Patent Application
20250106845
The disclosure relates to the operation of a terminal and a base station in a wireless communication system. Specifically, the disclosure relates to a method for activating and indicating a plurality of transmission and reception beams in a wireless communication system and a device performing the same.
Fifth generation (5G) mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in “Sub 6 gigahertz (GHz)” bands, such as 3.5 GHZ, but also in “Above 6 GHz” bands referred to as millimeter wave (mmWave) including 28 GHz and 39 GHz. In addition, it has been considered to implement sixth generation (6G) mobile communication technologies (referred to as Beyond 5G systems) in terahertz bands (for example, 95 GHz to 3 terahertz (THz) bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.
At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced mobile broadband (eMBB), ultra reliable low latency communications (URLLC), and massive machine-type communications (mMTC), there has been ongoing standardization regarding beamforming and massive multiple input-multiple output (MIMO) for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mm Wave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of band-width part (BWP), new channel coding methods, such as a low density parity check (LDPC) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.
Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies, such as vehicle-to-everything (V2X) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, new radio unlicensed (NR-U) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR user equipment (UE) power saving, non terrestrial network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.
Moreover, there has been ongoing standardization in air interface architecture/protocol regarding technologies, such as industrial Internet of things (IIoT) for supporting new services through interworking and convergence with other industries, integrated access and backhaul (IAB) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and dual active protocol stack (DAPS) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture/service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining network functions virtualization (NFV) and software-defined networking (SDN) technologies, and mobile edge computing (MEC) for receiving services based on UE positions.
When the 5G mobile communication system is commercialized, connected devices being on a rapidly increasing trend are being predicted to be connected to communication networks, and therefore, it is predicted that enhancement of functions and performance of the 5G mobile communication system and integrated operations of the connected devices are required. To this end, new researches are scheduled for extended Reality (XR=AR+VR+MR) for efficiently supporting Augmented Reality (AR), Virtual Reality (VR), and the like, 5G performance improvement and complexity reduction by utilizing artificial intelligence (AI) and machine learning (ML), AI service support, metaverse service support, drone communication, and the like.
Also, such development of the 5G mobile communication system will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as full dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using orbital angular momentum (OAM), and reconfigurable intelligent surface (RIS), but also full-duplex technology for increasing frequency efficiency of the 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI from a design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.
Various embodiments of the disclosure are to provide devices and methods that can effectively provide services in a mobile communication system. Various embodiments of the disclosure are to provide a method for activating and indicating a plurality of transmission and reception beams in a wireless communication system and a device for performing the same.
In order to solve the above problems, an embodiment of the disclosure provides a method of a terminal in a wireless communication system, comprising receiving, from a base station, a radio resource control (RRC) message including information for determination of a transmission configuration indicator (TCI) state, receiving, from the base station, downlink control information (DCI) including information indicating a unified TCI state, in case that multiple TCI states are indicated based on the DCI, determining a TCI state for a physical uplink control channel (PUCCH) based on the information for determination of the TCI state, and transmitting uplink control information to the base station on the PUCCH based on the determined TCI state.
Further, an embodiment of the disclosure provides a method of a base station in a wireless communication system, comprising transmitting, to a terminal, a radio resource control (RRC) message including information for determination of a transmission configuration indicator (TCI) state, transmitting, to the terminal, downlink control information (DCI) including information indicating a unified TCI state, and receiving, from the terminal, uplink control information on a physical uplink control channel (PUCCH) based on the TCI state determined based on multiple TCI states, in case that the multiple TCI states are indicated based on the DCI, the TCI state for the PUCCH is determined based on the information for determination of the TCI state.
Further, an embodiment of the disclosure provides a terminal in a wireless communication system, comprising a transceiver and a controller, wherein the controller controls to receive, from a base station, a radio resource control (RRC) message including information for determination of a transmission configuration indicator (TCI) state, receive, from the base station, downlink control information (DCI) including information indicating a unified TCI state, in case that multiple TCI states are indicated based on the DCI, determine a TCI state for a physical uplink control channel (PUCCH) based on the information for determination of the TCI state, and transmit uplink control information to the base station on the PUCCH based on the determined TCI state.
Further, an embodiment of the disclosure provides a base station in a wireless communication system, comprising a transceiver; and a controller, wherein the controller controls to transmit, to a terminal, a radio resource control (RRC) message including information for determination of a transmission configuration indicator (TCI) state, transmit, to the terminal, downlink control information (DCI) including information indicating a unified TCI state, and receive, from the terminal, uplink control information on a physical uplink control channel (PUCCH) based on the TCI state determined based on multiple TCI states, wherein in case that the multiple TCI states are indicated based on the DCI, the TCI state for the PUCCH is determined based on the information for determination of the TCI state.
According to various embodiments of the disclosure, devices and methods that can effectively provide services in a mobile communication system can be provided.
According to various embodiments of the disclosure, a method for activating and indicating a plurality of transmission and reception beams in a wireless communication system and a device for performing the same can be provided.
Hereinafter, embodiments of the disclosure will be described in detail with reference to the accompanying drawings.
In the following description of embodiments, descriptions of techniques that are well known in the art and not directly related to the disclosure are omitted. This is to clearly convey the gist of the disclosure without obscuring it by omitting any unnecessary explanation.
For the same reason, some elements in the drawings are exaggerated, omitted, or schematically illustrated. Also, actual sizes of respective elements are not necessarily represented in the drawings. In the drawings, the same or corresponding elements are denoted by the same reference numerals.
The advantages and features of the disclosure and ways to achieve them will be apparent by making reference to embodiments as described below in detail in conjunction with the accompanying drawings. However, the disclosure is not limited to the embodiments set forth below, but may be implemented in various different forms. The following embodiments are provided only to completely disclose the disclosure and inform those skilled in the art of the scope of the disclosure, and the disclosure is defined only by the scope of the appended claims. Throughout the specification, the same or like reference numerals designate the same or like elements. In the description of the disclosure, in case that it is determined that a detailed description of related functions or configurations may unnecessarily obscure the subject matter of the disclosure, the detailed description will be omitted. Further, the terms, as will be mentioned later, are defined by taking functionalities in the disclosure into account, but may vary depending on practices or intentions of users or operators. Accordingly, the terms should be defined based on descriptions throughout this specification.
Hereinafter, a base station is an entity that allocates resources to terminals, and may be at least one of a gNode B, an eNode B, a Node B, a base station (BS), a wireless access unit, a base station controller, and a node on a network. A terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing communication functions. In the disclosure, downlink (DL) refers to a radio transmission path for a signal transmitted from a BS to a UE, and uplink (UL) refers to a radio transmission path for a signal transmitted from a UE to a BS. Also, hereinafter, the LTE or LTE-A system may be described as an example, but an embodiment of the disclosure may be applied to other communication systems with similar technical backgrounds or channel types. For example, the 5th generation (5G) mobile communication technologies (new radio, NR) developed since the LTE-A may be included in the systems, and the 5G as herein used may be a concept including the existing LTE, LTE-A, or other similar services. Furthermore, the disclosure will also be applied to different communication systems with some modifications to such an extent that does not significantly deviate from the scope of the disclosure when determined by skilled people in the art.
Herein, it will be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart block(s). These computer program instructions may also be stored in a computer usable or computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer usable or computer-readable memory produce an article of manufacture including instruction means that implement the function specified in the flowchart block(s). The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable data processing apparatus to produce a computer implemented process such that the instructions that execute on the computer or other programmable data processing apparatus provide steps for implementing the functions specified in the flowchart block(s).
Further, each block of the flowchart illustrations may represent a module, segment, or portion of code, which includes one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.
As used herein, the “unit” refers to a software element or a hardware element, such as a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC), which performs a predetermined function. However, the “unit” does not always have a meaning limited to software or hardware. The “unit” may be constructed either to be stored in an addressable storage medium or to execute one or more processors. Therefore, the “unit” includes, for example, elements such as software elements, object-oriented software elements, class elements or task elements, processes, functions, properties, procedures, sub-routines, segments of a program code, drivers, firmware, micro-codes, circuits, data, database, data structures, tables, arrays, and parameters. The elements and functions provided by the “unit” may be either combined into a smaller number of elements and a “unit”, or divided into a larger number of elements and a “unit”. Moreover, the elements and “units” or may be implemented to reproduce one or more central processing units (CPUs) within a device or a security multimedia card. Further, the “unit” in the embodiments may include one or more processors.
Wireless communication systems are evolving from early systems that provide voice-oriented services to broadband wireless communication systems that provide high data rate and high quality packet data services such as 3GPP high speed packet access (HSPA), long term evolution (LTE) or evolved universal terrestrial radio access (E-UTRA), LTE-advanced (LTE-A), LTE-Pro, 3GPP2 high rate packet data (HRPD), ultra mobile broadband (UMB), and IEEE 802.16e communication standards.
As a representative example of such a broadband wireless communication system, an LTE system adopts Orthogonal Frequency Division Multiplexing (OFDM) scheme for downlink (DL) and Single Carrier Frequency Division Multiple Access (SC-FDMA) scheme for uplink (UL). The UL refers to a radio link for a terminal (user equipment (UE)) or mobile station (MS) to transmit data or a control signal to a base station (eNode B or base station (BS)), and the DL refers to a radio link for a BS to transmit data or a control signal to a UE. Such a multiple access scheme allocates and operates time-frequency resources for carrying data or control information for respective users not to overlap each other, i.e., to maintain orthogonality, thereby differentiating each user's data or control information.
As a communication system since the LTE, i.e., the 5G communication system needs to freely reflect various demands from users and service providers and thus support services that simultaneously meet the various demands. The services considered for the 5G communication system may include enhanced Mobile Broadband (eMBB), massive Machine Type Communication (mMTC), Ultra Reliability Low Latency Communication (URLLC), etc.
The eMBB is aimed at providing more enhanced data rates than the LTE, LTE-A or LTE-Pro may support. For example, in the 5G communication system, the eMBB is required to provide 20 Gbps peak data rate in DL and 10 Gbps peak data rate in UL in terms of a single BS. Furthermore, the 5G communication system needs to provide increasing user perceived data rate while providing the peak data rate. To satisfy these requirements, enhancement of various technologies for transmission or reception including multiple-input multiple-output (MIMO) transmission technologies may be required. Also, while the LTE uses a maximum of 20 MHz transmission bandwidth in the 2 GHz band for signal transmission, the 5G communication system may use frequency bandwidth wider than 20 MHz in the 3 to 6 GHz band or in the 6 GHz or higher band, thereby satisfying the data rate required by the 5G communication system.
At the same time, in the 5G communication system, mMTC is considered to support an application service such as an Internet of Things (IoT) application service. In order for the mMTC to provide the IoT efficiently, support for access from massive number of UEs in a cell, enhanced coverage of the UE, extended battery time, reduction in terminal price, etc., are required. Because the IT is equipped in various sensors and devices to provide communication functions, it may need to support a large number of UEs in a cell (e.g., 1,000,000 terminals/km2). Furthermore, a UE supporting the mMTC is more likely to be located in a shadow area, such as underground of a building, which might not be covered by a cell by the nature of the service, so the mMTC requires an even larger coverage than expected for other services provided by the 5G communication system. The UE supporting the mMTC needs to be a low-cost UE, and requires quite long battery life time such as 10 to 15 years because the battery in the UE is hard to be changed frequently.
Finally, URLLC is a mission-critical cellular-based wireless communication service. For example, the URLLC may provide services used for remote control over robots or machinery, industrial automation, unmanned aerial vehicle, remote health care, emergency alert, etc. Accordingly, communication offered by the URLLC requires very low latency and very high reliability. For example, URLLC services may need to satisfy air interface latency to be less than 0.5 millisecond and simultaneously require a packet error rate equal to or lower than 10-5. Hence, for the services supporting the URLLC, the 5G system needs to provide a smaller transmit time interval (TTI) than for other services, and at the same time, design requirements may require allocating a wide range of resources for a frequency band to secure reliability of the communication link.
Those three services in 5G, that is, eMBB, URLLC, and mMTC may be multiplexed in a single system for transmission. In this case, to meet different requirements for the respective services, different transmission or reception schemes and parameters may be used between the services. It is apparent that the 5G is not limited to the above-described three services.
Hereinafter, a frame structure of a 5G system will be described in detail with reference to accompanying drawings.
In
In
Next, bandwidth part (BWP) configuration in the 5G communication system will be described in detail with reference to the drawing.
It is apparent that the configuration information is not limited to the above example, and various parameters related to the bandwidth parts may be configured for the UE in addition to the configuration information. The information may be delivered from the base station to the UE through higher layer signaling, for example, radio resource control (RRC) signaling. At least one bandwidth part among one and a plurality of configured bandwidth parts may be activated. Whether to activate the configured bandwidth part may be semi-statically delivered from the base station to the UE through the RRC signaling, or may be dynamically delivered through downlink control information (DCI).
According to some embodiments, the UE before being RRC-connected may be configured with an initial BWP for the initial access from the base station through the master information block (MIB). More specifically, at an initial access operation, the UE may receive configuration information on a search space and a control resource set (CORESET) in which the PDCCH for receiving remaining system information (RMSI) (or system information block 1 which may correspond to SIB1) that is necessary for the initial access through the MIB. The control resource set and search space being configured through the MIB may be considered as identity (ID) 0, respectively. The base station may notify the UE of configuration information, such as frequency allocation information for control resource set #0, time allocation information, and numerology, through the MIB. Further, the base station may notify the UE of configuration information on monitoring period and monitoring occasion for control resource set #0, that is, configuration information on search space #0, through the MIB. The UE may consider the frequency domain configured as control resource set #0 obtained from the MIB as an initial bandwidth part for the initial access. In this case, the identity (ID) of the initial bandwidth part may be considered as 0.
The configuration for the bandwidth part being supported in the 5G system may be used for various purposes.
According to some embodiments, in case that the bandwidth supported by the UE is smaller than the system bandwidth, this may be supported through the bandwidth part configuration. For example, the base station may configure the frequency location (configuration information 2) of the bandwidth part for the UE, and thus the UE may transmit or receive data in a specific frequency location in the system bandwidth.
Further, according to some embodiments, the base station may configure a plurality of bandwidth parts for the UE for the purpose of supporting different numerologies. For example, in order for a certain UE to support all of data transmission/reception using 15 kHz subcarrier spacing and 30 kHz subcarrier spacing, two bandwidth parts may be configured as 15 kHz and 30 kHz subcarrier spacings. The different bandwidth parts may be frequency-division-multiplexed, and in case of transmitting or receiving data at specific subcarrier spacing, the bandwidth part being configured at the corresponding subcarrier spacing may be activated.
Further, according to some embodiments, the base station may configure the bandwidth part having bandwidths of different sizes for the UE for the purpose of reduction of power consumption of the UE. For example, in case that the UE supports a very large bandwidth, for example, bandwidth of 100 MHz, and always transmit or receive data in the corresponding bandwidth, very large power consumption may occur. In particular, performing of monitoring for unnecessary downlink control channel with a large bandwidth of 100 MHz in a situation of no traffic may be very inefficient from the viewpoint of power consumption. For the purpose of reducing the power consumption of the UE, the base station may configure a bandwidth part of a relatively small bandwidth, for example, the bandwidth part of 20 MHz, to the UE. In a situation of no traffic, the UE may perform a monitoring operation in the 20 MHz bandwidth part, and in case of data occurrence, the UE may transmit or receive data with the 100 MHz bandwidth part in accordance with the instructions of the base station.
As for the method for configuring the bandwidth part, the UEs before the RRC connection may receive configuration information on the initial bandwidth part through the master information block (MIB) at the initial access operation. More specifically, the UE may be configured with the control resource set (CORESET) for the downlink control channel on which the downlink control information (DCI) for scheduling the system information block (SIB) can be transmitted from the MIB on the physical broadcast channel (PBCH). The bandwidth of the control resource set configured as the MIB may be considered as the initial BWP, and the UE may receive the physical downlink shared channel (PDSCH) on which the SIB is transmitted through the configured initial BWP. In addition to the purpose of receiving the SIB, the initial BWP may be utilized for other system information (OSI), paging, and random access.
In case that one or more bandwidth parts are configured for the UE, the base station may instruct the UE to change (or switch, transit) the bandwidth part by using a bandwidth part indicator field in the DCI. As an example, in
As described above, the DCI based bandwidth part change may be indicated by the DCI scheduling the PDSCH or PUSCH, and in case that the UE receives a bandwidth part change request, it is required to perform reception or transmission of the PDSCH or PUSCH being scheduled by the corresponding DCI without difficulty in the changed bandwidth part. For this, requirements for a delay time TBWP required when changing the bandwidth part have been regulated in the standard, and may be defined, for example, as follows.
Note 1
The requirements for the bandwidth part change delay time support type 1 or type 2 in accordance with UE capability. The UE may report a supportable bandwidth part delay time type to the base station.
According to the requirements for the bandwidth part change delay time described above, in case that the UE receives the DCI including the bandwidth part change indicator at slot n, the UE may complete the change to a new bandwidth part indicated by the bandwidth part change indicator at a time that is not later than the slot n+TBWP, and may perform transmission/reception for the data channel being scheduled by the corresponding DCI in the new changed bandwidth part. In case of scheduling the data channel in the new bandwidth part, the base station may determine the time domain resource allocation for the data channel in consideration of the bandwidth part change delay time (TBWP) of the UE. That is, when scheduling the data channel with the new bandwidth part, in the method for determining the time domain resource allocation for the data channel, the base station may schedule the corresponding data channel after the bandwidth part change delay time. Accordingly, the UE may not expect that the DCI indicating the bandwidth part change indicates a slot offset (K0 or K2) value that is smaller than the bandwidth part change delay time (TBWP).
If the UE receives the DCI (e.g., DCI format 1_1 or 0_1) indicating the bandwidth part change, the UE may not perform any transmission or reception during a corresponding time period from the third symbol of the slot having received the PDCCH including the corresponding DCI to a start time point of the slot indicated by the slot offset (K0 or K2) value indicated by the time domain resource allocation indicator field in the corresponding DCI. For example, in case that the UE has received the DCI indicating the bandwidth part change at slot n, and the slot offset value indicated by the corresponding DCI is K, the UE may not perform any transmission or reception from the third symbol of slot n to the symbol (e.g., last symbol of slot n+K−1) before slot n+K.
Next, a synchronization signal (SS)/PBCH block in the 5G will be described.
The SS/PBCH block may mean a physical layer channel block composed of a Primary SS (PSS), a Secondary SS (SSS), and a PBCH. Specifically, it is as follows.
The UE may detect a PSS and an SSS in an initial access phase and may decode a PBCH. The UE may obtain an MIB from the PBCH and be therefrom configured with a control resource set #0 (which may correspond to a control resource set whose control resource set index is 0). The UE may perform monitoring on the control resource set #0, assuming that a selected SS/PBCH block and a Demodulation Reference signal (DMRS) transmitted in the control resource set #0 are quasi-co-located (QCLed). The UE may receive system information via downlink control information transmitted in the control resource set #0. The UE may obtain configuration information related to a Random Access Channel (RACH) required for an initial access from the received system information. The UE may transmit a Physical RACH (PRACH) to the base station considering the selected SS/PBCH block index, and the base station receiving the PRACH may obtain the SS/PBCH block index selected by the UE. The base station may know which block the UE has selected from the SS/PBCH blocks and monitors the control resource set #0 related thereto.
Next, downlink control information (DCI) in a 5G system will be described in detail.
Scheduling information of uplink data (or a Physical Uplink Shared Channel (PUSCH)) or downlink data (or a Physical Downlink Shared Channel (PDSCH)) in the 5G system is delivered from a base station to a UE via the DCI. The UE may monitor a DCI format for fallback and a DCI format for non-fallback for the PUSCH or PDSCH. The DCI format for fallback may be composed of fixed fields predefined between the base station and the UE, and the DCI format for non-fallback may include configurable fields.
DCI may be transmitted via a Physical Downlink Control Channel (PDCCH) which is a physical downlink control channel, after passing a channel coding and modulation process. A Cyclic Redundancy Check (CRC) may be added to a payload of the DCI message, and the CRC may be scrambled with a Radio Network Temporary Identifier (RNTI) which corresponds to identity of the UE. Different RNTIs may be used for the purposes of the DCI message, e.g., UE-specific data transmission, power control command, or random access response. That is, the RNTI is not explicitly transmitted, but the RNTI is included in a CRC calculation process and transmitted. Upon receiving the DCI message transmitted on the PDCCH, the UE may identify the CRC using the allocated RNTI, and if the CRC identification result is correct, the UE may be aware that the corresponding message has been transmitted to the UE.
For example, DCI scheduling a PDSCH for System Information (SI) may be scrambled with an SI-RNTI. DCI scheduling a PDSCH for a Random Access Response (RAR) message may be scrambled with an RA-RNTI. DCI scheduling a PDSCH for a paging message may be scrambled with a P-RNTI. DCI notifying a Slot Format Indicator (SFI) may be scrambled with an SFI-RNTI. DCI notifying Transmit Power Control (TPC) may be scrambled with a TPC-RNTI. DCI scheduling UE-specific PDSCH or PUSCH may be scrambled with a Cell RNTI (C-RNTI).
A DCI format 0_0 may be used as fallback DCI for PUSCH scheduling, wherein a CRC is scrambled by a C-RNTI. DCI format 0_0 in which a CRC is scrambled by a C-RNTI may include the information as shown below.
DCI format 0_1 may be used for non-fallback DCI for scheduling a PUSCH, in which case the CRC may be scrambled with a C-RNTI. DCI format 0_1, in which the CRC is scrambled with the C-RNTI, may include, for example, the following information
DCI format 1_0 may be used for fallback DCI for scheduling a PDSCH in which case the CRC may be scrambled with a C-RNTI. DCI format 1_0 in which the CRC is scrambled with the C-RNTI may include, for example, the following information.
DCI format 1_1 may be used for non-fallback DCI for scheduling a PDSCH, in which case the CRC may be scrambled with a C-RNTI. DCI format 1_1, in which the CRC is scrambled with the C-RNTI, may include, for example, the following information.
Hereinafter, the downlink control channel in the 5G communication system will be described in more detail with reference to the drawings.
The above described control resource sets in 5G may be configured through higher layer signaling (for example, system information, a master information block (MIB), or radio resource control (RRC) signaling) in the UE by the base station. Configuring the control resource set in the UE may mean providing information such as the identity of the control resource set, the frequency location of the control resource set, and the symbol length of the control resource set. For example, the following information may be included.
In Table 8, tci-StatesPDCCH (simply, referred to as a transmission configuration indication (TCI) state) configuration information may include information on one or a plurality of synchronization signal (SS)/physical broadcast channel (PBCH) block indexes or channel state information reference signal (CSI-RS) indexes having the quasi co-location (QCL) relationship with DMRS transmitted in the corresponding control resource set.
According to
As illustrated in
The basic unit of the downlink control channel illustrated in
The search spaces may be classified into a common search space and a terminal (UE)-specific search space. The UEs in a predetermined group or all UEs may search for a common search space of the PDCCH in order to receive cell-common control information such as dynamic scheduling of system information or paging messages. For example, PDSCH scheduling allocation information for transmission of an SIB including information on the service provider of a cell, etc. may be received by searching a common search space of the PDCCH. In the case of the common search space, the UEs in a predetermined group or all UEs should receive the PDCCH, so that the common search space may be defined as a set of pre-arranged CCEs. Scheduling allocation information of the UE-specific PDSCH or PUSCH may be received by searching a UE-specific search space of the PDCCH. The UE-specific search space may be defined in a UE-specific manner as a UE identity and a function of various system parameters.
In the 5G, parameters for the PDCCH search space may be configured in the UE by the base station through higher layer signaling (for example, SIB, MIB, or RRC signaling). For example, the base station may configure, in the UE, the number of PDCCH candidates at each aggregation level L, a monitoring period of the search space, a monitoring occasion in units of symbols within the slot for the search space, a search space type (a common search space or a UE-specific search space), a combination of a DCI format and an RNTI to be monitored in the corresponding search space, a control resource set index for monitoring the search space, and the like. For example, the following information may be included.
The base station may configure one or a plurality of search space sets in the UE according to the configuration information. For example, the base station may configure search space set 1 and search space 2 in the UE, and the configuration may be performed such that DCI format A, scrambled by an X-RNTI in search space set 1, is monitored in the common search space and DCI format B scrambled by a Y-RNTI in search space set 2 is monitored in the UE-specific search space.
According to the configuration information, there may be one or a plurality of search space sets in the common search space or the UE-specific search space. For example, search space set #1 and search space set #2 may be configured as common search spaces, and search space set #3 and search space set #4 may be configured as UE-specific search spaces.
In the common search space, the following combinations of DCI formats and RNTIs may be monitored, but it is not apparently limited thereto.
In the UE-specific search space, the following combinations of DCI formats and RNTIs may be monitored, but is not apparently limited thereto.
The above specified RNTIs may comply with the following definition and purpose.
The above DCI formats may comply with the following definition.
In the 5G, with control resource set p and search space set s, a search space at the aggregation level L may be expressed as in Equation 1.
Yp,n
In the 5G, a plurality of search space sets may be configured with different parameters (e.g., parameters as in table 9). Accordingly, the set of search spaces to be monitored by the UE may vary at each point in time. For example, when the search space set #1 is configured with X-slot periodicity and the search space set #2 is configured with Y-slot periodicity, where X and Y are different, the UE may monitor both the search space set #1 and the search space set #2 in a particular slot, and monitor one of the search space set #1 and the search space set #2 in another particular slot.
The UE may perform a UE capability report regarding a case where the UE has a plurality of PDCCH monitoring locations in a slot, for each subcarrier spacing, and at this time, may use a concept of span. The span denotes consecutive symbols for the UE to monitor the PDCCH in the slot, and each PDCCH monitoring location is within one span. The span may be represented as (X, Y), and here, X denotes the minimum number of symbols between first symbols of two consecutive spans, and Y denotes the number of consecutive symbols for monitoring the PDCCH in one span. Here, the UE may monitor the PDCCH in a section of the span from the first symbol to a Y symbol, in the span.
Regarding the span, (X, Y)=(7, 4), (4, 3), and (2, 2), and these three cases are respectively indicated by May 1, 2000, May 1, 2005, and May 1, 2010 in
The slot location in which the above-described common search space and UE-specific search space are located is indicated by the parameter, monitoringSymbolsWithinSlot in Table 11-1, and the symbol location in the slot is indicated by a bitmap through the parameter, monitoringSymbolsWithinSlot in Table 9. Meanwhile, the symbol location within a slot in which the UE is able to monitor the search space may be reported to the base station through the following UE capabilities.
UE capability 2 (hereinafter referred to as
The UE may report whether or not to support the above-described UE capability 2 and/or UE capability 3 and related parameters to the base station. The base station may perform resource allocation in the time axis for a common search space and UE-specific search space, based on the reported UE capability. During the resource allocation, the base station may not allocate the MO at the location where the UE is unable to monitor the same.
In the case where a plurality of search space sets is configured for the UE, the following conditions may be considered in a method for determining a search space set to be monitored by the UE.
If a value monitoringCapabilityConfig-r16, which is higher layer signaling, is configured as r15monitoringcapability, the UE defines the maximum values of the number of PDCCH candidates capable of being monitored and the number of CCEs constituting the entire search space (here, the entire search space indicates an entire CCE set corresponding to the union area of a plurality of search space sets) for each slot, and if the value monitoringCapabilityConfig-r16 is configured as r16monitoringcapability, the UE defines the maximum values of the number of PDCCH candidates capable of being monitored and the number of CCEs constituting the entire search space (here, the entire search space indicates an entire CCE set corresponding to the union area of a plurality of search space sets) for each span.
According to the configuration value of higher layer signaling described above, Mu, the maximum number of PDCCH candidates capable of being monitored by the UE, may be configured according to Table 12-1 below in case that it is defined based on a slot, and may be configured according to Table 12-2 below in case that it is defined based on a span, in a cell having a subcarrier spacing of 15.2p KHz.
According to the configuration value of higher layer signaling described above, Cu, the maximum number of CCEs constituting the entire search space (here, the entire search space indicates the entire CCE set corresponding to the union area of a plurality of search space sets), may be configured according to Table 12-3 below in case that it is defined based on a slot, and may be configured according to Table 12-4 below in case that it is defined based on a span, in a cell having a subcarrier spacing of 15.2u kHz.
For convenience of explanation, a situation that satisfies both conditions 1 and 2 at a specific time is defined as “condition A”. Therefore, a situation that does not satisfy condition A may indicate that the situation does not satisfy at least one of conditions 1 and 2 above.
Condition A may not be satisfied at a specific time depending on the configuration of search space sets by the base station. In case that condition A is not satisfied at a specific time, the UE may select and monitor only some of the search space sets configured to satisfy condition A at the corresponding time, and the base station may transmit a PDCCH to the selected search space sets.
Selection of some search spaces from among the entire configured search space sets may be performed according to the following methods.
In case that condition A for a PDCCH is not satisfied at a specific time (slot), the UE (or the base station) may preferentially select the search space set in which the search space type is configured as a common search space from among the search space sets existing at the corresponding time, instead of the search space set in which the search space type is configured as a UE-specific search space.
In case that all search space sets configured as a common search space are selected (i.e., in case that condition A is satisfied even after selecting all search spaces configured as a common search space), the UE (or the base station) may select the search space sets configured as a UE-specific search space. In this case, in case that there are a plurality of search space sets configured as a UE-specific search space, the search space set having a lower search space set index may have a higher priority. The UE or base station may select UE-specific search space sets within a range in which condition A is satisfied in consideration of priority.
Discontinuous reception (DRX) is an operation in which a UE using a service discontinuously receives data in an RRC-connected state in which a radio link is configured between a base station and the UE. When the DRX is applied, the UE may turn on a receiver at a specific time point to monitor a control channel, and when there is no data received for a certain period, the UE may turn off the receiver to reduce power consumption of the UE. The DRX operation may be controlled by an MAC layer device, based on various parameters and timers.
With reference to
Here, drx-onDuration Timer, drx-Inactivity Timer, drx-Retransmission TimerDL, drx-Retransmission TimerUL, and ra-ContentionResolutionTimer are timers having values configured by the base station, and have a function to configure the UE to monitor the PDCCH in a situation satisfying a certain condition.
A drx-onDurationTimer 615 is a parameter for configuring a minimum time during which the UE is awake in a DRX cycle. A drx-Inactivity Timer 620 is a parameter for configuring a time during which the UE is additionally awake in a case 630 where the PDCCH indicating new uplink transmission or downlink transmission is received. A drx-RetransmissionTimerDL is a parameter for configuring a maximum time during which the UE is awake to receive downlink retransmission in a downlink HARQ procedure. A drx-RetransmissionTimerUL is a parameter for configuring a maximum time during which the UE is awake to receive a grant for uplink retransmission in an uplink HARQ procedure. The drx-onDurationTimer, the drx-Inactivity Timer, the drx-Retransmission TimerDL, and the drx-RetransmissionTimerUL may be configured by, for example, a time, the number of subframes, or the number of slots. A ra-ContentionResolutionTimer is a parameter for monitoring a PDCCH in a random access procedure.
An inactive time 610 is a time configured not to monitor and/or receive a PDCCH in the DRX operation, and may be remaining time excluding the active time 605 from the entire time during which the DRX operation is performed. When the UE does not monitor the PDCCH during the active time 605, the UE may enter a sleep or inactive state to reduce power consumption.
The DRX cycle denotes a period at which the UE wakes up and monitors the PDCCH. In other words, the DRX cycle denotes a time interval between monitoring of the PDCCH by the UE and monitoring of a next PDCCH, or an on-duration occurrence period. There are two types of DRX cycles, which are a short DRX cycle and a long DRX cycle. The short DRX cycle may be optionally applied.
A long DRX cycle 625 is a long cycle among the two types of DRX cycles configured to the UE. While the UE operates in long DRX, the UE restarts the drx-onDuration Timer 615 at a time point after the long DRX cycle 625 has passed from a start point (e.g., a starting symbol) of the drx-onDuration Timer 615. In case that the UE operates in the long DRX cycle 625, the UE may start the drx-onDuration Timer 615 in a slot after a drx-SlotOffset in a subframe satisfying Equation 2 below. Here, the drx-SlotOffset implies a delay before the drx-onDurationTimer 615 is started. The drx-SlotOffset may be configured by, for example, a time or the number of slots.
[(SFN×10)+subframe number]modulo(drx-LongCycle)=drx-StartOffset Equation 2
Here, a drx-LongCycleStartOffset may be used to define a subframe in which a long DRX cycle 625 starts, and a drx-StartOffset may be used to define a subframe in which the long DRX cycle 625 starts. For example, the drx-LongCycleStartOffset may be configured by, for example, a time, the number of subframes, or the number of slots.
In a wireless communication system, one or more different antenna ports (may be replaced by one or more channels, signals, or combinations thereof, but for convenience of description, may be collectively referred to as different antenna ports) may be associated with each other through a quasi co-location (QCL) configuration as Table 10 below. A TCI state is for notifying about a QCL relationship between a PDCCH (or PDCCH DMRS) and another RS or channel. When a reference antenna port A (reference RS #A) and another target antenna port B (target RS #B) are QCLed to each other, it may mean that the UE is allowed to apply all or some of large-scale channel parameters estimated in the antenna port A to perform a channel measurement in the antenna port B. The QCL may require different parameters to be associated according to situations including 1) time tracking affected by average delay and delay spread, 2) frequency tracking affected by a Doppler shift and Doppler spread, 3) radio resource management (RRM) affected by an average gain, and 4) beam management (BM) affected by a spatial parameter. Accordingly, NR supports four types of QCL relationships shown in Table 13 below.
The spatial RX parameter may collectively refer to some or all of various parameters such as an angle of arrival (AoA), a power Angular Spectrum (PAS) of AoA, an angle of departure (AoD), a PAS of AoD, a transmit/receive channel correlation, transmit/receive beamforming, and a spatial channel correlation.
The QCL relationship may be configured to the UE through an RRC parameter TCI-State and QCL-Info as shown in Table 14 below. With reference to Table 14, the base station may configure the UE with at least one TCI state to notify the UE about a maximum of two QCL relationships (qcl-Type1 and qcl-Type2) regarding an RS referring to ID of the TCI state, that is, a target RS. Here, each of pieces of QCL information (QCL-Info) included in the TCI state may include a serving cell index and BWP index of a reference RS indicated by a corresponding piece of QCL information, a type and ID of the reference RS, and a QCL type as shown in Table 13 above.
With reference to
Tables 15-1 to 15-5 below indicate valid TCI state configurations according to the types of target antenna ports.
Table 15-1 indicates valid TCI state configurations in case that a target antenna port is CSI-RS for tracking (TRS). The TRS denotes, from among CSI-RSs, an NZP CSI-RS in which a repetition parameter is not configured and trs-Info is configured to be true. A configuration 3 in Table 15-1 may be used for aperiodic TRS.
Table 15-2 indicates valid TCI state configurations in case that a target antenna port is CSI-RS for CSI. The CSI-RS for CSI denotes, from among CSI-RSs, an NZP CSI-RS in which a parameter indicating repetition (for example, a repetition parameter) is not configured and trs-Info is also not configured to be true.
Table 15-3 indicates valid TCI state configurations in case that a target antenna port is CSI-RS for beam management (BM) (identical to CSI-RS for L1 RSRP reporting). The CSI-RS for BM denotes, from among CSI-RSs, an NZP CSI-RS in which a repetition parameter is configured to have a value of on or off, and trs-Info is not configured to be true.
Table 15-4 indicates valid TCI state configurations in case that a target antenna port is PDCCH DMRS.
Table 15-5 indicates valid TCI state configurations in case that a target antenna port is PDSCH DMRS.
A representative QCL configuration method by Tables 15-1 to 15-5 above includes managing a target antenna port and reference antenna port for each stage by configuring “SSB”-> “TRS”-> “CSI-RS for CSI, CSI-RS for BM, PDCCH DMRS, or PDSCH DMRS.” Accordingly, it is possible to aid a reception operation of a UE by associating statistical characteristics measurable from an SSB and TRS with each antenna port.
In detail, a combination of TCI states applicable to a PDCCH DMRS antenna port is as Table 16 below. A fourth row in Table 16 is a combination assumed by a UE before an RRC configuration, and a configuration after RRC is impossible.
In the NR, the hierarchical signaling method is supported as illustrated in
With reference to
With reference to
The base station may configure, to the UE, one or a plurality of TCI states with respect to a specific CORESET, and may activate one of the configured TCI states through an MAC CE activation command. For example, {TCI state #0, TCI state #1, TCI state #2} is configured to CORESET #1 as TCI states, and the base station may transmit, to the UE, a command for activating the TCI state #0 as a TCI state for the CORESET #1 via an MAC CE. Based on the activation command regarding the TCI state, received via the MAC CE, the UE may correctly receive a DMRS in the corresponding CORESET, based on QCL information in the activated TCI state.
With respect to a CORESET (CORESET #0) configured to have an index of 0, when the UE has failed to receive an MAC CE activation command regarding a TCI state of the CORESET #0, it may be assumed that the UE is QCLed with an SS/PBCH block identified during an initial access process or a non-contention-based random access process that is not triggered by a PDCCH command, with respect to a DMRS transmitted in the CORESET #0.
With respect to a CORESET (CORESET #X) configured to have an index of a value other than zero, when a TCI state regarding the CORESET #X is failed to be configured to the UE, or when one or more TCI states are configured to the UE, but the UE has failed to receive an MAC CE activation command for activating one of the TCI states, it may be assumed that the UE is QCLed with an SS/PBCH block identified in an initial access process, with respect to a DMRS transmitted in the CORESET #X.
Hereinafter, a rate matching operation and a puncturing operation will be described in detail.
In case that a time for transmitting a certain symbol sequence A and frequency resource A overlap a certain time and frequency resource B, the rate matching or puncturing operation may be considered as a transmission/reception operation in consideration of resource C in an area in which resource A and resource B overlap each other. The detailed operation may follow the following contents.
The base station may map channel A on only the remaining resource area excluding resource C corresponding to an area overlapping resource B among the whole resource A, being intended to transmit symbol sequence A to the UE, and transmit the mapped symbol sequence A. For example, in case that symbol sequence A is composed of {symbol #1, symbol #2, symbol #3, symbol #4}, resource A is composed of {resource #1, resource #2, resource #3, resource #4}, and resource B is composed of {resource #3, resource #5}, the base station may sequentially map the symbol sequence A on {resource #1, resource #2, resource #4} being the remaining resources excluding {resource #3} corresponding to resource C among the resource A, and may transmit the mapped symbol sequence A. As a result, the base station may map the symbol sequence {symbol #1, symbol #2, symbol #3} on the {resource #1, resource #2, resource #4}, respectively, and may transmit the mapped symbol sequence.
The UE may determine resource A and resource B from scheduling information for symbol sequence A from the base station, and through this, may determine resource C that is the area in which resource A and resource B overlap each other. The UE may receive symbol sequence A on the assumption that symbol sequence A is mapped on the remaining area excluding resource C among the whole resource A, and the mapped symbol sequence A is transmitted. For example, in case that symbol sequence A is composed of {symbol #1, symbol #2, symbol #3, symbol #4}, resource A is composed of {resource #1, resource #2, resource #3, resource #4}, and resource B is composed of {resource #3, resource #5}, the UE may receive the symbol sequence A on the assumption that the symbol sequence A is mapped on {resource #1, resource #2, resource #4} being the remaining resources excluding {resource #3} corresponding to resource C among the resource A. As a result, the UE may perform the subsequent series of reception operations on the assumption that the symbol sequence {symbol #1, symbol #2, symbol #3} is respectively mapped on the {resource #1, resource #2, resource #4}, and is transmitted.
In case that resource C corresponding to an area overlapping resource B among the whole resource A, being intended to transmit symbol sequence A to the UE, is present, the base station may map the symbol sequence A on the whole of resource A, but may not perform transmission in the resource area corresponding to resource C, and may perform transmission only with respect to the remaining resource area excluding resource C among the resource A. For example, in case that symbol sequence A is composed of {symbol #1, symbol #2, symbol #3, symbol #4}, resource A is composed of {resource #1, resource #2, resource #3, resource #4}, and resource B is composed of {resource #3, resource #5}, the base station may map the symbol sequence A {symbol #1, symbol #2, symbol #3, symbol #4} on the resource A {resource #1, resource #2, resource #3, resource #4}, respectively, and may transmit only the symbol sequence {symbol #1, symbol #2, symbol #4} corresponding to the remaining resource {resource #1, resource #2, resource #4} excluding {resource #3} corresponding to resource C among the resource A, but may not transmit {symbol #3} mapped on {resource #3} corresponding to resource C. As a result, the base station may map the symbol sequence {symbol #1, symbol #2, symbol #4} on the {resource #1, resource #2, resource #4}, respectively, and may transmit the mapped symbol sequence.
The UE may determine resource A and resource B from scheduling information for symbol sequence A from the base station, and through this, may determine resource C that is the area in which resource A and resource B overlap each other. The UE may receive symbol sequence A on the assumption that symbol sequence A is mapped on the whole resource A, but is transmitted only in the remaining area excluding resource C among the resource area A. For example, in case that symbol sequence A is composed of {symbol #1, symbol #2, symbol #3, symbol #4}, resource A is composed of {resource #1, resource #2, resource #3, resource #4}, and resource B is composed of {resource #3, resource #5}, the UE may assume that the symbol sequence A {symbol #1, symbol #2, symbol #3, symbol #4} is respectively mapped on the resource A {resource #1, resource #2, resource #3, resource #4}, but {symbol #3} mapped on {resource #3} corresponding to resource C is not transmitted, and may receive the symbol sequence A on the assumption that the symbol sequence A is mapped on symbol sequence {symbol #1, symbol #2, symbol #4} corresponding to the remaining resources {resource #1, resource #2, resource #4} excluding {resource #3} corresponding to resource C among the resource A, and the mapped symbol sequence A is transmitted. As a result, the UE may perform the subsequent series of reception operations on the assumption that the symbol sequence {symbol #1, symbol #2, symbol #4} is mapped on the {resource #1, resource #2, resource #4}, and the mapped symbol sequence is transmitted.
A method for configuring a rate matching resource for the rate matching of a 5G communication system is described below. Rate-matching means that the size of a signal is controlled by taking into consideration the amount of resources capable of transmitting the signal. For example, the rate matching of a data channel means that the amount of data is adjusted without mapping and transmitting the data channel with respect to a given time and frequency resource area.
In
The base station may dynamically notify the UE whether to perform the rate matching of the data channel through DCI in the configured rate matching resource part through additional configuration (corresponding to “a rate matching indicator” in the above-described DCI format). Specifically, the base station may select and group some of the configured rate matching resources into a rate matching resource group, and may instruct the UE whether to perform rate matching of a data channel for each rate matching resource group through the DCI by using the bitmap method. For example, in case that 4 rate matching resources RMR #1, RMR #2, RMR #3, and RMR #4 are configured, the base station may configure RMG #1={RMR #1, RMR #2} and RMG #2={RMR #3, RMR #4} as the rate matching groups, and may instruct the UE whether to perform rate matching in RMG #1 and RMG #2, respectively, as the bitmap, by using 2 bits in a DCI field. For example, the base station may configure the bits to “1” in case that the rate matching should be performed, and may configure the bits to “0” in case that the rate matching should not be performed.
In the 5G, granularity of “RB symbol level” and “RE level” is supported as a method for configuring the above-described rate matching resource to the UE. More specifically, the following configuration method may follow.
The UE may be configured with maximally 4 RateMatchPattern by bandwidth parts through higher layer signaling, and one RateMatchPattern may include the following contents.
As a reserved resource in a bandwidth part, it may include a resource on which time and frequency resource areas of the corresponding reserved resource are configured through a combination of a bitmap of an RB level and a bitmap of a symbol level on frequency axis. The reserved resource may be spanned through one or two slots. A time domain pattern (periodicity AndPattern) in which the time and frequency areas composed of a bitmap pair of the RB level and symbol level are repeated may be additionally configured.
A resource area corresponding to time and frequency domain resource areas configured by a control resource set in the bandwidth part and a time domain pattern configured by search space configuration in which the corresponding resource area is repeated may be included.
The UE may be configured with the following contents through higher layer signaling.
Next, the rate match process for the above-described LTE CRS will be described in detail. For the coexistence of long term evolution (LTE) and new RAT (NR) (LTE-NR coexistence), NR provides a function of configuring a cell specific reference signal (CRS) pattern of LTE to an NR UE. More specifically, the CRS pattern may be provided by RRC signaling including at least one parameter in ServingCellConfig information element (IE) or ServingCellConfigCommon IE. The parameter may include lte-CRS-ToMatchAround, Ite-CRS-PatternList1-r16, Ite-CRS-PatternList2-r16, crs-RateMatch-PerCORESETPoolIndex-r16, and the like, for example.
Rel-15 NR provides a function in which one CRS pattern can be configured per serving cell through the lte-CRS-ToMatchAround parameter. In Rel-16 NR, the above function has been extended to enable configuration of a plurality of CRS patterns per serving cell. More specifically, one CRS pattern per one LTE carrier may be configured in a single transmission and reception point (TRP) configuration UE, and two CRS patterns per one LTE carrier may be configured in a multi-TRP configuration UE. For example, in the single-TRP configuration UE, up to three CRS patterns per serving cell may be configured through the lte-CRS-PatternList1-r16 parameter. For another example, a CRS may be configured for each TRP in the multi-TRP configuration UE. That is, a CRS pattern for TRP1 may be configured through the lte-CRS-PatternList1-r16 parameter, and a CRS pattern for TRP2 may be configured through the lte-CRS-PatternList2-r16 parameter. On the other hand, in case that two TRPs are configured as described above, whether to apply both the CRS patterns of TRP1 and TRP2 to a specific physical downlink shared channel (PDSCH) or whether to apply only the CRS pattern for one TRP is determined through crs-RateMatch-PerCORESETPoolIndex-r16 parameter. When the crs-RateMatch-PerCORESETPoolIndex-r16 parameter is configured to be enabled, only one TRP CRS pattern is applied, and in other cases, both TRP CRS patterns are applied.
Table 17 shows the ServingCellConfig 1E including the CRS pattern, and Table 18 shows the RateMatchPatternLTE-CRS IE including at least one parameter for the CRS pattern.
In the following, a QCL priority determination operation for the PDCCH will be described in detail.
The UE may select a specific control resource set according to the QCL priority determination operation and monitor control resource sets having the same QCL-TypeD characteristics as the corresponding control resource set, in case that the UE operates with carrier aggregation within a single cell or band and a plurality of control resource sets existing within an activated bandwidth part within a single or multiple cells have the same or different QCL-TypeD characteristics in a specific PDCCH monitoring interval and overlap each other in time. That is, when a plurality of control resource sets overlap in time, only one QCL-TypeD characteristic can be received. In this case, the criteria for determining the QCL priority may be as follows.
As described above, the next criterion is applied in case that each of the above criteria is not satisfied. For example, in case that control resource sets overlap in time in a specific PDCCH monitoring duration, if all control resource sets are not connected to a common search space but connected to a UE-specific search period, that is, if criteria 1 is not satisfied, the UE may omit the application of criteria 1 and apply criteria 2.
In case of selecting a control resource set based on the above criteria, the UE may additionally consider the following two items for QCL information configured to the control resource set. First, if control resource set 1 has CSI-RS 1 as a reference signal having a QCL-TypeD relationship, and a reference signal that this CSI-RS 1 has a QCL-TypeD relationship is SSB 1, and in case that a reference signal that another control resource set 2 has a QCL-TypeD relationship is SSB 1, the UE may consider these two control resource sets 1 and 2 to have different QCL-TypeD characteristics. Second, if control resource set 1 has CSI-RS 1 configured in cell 1 as a reference signal having a QCL-TypeD relationship, and a reference signal that this CSI-RS 1 has a QCL-TypeD relationship is SSB 1, in case that control resource set 2 has CSI-RS 2 configured in cell 2 as a reference signal having a QCL-TypeD relationship and a reference signal that this CSI-RS 2 has a QCL-TypeD relationship is SSB 1, the UE may consider the two control resource sets to have the same QCL-TypeD characteristics.
With reference to
In case that the UE is configured to use only resource type 1 through higher layer signaling (13-05), some DCI for allocating a PDSCH to the UE includes frequency axis resource allocation information of ┌log2(NRBDL,BWP(NRBDL,BWP+1)/2┐bits. The conditions for this will be described later. The base station may configure a starting VRB 13-20 according thereto and the length 13-25 of a frequency axis resource allocation subsequent thereto.
In case that the UE is configured to use both the resource type 0 and the resource type 1 (13-10) through higher layer signaling, the part of DCI allocating the PDSCH to the corresponding UE includes the frequency axis resource allocation information including bits of a greater value 13-35 among a payload 13-15 for configuring the resource type 0 and a payload 13-20 and 13-25 for configuring the resource type 1. A condition therefor will be described below. In this case, one bit may be added to the most significant bit (MSB) of the frequency axis resource allocation information in the DCI, and in case that a value of the corresponding bit is ‘0’, the use of the resource type 0 may be indicated, and in case that the value of the corresponding bit is ‘1’, the use of the resource type 1 may be indicated.
Hereinafter, a time domain resource allocation method regarding a data channel in a next-generation mobile communication system (5G or NR system) will be described.
A base station may configure, to a UE, a table regarding time domain resource allocation information for a Physical Downlink Shared Channel (PDSCH) and a Physical Uplink Shared Channel (PUSCH), via higher layer signaling (for example, RRC signaling). For the PDSCH, a table including up to maxNrofDL-Allocations=16 entries may be configured, and for the PUSCH, a table including up to maxNrofUL-Allocations=16 entries may be configured. According to an embodiment, the time domain resource allocation information may include a PDCCH-to-PDSCH slot timing (corresponds to a time interval in a slot unit between a time point when the PDCCH is received and a time point when the PDSCH scheduled by the received PDCCH is transmitted, indicated by K0), a PDCCH-to-PUSCH slot timing (corresponds to a time interval in a slot unit between a time point when the PDCCH is received and a time point when the PUSCH scheduled by the received PDCCH is transmitted, indicated by K2), information about a location and length of a start symbol where the PDSCH or PUSCH is scheduled within a slot, and a mapping type of the PDSCH or PUSCH. For example, information such as Table 20 or 21 below may be transmitted from the base station to the UE.
The base station may notify the UE about one of entries in a table of the time domain resource allocation information, via L1 signaling (for example, DCI) (for example, indicated via a ‘time domain resource allocation’ field within DCI). The UE may obtain the time domain resource allocation information regarding the PDSCH or PUSCH, based on the DCI received from the base station.
With reference to
Definitions of respective fields in the MAC-CE and configurable values for respective fields are as follows.
Serving Cell ID (Serving cell identity): This field indicates the identity of the Serving Cell for which the MAC CE applies. The length of the field is 5 bits. If the indicated Serving Cell is configured as part of a simultaneousTCI-UpdateList1 or simultaneousTCI-UpdateList2 as specified in TS 38.331 [5], this MAC CE applies to all the Serving Cells configured in the set simultaneousTCI-UpdateList1 or simultaneousTCI-UpdateList2, respectively;
BWP ID (Bandwidth identity): This field indicates a DL BWP for which the MAC CE applies as the codepoint of the DCI bandwidth part indicator field as specified in TS 38.212 [9]. The length of the BWP ID field is 2 bits. This field is ignored if this MAC CE applies to a set of Serving Cells;
Ti (TCI state identity): If there is a TCI state with TCI-StateId i as specified in TS 38.331 [5], this field indicates the activation/deactivation status of the TCI state with TCI-StateId i, otherwise MAC entity shall ignore the Ti field. The Ti field is set to 1 to indicate that the TCI state with TCI-StateId i shall be activated and mapped to the codepoint of the DCI Transmission Configuration Indication field, as specified in TS 38.214 [7]. The Ti field is set to 0 to indicate that the TCI state with TCI-StateId i shall be deactivated and is not mapped to the codepoint of the DCI Transmission Configuration Indication field. The codepoint to which the TCI State is mapped is determined by its ordinal position among all the TCI States with Ti field set to 1, i.e. the first TCI State with Ti field set to 1 shall be mapped to the codepoint value 0, second TCI State with Ti field set to 1 shall be mapped to the codepoint value 1 and so on. The maximum number of activated TCI states is 8;
CORESET Pool ID (CORESET Pool ID identity): This field indicates that mapping between the activated TCI states and the codepoint of the DCI Transmission Configuration Indication set by field Ti is specific to the ControlResourceSetId configured with CORESET Pool ID as specified in TS 38.331 [5]. This field set to 1 indicates that this MAC CE shall be applied for the DL transmission scheduled by CORESET with the CORESET pool ID equal to 1, otherwise, this MAC CE shall be applied for the DL transmission scheduled by CORESET pool ID equal to 0. If the coresetPoolIndex is not configured for any CORESET, MAC entity shall ignore the CORESET Pool ID field in this MAC CE when receiving the MAC CE. If the Serving Cell in the MAC CE is configured in a cell list that contains more than one Serving Cell, the CORESET Pool ID field shall be ignored when receiving the MAC CE.
In the NR system, the UE may transmit uplink control information (UCI) to the base station through a physical uplink control channel (PUCCH). The control information may include at least one of HARQ-ACK indicating a success or failure of demodulation/decoding with respect to a transport block (TB) received by the UE through a PDSCH, a scheduling request (SR) by which the UE requests allocation of a resource from a PUSCH base station for uplink data transmission, and channel state information (CSI) for reporting a channel state of the UE.
PUCCH resources may be largely divided into a long PUCCH and a short PUCCH according to a length of an allocated symbol. In the NR system, the long PUCCH has a length of 4 or more symbols in a slot, and the short PUCCH has a length of 2 or less symbols in a slot.
To describe the long PUCCH in more detail, the long PUCCH may be used for improving an uplink cell coverage, and accordingly, may be transmitted by using a DFT-S-OFDM scheme, which is single subcarrier transmission, rather than by using OFDM transmission. The long PUCCH supports transmission formats, such as PUCCH format 1, PUCCH format 3, and PUCCH format 4, according to the number of bits of the control information which may be supported and whether or not multiplexing of the UE is supported through a Pre-DFT OCC support at an IFFT's front end.
First, PUCCH format 1 is a DFT-S-OFDM-based long PUCCH format capable of supporting up to 2 bits of control information and uses a frequency resource of up to 1 RB. The control information may include each or a combination of HARQ-ACK and SR. In PUCCH format 1, an OFDM symbol including a DeModulation Reference Signal (DMRS), which is a demodulation reference signal (or a reference signal), and an OFDM symbol including the UCI are repetitively configured.
For example, in case that the number of transmission symbols of PUCCH format 1 is eight, the eight symbols may include a DMRS symbol, a UCI symbol, a DMRS symbol, a UCI symbol, a DMRS symbol, a UCI symbol, a DMRS symbol, and a UCI symbol in a sequence of this stated order. The DMRS symbol may be spread by using an orthogonal code (or an orthogonal sequence or spreading code, wi(m)) on a time axis in a sequence corresponding to a duration of 1 RB on a frequency axis in one OFDM symbol and may be transmitted after IFFT is performed thereon.
The UCI symbol may be transmitted after the UE generates d (0) by performing BPSK modulation on the control information of 1 bit and QPSK modulation on the control information of 2 bits, scrambles the generated d (0) by multiplying the generated d (0) by a sequence corresponding to a duration of 1 RB on a frequency axis, spreads the scrambled sequence on a time axis by using an orthogonal code (or an orthogonal sequence or spreading code, wi(m)), and performs IFFT on the spread sequence.
The UE generates a sequence based on a group hopping or sequence hopping configuration configured from the base station through higher layer signaling and a configured ID and cyclic-shifts the generated sequence by using an initial cyclic shift (CS) value configured through a higher signal to generate a sequence corresponding to a length of 1 RB.
wi(m) is determined to be when a length NSF of the spreading code is given, and specifically, is given as in [Table 22] below. i represents an index of the spreading code itself, and m represents indices of elements of the spreading code. Here, numbers in [ ] described in [Table 22] denote ϕ(m). For example, when a length of the spreading code is 2, and an index of the configured spreading code is i=0, the spreading code wi(m) becomes
and accordingly, wi(m)=[11].
Next, PUCCH format 3 is a DFT-S-OFDM-based long PUCCH format capable of supporting the control information of more than 2 bits, and the number of used RBs may be configurable through a higher layer. The control information may include a combination or each of HARQ-ACK, SR, and CSI. In PUCCH format 3, DMRS symbol locations are presented in Table 23 below according to whether frequency hopping is performed in a slot and whether supplementary DMRS symbol is configured.
For example, in case that the number of transmission symbols of PUCCH format 3 is eight, a DMRS is transmitted at a first symbol and a fifth symbol, with 0 as the starting first symbol of the 8 symbols. Table 23 is applied to DMRS symbol locations of PUCCH format 4 in the same manner.
Next, PUCCH format 4 is a DFT-S-OFDM-based long PUCCH format capable of supporting the control information of more than 2 bits and uses a frequency resource of up to 1 RB. The control information may include a combination or each of HARQ-ACK, SR, and CSI. A difference of PUCCH format 4 from PUCCH format 3 is that in the case of PUCCH format 4, PUCCH format 4 of multiple UEs may be multiplexed in one RB. It is possible to multiplex PUCCH format 4 of a plurality of UEs by applying a Pre-DFT OCC to the control information at an IFFTs front end. However, the number of control information symbols which may be transmitted per UE may be reduced according to the number of multiplexed UEs. The number of UEs which may be multiplexed, that is, the number of different available OCCs may be 2 or 4, and the number of OCCs and an OCC index to be applied may be configured through a higher layer.
Next, a short PUCCH will be described. The short PUCCH may be transmitted from both of a downlink centric slot and an uplink centric slot and may generally be transmitted from a last symbol of a slot or an OFDM symbol at a back end (for example, the last OFDM symbol or the second to last OFDM symbol, or the last 2 OFDM symbols). Apparently, the short PUCCH may be transmitted from any location in the slot. Also, the short PUCCH may be transmitted by using one OFDM symbol or two OFDM symbols. The short PUCCH may be used to reduce a latency in comparison with the long PUCCH in a situation of a good uplink cell coverage and may be transmitted by using a CP-OFDM scheme.
The short PUCCH may support the transmission formats such as PUCCH format 0 and PUCCH format 2, according to the number of bits of the control information which may be supported. First, PUCCH format 0 is a short PUCCH format capable of supporting the control information of up to 2 bits and uses a frequency resource of up to 1 RB. The control information may include a combination or each of HARQ-ACK and SR. PUCCH format 0 has a structure in which a DMRS is not transmitted, and only a sequence mapped to 12 subcarriers on a frequency axis in one OFDM symbol is transmitted. The UE may generate a sequence based on a group hopping or sequence hopping configuration configured from the base station through a higher signal and configured IDs, may cyclic-shift the generated sequence by using a final CS value obtained by adding a different CS value to an indicated initial cyclic shift (CS) value according to ACK or NACK, may map the cyclic-shifted sequence to 12 subcarriers, and may transmit the mapped sequence.
For example, in case that HARQ-ACK is 1 bit, the UE may obtain the final CS value by adding 6 to the initial CS value in the case of ACK and may obtain the final CS value by adding 0 to the initial CS value in the case of NACK, as in Table 24. 0, which is the CS value for NACK, and 6, which is the CS value for ACK, are defined in the standards, and the UE may generate PUCCH format 0 according to the value defined in the standards and transmit 1-bit HARQ-ACK.
For example, in case that HARQ-ACK is two bits, the UE may add 0 to the initial CS value in the case of (NACK, NACK), may add 3 to the initial CS value in the case of (NACK, ACK), may add 6 to the initial CS value in the case of (ACK, ACK), and may add 9 to the initial CS value in the case of (ACK, NACK) as in Table 25. 0, which is the CS value for (NACK, NACK), 3, which is the CS value for (NACK, ACK), 6, which is the CS value for (ACK, ACK), and 9, which is the CS value for (ACK, NACK) may be defined in the standards, and the UE may generates PUCCH format 0 according to the value defined in the standards and transmit 2-bit HARQ-ACK. In case that the final CS value exceeds 12 by the CS value added to the initial CS value according to ACK or NACK, a length of the sequence is 12, and thus, modulo 12 may be applied to the final CS value.
Next, PUCCH format 2 is a short PUCCH format supporting the control information of more than 2 bits, and the number of used RBs may be configured through a higher layer. The control information may include a combination or each of HARQ-ACK, SR, and CSI. When an index of the first subcarrier is #0, in PUCCH format 2, locations of subcarriers transmitting a DMRS in one OFDM symbol may be fixed to subcarriers having indexes of #1, #4, #7, and #10. The control information may be mapped to remaining subcarriers except for the subcarrier in which the DMRS is located after a modulation process after channel encoding.
In summary, with respect to each PUCCH format described above, configurable values and their ranges may be summarized as in Table 26 below. In case that it is not needed to configure a value, N.A. is described, in Table 26 below.
Meanwhile, for the uplink coverage improvement, multi-slot repetition may be supported for PUCCH formats 1, 3, and 4, and PUCCH repetition may be configured for each PUCCH format. The UE may perform repetitive transmission with respect to a PUCCH including UCI corresponding to the number of slots configured through nrofSlots, which is higher layer signaling. With respect to the PUCCH repetitive transmission, PUCCH transmission of each slot may be performed by using the same number of consecutive symbols, and the corresponding number of consecutive symbols may be configured through nrofSymbols in PUCCH format 1, PUCCH format 3, or PUCCH format 4, which is higher layer signaling. With respect to the PUCCH repetitive transmission, the PUCCH transmission of each slot may be performed by using the same start symbol, and the corresponding start symbol may be configured through startingSymbolIndex in PUCCH format 1, PUCCH format 3, or PUCCH format 4, which is higher layer signaling. With respect to the PUCCH repetitive transmission, a single piece of PUCCH-spatialRelationlInfo may be configured with respect to a single PUCCH resource. With respect to the PUCCH repetitive transmission, when the UE is configured to perform frequency hopping in PUCCH transmission in different slots, the UE may perform frequency hopping in a slot unit. Also, when the UE is configured to perform frequency hopping in PUCCH transmission in different slots, the UE may start PUCCH transmission from a first PRB index configured through starting PRB which is higher layer signaling in an even numberth slot and may start PUCCH transmission from a second PRB index configured through secondHopPRB which is higher layer signaling in an odd numberth slot. Additionally, when the UE is configured to perform frequency hopping in PUCCH transmission in different slots, an index of a slot in which the UE is indicated to perform first PUCCH transmission is 0, and during the total number of times of configured PUCCH repetitive transmission, a value of the number of times of PUCCH repetitive transmission value may increase regardless of the PUCCH transmission in each slot. When the UE is configured to perform frequency hopping in PUCCH transmission in different slots, the UE may expect that frequency hopping is configured in a slot during PUCCH transmission. When the UE is not configured to perform frequency hopping in PUCCH transmission in different slots and is configured to perform frequency hopping in a slot, the first and second PRB indexes may be applied in the slot in the same manner. When the number of uplink symbols capable of PUCCH transmission is less than nrofSymbols configured through higher layer signaling, the UE may not transmit a PUCCH. Even when the UE has failed to transmit a PUCCH for a certain reason in a predetermined slot during the PUCCH repetitive transmission, the UE may increase the number of times of PUCCH repetitive transmission.
Next, PUCCH resource configuration of the base station or UE is described. The base station may be capable of configuring, for a predetermined UE, a PUCCH resource for each BWP via a higher layer. The PUCCH resource configuration may be the same as in Table 27 below.
According to Table 27, one or multiple PUCCH resource sets may be configured in a PUCCH resource configuration for a predetermined BWP, and a maximum payload value for UCI transmission may be configured in some of PUCCH resource sets. One or multiple PUCCH resources may be included in each PUCCH resource set, and each PUCCH resource may be included in one of the PUCCH formats described above.
With respect to the PUCCH resource sets, the first PUCCH resource set may have a maximum payload value that is fixed to 2 bits. Accordingly, the corresponding value may not be additionally configured through a higher layer, etc. In case that the remaining PUCCH resource sets are configured, an index of the corresponding PUCCH resource sets may be configured in an ascending order according to maximum payload values, and the maximum payload value may not be configured in the last PUCCH resource set. A higher layer configuration with respect to the PUCCH resource sets may be the same as Table 28 below.
In a resourceList parameter of Table 28, ID of the PUCCH resources included in the PUCCH resource sets may be included.
During an initial connection or in case that a PUCCH resource set is not configured, a PUCCH resource set composed of a plurality of cell-specific PUCCH resources in an initial BWP as shown in Table 29 below may be used. A PUCCH resource in the PUCCH resource set, the PUCCH resource being to be used for the initial connection, may be indicated through SIB1.
The maximum payload of each PUCCH resource included in the PUCCH resource sets may be 2 bits in the case of PUCCH format 0 or 1, and may be determined according to a symbol length, the number of PRBs, and a maximum code rate, in the case of the remaining formats. The symbol length and number of PRBs may be configured for each PUCCH resource, and the maximum code rate may be configured for each PUCCH format.
Next, PUCCH resource selection for UCI transmission is described. In the case of SR transmission, a PUCCH resource with respect to the SR corresponding to schedulingRequestID may be configured through a higher layer as in Table 30 below. The PUCCH resource may be a resource included in PUCCH format 0 or PUCCH format 1.
A transmission period and an offset of the configured PUCCH resource may be configured through a perodicityAndOffset of Table 30. In case that there is uplink data to be transmitted by the UE at a time point corresponding to the configured period and offset, the corresponding PUCCH resource may be transmitted, and in case that there is not uplink data to be transmitted by the UE at the time point corresponding to the configured period and offset, the corresponding PUCCH resource may not be transmitted.
In the case of CSI transmission, a PUCCH resource to transmit a periodic CSI report or a semi-persistent CSI report through PUCCH may be configured in a pucch-CSI-ResourceList parameter as in Table 31 below. The pucch-CSI-ResourceList parameter may include a list of PUCCH resources for each BWP with respect to a cell or a CC to transmit the corresponding CSI report. The PUCCH resource may be a resource included in PUCCH format 2, PUCCH format 3, or PUCCH format 4. A transmission period and offset of the PUCCH resource may be configured through reportSlotConfig of Table 31.
In the case of HARQ-ACK transmission, a resource set of PUCCH resources to be transmitted may be selected first according to a payload of UCI including the corresponding HARQ-ACK. That is, a PUCCH resource set having a minimum payload that is not less than a UCI payload may be selected. Next, a PUCCH resource in the PUCCH resource set may be selected through a PUCCH resource indicator (PRI) in DCI scheduling a TB corresponding to the corresponding HARQ-ACK, and the PRI may be a PUCCH resource indicator explicitly shown in Table 6 or Table 7. A relationship between the PRI and the PUCCH resource selected from the PUCCH resource set may be the same as in Table 32 below.
When the number of PUCCH resources selected in the PUCCH resource set is greater than 8, the PUCCH resource may be selected by the following equation.
In Equation 3, rPUCCH indicates an index of the PUCCH resource selected in the PUCCH resource set, RPUCCH indicates the number of PUCCH resources included in the PUCCH resource set, ΔPRI indicates a PRI value, NCCE,p indicates the total number of CCEs of CORESET p in which received DCI is included, and NCCE,p indicates a first CCE index with respect to the received DCI.
A time point at which the corresponding PUCCH resource is transmitted is after a K1 slot from TB transmission corresponding to the corresponding HARQ-ACK. A candidate of the K1 value may be set through a higher layer, and in more detail, may be set in a dl-DataToUL-ACK parameter in PUCCH-Config explicitly shown in Table 27. One K1 value from among these candidates may be selected by a PDSCH-to-HARQ feedback timing indicator in the DCI scheduling the TB, and this value may be a value explicitly shown in Table 5 or Table 6. A unit of the K1 value may be a slot unit or a sub-slot unit. Here, the sub-slot is a unit having a less length than the slot, and a sub-slot may include one or more symbols.
Next, a case in which two or more PUCCH resources are located in one slot is described. When the UE is capable of transmitting the UCI through one or more PUCCH resources in one slot or sub-slot, and the UCI is transmitted through two PUCCH resources in one slot/sub-slot, i) each PUCCH resource may not overlap each other in a symbol unit, and ii) at least one PUCCH resource may be a short PUCCH. Meanwhile, the UE may not expect to transmit a plurality of PUCCH resources for HARQ-ACK transmission in one slot.
Next, an uplink transmission beam configuration to be used for PUCCH transmission is described. When the UE does not have a dedicated PUCCH resource configuration, a PUCCH resource set may be provided through pucch-ResourceCommon which is higher layer signaling, and in this case, the beam configuration for the PUCCH transmission may be in accordance with a beam configuration used by PUSCH transmission scheduled through random access response (RAR) UL grant. When the UE has a dedicated PUCCH resource configuration, the beam configuration with respect to the PUCCH transmission may be provided through pucch-spatialRelationInfoID which is higher signaling indicated in Table 27. When the UE is configured with one pucch-spatialRelationInfoID, the beam configuration for the PUCCH transmission of the UE may be provided through one pucch-spatialRelationInfoID. When the UE is configured with a plurality of pucch-spatialRelationInfoIDs, the UE may be indicated to activate one pucch-spatialRelationInfoID from among the plurality of pucch-spatialRelationInfoIDs through an MAC control element (CE). The UE may be configured with maximum 8 pucch-spatialRelationInfoIDs through higher signaling and may be indicated to activate only one pucch-spatialRelationInfoID from among the 8 pucch-spatialRelationInfoIDs. In case that the UE is indicated to activate a random pucch-spatialRelationInfoID through the MAC CE, the UE may apply activation of the pucch-spatialRelationInfoID through the MAC CE from a slot first occurring after a slot of 3Nslotsubframe,μ from a slot transmitting HARQ-ACK with respect to a PDSCH transmitting the MAC CE containing activation information with respect to pucch-spatialRelationInfoID. μ denotes numerology applied to the PUCCH transmission, and Nslotsubframe,μ denotes the number of slots per subframe in the given numerology. A higher layer constitution with respect to pucch-spatialRelationInfo may be the same as Table 33 below.
According to the Table 33, one reference signal configuration may exist in a predetermined pucch-spatialRelationInfo configuration, and corresponding referenceSignal may be ssb-Index indicating a predetermined SS/PBCH, csi-RS-Index indicating a predetermined CSI-RS, or srs indicating a predetermined SRS. When referenceSignal is configured as ssb-Index, the UE may configure a beam used for receiving an SS/PBCH from among SSs/PBCHs in the same serving cell, the SS/PBCH corresponding to ssb_Index, as a beam for the PUCCH transmission, or when servingCellID is provided, the UE may configure a beam used for receiving an SS/PBCH from among SSs/PBCHs in a cell indicated by servingCellID, the SS/PBCH corresponding to ssb_Index, as a beam for the PUCCH transmission. When referenceSignal is configured as csi-RS-Index, the UE may configure a beam used for receiving a CSI-RS from among CSI-RSs in the same serving cell, the CSI-RS corresponding to csi-RS-Index, as a beam for the PUCCH transmission, or when servingCellID is provided, the UE may configure a beam used for receiving a CSI-RS from among CSI-RSs in a cell indicated by servingCellID, the CSI-RS corresponding to csi-RS-Index, as a beam for the PUCCH transmission. When referenceSignal is configured as srs, the UE may configure a transmission beam used for transmitting an SRS corresponding to a resource index provided through a higher signaling resource in the same serving cell and/or an activated uplink BWP, as a beam for the PUCCH transmission, or when servingCellID and/or uplinkBWP are/is provided, the UE may configure a transmission beam used for transmitting an SRS corresponding to a resource index provided through a higher signaling resource in a cell indicated by servingCellID and/or uplinkBWP and/or an uplink BWP, as a beam for the PUCCH transmission. There may be one pucch-PathlossReferenceRS-ID configuration in a predetermined pucch-spatialRelationInfo configuration. PUCCH-PathlossReferenceRS of Table 34 may be mapped with pucch-PathlossReferenceRS-ID of Table 33, and maximum 4 configurations are possible through pathlossReferenceRSs in higher signaling PUCCH-Powercontrol in Table 34. When PUCCH-PathlossReferenceRS is connected with the SS/PBCH through higher signaling referenceSignal, ssb-Index may be configured, and when PUCCH-PathlossReferenceRS is connected with the CSI-RS, csi-RS-Index may be configured.
In Rel-15, if the UE is configured with a plurality of pucch-spatialRelationInfoID, the UE may receive a MAC CE for activation of a spatial relation for each PUCCH resource, thereby determining a spatial relation of a PUCCH resource. However, such a method has a disadvantage of requiring excessive signaling overheads to activate the spatial relation of multiple PUCCH resources. Therefore, in Rel-16, a new MAC CE for adding a PUCCH resource group and activating a spatial relation in units of PUCCH resource groups has been introduced. For the PUCCH resource groups, up to 4 PUCCH resource groups may be configured via resourceGroupToAddModList of Table 27, and for each PUCCH resource group, multiple PUCCH resource IDs in one PUCCH resource group may be configured as a list as shown below in Table 35.
In Rel-16, the base station may configure each PUCCH resource group for the terminal via resourceGroupToAddModList in Table 27 and the higher layer configuration of Table 35, and may constitute a MAC CE for simultaneous activation of spatial relations of all PUCCH resources in one PUCCH resource group.
With reference to an example in
Next, an uplink channel estimation method using the Sounding Reference Signal (SRS) transmission of the UE is described. A base station may configure at least one SRS configuration for each UL BWP to deliver configuration information for SRS transmission to the UE, and may also configure at least one SRS resource set for each SRS configuration. For example, the base station and UE may transmit and receive higher signaling information as follows to deliver information about the SRS resource set.
The UE may understand that an SRS resource included in an SRS resource index set referenced by an SRS resource set conforms to information configured in the SRS resource set.
The base station and UE may transmit and/or receive higher layer signaling information in order to deliver individual configuration information for the SRS resource. As an example, the individual configuration information for the SRS resource may include time-frequency axis mapping information within a slot of the SRS resource, which may include information about frequency hopping within a slot or between slots of the SRS resource. The individual configuration information for the SRS resource may also include a time axis transmission configuration of the SRS resource, and may be configured to be one of ‘periodic’, ‘semi-persistent’, and ‘aperiodic’. This may be limited to having the time axis transmission configuration, such as the SRS resource set including the SRS resource. In case that the time axis transmission configuration of the SRS resource is configured to be ‘periodic’ or ‘semi-persistent’, an additional SRS resource transmission period and slot offset (e.g., periodicity AndOffset) may be included in the time axis transmission configuration.
The base station may activate, deactivate, or trigger SRS transmission to the UE via L1 signaling (e.g., DCI) or higher layer signaling including MAC CE signaling or RRC signaling. For example, the base station may activate or deactivate periodic SRS transmission for the UE via higher layer signaling. The base station may indicate to activate an SRS resource set in which resourceType is configured to be periodic via higher layer signaling, and the UE may transmit an SRS resource referenced by the activated SRS resource set. Time-frequency axis resource mapping within a slot of the transmitted SRS resource conforms to resource mapping information configured in the SRS resource, and slot mapping including a transmission period and slot offset conforms to periodicityAndOffset configured in the SRS resource. Also, a spatial domain transmission filter applied to the transmitted SRS resource may refer to spatial relation info configured in the SRS resource, or may refer to associated CSI-RS information configured in the SRS resource set including the SRS resource. The UE may transmit the SRS resource in a UL BWP activated for the periodic SRS resource activated via higher layer signaling.
For example, the base station may activate or deactivate semi-persistent SRS transmission for the UE via higher layer signaling. The base station may indicate to activate an SRS resource set via MAC CE signaling, and the UE may transmit an SRS resource referenced by the activated SRS resource set. The SRS resource set activated via MAC CE signaling may be limited to the SRS resource set in which resourceType is configured to be semi-persistent. Time-frequency axis resource mapping within a slot of the transmitted SRS resource conforms to resource mapping information configured in the SRS resource, and slot mapping including a transmission period and slot offset conforms to periodicity AndOffset configured in the SRS resource. Also, a spatial domain transmission filter applied to the transmitted SRS resource may refer to spatial relation info configured in the SRS resource, or may refer to associated CSI-RS information configured in the SRS resource set including the SRS resource. In case that a spatial relation info is configured in the SRS resource, instead of conforming to the same, the spatial domain transmission filter may be determined by referring to configuration information about spatial relation info delivered via MAC CE signaling for activation of semi-persistent SRS transmission. The UE may transmit the SRS resource in a UL BWP activated for the semi-persistent SRS resource activated via higher layer signaling.
For example, the base station may trigger aperiodic SRS transmission to the UE via DCI. The base station may indicate one of aperiodic SRS resource triggers (aperiodicSRS-ResourceTrigger) via an SRS request field of the DCI. The UE may understand that an SRS resource set has been triggered, the SRS resource set including an aperiodic SRS resource trigger indicated via the DCI in an aperiodic SRS resource trigger list in configuration information of the SRS resource set. The UE may transmit an SRS resource referenced by the triggered SRS resource set. Time-frequency axis resource mapping within a slot of the transmitted SRS resource conforms to resource mapping information configured in the SRS resource. In addition, slot mapping of the transmitted SRS resource may be determined via a slot offset between a PDCCH including the DCI and the SRS resource, which may refer to value(s) included in a slot offset set configured in the SRS resource set. Specifically, for the slot offset between the PDCCH including the DCI and the SRS resource, a value indicated by a time domain resource assignment field of the DCI from among offset value(s) included in the slot offset set configured in the SRS resource set may be applied. Also, a spatial domain transmission filter applied to the transmitted SRS resource may refer to spatial relation info configured in the SRS resource, or may refer to associated CSI-RS information configured in the SRS resource set including the SRS resource. The UE may transmit the SRS resource in a UL BWP activated for the aperiodic SRS resource triggered via the DCI.
In case that the base station triggers aperiodic SRS transmission to the UE via the DCI, in order for the UE to transmit an SRS by applying configuration information for the SRS resource, a minimum time interval between a PDCCH including the DCI triggering aperiodic SRS transmission and the transmitted SRS may be required. A time interval for SRS transmission of the UE may be defined to be the number of symbols between the last symbol of the PDCCH including the DCI triggering aperiodic SRS transmission and the first symbol to which a first transmitted SRS resource among the transmitted SRS resource(s) is mapped. The minimum time interval may be determined by referring to a PUSCH preparation procedure time required for the UE to prepare for PUSCH transmission. The minimum time interval may have a different value depending on a usage of the SRS resource set including the transmitted SRS resource. For example, the minimum time interval may be determined to be N2 symbols defined in consideration of UE processing capability according to the UE capability referring to the PUSCH preparation procedure time of the UE. Also, in case that a usage of the SRS resource set is configured to be ‘codebook’ or ‘antennaSwitching’ in consideration of the usage of the SRS resource set including the transmitted SRS resource, the minimum time interval may be determined to be N2 symbols. In case that the usage of the SRS resource set is configured to be ‘nonCodebook’ or ‘beamManagement’, the minimum time interval may be determined to be N2+14 symbols. In case that the time interval for aperiodic SRS transmission is greater than or equal to the minimum time interval, the UE may transmit an aperiodic SRS, and in case that the time interval for aperiodic SRS transmission is less than the minimum time interval, the UE may disregard the DCI triggering an aperiodic SRS.
The spatialRelationInfo configuration information in Table 36 above refers to one reference signal and applies beam information of the reference signal to a beam used for corresponding SRS transmission. For example, the configuration of spatialRelationInfo may include information as shown below in Table 37.
With reference to the configuration of spatialRelationInfo, an SS/PBCH block index, a CSI-RS index, and/or an SRS index may be configured as an index of a reference signal to be referenced in order to use beam information of a specific reference signal. Higher signaling referenceSignal may be referenced as configuration information indicating a reference signal's beam information of which is to be referenced for corresponding SRS transmission, ssb-Index may be referenced as an SS/PBCH block index, csi-RS-Index may be referenced as a CSI-RS index, and srs may be referenced as an SRS index, respectively. If a value of higher signaling referenceSignal is configured to be ssb-Index, the UE may apply, as a transmission beam of the corresponding SRS transmission, a reception beam used when receiving an SS/PBCH block corresponding to ssb-Index. If the value of higher signaling referenceSignal is configured to be ‘csi-RS-Index’, the UE may apply, as a transmission beam of the SRS transmission, a reception beam used when receiving a CSI-RS corresponding to csi-RS-Index. If the value of higher signaling referenceSignal is configured to be srs, the UE may apply, as a transmission beam of the SRS transmission, a transmission beam used when transmitting an SRS corresponding to srs.
Next, the scheduling scheme of PUSCH transmission will be described. The PUSCH transmission may be dynamically scheduled by a UL grant in DCI or may be operated by configured grant Type 1 or Type 2. Dynamic scheduling indication for PUSCH transmission is possible by DCI format 0_0 or 0_1.
For configured grant Type 1 PUSCH transmission, the UL grant in DCI may not be received, and configuration may be performed semi-statically via reception of configuredGrantConfig including rrc-ConfiguredUplinkGrant shown below in Table 38 via higher signaling. Configured grant Type 2 PUSCH transmission may be semi-persistently scheduled by the UL grant in DCI after reception of configuredGrantConfig that does not include rrc-ConfiguredUplinkGrant of Table 38 via higher signaling. In case that PUSCH transmission is operated by the configured grant, parameters applied to PUSCH transmission are applied via configuredGrantConfig that is higher signaling shown below in Table 38, except for dataScramblingIdentityPUSCH, txConfig, codebookSubset, maxRank, and scaling of UCI-OnPUSCH provided via pusch-Config that is higher signaling shown below in Table 39. If the UE is provided with transformPrecoder in configuredGrantConfig which is higher signaling in Table 38, the UE applies tp-pi2BPSK in pusch-Config of Table 39 to PUSCH transmission operated by the configured grant.
Next, the PUSCH transmission method will be described. The DMRS antenna port for PUSCH transmission is the same as an antenna port for SRS transmission. PUSCH transmission may conform to each of a codebook-based transmission method and a non-codebook-based transmission method, depending on whether a value of txConfig in pusch-Config of Table 39, which is higher signaling, corresponds to ‘codebook’ or ‘nonCodebook’.
As described above, PUSCH transmission may be dynamically scheduled via DCI format 0_0 or 0_1, and may be semi-statically configured by a configured grant. In case the UE is indicated with scheduling for PUSCH transmission via DCI format 0_0, the UE performs beam configuration for PUSCH transmission by using pucch-spatialRelationInfoID corresponding to a UE-specific PUCCH resource which corresponds to a minimum ID within an activated UL BWP in a serving cell. In this case, the PUSCH transmission is based on a single antenna port. The UE does not expect scheduling for PUSCH transmission via DCI format 0_0, within a BWP in which a PUCCH resource including pucch-spatialRelationInfo is not configured. If the UE is not configured with txConfig in pusch-Config of Table 39, the UE does not expect to be scheduled via DCI format 0_1.
Next, codebook-based PUSCH transmission will be described. The codebook-based PUSCH transmission may be dynamically scheduled via DCI format 0_0 or 0_1 and may operate semi-statically by a configured grant. If a codebook-based PUSCH is dynamically scheduled by DCI format 0_1 or is configured semi-statically by a configured grant, the UE determines a precoder for PUSCH transmission, based on an SRS resource indicator (SRI), a transmission precoding matrix indicator (TPMI), and a transmission rank (the number of PUSCH transmission layers).
In this case, the SRI may be given to the UE via an SRS resource indicator field, in DCI or may be configured via srs-ResourceIndicator that is higher signaling. The UE may be configured, during codebook-based PUSCH transmission, with at least one SRS resource and configured with up to two SRS resources. In case that the UE is provided with the SRI via DCI, for an SRS resource indicated by the corresponding SRI, an SRS resource corresponding to the SRI may be referenced from among SRS resources transmitted before a PDCCH including the corresponding SRI. Also, the TPMI and transmission rank may be given or configured via a field of precoding information and number of layers, in DCI or may be configured via precodingAndNumberOfLayers that is higher signaling. The TPMI is used to indicate a precoder applied to PUSCH transmission. If the UE is configured with one SRS resource, the TPMI is used to indicate a precoder to be applied in the configured one SRS resource. If the UE is configured with multiple SRS resources, the TPMI is used to indicate a precoder to be applied in the SRS resource indicated via the SRI.
A precoder to be used for PUSCH transmission is selected from a UL codebook having the same number of antenna ports as a value of nrofSRS-Ports in SRS-Config which is higher signaling. In codebook-based PUSCH transmission, the UE determines a codebook subset, based on codebookSubset in pusch-Config, which is higher signaling, and the TPMI. codebookSubset in pusch-Config which is higher signaling may be configured to be one of ‘fullyAndPartialAndNonCoherent’, ‘partialAndNonCoherent’, or ‘nonCoherent’, based on UE capability reported to the base station by the UE. If the UE has reported ‘partialAndNonCoherent’ as UE capability, the UE does not expect that a value of codebookSubset which is higher signaling is configured to be ‘fullyAndPartialAndNonCoherent’. Also, if the UE has reported ‘nonCoherent’ as UE capability, the UE expects the value of codebookSubset, which is higher signaling, to be configured to neither ‘fullyAndPartialAndNonCoherent’ nor ‘partialAndNonCoherent’. In case that nrofSRS-Ports in SRS-ResourceSet which is higher signaling indicates two SRS antenna ports, the UE does not expect that the value of codebookSubset which is higher signaling is configured to be ‘partialAndNonCoherent’.
The UE may be configured with one SRS resource set, in which a value of usage in SRS-ResourceSet that is higher signaling is configured to be ‘codebook’, and one SRS resource in the corresponding SRS resource set may be indicated via the SRI. If multiple SRS resources are configured in the SRS resource set in which the usage value in SRS-ResourceSet that is higher signaling is configured to be ‘codebook’, the UE expects that the value of nrofSRS-Ports in SRS-Resource that is higher signaling is configured to be the same for all SRS resources.
The UE transmits one or multiple SRS resources included in the SRS resource set, in which the value of usage is configured to be ‘codebook’, to the base station according to higher signaling, and the base station selects one of the SRS resources transmitted by the UE and indicates the UE to perform PUSCH transmission using transmission beam information of the corresponding SRS resource. In this case, in codebook-based PUSCH transmission, the SRI is used as information for selecting of an index of one SRS resource and is included in the DCI. In addition, the base station includes, to the DCI, information indicating the rank and TPMI to be used for PUSCH transmission by the UE. The UE uses the SRS resource indicated by the SRI to perform PUSCH transmission by applying the precoder indicated by the TPMI and rank, which has been indicated based on a transmission beam of the SRS resource.
Next, non-codebook-based PUSCH transmission will be described. The non-codebook-based PUSCH transmission may be dynamically scheduled via DCI format 0_0 or 0_1 and may operate semi-statically by a configured grant. In case that at least one SRS resource is configured in an SRS resource set, in which the value of usage in SRS-ResourceSet that is higher signaling is configured to be ‘nonCodebook’, the UE may be scheduled for non-codebook-based PUSCH transmission via DCI format 0_1.
For the SRS resource set in which the value of usage in SRS-ResourceSet that is higher signaling is configured to be ‘nonCodebook’, the UE may be configured with one connected non-zero power (NZP) CSI-RS resource. The UE may perform calculation on a precoder for SRS transmission via measurement for the NZP CSI-RS resource connected to the SRS resource set. If a difference between a last reception symbol of an aperiodic NZP CSI-RS resource connected to the SRS resource set and a first symbol of aperiodic SRS transmission in the UE is less than 42 symbols, the UE does not expect information about the precoder for SRS transmission to be updated.
In case that a value of resourceType in SRS-ResourceSet that is higher signaling is configured to be ‘aperiodic’, the connected NZP CSI-RS may be indicated via a field, SRS request, in DCI format 0_1 or 1_1. In this case, if the connected NZP CSI-RS resource is an aperiodic NZP CSI-RS resource, the presence of the connected NZP CSI-RS in case that a value of the field, SRS request, in DCI format 0_1 or 1_1 is not ‘00’ is indicated. In this case, the corresponding DCI should indicate neither a cross carrier nor cross BWP scheduling. Also, if the value of SRS request indicates the presence of the NZP CSI-RS, the corresponding NZP CSI-RS is located at a slot in which a PDCCH including the SRS request field has been transmitted. In this case, TCI states configured in scheduled subcarriers are not configured to be QCL-TypeD.
If a periodic or semi-persistent SRS resource set is configured, the connected NZP CSI-RS may be indicated via associatedCSI-RS in SRS-ResourceSet that is higher signaling. For non-codebook-based transmission, the UE does not expect that spatialRelationInfo, which is higher signaling for the SRS resource, and associatedCSI-RS in SRS-ResourceSet that is higher signaling are configured together.
In case that multiple SRS resources are configured, the UE may determine the precoder and transmission rank to be applied to PUSCH transmission, based on the SRI indicated by the base station. In this case, the SRI may be indicated via the field, SRS resource indicator, in DCI or may be configured via srs-ResourceIndicator that is higher signaling. As with the aforementioned codebook-based PUSCH transmission, in case that the UE is provided with the SRI via the DCI, the SRS resource indicated by the corresponding SRI refers to an SRS resource corresponding to the SRI from among SRS resources transmitted before the PDCCH including the SRI. The UE may use one or multiple SRS resources for SRS transmission, and the maximum number of SRS resources simultaneously transmittable in the same symbol within one SRS resource set may be determined by UE capability reported to the base station by the UE. In this case, the SRS resources that the UE simultaneously transmits occupy the same RB. The UE configures one SRS port for each SRS resource. Only one SRS resource set, in which the value of usage in SRS-ResourceSet that is higher signaling is configured to be ‘nonCodebook’, may be configured, and up to 4 SRS resources for the non-codebook-based PUSCH transmission may be configured.
The base station transmits one NZP CSI-RS connected to the SRS resource set to the UE, and the UE calculates, based on a result of measurement during reception of the NZP CSI-RS, the precoder to be used during transmission of one or multiple SRS resources in the corresponding SRS resource set. The UE applies the calculated precoder when transmitting, to the base station, one or multiple SRS resources in the SRS resource set in which usage is configured to be ‘nonCodebook’, and the base station may select one or multiple SRS resources from among the received one or multiple SRS resources. In this case, in non-codebook-based PUSCH transmission, the SRI indicates an index capable of expressing one SRS resource or a combination of multiple SRS resources, and the SRI may be included in the DCI. In this case, the number of SRS resources indicated by the SRI transmitted by the base station may be the number of PUSCH transmission layers, and the UE may transmit the PUSCH by applying, to each layer, the precoder applied to SRS resource transmission.
Next, PUSCH preparation procedure time will be described. In case that the base station uses DCI format 0_0, 0_1, or 0_2 to schedule the UE to transmit a PUSCH, the UE may require a PUSCH preparation procedure time for transmitting the PUSCH by applying a transmission method indicated via DCI (a method for transmission precoding for an SRS resource, the number of transmission layers, and/or s spatial domain transmission filter). In NR, the PUSCH preparation procedure time is defined in consideration of the preparation time. The PUSCH preparation procedure time of the UE may conform to Equation 4 below.
Each variable in Tproc,2 described using Equation 4 may have the following meaning.
N2: The number of symbols determined according to numerology u and UE processing capability 1 or 2 according to UE capability. In case that UE processing capability 1 is reported according to capability reporting of the UE, N2 may have values shown below in Table 40, and in case that UE processing capability 2 is reported and it is configured, via higher layer signaling, that UE processing capability 2 is available, N2 may have values shown below in Table 41.
μ: μ follows one of μDL and μUL, at which Tproc,2 has a greater value. μDZ indicates a numerology of a DL in which a PDCCH including DCI for PUSCH scheduling is transmitted, and μUL indicates a numerology of a UL in which a PUSCH is transmitted.
The base station and UE determine that the PUSCH preparation procedure time is insufficient when a first symbol of the PUSCH starts before a first UL symbol in which a CP starts after Tproc,2 from a last symbol of the PDCCH including the DCI for scheduling of the PUSCH, in consideration of time axis resource mapping information of the PUSCH scheduled via the DCI and a timing advance effect between the UL and the DL. Otherwise, the base station and UE determine that the PUSCH preparation procedure time is sufficient. Only in the case that the PUSCH preparation procedure time is sufficient, the UE transmits the PUSCH, and in case that the PUSCH preparation procedure time is insufficient, the UE may disregard the DCI for scheduling of the PUSCH.
Hereinafter, repeated transmission of uplink data channels in the 5G system will be described in detail. In the 5G system, repeated PUSCH transmission type A and repeated PUSCH transmission type B are supported as two types of the method for repeated transmission of a UL data channel. The UE may be configured with one of repeated PUSCH transmission type A or B via higher layer signaling.
As described above, a symbol length of a UL data channel and location of a start symbol are determined by a time domain resource allocation method within one slot, and the base station may notify the UE of the number of repeated transmissions via higher layer signaling (e.g., RRC signaling) or L1 signaling (e.g., DCI).
The UE may repeatedly transmit a UL data channel, which has the same length and start symbol as the configured length and start symbol of the UL data channel, in consecutive slots, based on the number of repeated transmissions received from the base station. In this case, in case that at least one symbol in symbols of the UL data channel configured for the UE or a slot configured for DL for the UE by the base station is configured for DL, the UE omits UL data channel transmission, but may count the number of repeated transmissions of the UL data channel.
and a symbol starting in the slot is given by mod (S+n·L,Nsymbslot). A slot in which n-th nominal repetition ends is given by
and a symbol ending in the slot is given by mod(S+ (n+1)·L−1,Nsymbslot. Here, n=0, numberofrepetitions-1, S is the configured start symbol of the UL data channel, and L indicates the configured symbol length of the UL data channel. Ks indicates a slot in which PUSCH transmission starts, and Nsymbslot indicates the number of symbols per slot.
The UE determines an invalid symbol for repeated PUSCH transmission type B. A symbol configured for DL by tdd-UL-DL-ConfigurationCommon or tdd-UL-DL-ConfigurationDedicated is determined as an invalid symbol for repeated PUSCH transmission type B. In addition, an invalid symbol may be configured by a higher layer parameter (e.g., InvalidSymbolPattern). A higher layer parameter (e.g., InvalidSymbolPattern) may provide a symbol-level bitmap over one slot or two slots so that an invalid symbol may be configured. 1 in the bitmap indicates an invalid symbol. In addition, a period and pattern of the bitmap may be configured via a higher layer parameter (e.g., periodicityAndPattern). If the higher layer parameter (e.g., InvalidSymbolPattern) is configured, and parameter InvalidSymbolPatternIndicator-ForDCIFormat0_1 or InvalidSymbolPatternIndicator-ForDCIFormat0_2 indicates 1, the UE may apply an invalid symbol pattern. If the parameter indicates 0, the UE does not apply the invalid symbol pattern. If the higher layer parameter (e.g., InvalidSymbolPattern) is configured, and parameter InvalidSymbolPatternIndicator-ForDCIFormat0_1 or InvalidSymbolPatternIndicator-ForDCIFormat0_2 is not configured, the UE applies the invalid symbol pattern
After an invalid symbol is determined, for each nominal repetition, the UE may consider symbols other than the invalid symbol to be valid symbols. If one or more valid symbols are included in each nominal repetition, the nominal repetition may include one or more actual repetitions. Here, respective actual repetitions include consecutive sets of valid symbols available for repeated PUSCH transmission type B within one slot.
For the UE, a start symbol S of a UL data channel may be configured to be 0, a length L of the UL data channel may be configured to be 14, and the number of repeated transmissions may be configured to be 16. In this case, nominal repetition is shown in 16 consecutive slots (1701). Then, the UE may determine, as an invalid symbol, a symbol configured to be a DL symbol in each nominal repetition (1701). The UE also determines, as invalid symbols, symbols configured to be 1 in an invalid symbol pattern 1702. In each nominal repetition, in case that valid symbols that are not invalid symbols include one or more consecutive symbols in one slot, actual repetition is configured and transmitted (1703).
Also, with respect to repeated PUSCH transmission, in NR Release 16, the following additional methods may be defined for UL grant-based PUSCH transmission and configured grant-based PUSCH transmission over slot boundaries.
Hereinafter, the frequency hopping of an uplink data channel (Physical Uplink Shared Channel (PUSCH)) in the 5G system will be described in detail.
In the 5G, as a frequency hopping method of a UL data channel, two methods may be supported for each repeated PUSCH transmission type. Repeated PUSCH transmission type A may support intra-slot frequency hopping and inter-slot frequency hopping, and repeated PUSCH transmission type B may support inter-repetition frequency hopping and inter-slot frequency hopping.
In the intra-slot frequency hopping method supported by repeated PUSCH transmission type A, the UE changes an allocated resource of the frequency domain by a configured frequency offset in two hops within one slot and performs transmission. In intra-slot frequency hopping, a starting RB of each hop may be expressed via Equation 5 below.
In Equation 5, i=0 and i=1 indicate a first hop and a second hop, respectively, and RBstart indicates a starting RB in a UL BWP and is calculated based on a frequency resource allocation method. RBoffset indicates a frequency offset between two hops via a higher-layer parameter. The number of symbols of the first hop may be indicated by └NsymbPUSCH,s/2┘, and the number of symbols of the second hop may be indicated by NsymbPUSCH,s−└symbPUSCH,s/2┘. NsymbPUSCH,s is a length of PUSCH transmission within one slot and is represented by the number of OFDM symbols.
Next, in the inter-slot frequency hopping method supported by repeated PUSCH transmission types A and B, the UE changes an allocated resource of the frequency domain by a configured frequency offset for each slot and performs transmission. In inter-slot frequency hopping, during nsμ slots, a starting RB may be expressed via Equation 6 below.
In Equation 6, nsμ indicates a current slot number in multi-slot PUSCH transmission, and RBstart indicates a starting RB in a UL BWP and is calculated based on the frequency resource allocation method. RBoffset indicates a frequency offset between two hops via a higher layer parameter.
The inter-repetition frequency hopping method supported by repeated PUSCH transmission type B includes performing transmission by moving resources allocated on the frequency domain as much as a configured frequency offset for one or multiple actual repetitions within each nominal repetition. RBstart(n), which is an index of a starting RB in the frequency domain for one or multiple actual repetitions within an n-th nominal repetition, may conform to Equation 7 below.
In Equation 7, n indicates an index of nominal repetition, and RB offset indicates an RB offset between two hops via a higher layer parameter.
In LTE and NR, the UE may perform a procedure of reporting, to the base station, capability supported by the UE while being connected to a serving base station. Hereinafter, such a procedure will be referred to as a UE capability report.
The base station may transmit, to the UE in a connected state, a UE capability enquiry message requesting a capability report. The UE capability request message may include a UE capability request for each radio access technology (RAT) type of the base station. The UE capability request for each RAT type may include supported frequency band combination information or the like. Also, in the case of the UE capability enquiry message, a plurality of UE capabilities for each RAT type may be requested via one RRC message container transmitted by the base station, or the base station may transmit, to the UE, the UE capability enquiry message including the UE capability request for each RAT type a plurality of times. In other words, the UE capability enquiry may be repeated a plurality of times in one message, and the UE may constitute a corresponding UE capability information message and report the same a plurality of times. In a next-generation mobile communication system, the UE capability may be requested for multi-RAT dual connectivity (MR-DC) as well as NR, LTE, and E-UTRA-NR dual connectivity (EN-DC). Also, the UE capability enquiry message is generally transmitted at an initial stage after the UE is connected to the base station, but may be requested in any condition upon necessity by the base station.
Upon receiving a UE capability report request from the base station, the UE constitutes UE capability according to band information and RAT type requested by the base station. A method by which the UE constitutes the UE capability in an NR system will now be described.
1. When the UE receives, from the base station, a list of LTE and/or NR bands as the UE capability request, the UE constitutes a band combination (BC) regarding EN-DC and NR stand-alone (SA). In other words, the UE constitutes candidate list of BCs regarding the EN-DC and NR SA, based on bands requested from the base station by FreqBandList. Priorities of the bands are in an order stated in FreqBandList.
2. When the base station has requested the UE capability report by setting a “eutra-nr-only” flag or a “eutra” flag, the UE may completely remove candidates regarding NR SA BC from the configured candidate list of BCs. Such an operation may be performed only when an LTE base station (eNB) requests “eutra” capability.
3. Then, the UE removes fallback BCs from the configured candidate list of BCs. Here, the fallback BC denotes a BC obtainable by removing a band corresponding to at least one SCell from an arbitrary BC, and this is possible because a BC before removing the band corresponding to the at least one SCell already covers the fallback BC. This operation is also applied to MR-DC, i.e., to LTE bands. The remaining BCs after this operation are a final candidate list of BCs.
4 The UE selects BCs to be reported by selecting, from the “final candidate list of BCs”, the BCs according to a requested RAT type. In this operation, the UE constitutes supportedBandCombinationList in a determined order. In other words, the UE constitutes UE capability and BCs to be reported according to an order of pre-configured rat-Type. (nr->eutra-nr->eutra). Also, featureSetCombination regarding the configured supportedBandCombinationList is constituted, and a list of “candidate feature set combinations” is constituted from the candidate list of BCs from which a list of fallback BCs (including capability of a same or lower level) is removed. The “candidate feature set combination” includes all feature set combinations regarding NR and EUTRA-NR BCs, and may be obtained from feature set combinations of UE-NR-Capabilities and UE-MRDC-Capabilities containers.
5. Further, when the requested rat Type is eutra-nr and affected, the featureSetCombinations are included both of the UE-MRDC-Capabilities and UE-NR-Capabilities containers. However, a feature set of NR only includes UE-NR-Capabilities.
After the UE capability is constituted, the UE delivers, to the base station, UE capability information message including the UE capability. Based on the UE capability received from the UE, the base station performs, on the UE, appropriate scheduling and transmission/reception management.
With reference to
Main functions of the NR SDAPs S25 and S70 may include some of the following functions:
Regarding the SDAP layer device, the UE may be configured with, by an RRC message, whether to use a header of the SDAP layer device or whether to use a function of the SDAP layer device for each PDCP layer device, for each bearer, or for each logical channel. In case that an SDAP header is configured, an NAS reflective QoS configuration 1-bit indicator and AS reflective QoS configuration 1-bit indicator of the SDAP header may indicate the UE to update or reconfigure mapping information between a QoS flow and a data radio bearer for UL and DL. The SDAP header may include QoS flow ID information indicating QoS. The QoS information may be used as data processing priority information, scheduling information, or the like for supporting a smooth service.
Main functions of the NR PDCP S30 or S65 may include some of the following functions:
In the above, a reordering function of the NR PDCP device may denote a function of reordering PDCP PDUs received from a lower layer, based on a PDCP sequence number (SN), and may include a function of delivering data to a higher layer in a reordered order. Alternatively, the reordering function of the NR PDCP device may include a function of immediately delivering the data without considering an order, a function of recording missing PDCP PDUs by reordering the order, a function of reporting a status regarding the missing PDCP PDUs to a transmitter, and a function of requesting to retransmit the missing PDCP PDUs.
The main function of the NR RLC S35 or S60 may include some of the following functions.
In the above, the in-sequence delivery function of the NR RLC device may denote a function of delivering RLC SDUs received from a lower layer, to a higher layer in order. The in-sequence delivery function of the NR RLC device may include a function of reassembling RLC SDUs segmented from an RLC SDU and delivering the RLC SDUs in case that the segmented RLC SDUs are received, a function of reordering received RLC PDUs on an RLC sequence number (SN) or PDCP sequence number (SN) basis, a function of recording missing RLC PDUs by reordering the order, a function of reporting a status of the missing RLC PDUs to a transmitter, and a function of requesting to retransmit the missing RLC PDUs. The in-sequence delivery function of the NR RLC device may include a function of delivering only RLC SDUs previous to a missing RLC SDU, to a higher layer in order, in case that the missing RLC SDU exists, or a function of delivering all RLC SDUs received before a timer is started, to a higher layer in order, even when a missing RLC SDU exists, when a certain timer is expired. Alternatively, the in-sequence delivery function of the NR RLC device may include a function of delivering all RLC SDUs currently received to the higher layer in order, when a certain timer is expired despite of a missing RLC SDU. Further, the RLC PDUs may be processed in order of reception (in order of arrival regardless of the order of sequence numbers) and the RLC PDUs may be delivered to the PDCP device out of order (out-of sequence delivery), and in case of segments, segments to be received to be later or stored in a buffer may be reconstituted into a whole RLC PDU and processed, the RLC PDU may be delivered to the PDCP device. The NR RLC layer may not have a concatenation function, and the concatenation function may be performed by the NR MAC layer or be replaced with a multiplexing function of the NR MAC layer.
In the above, the out-of-sequence delivery function of the NR RLC device denotes a function of delivering RLC SDUs received from a lower layer immediately to a higher layer regardless of order, and may include a function of reassembling and delivering segmented and received RLC SDUs in case that one RLC SDU is originally segmented into several RLC SDUs and received, and a function of recording missing RLC PDUs by storing RLC SN or PDCP SN of the received RLC PDUs and reordering the same.
The NR MAC S40 or S55 may be connected to multiple NR RLC layer devices constituted for a single UE, and main functions of the NR MAC may include at least some of the following functions:
The NR PHY layer S45 or S50 may channel-code and modulate higher layer data into OFDM symbols and transmit the OFDM symbols through a radio channel, or demodulate OFDM symbols received through a radio channel and channel-decode and deliver the OFDM symbols to a higher layer.
The radio protocol architecture may have various detailed structures depending on a carrier (or cell) operating scheme. For example, in case that the base station transmits data to the UE, based on a single carrier (or cell), the base station and UE use a protocol architecture having a single structure per layer, as indicated by S00. On the other hand, in case that the base station transmits data to the UE, based on carrier aggregation (CA) using multiple carriers in a single TRP, the base station and UE use a protocol architecture of having a single structure up to an RLC but multiplexing a PHY layer via an MAC layer, as in S10. As another example, in case that the base station transmits data to the UE, based on dual connectivity (DC) using multiple carriers in a multiple TRP, the base station and UE use a protocol architecture of having a single structure up to an RLC but multiplexing a PHY layer via an MAC layer, as in S20.
According to an embodiment of the disclosure, non-coherent joint transmission (NC-JT) may be used for the UE to receive a PDSCH from a plurality of TRPs.
Unlike an existing communication system, a 5G wireless communication system may support not only a service requiring a high data rate, but also both a service having a very short transmission latency and a service requiring high connection density. Cooperative communication (coordinated transmission) between respective cells, TRPs, and/or beams in a wireless communication network including a plurality of cells, transmission and reception points (TRPs), or beams may satisfy various service requirements by efficiently performing inter-cell, TRP, and/or beam interference control or by increasing strength of a signal received by the UE.
Joint transmission (JT) is one of representative transmission technologies for the cooperative communication, and is a technology for increasing the strength or throughput of signal received by the UE, by transmitting the signal to the UE via a plurality of different cells, TRPs, and/or beams. Here, characteristics of channels between the UE and each cell, TRP, and/or beam may largely vary, and in particular, non-coherent (NC)-joint transmission (JT) supporting non-coherent precoding between respective cells, TRPs and/or beams may require individual precoding, MCS, resource allocation, or TCI indication, according to channel characteristics for each link between the UE and each cell, TRP, and or beam.
The above-described NC-JT transmission may be applied to at least one of a downlink data channel (physical downlink shared channel (PDSCH)), a downlink control channel (physical downlink control channel (PDCCH)), an uplink data channel (physical uplink shared channel (PUSCH)), or an uplink control channel (physical uplink control channel (PUCCH)) . . . . During PDSCH transmission, transmission information, such as precoding, MCS, resource allocation, or TCI, is indicated by DL DCI, and for NC-JT transmission, the transmission information needs to be indicated independently for each cell, TRP, and/or beam. This is a main factor for increasing payload required for DL DCI transmission, and may adversely affect reception performance of a PDCCH transmitting DCI. Accordingly, it is necessary to carefully design tradeoff between DCI amount and control information reception performance for JT support of a PDSCH.
With reference to
With reference to
In case of C-JT, single piece of data (PDSCH) is transmitted from a TRP A N005 and a TRP B N010 to a UE N015, and a plurality of TRPs perform joint precoding. This may indicate that a DMRS is transmitted through same DMRS ports for the TRP A N005 and TRP B N010 to transmit a same PDSCH. For example, the TRP A N005 and TRP B N010 may each transmit the DMRS to the UE through a DMRS port A and a DMRS port B. In this case, the UE may receive one piece of DCI for receiving one PDSCH demodulated based on the DMRS transmitted through the DMRS ports A and B.
In
In case of NC-JT, a PDSCH is transmitted to a UE N035 for each cell, TRP, and/or beam, and individual precoding may be applied to each PDSCH. Each cell, TRP, and/or beam may transmit, to the UE, different PDSCHs or different PDSCH layers to improve throughput relative to single cell, TRP, and/or beam transmission. Also, each cell, TRP, and/or beam may repeatedly transmit the same PDSCH to the UE to improve reliability relative to the single cell, TRP, and/or beam transmission. For convenience of description, a cell, TRP, and/or beam will be collectively referred to as a TRP below.
Here, various radio resource allocations may be considered for the PDSCH transmission, for example, a case N040 where frequency and time resources used by a plurality of TRPs are all same, a case N045 where frequency and time resources used by a plurality of TRPs do not overlap, and a case N050 where frequency and time resources used by a plurality of TRPs partially overlap.
To support NC-JT, pieces of DCIs of various forms, structures, and relationships may be considered to simultaneously allocate a plurality of PDSCHs to one UE.
With reference to
A case #2 N105 is an example in which, while the different N−1 PDSCHs are transmitted from the additional N−1 TRPs (TRP #1 to TRP #N−1) except the serving TRP (TRP #0) used during the single PDSCH transmission, the pieces of control information (DCI) regarding the PDSCHs transmitted from the additional N−1 TRPs are each transmitted and each piece of DCI is dependent on the control information regarding the PDSCH transmitted from the serving TRP.
For example, the DCI #0 that is the control information regarding the PDSCH transmitted from the serving TRP (TRP #0) includes all information elements of a DCI format 1_0, a DCI format 1_1, and a DCI format 1_2, but shortened DCI (hereinafter, sDCI) (sDCI #0 to sDCI #N−2) that is control information regarding the PDSCHs transmitted from the cooperative TRPs (TRP #1 to TRP #N−1) may include some of the information elements of the DCI format 1_0, the DCI format 1_1, and the DCI format 1_2. Accordingly, because the sDCI transmitting the control information regarding the PDSCHs transmitted from the cooperative TRPs has a small payload compared to normal DCI (nDCI) transmitting the control information regarding the PDSCH transmitted from the serving TRP, it is possible for the sDCI to include reserved bits compared to the nDCI.
The above-described case #2 may have limited PDSCH control or degree of freedom of allocation according to content of the information elements included in the sDCI, but may have a low probability of an occurrence of a coverage difference for each piece of DCI because reception performance of the sDCI is superior compared to the nDCI.
A case #3 N110 is an example in which, while the different N−1 PDSCHs are transmitted from the additional N−1 TRPs (TRP #1 to TRP #N−1) except the serving TRP (TRP #0) used during the single PDSCH transmission, one piece of control information regarding the PDSCHs of the additional N−1 TRPs is transmitted and this DCI is dependent on the control information regarding the PDSCH transmitted from the serving TRP.
For example, the DCI #0 that is the control information regarding the PDSCH transmitted from the serving TRP (TRP #0) includes all information elements of the DCI format 1_0, the DCI format 1_1, and the DCI format 1-2, and for the control information regarding the PDSCHs transmitted from the cooperative TRPs (TRP #1 to TRP #N−1), it is possible to gather some of the information elements of the DCI format 1_0, the DCI format 1_1, and the DCI format 1_2 to one piece of ‘secondary’ DCI (sDCI) for transmission. For example, the sDCI may include at least one piece of information of the cooperative TRPs, from among frequency domain resource assignment, time domain resource assignment, and HARQ-related information, such as MSC. In addition, information not included in the sDCI, such as a bandwidth part (BWP) indicator or a carrier indicator, may follow the DCI (DCI #0, normal DCI, nDCI) of the serving TRP.
The case #3 N110 may have limited PDSCH control or degree of freedom of allocation according to content of the information elements included in the sDCI, but reception performance of the sDCI may be controlled and complexity of DCI blind decoding of the UE may be low compared to the case #1 N100 and case #2 N105.
A case #4 N115 is an example in which, while the different N−1 PDSCHs are transmitted from the additional N−1 TRPs (TRP #1 to TRP #N−1) except the serving TRP (TRP #0) used during the single PDSCH transmission, the control information regarding the PDSCHs transmitted from the additional N−1 TRPs is transmitted on a same DCI (long DCI) as the control information regarding the PDSCH transmitted from the serving TRP. In other words, the UE may obtain, via single DCI, the control information regarding the PDSCHs transmitted from the different TRPs (TRP #0 to TRP #N−1). In the case #4 N115, complexity of DCI blind decoding of the UE may not be high, but PDSCH control or a degree of freedom of allocation may be low, for example, the number of cooperative TRPs may be limited, according to long DCI payload limitation.
In the description and embodiments of the disclosure below, the sDCI may denote various types of auxiliary DCI, such as shortened DCI, secondary DCI, and normal DCI (the DCI format 1_0 to 1_1 described above) including PDSCH control information transmitted from a cooperative TRP, and unless a limitation is specifically stated, the corresponding description may be similarly applied to the various types of auxiliary DCI.
In the description and embodiments of the disclosure below, the case #1 N100, the case #2 N105, and the case #3 N110 using one or more pieces of DCI (PDCCHs) to support NC-JT may be distinguished as multiple PDCCH-based NC-JT, and the case #4 N115 using a single piece of DCI (PDCCH) to support NC-JT may be distinguished as single PDCCH-based NC-JT. In multiple PDCCH-based PDSCH transmission, a CORESET scheduling DCI of the serving TRP (TRP #0) and a CORESET scheduling DCI of the cooperative TRPs (TRP #1 to TRP #N−1) may be distinguished. To distinguish the CORESETs, a method for distinguishing the CORESETs via a higher layer indicator for each CORESET, a method for distinguishing the CORESETs via a beam configuration for each CORESET, or the like may be used. Also, in the single PDCCH-based NC-JT, instead of scheduling a plurality of PDSCHs by a single piece of DCI, a single PDSCH including a plurality of layers is scheduled, and the above-described plurality of layers may be transmitted from a plurality of TRPs. Here, a connection relationship between the layer and the TRP transmitting the corresponding layer may be indicated via a transmission configuration indicator (TCI) indication regarding the layer.
In embodiments of the disclosure, a “cooperative TRP” may be replaced by any one of various terms, such as “cooperative panel,” a “cooperative beam,” or the like, when actually applied.
In embodiments of the disclosure, the phrase “in case that NC-JT is applied” may be variously interpreted depending on a situation, for example, “in case that a UE simultaneously receives one or more PDSCHs from one BWP,” “in case that a UE simultaneously receives PDSCHs based on two or more transmission configuration indicator (TCI) indications from one BWP,” and “in case that a PDSCH received by a UE is associated with at least one DMRS port group,” but one expression is used for convenience of description.
In the disclosure, a radio protocol structure for NC-JT may be used in various ways according to a TRP deployment scenario. As an example, in case that there is no or small backhaul delay between cooperative TRPs, it is possible to use a structure based on MAC layer multiplexing similar to S10 in
The UE supporting C-JT/NC-JT may receive, from a higher layer configuration, C-JT/NC-JT-related parameters or setting values, and set an RRC parameter of the UE, based thereon. For the higher layer configuration, the UE may use a UE capability parameter, for example, tci-StatePDSCH. Here, the UE capability parameter, for example, tci-StatePDSCH, may define TCI states for a purpose of PDSCH transmission. The number of TCI states may be configured to be 4, 8, 16, 32, 64, or 128 in FRI, and may be configured to be 64 or 128 in FR2, and among the configured number, up to 8 states indicatable by 3 bits of a TCI field of DCI may be configured via an MAC CE message. The maximum number 128 denotes a value indicated by maxNumberConfiguredTClstatesPerCC in the tci-StatePDSCH parameter included in capability signaling of the UE. As such, a series of configuration processes from a higher layer configuration to an MAC CE configuration may be applied to a beamforming indication or beamforming change command for at least one PDSCH in one TRP.
As an embodiment of the disclosure, multi-DCI-based multi-TRP transmission method will be described. The multi-DCI-based multi-TRP transmission method may configure a downlink control channel for NC-JT transmission based on the multi-PDCCH.
In NC-JT based on multiple PDCCHs, when performing transmission of DCI for PDSCH scheduling of each TRP, there may be a CORESET or search space distinguished for each TRP. A CORSET or search space for each TRP may be configured as at least one of the following cases.
By distinguishing the CORESET or search space by TRP as described above, PDSCH and HARQ-ACK information may be classified for each TRP, and thus, an independent HARQ-ACK codebook for each TRP may be generated and independent PUCCH resources may be used.
The above configuration may be independent for each cell or for each BWP. For example, two different CORESETPoolIndex values are configured in PCell, whereas the CORESETPoolIndex value may not be configured in a specific SCell. Here, it may be considered that NC-JT transmission is configured in the PCell, whereas NC-JT transmission is not configured in SCell in which the CORESETPoolIndex value is not configured.
The PDSCH TCI state activation/deactivation MAC-CE applicable to the multi-DCI-based multi-TRP transmission method may follow
In case that the UE is configured to use the multi-DCI-based multi-TRP transmission method from the base station, that is, in case that the type of CORESETPoolIndex for each of a plurality of CORESETs included in PDCCH-Config, which is higher layer signaling, exceeds one, or in case that respective CORESETs have different CORESETPoolIndexes, the UE may know that the following restrictions exist for PDSCHs scheduled from PDCCHs in each of CORESETs having two different CORESETPoolIndexes.
1) In case that PDSCHs, which are indicated by the PDCCH in each CORESET having two different CORESETPoolIndexes, fully or partially overlap, the UE may apply the TCI states indicated by each PDCCH to different CDM groups, respectively. That is, two or more TCI states may not be applied to one CDM group.
2) In case that PDSCHs, which are indicated by the PDCCH in each CORESET having two different CORESETPoolIndexes, fully or partially overlap, the UE may expect that the number of actual front-loaded DMRS symbols, the number of actual additional DMRS symbols, the position of the actual DMRS symbols, and DMRS types of respective PDSCHs not to be different from one another.
3) The UE may expect that the same bandwidth part and the same subcarrier spacing are indicated from the PDCCH in each CORESET having two different CORESETPoolIndexes.
4) The UE may expect that information about a PDSCH scheduled from the PDCCH in each CORESET having two different CORESETPoolIndexes is completely included in each PDCCH.
According to another embodiment of the disclosure, a single DCI-based multi-TRP transmission method will be described. The single DCI-based multi-TRP transmission method may configure a downlink control channel for NC-JT transmission based on single PDCCH.
In single DCI-based multi-TRP transmission method, a PDSCH transmitted by multiple TRPs may be scheduled by one DCI. Here, the number of TCI states may be used as a method for indicating the number of TRPs for transmission of the corresponding PDSCH. That is, if the number of TCI states indicated in the DCI for scheduling the PDSCH is two, it may be considered as single PDCCH-based NC-JT transmission, and if the number of TCI states is one, it may be considered as single-TRP transmission. The TCI states indicated through the DCI may correspond to one or two TCI states among TCI states activated by MAC-CE. In case that the TCI states of DCI correspond to the two TCI states activated by MAC-CE, a correspondence relationship between a TCI codepoint indicated through DCI and TCI states activated by MAC-CE is established, and two TCI states may be activated by MAC-CE corresponding to the TCI codepoint.
As another example, in case that at least one codepoint among all codepoints of the TCI state field in DCI indicates two TCI states, the UE may consider that the base station may perform transmission based on the single-DCI-based multi-TRP method. Here, at least one codepoint indicating two TCI states in the TCI state field may be activated through enhanced PDSCH TCI state activation/deactivation MAC-CE.
In
The above configuration may be independent for each cell or for each BWP. For example, a PCell may include up to two activated TCI states corresponding to one TCI codepoint, whereas a specific SCell may include up to one activated TCI state corresponding to one TCI codepoint. Here, it may be considered that NC-JT transmission is configured in the PCell, whereas NC-JT transmission is not configured in the above-described SCell.
Next, a method for distinguishing between single-DCI-based multi-TRP PDSCH repetitive transmission schemes will be described. The UE may be indicated with different single-DCI-based multi-TRP PDSCH repetitive transmission schemes (e.g., TDM, FDM, SDM) according to the value indicated by a DCI field and a higher layer signaling configuration from the base station. Table 42, below, shows a method for distinguishing between single- or multi-TRP-based schemes indicated to the UE according to the value of a specific DCI field and the higher layer signaling configuration.
In Table 42, above, each column may be described as follows.
Single-TRP TDM scheme B: It refers to single TRP-based inter-slot time resource division-based PDSCH repetitive transmission. According to the above-described repetitionNumber-related Condition 1, the UE repeatedly transmits the PDSCH in the time dimension as many times as the number of slots, having the repetitionNumber having the value greater than 1, configured in the TDRA entry indicated by the time domain resource allocation field. Here, the same start symbol and symbol length of the PDSCH indicated by the TDRA entry are applied to each slot equal to the number of repetitionNumber, and the same TCI state is applied to each PDSCH repetitive transmission. The corresponding scheme is similar to a slot aggregation method in that an inter-slot PDSCH repetitive transmission is performed on time resources, but is different from slot aggregation in that it is possible to dynamically determine whether to indicate repetitive transmission based on the time domain resource allocation field in DCI
Next, a method for selecting or determining a radio link monitoring reference signal (RLM RS) in configuring or non-configuring the RLM RS will be described. The UE may be configured with a set of RLM RSs from the base station via RadioLinkMonitoringRS in RadioLinkMonitoringConfig, which is higher layer signaling, for each DL BWP of SPCell, and a specific higher layer signaling structure shown below in Table 43.
Table 44 below may indicate the configurable or selectable number of RLM RSs for each specific use according to the maximum number (Lmax) of SSBs per half frame. As shown below in Table 44, according to the Lmax value, NLR-RLM RSs may be used for link recovery or radio link monitoring, and NRLM RSs among NLR-RLM RSs may be used for radio link monitoring.
When the UE is not configured with RadioLinkMonitoringRS that is higher layer signaling, and the UE is configured with a TCI state for receiving a PDCCH in a CORESET, and in case that at least one CSI-RS is included in the corresponding TCI state, the RLM RS may be selected according to the following RLM RS selection methods.
Hereinafter, for convenience of description, higher layer/L1 parameters, such as a TCI state and spatial relation information, or cells, transmission points, panels, beams, and/or transmission directions distinguishable by indicators, such as cell ID, TRP ID, and panel ID, may be collectively described as transmission reception point (TRP), beam, or TCI state. Accordingly, for actual application, the TRP, beam, or TCI state may be suitably replaced by one of the above terms.
Hereinafter, in the disclosure, a UE may determine whether to apply cooperative communication based on whether PDCCH(s) for allocating a PDSCH to which cooperative communication is applied have a specific format, whether the PDCCH(s) for allocating the PDSCH to which cooperative communication is applied include a specific indicator indicating whether to apply cooperative communication, or whether the PDCCH(s) for allocating the PDSCH to which cooperative communication are scrambled with a specific RNTI, or by using various methods, such as assuming cooperative communication application in a specific occasion indicated through higher layer signaling. Hereinafter, for convenience of description, a case where a UE receives a PDSCH to which cooperative communication is applied based on similar conditions as above will be referred to as an NC-JT case.
Hereinafter, embodiments of the disclosure will be described in detail with reference to accompanying drawings. Hereinafter, the base station is an entity that allocates resources of a terminal, and may be at least one of a gNode B, a gNB, an eNode B, a Node B, a base station (BS), a wireless access unit, a BS controller, or a node on a network. Examples of a terminal may include user equipment (UE), a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. Hereinafter, embodiments of the disclosure will be described with an example of a 5G system, but the embodiments of the disclosure may also be applied to other communication systems having a similar technical background or channel form. For example, LTE or LTE-A mobile communication and a mobile communication technology developed after 5G may be included thereto. Accordingly, it will be understood by one of ordinary skill in the art that the disclosure may be applied to other communication systems through some modifications without departing from the scope of the disclosure. The content of the disclosure may be applied to FDD or TDD systems. Hereinafter, in the disclosure, higher signaling (or higher layer signaling) is a method for transmitting a signal from a base station to a UE using a downlink data channel of a physical layer or from a UE to a base station using an uplink data channel of a physical layer, and may be referred to as RRC signaling, PDCP signaling, or a medium access control (MAC) control element (MAC CE).
In the description of the disclosure, in case that it is determined that a detailed description of related functions or configurations may unnecessarily obscure the subject matter of the disclosure, the detailed description will be omitted. Further, the terms, as will be mentioned later, are defined by taking functionalities in the disclosure into account, but may vary depending on practices or intentions of users or operators. Accordingly, the terms should be defined based on descriptions throughout this specification.
Hereinafter, while describing embodiments of the disclosure, higher layer signaling may be signaling corresponding to at least one of or a combination of signaling methods below:
Also, L1 signaling may be signaling corresponding to at least one of or a combination of signaling methods using following physical layer channels or signaling:
Hereinafter, determining a priority between A and B in the disclosure may be variously described as selecting a higher priority according to a pre-determined priority rule and performing an operation corresponding to the higher priority, or omitting or dropping an operation having a lower priority.
Hereinafter, the term slot used in the disclosure is a general term that may refer to a specific time unit corresponding to a transmit time interval (TTI), and specifically, a slot may refer to a slot used in a 5G NR system and may also refer to a slot or subframe used in a 4G LTE system.
Hereinafter, in the disclosure, descriptions of the examples will be provided via multiple embodiments, but these are not mutually exclusive, and it is possible that one or more embodiments are applied simultaneously or in combination.
As an embodiment of the disclosure, single TCI state indication and activation method based on unified TCI scheme will be described. The unified TCI scheme may refer to a scheme of integrating and managing a transmission/reception beam management scheme which is distinguished by a spatial relation info scheme used in UL transmission and a TCI state scheme used in DL reception by the UE in existing Rel-15 and Rel-16. Therefore, in case that the UE is indicated with a TCI state from the base station, based on the unified TCI scheme, beam management may be performed using the TCI state even for UL transmission. If the UE is configured with TCI-State that is higher layer signaling having tci-stateId-r17 that is higher layer signaling from the base station, the UE may perform an operation based on the unified TCI scheme by using the corresponding TCI-State. TCI-State may exist in two types of a joint TCI state and a separate TCI state.
The first type is a joint TCI state, and the UE may be indicated, by the base station via one TCI-State, with TCI-State to be applied to both UL transmission and DL reception. If the UE is indicated with joint TCI state-based TCI-State, the UE may be indicated with a parameter to be used for DL channel estimation by using an RS corresponding to qcl-Type1 in the joint TCI state-based TCI-State and a parameter to be used as a DL reception beam or reception filter by using an RS corresponding to qcl-Type2. If the UE is indicated with joint TCI state-based TCI-State, the UE may be indicated with a parameter to be used as a UL transmission beam or transmission filter by using an RS corresponding to qcl-Type2 in corresponding joint DL/UL TCI state-based TCI-State. In this case, in case that the UE is indicated with joint TCI state, the UE may apply the same beam to both UL transmission and DL reception.
The second type is a separate TCI state, and the UE may be indicated by the base station, with UL TCI-State to be applied to UL transmission and DL TCI-State to be applied to DL reception. If the UE is indicated with a UL TCI state, the UE may be indicated with a parameter to be used as a UL transmission beam or transmission filter by using a reference RS or source RS configured within the UL TCI state. If the UE is indicated with a DL TCI state, the UE may be indicated with a parameter to be used for DL channel estimation by using an RS corresponding to qcl-Type1 and a parameter to be used as a DL reception beam or reception filter by using an RS corresponding to qcl-Type2, the parameters being configured in the DL TCI state.
If the UE is indicated with both DL TCI state and UL TCI state, the UE may be indicated with a parameter to be used as a UL transmission beam or transmission filter by using a reference RS or source RS configured within the UL TCI state, and may be indicated with a parameter to be used for DL channel estimation by using an RS corresponding to qcl-Type1 and a parameter to be used as a DL reception beam or reception filter by using an RS corresponding to qcl-Type2, the parameters being configured in the DL TCI state. In this case, in case that the DL TCI state indicated to the UE and the reference RS or source RS configured within the UL TCI state are different, the UE may individually apply a UL transmission beam and DL reception beam based on the indicated UL TCI state and DL TCI state.
The UE may be configured with up to 128 joint TCI states for each specific BWP in a specific cell via higher layer signaling by the base station, and may be configured, based on a UE capability report, with up to 64 or 128 DL TCI states among separate TCI states, for each specific BWP in a specific cell via higher layer signaling. The joint TCI states and DL TCI states among the separate TCI states may use the same higher layer signaling structure. For example, if 128 joint TCI states are configured, and 64 DL TCI states among the separate TCI states are configured, the 64 DL TCI states may be included in the 128 joint TCI states.
Up to 32 or 64 UL TCI states among the separate TCI states may be configured based on the UE capability report, for each specific BWP in a specific cell via higher layer signaling. Similar to the relationship between the joint TCI states and the DL TCI states among the separate TCI states, the same higher layer signaling structure may also be used for the joint TCI states and the UL TCI states among separate TCIs. The UL TCI states among the separate TCIs may use a higher layer signaling structure different from that for the joint TCI states and for the DL TCI states among the separate TCI states. As in the above, using the same higher layer signaling structure or using different higher layer signaling structures may be defined in the Standards. Using different higher layer signaling structures or using the same higher layer signaling structure may be distinguished via another higher layer signaling configured by the base station, based on the UE capability report including information on whether there is a use scheme supportable by the UE from among the two types.
The UE may receive a transmission/reception beam-related indication in a unified TCI scheme by using one scheme among the joint TCI state and separate TCI state configured by the base station. The UE may be configured with whether to use one of the joint TCI state and the separate TCI state, by the base station via higher layer signaling.
The UE may receive a transmission/reception beam-related indication by using one scheme selected from among the joint TCI state and the separate TCI state via higher layer signaling, wherein a method of transmission/reception beam indication from the base station may include two methods of a MAC-CE-based indication method and a MAC-CE-based activation and DCI-based indication method.
In case that the UE is configured, via higher layer signaling, to receive a transmission/reception beam-related indication by using the joint TCI state scheme, the UE may receive a MAC-CE indicating the joint TCI state from the base station and perform a transmission/reception beam applying operation, and the base station may schedule, for the UE, reception of a PDSCH including the MAC-CE via a PDCCH. If there is one joint TCI state included in the MAC-CE, the UE may transmit, to the base station, a PUCCH including HARQ-ACK information indicating whether reception of the PDSCH including the corresponding MAC-CE is successful, and may determine a UL transmission beam or transmission filter and a DL reception beam or reception filter by using the indicated joint TCI state from 3 ms after transmission of the PUCCH. If there are two or more joint TCI states included in the MAC-CE, the UE may transmit, to the base station, the PUCCH including HARQ-ACK information indicating whether reception of the PDSCH including the corresponding MAC-CE is successful, identify, from 3 ms after transmission of the PUCCH, that multiple joint TCI states indicated by the MAC-CE correspond to respective codepoints of the TCI state field of DCI format 1_1 or 1_2, and activate the joint TCI states indicated by the MAC-CE. Thereafter, the UE may receive DCI format 1_1 or 1_2, and apply one joint TCI state indicated by a TCI state field in the corresponding DCI to UL transmission and DL reception beams. In this case, DCI format 1_1 or 1_2 may include DL data channel scheduling information with or without DL assignment.
In case that the UE is configured, via higher layer signaling, to receive a transmission/reception beam-related indication by using the separate TCI state scheme, the UE may receive a MAC-CE indicating the separate TCI state from the base station and perform a transmission/reception beam applying operation, and the base station may schedule, for the UE, a PDSCH including the corresponding MAC-CE via a PDCCH. If there is one separate TCI state set included in the MAC-CE, the UE may transmit, to the base station, the PUCCH including HARQ-ACK information indicating whether reception of the corresponding PDSCH is successful. From 3 ms after transmission of the PUCCH, the UE may determine a UL transmission beam or transmission filter and a DL reception beam or reception filter by using separate TCI states included in the indicated separate TCI state set. In this case, the separate TCI state set may refer to a single separate TCI state or multiple separate TCI states that one codepoint of the TCI state field in DCI format 1_1 or 1_2 may have, and one separate TCI state set may include one DL TCI state, include one UL TCI state, or include one DL TCI state and one UL TCI state. If there are two or more separate TCI state sets included in the MAC-CE, the UE may transmit, to the base station, the PUCCH including HARQ-ACK information indicating whether reception of the corresponding PDSCH is successful, identify, from 3 ms after transmission of the PUCCH, that multiple separate TCI state sets indicated by the MAC-CE correspond to respective codepoints of the TCI state field of DCI format 1_1 or 1_2, and activate the indicated separate TCI state sets. In this case, the respective codepoints of the TCI state field of DCI format 1_1 or 1_2 may indicate one DL TCI state, indicate one UL TCI state, or indicate each of one DL TCI state and one UL TCI state. The UE may receive DCI format 1_1 or 1_2 and apply a separate TCI state set indicated by the TCI state field in the DCI to UL transmission and DL reception beams. In this case, DCI format 1_1 or 1_2 may include DL data channel scheduling information with or without DL assignment.
The MAC-CE used to activate or indicate the single joint TCI state and the separate TCI state described above may exist for each of the joint and separate TCI state schemes, and a TCI state may be activated or indicated based on one of the joint TCI state scheme and the separate TCI state scheme by using one MAC-CE. Through the figures described later, various MAC-CE structures for joint or separate TCI state activation and indication may be considered.
With reference to
In
In
An S field 25-00 may indicate the number of pieces of joint TCI state information included in a MAC-CE. As an example, if a value of the S field 25-00 is 1, the corresponding MAC-CE may indicate one joint TCI state and may include only up to a second octet, and the joint TCI state may be indicated to the UE via a TCI state ID0 field 25-00. For example, if the value of the S field 25-00 is 0, the corresponding MAC-CE may include two or more pieces of joint TCI state information, respective codepoints of the TCI state field of DCI format 1_1 or 1_2 may activate the respective joint TCI states, up to 8 joint TCI states may be activated, no second octet may exist, and there may be a first octet and a third octet to an (N+1)th octet on the MAC-CE structure in
If there is one joint TCI state transferred via the MAC-CE structure in
In
An S field 26-00 may indicate the number of pieces of separate TCI state set information included in a MAC-CE. If a value of the S field 26-00 is 1, the corresponding MAC-CE may indicate one separate TCI state set and may include only up to a third octet. If the value of the S field 26-00 is 0, the corresponding MAC-CE may include two or more pieces of separate TCI state set information, respective codepoints of the TCI state field of DCI format 1_1 or 1_2 may activate respective separate TCI state sets, and up to 8 separate TCI state sets may be activated. A C0 field 26-15 may indicate which separate TCI states are included in an indicated separate TCI state set. For example, for a value of the C0 field, a value of “00” may indicate reserve, a value of “01” may indicate one DL TCI state, a value of “10” may indicate one UL TCI state, and a value of “11” may indicate one DL TCI state and one UL TCI state, but the field is not limited to these specific values. A TCI state IDD,0 field 26-20 and TCI state IDU,0 field 26-25 may refer to a DL TCI state and UL TCI state which may be included in a zeroth separate TCI state set so as to be indicated, respectively. If the value of the C0 field is “01”, the TCI state IDD,0 field 26-20 may indicate a DL TCI state, and the TCI state IDU,0 field 26-25 may be disregarded. If the C0 field value is “10”, the TCI state IDD,0 field 26-20 may be disregarded, and the TCI state IDU,0 field 26-25 may indicate a UL TCI state. If the C0 field value is “11”, the TCI state IDD,0 field 26-20 may indicate a DL TCI state, and the TCI state IDU,0 field 26-25 may indicate a UL TCI state.
In
In
For example, if the value of the S field 28-00 is 0, the corresponding MAC-CE may include two or more pieces of separate TCI state set information, respective codepoints of the TCI state field of DCI format 1_1 or 1_2 may activate respective separate TCI state sets, and up to 8 separate TCI state sets may be activated. A C0,0 field 28-25 may have a meaning for distinguishing whether a TCI state indicated by a TCI state ID0,0 field 28-25 is a DL TCI state or a UL TCI state, and the value of 1 may indicate a DL TCI state, the DL TCI state may be indicated via the TCI state ID0,0 field 28-25, and a third octet may exist. In this case, if a value of a C1,0 field 28-20 is 1, a UL TCI state may be indicated via a TCI state ID0,0 field 28-20, and if the value of the C1,0 field 28-20 is 0, the TCI state ID1,0 field 28-30 may be disregarded. If the value of the C0,0 field 28-15 is 0, a UL TCI state may be indicated via the TCI state ID0,0 field 28-25, and a third octet may not exist. This illustration is just examples.
In
For example, if the value of the S field 29-00 is 0, the corresponding MAC-CE may include two or more pieces of separate TCI state set information, respective codepoints of the TCI state field of DCI format 1_1 or 1_2 may activate respective separate TCI state sets, and up to 8 separate TCI state sets may be activated. A C0 field 29-15 may indicate which separate TCI states are included in an indicated separate TCI state set, and for a value of the C0 field, a value of “00” may indicate reserve, a value of “01” may indicate one DL TCI state, a value of “10” may indicate one UL TCI state, and a value of “11” may indicate one DL TCI state and one UL TCI state. However, the field is not limited to the above particular values. A TCI state IDU,0 field 29-20 and TCI state IDD,0 field 29-25 may refer to a UL TCI state and DL TCI state which may be included in a zeroth separate TCI state set so as to be indicated, respectively. If the value of the C0 field 29-15 is “01”, the TCI state IDD,0 field 29-25 may indicate a DL TCI state, and the TCI state IDU,0 field 29-20 may be disregarded. If the value of the C0 field 29-15 is “10”, a third octet may be disregarded, and the TCI state IDU,0 field 29-20 may indicate a UL TCI state. If the value of the C0 field 29-15 is “11”, the TCI state IDD,0 field 29-25 may indicate a DL TCI state, and the TCI state IDU,0 field 29-20 may indicate a UL TCI state.
In
If the corresponding MAC-CE indicates a separate TCI state set, the C0,0 field 30-15 may have a meaning of distinguishing whether a TCI state indicated by a TCI state ID0,0 field 30-25 is a DL TCI state or a UL TCI state, a value of 1 may indicate a DL TCI state, the DL TCI state may be indicated via the TCI state ID0,0 field 30-25, and a third octet may exist. In this case, if a value of a C1,0 field 30-20 is 1, a UL TCI state may be indicated via a TCI state ID1,0 field 30-30, and if the value of the C1,0 field 30-20 is 0, the TCI state ID1,0 field 30-30 may be disregarded. If the value of the C0,0 field 30-15 is 0, a UL TCI state may be indicated via the TCI state ID0,0 field 30-25, and a third octet may not exist.
In
In case that the UE receives a transmission/reception beam-related indication by using a joint TCI state scheme or separate TCI state scheme via higher layer signaling, the UE may receive a PDSCH including a MAC-CE indicating the joint TCI state or separate TCI state from the base station so as to perform application to a transmission/reception beam. In case that there are two or more joint TCI states or separate TCI state sets included in the MAC-CE, from 3 ms after transmission of a PUCCH including HARQ-ACK information indicating the success or failure in reception of a corresponding PDSCH, the UE may identify that multiple joint TCI states or separate TCI state sets indicated by the MAC-CE correspond to respective codepoints of the TCI state field of DCI format 1_1 or 1_2, and may activate the indicated joint TCI states or separate TCI state sets. Thereafter, the UE may receive DCI format 1_1 or 1_2 and apply, to UL transmission and DL reception beams, one joint TCI state or separate TCI state set indicated by a TCI state field in corresponding DCI. In this case, DCI format 1_1 or 1_2 may include or not include DL data channel scheduling information (with or without DL assignment).
As described above, the UE may receive DCI format 1_1 or 1_2 which includes DL data channel scheduling information (with DL assignment) or does not include DL data channel scheduling information (without DL assignment) from a base station, and apply one joint TCI state or separate TCI state set indicated by the TCI state field in the corresponding DCI to UL transmission and DL reception beams.
The UE may transmit, to the base station, a PUCCH including HARQ-ACK indicating the success or failure in reception of DCI format 1_1 or 1_2 (32-60).
The UE may apply one joint TCI state indicated via the MAC-CE or DCI to reception of CORESETs linked to all UE-specific search spaces, reception of a PDSCH scheduled via a PDCCH transmitted from the corresponding CORESET, transmission of a PUSCH, and transmission of all PUCCH resources.
In case that one separate TCI state set indicated via the MAC-CE or DCI includes one DL TCI state, the UE may apply the one separate TCI state set to reception of CORESETs linked to all UE-specific search spaces and reception of a PDSCH scheduled via a PDCCH transmitted from the corresponding CORESET, and may apply the same to all PUSCH and PUCCH resources, based on a previously indicated UL TCI state.
In case that one separate TCI state set indicated via the MAC-CE or DCI includes one UL TCI state, the UE may apply the separate TCI state set to all PUSCH and PUCCH resources, and based on the previously indicated DL TCI state, the UE may apply the separate TCI state set to reception of CORESETs linked to all UE-specific search spaces and reception of a PDSCH scheduled via a PDCCH transmitted from the corresponding CORESET.
In case that one separate TCI state set indicated via the MAC-CE or DCI includes one DL TCI state and one UL TCI state, the UE may apply the DL TCI state to reception of CORESETs linked to UE-specific search spaces and reception of a PDSCH scheduled via a PDCCH transmitted from the corresponding CORESET, and may apply the UL TCI state to all PUSCH and PUCCH resources.
In the above-described examples of the MAC CE in
As an embodiment of the disclosure, multi-TCI state indication and activation method based on unified TCI scheme will be described. The multi-TCI state indication and activation method may refer to a case in which the number of indicated joint TCI states is extended to two or more and a case in which each of a DL TCI state and a UL TCI state included in one separate TCI state set is expanded to two or more. If one separate TCI state set can include up to two DL TCI states and up to two UL TCI states, a total of 8 combinations of DL TCI states and UL TCI states that one separate TCI state set can have may be possible ({DL, UL}={0,1}, {0,2}, {1,0}, {1,1}, {1,2}, {2,0}, {2,1}, {2,2}, where numbers indicate the number of TCI states).
In case that the UE is indicated with multiple TCI states based on the MAC-CE by the base station, the UE may receive two or more joint TCI states or one separate TCI state set from the base station via the corresponding MAC-CE. The base station may schedule reception of a PDSCH including the corresponding MAC-CE for the UE via a PDCCH, and from 3 ms after transmission of a PUCCH including HARQ-ACK information indicating the success or failure of reception of the PDSCH including the corresponding MAC-CE, the UE may determine a UL transmission beam or transmission filter and a DL reception beam or reception filter, based on the indicated two or more joint TCI states or one separate TCI state set.
In case that the UE is indicated with multiple TCI states based on DCI format 1_1 or 1_2 from the base station, respective codepoints of one TCI state field in the corresponding DCI format 1_1 or 1_2 may indicate two or more joint TCI states or two or more separate TCI state sets. In this case, the UE may receive the MAC-CE from the base station, and activate two or more joint TCI states or two or more separate TCI state sets corresponding to the respective codepoints of one TCI state field in the corresponding DCI format 1_1 or 1_2. The base station may schedule reception of a PDSCH including the corresponding MAC-CE for the UE via a PDCCH, and the UE may activate TCI state information included in the MAC-CE from 3 ms after transmission of a PUCCH including HARQ-ACK information indicating the success or failure of reception of the PDSCH including the corresponding MAC-CE.
In case that the UE is indicated with multiple TCI states based on DCI format 1_1 or 1_2 from the base station, two or more TCI state fields may exist in the corresponding DCI format 1_1 or 1_2, and one of two or more joint TCI states or two or more separate TCI state sets may be indicated based on the respective TCI state fields. In this case, the UE may receive the MAC-CE from the base station and activate the joint TCI states or separate TCI state sets corresponding to respective codepoints of the two or more TCI state fields in the corresponding DCI format 1_1 or 1_2. The base station may schedule reception of the PDSCH including the corresponding MAC-CE for the terminal via the PDCCH. The UE may activate TCI state information included in the MAC-CE from 3 ms after transmission of the PUCCH including HARQ-ACK information indicating the success or failure of reception of the PDSCH including the corresponding MAC-CE. The UE may be configured for the presence or absence of one or more additional TCI state fields via higher layer signaling, the bit length of the additional TCI state fields may be the same as that of an existing TCI state field, or the length may be adjusted based on higher layer signaling.
The UE may receive a transmission/reception beam-related indication in a unified TCI scheme by using one scheme among the joint TCI state and separate TCI state configured by the base station. The UE may be configured for using one of the joint TCI state and separate TCI state, by the base station via higher layer signaling. With respect to the separate TCI state indication, the UE may be configured via higher layer signaling so that a bit length of the TCI state field in DCI format 1_1 or 1_2 is up to 4.
The MAC-CE used to activate or indicate the multiple joint TCI states and separate TCI states described above may exist for each of the joint and separate TCI state schemes, and a TCI state may be activated or indicated based on one of the joint TCI state scheme and separate TCI state scheme by using one MAC-CE. For the MAC-CE used in the MAC-CE-based indication scheme and the MAC-CE-based activation scheme, one MAC-CE structure may be shared, and individual MAC-CE structures may be used. Through the figures described later, various MAC-CE structures for activating and indicating multiple joints or separate TCI states can be considered. In the figures to be described later, for convenience of explanation, a case where two TCI states are activated or indicated is considered, but can be similarly applied to a case where three or more TCI states are activated or indicated.
In
If the value of the S field 33-00 is 0, the corresponding MAC-CE may activate one or two joint TCI states corresponding to respective codepoints of the TCI state field of DCI format 1_1 or 1_2, or may activate one joint TCI state corresponding to respective codepoints of two TCI state fields of DCI format 1_1 or 1_2, and joint TCI states for up to 8 codepoints may be activated. If one or two joint TCI states are activated for one codepoint of one TCI state field, a TCI state ID0,Y field and TCI state ID1, Y field may refer to a first joint TCI state and second joint TCI state among two joint TCI states activated at a Y-th codepoint of the TCI state field, respectively. In case that one joint TCI state is activated for one codepoint of two TCI state fields, the TCI state ID0,Y field and TCI state ID1, Y field may refer to respective joint TCI states activated at the Y-th codepoint of the first and second TCI state fields, respectively.
In
In the MAC-CE structure in
In
For example, if the value of the S field 35-00 is 0, the corresponding MAC-CE may include information on multiple separate TCI state sets, the corresponding MAC-CE may activate one separate TCI state set corresponding to respective codepoints of the TCI state field of DCI format 1_1 or 1_2 or may activate one separate TCI state set corresponding to respective codepoints of two TCI state fields of DCI format 1_1 or 1_2, and may activate separate TCI state sets corresponding to up to 8 or 16 codepoints via higher layer signaling, as described above.
In the MAC-CE structure in
The CU,0 field having a value of “10” indicates including two UL TCI states, and thus the TCI state ID U,0,0 35-20 may include first UL TCI state information among the two UL TCI states, and the TCI state ID U,1,0 35-25 may include second UL TCI state information among the two UL TCI states.
The CD,0 field having a value of “00” indicates including no DL TCI state, and thus fourth and fifth octets may be disregarded.
The CD,0 field having a value of “01” indicates including one DL TCI state, and thus a TCI state ID D,0,0 35-30 may include one piece of DL TCI state information, and the fifth octet may be disregarded.
The CD,0 field having a value of “10” indicates including two DL TCI states, and thus the TCI state ID D,0,0 35-30 may include first DL TCI state information among the two DL TCI states, and a TCI state IDD,1,0 field 35-35 may include second DL TCI state information among the two DL TCI states.
In the aforementioned examples of the MAC CE in
<PUCCH Beam Determination Method in Case that Unified TCI Scheme-Based Multiple TCI State is Indicated>
As an example of an embodiment of the disclosure, a method for determining the number of transmission beams and transmission beams of a scheduled PUCCH when multiple TCI states are activated and indicated based on the unified TCI scheme will be described.
As described above in <Multi-TCI State Indication and Activation Method Based on Unified TCI Scheme>, if multiple TCI states are activated and indicated based on one of the joint TCI state method or separate TCI state method, the UE may determine UL transmission beam or transmission filter (hereinafter referred to as an UL transmission beam) and DL reception beam or reception filter (hereinafter referred to as a DL reception beam), according to indicated multiple TCI states. If multiple joint TCI states are indicated based on the unified TCI scheme, the UE may not only determine multiple DL reception beams, but also determine multiple UL transmission beams to be the same as DL. Alternatively, if multiple UL TCI states are activated and indicated based on the unified TCI scheme, the UE may determine an UL transmission beam according to the indicated multiple UL TCI states. In other words, if multiple UL transmission beams are determined and the UL channel (PUCCH or PUSCH) is repeatedly transmitted, this may mean that the UE may repeatedly transmit the UL channel with multiple TRPs.
When supporting PUCCH repetitive transmission based on multiple TRPs in NR Release 17, the PUCCH transmission technique has been enhanced to enable the number of spatial relation info from one to two for one PUCCH resource through MAC CE. That is, among the PUCCH resources configured through a higher layer, some PUCCH resources can be activated with one spatial relation info and the other PUCCH resources can be activated with two spatial relation info. Based on these higher layer configuration and activation of spatial relation info through MAC CE, PUCCH can be transmitted with a single TRP or with multiple TRPs depending on the scheduled PUCCH resources. In this way, NR Release 17 can support a dynamic switching method that can selectively transmit PUCCH with a single TRP or multiple TRPs.
However, if multiple UL transmission beams are activated and indicated to the UE by the unified TCI scheme as described above and applied to the UL channel in batches, the UE transmits the UL channel but can support only the method using the indicated multiple UL transmission beams. This means that it is difficult to support dynamic switching supported in NR Release 17.
In this way, multiple UL transmission beams are activated/indicated by the unified TCI scheme, and when the UE transmits PUCCH to the base station, a PUCCH beam selection method for dynamic switching function that can be supported by selecting one of multiple TRPs and single TRP will be described in detail. In addition, a single UL transmission beam is activated/indicated by the unified TCI scheme, and the operation of the UE is described in detail with an example when the UE transmits PUCCH to the base station. In a first embodiment, a method for determining whether to transmit PUCCH scheduled based on higher layer (RRC) configuration using all of or one of multiple transmission beams activated/indicated in unified TCI scheme will be described. In second and third embodiments, a method for determining whether to transmit PUCCH using all of or some of multiple transmission beams activated/indicated in MAC CE or DCI-based TCI scheme, respectively, will be described. Various methods included in each embodiment, higher layer configuration method, TCI state activation method, applicable time, etc. can be applied in combination with each other, and this means that the invention of the disclosure is not limited to the examples specifically described in each embodiment.
<First Embodiment: PUCCH Transmission Beam Determination Method Using Higher Layer Configuration for PUCCH Transmission in Case that Multiple TCI States are Indicated Based on Unified TCI Scheme>
As an example of an embodiment of the disclosure, a method for determining the UL transmission beam for PUCCH transmission according to higher layer configuration in case that the UE is indicated with multiple TCI state based on the unified TCI scheme will be described.
As described above in <Multi-TCI State Indication and Activation Method Based on Unified TCI Scheme>, the UE may receive two or more joint TCI states or one separate TCI state set from the base station via a corresponding MAC-CE. Alternatively, the UE may receive MAC-CE and activate two or more joint TCI states or two or more separate TCI state sets corresponding to respective codepoints of one TCI state field in the corresponding DCI format 1_1 or 1_2, and respective codepoints of one TCI state field in the DCI format 1_1 or 1_2 received by the UE may indicate two or more joint TCI states or separate TCI state set including two or more DL TCI states or two or more UL TCI states. Thereafter, the UE may receive the DL channel and transmit the UP channel by applying the DL reception beam and/or the UL transmission beam from the start point of the first slot after a period of time equal to beam application time (BAT). When defining this operation as a default operation and transmitting PUCCH, it may determine whether to transmit PUCCH using all or some of the multiple UL transmission beams indicated using the following additional higher layer configuration (for example, only the first transmission beam or only the second transmission beam among the two transmission beams).
An additional higher layer configuration method may be considered divided in [Method 1] to be described later such as a method for indicating whether multiple UL transmission beams can be applied by higher layer configuration when transmitting PUCCH, and [Method 2] such as a method for indicating information on which beam to use among the indicated multiple UL transmission beams. For convenience of description of [Method 1] and [Method 2], as illustrated in
The base station may configure a new higher layer parameter to indicate whether to apply all UL transmission beams indicated by the unified TCI scheme to the UE to PUCCH transmission. As an example of a new higher layer parameter, it may be configured as ‘enableAllULTCIstates’. The base station may configure one of {support} and {non support} to the UE as the value of the new higher layer parameter ‘enableAllULTCIstates’. Alternatively, the base station may configure or may not configure {support} to the UE as the value of the new higher layer parameter ‘enableAllULTCIstates’. If the base station configures or does not configure ‘enableAllULTCIstates’ with {non support}, the UE may use the first (or second or nth (n=3 or 4 or number of all UL transmit beams indicated by the unified TCI scheme) UL transmission beam among all UL transmission beams (e.g., two UL transmission beams) indicated by the unified TCI scheme to transmit PUCCH. Here, among the UL transmission beams indicated by the unified TCI scheme, the first UL transmission beam may refer to the transmission beam indicated by the first activated TCI state among the multiple activated TCI states included in the corresponding codepoint, and the second or later UL transmission beam can be similarly expanded and considered. If the base station configures {support} as the value of ‘enableAllULTCIstates’, the UE can transmit PUCCH using all UL transmission beams (e.g., two UL transmission beams) indicated by the unified TCI scheme. The new higher layer parameter ‘enableAllULTCIstates’ may be included in the higher layer configurations for each PUCCH resource, each PUCCH format, or for the entire PUCCH, as detailed below. The method is only an example, and the base station may configure a higher layer parameter with a different name than ‘enableAllULTCIstates’ that supports similar operations to the UE. Additionally, other types of information (e.g. {1} or {2}, etc.) may be configured as a candidate value for the new higher layer parameter.
The base station may configure a new higher layer parameter to indicate the UL transmission beam applied to PUCCH transmission among all UL transmission beams indicated by the unified TCI scheme to the UE. As an example of a new higher layer parameter, it may be configured as ‘enableULTCIstate’. In case that two UL transmission beams are indicated to the UE by the unified TCI scheme, the base station may configure one of {enableFirstTCI} (similar to Method 1, no value may be configured), {enableSecondTCI}, and {enableAllTCI} as the value of new higher layer parameter ‘enableULTCIstate’ to the UE. Alternatively, the base station may configure or may not configure one of {enableSecondTCI} and {enableAllTCI} as the value of the new higher layer parameter ‘enableULTCIstate’ to the UE. In case that M UL transmission beams are indicated to the UE by the unified TCI scheme, the base station may configure the new higher layer parameter ‘enableULTCIstate’ to the UE by selecting one or two values from 1 to M, or a value corresponding to the maximum number of beams that the UE can support. Here, as a number of values that may be configured to ‘enableULTCIstate’, one or two or the maximum number of supportable beams as well as any number between two and the maximum number of supportable beams can be considered. In the specific example described later, it is assumed that up to two beams can be supported.
If ‘enableULTCIstate’ is configured to {enableFirstTCI} (or no value is configured), the UE may transmit PUCCH with the first UL transmission beam among all UL transmission beams (e.g., two UL transmission beams) indicated by the unified TCI scheme. Similarly, if ‘enableULTCIstate’ is configured to {enableSecondTCI}, the UE may transmit PUCCH using the second UL transmission beam among all UL transmission beams (e.g., two UL transmission beams) indicated by the unified TCI scheme. If ‘enableULTCIstate’ is configured to {enableAllTCI}, the UE may transmit PUCCH using all uplink transmission beams (for example, two UL transmission beams) indicated by the unified TCI scheme. The new higher layer parameter ‘enableULTCIstate’ may be included in the higher layer configuration for each PUCCH resource, each PUCCH format, or for the entire PUCCH, as detailed below. The above method is only an example, and the base station may configure a higher layer parameter with a different name from ‘enableULTCIstate’ that supports similar operations to the UE.
[Higher layer configuration method 1: Configuration for each PUCCH resource] The base station may configure the above-described new higher layer parameter (e.g., ‘enableAllULTCIstates’ or ‘enableULTCIstate’) for each higher layer parameter PUCCH-resource. That is, a new higher layer parameters may be added for each higher layer configuration for each PUCCH resource. For example, PUCCH-Resource with a newly added higher layer parameter may be constituted as shown in Table 45 below. This is one example, and the exact name and candidate value of the newly added higher layer parameter may be different, but the function and operation of the newly added higher layer parameter may be the same or similar to Methods 1 and 2 described above. Tables 46 to 49, which will be described later, are only examples of each case, and the names and candidate values of the newly added higher layer parameters may be different, but the function and operation of the newly added higher layer parameters are the same or similar to Methods 1 and 2 described above. By configuring a new higher layer parameter value for each different PUCCH resource according to Table 45, the base station may select one from multiple PUCCH resource candidates and indicate the selected PUCCH resource to the UE through the PUCCH resource indicator area (PRI field) in the DCI. In this case, the number of PUCCH transmission beams transmitted by the UE may be determined according to the higher layer configuration of the scheduled PUCCH resource. Based on this operation, the base station may select whether to instruct the UE to transmit PUCCH using only one or both of the two UL beams indicated by the unified TCI method.
The base station may configure the above-described new higher layer parameter (e.g., ‘enableAllULTCIstates’ or ‘enableULTCIstate’) for each higher layer parameter PUCCH-ResourceGroup. That is, a new higher layer parameters may be added for each PUCCH resource group. For example, PUCCH-ResourceGroup with a newly added higher layer parameter may be constituted as shown in Table 46 below. By configuring a new higher layer parameter value for each PUCCH resource group according to Table 46, the base station may configure information for the same PUCCH transmission beam selection for the PUCCH resource(s) included in the same PUCCH resource group (i.e., information on whether to transmit PUCCH using one or both of the two UL transmission beams indicated based on the unified TCI). Thereafter the base station may select one of multiple PUCCH resources and indicate the selected PUCCH resource to the UE through the PUCCH resource indicator area (PRI field) in the DCI. In this case, the number of PUCCH transmission beams transmitted by the UE may be determined according to the higher layer configuration of the PUCCH resource group including scheduled PUCCH resource. Based on this operation, the base station may select whether to instruct the UE to transmit PUCCH using only one or both of the two UL beams indicated by the unified TCI method.
The base station may configure the above-described new higher layer parameter (e.g., ‘enableAllULTCIstates’ or ‘enableULTCIstate’) for each higher layer parameter PUCCH-ResourceSet. That is, a new higher layer parameters may be added for each PUCCH resource set. For example, PUCCH-ResourceSet with a newly added higher layer parameter may be constituted as shown in Table 47 below. By configuring a new higher layer parameter value for each PUCCH resource set according to Table 47, the base station may configure information for the same PUCCH transmission beam selection for the PUCCH resource(s) included in the same PUCCH resource set (i.e., information on whether to transmit PUCCH using one or both of the two UL transmission beams indicated based on the unified TCI). Thereafter the base station may select one of multiple PUCCH resources and indicate the selected PUCCH resource to the UE through the PUCCH resource indicator area (PRI field) in the DCI. In this case, the number of PUCCH transmission beams transmitted by the UE may be determined according to the higher layer configuration of the PUCCH resource set including scheduled PUCCH resource. Based on this operation, the base station may select whether to instruct the UE to transmit PUCCH using only one or both of the two UL beams indicated by the unified TCI method.
The base station may configure the above-described new higher layer parameter (e.g., ‘enableAllULTCIstates’ or ‘enableULTCIstate’) to higher layer parameters PUCCH-format0 and PUCCH-format1 and PUCCH-format2 and PUCCH-format3 and PUCCH-format4. For example, PUCCH-format0 and PUCCH-format1 and PUCCH-format2 and PUCCH-format3 and PUCCH-format4 with a newly added higher layer parameter may be constituted as shown in Table 48 below. By configuring a new higher layer parameter value for each PUCCH format according to Table 48, the base station may configure information for the same PUCCH transmission beam selection for the PUCCH resource(s) configured with the same PUCCH format (i.e., information on whether to transmit PUCCH using one or both of the two UL transmission beams indicated based on the unified TCI). Thereafter the base station may select one of multiple PUCCH resources and indicate the selected PUCCH resource to the UE through the PUCCH resource indicator area (PRI field) in the DCI. In this case, the number of PUCCH transmission beams transmitted by the UE may be determined according to the higher layer configuration of the format of the scheduled PUCCH resource. Based on this operation, the base station may select whether to instruct the UE to transmit PUCCH using only one or both of the two UL beams indicated by the unified TCI method.
The base station may configure the above-described new higher layer parameter (e.g., ‘enableAllULTCIstates’ or ‘enableULTCIstate’) to a higher layer parameter PUCCH-Config. That is, a new higher layer parameters may be added for PUCCH. For example, PUCCH-Config with a newly added higher layer parameter may be constituted as shown in Table 49 below. By configuring a new higher layer parameter value for PUCCH according to Table 49, the base station may configure information for the same PUCCH transmission beam selection for all PUCCH resource(s) in the corresponding supporting cell (i.e., information on whether to transmit PUCCH using one or both of the two UL transmission beams indicated based on the unified TCI). Thereafter the base station may select one of multiple PUCCH resources and indicate the selected PUCCH resource to the UE through the PUCCH resource indicator area (PRI field) in the DCI. In this case, the number of PUCCH transmission beams transmitted by the UE may be determined according to the higher layer configuration PUCCH-Config for scheduled PUCCH resource transmission. Based on this operation, the base station may select whether to instruct the UE to transmit PUCCH using only one or both of the two UL beams indicated by the unified TCI method.
[Operation 1: Case where Multiple TCI States are Activated/Indicated]
As in the specific examples of the first embodiment described above, an operation of the UE in case that based on the unified TCI scheme, a codepoint including multiple (e.g., two) TCI states and codepoint including a single TCI state are activated and a codepoint including multiple TCI states is indicated via DCI will be described. Here, the TCI state is a TCI state for PUCCH transmission and may mean a joint TCI state or UL TCI state. If a codepoint including multiple TCI states is indicated to the UE via DCI, and the UE is ready to perform UL transmission with the indicated beam after the beam application time (BAT), the UE may transmit PUCCH using one or some or entire of multiple UL transmission beams indicated in consideration of one or combination of the above-described [Method 1] to [Method 2] and [Higher layer configuration method 1] to [Higher layer configuration method 5]. That is, in case that the UE is configured with parameters for multiple TCI states according to the higher layer configuration, and indicated with multiple TCI states according to the above-described process, the UE may transmit PUCCH using one or some or entire of the indicated multiple UL transmission beams, based on the parameters configured via a higher layer.
[Operation 2: Case where a Single TCI States is Activated/Indicated]
An operation of the UE in case that based on the unified TCI scheme, a codepoint including multiple (e.g., two) TCI states and codepoint including a single TCI state are activated and a codepoint including a single TCI state is indicated via DCI will be described. Here, the TCI state is a TCI state for PUCCH transmission and may mean a joint TCI state or UL TCI state. If a codepoint including a single TCI states is indicated to the UE via DCI, and the UE is ready to perform UL transmission with the indicated beam after the BAT, the UE may transmit PUCCH using beam indicated regardless of [Method 1] to [Method 2] and [Higher layer configuration method 1] to [Higher layer configuration method 5].
[Operation 3: Case where Smaller Number of TCI States are Activated/Indicated than the Number of PUCCH Transmission Beams Indicated by a New Higher Layer Parameter for Scheduled PUCCH Resource]
An operation of the UE in case that based on the unified TCI scheme, a codepoint including multiple (e.g., four) TCI states and codepoint including a single TCI state are activated and a codepoint including a single TCI state is indicated via DCI will be described. Here, the TCI state is a TCI state for PUCCH transmission and may mean a joint TCI state or UL TCI state. If a codepoint including two TCI states is indicated to the UE via DCI, and the UE is ready to perform UL transmission with the indicated beam after the BAT, and the UE is configured to transmit PUCCH with a larger number of beams than the number of beams indicated with a new higher layer parameter for the scheduled PUCCH resource (in this specific example, a new higher layer parameter is configured so as to transmit PUCCH with four beams), the UE may transmit PUCCH using beam indicated regardless of [Method 1] to [Method 2] and [Higher layer configuration method 1] to [Higher layer configuration method 5].
The operation of the UE is as follows. The UE may transmit UE capability to the base station (37-11). In this case, as described above, the UE may perform UE reporting including whether to support the unified TCI, whether the PUCCH transmission beam may be determined based on the higher layer parameters configured as in the first embodiment described above, or information such as PUCCH transmission related UE capability. Thereafter, the UE may receive the higher layer parameter from the base station (37-12). Here, the UE may receive, from the base station, configuration information about higher layer parameters to support the unified TCI-based operation and new higher layer parameters within the above-described PUCCH-related configurations. The UE may receive a PDCCH (e.g., DCI format 1_1 or 1_2) for scheduling from the base station (37-13). In this case, the corresponding PDCCH may schedule PDSCH and PUCCH including a grant, or may schedule only PUCCH without including a grant. If the corresponding PDCCH includes a grant, the UE may receive the scheduled PDSCH (37-14). If only PUCCH is scheduled without grant, operation 37-14 may be omitted. Thereafter, the UE may identify the scheduled PUCCH resources to prepare for PUCCH transmission and perform PUCCH transmission preparation (37-15). This process may be performed after receiving the PDSCH (37-14) or after receiving the scheduling PDCCH (37-13), but for convenience of description, it is assumed that it operates as shown in
<Second Embodiment: PUCCH Transmission Beam Determination Method According to Scheduled PUCCH Resource in Case that Multiple TCI States are Indicated Based on Unified TCI Scheme>
As an example of an embodiment of the disclosure, a method for determining a PUCCH transmission beam according to scheduled PUCCH resource configuration in case that multiple TCI states are indicated based on the unified TCI scheme will be described. In the second embodiment, a method for determining a PUCCH transmission beam according to the number of repeated transmissions of scheduled PUCCH resources and a method for implicitly determining a PUCCH transmission beam according to a PUCCH resource group including the scheduled PUCCH resource will be described.
NR Release 15/16 supports repeated transmission between slots for PUCCH formats 1, 3, and 4 to transmit PUCCH with high reliability. In this case, the base station may configure the number of PUCCH repeated transmissions to the UE as ‘nrofSlots’ in a higher layer parameter ‘PUCCH-FormatConfig’. That is, the NR Release 15/16 supports repeated transmission between slots for PUCCH formats 1, 3, and 4, and the number of repetitions may be configured for each PUCCH format. Based on this configuration, the UE may transmit PUCCH resources of the same format to the base station with the same number of repetitions.
As an NR Release 17 supports multiple TRPs, it supports repeated transmission of not only PUCCH formats 1, 3, and 4, but also PUCCH formats 0 and 2. In addition, the NR Release 17 has been enhanced to support not only inter-slot repetitive transmission, but also intra-slot repetitive transmission. In addition, the number of repetitions configured to a higher layer for each PUCCH format has also been enhanced so that the number of repetitions may be configured to a higher layer for each PUCCH resource. Therefore, the number of repetitions of the PUCCH transmitted by the UE may vary depending on the scheduled PUCCH resource configurations.
If the UE transmits the PUCCH according to one of NR Release 15 or 16 or 17, the number of repeated transmissions may be determined according to the PUCCH format of the scheduled PUCCH or according to PUCCH resources. Depending on the number of repetitions for PUCCH transmission determined in this way, the UE may transmit the PUCCH using one, some, or all of the indicated multiple UL transmission beams in case that multiple TCI states are indicated by the unified TCI scheme. The UE may use the number of repetitions of the scheduled PUCCH resource to determine the number of UL transmission beams and UL transmission beam for PUCCH transmission. For example, if the number of repetitions of the scheduled PUCCH resource is greater than or equal to 2, the UE may use all of the multiple UL transmission beams indicated by the unified TCI scheme for PUCCH transmission. If the scheduled PUCCH resource is not transmitted repeatedly (if the number of repetitions is 1), the UE may transmit PUCCH to the base station using the first (or second) UL transmission beam among multiple UL transmission beams indicated by the unified TCI scheme. Such operations may be defined by a prior rule without a higher layer configuration between the base station and the UE, MAC CE-based activation, or DCI-based indication, and the UE may select an UL beam according to a predefined operation. Alternatively, a reference for the number of PUCCH repetition transmissions for using all indicated UL beams may be defined as a value other than 2. Other values may be values predefined by the base station and UE, as described above, or may be configured by the base station to the UE as a higher layer parameter. If a reference repetition number for applying all beams among all UL transmission beams indicated based on the unified TCI is configured as a higher layer parameter, the UE may determine whether to apply all of indicated UL transmission beams or only some or one of indicated UL transmission beams by comparing whether the repetition number of the scheduled PUCCH resource is greater than or equal to the reference repetition number configured as a higher layer parameter.
Unlike the above-described [Higher layer configuration method 2], it may implicitly determine whether to apply all, or some or one of UL transmission beams indicated based on the unified TCI to PUCCH transmission according to a PUCCH resource group, without a higher layer configuration. That is, the number of indicated UL transmission beams applied to PUCCH transmission may be determined according to the PUCCH resource group to which the PUCCH resource belongs according to a higher layer configuration. As an example, the fourth (or may be configured as one group other than the fourth) PUCCH resource group among up to four PUCCH resource groups that may be configured may be predefined by the base station and UE to apply all indicated UL transmission beams to PUCCH transmission. Alternatively, the base station and UE may predefine all UL transmission beams indicated by multiple PUCCH resource groups, rather than one PUCCH resource group, so as to apply all UL transmission beams to PUCCH transmission. For the remaining PUCCH resource groups that are not defined to apply all indicated UL transmission beams to PUCCH transmission, the base station and UE may predefine the remaining PUCCH resource groups to apply some or one of the indicated UL transmission beams (for example, the first UL transmission beam or any UL transmission beam) for an UL transmission beam.
<Third Embodiment: PUCCH Transmission Beam Determination Method Using MAC CE Signaling for PUCCH Transmission in Case that Multiple TCI States are Indicated Based on Unified TCI Scheme>
As an example of an embodiment of the disclosure, a method for using MAC CE signaling to determine an UL transmission beam used for PUCCH transmission among multiple TCI states indicated by a unified TCI scheme will be described.
The above-described content in the first embodiment is a method for determining an UL transmission beam used for PUCCH transmission among multiple TCI states indicated by the TCI scheme based on a higher layer configuration. As another method for determining an UL transmission beam used for PUCCH transmission, the UE may determine whether to use all or one or some of the UL transmission beams indicated by the unified TCI scheme for PUCCH transmission by using MAC CE signaling. In other words, the base station may transmit, to the UE, new MAC CE signaling that can indicate whether to use all or one or some of beams for PUCCH transmission for each PUCCH resource, each PUCCH resource group, or all PUCCHs, etc., through PDSCH.
In case that up to two unified TCI states (or two UL TCI states) may be indicated with one codepoint based on unified TCI, a PUCCH resource 38-03 indicated by the corresponding MAC CE, among the two TCI states indicated using a MAC CE structure as illustrated in
This is just one example and may be indicated via another similar form of MAC CE, and as in an example, a method for applying the MAC CE to a PUCCH configuration level (for each PUCCH resource configuration, etc.) other than a PUCCH resource or PUCCH resource group may also be considered.
As illustrated in
[Option 1: Applicable after MAC CE Application Time (3 ms)]
Even if the UE receives the PDCCH 39-50, which schedules a new PUCCH 39-55 (PDSCH may be also scheduled together with PUCCH) according to Option 1, before the activation time for the previously received MAC CE, the UE may determine whether to transmit PUCCH using all or one or some of the multiple UL transmission beams indicated by the newly updated MAC CE (39-40) according to the newly updated MAC CE. This is an operation to determine that the base station has scheduled the PUCCH, assuming that the UE has successfully received the PDSCH including the new MAC CE.
[Option 2: Applicable to a Case of being Scheduled with DCI Received after MAC CE Application Time]
Since the PDCCH 39-50 scheduling a new PUCCH 39-55 has been received before the activation time (39-35) for the previously received MAC CE according to Option 2, the UE may transmit, to the base station, PUCCH according to the transmission beam selection method indicated by the existing MAC CE (39-35), instead of following the indication updated with the corresponding MAC CE. This is an operation that determines that the base station has scheduled the PUCCH, assuming that the UE has not yet reflected the MAC CE.
To avoid the ambiguity of the above-described UE operation, the base station does not transmit, to the UE, the PDCCH 39-50 that schedules a new PUCCH 39-55 during the MAC CE activation time (3920) after the PUCCH 39-10 including ACK. The UE may not expect to receive the PDCCH 39-50 scheduling PUCCH 39-55 during the MAC CE activation time (39-20) after the PUCCH including ACK. In addition, as will be described later, if similar (or identical) operations are supported for PUSCH as described for PUCCH, the base station does not transmit, to the UE, the PDDCH that schedules PUSCH during the MAC CE activation time after the PUCCH including ACK, and the UE may not expect to receive the corresponding PDCCH.
<Fourth Embodiment: Method for Determining a Beam for PUCCH Transmission Using DCI in Case that Multiple TCI States are Indicated Based on a Unified TCI Scheme>
As an example of an embodiment of the disclosure, a method for using DCI to determine an UL transmission beam used for PUCCH transmission among multiple TCI states indicated by the unified TCI scheme will be described.
Based on the above-mentioned higher layer parameter, PUCCH resource information, or MAC CE, it may determine the UL transmission beam used for PUCCH transmission among the multiple TCI states (joint TCI state or UL TCI state) indicated based on the unified TCI scheme. In the fourth embodiment, a new field in DCI may be constituted as another example for determining an UL transmission beam used for PUCCH transmission among TCI states (joint TCI state or UL TCI state). For example, if up to two joint TCI states or two UL TCI states may be indicated via DCI, the base station may indicate the UL transmission beam used for PUCCH transmission by constituting a new area in the DCI that schedules PUCCH with 2 bits. For example, if 2 bits of the new area included in the DCI are indicated as 00, the UE may transmit PUCCH using only the first UL transmission beam among two UL transmission beams in which two joint TCI states or two UL TCI states are indicated via DCI. If 2 bits of the new area included in the DCI are indicated as 01, the UE may transmit PUCCH using only the second UL transmission beam among the two UL transmission beams. If 2 bits of the new area included in the DCI are indicated as 10, the UE may use both UL transmission beams to transmit PUCCH by mapping the first UL transmission beam and second UL transmission beam to PUCCH repeated transmission in the order. Here, the mapping between PUCCH repetitive transmission and beams may follow a sequential scheme (e.g., mapping as 11221122 . . . when the first beam is expressed as 1 and the second beam is expressed as 2) or cyclical scheme (e.g., mapping as 1212 . . . ). If 2 bits of the new area included in the DCI are indicated as 11, the UE may use both UL transmission beams and maps the second UL transmission beam and first UL transmission beam to PUCCH repeated transmission in the order to transmit PUCCH. Here, the mapping between the PUCCH repetitive transmission and the beam may follow a sequential scheme (e.g., mapping as 22112211 . . . ) or cyclical scheme (e.g., mapping as 2121 . . . ).
<Beam Determination Method for PUSCH Transmission in Case that Multiple TCI States are Indicated Based on a Unified TCI Scheme>
As an embodiment of the disclosure, a method for determining a beam for PUSCH transmission when multiple TCI states (joint TCI state or UL TCI state) are indicated by the unified TCI scheme will be described.
The UL transmission beam for PUSCH transmission may also be determined similarly to the constitutions of the PUCCH-related embodiment (first to fourth embodiments), in which the method for determining the UL transmission beam for PUCCH transmission is described. As an example, similar to the first embodiment, the base station may configure to determine an UL beam for PUSCH transmission among multiple TCI states by adding a new higher layer parameter to a higher layer configuration for PUSCH transmission. For example, a new higher layer parameter may be configured in PUSCH-Config or may be included in higher layer configuration information for another PUSCH transmission.
Alternatively, similar to the second embodiment, it may be configured to determine an UL beam for PUSCH transmission among multiple TCI states indicated based on the scheduled repetition number of PUSCH, the size of resources, and the like. For example, if the number of repetitions of the scheduled PUSCH is greater than a certain number (which may be configured with a higher layer parameter or may be any number predefined by the base station and UE), PUSCH may be transmitted using all UL transmission beams according to multiple indicated TCI states. If the number of PUSCH repetitions is less than a certain number, the PUSCH may be transmitted using only one or some of multiple UL transmission beams (e.g., the first UL transmission beam).
Alternatively, using MAC CE as in the third embodiment, a new area within DCI as in the fourth embodiment, or SRS resource set indicator area, which is a new DCI area introduced in NR Release 17 to support dynamic switching between single TRP PUSCH transmission and multiple TRP PUSCH transmission (when supporting multiple TRP or two SRS resource sets with usage of codebook or nonCodebook, 2 bit is configured, otherwise 0 bit is configured), it may be configured to determine an UL beam for PUSCH transmission among multiple indicated TCI states.
With reference to
The transceiver may transmit a signal to or receive a signal from a base station. Here, the signal may include control information and data. To this end, the transceiver may include an RF transmitter configured to perform up-conversion and amplification of a frequency of a transmitted signal, an RF receiver configured to perform low-noise amplification of a received signal and down-conversion of a frequency, and the like. However, this is only an embodiment of the transceiver, and the elements of the transceiver are not limited to the RF transmitter and RF receiver.
In addition, the transceiver may receive a signal via a radio channel and output the signal to the processor, and may transmit, via a radio channel, a signal output from the processor.
The memory may store a program and data necessary for operation of the UE. Also, the memory may store control information or data included in a signal transmitted or received by the UE. The memory may include a storage medium or a combination of storage media, such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. There may be multiple memories.
Also, the UE processor 4005 may control a series of procedures so that the UE is able to operate according to the aforementioned embodiments. For example, the UE processor 4005 may receive DCI including two layers and control the elements of the UE to simultaneously receive multiple PDSCHs. There may be multiple UE processors 4005, and the UE processor 4005 may control operations of the elements of the UE by executing programs stored in the memory.
For example, the UE processor 4005 may receive a radio resource control (RRC) message including information for determining the transmission configuration indicator (TCI) state from the base station, receive downlink control information (DCI) including information indicating a unified TCI state from the base station, and determine the TCI state for physical uplink control channel (PUCCH) based on the information for determining the TCI state in case that multiple TCI states are indicated based on the above DCI, and control to transmit UL control information to the base station on the PUCCH based on the determined TCI state.
In this case, the information for determining the TCI state may be configured for each PUCCH resource or each PUCCH resource group in the RRC message. Additionally, the information for determining the TCI state may indicate one of application of the first TCI state among the multiple TCI states, application of the second TCI state among the multiple TCI states, and application of all TCI states among the multiple TCI states.
In addition, the UE processor 4005 may control to receive a DCI scheduling a physical uplink shared channel (PUSCH) from the base station, and the DCI scheduling the PUSCH may include information for determining the TCI state for PUSCH transmission among the multiple TCI states.
With reference to
The transceiver may transmit a signal to or receive a signal from the UE. Here, the signal may include control information and data. To this end, the transceiver may include an RF transmitter configured to perform up-conversion and amplification of a frequency of a transmitted signal, an RF receiver configured to perform low-noise amplification of a received signal and down-conversion of a frequency, etc. However, this is merely an embodiment of the transceiver, and the elements of the transceiver are not limited to the RF transmitter and RF receiver.
Also, the transceiver may receive a signal via a radio channel, may output the signal to the processor, and may transmit the signal output from the processor via the radio channel.
The memory may store a program and data necessary for operation of the base station. Also, the memory may store control information or data included in a signal transmitted or received by the base station. The memory may include a storage medium or a combination of storage media, such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. Also, there may be multiple memories.
The base station processor 4105 may control a series of procedures so that the base station operates according to the aforementioned embodiments of the disclosure. For example, the base station processor 4105 may constitute DCI of two layers including allocation information for multiple PDSCHs, and may control each element of the base station to transmit the DCI. There may be multiple base station processors 4105, and the base station processor 4105 may control the elements of the base station by executing programs stored in the memory.
For example, the base station processor 4105 may transmit, to the UE, a radio resource control (RRC) message including information for determining a transmission configuration indicator (TCI) state, transmit, to the UE, downlink control information (DCI) including information indicating a unified TCI state, and control to receive uplink control information from the UE on a physical uplink control channel (PUCCH) based on the TCI state determined based on the multiple TCI states. Additionally, in case that the multiple TCI states are indicated based on the DCI, the TCI state for the PUCCH may be determined based on information for determining the TCI state for UL transmission.
Additionally, information for determining the TCI state may be configured for each PUCCH resource or each PUCCH resource group in the RRC message. Additionally, the information for determining the TCI state may indicate one of application of the first TCI state among the multiple TCI states, application of the second TCI state among the multiple TCI states, and application of all TCI states among the multiple TCI states.
In addition, the base station processor 4105 may control to transmit the DCI scheduling a physical uplink shared channel (PUSCH) to the UE, and the DCI scheduling the PUSCH may include the information for determining the TCI state for PUSCH transmission among the multiple TCI states.
The methods according to the embodiments described in the claims or specification of the disclosure may be implemented by hardware, software, or a combination of hardware and software.
In case that the methods are implemented by software, a computer-readable storage medium for storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium may be configured for execution by one or more processors within the electronic device. The at least one program may include instructions that cause the electronic device to perform the methods according to the embodiments of the disclosure as defined by the appended claims and/or disclosed herein.
The programs (software modules or software) may be stored in non-volatile memories including a random access memory (RAM) and a flash memory, a read only memory (ROM), an electrically erasable programmable read only memory (EEPROM), a magnetic disc storage device, a compact disc-ROM (CD-ROM), digital versatile discs (DVD), or other type optical storage devices, or a magnetic cassette. Alternatively, any combination of some or all of them may form a memory in which the program is stored. Further, a plurality of such memories may be included.
Also, the programs may be stored in an attachable storage device which may access the electronic device through communication networks constituted with the Internet, Intranet, local area network (LAN), wide LAN (WLAN), and storage area network (SAN) or a combination thereof. Such a storage device may access a device performing the embodiments of the disclosure via an external port. Further, a separate storage device on the communication network may access a device performing the embodiments of the disclosure.
In the specific embodiments of the disclosure described above, elements included in the disclosure are expressed in a singular or plural form according to the specific embodiments of the disclosure. However, the singular or plural expression is appropriately selected for convenience of explanation and the disclosure is not limited to the singular or plural elements. As such, an element expressed in a plural form may also be configured as a single element, and an element expressed in a singular form may also be configured as plural elements.
Meanwhile, the embodiments of the disclosure described with reference to the present specification and drawings are merely illustrative of specific examples to easily facilitate technical description and understanding of the disclosure, and are not intended to limit the scope of the disclosure. In other words, it will be apparent to one of ordinary skill in the art that other modifications based on the technical ideas of the disclosure are feasible. Also, the respective embodiments of the disclosure may be combined with each other as required. For example, a portion of one embodiment of the disclosure and a portion of another embodiment of the disclosure may be combined with each other to enable a base station and UE to operate. For example, a portion of a first embodiment of the disclosure and portion of a second embodiment of the disclosure may be combined with each other to enable a base station and UE to operate. Also, the embodiments are provided based on a FDD LTE system, but other modifications based on technical ideas of the embodiments may be implemented on other systems, such as a TDD LTE system, a 5G or NR system, and the like.
Meanwhile, in a drawing for describing a method of the disclosure, an order of the description does not necessarily correspond to an order of execution, and the order may be changed or executed in parallel.
Alternatively, in the drawing for describing the method of the disclosure, some components may be omitted and only some components may be included within a range that does not depart from the essence of the disclosure.
Further, the method of the disclosure may be performed in a combination of some or all of content included in each embodiment within a range that does not depart from the essence of the disclosure.
Various embodiments of the disclosure have been described above. The above description of the disclosure is for illustrative purposes, and the embodiments of the disclosure are not limited to the disclosed embodiments. A person skilled in the art to which this disclosure pertains will understand that the disclosure can be easily modified into another specific form without changing its technical idea or essential features. The scope of the disclosure is indicated by the claims described below rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2022-0018154 | Feb 2022 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2023/001557 | 2/3/2023 | WO |
