be grouped, for the first bitmap, into first SSB groups, each SSB comprising SSBs with continuous SSB indexes. A first SSB group of the first SSB groups comprises SSBs with SSB indexes from 0 to 7, a second SSB group comprises SSB indexes from 8 to 15, etc. The plurality of SSBs may be also grouped, for the second bitmap, into second SSB groups, each SSB comprising SSBs with discontinuous SSB indexes. A first SSB group of the second SSB groups comprises SSBs with SSB indexes {0, 8, 16, . . . 56}, SSB index gap between two neighbor SSB indexes being 8. A second SSB group of the second SSB groups comprises SSBs with SSB indexes {1, 9, 17, . . . 57}, etc.

In an example embodiment, when f_c≤3 GHZ, maximum number of SSBs within SS burst equals to four and a wireless device may determine that the four leftmost bits of a bitmap (e.g., the first bitmap and/or the second bitmap) are valid. The wireless device may ignore the 4 rightmost bits of the first bitmap and/or the second bitmap.

In the example of FIG. 30, the first bitmap may be indicated, by the base station, as {1 0 1 0 0 0 0 0} and the second bitmap may be indicated as {1 1 0 0 0 0 0 0}. Based on the grouping configuration of the first SSB groups and the second SSB groups, the base station may transmit SSBs with indexes {0 1 16 17} in a SSB burst.

In an example, a base station may transmit a Master Information Block (MIB) on PBCH, to indicate configuration parameters (for CORESET #0) for a wireless device monitoring PDCCH for scheduling a SIB1 message. The base station may transmit a MIB message with a transmission periodicity of 80 millisecond (ms). The same MIB message may be repeated (according to SSB periodicity) within the 80 ms. Contents of a MIB message are same over 80 ms period. The same MIB is transmitted over all SSBs within a SS burst. In an example, PBCH may indicate that there is no associated SIB1, in which case a wireless device may be pointed to another frequency from where to search for an SSB that is associated with a SIB1 as well as a frequency range where the wireless device may assume no SSB associated with SIB1 is present. The indicated frequency range may be confined within a contiguous spectrum allocation of the same operator in which SSB is detected.

In an example, a base station may transmit a SIB1 message with a periodicity of 160 ms. The base station may transmit the same SIB1 message with variable transmission repetition periodicity within 160 ms. A default transmission repetition periodicity of SIB1 is 20 ms. The base station may determine an actual transmission repetition periodicity based on network implementation. In an example, for SSB and CORESET multiplexing pattern 1, SIB1 repetition transmission period is 20 ms. For SSB and CORESET multiplexing pattern 2/3, SIB1 transmission repetition period is the same as the SSB period. SIB1 may comprise information regarding the availability and scheduling (e.g., mapping of SIBs to SI message, periodicity, SI-window size) of other SIBs, an indication whether one or more SIBs are only provided on-demand and in which case, configuration parameters needed by a wireless device to perform an SI request.

In an example, a base station may be equipped with multiple transmission reception points (TRPs) to improve spectrum efficiency or transmission robustness. The base station may transmit DL signals/channels via intra-cell multiple TRPs (e.g., as shown in FIG. 31A) and/or via inter-cell multiple TRPs (e.g., as shown in FIG. 31B).

In an example, a base station may be equipped with more than one TRP. A first TRP may be physically located at a different place from a second TRP. The first TRP may be connected with the second TRP via a backhaul link (e.g., wired link or wireless link), the backhaul link being ideal backhaul link with zero or neglectable transmission latency, or the backhaul link being non-ideal backhaul link. A first TRP may be implemented with antenna elements, RF chain and/or baseband processor independently configured/managed from a second TRP.

FIG. 31A shows an example of a communication between a base station (equipped with multiple TRPs) and a wireless device (equipped with single panel or multiple panels) based on intra-cell TRPs. Transmission and reception with multiple TRPs may improve system throughput and/or transmission robustness for a wireless communication in a high frequency (e.g., above 6 GHZ). In an example, the multiple TRPs are associated with a same physical cell identifier (PCI). Multiple TRPs on which PDCCH/PDSCH/PUCCH/PUSCH resources of a cell are shared may be referred to as intra-cell TRPs (or intra-PCI TRPs).

In an example, a TRP of multiple TRPs of the base station may be identified by at least one of: a TRP identifier (ID), a virtual cell index, or a reference signal index (or group index). In an example, in a cell, a TRP may be identified by a control resource set (coreset) group (or pool) index (e.g., CORESETPoolIndex as shown in FIG. 26) of a coreset group from which a DCI is transmitted from the base station on a coreset. In an example, a TRP ID of a TRP may comprise a TRP index indicated in the DCI. In an example, a TRP ID of a TRP may comprise a TCI state group index of a TCI state group. A TCI state group may comprise at least one TCI state with which the wireless device receives the downlink TBs, or with which the base station transmits the downlink TBs.

In an example, a base station may transmit to a wireless device one or more RRC messages comprising configuration parameters of a plurality of CORESETs on a cell (or a BWP of the cell). Each of the plurality of CORESETs may be identified with a CORESET index and may be associated with (or configured with) a CORESET pool (or group) index. One or more CORESETs, of the plurality of CORESETs, having a same CORESET pool index may indicate that DCIs received on the one or more CORESETs are transmitted from a same TRP of a plurality of TRPs of the base station. The wireless device may determine receiving beams (or spatial domain filters) for PDCCHs/PDSCHs based on a TCI indication (e.g., DCI) and a CORESET pool index associated with a CORESET for the DCI.

In an example, a wireless device may receive multiple PDCCHs scheduling fully/partially/non-overlapped PDSCHs in time and frequency domain, when the wireless device receives one or more RRC messages (e.g., PDCCH-Config IE) comprising a first CORESET pool index (e.g., CORESETPoolIndex) value and a second COESET pool index in ControlResourceSet IE. The wireless device may determine the reception of full/partially overlapped PDSCHs in time domain only when PDCCHs that schedule two PDSCHs are associated to different ControlResourceSets having different values of CORESETPoolIndex.

In an example, a wireless device may assume (or determine) that the ControlResourceSet is assigned with CORESETPoolIndex as 0 for a ControlResourceSet without CORESETPoolIndex. When the wireless device is scheduled with full/partially/non-overlapped PDSCHs in time and frequency domain, scheduling information for receiving a PDSCH is indicated and carried only by the corresponding PDCCH. The wireless device is expected to be scheduled with the same active BWP and the same SCS. In an example, a wireless device can be scheduled with at most two codewords simultaneously when the wireless device is scheduled with full/partially overlapped PDSCHs in time and frequency domain.

In an example, when PDCCHs that schedule two PDSCHs are associated to different ControlResource Sets having different values of CORESETPoolIndex, the wireless device is allowed to the following operations: for any two HARQ process IDs in a given scheduled cell, if the wireless device is scheduled to start receiving a first PDSCH starting in symbol j by a PDCCH associated with a value of CORESETPoolIndex ending in symbol i, the wireless device can be scheduled to receive a PDSCH starting earlier than the end of the first PDSCH with a PDCCH associated with a different value of CORESETPoolIndex that ends later than symbol i; in a given scheduled cell, the wireless device can receive a first PDSCH in slot i, with the corresponding HARQ-ACK assigned to be transmitted in slot j, and a second PDSCH associated with a value of CORESETPoolIndex different from that of the first PDSCH starting later than the first PDSCH with its corresponding HARQ-ACK assigned to be transmitted in a slot before slot j.

In an example, if a wireless device configured by higher layer parameter PDCCH-Config that contains two different values of CORESETPoolIndex in ControlResourceSet, for both cases, when tci-PresentInDCI is set to ‘enabled’ and tci-PresentInDCI is not configured in RRC connected mode, if the offset between the reception of the DL DCI and the corresponding PDSCH is less than the threshold timeDurationForQCL, the wireless device may assume that the DM-RS ports of PDSCH associated with a value of CORESETPoolIndex of a serving cell are quasi co-located with the RS(s) with respect to the QCL parameter(s) used for PDCCH quasi co-location indication of the CORESET associated with a monitored search space with the lowest CORESET-ID among CORESETs, which are configured with the same value of CORESETPoolIndex as the PDCCH scheduling that PDSCH, in the latest slot in which one or more CORESETs associated with the same value of CORESETPoolIndex as the PDCCH scheduling that PDSCH within the active BWP of the serving cell are monitored by the wireless device. If the offset between the reception of the DL DCI and the corresponding PDSCH is less than the threshold timeDurationForQCL and at least one configured TCI states for the serving cell of scheduled PDSCH contains the ‘QCL-TypeD’, and at least one TCI codepoint indicates two TCI states, the wireless device may assume that the DM-RS ports of PDSCH of a serving cell are quasi co-located with the RS(s) with respect to the QCL parameter(s) associated with the TCI states corresponding to the lowest codepoint among the TCI codepoints containing two different TCI states.

FIG. 31B shows an example of a communication between a base station (equipped with multiple TRPs) and a wireless device (equipped with single panel or multiple panels) based on inter-cell TRPs (or inter-PCI TRPs). Different from FIG. 31A, the multiple TRPs are associated with different PCls. In an example, different from FIG. 31A, the multiple TRPs are associated with (or belong to) different physical cells (Cell 1 with PCI 1 and Cell 2 with PCI 2), which may be referred to as inter-cell TRPs (or inter-PCI TRPs). A cell may be a serving cell or a non-serving (neighbor) cell of the wireless device. When operating the inter-cell TRPs for a wireless device, a base station may configure Cell 2 with PCI 2 as a part of Cell 1 with PCI 1 (e.g., a second TRP with a second PCI different from a first PCI of a first TRP), in which case, the wireless device may receive 1^st SSBs from Cell 1 with PCI 1 and receive 2^nd SSBs from Cell 2 with PCI 2. The 1^st SSBs and the 2^nd SSBs may have different configuration parameters, wherein the configuration parameters may be implemented based on example embodiments described above with respect to FIG. 28, FIG. 29 and/or FIG. 30. With the inter-cell TRPs, the wireless device may receive PDCCHs/PDSCHs and/or transmit PUCCH/PUSCHs on Cell 1 with PCI1 and Cell 2 with PCI 2 with different TCI states (e.g., one being associated with one of the 1^st SSBs, another being associated with one of the 2^nd SSBs, etc.).

In an example, a serving cell may be a cell (e.g., PCell, SCell, PSCell, etc.) on which the wireless device receives SSB/CSI-RS/PDCCH/PDSCH and/or transmits PUCCH/PUSCH/SRS etc. The serving cell is identified by a serving cell index (e.g., ServCellIndex or SCellIndex configured in RRC message). For a wireless device in RRC_CONNECTED not configured with CA/DC, there is only one serving cell comprising of the primary cell. For a wireless device in RRC_CONNECTED configured with CA/DC the term ‘serving cells’ is used to denote the set of cells comprising of the Special Cell(s) and all secondary cells. For a wireless device configured with CA, a cell providing additional radio resources on top of Special Cell is referred to as a secondary cell.

In an example, a non-serving (or neighbor) cell may be a cell on which the wireless device does not receive MIBs/SIBs/PDCCH/PDSCH and/or does not transmit PUCCH/PUSCH/SRS etc. The non-serving cell has a physical cell identifier (PCI) different from a PCI of a serving cell. The non-serving cell may not be identified by (or associated with) a serving cell index (e.g., ServCellIndex or SCellIndex). The wireless device may rely on a SSB of a non-serving cell for Tx/Rx beam (or spatial domain filter) determination (for PDCCH/PDSCH/PUCCH/PUSCH/CSI-RS/SRS for a serving cell, etc.) if a TCI state of the serving cell is associated with (e.g., in TCI-state IE of TS 38.331) a SSB of the non-serving cell. The base station does not transmit RRC messages configuring resources of PDCCH/PDSCH/PUCCH/PUSCH/SRS of a non-serving cell for the wireless device.

In the example of FIG. 31B, for a specific wireless device, Cell 1 is a serving cell and is associated with a first TRP (TRP 1). Cell 2 is a non-serving (or neighbor) cell and is associated with a second TRP. A base station may transmit to a wireless device one or more RRC messages comprising configuration parameters of Cell 1. The configuration parameters of Cell 1 may indicate a plurality of additional PCI configurations (e.g., SSB-MTC-AdditionalPCI IE) for a plurality of (non-serving or neighbor) cells for cell 1, each additional PCI configuration corresponding to a (non-serving or neighbor) cell having a PCI different from the PCI value of the serving cell, and comprising: an additional PCI index (AdditionalPCIIndex) identifying the additional PCI configuration, a PCI of the non-serving cell, a SSB periodicity indication, position indications of (candidate) SSBs in a SSB burst, a transmission power indication of SSBs, etc. The configuration parameter of Cell 1 may further indicate a plurality of TCI states. Each TCI state of the plurality of TCI states may be associated with one or more TCI parameters comprising a TCI state identifier identifying the TCI state, one or more QCL information parameters comprising a SSB index identifying the SSB and a QCL type indicator indicating a QCL type of a plurality of QCL types, e.g., if the SSB is transmitted via Cell 1 (or in another serving cell). If a SSB of a TCI state is transmitted via a non-serving (neighbor) cell, the TCI state may be further associated with an additional PCI index (AdditionalPCIIndex) indicating a (non-serving or neighbor) cell configured in the SSB-MTC-AdditionalPCI IE. Similar to intra-cell multiple TRPs, the wireless device may receive downlink signals and/or transmit uplink signals based on a TCI state (activated/indicated) associated with a TRP. The difference between intra-cell multiple TRPs and inter-cell multiple TRPs is that a reference RS of a TCI state for a serving cell may come from (or be transmitted via) a (non-serving or neighbor) cell for the latter cases. A SSB may be implemented based on example embodiments described above with respect to FIG. 28, FIG. 29 and/or FIG. 30.

In the example of FIG. 31B, Cell 1 is a serving cell for a wireless device. Cell 2 is a (non-serving or neighbor) cell associated with Cell 1 for the wireless device. Cell 2 may be a serving cell for a second wireless device. Cell 1 may be a (non-serving or neighbor) cell for the second wireless device. Different wireless devices may have different serving cells and non-serving/neighbor cells.

In an example, the base station may use both TRPs for transmissions via Cell 1 to a wireless device. In an example, the base station may indicate (by DCI/MAC CE) a first TCI state associated with an SSB/CSI-RS transmitted via Cell 1 (or another serving cell) for a first transmission (via PDCCH/PDSCH/PUSCH/PUCCH/SRS resources of Cell 1) to the wireless device. In addition, the base station may indicate (by the same DCI/MAC CE or another DCI/MAC CE) a second TCI state associated with a second SSB transmitted via Cell 2 (which is the non-serving/neighbor) cell indicated by AdditionalPCIIndex in TCI configuration parameters) for a second transmission (via PDCCH/PDSCH/PUSCH/PUCCH/SRS resources of Cell 1) to the wireless device. The second SSB transmitted via Cell 2 is different from the first SSB transmitted via Cell 1. Using two TCI states from two TRPs (one is from a serving cell and another is from a non-serving/neighbor cell) may avoid executing time-consuming handover (HO) between Cell 1 to Cell 2 and improve coverage if the wireless device is moving at the edge of Cell 1 and Cell 2.

In the examples of FIG. 31A and FIG. 31B, a wireless device may be provided with two TCI states, each TCI state corresponding to a TRP of multiple TRPs. A TCI state may be referred to as a channel-specific TCI state, when the TCI state is used for a specific channel (e.g., PDSCH/PDCCH/PUCCH/PUSCH), where different channels may be associated with different channel-specific TCI states. A TCI state may be referred to as a unified TCI state, when the TCI state is used for multiple channels (e.g., PDSCH/PDCCH/PUCCH/PUSCH), where different channels may be associated with the same unified TCI state. The base station may transmit RRC messages indicating whether a TCI state is a unified TCI state for the wireless device.

Based on FIG. 31A and FIG. 31B, a base station may perform data/signaling transmissions based on intra-cell multiple TRPs (e.g., which may be referred to as Intra-cell M-TRP or Intra-PCI M-TRP) for a wireless device, e.g., when the wireless device is close to the center of a cell, has more data to deliver and/or requires high reliability (e.g., for URLLC service). The base station may perform data/signaling transmissions based on inter-cell multiple TRPs (e.g., which may be referred to as Inter-cell M-TRP or Inter-PCI M-TRP) for a wireless device, e.g., when the wireless device is at the edge of a cell and is (moving or located) in the coverage of another cell (which may be or may not be a serving cell of the wireless device).

In exiting technologies, a base station may enable a power saving operation for a wireless device due to limited battery capacity of the wireless device, e.g., based on BWP management, SCell dormancy mechanism, wake-up/go-to-sleep indication, SSSG switching on an active BWP, and/or PDCCH skipping.

However, a base station, when indicating a power saving operation for a wireless device, may not be able to save energy from the viewpoint of the base station, e.g., when the base station is required to transmit some always-on downlink signals periodically (e.g., SSB, MIB, SIB1, SIB2, periodic CSI-RS, etc.) in some time period even when there is no active wireless device in transmitting to/receiving from the base station. The base station may be required to transmit some always-on downlink signals periodically (e.g., SSB, MIB, SIB1, SIB2, periodic CSI-RS, etc.) when the base station transitions a cell into a dormant state by switching an active BWP to a dormant BWP of the cell.

In an example, if a base station needs to reduce periodicity of the always-on downlink signal transmission for network energy saving, the base station may transmit a RRC message (e.g., SIB1) indicating a longer periodicity for the always-on downlink signal transmission.

In an example, a base station, before determining to power off (e.g., both RF modules and base band units (BBUs) for network energy saving, may transmit RRC reconfiguration messages to each wireless device in a source cell to indicate a handover to a neighbor cell. A handover (HO) procedure may be implemented based on example embodiments of FIG. 32.

FIG. 32 shows an example of executing HO procedure from a source gNB to a target gNB for a wireless device.

In an example, for network-controlled mobility in RRC_CONNECTED, the PCell may be changed using an RRC connection reconfiguration message (e.g., RRCReconfiguration) including reconfigurationWith Sync (in NR specifications) or mobilityControlInfo in LTE specifications (handover). The SCell(s) may be changed using the RRC connection reconfiguration message either with or without the reconfigurationWithSync or mobilityControlInfo. The network may trigger the HO procedure e.g., based on radio conditions, load, QOS, UE category, and/or the like. The RRC connection reconfiguration message may be implemented based on example embodiments which will be described later in FIG. 33 and FIG. 34.

As shown in FIG. 32, the network may configure the wireless device to perform measurement reporting (possibly including the configuration of measurement gaps). The measurement reporting is a layer 3 reporting, different from layer 1 CSI reporting. The wireless device may transmit one or more measurement reports to the source gNB (or source PCell). In an example, the network may initiate HO blindly, for example without having received measurement reports from the wireless device. Before sending the HO message to the wireless device, the source gNB may prepare one or more target cells. The source gNB may select a candidate target PCell.

As shown in FIG. 32, based on the one or more measurement reports from the wireless device, the source gNB may provide the target gNB with a list of best cells on each frequency for which measurement information is available, for example, in order of decreasing RSRP values. The source gNB may also include available measurement information for the cells provided in the list. The target gNB may decide which cells are configured for use after HO, which may include cells other than the ones indicated by the source gNB. In an example, as shown in FIG. 32, the source gNB may transmit a HO request to the target gNB. The target gNB may response with a HO message. In an example, in the HO message, the target gNB may indicate access stratum configuration to be used in the target cell(s) for the wireless device.

In an example, the source gNB may transparently (for example, does not alter values/content) forward the HO message/information received from the target gNB to the wireless device. In the HO message, RACH resource configuration may be configured for the wireless device to access a cell in the target gNB. When appropriate, the source gNB may initiate data forwarding for (a subset of) the dedicated radio bearers.

As shown in FIG. 32, after receiving the HO message, the wireless device may start a HO timer (e.g., T304) with an initial timer value. The HO timer may be configured in the HO message. Based on the HO message, the wireless device may apply the RRC parameters of the target PCell and/or a cell group (MCG/SCG) associated with the target PCell of the target gNB and perform downlink synchronization to the target gNB. After or in response to performing downlink synchronization (e.g., searching a suitable/detectable SSB from candidate SSBs configured on the target gNB, based on examples of FIG. 29 and/or FIG. 30) to the target gNB, the wireless device may initiate a random access (e.g., contention-free, or contention-based, based on examples of FIG. 13A, FIG. 13B and/or FIG. 13C) procedure attempting to access the target gNB at the available RACH occasion according to a RACH resource selection, where the available RACH occasion may be configured in the RACH resource configuration (e.g., based on example embodiments of FIG. 34 which will be described later). When allocating a dedicated preamble for the random access in the target gNB, RAN may ensure the preamble is available from the first RACH occasion the wireless device may use.

In an example, the wireless device may activate the uplink BWP configured with firstActiveUplinkBWP-id and the downlink BWP configured with firstActiveDownlinkBWP-id on the target PCell upon performing HO to the target PCell.

In an example, the wireless device, after applying the RRC parameters of a target PCell and/or completing the downlink synchronization with the target PCell, may perform UL synchronization by conducting RACH procedure, e.g., based on example embodiments described above with respect to FIG. 13A, FIG. 13B and/or FIG. 13C. The performing UL synchronization may comprise transmitting a preamble via an active uplink BWP (e.g., a BWP configured as firstActiveUplinkBWP-id as shown in FIG. 33) of uplink BWPs of the target PCell, monitoring PDCCH on an active downlink BWP (e.g., a BWP configured as firstActiveDownlinkBWP-id as shown in FIG. 33) for receiving a RAR comprising a TA which is used for PUSCH/PUCCH transmission via the target PCell, receiving the RAR and/or obtaining the TA. After completing the UL synchronization, the wireless device obtains the TA to be used for PUSCH/PUCCH transmission via the target PCell. The wireless device, by using the TA to adjust uplink transmission timing, transmits PUSCH/PUCCH via the target PCell. The adjusting uplink transmission timing may comprise advancing or delay the transmissions by an amount indicated by a value of the TA, e.g., to ensure the uplink signals received at the target PCell are aligned (in time domain) with uplink signals transmitted from other wireless devices.

In an example, the wireless device may release RRC configuration parameters of the source PCell and an MCG/SCG associated with the source PCell.

In this specification, a HO triggered by receiving a RRC reconfiguration message (e.g., RRCReconfiguration) comprising the HO command/message (e.g., by including reconfiguration WithSync (in NR specifications) or mobilityControlInfo in LTE specifications (handover) is referred to as a normal HO, an unconditional HO, which is contrast with a conditional HO (CHO) which will be described later in FIG. 35.

In an example, as shown in FIG. 32, the wireless device may transmit a preamble to the target gNB via a RACH resource. The RACH resource may be selected from a plurality of RACH resources (e.g., configured in rach-ConfigDedicated IE as shown in FIG. 33 and FIG. 34) based on SSBs/CSI-RSs measurements of the target gNB. The wireless device may select a (best) SSB/CSI-RS of the configured SSBs/CSI-RSs of the target gNB. The wireless device may select an SSB/CSI-RS, from the configured SSBs/CSI-RSs of the target gNB, with a RSRP value greater than a RSRP threshold configured for the RA procedure. The wireless device then determines a RACH occasion (e.g., time domain resources, etc.) associated with the selected SSB/CSI-RS and determines the preamble associated with the selected SSB/CSI-RS.

In an example, the target gNB may receive the preamble transmitted from the wireless device. The target gNB may transmit a random access response (RAR) to the wireless device, where the RAR comprises the preamble transmitted by the wireless device. The RAR may further comprise a TAC to be used for uplink transmission via the target PCell. In response to receiving the RAR comprising the preamble, the wireless device may complete the random access procedure. In response to completing the random access procedure, the wireless device may stop the HO timer (T304). The wireless device may transmit an RRC reconfiguration complete message to the target gNB, after completing the random access procedure, or before completing the random access procedure. The wireless device, after completing the random access procedure towards the target gNB, may apply first parts of CQI reporting configuration, SR configuration and SRS configuration that do not require the wireless device to know a system frame number (SFN) of the target gNB. The wireless device, after completing the random access procedure towards the target PCell, may apply second parts of measurement and radio resource configuration that require the wireless device to know the SFN of the target gNB (e.g., measurement gaps, periodic CQI reporting, SR configuration, SRS configuration), upon acquiring the SFN of the target gNB.

In an example, based on HO procedure (e.g., as shown in FIG. 32), for network energy saving purpose, a base station may instruct each wireless device in a source cell to perform a 4-step or 2-step RACH-based (contention free) HO to a neighbor cell. After the wireless devices complete the HO procedure to neighbor cells, the base station may turn off (RF parts and BBUs, etc.) for energy saving.

FIG. 33 shows an example embodiment of RRC message for HO. In the example of FIG. 33, a base station may transmit, and/or a wireless device may receive, an RRC reconfiguration message (e.g., RRCReconfiguration-IEs) indicating an RRC connection modification. It may convey information for measurement configuration, mobility control, radio resource configuration (including RBs, MAC main configuration and physical channel configuration) and AS security configuration. The RRC reconfiguration message may comprise a configuration of a master cell group (masterCellGroup). The master cell group may be associated with a SpCell (SpCellConfig). When the SpCellConfig comprises a reconfiguration with Sync (reconfigurationWithSync), the wireless device determines that the SpCell is a target PCell for the HO. The reconfiguration with sync (reconfigurationWithSync) may comprise cell common parameters (spCellConfigCommon) of the target PCell, a RNTI (newUE-Identity) identifying the wireless device in the target PCell, a value of T304, a dedicated RACH resource (rach-ConfigDedicated), etc. In an example, a dedicated RACH resource may comprise one or more RACH occasions, one or more SSBs, one or more CSI-RSs, one or more RA preamble indexes, etc.

FIG. 34 shows an example embodiment of RRC messages for RACH resource configuration for HO procedure based on example embodiments described above with respect to FIG. 33. As shown in FIG. 33, the reconfiguration WithSync IE comprises a dedicated RACH resource indicated by a rach-ConfigDedicated IE.

As shown in FIG. 34, a rach-ConfigDedicated IE comprises a contention free RA resource indicated by a cfra IE. The cfra IE comprises a plurality of occasions indicated by a rach-ConfigGeneric IE, a ssb-perRACH-Occasion IE, a plurality of resources associated with SSB (indicated by a ssb IE) or CSI-RS (indicated by a csirs IE). The ssb-perRACH-Occasion IE indicates a number of SSBs per RACH occasion. The rach-ConfigGeneric IE indicates configuration of CFRA occasions. The wireless device ignores preambleReceivedTargetPower, preamble TransMax, powerRampingStep, ra-ResponseWindow signaled within this field and use the corresponding values provided in RACH-ConfigCommon.

As shown in FIG. 34, when the plurality of resources for the CFRA configured in the reconfiguration WithSync IE are associated with SSBs, the resources (resources (E) comprise the ssb IE. The ssb IE comprises a list of CFRA SSB resources (ssb-ResourceList) and an indication of PRACH occasion mask index (ra-ssb-OccasionMaskIndex). Each of the list of CFRA SSB resources comprises an SSB index, a RA preamble index and etc. The ra-ssb-OccasionMaskIndex indicates a PRACH mask index for RA resource selection. The mask is valid for all SSB resources signaled in ssb-ResourceList.

A shown in FIG. 34, when the plurality of resources for the CFRA configured in the reconfigurationWithSync IE are associated with CSI-RSs, the resources (resources (E) comprise the csirs IE. The csirs/E comprises a list of CFRA CSI-RS resources (csirs-ResourceList) and a RSRP threshold (rsrp-ThresholdCSI-RS). Each of the list of CFRA CSI-RS resources comprises a CSI-RS index, a list of RA occasions (ra-OccasionList), a RA preamble index etc.

In an example, executing the HO triggered by receiving a RRC reconfiguration message comprising a reconfigurationWithSync IE may introduce HO latency (e.g., too-late HO), e.g., when a wireless device is moving in a network deployed with multiple small cells (e.g., with hundreds of meters of cell coverage of a cell). An improved HO mechanism, based on measurement event triggering, is proposed to reduce the HO latency as shown in FIG. 35.

FIG. 35 shows an example embodiment of conditional handover (CHO) procedure. In an example, as shown in FIG. 35, the network (e.g., a base station, a source gNB) may configure the wireless device to perform measurement reporting (possibly including the configuration of measurement gaps) for a plurality of neighbor cells (e.g., cells from a candidate target gNB 1, a candidate target gNB 2, etc.). The measurement reporting is a layer 3 reporting, different from layer 1 CSI reporting. The wireless device may transmit one or more measurement reports to the source gNB (or source PCell).

As shown in FIG. 35, based on the one or more measurement reports from the wireless device, the source gNB may provide the target gNB with a list of best cells on each frequency for which measurement information is available, for example, in order of decreasing RSRP. The source gNB may also include available measurement information for the cells provided in the list. The target gNB may decide which cells are configured for use after the CHO, which may include cells other than the ones indicated by the source gNB. In an example, as shown in FIG. 35, the source gNB may transmit a HO request to the target gNB. The target gNB may response with a HO message. In an example, in the HO message, the target gNB may indicate access stratum configuration (e.g., RRC configurations of the target cells) to be used in the target cell(s) for the wireless device.

In an example, the source gNB may transparently (for example, does not alter values/content) forward the handover (e.g., contained in RRC reconfiguration messages of the target gNB) message/information received from the target gNB to the wireless device.

In an example, the source gNB may configure a CHO procedure different from a normal HO procedure (e.g., as shown in FIG. 32, FIG. 33 and/or FIG. 34), by comprising a conditional reconfiguration message (e.g., conditionalReconfiguration IE in RRC reconfiguration message, which will be described later in FIG. 36). The conditional reconfiguration message may comprise a list of candidate target PCells, each candidate target PCell being associated with dedicated RACH resources for the RA procedure in case a CHO is executed to the candidate target PCell. A CHO execution condition (or RRC reconfiguration condition) is also configured for each of the candidate target PCells, etc. In an example, a CHO execution condition may comprise a measurement event A3 where a candidate target PCell becomes amount of offset better than the current PCell (e.g., the PCell of the source gNB), a measurement event A4 where a candidate target PCell becomes better than absolute threshold configured in the RRC reconfiguration message, a measurement event A5 where the current PCell becomes worse than a first absolute threshold and a candidate target PCell becomes better than a second absolute threshold, etc.

In the example of FIG. 35, the wireless device, according to the received RRC reconfiguration messages comprising parameters of a CHO procedure, may evaluate the (RRC) reconfiguration conditions for the list of candidate target PCells and/or the current/source PCell. The wireless device may measure RSRP/RSRQ of SSBs/CSI-RSs of each candidate target PCell of the list of candidate target PCells. Different from the normal HO procedure described in FIG. 32, the wireless device does not execute the HO to the target PCell in response to receiving the RRC reconfiguration messages comprising the parameters of the CHO procedure. The wireless device may execute the HO to a target PCell for the CHO only when the (RRC) reconfiguration condition(s) of the target PCell are met (or satisfied). Otherwise, the wireless device may keep evaluating the reconfiguration conditions for the list of the candidate target PCells, e.g., until an expiry of a HO timer, or receiving a RRC reconfiguration indicating an abort of the CHO procedure.

In the example of FIG. 35, in response to a reconfiguration condition of a first candidate target PCell (e.g., PCell 1) being met or satisfied, the wireless device may execute the CHO procedure towards the first candidate target PCell. The wireless device may select one of multiple candidate target PCells by its implementation when the multiple candidate target PCells have reconfiguration conditions satisfied or met.

In an example, executing the CHO procedure towards the first candidate target PCell is same as or similar to executing the HO procedure as shown in FIG. 32. By executing the CHO procedure, the wireless device may release RRC configuration parameters of the source PCell and the MCG associated with the source PCell, apply the RRC configuration parameters of the PCell 1, reset MAC, perform cell group configuration for the received MCG comprised in the RRC reconfiguration message of the PCell 1, and/or perform RA procedure to the PCell 1, etc.

In an example, the MCG of the RRC reconfiguration message of the PCell 1 may be associated with a SpCell (SpCellConfig) on the target gNB 1. When the sPCellConfig comprises a reconfiguration with Sync (reconfiguration WithSync), the wireless device determines that the SpCell is a target PCell (PCell 1) for the HO. The reconfiguration with sync (reconfigurationWithSync) may comprise cell common parameters (spCellConfigCommon) of the target PCell, a RNTI (newUE-Identity) identifying the wireless device in the target PCell, a value of T304, a dedicated RACH resource (rach-ConfigDedicated), etc. In an example, a dedicated RACH resource may comprise one or more RACH occasions, one or more SSBs, one or more CSI-RSs, one or more RA preamble indexes, etc. In an example, the wireless device may perform cell group configuration for the received master cell group comprised in the RRC reconfiguration message of the PCell 1 on the target gNB 1 according to the example embodiments described above with respect to FIG. 32.

FIG. 36 shows an example of RRC message for CHO. In the example of FIG. 36, a base station may transmit, and/or a wireless device may receive, an RRC reconfiguration message (e.g., RRCReconfiguration-V1610-IEs) indicating an RRC connection modification. The RRC reconfiguration message may be comprised in a (parent) RRC reconfiguration message (e.g., RRCReconfiguration-IEs) as shown in FIG. 33, where the (parent) RRC reconfiguration message may comprise (L3 beam/cell) measurement configuration (e.g., measConfig IE).

In the example of FIG. 36, the RRC reconfiguration message (e.g., RRCReconfiguration-V1610-IEs) may comprise a conditional reconfiguration IE (conditionalReconfiguration IE). The conditional reconfiguration IE may comprise a list of conditional reconfigurations (condReconfigToAddModList). Each conditional reconfiguration corresponds to a respective candidate target cell (PCell) of a list of candidate target cells. For each conditional reconfiguration of the list of conditional reconfigurations, the base station may indicate one or more measurement events (condExecutionCond) for triggering the CHO on the candidate target PCell, a RRC reconfiguration message (condRRCReconfig) of a candidate target cell (PCell) which is received by the source gNB from the target gNB via X2/Xn interface. The RRC reconfiguration message of the candidate target cell may be implemented based on example embodiments described above with respect to FIG. 33 and/or FIG. 34. In an example, the RRC reconfiguration message may comprise a configuration of a master cell group (masterCellGroup) for the target gNB. The master cell group may be associated with a SpCell (SpCellConfig). When the sPCellConfig comprises a reconfiguration with Sync (reconfiguration WithSync), the SpCell is a target PCell for executing the CHO. The reconfiguration with sync (reconfiguration WithSync) may comprise cell common parameters (spCellConfigCommon) of the target PCell, a RNTI (newUE-Identity) identifying the wireless device in the target PCell, a value of T304, a dedicated RACH resource (rach-ConfigDedicated), etc. In an example, a dedicated RACH resource may comprise one or more RACH occasions, one or more SSBs, one or more CSI-RSs, one or more RA preamble indexes, etc.

In the example of FIG. 36, a measurement event (condExecutionCond) for triggering the CHO on the candidate target PCell is an execution condition that needs to be fulfilled (at the wireless device) in order to trigger the execution of a conditional reconfiguration for CHO. The indication of the measurement event may point to a measurement ID (MeasId) which identifies a measurement configuration of a plurality of measurement configurations (e.g., comprised in measConfig IE) configured by the source gNB. The measurement configuration may be associated with a measurement event (or a conditional event) of a plurality of measurements. A conditional event may comprise a conditional event A3, conditional event A4, and/or conditional event A5, etc. A conditional event A3 is that a candidate target PCell becomes amount of offset better than the current PCell (e.g., the PCell of the source gNB). A conditional event A4 is that a candidate target PCell becomes better than an absolute threshold configured in the RRC reconfiguration message. A conditional event A5 is that the current PCell becomes worse than a first absolute threshold and a candidate target PCell becomes better than a second absolute threshold, etc.

In an example, executing CHO by the wireless device's decision based on evaluating reconfiguration conditions (long-term and/or layer 3 beam/cell measurements against one or more configured thresholds) on a plurality of candidate target cells may cause load unbalanced on cells, and/or lead to CHO failure in case that the target cell changes its configuration (e.g., for network energy saving) during the CHO condition evaluation, etc. An improved handover based on layer 1/2 signaling triggering is proposed in FIG. 37. In an example, a layer 1 signaling may comprise a DCI transmitted via a PDCCH. A layer 2 signaling may comprise a MAC CE scheduled by a DCI. Layer 1/2 signaling is different from Layer 3 signaling, for HO/CHO, which comprises RRC reconfiguration message.

FIG. 37 shows an example embodiment of layer 1/2 triggered HO procedure. In an example, as shown in FIG. 37, the network (e.g., a base station, a source gNB) may configure the wireless device to perform measurement reporting (possibly including the configuration of measurement gaps) for a plurality of neighbor cells (e.g., cells from a candidate target gNB 1, a candidate target gNB 2, etc.). The measurement reporting is a layer 3 reporting, different from layer 1 CSI reporting. The wireless device may transmit one or more measurement reports to the source gNB (or source PCell, cell 0 in FIG. 37).

As shown in FIG. 37, based on the one or more measurement reports from the wireless device, the source gNB may provide the target gNB with a list of best cells on each frequency for which measurement information is available, for example, in order of decreasing RSRP. The source gNB may also include available measurement information for the cells provided in the list. The target gNB may decide which cells are configured for use (as a target PCell, and/or one or more SCells) after HO, which may include cells other than the ones indicated by the source gNB. In an example, as shown in FIG. 37, the source gNB may transmit a HO request to the target gNB. The target gNB may response with a HO message. In an example, in the HO message, the target gNB may indicate access stratum configuration (e.g., RRC configurations of the target cells) to be used in the target cell(s) for the wireless device.

In an example, the source gNB may transparently (for example, does not alter values/content) forward the HO (e.g., contained in RRC reconfiguration messages of the target gNB, cell group configuration IE of the target gNB, and/or SpCell configuration IE of a target PCell/SCells of the target gNB) message/information received from the target gNB to the wireless device.

In an example, the source gNB may configure a Layer 1/2 signaling based HO (PCell switching/changing, mobility, etc.) procedure different from a normal HO procedure (e.g., as shown in FIG. 32, FIG. 33 and/or FIG. 34) and/or a CHO procedure (e.g., as shown in FIG. 35 and/or FIG. 36), by comprising a Layer 1/2 candidate PCell configuration message (e.g., a newly defined candidates-L1L2-Config IE) in RRC reconfiguration message of the source gNB. The Layer 1/2 candidate PCell configuration message may comprise a list of candidate target PCells, each candidate target PCell being associated with dedicated RACH resources for the RA procedure in case a Layer 1/2 signaling based HO is trigged by a Layer 1/2 signaling and executed to the candidate target PCell, etc. There may be multiple options for parameter configurations of a candidate target PCell.

In an example, as a first option for the parameter configuration, for each candidate target PCell, the RRC reconfiguration message of the source gNB may comprise a (capsuled) RRC reconfiguration message (e.g., RRCReconfiguration), of a candidate target gNB, received by the source gNB from a candidate target gNB via X2/Xn interface. The (capsuled) RRC reconfiguration message, of the candidate target gNB, may reuse the same signaling structure of the RRC reconfiguration message of the source gNB, as shown in FIG. 33 and/or FIG. 34.

In an example, as a second option for the parameter configuration, for each candidate target PCell, the RRC reconfiguration message of the source gNB may comprise a (capsuled) cell group configuration message (e.g., CellGroupConfig), of a candidate target gNB, received by the source gNB from a candidate target gNB via X2/Xn interface. The (capsuled) cell group configuration message, of the candidate target gNB, may reuse the same signaling structure of the cell group configuration message of the source gNB, as shown in FIG. 33 and/or FIG. 34. The second option may reduce signaling overhead of the parameter configuration of a candidate target PCell compared with the first option.

In an example, as a third option for the parameter configuration, for each candidate target PCell, the RRC reconfiguration message of the source gNB may comprise a (capsuled) SpCell configuration message (e.g., SpCellConfig), of a candidate target gNB, received by the source gNB from a candidate target gNB via X2/Xn interface. The (capsuled) SpCell configuration message, of the candidate target gNB, may reuse the same signaling structure of the SpCell configuration message of the source gNB, as shown in FIG. 33 and/or FIG. 34. The third option may reduce signaling overhead of the parameter configuration of a candidate target PCell compared with the second option.

In an example, for each candidate target PCell, the source gNB may indicate cell common and/or UE specific parameters (e.g., SSBs/CSI-RSs, BWPs, RACH resources, PDCCH/PDSCH/PUCCH/PUSCH resources etc.).

In the example of FIG. 37, the wireless device, according to the received RRC reconfiguration messages comprising parameters of a Layer 1/2 signaling based HO procedure, may perform Layer 1/2 measurement report (CSI/beam) for the list of candidate target PCells and/or the current PCell. The layer 1/2 measurement report may comprise layer 1 RSRP, layer 1 RSRQ, PMI, RI, layer 1 SINR, CQI, etc.

In an example, the layer 1/2 measurement report may be transmitted with a periodicity configured by the source gNB.

In an example, the layer 1/2 measurement report may be triggered when the measurement of the CSI/beam of a candidate target PCell is greater than a threshold, or (amount of offset) greater than the current PCell, etc.

In the example of FIG. 37, the base station may perform an inter-cell beam management (ICBM) procedure before transmitting a Layer 1/2 signaling triggering the HO procedure comprising switching PCell from the source gNB to a target gNB. The ICBM procedure may allow the base station and the wireless device to use resources (time/frequency/spatial) of the target gNB (or a PCell/SCell of the target gNB) without executing HO procedure to the target gNB, therefore reducing frequently executing the HO procedure. The ICBM procedure may allow the base station and the wireless device to synchronize time/frequency/beam to a target PCell of the target gNB before executing the HO, which may reduce HO latency. The ICBM may be implemented based on example embodiments of FIG. 38 which will be described later.

In the example of FIG. 37, in response to the ICBM procedure being configured, the source gNB may transmit to the wireless device a first DCI/MAC CE configuring/indicating a first candidate target cell (e.g., Cell 1) of the candidate target cells (PCells/SCells) as a neighbor or non-serving cell, in addition to the current PCell (e.g., Cell 0), for the wireless device. The base station may select the first candidate target cell from the candidate target cells, based on layer 1/2 measurement report from the wireless device.

In an example, the first DCI/MAC CE (e.g., activating TCI states) may indicate that a reference RS (e.g., SSB/CSI-RS) associated with a first TCI state is from the first candidate target cell (Cell 1) (e.g., by associating the reference RS with an additional PCI, of Cell1, different from a PCI of the Cell 0), in addition to a reference RS associated with a second TCI state being from the current PCell (Cell 0). Association between a reference signal and a TCI state may be implemented based on example embodiments described above with respect to FIG. 31B. Activating, by a DCI/MAC CE, a TCI state with a RS of a neighbor (non-serving) cell as a reference RS, may allow the base station to use a beam of the neighbor cell to transmit downlink signals/channels or to receive uplink signals/channels, and/or use a beam of the current cell for the transmissions/receptions, without performing HO to the neighbor cell for the transmissions/receptions.

In the example of FIG. 37, the wireless device, in response to receiving the first DCI/MAC CE, may apply the first TCI state and the second TCI state for downlink reception and/or uplink transmission.

In an example, applying the first TCI state and the second TCI state for downlink reception may comprise: receiving (from Cell 1) PDCCH/PDSCH/CSI-RS with a reception beam/filter same as that for receiving the reference signal, transmitted from Cell 1, according to (or associated with) the first TCI state, and receiving (from cell 0) PDCCH/PDSCH/CSI-RS with a reception beam/filter same as that for receiving the reference signal, transmitted from Cell 0, according to (or associated with) the second TCI state.

In an example, applying the first TCI state and the second TCI state for uplink transmission may comprise: transmitting (via Cell 1) PUCCH/PUSCH/SRS with a transmission beam/filter same as that for receiving the reference signal, transmitted from Cell 1, according to (or associated with) the first TCI state, and transmitting (via cell 0) PUCCH/PUSCH/SRS with a transmission beam/filter same as that for receiving the reference signal, transmitted from Cell 0, according to (or associated with) the second TCI state.

In the example of FIG. 37, the base station may skip performing the ICBM procedure before transmitting the Layer 1/2 signaling triggering the HO procedure. The base station may skip performing the ICBM procedure, e.g., when beamforming is not used in the target PCell, or if there is no good SSB(s) from the target PCell, or if there are no available radio resources from the target PCell to accommodate the wireless device, or when the wireless device does not support ICBM and/or when the base station does not support ICBM.

In the example of FIG. 37, the source base station may determine to handover the wireless device from the source gNB (Cell 0) to the target gNB (Cell 1). The source base station may determine the handover based on a load/traffic condition, a CSI/beam report of the target gNB, a location/trajectory of the wireless device, a network energy saving strategy (e.g., the source base station determines to turn of the Cell 0 and/or one or more SCells for power saving), etc.

In the example of FIG. 37, the source base station may transmit a second DCI/MAC CE indicating a PCell changing from the current PCell (Cell 0) to a new cell (e.g., Cell 1).

In an example, the new cell may be one of the neighbor (non-serving) cells used in the ICBM procedure (e.g., indicated by the first DCI/MAC CE). The new cell may be cell 1 in the example of FIG. 37. When the ICBM procedure is supported and/or configured, the wireless device, before executing HO procedure indicated by the source base station, has already synchronized with the target gNB regarding which beam should be used for transmission/reception via the target gNB, which is different from layer 3 signaling based (C) HO (as shown in FIG. 32 and/or FIG. 35) where the wireless device needs to synchronize to the target gNB upon executing the HO/CHO and then obtains an indication of a new beam to be used for the target gNB.

In an example, the new cell may be one of a plurality of neighbor (non-serving) cells comprised in L1 beam/CSI report, e.g., with the best measurement report, with the distance closest to the wireless device, etc., when the ICBM procedure is not configured/supported/indicated/activated for the new cell.

In the example of FIG. 37, in response to receiving the second DCI/MAC CE, the wireless device may change the PCell from cell 0 to cell 1. The wireless device may apply the (stored/received) RRC parameters (comprised in RRCReconfiguration, CellGroupConfig, and/or SpCellConfig IE) of the target PCell (cell 1) as the current PCell.

In an example, when the ICBM is configured/supported/indicated/activated before receiving the 2^nd DCI/MAC CE, the wireless device may skip downlink (time/frequency/beam) synchronization (e.g., monitoring MIB/SSB/SIBs and/or selecting a SSB as a reference for downlink reception and/or uplink transmission) in case the wireless device has already synchronized with the target PCell based on the ICBM procedure.

In an example, the wireless device may skip performing RA procedure towards the target PCell before transmitting to and/or receiving from the target PCell, e.g., when the target PCell is close to the source PCell, or the uplink TA is same or similar for the source PCell and the target PCell, or the dedicated RACH resource is not configured in the RRC reconfiguration message of the target PCell.

In an example, the wireless device may perform downlink synchronization (SSB/PBCH/SIBs monitoring) and/or uplink synchronization (RA procedure) for the layer 1/2 signaling based HO (e.g., when ICBM is not configured/indicated/supported/activated) as it does for layer 3 signaling based HO/CHO based on example embodiments described above with respect to FIG. 32, FIG. 33, FIG. 34, FIG. 35 and/or FIG. 36.

FIG. 38 shows an example embodiment of an ICBM procedure. In the example of FIG. 38, a first wireless device (UE1) may be in the coverage of Cell 0 deployed under a first node (e.g., gNB A or TRP A). UE1 is not in the coverage of Cell 1 deployed under a second node (e.g., gNB B or TRP B). Cell 0 and Cell 1 have different PCIs. UE1 may use the RSs (e.g., RS1) transmitted from Cell 0 as a reference RS for a TCI state (which is used for beam/spatial domain filter determination for downlink reception and/or uplink transmission (Tx/Rx based TCI state 0 associated with RS1). UE1 does not use RSs (e.g., RS2 and/or RS3) transmitted from Cell 1 as the reference RS for the TCI state. UE1 configured with a TCI state, associated with a RS of a serving cell with a first PCI and not associated with a RS of another cell with a second PCI different from the first PCI, may be referred to as a UE without (configured/activated) ICBM in this specification.

In the example of FIG. 38, a second wireless device (UE2) may be in the coverage of Cell 0 deployed under a first node (e.g., gNB A or TRP A). UE2 is also in the coverage of Cell 1 deployed under a second node (e.g., gNB B or TRP B). Cell 0 and Cell 1 have different PCIs. UE2 may use the RSs (e.g., RS2) transmitted from Cell 0 as a reference RS for a first TCI state (which is used for beam/spatial domain filter determination for downlink reception and/or uplink transmission via Cell 0 (Tx/Rx based TCI state 1 associated with RS2). UE2 also uses RSs (e.g., RS3) transmitted from Cell 1 as the reference RS for a second TCI state (which is used for beam/spatial domain filter determination for downlink reception and/or uplink transmission via Cell 1 (Tx/Rx based TCI state 2 associated with RS3). UE2 configured with a first TCI state, associated with a RS of a serving cell with a first PCI and configured with a second TCI state associated with a RS of another cell with a second PCI different from the first PCI, may be referred to as a UE with (configured/activated) ICBM in this specification.

In an example, when gNB B or TRP B receives uplink signals/channels with the second TCI state, it may forward the uplink signals/channels to gNB A or TRPA for processing.

In an example, gNB A or TRP A may forward downlink signals/channels to gNB B or TRP B to transmit with the second TCI state to the wireless device.

In the ICBM procedure of FIG. 38, Cell 1 with the second PCI different from the first PCI of Cell 0 may be considered/configured as a part (e.g., a second TRP with a second PCI different from a first PCI of a first TRP) of cell 0 for UE2, e.g., based on example embodiments described above with respect to FIG. 31B. Cell 0 and Cell 1 may belong to a same DU (or gNB-DU) when Cell 1 is configured as the part of Cell 0. A gNB-DU may be implemented based on example embodiments described above with respect to FIG. 1A and/or FIG. 1B. The PDCCH/PDSCH/PUCCH/PUSCH resources are shared between Cell 1 and Cell 0 in a way that is transparent to UE2. However, SSBs/CSI-RSs of Cell 0 do not share the same resources with SSBs/CSI-RSs of Cell 1. SSBs/CSI-RSs of Cell 0 may have configuration parameters (e.g., number of beams, periodicity, transmission power, etc.) different than configuration parameters of SSBs/CSI-RSs of Cell 1.

In an example, Cell 1 with the second PCI different from the first PCI of Cell 0 may be considered/configured as a separate cell different from cell 0 for UE2, e.g., when Cell 1 is configured as a candidate target cell based on example embodiments described above with respect to FIG. 33 and/or FIG. 36. Cell 0 and Cell 1 may belong to different DUs (or gNB-DUs) associated with a same CU (or gNB-CU) or different CUs when Cell 1 is configured as a separate cell from Cell 0. A gNB-DU and/or a gNB-CU may be implemented based on example embodiments described above with respect to FIG. 1A and/or FIG. 1B. Cell resources (SSB/CSI-RS/PDCCH/PDSCH/PUCCH/PUSCH) are not shared between Cell 1 and Cell 0. Cell 1 has configuration parameters of the cell resources, different from (or independent of) configuration parameters of the cell resources of Cell 0.

In existing technologies, network energy saving operation may comprise shutting down some cells or reducing periodicity of SSB/SIB1/SIB2 with or without beam sweeping, which may be different from the power saving operations for a wireless device. Shutting down cells (entirely or partially) may lead to negative impact on data transmission latency and/or power consumption during the access process. Another option may comprise modifying existing SSB towards a lighter version by carrying no or minimal info, such as PSS for example, which may be called as “light SSB”. This “light SSB” could be combined with other techniques such as less frequent SSB transmission (e.g., with a periodicity >20 msec), or with “on-demand SSB”; where “on-demand SSB” is the SSB transmission that is triggered by UE via an UL trigger signal. As an example, a base station may transmit this “light SSB” and if there are wireless devices monitoring this “light SSB” and trying to access the network, the wireless devices may react by transmitting an uplink trigger signal. Upon reception of the uplink trigger signal, the base station may start transmitting the full-blown SSB. In an example, after receiving the uplink trigger signal, the network can adjust the SSB transmission configuration to respond to the wireless device's indication.

In an example, a base station may perform network energy saving operation when carrier aggregation (CA) is supported. In CA operation, a wireless device may be configured with a set of secondary cells (SCell) in addition to a primary cell (PCell). In existing technologies, PCell/SCell configurations are UE-specific configured. A CC configured as a PCell for a wireless device may be (separately and/or independently) configured as a SCell for another wireless device. From network power consumption perspective, it is beneficial to turn off some CCs and keep a common CC serving as PCell for UEs in RRC_CONNECTED state when the cell load is low. To achieve this goal, a base station may request the wireless device to perform PCell switch when the ongoing CC serving as PCell is not the common CC serving as PCell for the purpose of network power savings. After switching to a new PCell, the gNB may deactivate the old PCell or send/transition it to a dormant state. In existing technologies, PCell switch is achieved by L3-based HO/CHO (as shown in FIG. 32 and/or FIG. 35). However, the RRC reconfiguration may not be fast enough to react to dynamic arrival load. To improve network energy saving, dynamic PCell switching based on UE-specific DCI or group common DCI has been proposed.

FIG. 39 shows an example embodiment of dynamic PCell switching for network energy saving. In an example, a first wireless device (e.g., UE1) may be configured with a plurality of cells comprising a PCell (e.g., 1^st cell located in frequency point F2) and a SCell (e.g., 2^nd cell located in frequency point F1). A second wireless device (e.g., UE2) may be configured with a plurality of cells comprising a PCell (e.g., 2^nd cell located in frequency point F1) and a SCell (e.g., 1^st cell located in frequency point F2). The PCell of UE1 may be served/configured as a SCell for UE 2. The PCell of UE2 may be served/configured as a SCell for UE1.

In an example, a PCell is a cell where the base station may transmit NAS related information (e.g., mobility) and/or security related information to a wireless device. The PCell is also a cell where the base station may maintain an RRC connection with the wireless device. Via the PCell (instead of a SCell), the wireless device performs an initial (RRC) connection establishment procedure or initiates a (RRC) connection re-establishment procedure.

In a non-energy-saving state, the base station may use 1^st cell as PCell and/or use 2^nd cell as SCell to communicate with UE1. In the non-energy-saving state, the base station may use 2^nd cell as PCell and/or use 1^st cell as SCell to communicate with UE2. Using different PCells to serve different wireless devices may balance signaling overhead for different cells.

In an example, to achieve dynamic PCell switching for network energy saving, the base station may transmit a L1 signaling (e.g., a group common DCI or a UE-specific DCI) indicating a PCell switching for UE1 and/or other UEs. The L1 signaling may indicate to UE1 that PCell is switched from 1^st cell to 2^nd cell for UE1 and/or SCell is switched from 2^nd cell to 1^st cell. In response to receiving the L1 signaling, UE1 may switch the PCell and the SCell. After switching the PCell and the SCell, UE1 and UE2 are now served with the same cell (e.g., 2^nd cell) as the PCell. The same PCell for UE1 and UE2 may be referred to as a group common PCell. Based on UE1 and UE2 being served with the same PCell, the base station may deactivate (transition to dormancy or turn off) 1^st cell without connection lost with UE1 and UE2.

In an example, when the base station is medium or heavily loaded (e.g., with more than 5 or 10 wireless devices connected to the base station), for enabling the network energy saving, the base station may use a group common DCI indicating, for a plurality of wireless devices, a PCell changing/switching to a common PCell.

In an example, when the base station is light loaded (e.g., with one or two wireless devices connected to the base station), for enabling the network energy saving, the base station may use the UE-specific DCI/MAC CE (to each wireless device) indicating a PCell changing/switching, e.g., based on example embodiments described above with respect to FIG. 43, e.g., if the current PCell of each wireless device is not a common PCell of the base station.

Based on example of FIG. 39, dynamic PCell switching may allow the base station to turn off some cells without RRC connection lost with wireless devices.

In existing technologies, a base station configures, for a wireless device, RRC configuration parameters (SSBs, RACH resources, MAC parameters, PHY cell common and/or UE-specific parameters, as shown in FIG. 33, FIG. 34 and/or FIG. 36) of a target PCell for performing (C) HO to the target PCell from a source PCell. When performing the (C) HO to the target PCell, the wireless device applies the received/stored RRC configuration parameters. The wireless device starts to perform downlink synchronization towards the target PCell (e.g., time/frequency alignment by monitoring the SSBs configured on the target PCell, e.g., according to 3GPP TS 38.213 Section 4-Synchronization procedures). After the downlink synchronization is complete, the wireless device starts to perform uplink synchronization, e.g., by initiating a (CF) RA procedure based on the RACH resources configured on the target PCell. The wireless device receives a time alignment (TA) command in a RAR corresponding to a preamble transmitted by the wireless device.

In existing technologies, for transmitting a preamble for the CFRA procedure, when multiple beams are used for SSB transmissions (e.g., based on example embodiments described above with respect to FIG. 29 and/or FIG. 30) by the base station, the wireless device may select, based on a RSRP value of a first SSB being greater than a RSRP threshold, the first SSB from a plurality of candidate SSBs configured in the RACH resources (e.g., based on example embodiments described above with respect to FIG. 34) on the target PCell. The wireless device determines the preamble with a preamble index associated with the selected first SSB according to RACH resource configuration parameters. After selecting the first SSB, the wireless device determines a next available PRACH occasion from PRACH occasions corresponding to the selected first SSB permitted by the restrictions given by the ra-ssb-OccasionMaskIndex configured in the rach-ConfigDedicated IE as shown in FIG. 34. The wireless device transmits the preamble via the determined PRACH occasion to the target PCell. The wireless device monitors a PDCCH of the target PCell for receiving a RAR corresponding to the preamble. The wireless device receives the RAR comprising the preamble index and/or a TA command. The wireless device completes the CFRA procedure. The CFRA procedure may be implemented based on example embodiments described above with respect to FIG. 13B. After completing the CFRA procedure, the wireless device may receive, from the target PCell, a beam indication (or a TCI state indication) used for PDCCH/PDSCH/CSI-RS reception and/or PUCCH/PUSCH/SRS transmission for the target PCell. The wireless device may apply the beam (or the TCI state) for PDCCH/PDSCH/CSI-RS reception and/or PUCCH/PUSCH/SRS transmission for the target PCell.

In existing technologies, the wireless device, after receiving a HO command (e.g., RRC reconfiguration with a ReconfigurationWithSync IE), performs downlink synchronization and uplink synchronization, beam alignment/management via a target PCell. Performing downlink synchronization, uplink synchronization and/or beam alignment may be time consuming.

FIG. 40A shows an example of timeline of layer 3 based HO procedure. In an example, when a wireless device receives a HO command (e.g., a RRC reconfiguration message based on example embodiments described above with respect to FIG. 32, FIG. 33 and/or FIG. 34), the wireless device may spend around 10 ms for RRC message processing (PDCCH/PDSCH decoding, ACK/NACK feedback etc.) and then spend 20 ms for UE processing (e.g., loading RRC/MAC/PHY related parameters to memory unit of the wireless device, etc.). This process of RRC message processing and UE processing may be referred to as UE reconfiguration. Then the wireless device may spend more than 20 ms for searching for a first SSB (T first-SSB) and may need additional 2 ms for processing the SSB (T SSB-processing). The SSB searching and processing may be referred to as downlink (DL) synchronization. The wireless device may spend around 20 ms for uplink (UL) synchronization comprising a first time period of an interruption uncertainty (Tu) in acquiring a first available PRACH occasion for a preamble transmission in the target cell, a second time period used for PRACH transmission, a third time period (4 ms in FIG. 40A) for monitoring PDCCH for receiving a RAR corresponding to the preamble transmission, and/or receiving/decoding the RAR. TIu (15 ms in FIG. 40A) can be up to the summation of SSB to PRACH occasion association period and 10 ms. There may be additional time period for processing and coding a RRC message for a HO complete indication. Existing HO procedure may increase PCell switching latency.

FIG. 40B shows an example of timeline of layer 1/2 triggered HO procedure for mobility management and/or network energy saving. In an example, before a wireless device receives a HO command (e.g., a Layer 1/2 command based on example embodiments described above with respect to FIG. 37 and/or FIG. 39), the wireless device may receive a RRC reconfiguration message (e.g., Pre-Config in FIG. 40B). The wireless device may spend 10 ms for RRC processing.

In an example of FIG. 40B, the base station may transmit a layer 1/2 command indicating a PCell switching, e.g., based on example embodiments described above with respect to FIG. 37 (e.g., without ICBM configured/activated), after transmitting the RRC reconfiguration message. In response to receiving the layer 1/2 command indicating the PCell switching, the wireless device may perform DL synchronization and/or UL synchronization. After completing the DL/UL synchronization, the wireless device may receive a TCI state indication of the new PCell for PDCCH/PDSCH reception and/or PUCCH/PUSCH transmission via the new PCell. In an example, the wireless device may conduct UE reconfiguration after completing the DL/UL synchronization. When the wireless device supports the UE reconfiguration after receiving the RRC reconfiguration message, the UE reconfiguration may be conducted upon receiving the RRC reconfiguration message, rather than after completing the DL/UL synchronization. The latency for HO to the new PCell in this case comprises DL synchronization, UL synchronization, and TCI state indication and/or application.

In an example, the wireless device, after receiving the cell switch command, may perform UL synchronization by conducting RACH procedure, e.g., based on example embodiments described above with respect to FIG. 13A, FIG. 13B and/or FIG. 13C. The performing UL synchronization may comprise (e.g., based on example of FIG. 40A and/or FIG. 40B), transmitting a preamble via an active uplink BWP (e.g., a BWP configured as firstActiveUplinkBWP-id as shown in FIG. 33) of uplink BWPs of the target PCell, monitoring PDCCH on an active downlink BWP (e.g., a BWP configured as firstActiveDownlinkBWP-id as shown in FIG. 33) of the target PCell for receiving a RAR comprising a TA which is used for PUSCH/PUCCH transmission via the target PCell, receiving the RAR and/or obtaining the TA. The wireless device may activate the uplink BWP configured with firstActiveUplinkBWP-id and the downlink BWP configured with firstActiveDownlinkBWP-id on the target PCell upon performing HO to the target PCell. After completing the UL synchronization, the wireless device obtains the TA to be used for PUSCH/PUCCH transmission via the target PCell. The wireless device, by using the TA to adjust uplink transmission timing, and then transmit PUSCH/PUCCH via the target PCell based on the adjusted timing. The adjusting uplink transmission timing may comprise advancing or delaying the transmissions by an amount indicated by a value of the TA, e.g., to ensure the uplink signals received at the target PCell are aligned (in time domain) with uplink signals transmitted from other wireless devices.

To further reduce HO latency, especially the latency introduced for uplink synchronization, an early TA acquisition scheme is proposed. FIG. 41 shows an example of early TA acquisition (or ETA)-based HO procedure.

In an example, as shown in FIG. 41, the network (e.g., a base station, a source gNB) may configure the wireless device to perform measurement reporting (possibly including the configuration of measurement gaps) for a plurality of neighbor cells (e.g., Cell 1 from a candidate target gNB 1, Cell 2 from a candidate target gNB 2, etc.). The measurement reporting is a layer 3 reporting, different from layer 1 CSI reporting. The wireless device may transmit one or more measurement reports to the source gNB (or source PCell, cell 0 in FIG. 41).

As shown in FIG. 41, based on the one or more measurement reports from the wireless device, the source gNB may provide the target gNB with a list of best cells on each frequency for which measurement information is available, for example, in order of decreasing RSRP. The source gNB may also include available measurement information for the cells provided in the list. The target gNB may decide which cells are configured for use (as a target PCell, and/or one or more SCells) after HO, which may include cells other than the ones indicated by the source gNB.

In an example, as shown in FIG. 41, the source gNB may transmit a HO request to the target gNB. The target gNB may response with a HO message. In an example, in the HO message, the target gNB may indicate access stratum configuration (e.g., RRC configurations of the target cells) to be used in the target cell(s) for the wireless device.

In an example, the source gNB may transparently (for example, does not alter values/content) forward the HO (e.g., contained in RRC reconfiguration messages of the target gNB, cell group configuration IE of the target gNB, and/or SpCell configuration IE of a target PCell/SCells of the target gNB) message/information received from the target gNB to the wireless device.

In an example, the source gNB may configure a Layer 1/2 signaling based HO (PCell switching/changing, mobility, etc.) procedure different from a normal HO procedure (e.g., as shown in FIG. 32, FIG. 33 and/or FIG. 34) and/or a CHO procedure (e.g., as shown in FIG. 35 and/or FIG. 36), by comprising a Layer 1/2 candidate PCell configuration message (e.g., a newly defined candidates-L1L2-Config IE) in RRC reconfiguration message of the source gNB. The Layer 1/2 candidate PCell configuration message may comprise a list of candidate target PCells, each candidate target PCell being associated with dedicated RACH resources for the RA procedure in case a Layer 1/2 signaling based HO is trigged by a Layer 1/2 signaling and executed to the candidate target PCell, etc. There may be multiple options for parameter configurations of a candidate target PCell.

In an example, as a first option for the parameter configuration, for each candidate target PCell, the RRC reconfiguration message of the source gNB may comprise a (capsuled) RRC reconfiguration message (e.g., RRCReconfiguration), of a candidate target gNB, received by the source gNB from a candidate target gNB via X2/Xn interface. The (capsuled) RRC reconfiguration message, of the candidate target gNB, may reuse the same signaling structure of the RRC reconfiguration message of the source gNB, as shown in FIG. 33 and/or FIG. 34.

In an example, as a second option for the parameter configuration, for each candidate target PCell, the RRC reconfiguration message of the source gNB may comprise a (capsuled) cell group configuration message (e.g., CellGroupConfig), of a candidate target gNB, received by the source gNB from a candidate target gNB via X2/Xn interface. The (capsuled) cell group configuration message, of the candidate target gNB, may reuse the same signaling structure of the cell group configuration message of the source gNB, as shown in FIG. 33 and/or FIG. 34. The second option may reduce signaling overhead of the parameter configuration of a candidate target PCell compared with the first option.

In an example, as a third option for the parameter configuration, for each candidate target PCell, the RRC reconfiguration message of the source gNB may comprise a (capsuled) SpCell configuration message (e.g., SpCellConfig), of a candidate target gNB, received by the source gNB from a candidate target gNB via X2/Xn interface. The (capsuled) SpCell configuration message, of the candidate target gNB, may reuse the same signaling structure of the SpCell configuration message of the source gNB, as shown in FIG. 33 and/or FIG. 34. The third option may reduce signaling overhead of the parameter configuration of a candidate target PCell compared with the second option.

In an example, for each candidate target PCell, the source gNB may indicate cell common and/or UE specific parameters (e.g., SSBs/CSI-RSs, BWPs, RACH resources, PDCCH/PDSCH/PUCCH/PUSCH resources etc.).

In an example, Cell 0, Cell 1 and/or Cell 2 may belong to a same gNB-DU, in which case, Cell 1 and/or Cell 2 may be configured as a part of Cell 0 which is a serving cell. The radio resources (PDCCH, PDSCH etc.) of Cell 0 are shared with Cell 1 and/or Cell 2. Cell 1 and/or Cell 2 may transmit SSBs different from SSBs transmitted via Cell 0, e.g., based on example of FIG. 38. A gNB-DU may be implemented based on example embodiments described above with respect to FIG. 1A and/or FIG. 1B.

In an example, Cell 0, Cell 1 and/or Cell 2 may belong to different gNB-DUs (which are associated with a same gNB-CU or associated with different gNB-CUs), in which case, Cell 1 and/or Cell 2 may be configured as separate cells (non-serving cell) from Cell 0. The radio resources (PDCCH, PDSCH etc.) of Cell 0 are not shared with Cell 1 and/or Cell 2. Cell 1 and/or Cell 2 may transmit SSBs different from SSBs transmitted via Cell 0, e.g., based on example of FIG. 38. A gNB-DU and/or a gNB-CU may be implemented based on example embodiments described above with respect to FIG. 1A and/or FIG. 1B.

In the example of FIG. 41, the wireless device, according to the received RRC reconfiguration messages comprising parameters of a Layer 1/2 signaling based HO procedure, may perform Layer 1/2 measurement report (CSI/beam) for the list of candidate target PCells and/or the current PCell. The layer 1/2 measurement report may comprise layer 1 RSRP, layer 1 RSRQ, PMI, RI, layer 1 SINR, CQI, etc.

In an example, the layer 1/2 measurement report may be triggered when the measurement of the CSI/beam of a candidate target PCell is greater than a threshold, or (amount of offset) greater than the current PCell, etc.

In an example, the layer 1/2 measurement report may be transmitted with a periodicity configured by the source gNB.

In an example, the layer 1/2 measurement report may be contained in a UCI via PUCCH/PUSCH, or a MAC CE (e.g., event-triggered, associated with a configured SR for the transmission of the MAC CE).

In the example of FIG. 41, the wireless device may determine that Cell 1 has better channel quality than Cell 0. The wireless device may transmit the layer 1/2 measurement report indicating that Cell 1 has better channel quality than Cell 0. The source base station and the target base station may determine which cell is used as the target PCell. The source base station, upon receiving the layer 1/2 measurement report, may coordinate with the candidate target base station regarding whether Cell 1 could be used as a candidate target PCell for future HO.

In the example of FIG. 41, when determining Cell 1 is used as the target PCell for future HO, the source base station (e.g., according to the request of the target base station if there is no time alignment obtained before for Cell 1), may transmit, from Cell 0 (or an activated SCell of the wireless device) a first layer 1/2 (1^st L1/2) command (e.g., a DCI/MAC CE/RRC message) triggering a preamble transmission (RACH, or other uplink signals like SRS) towards Cell 1. The DCI may be based on a PDCCH order in existing technology.

In the example of FIG. 41, the wireless device, upon receiving the first layer 1/2 command, may transmit the preamble (or SRS which is not shown in FIG. 41) to the target PCell (Cell 1). The target base station may monitor PRACH occasion for receiving the preamble to estimate the TA used for future uplink transmission from the wireless device after the wireless device switches the PCell from Cell 0 to Cell 1.

In the example of FIG. 41, the target base station may forward the estimated TA for Cell 1 to the source base station.

In the example of FIG. 41, the source base station may transmit the forwarded TA to the wireless device, e.g., via a RAR message, or via a TAC MA CE. In this case, the wireless device may monitor PDCCH (on Cell 0) for receiving the RAR message based on existing technologies (e.g., based on example embodiments described above with respect to FIG. 13A, FIG. 13B and/or FIG. 13C). The wireless device may maintain a TAT for a TAG associated with Cell 1. The wireless device may maintain Cell 1 as a non-serving cell. The TAC MAC CE may indicate (e.g., one or more bitfields of the MAC CE) whether the TAC is for a serving cell (or a TAG associated with the serving cell) or for a non-serving cell (e.g., Cell 1).

In an example, the source base station may skip transmitting the forwarded TA to the wireless device. Instead, the source base station may indicate the TA together with a second layer 1/2 command indicating/triggering PCell switching from Cell 0 to Cell 1. In this case, the wireless device may skip monitoring PDCCH (on Cell 0) for receiving the RAR message.

In the example of FIG. 41, the transmission of a preamble to a candidate target PCell, before receiving a (P) Cell switch command (with or without comprising a TA estimated by the target base station for the target PCell) indicating to switch the PCell to the target PCell, is referred to as an early TA acquisition (ETA) procedure/process/feature/scheme in this specification. By implementing the ETA, before the wireless device performs the HO, the target base station may obtain the TA to be used by the wireless device after performing the HO to the target PCell. The TA for the target PCell may be transmitted in a RAR or combined together with the L1/2 (or L1/L2) command indicating the PCell switching. Compared with the timelines shown in FIG. 40A and/or FIG. 40B, the wireless device may skip the RA procedure after receiving the L1/2 command indicating the PCell switching based on the TA for the target PCell already being obtained by the ETA procedure. The ETA procedure therefore reduces the latency for uplink synchronization with the target PCell upon performing HO procedure (or PCell switching procedure).

In the example of FIG. 41, the wireless device may receive a second L1/2 command indicating the PCell switching from Cell 0 to Cell 1. The second L1/2 command may further indicate the TA (forwarded from the target base station to the source base station and used for the target PCell in future), e.g., if the TA is not received before receiving the second L1/2 command. In response to receiving the second L1/2 command, the wireless device may switch the PCell from Cell 0 to Cell 1 and transmit PUSCH/PUCCH via Cell 1 based on the TA. Switching the PCell from Cell 0 to Cell 1 may comprise at least one of: applying RRC configuration parameters of Cell 1, stopping applying RRC configuration parameters of Cell 0, resetting/reconfiguring MAC entity, receiving RRC messages/MIB/SSBs/SIBs/PDCCHs/PDSCHs from Cell 1 and stopping receiving RRC messages/MIB/SSBs/SIBs/PDCCHs/PDSCHs from Cell 0.

In an example, a PCell switch procedure based on a L1/2 command (e.g., combined with an ETA procedure) may be referred to as a L1/2 triggered mobility (LTM) procedure, based on example embodiments described above with respect to FIG. 41.

In existing technologies, a wireless device may activate a downlink BWP (e.g., with a BWP ID configured as firstActiveDownlinkBWP-id) of a plurality of downlink BWPs of a target PCell and an uplink BWP (e.g., with a BWP ID configured as firstActiveUplinkBWP-id) of a plurality of uplink BWPs of a target PCell in response to performing RRC reconfiguration (e.g., triggered by receiving RRC reconfiguration message comprising a ReconfigurationWithSync IE, or triggered by receiving a L1/2 cell switch command), e.g., based on example embodiments described above with respect to FIG. 32, FIG. 40A, FIG. 40B, and/or FIG. 41. The L1/2 cell switch command may be (equivalently) referred to as a L1/2 PCell switch command, L1/2 handover command, L1/2 cell switching indication, etc., in this specification. The L1/2 cell switch command may be a DCI or a MAC CE. The L1/2 cell switch command is different from a DCI indicating cross-carrier scheduling which does not involve PCell switching. The L1/2 cell switch command is different from a DCI indicating active BWP switching which does not involve PCell switching. After activating the downlink BWP of the target PCell, the wireless device may perform downlink reception (e.g., MIB/SIB/PDCCH/PDSCH/CSI-RS) via the target PCell. After activating the uplink BWP of the target PCell, the wireless device may perform a RA procedure to obtain TA for the target PCell.

In existing technologies, a wireless device may determine a transmission power for a PRACH, P_PRACH,b,f,c(i), on active UL BWP b of carrier f of serving cell c based on DL RS for serving cell c in transmission occasion i as

$P_{\mathrm{PRACH},b,f,c}\left(i\right)=\min \left\{P_{\mathrm{CMAX},f,c}\left(i\right),P_{\mathrm{PRACH},\mathrm{target},f,c}+{\mathrm{PL}}_{b,f,c}\right\}\left[\mathrm{dBm}\right]$

where P_CMAX,f,c(i) is the wireless device configured maximum output power (e.g., defined in 3GPP TS 38.101-1, 3GPP TS 38.101-2 and 3GPP TS 38.101-3) for carrier f of serving cell c within transmission occasion i, P_{PRACH,target,f,c} is the PRACH target reception power PREAMBLE_RECEIVED_TARGET_POWER provided by higher layers (e.g., in 3GPP TS 38.321) for the active UL BWP b of carrier f of serving cell c, and PL_b,f,c is a pathloss for the active UL BWP b of carrier f based on the DL RS associated with the PRACH transmission on the active DL BWP of serving cell c and calculated by the UE in dB as referenceSignalPower-higher layer filtered RSRP in dBm, where RSRP is measured by the wireless device (e.g., based on 3GPP TS 38.215) and the higher layer filter configuration is defined in 3GPP TS 38.331. If the active DL BWP is the initial DL BWP and for SS/PBCH block and CORESET multiplexing pattern 2 or 3, the wireless device determines PL_b,f,c based on the SS/PBCH block associated with the PRACH transmission.

In an example, a wireless device may measure a SS-RSRP as a linear average over power contributions (in [W]) of resource elements that carry secondary synchronization signals (SSSs). The measurement time resource(s) for SS-RSRP are confined within SS/PBCH Block Measurement Time Configuration (SMTC) window duration. If SS-RSRP is used for L1-RSRP as configured by reporting configurations, the measurement time resources(s) restriction by SMTC window duration is not applicable.

In an example, a wireless device may use DM-RSs for PBCH and CSI-RSs in addition to SSSs if indicated by higher layers, for SS-RSRP determination/measurement. SS-RSRP using DM-RSs for PBCH or CSI-RSs is measured by linear averaging over power contributions of resource elements that carry corresponding RSs taking into account power scaling for the RSs as defined in TS 38.213. If SS-RSRP is not used for L1-RSRP, the additional use of CSI-RSs for SS-RSRP determination is not applicable.

In an example, for frequency range 1, the reference point for the SS-RSRP is the antenna connector of the wireless device. For frequency range 2, SS-RSRP is measured based on the combined signal from antenna elements corresponding to a given receiver branch. For frequency range 1 and 2, if receiver diversity is in use by the wireless device, the reported SS-RSRP value may not be lower than the corresponding SS-RSRP of any of the individual receiver branches.

In an example, SS-RSRP is measured only among the RSs corresponding to SS/PBCH blocks with the same SS/PBCH block index and the same physical-layer cell identity.

In an example, If SS-RSRP is not used for L1-RSRP and higher-layers indicate certain SS/PBCH blocks for performing SS-RSRP measurements, then SS-RSRP is measured only from the indicated set of SS/PBCH block(s).

In an example, if a PRACH transmission from a wireless device is not in response to a detection of a PDCCH order by the wireless device, or is in response to a detection of a PDCCH order by the wireless device that triggers a contention based random access procedure, or is associated with a link recovery procedure where a corresponding index q_new is associated with a SS/PBCH block, the wireless device determines that reference SignalPower is provided by ss-PBCH-BlockPower of the SSB/PBCH block.

In an example, if a PRACH transmission from a wireless device is in response to a detection of a PDCCH order by the wireless device that triggers a contention-free random access procedure and depending on the DL RS that the DM-RS of the PDCCH order is quasi-collocated, reference SignalPower is provided by ss-PBCH-BlockPower for the DL RS or, if the wireless device is configured resources for a periodic CSI-RS reception or the PRACH transmission is associated with a link recovery procedure where a corresponding index q_new is associated with a periodic CSI-RS configuration, referenceSignalPower is obtained by ss-PBCH-BlockPower and powerControlOffsetSS where powerControlOffsetSS provides an offset of CSI-RS transmission power relative to SS/PBCH block transmission power. If powerControlOffsetSS is not provided to the wireless device, the wireless device assumes an offset of 0 dB. If the active TCI state for the PDCCH that provides the PDCCH order includes two RSs, the wireless device expects that one RS is configured with qcl-Type set to ‘typeD’ and the wireless device uses the one RS when applying a value provided by powerControlOffsetSS.

In an example, if within a random access response window, the wireless device does not receive a random access response that contains a preamble identifier corresponding to the preamble sequence transmitted by the wireless device, the wireless device determines a transmission power for a subsequent PRACH transmission.

In an example, if prior to a PRACH retransmission, a wireless device changes the spatial domain transmission filter, Layer 1 notifies higher layers to suspend the power ramping counter.

In an example, if due to power allocation to PUSCH/PUCCH/PRACH/SRS transmissions, or due to power allocation in EN-DC or NE-DC or NR-DC operation, or due to slot format determination, or due to the PUSCH/PUCCH/PRACH/SRS transmission occasions are in the same slot or the gap between a PRACH transmission and PUSCH/PUCCH/SRS transmission is small, the wireless device does not transmit a PRACH in a transmission occasion, Layer 1 notifies higher layers to suspend the corresponding power ramping counter. If due to power allocation to PUSCH/PUCCH/PRACH/SRS transmissions, or due to power allocation in EN-DC or NE-DC or NR-DC operation, the wireless device transmits a PRACH with reduced power in a transmission occasion, Layer 1 may notify higher layers to suspend the corresponding power ramping counter.

In existing technologies, a wireless device determines a transmission power, of a preamble (via a serving cell) triggered by a PDCCH order, based on a reference signal transmission power (reference SignalPower) of a DL RS quasi-collocated (QCLed) with a DM-RS of the PDCCH order. The DL RS may be SSB or a CSI-RS. The DL RS may be associated with a PCI (physical cell identifier) of a serving cell or a PCI (which may be referred to as an additional PCI) different from the PCI of the serving cell, e.g., based on configuration parameters of the serving cell (e.g., SSB-MTC-AddtionalPCI-r17 IE in 3GPP TS 38.331 V17.2.0).

In an example, if the DM-RS of the PDCCH order is QCLed with a SSB associated with a PCI of the serving cell, the wireless device determines the referenceSignalPower, of the SSB of the serving cell, as a value of ss-PBCH-BlockPower IE configured in ServingCellConfigCommon IE (or ServingCellConfigCommonSIB IE) of the serving cell. QCL relation between a DM-RS of a DCI (e.g., PDCCH order) and a SSB (or a CSI-RS) may be configured, activated/deactivated by RRC message, MAC CE and/or DCI, based on example embodiments described above with respect to FIG. 31A and/or FIG. 31B.

In an example, if the DM-RS of the PDCCH order is QCLed with a SSB associated with the additional PCI of the serving cell, the wireless device determines the referenceSignalPower of the SSB, as a value of ss-PBCH-BlockPower IE configured in SSB-MTC-AddtionalPCI-r17 IE comprised in ServingCellConfig IE of the serving cell.

To perform early TA acquisition for a candidate target PCell for reducing cell switching latency, a wireless device may receive a PDCCH order, via a source PCell, triggering a preamble transmission via the candidate target PCell, e.g., based on the example of FIG. 41. The candidate target PCell may be associated with a first gNB-DU different from a second gNB-DU of the source PCell. The candidate target PCell may be associated with a first gNB-CU different from a second gNB-CU of the source PCell. The candidate target PCell may be a non-serving cell. This candidate target PCell and the source PCell is different from a Rel. 17 ICBM scenario (e.g., as shown in FIG. 37 and/or FIG. 38) in which Cell 0 and Cell 1 belong to a same gNB-DU, which allows the base station to transmit the PDCCH order (and/or other DCIs) either via Cell 0 (e.g., via a first CORESET with a first TCI state associated with the PCI of Cell 0) or via Cell 1 (e.g., via second CORESET with a second TCI state associated with the additional PCI of Cell 0).

In an example, when the candidate target PCell and the source PCell do not belong to a same gNB-DU in a fast cell switching scenario (e.g., as shown in FIG. 41), or when the candidate target PCell is a non-serving cell, TCI states and/or CORESET/SSs configuration associated with the candidate target PCell are not available to use (or to apply) by the base station and/or the wireless device before the wireless device performs (e.g., completes) the cell switching to the candidate target PCell, in which case the base station transmits the PDCCH order (indicating a preamble transmission via the candidate target PCell) via the source PCell (or any activated SCell), not via the candidate target PCell. In this case, the wireless device, by implementing existing technologies, may have difficulties in determining an uplink transmission power of the preamble given that none of downlink BWPs of the candidate target PCell is in an activated state before switching to the candidate target PCell as the PCell in the LTM procedure. Existing technologies are not applicable to the candidate target PCell which is a non-serving cell before the cell switch. Misalignment between the wireless device and the target base station may occur regarding which reference signals are used for pathloss calculation, which DL BWP is used to determine a reference signal transmission power, which parameters are used to determine a preamble target power, which parameters are used to determine a transmission power of the reference signals, etc. Existing technologies may increase power consumption of the wireless device for the preamble transmission or result in insufficient transmission power for the preamble transmission. The target base station may mis-detect the preamble which may result in a failure of the ETA procedure. There is a need to improve uplink preamble transmission power control scheme where the preamble is triggered by a PDCCH order received via a source PCell and is transmitted via a candidate target PCell before receiving a cell switch command indicating to switch from the source PCell to the candidate target PCell as a PCell.

In an example embodiment, a wireless device receives, via a source PCell, a PDCCH order (or a DCI) triggering a transmission of a preamble via a candidate target PCell for a L1/2 triggered mobility (LTM) procedure. The transmission of the preamble may be for early TA acquisition for the candidate target PCell before the wireless device receives a cell switch command indicating to switch from the source PCell to the candidate target PCell as the PCell. The wireless device determines a RS of the candidate target PCell as a pathloss reference for uplink transmission power calculation of the preamble. Different from existing technologies where the wireless device uses a RS, of a serving cell (e.g., where the wireless device receives a PDCCH order or where the preamble is transmitted), as a pathloss reference for uplink transmission power calculation of a preamble triggered by the PDCCH order, example embodiment may enable the wireless device to determine a correct (e.g., more accurate or relevant) RS for the uplink transmission power calculation for the preamble. The wireless device may use the RS of the candidate target PCell (which is a non-serving cell) to determine a pathloss for the preamble transmission based on a SSB transmission power of the RS and/or a L1/3 filtered RSRP of the RS.

In an example embodiment, the wireless device, based on the PDCCH order triggering the transmission of the preamble via the candidate target PCell, selects from SSBs of the candidate target PCell, a SSB of the candidate target PCell as the pathloss RS, based on the SSB overlapping with (on at least one RE/RB in frequency domain) an active DL BWP of a source PCell, an active DL BWP of a SCell (e.g., in active state or in deactivated state), and/or a configured DL BWP of the source PCell or the SCell. Example embodiment, by using the SSB, of the candidate target PCell, overlapping with the source PCell or the SCell in frequency domain, may ensure that the wireless device obtains correct pathloss based on measurement of the SSB. Example embodiments may reduce power consumption of the wireless device, and/or improve transmission reliability for the preamble via the candidate target PCell.

In an example embodiment, the wireless device may select from more than one SSB, of the candidate target PCell, overlapping with (on at least one RE/RB in frequency domain) an active DL BWP of a source PCell, an active DL BWP of a SCell (e.g., in active state or in deactivated state), and/or a configured DL BWP of the source PCell or the SCell, a SSB of the candidate target PCell as the pathloss RS, based on the SSB having the lowest SSB index, the highest RSRP value and/or a RSRP value greater than a RSRP threshold (configured in configuration parameters of the candidate target PCell in one or more RRC message) among the more than one SSB. Example embodiments may reduce power consumption of the wireless device, and/or improve transmission reliability for the preamble via the candidate target PCell.

In an example embodiment, the wireless device, based on the PDCCH order triggering the transmission of the preamble via the candidate target PCell, may determine the RS of the candidate target PCell, for the uplink transmission power determination of the preamble, as a first RS, of a plurality of RSs of the candidate target PCell, indicated by the PDCCH order. The PDCCH order may comprise an SSB index indicating the first RS of the plurality of RSs of the candidate target PCell. The wireless device may further determine a PRACH occasion and/or a preamble index of the preamble for the preamble transmission based on the SSB index.

In an example embodiment, the wireless device, based on the PDCCH order triggering the transmission of the preamble via the candidate target PCell, may determine the RS of the candidate target PCell as a first RS of a plurality of RSs of the candidate target PCell for which the wireless device transmits a L1/2 CSI (beam, channel measurement etc.) report for the candidate target PCell for a LTM procedure. The L1/2 CSI report for a LTM procedure may be transmitted (or triggered when the candidate target PCell has better channel quality than the source PCell) by the wireless device indicating that the first RS of the candidate target PCell has higher channel quality (e.g., RSRP, RSRQ, SINR and/or RSSI, etc.) than a RS of the source PCell. The L1/2 CSI report for the candidate target PCell for a LTM procedure is different from a layer 1 (periodic, aperiodic, or semi-persistent) CSI report for a serving cell (e.g., a PCell, a SCell, or multiple TRPs of a serving cell) in existing technologies. The L1/2 CSI report for the candidate target PCell for a LTM procedure is different from a layer 3 filtered beam/cell report (e.g., RSRP/RSRQ/SINR) for a neighbor (or a non-serving) cell for layer 3 based handover in existing technologies. The L1/2 CSI report for a LTM procedure may comprise a value of the channel quality of the first RS of the candidate target PCell. The value of the channel quality may comprise a RSRP value, a RSRQ value, a RSSI value and/or a SINR value. The RSRP/RSRQ/RSSI/SINR value may be filtered by a layer 1 filter or a layer 3 filter. The L1/2 CSI report may be a UCI via a PUCCH/PUSCH, or a MAC CE via a PUSCH. The L1/2 CSI report is transmitted by the wireless device before the wireless device receives the PDCCH order. The wireless device may determine the pathloss based on a reference transmission power of the first RS and the reported RSRP value of the first RS in the L1/2 CSI report (e.g., pathloss is equal to the reference transmission power minus the reported RSRP value). Example embodiment may reduce power consumption for pathloss calculation.

In an example embodiment, the wireless device may transmit a plurality of L1/2 CSI reports in different time occasions before receiving the PDCCH order. Different L1/2 CSI reports may indicate different RSs and/or different candidate target PCells which have higher channel quality than the source PCell. The wireless device uses one or more RS, comprised in the most recent L1/2 CSI report from the plurality of L1/2 CSI reports before the wireless device receives the PDCCH order, to determine a pathloss reference for the uplink transmission power of the preamble triggered by the PDCCH order. The most recent L1/2 CSI report may be the L1/2 CSI report, of the plurality of L1/2 CSI reports, which is the last L1/2 CSI report transmitted by the wireless device before the wireless device receives the PDCCH order.

In an example embodiment, the wireless device may measure RSs of a candidate target PCell for L1/2 CSI report for the L1/2 triggered mobility (LTM) procedure. The RSs may be configured on multiple DL BWPs of a plurality of DL BWPs of the candidate target PCell. The wireless device, based on the PDCCH order triggering the transmission of the preamble via the candidate target PCell, may determine the RS of the candidate target PCell as a first RS of the plurality of RSs which is received via a first DL BWP of the plurality of DL BWPs of the candidate target PCell. The wireless device may determine the pathloss, for the preamble transmission via the candidate target PCell, based on a reference signal transmission power of the first RS of the first DL BWP and a measured RSRP of the first RS. The reference signal transmission power may be indicated in configuration parameters of the first DL BWP in one or more RRC messages of the candidate target PCell.

In an example embodiment, the wireless device determines the first DL BWP from the plurality of DL BWPs of the candidate target PCell, as a BWP indicated by firstActiveDLBWP-id of the candidate target PCell. The wireless device may determine the BWP indicated by firstActiveDLBWP-id of the candidate target PCell as a BWP to be used for pathloss measurement (for preamble transmission for ETA procedure) and as the BWP to be activated upon receiving a cell switch command indicating to switch from the source PCell to the candidate target PCell as the PCell or upon performing RRC reconfiguration (for layer 3 based handover).

In an example embodiment, the wireless device determines the first DL BWP from the plurality of DL BWPs of the candidate target PCell, as a BWP indicated by the PDCCH order. The PDCCH order may comprise a BWP indication indicating the first DL BWP of the candidate target PCell.

In an example embodiment, the wireless device determines the first DL BWP from the plurality of DL BWPs of the candidate target PCell, as a BWP indicated by initialDownlinkBWP of the candidate target PCell.

FIG. 42 shows an example embodiment of an ETA-based handover (or PCell switching, L1/2 triggered mobility, LTM, etc.) based on example of FIG. 41. In an example, a wireless device receives (at TO), and/or a base station/gNB (via a source PCell, Cell 0 in FIG. 42) transmits, one or more RRC messages comprising configuration parameters of Cell 1 as a candidate target PCell for the LTM procedure. The one or more RRC messages may further comprise configuration parameters of Cell 0 as the source PCell. The source PCell may be referred to as a (current) PCell before the wireless device performs the LTM procedure to switch the PCell to the target PCell in this specification. The one or more RRC messages may be implemented based on example embodiments described above with respect to FIG. 24A, FIG. 24B, FIG. 24C, FIG. 25, FIG. 26, FIG. 27, FIG. 33, FIG. 34 and/or FIG. 36. One or more examples of FIG. 24A, FIG. 24B, FIG. 24C, FIG. 25, FIG. 26, FIG. 27 may be used for configuring configuration parameters of Cell 0 as the source PCell. One or more example embodiment of FIG. 33, FIG. 34 and/or FIG. 36 may be used for configuring configuration parameters of Cell 1.

In an example, the base station configured with the source PCell may be referred to as a source base station/gNB. The source base station may communicate with a candidate target base station/gNB (configured with Cell 1) to coordinate whether Cell 1 is used as a candidate target PCell for the wireless device.

In an example, the one or more RRC message may configure a plurality of candidate target PCells including Cell 1. Each of the plurality of candidate target PCells may be associated with configuration parameters based on example embodiments described above.

In an example, a PCell is a cell in a cell group (e.g., MCG or SCG) for maintaining RRC connection between a base station and a wireless device. Each cell group may comprise one or more SCells.

In an example, a cell of the plurality of candidate target PCells including Cell 1 may be a neighbor or a non-serving cell of the wireless device, e.g., based on example embodiments described above with respect to FIG. 32. Cell 1 may not belong to a cell group (e.g., an MCG or a SCG) comprising Cell 0.

In an example, a cell of the plurality of candidate target PCells including Cell 1 may be a cell configured for ICBM associated with Cell 0 (e.g., as a part of Cell 0 when Cell 1 and Cell 0 belong to a same gNB-DU associated with a gNB-CU, or as a separate cell from Cell 0 when Cell 0 and Cell 1 belong to different gNB-DUs associated with a same gNB-CU or different gNB-CUs), e.g., based on example embodiments described above with respect to FIG. 31B, FIG. 37 and/or FIG. 38. A gNB-DU and/or a gNB-CU may be implemented based on example embodiments described above with respect to FIG. 1A and/or FIG. 1B.

In an example, a cell of the plurality of candidate target PCells including Cell 1 may be a serving cell (or a SCell) of the wireless device, e.g., based on example embodiments described above with respect to FIG. 39.

In an example, there may be at least one DL/UL BWP in an activated state on an activated SCell. When the SCell is deactivated, there is no active DL/UL BWP in activated state, e.g., based on example embodiments described above with respect to FIG. 22.

In an example, via the PCell (Cell 0) (not via a SCell of the cell group comprising the PCell), the base station may transmit NAS related information (e.g., mobility) and/or security related information to a wireless device. Via the PCell (Cell 0), the base station may maintain an RRC connection with the wireless device. Via the PCell (Cell 0), the wireless device performs an initial (RRC) connection establishment procedure or initiates a (RRC) connection re-establishment procedure.

In an example, Cell 0 may comprise a first plurality of (DL/UL) BWPs. Cell 1 may comprise a second plurality of (DL/UL) BWPs (e.g., DL BWP 1, DL BWP 2, DL BWP 3, UL BWP 1, UL BWP 2, UL BWP 3, etc. as shown in FIG. 42). In an example, there may be no DL/UL BWP in an active state on Cell 1, e.g., when Cell 1 is a non-serving cell before the wireless device switches from Cell 0 to Cell 1 as the PCell.

In an example, based on receiving the one or more RRC messages (e.g., at TO), the wireless device may communicate with the base station via Cell 0 and one or more SCells. Communicating with the base station may comprise receiving MIBs/SIBs/CSI-RSs/PDCCH/PDSCH and/or transmitting RACH/PUSCH/PUCCH/SRS.

In the example of FIG. 42, the wireless device, according to the received RRC messages comprising parameters of Cell 0 and/or Cell 1 (or a plurality of candidate target PCells), may perform layer 1/2 measurement report (e.g., L1/2 CSI report at T1) for the plurality of candidate target PCells and/or Cell 0. The layer 1/2 measurement report may comprise layer 1 RSRP, layer 1 RSRQ, PMI, RI, layer 1 SINR, CQI, etc.

In an example, the layer 1/2 measurement report for the LTM procedure may be event-triggered, e.g., when the measurement of the CSI/beam of a candidate target PCell (e.g., Cell 1) is greater than a threshold, or (amount of offset) greater than Cell 0, etc.

In an example, the layer 1/2 measurement report for the LTM procedure may be transmitted with a periodicity configured by the source base station.

In an example, the layer 1/2 measurement report for the LTM procedure may be contained in a UCI via PUCCH/PUSCH, or a MAC CE (e.g., event-triggered, associated with a configured SR for the transmission of the MAC CE).

In the example of FIG. 42, the wireless device may determine that Cell 1 has better channel quality than Cell 0. The wireless device may transmit, e.g., at T1, the layer 1/2 measurement report (L1 CSI report for Cell 1) indicating that Cell 1 has better channel quality than Cell 0. Upon receiving the layer 1/2 measurement report, the source base station and the candidate target base station may determine/coordinate whether Cell 1 is used as the target PCell for future cell switching.

In the example of FIG. 42, when determining Cell 1 is used as the target PCell for future HO/PCell switching (LTM procedure), the source base station (e.g., according to the request of the candidate target base station if there is no time alignment obtained yet for Cell 1), may transmit, at T2, from Cell 0 (or an activated SCell of the wireless device) a first command (1^st command) triggering an uplink transmission to (or via) Cell 1. The uplink transmission may be a transmission of a RA preamble or other uplink signals like SRS. The uplink transmission of a preamble/SRS is to allow the candidate target base station and/or the source base station to estimate in advance a TA for future uplink transmission via Cell 1. The first command may be a layer 1/2 command (e.g., a DCI/MAC CE) or an RRC message. In an example, the DCI may be based on a PDCCH order in existing technology.

In an example, the DCI may be a new PDCCH order different from the existing PDCCH order. The new PDCCH order may be with a DCI format 1_0 with an RNTI different from a C-RNTI used for the existing PDCCH order. The new PDCCH order may be with a DCI format comprising a field indicating that the DCI is the new PDCCH order different from the existing PDCCH order. The new PDCCH order may be received via a CORESET/search space different from a CORESET/search space used for a reception of the existing PDCCH order. The new PDCCH order may be received with a TCI state different from a TCI state from a TCI state used for a reception of the existing PDCCH order.

In an example, the new PDCCH order may be received with a TCI state associated with a PCI different from a PCI associated a TCI state used for a reception of the existing PDCCH order. The existing PDCCH order is received in a serving cell identified by a PCI.

In an example, the first command may comprise at least one of: an SSB index indicating a SSB of a plurality of SSBs of Cell 1, a RA preamble index, a PRACH mask index, a cell indication indicating Cell 1, an UL/SUL indicator, etc.

In the example of FIG. 42, the first command may comprise a second field indicating the second cell from a plurality of candidate target PCells for the ETA procedure.

In the example of FIG. 42, the wireless device, in response to receiving, via Cell 0, the first command triggering the uplink signal transmission via Cell 1, determines a pathloss reference (a pathloss RS and/or a downlink BWP of the BWPs of cell 1) for uplink transmission power determination for the uplink signal. Based on the pathloss reference, the wireless device may determine the uplink transmission power for the uplink signal.

In an example embodiment, the wireless device determines the pathloss reference as a SSB of SSBs of Cell 1 for the uplink transmission power determination for the uplink signal. The SSBs of Cell 1 may be indicated in the configuration parameters of Cell 1 comprised in the one or more RRC messages. Different from existing technologies where the wireless device uses a RS, of a serving cell where the wireless device receives a PDCCH order (or a RS QCLed with a DM-RS of the PDCCH order), as a pathloss reference for uplink transmission power calculation of a preamble triggered by the PDCCH order, example embodiment may enable the wireless device to determine a correct RS for the uplink transmission power calculation for the preamble. Using the SSB of the candidate target PCell, instead of a RS of the source PCell, to determine the pathloss may ensure the transmission of the preamble is correctly received by the candidate target PCell, e.g., when the candidate target PCell and the source PCell are not co-located and the preamble is triggered by a PDCCH order received via the source PCell.

In an example embodiment, one or more of the SSBs of the candidate target PCell may not overlap with the source PCell or a SCell in frequency domain, e.g., when the candidate target PCell and the source PCell are configured as intra-frequency deployment. The wireless device may not measure all the SSBs of the candidate target PCell due to limited measurement capability. The wireless device selects from the SSBs of the candidate target PCell, the SSB of the candidate target PCell (Cell 1) as the pathloss RS, based on the SSB overlapping with (on at least one RE/RB in frequency domain) an active DL BWP of Cell 0, an active DL BWP of a SCell (e.g., in active state or in deactivated state), and/or a configured DL BWP of Cell 0 or a SCell. The wireless device measure L1 CSI for the candidate target PCell over the SSB which is overlapping with the source PCell or the SCell (or an active/configured BWP of the source PCell or the SCell). The wireless device may not measure L1 CSI for the candidate target PCell over a second SSB which is not overlapping with the source PCell or the SCell (or the active/configured BWP of the source PCell or the SCell) for the intra-frequency measurement. Example embodiment, by using the SSB, of the candidate target PCell, overlapping with the source PCell or the SCell in frequency domain, may ensure that the wireless device obtains correct pathloss based on (RSRP) measurement of the SSB due to limited measurement capability for intra-frequency deployment. Example embodiments may reduce power consumption of the wireless device, and/or improve transmission reliability for the preamble via the candidate target PCell.

In an example embodiment, the wireless device may measure L1 CSI for the candidate target PCell over more than one SSB which are overlapping with a source PCell or an SCell (or an active/configured BWP of the source PCell or the SCell). The wireless device selects from the more than one SSB of the candidate target PCell, the SSB of the candidate target PCell (Cell 1) as the pathloss RS, based on the SSB having the lowest SSB index, the highest RSRP value and/or a RSRP value greater than a RSRP threshold (configured in the configuration parameters of Cell 1 in the one or more RRC message) among the more than one SSB overlapping with the source PCell or the SCell (or the active/configured BWP of the source PCell or the SCell). Example embodiments may reduce power consumption of the wireless device, and/or improve transmission reliability for the preamble via the candidate target PCell.

In an example embodiment, the SSB of the candidate target PCell (Cell 1) used as the pathloss RS may be indicated by the PDCCH order (or the first command received at T2). The PDCCH order may comprise an SSB index indicating the SSB of the plurality of SSBs of the candidate target PCell (Cell 1). The wireless device may further determine a PRACH occasion for the preamble transmission and/or a preamble based on the same SSB index. A PRACH occasion and/or a preamble being associated with an SSB index may be implemented based on example embodiments described above with respect to FIG. 34. Example embodiment, by indicating, in the PDCCH order, a SSB of the candidate target PCell as the reference for both a pathloss and a PRACH occasion/preamble, may reduce power consumption of the wireless device for the preamble transmission via the candidate target PCell.

In an example embodiment, the SSB of the candidate target PCell (Cell 1) used as the pathloss RS may be determined based on the L1/2 CSI report for Cell 1 (which is transmitted at T1 in FIG. 42), e.g., when the PDCCH order does not indicate the pathloss reference. The L1/2 CSI report for the LTM procedure in FIG. 42 may be transmitted (or triggered when the candidate target PCell has better channel quality than the source PCell) by the wireless device indicating that a first SSB of the candidate target PCell has higher channel quality (e.g., RSRP, RSRQ, SINR and/or RSSI, etc.) than a RS of the source PCell.

In the example of FIG. 42, the L1/2 CSI report for the candidate target PCell for a LTM procedure is different from a layer 1 (periodic, aperiodic, or semi-persistent) CSI report for a serving cell (e.g., a PCell, a SCell, or multiple TRPs of a serving cell) in existing technologies.

In the example of FIG. 42, the L1/2 CSI report for the candidate target PCell for the LTM procedure is different from a layer 3 filtered beam/cell report (e.g., RSRP/RSRQ/SINR) for a neighbor (or a non-serving) cell for layer 3 based handover in existing technologies.

In an example, the L1/2 CSI report for the LTM procedure may comprise a value of the channel quality of the first SSB of the candidate target PCell. The value of the channel quality may comprise a RSRP value, a RSRQ value, a RSSI value and/or a SINR value. The RSRP/RSRQ/RSSI/SINR value may be filtered by a layer 1 filter or a layer 3 filter. The L1/2 CSI report may be a UCI via a PUCCH/PUSCH, or a MAC CE via a PUSCH. The L1/2 CSI report is transmitted by the wireless device before the wireless device receives the PDCCH order.

In an example embodiment, the wireless device may determine the pathloss reference based on a reference transmission power (indicated by ss-PBCH-BlockPower IE for the candidate target PCell) of the first SSB and the reported RSRP value of the first SSB in the L1/2 CSI report (e.g., pathloss is equal to the reference transmission power minus the reported RSRP value). Example embodiment may reduce power consumption for pathloss calculation.

In an example embodiment, the L1/2 CSI report of the candidate target PCell for the LTM procedure may comprise more than one SSB of the candidate target PCell. The wireless device determines the pathloss based on the downlink transmission power of the first SSB selected, with the highest RSRP and/or the lowest SSB index, from the more than one SSB reported in the L1/2 CSI report.

In an example embodiment, the wireless device may transmit a plurality of L1/2 CSI reports for the LTM procedure in different time occasions starting T1 before receiving the PDCCH order at T2. Different L1/2 CSI reports may indicate different RSs and/or different candidate target PCells which have higher channel quality than the source PCell. The wireless device uses one or more SSB, comprised in the most recent L1/2 CSI report from the plurality of L1/2 CSI reports before the wireless device receives the PDCCH order, to determine a pathloss reference for the uplink transmission power of the preamble triggered by the PDCCH order. The most recent L1/2 CSI report may be the L1/2 CSI report, of the plurality of L1/2 CSI reports, which is the last L1/2 CSI report transmitted by the wireless device before the wireless device receives the PDCCH order. Using the most recent L1/2 CSI report (comprising the SSB and/or the RSRP value for the candidate target PCell) to determine a pathloss may allow the wireless device to determine an uplink transmission power based on the latest channel condition which may improve robustness of the uplink transmission and/or reduce power consumption of the wireless device.

In an example embodiment, when Cell 0 (source PCell) and Cell 1 (candidate target PCell) are configured as intra-frequency deployment (e.g., within a same frequency band), the wireless device determines the pathloss RS, for the preamble transmission for the ETA procedure, as a SSB, of Cell 1, overlapping with an active DL BWP of Cell 0 (or SCell(s) or a configured DL BWP of Cell 0 (or SCell(s).

In an example embodiment, when Cell 0 (source PCell) and Cell 1 (candidate target PCell) are configured as inter-frequency deployment (e.g., on different frequency bands), the wireless device determines the pathloss RS, for the preamble transmission for the ETA procedure, as an SSB, of Cell 1, indicated in a (or the most recent) L1/2 CSI report for Cell 1. The SSB is not overlapping with an active DL BWP of Cell 0 (or SCell(s) or a configured DL BWP of Cell 0 (or SCell(s).

In an example embodiment, the wireless device may measure RSs of a candidate target PCell for L1/2 CSI report for the L1/2 triggered mobility (LTM) procedure. The RSs may be configured on multiple DL BWPs of a plurality of DL BWPs of the candidate target PCell. Different DL BWPs may have different configuration parameters (transmission power, transmission periodicity, transmission ports etc.) for RSs. The wireless device, based on the PDCCH order triggering the transmission of the preamble via the candidate target PCell, may determine the RS of the candidate target PCell as a first RS of the plurality of RSs which is received via a first DL BWP of the plurality of DL BWPs of the candidate target PCell. The wireless device, based on the first DL BWP, determines a reference signal transmission power (ss-PBCH-BlockPower, powerControlOffsetSS, etc.) for the RSs. The wireless device uses the reference signal transmission power and a measured RSRP to determine a pathloss, as described above.

In an example embodiment, the wireless device determines the first DL BWP from the plurality of DL BWPs of the candidate target PCell, as a BWP indicated by firstActiveDLBWP-id of the candidate target PCell. The wireless device may determine the BWP indicated by firstActiveDLBWP-id of the candidate target PCell as a BWP to be used for pathloss measurement (for preamble transmission for ETA procedure) and as the BWP to be activated upon receiving a cell switch command indicating to switch from the source PCell to the candidate target PCell as the PCell or upon performing RRC reconfiguration (for layer 3 based handover). The wireless device may maintain the first BWP (or the BWP indicated by firstActiveDLBWP-id) of the candidate target PCell in deactivated state before receiving a cell switch command indicating to switch from the source PCell to the candidate target PCell as the PCell or before performing RRC reconfiguration (for layer 3 based handover). The wireless device may activate the first BWP (or the BWP indicated by firstActiveDLBWP-id) of the candidate target PCell upon receiving a cell switch command indicating to switch from the source PCell to the candidate target PCell as the PCell or upon performing RRC reconfiguration (for layer 3 based handover). Based on example embodiment, using the same DL BWP for the pathloss measurement before the cell switching (for preamble transmission) and after the cell switching (for PUCCH/PUSCH transmission) may improve power control accuracy and/or reduce power consumption of the wireless device for maintaining measurements for the LTM procedure.

In an example embodiment, the wireless device may select from the plurality of DL BWPs of the candidate target PCell, the first DL BWP (as the pathloss reference for the preamble transmission via the candidate target PCell triggered by the PDCCH order) overlapping with an active DL BWP of the source PCell (or an SCell), or a configured DL BWP of the source PCell (or the SCell), e.g., when the source PCell and the candidate target PCell are configured as intra-frequency deployment. Example embodiment, by using the DL BWP, of the candidate target PCell, overlapping with the source PCell or the SCell in frequency domain, may ensure that the wireless device obtains correct pathloss based on measurement of the SSBs on the DL BWP due to limited measurement capability for intra-frequency deployment. Example embodiments may reduce power consumption of the wireless device, and/or improve transmission reliability for the preamble via the candidate target PCell.

In an example embodiment, when Cell 0 (source PCell) and Cell 1 (candidate target PCell) are configured as intra-frequency deployment (e.g., within a same frequency band), the wireless device determines a DL BWP of the Cell 1 for the pathloss reference of the preamble transmission for the ETA procedure, as a BWP, of Cell 1, overlapping with an active DL BWP of Cell 0 (or SCell(s) or a configured DL BWP of Cell 0 (or SCell(s).

In an example embodiment, when Cell 0 (source PCell) and Cell 1 (candidate target PCell) are configured as inter-frequency deployment (e.g., on different frequency bands), the wireless device determines the pathloss reference, for the preamble transmission for the ETA procedure, as a BWP, of Cell 1, indicated as firstActiveDLBWP-id or initialDownlinkBWP. The BWP of Cell 1 is not overlapping with an active DL BWP of Cell 0 (or SCell(s) or a configured DL BWP of Cell 0 (or SCell(s).

In an example embodiment, the wireless device determines the first DL BWP from the plurality of DL BWPs of the candidate target PCell, as a BWP indicated by the PDCCH order. The PDCCH order may comprise a BWP indication indicating the first DL BWP of the candidate target PCell. Based on example embodiment, dynamically indicating a DL BWP for the pathloss measurement may improve power control accuracy.

In an example embodiment, the wireless device determines the first DL BWP from the plurality of DL BWPs of the candidate target PCell, as a BWP indicated by initialDownlinkBWP of the candidate target PCell.

In the example of FIG. 42, based on the determined pathloss reference (a DL BWP and/or an SSB) of Cell 1, the wireless device determines a transmission power for the preamble (or uplink signal in FIG. 42), P_PRACH,b,f(i), on an UL BWP b of carrier f of Cell 1 based on the pathloss RS in transmission occasion i as

$P_{\mathrm{PRACH},b,f}\left(i\right)=\min \left\{P_{\mathrm{CMAX},f}\left(i\right),P_{\mathrm{PRACH},\mathrm{target},f}+{\mathrm{PL}}_{b,f}\right\}\left[\mathrm{dBm}\right]$

where P_CMAX,f(i) is the wireless device configured maximum output power for carrier f of Cell 1 within transmission occasion i, P_{PRACH,target,f} is the PRACH target reception power PREAMBLE_RECEIVED_TARGET_POWER provided by higher layers (e.g., in 3GPP TS 38.321) for the UL BWP b of carrier f of Cell 1. When the uplink signal is an SRS, the above equation may be modified accordingly for the SRS transmission power determination.

In an example embodiment, PL_b,f is a pathloss for the UL BWP b of carrier f based on the SSB associated with the PRACH transmission on the DL BWP (based on example embodiments described above) of Cell 1 and calculated by the wireless device in dB as referenceSignalPower-L1/3 filtered RSRP in dBm.

In an example, the RSRP is measured by the wireless device (based on the SSB of Cell 1 as described above in T2) and/or reported in the L1/2 CSI report for Cell 1 (e.g., at T1 in FIG. 42).

In an example embodiment, the filter for the L1/3 filter RSRP may be configured by the base station in the configuration parameter of Cell 1 as a layer 3 filter with one or more layer 3 filter parameters, or as a layer 1 filter with one or more layer 1 filter parameters.

In an example embodiment, the wireless device determines a value of referenceSignalPower as indicated by ss-PBCH-BlockPower for the SSB of Cell 1 (or for the SSB of the determined DL BWP of Cell 1), wherein the SSB is determined (e.g., at T2 in FIG. 42) based on example embodiments described above.

In the example of FIG. 42, the wireless device may transmit, e.g., at T3, the uplink signal (preamble/SRS) with the determined transmission power via Cell 1. The target base station may monitor the uplink signal at T3 (based on coordination between the source base station and the target base station) to detect the uplink signal for TA estimation/acquisition. Based on the example embodiment for the uplink transmission power determination, the target base station may correctly receive the uplink signal at T3.

In the example of FIG. 42, the target base station may coordinate the indication of the estimated TA with the source base station.

In an example, the target base station may forward the estimated TA for Cell 1 to the source base station.

In an example, based on the first command, the wireless device may determine whether to monitor PDCCH (not shown in FIG. 42), via Cell 0 of the source base station, for receiving a RAR comprising the estimated TA for Cell 1 of the target base station.

In an example, in response to determining to monitor the PDCCH for receiving a response (e.g., the RAR), the wireless device may monitor the PDCCH for receiving the RAR corresponding to the preamble. The wireless device may monitor the PDCCH for the RAR based on existing technologies (e.g., based on examples of FIG. 13A, FIG. 13B and/or FIG. 13C). The source base station may transmit the forwarded TA to the wireless device via the RAR message.

In an example, in response to determining to skip monitoring the PDCCH for receiving the RAR, the wireless device may skip monitoring the PDCCH for receiving the RAR. The wireless device may skip the PDCCH monitoring or receiving the RAR.

In an example, the wireless device may communicate with the source base station (via Cell 0 and/or one or more activated SCells), e.g., comprising receiving downlink signals (PDCCH/PDSCH) after the wireless device transmits the preamble/SRS via Cell 1 and before receiving a second command indicating the PCell switching to Cell 1.

In the example of FIG. 42, the source base station transmits a second command (e.g., DCI/MAC CE), at T4, indicating a PCell switch/change from Cell 0 to Cell 1.

In an example, the base station may transmit the second command for L1/L2-triggered mobility, e.g., based on example embodiments described above with respect to FIG. 37.

In an example, the base station may transmit the second command for network energy saving, e.g., based on example embodiments described above with respect to FIG. 39. The second command may indicate a transition of the base station from a non-energy saving state (mode/period/configuration, or a full power state/mode, or a normal power state/mode) to an energy saving state. In an example, in the non-energy-saving state, the base station may transmit (and/or the wireless device may receive) MIBs/SSBs/CSI-RSs/TRSs/PDCCHs/PDSCHs via Cell 0 and may activate one or more SCells of a cell group for each wireless device. In the energy-saving state, the base station may transmit (and/or the wireless device may receive) MIBs/SSBs/CSI-RSs/PDCCHs/PDSCHs via a group common PCell (e.g., Cell 1) for all wireless devices and may deactivate (or turn off) other cells (e.g., SCells) for all wireless devices. In an example, the wireless device and/or the base station (or the source base station) may work in the non-energy-saving state between TO and T5. The wireless device and/or the base station (or the source base station) may work in the energy saving state starting from T5.

In an example, the second command may comprise at least one of: a cell indication indicating Cell 1, a TA indication indicating a TA value obtained based on the preamble/SRS transmission via Cell 1, a TCI state indication indicating a beam to be used for Tx/Rx on Cell 1, a RACH procedure enabling/disabling indication, etc.

In the example of FIG. 42, in response to receiving the second command indicating the PCell change/switch to Cell 1 at T4, the wireless device may apply the TA value (obtained at T4 based on the second command) for uplink transmission (at T5) via Cell 1. The uplink transmission may comprise PUSCH, PUCCH and/or SRS.

In an example, in response to receiving the second command, the wireless device may configure Cell 1 as the PCell and/or may stop using Cell 0 as the PCell. In response to receiving the second command, the wireless device may stop applying RRC configuration parameters of Cell 0 and/or may apply RRC configuration parameters of Cell 1. In response to receiving the second command, the wireless device may stop receiving RRC messages from Cell 0 and/or may start receiving RRC messages from Cell 1.

Based on one or more example embodiments of FIG. 42, a wireless device may correctly determine a pathloss reference (SSB and/or DL BWP of a candidate target PCell) for a preamble/SRS transmission via the candidate target PCell (e.g., where the preamble/SRS transmission is triggered by a DCI received via a source PCell) before the wireless device switches from the source PCell to the candidate target PCell as the PCell upon receiving a cell switch command. The candidate target PCell may be a non-serving cell before the wireless device conducts the cell switching. The candidate target PCell may be intra-frequency deployed with the source PCell. The candidate target PCell may be inter-frequency deployed with the source PCell. Example embodiment may reduce power consumption for pathloss calculation and/or improve transmission robustness for the preamble/SRS transmission via the candidate target PCell.

In existing technologies, a wireless device may determine a power priority order to adjust transmission power of a plurality of uplink signals when the plurality of uplink signals via one or more serving cell (e.g., a PCell and/or a SCell) overlap in time domain (e.g., on at least one OFDM symbol) and if a total (required) transmission power for the plurality of uplink signals exceeds an allowed maximum transmission power (PCMAX (i) which is a linear value of PCMAX (i) in transmission occasion i based on the wireless device power class and a frequency range).

In existing technologies, the power priority order (from highest to lowest) of the plurality of uplink signals (PRACH, PUCCH, PUSCH, SRS) are specified as: PRACH transmission via a PCell, PUCCH/PUSCH with larger priority index, PUCCH/PUSCH with lower priority index, SRS or PRACH via a serving cell other than the PCell. In case of same priority order and for operation with carrier aggregation, the wireless device prioritizes power allocation for transmissions on the PCell of the MCG or the SCG over transmissions on an SCell. In case of same priority order and for operation with two UL carriers, the wireless device prioritizes power allocation for transmissions on the carrier where the wireless device is configured to transmit PUCCH. If PUCCH is not configured for any of the two UL carriers, the wireless device prioritizes power allocation for transmissions on the non-supplementary UL carrier.

In an example, when a LTM procedure is configured, the wireless device may transmit a first uplink signal (e.g., a preamble or SRS) via a candidate target PCell, triggered by a DCI (or a PDCCH order), for an ETA procedure associated with a LTM procedure based on example embodiments described above with respect to FIG. 41 and/or FIG. 42. Different from existing technologies, the candidate target PCell may be a non-serving cell. Based on existing technologies, the wireless device may have difficulty in determining a power priority order of the first uplink signal for the non-serving cell (or the candidate target PCell) and second uplink signal(s) (e.g., PUCCH/PUSCH/SRS/PRACH) via one or more serving cell (e.g., PCell and/or SCell) when the first uplink signal for the non-serving cell and the second uplink signal(s) for the serving cell(s) overlap in time domain and a total transmission power of the first uplink signal and the second uplink signal(s) exceeds an allowed maximum transmission power of the wireless device. The wireless device, by implementing existing technologies, may adjust the transmission power of the first uplink signal incorrectly which may reduce reliability of the transmission to the candidate target PCell. There is a need to improve reliability of the transmission to the candidate target PCell.

In an example embodiment, the wireless device may determine a first transmission power of a first uplink signal via a candidate target cell (e.g., a non-serving cell), e.g., based on example embodiments described above with respect to FIG. 42. The wireless device may determine a second transmission power of second uplink signal(s) via one or more serving cell (e.g., a source PCell and/or a SCell), e.g., based on existing technologies. The wireless device may determine that a first transmission occasion of the first uplink signal overlaps with a second transmission occasion of the second uplink signal(s) in time domain (e.g., on at least one OFDM symbol). The wireless device may determine a total transmission power which is a sum of the first transmission power and the second transmission power. In response to the total transmission power in a time interval (e.g., a symbol/slot) exceeding an allowed maximum transmission power of the wireless device, the wireless device may determine a (power allocation) priority order for the first uplink signal and the second uplink signal(s) based on at least one of: an uplink signal type and/or a cell type (e.g., a serving cell or a non-serving cell, a PCell or a SCell).

In an example embodiment, the wireless device determines the power priority of the first uplink signal via the candidate target cell is same as that of the second uplink signal(s) via the PCell when the candidate target cell is configured as a candidate target PCell as a non-serving cell, the first uplink signal is a first PRACH and the second uplink signal(s) is a second PRACH. Example embodiments may enable the wireless device to ensure enough transmission power allocated to the PRACH transmitted via the candidate target PCell.

In an example embodiment, the wireless device determines the power priority of the first uplink signal is lower than a power priority of a PRACH via the PCell and/or higher than a power priority of a PUCCH/PUSCH via the PCell, e.g., when the first uplink signal is a PRACH.

In an example embodiment, the wireless device determines the power priority of the first uplink signal is same as a power priority of a PRACH via an activated SCell, e.g., when the candidate target cell is configured as a candidate target PCell (or SCell) and the first uplink signal is a PRACH.

In an example embodiment, the wireless device determines the power priority of the first uplink signal is lower than a power priority of a PRACH via an activated SCell, e.g., when the candidate target cell is configured as a candidate target PCell (or SCell) and the first uplink signal is a PRACH.

In an example embodiment, the wireless device determines the power priority of the first uplink signal is same as (or lower than) a power priority of an SRS via the PCell, e.g., when the candidate target cell is configured as a candidate target PCell as a non-serving cell, the first uplink signal is an SRS.

In an example embodiment, the wireless device determines the power priority of the first uplink signal is same as (or lower than) a power priority of an SRS via an activated SCell, e.g., when the first uplink signal is an SRS.

FIG. 43 shows an example of uplink power determination for an uplink signal transmission via a candidate target PCell (a non-serving cell) when the uplink signal transmission overlaps with an uplink signal transmission via a serving cell (e.g., a PCell and/or a SCell) based on example embodiments described above with respect to FIG. 42.

In an example, a wireless device may determine a first uplink transmission power for a first uplink signal transmitted via a first cell (e.g., a source PCell, or an activated SCell). The wireless device may determine the first uplink transmission power for the first uplink signal, e.g., based on existing technologies (e.g., as specified by TS 38.213 V17.3.0 section 7). The first uplink signal may be a PRACH/PUCCH/PUSCH/SRS.

In an example, the wireless device may determine a second uplink transmission power for a second uplink signal transmitted via a second cell (e.g., a candidate target cell (PCell/SCell), a non-serving cell), e.g., based on example embodiments described above with respect to FIG. 42. The second uplink signal may be a RA preamble or an SRS. The second uplink signal may be triggered by receiving from the source base station a DCI, a MAC CE and/or an RRC message. The second uplink signal may be trigged by the wireless device based on one or more measurement events (e.g., a RSRP value of the source PCell being lower than a RSRP value of a candidate target cell, a TA associated with the candidate target cell expiring, etc.).

In the example of FIG. 43, the wireless device may determine that the first uplink signal overlaps the second uplink signal in time domain on at least one OFDM symbol. The wireless device may determine a total transmission power (a sum of the first uplink transmission power and the second uplink transmission power) exceeds an allowed transmission power value (e.g., configured by the base station in one or more RRC message).

In the example of FIG. 43, the wireless device, based on the first uplink signal overlapping the second uplink signal in time domain on at least one OFDM symbol and the total transmission power exceeding an allowed transmission power value, may adjust/allocate the first transmission power and/or the second transmission power based on a transmission power priority order of the first uplink signal and the second uplink signal.

In an example embodiment, the second uplink signal may be a PRACH (a RA preamble). The first uplink signal may be a PRACH/PUCCH/PUSCH/SRS. The transmission power priority order may be determined (from highest priority to lowest priority) as: PRACH via the source PCell, PRACH via the candidate target cell (with a same priority of the PRACH via the source PCell or lower than that of the PRACH via the source PCell), PUCCH/PUSCH via the source PCell, SRS and/or PRACH via a serving cell other than the source PCell and/or via the candidate target cell.

In an example embodiment, the second uplink signal may be a PRACH (a RA preamble). The first uplink signal may be a PRACH/PUCCH/PUSCH/SRS. The transmission power priority order may be determined (from highest priority to lowest priority) as: PRACH via the candidate target cell, PRACH via the source PCell, PUCCH/PUSCH via the source PCell, SRS and/or PRACH via a serving cell other than the source PCell and/or via the candidate target cell.

In an example embodiment, the second uplink signal may be a PRACH (a RA preamble). The first uplink signal may be a PRACH/PUCCH/PUSCH/SRS. The transmission power priority order may be determined (from highest priority to lowest priority) as: PRACH via the source PCell, PUCCH/PUSCH via the source PCell, SRS and/or PRACH via a serving cell other than the source PCell, PRACH via the candidate target cell (with a same priority of the PRACH via the serving cell other than the source PCell or lower than that of the PRACH via the serving cell other than the source PCell).

In an example embodiment, the second uplink signal may be a PRACH (a RA preamble). The first uplink signal may be a PRACH/PUCCH/PUSCH/SRS. The transmission power priority order may be determined (from highest priority to lowest priority) as: PRACH via the source PCell, PUCCH/PUSCH via the source PCell, PRACH via the candidate target cell, SRS and/or PRACH via a serving cell other than the source PCell and/or via the candidate target cell.

In an example embodiment, the second uplink signal may be an SRS. The first uplink signal may be a PRACH/PUCCH/PUSCH/SRS. The transmission power priority order may be determined (from highest priority to lowest priority) as: PRACH via the source PCell, PUCCH/PUSCH via the source PCell, SRS and/or PRACH via a serving cell other than the source PCell, SRS via the candidate target cell (with a same priority of the SRS via the serving cell or lower than that of the SRS via the serving cell).

In an example embodiment, the second uplink signal may be an SRS. The first uplink signal may be a PRACH/PUCCH/PUSCH/SRS. The transmission power priority order may be determined (from highest priority to lowest priority) as: PRACH via the source PCell, PUCCH/PUSCH via the source PCell, SRS via the candidate target cell, SRS and/or PRACH via a serving cell other than the source PCell and/or via the candidate target cell.

In an example, based on the power priority order, of the first uplink signal and the second uplink signal, indicating that the second uplink signal has higher priority, the wireless device may allocate a first transmission power for the second uplink signal which does not exceed the allowed maximum transmission power (e.g., based on example embodiments described above with respect to FIG. 42) and then allocate a second transmission power for the first uplink signal which does not exceed a remaining transmission power which is the allowed maximum transmission power minus the first transmission power for the second uplink signal.

In an example, based on the power priority order, of the first uplink signal and the second uplink signal, indicating that the first uplink signal has higher priority, the wireless device may allocate a first transmission power for the first uplink signal which does not exceed the allowed maximum transmission power and then allocate a second transmission power for the second uplink signal which does not exceed the remaining transmission power which is the allowed maximum transmission power minus the first transmission power for the first uplink signal.

Based on example embodiments of FIG. 43, the wireless device, by allocating a transmission power for the uplink transmission via a candidate target cell based on a determined priority order when a transmission power of the wireless device is limited based on a power class of the wireless device, may improve reliability of the transmission to a candidate target cell and/or the transmission to a source PCell or a SCell.

In an example embodiment, a wireless device receives from a base station via a first cell as a PCell, a DCI indicating a transmission of a RA preamble via a second cell. The wireless device determines a pathloss, for the transmission of the RA preamble via the second cell, based on a first SSB of SSBs of the second cell. The wireless device transmits the preamble via the second cell and with an uplink transmission power determined based on the pathloss. The wireless device receives, via a third cell, a MAC CE (or a second DCI) indicating to switch from the first cell to the second cell as the PCell. The wireless device switches to the second cell as the PCell. The third cell may be same as the first cell. The third cell may be a SCell different from the first cell.

In an example embodiment, a wireless device receives from a base station via a first cell as a PCell, a PDCCH order (in a DCI) indicating a transmission of a RA preamble via a second cell comprising (downlink) BWPs. The wireless device determines a pathloss, for the transmission of the RA preamble via the second cell, based on a first SSB of SSBs of a first BWP of the BWPs of the second cell. The wireless device transmits the preamble via the second cell and with an uplink transmission power determined based on a target received power of the preamble and the determined pathloss. The wireless device receives a MAC CE (or a second DCI) indicating to switch from the first cell to the second cell as the PCell. The wireless device switches to the second cell as the PCell comprising activating the first BWP of the BWPs.

According to an example embodiment, the third cell is same as the first cell.

According to an example embodiment, the third cell is an activated SCell different from the first cell.

According to an example embodiment, the first cell comprises a plurality of BWPs. The wireless device receives the DCI, via a PDCCH of a second BWP of the plurality of BWPs of the first cell, indicating the PDCCH order.

According to an example embodiment, the second BWP of the first cell is different from the first BWP of the second cell.

According to an example embodiment, the second BWP of the first cell and the first BWP of the second cell are in different frequency bands.

According to an example embodiment, the first BWP is selected from the BWPs of the second cell based on at least one of: the first BWP overlapping with the second (or configured) BWP of the first cell on at least one RE/RB in frequency domain and the first BWP overlapping with an activated (or configured) BWP of an activated SCell, on at least one RE/RB in frequency domain.

According to an example embodiment, the wireless device receives the DCI via the second BWP based on the second BWP being in activated state.

According to an example embodiment, the wireless device deactivates the second BWP of the first cell in response to switching to the second cell as the PCell.

According to an example embodiment, the wireless device maintains the first BWP of the second cell a deactivated state before receiving the MAC CE (or a second DCI) indicating to switch from the first cell to the second cell as the PCell.

According to an example embodiment, the first BWP is same as a BWP of the BWPs of the second cell, wherein the BWP is configured as a first active BWP which is to be activated upon performing radio resource control (RRC) configuration or reconfiguration. The configuration parameters of the second cell comprise a BWP identifier identifying the first active BWP.

According to an example embodiment, the first BWP is same as a BWP of the BWPs of the second cell, wherein the BWP is configured to be activated upon receiving the MAC CE (or a second DCI) indicating to switch to the second cell as the PCell.

According to an example embodiment, the BWP is same as a first active BWP configured to be activated upon performing RRC configuration or reconfiguration.

According to an example embodiment, the BWP is different from a first active BWP configured to be activated upon performing RRC configuration or reconfiguration.

According to an example embodiment, the configuration parameters of the second cell comprise a BWP identifier identifying the BWP configured to be activated upon receiving the MAC CE (or a second DCI) indicating to switch to the second cell as the PCell.

According to an example embodiment, the first BWP is configured as a BWP of the BWPs of the second cell and dedicated for a pathloss measurement for the preamble transmission for the second cell before receiving the MAC CE (or a second DCI) indicating to switch to the second cell as the PCell.

According to an example embodiment, the first BWP is different from at least one of: a second BWP configured to be activated upon performing RRC configuration or reconfiguration and a third BWP configured to be activated upon receiving the MAC CE (or a second DCI) indicating to switch to the second cell as the PCell.

According to an example embodiment, the wireless device maintains the first BWP deactivated during the transmission of the preamble.

According to an example embodiment, the wireless device maintains an active BWP, of the first cell, in the active state during the transmission of the preamble to the second cell.

According to an example embodiment, the first BWP is indicated in the PDCCH order. The PDCCH order comprises a cell indication indicating the second cell. The PDCCH order comprises a BWP index indicating the first BWP.

According to an example embodiment, the PDCCH order comprises a SSB index indicating a SSB of a plurality of SSBs of the second cell, associated with a PRACH occasion (for the preamble transmission) of a plurality of PRACH occasions, each SSB being associated with one or more PRACH occasions of the plurality of PRACH occasions.

According to an example embodiment, the first SSB is same as the SSB indicated by the SSB index comprised in the PDCCH order.

According to an example embodiment, the configuration parameters of the second cell comprise configuration parameters of the SSBs of the second cell, each SSB of the SSBs being associated with a respective preamble of a plurality of preambles. Each preamble is identified by a preamble index.

According to an example embodiment, the SSBs are received via the first BWP of the BWPs of the second cell, wherein the first BWP is deactivated based on at least one of: the second cell not being a serving cell and the second cell being a deactivated secondary cell.

According to an example embodiment, the first cell is a serving cell before switching the PCell to the second cell.

According to an example embodiment, the second cell is a non-serving cell before switching the PCell to the second cell.

According to an example embodiment, the second cell is a deactivated SCell before switching the PCell to the second cell.

According to an example embodiment, the first cell is a non-serving cell after switching the PCell to the second cell.

According to an example embodiment, the second cell is a serving cell after switching the PCell to the second cell.

According to an example embodiment, the first cell is a deactivated SCell after switching the PCell to the second cell.

According to an example embodiment, the wireless device receives the DCI indicating the PDCCH order. The wireless device determines the DCI indicating the PDCCH order based on at least one of: a C-RNTI identifying the wireless device and a FDRA field of the DCI being set to all ones. The DCI comprises an indication indicating whether an UL carrier or a SUL carrier of the second cell is used for the preamble transmission.

According to an example embodiment, the wireless device receives RRC messages comprising configuration parameters of the second cell. The configuration parameters of the second cell comprise the target received power of the preamble. The configuration parameters of the second cell comprise a downlink transmission power of the first SSB

According to an example embodiment, the wireless device transmits a CSI report for the second cell before receiving the PDCCH order, wherein the CSI report comprises: an SSB index indicating the first SSB and an RSRP value of the first SSB.

According to an example embodiment, the RSRP value is a layer 1 RSRP value filtered with a layer 1 filter configured in the configuration parameters of the second cell. The layer 1 filter may be configured with one or more layer 1 filter parameters differently and separately configured from one or more layer 3 filter parameters for layer 3 RSRP value for layer 3 beam/cell measurement reports.

According to an example embodiment, the RSRP value is a layer 3 RSRP value filtered with a layer 3 filter configured in the configuration parameters of the second cell.

According to an example embodiment, the wireless device transmits the CSI report for the second cell in response to the RSRP value of the first SSB of the second cell being higher than a RSRP value of the first cell. The CSI report is transmitted in at least one of: an UCI and/or a MAC CE. The wireless device determines the pathloss based on the downlink transmission power of the first SSB and the RSRP value of the first SSB.

According to an example embodiment, the wireless device the pathloss based on the downlink transmission power of the first SSB selected, with the highest RSRP and/or the lowest SSB index, from one or more SSBs reported in the CSI report, when the CSI report comprises the one or more SSBs.

According to an example embodiment, the wireless device determines the pathloss based on the CSI report which is the most recent CSI report of a plurality of CSI reports transmitted before receiving the PDCCH order, wherein each CSI report of the plurality of CSI reports is transmitted in a respective uplink transmission occasion of a plurality of uplink transmission occasions.

According to an example embodiment, the wireless device selects the first SSB from the SSBs of the second cell base on at least one of: the first SSB overlapping with an active BWP of the first cell in frequency domain (on at least one RE/RB), the first SSB overlapping with an active BWP of an activated SCell in frequency domain (on at least one RE/RB).

According to an example embodiment, the wireless device selects the first SSB from one or more SSBs, of the SSBs of the second cell, overlapping with an active BWP of the first Cell or an activated SCell, based on at least one of: the first SSB with the lowest SSB index, the first SSB with the highest RSRP and/or the first SSB with a RSRP value greater than a RSRP threshold (e.g., configured in the configuration parameters of the second cell).

According to an example embodiment, the wireless device determines, in response to a first transmission occasion for the preamble overlapping with a second transmission occasion of a second uplink signal, a power priority order of the preamble and the second uplink signal. The wireless device allocates a first power to the preamble and a second power to the second uplink signal based on the determined power priority order, wherein a total transmit power comprising the first power and the second power is smaller than or equal to a configured maximum power value. The wireless device transmits the preamble via the second cell with the first power.

In an example embodiment, a wireless device receives via a first cell a DCI indicating a transmission of a preamble via a second cell. The wireless device determines, in response to a first transmission occasion for the preamble overlapping with a second transmission occasion of a second uplink signal, a power priority order of the preamble and the second uplink signal. The wireless device allocates a first power to the preamble and a second power to the second uplink signal based on the determined power priority order, wherein a total transmit power comprising the first power and the second power is smaller than or equal to a configured maximum power value. The wireless device transmits the preamble via the second cell with the first power.

According to an example embodiment, the second uplink signal comprises at least one of: a PRACH via the first cell, a PUCCH/PUSCH via the first cell, an SRS via the first cell and/or a PRACH via an activated SCell.

According to an example embodiment, the PRACH via the first cell, as a PCell, is triggered by a PDCCH order received via the first cell, a beam failure recovery procedure on the first cell and/or an initial RA procedure.

According to an example embodiment, the PRACH via the activated SCell is triggered by a PDCCH order received via the activated SCell.

According to an example embodiment, the second cell does not belong to an MCG or a SCG.

According to an example embodiment, the wireless device determines the power priority of the preamble is same as a second power priority of a PRACH via the first cell.

According to an example embodiment, the wireless device determines the power priority of the preamble is lower than a second power priority of a PRACH via the first cell and higher than a third power priority value of a PUCCH/PUSCH via the first cell.

According to an example embodiment, the wireless device determines the power priority of the preamble is same as a second power priority of a PRACH via the activated SCell.

According to an example embodiment, the wireless device determines the power priority of the preamble is lower than a second power priority of a PRACH via the activated SCell.

Clause 1. A method comprising: receiving, by a wireless device via a serving cell, a physical downlink control channel (PDCCH) order comprising: a cell indicator indicating a candidate cell for a layer 1/2 triggered mobility (LTM) procedure; a synchronization signal block (SSB) index indicating a SSB of the candidate cell; and a preamble index of a preamble; and transmitting, via a physical random access channel (PRACH) occasion corresponding to the SSB of the candidate cell, the preamble using an uplink transmission power based on a measurement of a pathloss of the SSB.

Clause 2. A method comprising: receiving, by a wireless device via a serving cell, a physical downlink control channel (PDCCH) order triggering a physical random access channel (PRACH) transmission via a candidate cell for a layer 1/2 triggered mobility (LTM) procedure, wherein the PDCCH order comprise: a synchronization signal block (SSB) index indicating a SSB of the candidate cell; and a preamble index of a preamble for the PRACH transmission; and transmitting, via a PRACH occasion corresponding to the SSB of the candidate cell, the preamble using an uplink transmission power based on a measurement of a pathloss of the SSB of the candidate cell.

Clause 3. The method of clause 2, further comprising measuring the pathloss based on: a transmission power of the SSB; and a reference signal received power (RSRP) of the SSB.

Clause 4. The method of clause 3, wherein the transmission power of the SSB is configured in configuration parameters of the candidate cell.

Clause 5. The method of clause 4, wherein the configuration parameters of the candidate cell comprise configuration parameters of a plurality of SSBs, comprising the SSB, transmitted via the candidate cell.

Clause 6. The method of clause 5, wherein the SSB index of the PDCCH order indicates the SSB of the plurality of SSBs of the candidate cell.

Clause 7. The method of any of clauses 4 to 6, further comprising receiving one or more radio resource control (RRC) messages comprising the configuration parameters of the candidate cell for the LTM procedure.

Clause 8. The method of clause 7, wherein the wireless device receives the one or more RRC messages via at least one of a plurality of serving cells configured for the wireless device, wherein the plurality of serving cells comprise the serving cell.

Clause 9. The method of clause 8, wherein the plurality of serving cells comprise: a first serving cell as a primary cell (PCell); and zero or non-zero number of secondary cells (SCells).

Clause 10. The method of clause 9, wherein the serving cell is the PCell of the plurality of serving cells.

Clause 11. The method of clause 9, wherein the serving cell is a secondary cell (SCell) of the plurality of serving cells.

Clause 12. The method of any of clauses 9 to 11, further comprising: receiving, via at least one of the plurality of serving cells, a medium access control control element (MAC CE) indicating to switch from the first serving cell to the candidate cell as the PCell for the LTM procedure; switching from the first serving cell to the candidate cell as the PCell; and receiving, in response to switching to the candidate cell as the PCell, downlink signals via an initial downlink bandwidth part (BWP) of the candidate cell.

Clause 13. The method of clause 12, wherein the wireless device receives the downlink signals via the initial downlink BWP of the candidate cell, in response to activating the initial downlink BWP of the candidate cell in response to switching from the first serving cell to the candidate cell as the PCell triggered by receiving the MAC CE.

Clause 14. The method of clause 13, wherein the configuration parameters of the candidate cell indicate a plurality of downlink BWPs configured on the candidate cell, wherein: each of the plurality of downlink BWPs is associated with a BWP index and one or more BWP specific parameters; and the plurality of downlink BWPs comprise an initial active downlink BWP.

Clause 15. The method of clause 14, wherein the wireless device maintains the initial downlink BWP of the candidate cell in a deactivated state before receiving the MAC CE indicating to switch from the first serving cell to the candidate cell as the PCell.

Clause 16. The method of clause 14 or clause 15, further comprising maintaining the initial downlink BWP of the candidate cell in a deactivated state during the transmission of the preamble.

Clause 17. The method of any one of clauses 12 to 16, wherein the MAC CE comprises at least one of: a timing advance command (TAC) indicating a timing advance (TA) value for the candidate cell; a cell indicator indicating the candidate cell; a transmission configuration indication (TCI) state; and one or more field indicating whether a random access channel (RACH) procedure is triggered when the wireless device switches from the first serving cell to the candidate cell as the PCell.

Clause 18. The method of clause 17, wherein the PDCCH order triggers an early timing advance acquisition for the candidate cell for the LTM procedure, wherein the TA value indicated in the MAC CE is associated with the early timing advance acquisition for the candidate cell.

Clause 19. The method of clause 17 or clause 18, wherein the wireless device receives the downlink signals based on the TCI state indicated by the MAC CE.

Clause 20. The method of any of clauses 17 to 19, further comprising transmitting uplink signals via an initial uplink BWP of the candidate cell, with an uplink transmission timing based on the TA value indicated by the MAC CE, wherein the uplink signals comprise at least one of: a physical uplink shared channel (PUSCH); a physical uplink control channel (PUCCH); and a sounding reference signal (SRS).

Clause 21. The method of any one of clauses 17 to 20, further comprising transmitting a second preamble via the candidate cell in response to the one or more field, of the MAC CE, indicating that the RACH procedure is triggered when the wireless device switches from the first serving cell to the candidate cell as the PCell, based on receiving the MAC CE.

Clause 22. The method of clause 21, wherein the RACH procedure, triggered by the MAC CE, is different from a RACH procedure triggered by the PDCCH order.

Clause 23. The method of clause 21 or clause 22, wherein the RACH procedure is a contention-free RACH procedure.

Clause 24. The method of any one of clauses 1 to 23, wherein the PDCCH order comprises a cell indicator indicating the candidate cell.

Clause 25. The method of clause 24, wherein the cell indicator of the PDCCH order indicates the candidate cell from a plurality of candidate cells configured for the LTM procedure.

Clause 26. The method of clause 25, further comprising receiving one or more RRC messages comprising configuration parameters of the plurality of candidate cells for the LTM procedure.

Clause 27. The method of any one of clauses 1 to 26, wherein the candidate cell is a non-serving cell different from the serving cell.

Clause 28. The method of any one of clauses 1 to 27, wherein the SSB is received via an initial downlink BWP of downlink BWPs of the candidate cell, wherein the initial downlink BWP is in a deactivated state based on at least one of: the candidate cell being a non-serving cell; and the candidate cell being a deactivated secondary cell.

Clause 29. The method of any one of clauses 1 to 28, wherein the wireless device selects the PRACH occasion, from a plurality of RACH occasions configured on the candidate cell, corresponding to the SSB.

Clause 30. The method of clause 29, further comprising receiving one or more RRC messages comprising configuration parameters of the candidate cell for the LTM procedure, wherein the configuration parameters indicate: a first number of SSBs comprising the SSB; a second number of PRACH occasions, comprising the PRACH occasion, wherein: each PRACH occasion of the second number of PRACH occasions corresponds to a respective number of SSBs of the first number of SSBs; or each SSB of the first number of SSBs corresponds to a respective number of PRACH occasions of the second number of PRACH occasions; and a transmission power of each of the first number of SSBs.

Clause 31. The method of any one of clauses 1 to 30, wherein the PRACH occasion is associated with a number of symbols in time domain and a number of resource blocks (RBs) in frequency domain.

Clause 32. The method of any one of clauses 1 to 31, further comprising in response to transmitting the preamble for a random access channel (RACH) procedure, completing a RACH procedure, for the PRACH transmission, triggered by the PDCCH order.

Clause 33. The method of clause 32, wherein the completing the RACH procedure comprise at least one of: skipping starting a random access response (RAR) window after transmitting the preamble; and skipping monitoring a PDCCH via the serving cell or the candidate cell for receiving a RAR corresponding to the preamble.

Clause 34. The method of any one of clauses 1 to 33, further comprising: determining, in response to the PRACH occasion for the preamble, on the candidate cell, overlapping in time with a transmission of an uplink signal on at least one of a plurality of serving cells, to prioritize power allocation to the transmission of the preamble to the candidate cell over the transmission of the uplink signal on the at least one of the plurality of serving cells; and allocating, based on the determining, the uplink transmission power to the preamble and a second uplink transmission power to the uplink signal so that a total transmission power comprising the uplink transmission power and the second uplink transmission power is smaller than or equal to a configured maximum power value.

Clause 35. The method of clause 34, further comprising transmitting the uplink signal on the at least one of the plurality of serving cells with the second uplink transmission power.

Clause 36. The method of clause 34 or clause 35, wherein the at least one of the plurality of serving cells comprise a PCell.

Clause 37. The method of any one of clauses 34 to 36, wherein the uplink signal comprises a second preamble via a PCell comprised in the plurality of serving cells.

Clause 38. The method of any one of clauses 34 to 37, wherein the uplink signal is a second preamble triggered by at least one of: a second PDCCH order received via a primary cell (PCell); a beam failure recovery procedure on the PCell; and an initial random access (RA) procedure.

Clause 39. The method of any one of clauses 34 to 38, wherein the wireless device determines the second uplink transmission power, for the uplink signal on the at least one of the plurality of serving cells, based on a pathloss measurement of a pathloss reference signal of the at least one of the plurality of serving cells.

Clause 40. The method of any one of clauses 1 to 39, wherein the wireless device receives a downlink control information (DCI), via a PDCCH of an active BWP of a plurality of BWPs of the serving cell, indicating the PDCCH order.

Clause 41. The method of clause 40, wherein the DCI is transmitted with a DCI format 1_0.

Clause 42. The method of clause 41, wherein the DCI indicates the PDCCH order in response to at least one of: cyclic redundancy check (CRC) bits of the DCI being scrambled by a cell radio network temporary identifier (C-RNTI) of the wireless device; and/or frequency domain resource assignment field being set to all ones.

Clause 43. The method of any one of clauses 1 to 42, further comprising receiving one or more RRC messages comprising configuration parameters of a plurality of serving cells comprising the serving cell.

Clause 44. The method of clause 43, further comprising releasing the configuration parameters of the plurality of serving cells in response to switching from the serving cell to the candidate cell as a primary cell (PCell) triggered by receiving the MAC CE.

Clause 45. The method of clause 43 or clause 44, further comprising determining the plurality of serving cells as non-serving cells in response to switching from the serving cell to the candidate cell as a primary cell (PCell).

Clause 46. The method of any one of clauses 1 to 45, wherein the switching from the serving cell to the candidate cell comprises at least one of: resetting a MAC entity of the wireless device; stopping receiving PDCCHs/PDSCHs from the serving cell and transmitting PUSCHs/PUCCHs via the serving cell; and starting to receive PDCCHs/PDSCHs from the candidate cell and transmit PUSCHs/PUCCHs via the candidate cell.

Clause 47. A method comprising: transmitting, by a base station via a serving cell to a wireless device, a physical downlink control channel (PDCCH) order comprising: a cell indicator indicating a candidate cell for a layer 1/2 triggered mobility (LTM) procedure; a synchronization signal block (SSB) index indicating a SSB of the candidate cell; and a preamble index of a preamble; and receiving, via a physical random access channel (PRACH) occasion corresponding to the SSB of the candidate cell from the wireless device, the preamble, wherein an uplink transmission power of the preamble is determined by the wireless device based on a measurement of a pathloss of the SSB.

Clause 48. A method comprising: receiving, by a wireless device via a serving cell, a physical downlink control channel (PDCCH) order indicating a transmission of a first preamble on a candidate cell for a layer 1 and 2 triggered mobility (LTM) procedure; determining, in response to the transmission of the first preamble overlapping in time with a transmission of a second preamble on a primary cell (PCell), to prioritize power allocation to the transmission of the first preamble on the candidate cell over the transmission of the second preamble on the PCell; allocating, based on the determining, a first power to the first preamble and a second power to the second preamble; transmitting the first preamble via the candidate cell with the first power; and transmitting the second preamble via the PCell with the second power.

Clause 49. The method of clause 48, wherein the wireless device allocates the first power and the second power so that a total transmit power comprising the first power and the second power is smaller than or equal to a configured maximum power value of the wireless device.

Clause 50. The method of clause 48 or clause 49, wherein the candidate cell is a non-serving cell different from the PCell.

Clause 51. The method of any one of clauses 48 to 50, wherein the second preamble via the PCell is triggered by at least one of: a second PDCCH order received via the PCell; a beam failure recovery procedure on the PCell; and an initial random access (RA) procedure.

Clause 52. The method of any one of clauses 48 to 51, wherein the wireless device determines the first power, for the first preamble on the candidate cell, based on a pathloss measurement of a synchronization signal block (SSB) of a plurality of SSBs of the candidate cell.

Clause 53. The method of clause 52, wherein the SSB is indicated by the PDCCH order.

Clause 54. The method of any one of clauses 48 to 53, wherein the PDCCH order indicates the candidate cell from a plurality of candidate cells configured for the LTM procedure.

Clause 55. The method of any one of clauses 48 to 54, wherein the wireless device determines the second power, for the second preamble on the PCell, based on a pathloss measurement of a pathloss reference signal of the PCell.

Clause 56. The method of clause 55, wherein the pathloss reference signal of the PCell comprises at least one of: a SSB of a plurality of SSBs of the PCell; and a channel state information reference signal (CSI-RS) of a plurality of CSI-RSs of the PCell.

Clause 57. The method of any one of clauses 48 to 56, wherein the serving cell is a PCell.

Clause 58. The method of any one of clauses 48 to 57, wherein the allocating the first power and the second power comprises: allocating the first power not exceeding the configured maximum power value; and allocate the second power not exceeding the remaining power determined based on the configured maximum power minus the first power.

Clause 59. An apparatus comprising one or more processors and memory storing instructions that, when executed by the one or more processors, cause the apparatus at least to perform the method according to any one of clauses 1-58.

Clause 60. A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors of a device, cause the device to perform the method according to any one of clauses 1-58.

Clause 61. An apparatus comprising means for performing the method according to any one of clauses 1-58.

Clause 62. An apparatus comprising circuitry configured to perform the method according to any one of clauses 1-58.

Clause 63. A computer program product encoding instructions for performing the method according to any one of clauses 1-58.

Claims

1. A wireless device comprising: one or more processors; andmemory storing instructions that, when executed by the one or more processors, cause the wireless device to:receive, via a serving cell, one or more radio resource control (RRC) messages comprising configuration parameters of a candidate cell for a layer 1/2 triggered mobility (LTM) procedure, wherein the configuration parameters indicate a transmission power of a synchronization signal block (SSB) transmitted via the candidate cell;receive a physical downlink control channel (PDCCH) order comprising: a cell indicator indicating the candidate cell;an SSB index indicating the SSB of SSBs of the candidate cell; anda preamble index of a preamble; andtransmit, via a physical random access channel (PRACH) occasion corresponding to the SSB of the candidate cell, the preamble using an uplink transmission power based on a measurement of a pathloss, wherein the pathloss is determined based on: the transmission power of the SSB; anda layer 3 filtered reference signal received power (RSRP) of the SSB.

2. The wireless device of claim 1, wherein the configuration parameters further indicate random access channel (RACH) resources for an early timing advance acquisition (ETA) procedure of the LTM procedure.

3. The wireless device of claim 2, wherein the PDCCH order triggers the ETA procedure for the candidate cell for the LTM procedure.

4. The wireless device of claim 2, wherein the instructions further cause the wireless device to transmit the preamble for the ETA procedure and via the PRACH occasion, wherein the PRACH occasion is selected from the RACH resources corresponding to the SSB.

5. The wireless device of claim 1, wherein the instructions further cause the wireless device to switch, based on receiving an LTM cell switch command for the LTM procedure, a primary cell (PCell) from the serving cell to the candidate cell.

6. The wireless device of claim 5, wherein the LTM cell switch command is a medium access control control element (MAC CE).

7. The wireless device of claim 6, wherein the MAC CE comprises a timing advance value for switching to the candidate cell as the PCell.

8. A method comprising: receiving, by a wireless device via a serving cell, one or more radio resource control (RRC) messages comprising configuration parameters of a candidate cell for a layer 1/2 triggered mobility (LTM) procedure, wherein the configuration parameters indicate a transmission power of a synchronization signal block (SSB) transmitted via the candidate cell;receiving a physical downlink control channel (PDCCH) order comprising: a cell indicator indicating the candidate cell;an SSB index indicating the SSB of SSBs of the candidate cell; anda preamble index of a preamble; andtransmitting, via a physical random access channel (PRACH) occasion corresponding to the SSB of the candidate cell, the preamble using an uplink transmission power based on a measurement of a pathloss, wherein the pathloss is determined based on:the transmission power of the SSB; anda layer 3 filtered reference signal received power (RSRP) of the SSB.

9. The method of claim 8, wherein the configuration parameters further indicate random access channel (RACH) resources for an early timing advance acquisition (ETA) procedure of the LTM procedure.

10. The method of claim 9, wherein the PDCCH order triggers the ETA procedure for the candidate cell for the LTM procedure.

11. The method of claim 9, further comprising transmitting the preamble for the ETA procedure and via the PRACH occasion, wherein the PRACH occasion is selected from the RACH resources corresponding to the SSB.

12. The method of claim 8, further comprising switching, based on receiving an LTM cell switch command for the LTM procedure, a primary cell (PCell) from the serving cell to the candidate cell.

13. The method of claim 12, wherein the LTM cell switch command is a medium access control control element (MAC CE).

14. The method of claim 13, wherein the MAC CE comprises a timing advance value for switching to the candidate cell as the PCell.

15. A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors of a wireless device, cause the wireless device to: receive, via a serving cell, one or more radio resource control (RRC) messages comprising configuration parameters of a candidate cell for a layer 1/2 triggered mobility (LTM) procedure, wherein the configuration parameters indicate a transmission power of a synchronization signal block (SSB) transmitted via the candidate cell;receive a physical downlink control channel (PDCCH) order comprising: a cell indicator indicating the candidate cell;an SSB index indicating the SSB of SSBs of the candidate cell; anda preamble index of a preamble; andtransmit, via a physical random access channel (PRACH) occasion corresponding to the SSB of the candidate cell, the preamble using an uplink transmission power based on a measurement of a pathloss, wherein the pathloss is determined based on:the transmission power of the SSB; anda layer 3 filtered reference signal received power (RSRP) of the SSB.

16. The non-transitory computer-readable medium of claim 15, wherein the configuration parameters further indicate random access channel (RACH) resources for an early timing advance acquisition (ETA) procedure of the LTM procedure.

17. The non-transitory computer-readable medium of claim 16, wherein the PDCCH order triggers the ETA procedure for the candidate cell for the LTM procedure.

18. The non-transitory computer-readable medium of claim 16, wherein the instructions further cause the wireless device to the instructions further cause the wireless device to transmit the preamble for the ETA procedure and via the PRACH occasion, wherein the PRACH occasion is selected from the RACH resources corresponding to the SSB.

19. The non-transitory computer-readable medium of claim 15, wherein the instructions further cause the wireless device to switch, based on receiving an LTM cell switch command for the LTM procedure, a primary cell (PCell) from the serving cell to the candidate cell.

20. The non-transitory computer-readable medium of claim 19, wherein the LTM cell switch command is a medium access control control element (MAC CE); and wherein the MAC CE comprises a timing advance value for switching to the candidate cell as the PCell.