Patent Application
20250202555
The present disclosure relates to a cellular communications system and, more specifically, to Channel State Information Reference Signal (CSI-RS) in a Radio Access Network (RAN) of a cellular communications system.
With MU-MIMO, two or more User Equipments (UEs) in the same cell are co-scheduled on the same time-frequency resource(s). That is, two or more independent data streams are transmitted to different UEs at the same time, and the spatial domain can typically be used to separate the respective streams. By transmitting several streams simultaneously, the capacity of the system can be increased. This, however, comes at the cost of reducing the Signal to Interference plus Noise Ratio (SINR) per stream, as the power must be shared between streams and the streams will cause interference to each-other.
For Channel State Information (CSI) measurement and feedback, CSI-RS are defined. A CSI-RS is transmitted on each antenna port and is used by a UE to measure the downlink channel between each of the transmit antenna ports and each of its receive antenna ports. The transmit antenna ports are also referred to as CSI-RS ports. The supported number of antenna ports in Third Generation Partnership Project (3GPP) New Radio (NR) are currently {1,2,4,8,12,16,24,32}. By measuring the received CSI-RS, a UE can estimate the channel that the CSI-RS is traversing, including the radio propagation channel and antenna gains. The CSI-RS for the above purpose is also referred to as Non-Zero Power (NZP) CSI-RS.
CSI-RS can be configured to be transmitted in certain Resource Elements (REs) in a slot and certain slots.
In addition, Interference Measurement Resource (IMR) is defined in NR for a UE to measure interference. An IMR resource contains 4 Res, either 4 adjacent Res in frequency in the same Orthogonal Frequency Division Multiplexing (OFDM) symbol or 2 by 2 adjacent Res in both time and frequency in a slot. By measuring both the channel based on NZP CSI-RS and the interference based on an IMR, a UE can estimate the effective channel and noise plus interference to determine the CSI, i.e., rank, precoding matrix, and channel quality.
Furthermore, a UE in NR may be configured to measure interference based on one or multiple NZP CSI-RS resource.
Due to oscillator imperfections, transmission and reception may not be synchronized in time and/or frequency, which can cause inter- and intra-symbol interference. In NR, TRS was introduced that can be used by the UE for synchronization.
In NR 3GPP specifications, TRS can be configured when CSI report setting is not configured or when the higher layer parameter ‘reportQuantity’ in the CSI-ReportConfig Information Element (IE), associated with all the report settings linked with the CSI-RS resource set containing the TRS(s) is set to ‘none’. This means that CSI reporting based in measurements on TRS is not supported in NR.
TRS is configured via ‘trs-Info’ in the NZP-CSI-RS-ResourceSet IE of 3GPP Technical Specification (TS) 38.331 V16.6.0 which is associated with a CSI-RS resource set, for which the UE can assume that the antenna port with the same port index of the configured NZP CSI-RS resources in the said resource set is the same. From 3GPP specifications perspective, TRS is specified as a special kind of NZP CSI-RS where the corresponding NZP CSI-RS resource set containing the TRS(s) has a higher layer parameter ‘trs-info’ set to true.
TRS is not really a CSI-RS, rather it is a resource set consisting of multiple periodic NZP CSI-RS. More specifically, a TRS consists of four one-port, density-3 CSI-RSs located within two consecutive slots. The CSI-RS within the resource set can be configured with a periodicity of 10, 20, 40, or 80 milliseconds (ms). Note that the exact set of Res used for the TRS CSI-RS may vary. There is always a four-symbol time-domain separation between the two CSI-RS within a slot.
NR also supports aperiodic TRS.
For LTE, the Cell-Specific Reference Signal (CRS) served the same purpose as the TRS as LTE CRS can be used for synchronization but it can also be used for CSI reporting, which is not supported for TRS in NR. However, compared to the LTE CRS, the TRS implies much less overhead, only having one antenna port and only being present in two slots every TRS period.
In NR, a UE can be configured with multiple CSI reporting settings (also known as CSI-ReportConfig in 3GPP TS 38.331 V16.6.0) and multiple CSI-RS resource settings. Each CSI-RS resource setting can contain multiple resource sets, and each resource set can contain up to eight CSI-RS resources. For each CSI reporting setting, a UE feeds back a CSI report.
Each CSI reporting setting contains at least the following information:
Type I codebook (CB) is typically used by a UE to report CSI for Single User Multiple-Input Multiple-Output (SU-MIMO) scheduling in NR. While type II CB is typically for more accurate CSI feedback for MU-MIMO scheduling.
For both type I and type II CBS, for each rank, a precoding matrix W is defined in the form of
is a 2Nx2L matrix and contains information of L selected Discrete Fourier Transform (DFT) beams {di, i=1, . . . , L}, where di is a Nx1 DFT vector and N is the number of CSI-RS ports per polarization; while W2 is a 2L×ν matrix and contains the co-phasing coefficients between the selected beams and also between antenna ports with two different polarizations, where ν is the number of layers or rank. W1 is the same for the whole CSI bandwidth, while W2 can be for the whole bandwidth or per subband.
In case of type I CB, the precoding vector for each MIMO layer is associated with a single DFT beam. While for type II CB, the precoding vector for each layer is a linear combination of multiple DFT beams.
In NR Rel-16, type II CB is enhanced by applying Frequency Domain (FD) DFT basis across all subbands to reduced CSI feedback overhead and/or improve CSI accuracy. Instead of reporting W2 for each subband, linear combinations of DFT basis vectors are used to jointly represent W2 across the whole CSI bandwidth. For each layer, a precoding matrix W across all subbands is in the form of
W={tilde over (W)}1{tilde over (W)}2WfH
where Wf= [f1, . . . , fm] is a matrix containing M selected DFT basis vectors {f1, . . . , fm}, W2 is 2L×M matrix containing the co-phasing coefficients for each selected DFT beam and each selected FD basis vector, and W1 contains the selected DFT beams (i.e., in spatial domain.
Several signals can be transmitted from different antenna ports of a same base station. These signals can have the same large-scale properties such as Doppler shift/spread, average delay spread, or average delay. These antenna ports are then said to be Quasi Co-Located (QCL).
If the UE knows that two antenna ports are QCL with respect to a certain parameter (e.g., Doppler spread), the UE can estimate that parameter based on one of the antenna ports and apply that estimate for receiving signal on the other antenna port. Typically, the first antenna port is represented by a measurement reference signal such as TRS or Synchronization Signal Block (SSB) (known as source Reference Signal (RS)) and the second antenna port is a Demodulation Reference Signal (DMRS) (known as target RS).
For instance, if antenna ports A and B are QCL with respect to average delay, the UE can estimate the average delay from the signal received from antenna port A and assume that the signal received from antenna port B has the same average delay. This is useful for demodulation since the UE can know beforehand the properties of the channel, which for instance helps the UE in selecting an appropriate channel estimation filter.
Information about what assumptions can be made regarding QCL is signaled to the UE from the network. In NR, four types of QCL relations between a transmitted source RS and transmitted target RS were defined:
In NR, downlink beam management is performed by conveying spatial QCL (‘Type D’) assumptions to the UE through Transmission Configuration Indicator (TCI) states.
In NR Rel-15 or Rel-16, for Physical Downlink Control Channel (PDCCH), the network (NW) configures the UE with a set of PDCCH TCI states by Radio Resource Control (RRC), and then activates one TCI state per Control Resource Set (CORESET) using Medium Access Control (MAC) Control Element (CE). For Physical Downlink Shared Channel (PDSCH) beam management, the NW configures the UE with a set of PDSCH TCI states by RRC, and then activates up to 8 TCI states by MAC CE. After activation, the NW dynamically indicates one of these activated TCI states using a TCI field in Downlink Control Information (DCI) when scheduling PDSCH.
Such a framework allows great flexibility for the network to instruct the UE to receive signals from different spatial directions in the downlink with a cost of large signaling overhead and slow beam switch. These limitations are particularly noticeable and costly when UE movement is considered. One example is that beam update using DCI can only be performed for PDSCH, and MAC CE and/or RRC is required to update the beam for other reference signals/channels, with causes extra overhead and latency.
Furthermore, in majority of cases, the network transmits to and receives from a UE in the same direction for both data and control. Hence, using separate frameworks (TCI state respective spatial relations) for different channels/signals complicates the implementations.
In Rel-17, a common beam framework was introduced to simplify beam management in Frequency Range 2(FR2), in which a common beam represented by a TCI state may be activated/indicated to a UE and the common beam is applicable for multiple channels/signals such as PDCCH and PDSCH. The common beam framework is also referred to a unified TCI state framework.
The new framework can be RRC configured in one out two modes of operation, i.e., “Joint DL/UL TCI” or “Separate DL/UL TCI”. For “Joint DL/UL TCI”, one common Joint TCI state is used for both downlink (DL) and uplink (UL) signals/channels. For “Separate DL/UL TCI”, one common DL-only TCI state is used for DL channels/signals and one common UL-only TCI state is used for UL signals/channels.
A unified TCI state can be updated in a similar way as the TCI state update for PDSCH in Rel-15/16, i.e., with one of two alternatives:
The one activated or indicated unified TCI state will be used in subsequent PDCCH and PDSCH transmissions until a new unified TCI state is activated or indicated.
The existing DCI formats 1_1 and 1_2 are reused for beam indication, both with and without DL assignment. For DCI formats 1_1 and 1_2 with DL assignment, Acknowledgment (ACK)/Negative Acknowledgment (NACK) of the PDSCH can be used as indication of successful reception of beam indication. For DCI formats 1_1 and 1_2 without DL assignment, a new ACK/NACK mechanism analogous to that for Semi-Persistent Scheduling (SPS) PDSCH release with both type-1 and type-2 HARQ-ACK codebook is used, where upon a successful reception of the beam indication DCI, the UE reports an ACK.
For DCI-based beam indication, the first slot to apply the indicated TCI state is at least Y symbols after the last symbol of the acknowledgment of the joint or separate DL/UL beam indication. The Y symbols are configured by the next generation Node B (gNB) based on UE capability, which is also reported in units of symbols. The values of Y are yet not determined and is left to RAN4 to decide.
Systems and methods are disclosed for Channel State Information (CSI) Reference Signal (RS) reception and associated CSI reporting. In one embodiment, a method performed by a User Equipment (UE) comprises receiving, from a network node, first information that provides a CSI-RS configuration with a plurality of CSI-RS samples at different time instances and receiving, from the network node, second information that configures the UE (312) to report CSI feedback based on the CSI-RS configuration with the plurality of CSI-RS samples. The method further comprises computing at least one or more aspects of a precoding matrix for each CSI-RS sample of the plurality of CSI-RS samples, in accordance with the second information and reporting, to the network node, either the at least one or more aspects of the precoding matrix for each CSI-RS sample of the plurality of CSI-RS samples or information derived therefrom, via one or more CSI-RS reports. In this manner, performance under mobility scenarios can be improved.
In one embodiment, the plurality of CSI-RS samples are at different time instances within a single timeslot.
In one embodiment, the plurality of CSI-RS samples are at different time instances, the different time instances comprise at least one time instance in a first timeslot and at least one time instance in a second timeslot that is different than the first timeslot.
In one embodiment, the different times instances are either: different Orthogonal Frequency Division Multiplexing (OFDM) symbols within a single timeslot, or a same OFDM symbol in different timeslots, or different OFDM symbols in different timeslots.
In one embodiment, the first information comprises information that configures the plurality of CSI-RS samples as different Non-Zero Power (NZP) CSI-RS resources in a NZP CSI-RS resource set. In another embodiment, the first information comprises information that configures a plurality of NZP CSI-RS resources in a NZP CSI-RS resource set and a parameter that indicates that the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set are to be interpreted by the UE as the plurality of CSI-RS samples of a same NZP CSI-RS. In one embodiment, the plurality of CSI-RS samples are aperiodic. In one embodiment, the plurality of CSI-RS samples are triggered by a single trigger. In one embodiment, the number of CSI-RS samples in the plurality of CSI-RS samples is equal to the number of NZP CSI-RS resources in the NZP CSI-RS resource set.
In one embodiment, the first information further comprises information that explicitly or implicitly indicates a number of CSI-RS samples in the plurality of CSI-RS samples. In one embodiment, CSI-RS resource mappings for at least some of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set are different. In one embodiment, time-domain locations configured for at least some of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set are different. In one embodiment, the first information further comprises one or more common parameters that are common to all of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set.
In one embodiment, all of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set have a same number M of antenna ports. In one embodiment, the mth(m=0,1, . . . , M−1) antenna port for all of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set is the same.
In one embodiment, at least two of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set have different numbers of antenna ports.
In one embodiment, one NZP CSI-RS resource of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set has a first number of antenna ports and all remaining NZP CSI-RS resources of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set have a second number of antenna ports. In one embodiment, the second number of antenna ports is less than the first number of antenna ports. In another embodiment, the second number of antenna ports are associated with only a single polarization.
In one embodiment, the plurality of NZP CSI resources in the NZP CSI-RS resource set are periodic, and a same Transmission Configuration Indication (TCI) state identity (ID) is configured for all of the plurality of NZP-CSI resources in the NZP CSI-RS resource set.
In one embodiment, the plurality of NZP CSI resources in the NZP CSI-RS resource set are periodic, and a single parameter that indicates a TCI state identity ID configured for one of the plurality of NZP-CSI resources in the NZP CSI-RS resource set and is applicable to all of the plurality of NZP-CSI resources in the NZP CSI-RS resource set.
In one embodiment, the plurality of NZP CSI resources in the NZP CSI-RS resource set are periodic, and a single parameter that indicates a TCI state ID configured for all of the plurality of NZP CSI resources in the NZP CSI-RS resource set is comprised in an information element that defines the NZP CSI-RS resource set.
In one embodiment, the plurality of NZP-CSI resources in the NZP CSI-RS resource set are semi-persistent, and a same TCI state ID is configured for all of the plurality of NZP CSI resources in the NZP CSI-RS resource set via a Medium Access Control (MAC) Control Element (CE) that activates the NZP CSI-RS resource set.
In one embodiment, the plurality of NZP-CSI resources in the NZP CSI-RS resource set are semi-persistent, and a single TCI state ID is configured and applicable to of the plurality of NZP CSI resources in the NZP CSI-RS resource set via a MAC CE that activates the NZP CSI-RS resource set.
In one embodiment, the plurality of NZP CSI resources in the NZP CSI-RS resource set are semi-persistent, and a single parameter that indicates a TCI state ID configured for all of the plurality of NZP CSI resources in the NZP CSI-RS resource set is comprised in an information element that defines the NZP CSI-RS resource set.
In one embodiment, the plurality of NZP CSI resources in the NZP CSI-RS resource set are aperiodic, and a same TCI state ID is configured for all of the plurality of NZP CSI resources in the NZP CSI-RS resource set.
In one embodiment, the plurality of NZP CSI resources in the NZP CSI-RS resource set are aperiodic, and a single TCI state ID is configured for all of the plurality of NZ-CSI resources in the NZP CSI-RS resource set via an information element that defines the NZP CSI-RS resource set.
In one embodiment, a unified TCI state currently activated to the UE is applied to all of the plurality of NZP CSI resources in the NZP CSI-RS resource set.
In one embodiment, the first information comprises information that configures the plurality of CSI-RS samples via a configuration of a single NZP CSI-RS resource and information that defines a plurality of repetitions of the NZP CSI-RS resource which correspond to the plurality of CSI-RS samples. In one embodiment, the information that defines the plurality of repetitions of the NZP CSI-RS resource comprises information indicates one or more time offsets between repetitions of the NZP CSI-RS resource. In one embodiment, the plurality of repetitions of the NZP CSI-RS resource are within a single timeslot. In another embodiment, at least one first repetition of the plurality of repetitions of the NZP CSI-RS resource is within a first timeslot and at least one second repetition of the plurality of repetitions of the NZP CSI-RS resource is within a second timeslot.
In one embodiment, the CSI feedback is Type I CSI feedback, and, for each CSI-RS sample of the plurality of CSI-RS samples, the at least one or more aspects of the precoding matrix reported to the network node comprises a set of cophasing coefficients (W2).
In one embodiment, the CSI feedback is Type I CSI feedback, and the at least one or more aspects of the precoding matrix reported to the network node comprises a set of cophasing coefficient (W2) for one CSI-RS sample of the plurality of
CSI-RS samples, and, for each remaining CSI-RS sample of the plurality of CSI-RS samples, the at least one or more aspects of the precoding matrix reported to the network node comprises a phase difference of each coefficient of W2 for the remaining CSI-RS sample and a respective coefficient of W2 for the one CSI-RS sample. In one embodiment, for at least one CSI-RS sample of the plurality of CSI-RS samples, the at least one or more aspects of the precoding matrix reported to the network node comprises a matrix (W1) that contains information of one or more selected Discrete Fourier Transform (DFT) beams.
In one embodiment, the CSI feedback is Type II CSI feedback, and, for each CSI-RS sample of the plurality of CSI-RS samples, the at least one or more aspects of the precoding matrix reported to the network node comprises a set of cophasing coefficient (W2) and a selected set of Frequency Domain (FD) basis vectors.
In one embodiment, the CSI feedback is Type II CSI feedback. For one CSI-RS sample of the plurality of CSI-RS samples, the at least one or more aspects of the precoding matrix reported to the network node comprises a set of cophasing coefficient (W2) and a selected set of FD, basis vectors. For each remaining CSI-RS sample of the plurality of CSI-RS samples, the at least one or more aspects of the precoding matrix reported to the network node comprises a phase difference of each coefficient of W2 for the remaining CSI-RS sample and a respective coefficient of W2 for the one CSI-RS sample and a selected set of FD basis vectors. In one embodiment, for at least one CSI-RS sample of the plurality of CSI-RS samples, the at least one or more aspects of the precoding matrix reported to the network node comprises a matrix (W1) that contains information of one or more selected DFT beams.
Corresponding embodiments of a UE are also disclosed. In one embodiment, a UE comprises one or more transmitters, one or more receivers, and processing circuitry associated with the one or more transmitters and the one or more receivers. The processing circuitry is configured to cause the UE to receive, from a network node, first information that provides a CSI-RS configuration with a plurality of CSI-RS samples at different time instances, receive, from the network node, second information that configures the UE to report CSI feedback based on the CSI-RS configuration with the plurality of CSI-RS samples, compute at least one or more aspects of a precoding matrix for each CSI-RS sample of the plurality of CSI-RS samples, in accordance with the second information, and report, to the network node, either the at least one or more aspects of the precoding matrix for each CSI-RS sample of the plurality of CSI-RS samples or information derived therefrom, via one or more CSI-RS reports.
Embodiments of a method performed by a network node are also disclosed. In one embodiment, a method performed by a network comprises sending, to a UE, first information that provides a CSI-RS configuration with a plurality of CSI-RS samples at different time instances, sending, to the UE, second information that configures the UE to report CSI feedback based on the CSI-RS configuration with the plurality of CSI-RS samples at different times instances, and receiving, from the UE, either at least one or more aspects of the precoding matrix for each CSI-RS sample of the plurality of CSI-RS samples or information derived therefrom, via one or more CSI-RS reports.
Corresponding embodiments of a network node are also disclosed. In one embodiment, a network comprises processing circuitry configured to cause the network node to send, to a UE, first information that provides a CSI-RS configuration with a plurality of CSI-RS samples at different time instances, send, to the UE, second information that configures the UE to report CSI feedback based on the CSI-RS configuration with the plurality of CSI-RS samples at different times instances, and receive, from the UE, either at least one or more aspects of the precoding matrix for each CSI-RS sample of the plurality of CSI-RS samples or information derived therefrom, via one or more CSI-RS reports.
The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.
TRS symbols in two adjacent slots;
The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.
Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.
Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and/or is implied from the context in which it is used. All references to a/an/the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and/or where it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features, and advantages of the enclosed embodiments will be apparent from the following description.
Radio Node: As used herein, a “radio node” is either a radio access node or a wireless communication device.
Radio Access Node: As used herein, a “radio access node” or “radio network node” or “radio access network node” is any node in a Radio Access Network (RAN) of a cellular communications network that operates to wirelessly transmit and/or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), a relay node, a network node that implements part of the functionality of a base station (e.g., a network node that implements a gNB Central Unit (gNB-CU) or a network node that implements a gNB Distributed Unit (gNB-DU)) or a network node that implements part of the functionality of some other type of radio access node.
Core Network Node: As used herein, a “core network node” is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing an Access and Mobility Management Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.
Communication Device: As used herein, a “communication device” is any type of device that has access to an access network. Some examples of a communication device include, but are not limited to: mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or Personal Computer (PC). The communication device may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data via a wireless or wireline connection.
Wireless Communication Device: One type of communication device is a wireless communication device, which may be any type of wireless device that has access to (i.e., is served by) a wireless network (e.g., a cellular network). Some examples of a wireless communication device include, but are not limited to: a User Equipment device (UE) in a 3GPP network, a Machine Type Communication (MTC) device, and an Internet of Things (IoT) device. Such wireless communication devices may be, or may be integrated into, a mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or PC. The wireless communication device may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data via a wireless connection.
Network Node: As used herein, a “network node” is any node that is either part of the RAN or the core network of a cellular communications network/system.
Transmission/Reception Point (TRP): In some embodiments, a TRP may be either a network node, a radio head, a spatial relation, or a Transmission Configuration Indicator (TCI) state. A TRP may be represented by a spatial relation or a TCI state in some embodiments. In some embodiments, a TRP may be using multiple TCI states. In some embodiments, a TRP may a part of the gNB transmitting and receiving radio signals to/from UE according to physical layer properties and parameters inherent to that element. In some embodiments, in Multiple TRP (multi-TRP) operation, a serving cell can schedule UE from two TRPs, providing better Physical Downlink Shared Channel (PDSCH) coverage, reliability and/or data rates. There are two different operation modes for multi-TRP: single Downlink Control Information (DCI) and multi-DCI. For both modes, control of uplink and downlink operation is done by both physical layer and Medium Access Control (MAC). In single-DCI mode, UE is scheduled by the same DCI for both TRPs and in multi-DCI mode, UE is scheduled by independent DCIs from each TRP.
In some embodiments, a set Transmission Points (TPs) is a set of geographically co-located transmit antennas (e.g., an antenna array (with one or more antenna elements)) for one cell, part of one cell or one Positioning Reference Signal (PRS)-only TP. TPs can include base station (eNB) antennas, Remote Radio Heads (RRHs), a remote antenna of a base station, an antenna of a PRS-only TP, etc. One cell can be formed by one or multiple TPs. For a homogeneous deployment, each TP may correspond to one cell.
In some embodiments, a set of TRPs is a set of geographically co-located antennas (e.g., an antenna array (with one or more antenna elements)) supporting TP and/or Reception Point (RP) functionality.
Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system.
Note that, in the description herein, reference may be made to the term “cell”; however, particularly with respect to 5G NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.
There currently exist certain challenge(s). It is observed by measurements in real deployments that downlink Multi-User Multiple-Input Multiple-Output (MU-MIMO) precoding performance degrades when one or more of the co-scheduled UEs start to move faster than a few kilometers (km) per hour (km/h) relative to the base station. One of the main reasons is that the information of the channels, which is used to compute the Multiple-Input Multiple-Output (MIMO) precoding at the base station, becomes outdated rather quickly when this occurs. As a result, the precoder loses its effectiveness to protect co-scheduled UEs from interference when transmitting to an intended UE. Hence, downlink MU-MIMO precoding needs to be made robust to higher UE speeds.
It has been proposed and discussed in 3GPP pre-Release 18 scoping to extend Type-I or Type-II Channel State Information (CSI) feedback with time domain/Doppler information. However, the current CSI Reference Signal (CSI-RS) configuration is not suitable for deriving time domain/Doppler information as only a single CSI-RS sample is configured per resource within a CSI-RS periodicity in the current CSI-RS resource configuration. In order for the UE to compute time domain/Doppler information and feed it back as an extension of Type-I or Type-II CSI feedback, CSI-RS resource configuration with multiple samples is needed. How to configure the UE with such multiple sample CSI-RS is an open problem that needs to be solved.
Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges. Embodiments relating to two different alternative solutions are proposed for configuring multiple Non-Zero Power (NZP) CSI-RS samples. These solutions include the following solutions.
For Solution 1, embodiment of systems and methods are provided for configuring multiple NZP CSI-RS samples via configuring multiple NZP CSI-RS resources in a NZP CSI-RS resource set where each of the multiple NZP CSI-RS resources represents one NZP CSI-RS sample. These embodiments may include any one or more of the following aspects:
For Solution 2, embodiments of systems and methods are provided for configuring multiple NZP CSI-RS samples via configuring a single NZP CSI-RS resource, wherein a number of repetitions is associated with the single NZP CSI-RS resource and each repetition represents a single NZP CSI-RS sample. These embodiments may include one or more of the following aspects:
Certain embodiments may provide one or more of the following technical advantage(s). Embodiments of the proposed solutions enable CSI measurements on multiple NZP CSI-RS samples, e.g., to improve performance under mobility scenarios. Some of the embodiments provide specific ways of configuring multiple NZP CSI-RS samples with reduced configuration overhead (e.g., reduced Radio Resource Control (RRC) signaling overhead).
The base stations 302 and the low power nodes 306 provide service to wireless communication devices 312-1 through 312-5 in the corresponding cells 304 and 308. The wireless communication devices 312-1 through 312-5 are generally referred to herein collectively as wireless communication devices 312 and individually as wireless communication device 312. In the following description, the wireless communication devices 312 are oftentimes UEs, but the present disclosure is not limited thereto.
A description of embodiments of how multiple CSI-RS samples are used by the UE 312 to extend Type-I or Type-II codebook based CSI feedback with time domain/Doppler information is first provided. This is followed by detailed embodiments for configuring and signaling of CSI-RS with multiple samples.
First, let us assume that the UE 312 is configured for Type I CSI feedback based on the CSI-RS configuration with multiple samples. For each time instance, the UE 312 may compute the type I precoding matrix as
W(t)=W1(t)W2(t),t∈{t1,t2,t3}
Note that the selected Discrete Fourier Transform (DFT) beams change slowly when the time difference t3-t1 is small, i.e., W1(t1)≈W1(t2)≈W1(t3). Thus, in some embodiments, it is sufficient to compute and report one of W1(t1) and there is no need to compute and report W1(t2) and W1(t3). Stated in other words, for computing and reporting the selected DFT beams for Type I CSI feedback, it is sufficient to compute the selected DFT beams on one of the multiple samples of the CSI-RS (e.g., compute W1(t1) on t1 and report W1(t1)). However, as the co-phasing coefficients between selected beams change with different time instances, W2 needs to be computed and reported at each instance t1, t2, and t3(i.e., W2(t1), W2(t2), and W2(t3) computed at times t1, t2, and t3).
In one embodiment, W1(t1) and W2(t1) are reported in one reporting instance, while W2(t2) and W2(t3) are reported in separate reporting instances.
In another embodiment, W1(t1) and W2(t1) are reported in a first reporting instance, while W2(t2) and W2(t3) are jointly reported in a second reporting instances.
In yet another embodiment, W1(t1), W2(t1), W2(t2) and W2(t3) are reported jointly in a single reporting instance.
In the above embodiments, the reporting instances may be reported via either PUSCH or PUCCH.
In one example, with W2(t1), W2(t2), and W2(t3), the network (e.g., a network node such as a base station 302, e.g., a gNB) can derive the phase change for each W2 coefficient over time instances {t1, t2, t3} and thus estimate the underlying corresponding Doppler frequency or phase slope over the time period based on some criteria such as mean square error (MSE). An example phase slot for a coefficient of W2(t) is illustrated in
Alternatively, instead of reporting W2(t2) and W2(t3), the phase difference of each coefficient of W2 in different time instances with respect to the first time instance are reported. In a further embodiment, the phase slope of each coefficient of W2 over the time window is reported.
Now, let us assume that the UE 312 is configured for Type II CSI feedback based on the CSI-RS configuration with multiple samples. For each time instance, the UE 312 may compute the type II precoding matrix for each MIMO layer as
W(t)=W1(t)W2(t)WfH(t),t∈{t1,t2,t3}
Note that the selected DFT beams (i.e., in spatial domain) in W1(t) and the selected Frequency Domain (FD) basis vectors in Wf(t) change slowly when the time difference t3-t1 is small, i.e., W1(t1)≈W1(t2)≈W1(t3), and Wf(t1)≈Wf(t2)≈Wf(t3). Thus, in some embodiments, it is sufficient to compute and report W1(t1) and there is no need to compute and report W1(t2) and W1(t3). Stated in other words, for computing and reporting the selected DFT beams (i.e., in spatial domain) for Type II CSI feedback, it is sufficient to compute the selected DFT beams on the one of the multiple samples of the CSI-RS (e.g., compute W1(t1) on t1 and report W1(t1)). Similarly, it is sufficient to compute and report Wf(t1), and the UE 312 does not need to compute nor report Wf(t2) and Wf(t3). That is, for computing and reporting the selected FD basis vectors for enhanced type II CSI feedback, it is sufficient to compute the selected FD basis vectors on the one of the multiple samples of the CSI-RS (e.g., compute Wf(t1) on t1 and report Wf(t1)).
However, as the co-phasing coefficients between selected DFT beams (i.e., in spatial domain) and the selected FD basis vectors change with different time instances, W2 needs to be computed and reported at each instance t1, t2, and t3(i.e., W2(t1), W2(t2), and W2(t3) computed at times t1, t2, and t3).
In one embodiment, W1(t1), Wf(t1) and W2(t1) are reported in one reporting instance, while W2(t2) and W2(t3) are reported in separate reporting instances.
In another embodiment, W1(t1), Wf(t1) and W2(t1) are reported in a first reporting instance, while W2(t2) and W2(t3) are jointly reported in a second reporting instances.
In yet another embodiment, W1(t1), Wf(t1), W2(t1), W2(t2) and W2(t3) are reported jointly in a single reporting instance.
In the above embodiments, the reporting instances may be reported via either PUSCH or PUCCH.
With W2(t1), W2(t2) and W2(t3), the network (e.g., a network node such as a base station 302, e.g., a gNB) can derive the phase change for each W2 coefficient over time instances {t1, t2, t3} and thus estimate the underlying corresponding Doppler frequency or phase slope over the time period based on some criteria such as MSE. An example of phase slot for a coefficient of W2(t) is illustrated in
Alternatively, instead of reporting W2(t2) and W2(t3), the phase difference of each coefficient of W2 in different time instances with respect to the first time instance are reported. In a further embodiment, the phase slope of each coefficient of W2 over the time window is reported.
In one embodiment, the multiple samples are configured to the UE 312 as different NZP CSI-RS resources in a NZP CSI-RS resource set. To inform the UE 312 that the NZP CSI-RS resources configured in the NZP CSI-RS resource set correspond to different samples of the same NZP CSI-RS, a higher layer parameter can be configured to the UE 312, e.g., in the NZP-CSI-RS-ResourceSet information element (IE) (see 3GPP TS 38.331 V16.6.0 for definition of NZP-CSI-RS-ResourceSet IE). An example of such configuration is given in
The number of samples may also need to be configured to the UE 312. In some embodiments, the number of samples is always equal to the number of NZP CSI-RS resources in the configured NZP CSI-RS resource set. Then, the UE 312 can infer the number of samples from the configured NZP CSI-RS resource set, hence no explicit signaling is needed. In some other embodiments, the number of samples and/or the samples that should be used for CSI calculation may be explicitly signaled to the UE 312. This signaling can either be separately encoded, or jointly encoded with the high layer parameter for triggering the multi-sample CSI-RS. In some embodiments, explicitly signaled number of samples can be included as a higher layer parameter in the NZP-CSI-RS-ResourceSet IE.
In some embodiments, the CSI-RS resource mapping and/or the time domain location configured for each of the NZP CSI-RS resources in the NZP CSI-RS resource set are different. However, other parameters (for instance, except CSI-RS resource mapping and/or the time domain location) may be similar between the NZP CSI-RS resources in the NZP CSI-RS resource set. Hence, to save signaling overhead, these other parameters may not need to be signaled for each of the NZP CSI-RS resources.
In one embodiment, these other parameters are only configured for one of the NZP CSI-RS resources (e.g., the first NZP CSI-RS resource in the NZP CSI-RS resource set), and the UE interprets that these parameters apply to all the NZP CSI-RS resources in the NZP CSI-RS resource set when higher layer parameter “multisample-r18” is configured as ‘on’.
In another embodiment, all the NZP CSI-RS resources configured in the NZP CSI-RS resource set have the same number M of antenna ports (i.e., all the NZP CSI-RS resources in the NZP CSI-RS resource set are configured with the same value for higher layer parameter ‘nrofPorts’ as defined in 3GPP TS 38.331 V16.6.0). In this case, when the NZP CSI-RS resources in the NZP CSI-RS resource set are multiple samples of the same NZP CSI-RS, it means that the mth antenna port (m=0, 1, . . . , M−1) for all NZP CSI-RS resources in the NZP CSI-RS resource set is the same. This can be interpreted as the mth antenna port (m=0, 1, . . . , M−1) for all NZP CSI-RS resources in the NZP CSI-RS resource set being transmitted using any one of an antenna element, a subarray consisting of a group of antenna elements, or a beam. That is, the 1st antenna port for all NZP CSI-RS resources in the NZP CSI-RS resource set is the same, the 2nd antenna port for all NZP CSI-RS resources in the NZP CSI-RS resource set is the same, and so on. Note that the condition ‘same antenna port for all NZP CSI-RS resources in the NZP CSI-RS resource set’ shall be met for all M antenna ports.
In yet another embodiment, one of the NZP CSI-RS resources in the NZP CSI-RS resource set is configured with M1 antenna ports, and the remaining NZP CSI-RS resources in the NZP CSI-RS resource set are configured with a smaller number of M2 antenna ports where M2<M1. For example, the NZP CSI-RS resource with the larger number of ports may be the NZP CSI-RS resource that occurs earliest in time among the multiple NZP CSI-RS resources in the NZP CSI-RS resource set (e.g., the earliest NZP CSI-RS resource may correspond to the NZP CSI-RS resource at time t1 in
In another example, the M2 ports may be associated with only a single polarization, and the CSI-RS overhead can be reduced by roughly half. This could work since the time domain channel property, e.g., doppler, is common for both polarizations. In one variant of the embodiment, M2=1 in the above embodiments where multiple NZP CSI-RS resources except one NZP CSI-RS resource in the NZP CSI-RS resource set may be configured with single CSI-RS port. In this case, only one NZP CSI-RS resource in the resource set is configured with M1>1 CSI-RS ports.
In some embodiments, when the NZP CSI-RS resources in the NZP CSI-RS resource set are periodic, qcl-InfoPeriodicCSI-RS as defined in 3GPP TS 38.331 V16.6.0, which provides the TCI State ID related to the NZP CSI-RS, is configured to be the same for all NZP CSI-RS resources in the NZP CSI-RS resource set (i.e., the same value for the qcl-InfoPeriodicCSI-RS parameter is configured for all NZP CSI-RS resources in the NZP CSI-RS resource set).
In one embodiment, when the NZP CSI-RS resources are periodic, the parameter qcl-InfoPeriodicCSI-RS which provides the TCI State ID is only configured in the first NZP CSI-RS resource in the NZP CSI-RS resource set (the parameter qcl-InfoPeriodicCSI-RSis not configured in the remaining CSI-RS resources except the first NZP CSI-RS resource in the NZP CSI-RS resource set). Given the NZP CSI-RS resource set is configured for multi-sample CSI-RS (e.g., a flag ‘multisample-r18’ is configured to be ‘on’ or present in the NZP CSI-RS resource set), the UE interprets that the TCI state ID provided by the qcl-InfoPeriodicCSI-RS parameter configured in the first NZP CSI-RS resource in the NZP CSI-RS resource set should apply to the remaining NZP CSI-RS resources in the NZP CSI-RS resource set as well. A benefit of this embodiment is that qcl-InfoPeriodicCSI-RS does not have to be configured in all the NZP CSI-RS resources in the NZP CSI-RS resource set, thus saving higher layer signaling overhead.
In another embodiment, when the NZP CSI-RS resources are periodic, the parameter qcl-InfoPeriodicCSI-RS-r18 which provides the TCI State ID for the NZP CSI-RS resources in the NZP CSI-RS resource set is configured in the NZP-CSI-RS-ResourceSet IE as shown in
In some embodiments, when the NZP CSI-RS resources in the NZP CSI-RS resource set are semi-persistent, the same TCI State ID is indicated to all the NZP CSI-RS resources in a MAC CE that activates the semi-persistent NZP CSI-RS resource set. For instance, if there are/semi-persistent NZP CSI-RS resources in the semi-persistent NZP CSI-RS resource set, the MAC CE that activates the NZP CSI-RS resource set contains/VTCI State IDs set the same value (where each TCI state ID indicates the TCI state to be applied to each of the NNZP CSI-RS resources).
In another embodiment, when the NZP CSI-RS resources are semi-persistent, only a single TCI State ID is indicated in a MAC CE that activates the semi-persistent NZP CSI-RS resource set. The single TCI state ID provides the TCI State to be applied to all of the semi-persistent NZP CSI-RS resources in the semi-persistent NZP CSI-RS resource set. A benefit of this embodiment is that multiple TCI State IDs do not have to be signaled in the MAC CE that activates the semi-persistent NZP CSI-RS resource set, thus saving MAC CE signaling overhead.
In another embodiment, when the NZP CSI-RS resources are semi-persistent, a TCI state ID parameter which provides the TCI State ID for all the NZP CSI-RS resources in the NZP CSI-RS resource set is configured in the NZP-CSI-RS-ResourceSet IE (similar to qcl-InfoPeriodicCSI-RS-r18 parameter shown in
In some embodiments, when the NZP CSI-RS resources in the NZP CSI-RS resource set are aperiodic, the same TCI State ID is indicated to all the NZP CSI-RS resources in the aperiodic NZP CSI-RS resource set. When an uplink DCI triggers an aperiodic CSI-RS resource set, a codepoint in the ‘CSI request field’ in the uplink DCI will point to one CSI-AperiodicTriggerState as specified in the CSI-AperiodicTriggerStateList IE in 3GPP TS 38.331 V16.6.0. Each CSI-AperiodicTriggerState will trigger an CSI-AssociatedReportConfigInfo which contains an NZP CSI-RS resource set for channel measurement. When the NZP CSI-RS resource set is aperiodic and the NZP CSI-RS resource set is configured for multi-sample CSI-RS (e.g., a flag ‘multisample-r18’ is configured to be ‘on’ or present in the NZP CSI-RS resource set), then in some embodiments a single TCI state ID is provided as part of CSI-AssociatedReportConfigInfo which should be applied to all the aperiodic NZP CSI-RS resources in the NZP CSI-RS resource set. An example is shown in
In another embodiment, when the NZP CSI-RS resources are aperiodic, a TCI state ID parameter which provides the TCI State ID for all the NZP CSI-RS resources in the NZP CSI-RS resource set is configured in the NZP-CSI-RS-ResourceSet IE (similar to qcl-InfoPeriodicCSI-RS-r18 parameter shown in
In another embodiment, when the NZP CSI-RS resources in the NZP CSI-RS resource set are periodic/semi-persistent/aperiodic, the unified TCI state currently activated to the UE 312 (either “Joint DL/UL TCI state” or DL TCI state) is applied to all NZP CSI-RS resources in the NZP CSI-RS resource set.
3.6 Differences from Prior Solutions
It should be noted that the embodiments proposed above are different from the case when parameter ‘trs-info’ is configured to ‘true’ in the NZP CSI-RS Resource set. When ‘trs-info’ is configured to true in the NZP CSI-RS resource set, the NZP CSI-RS resources in the NZP CSI-RS resource set (which are tracking reference signals or TRSs) can be used by the UE to derive time domain channel properties such as Doppler shift, Doppler spread, etc. However, up to NR Release-17, the UE does not report any CSI on the TRS resources. Using the solutions proposed herein, the UE 312 can perform Precoding Matrix Indicator (PMI) computations corresponding to extended Type-I or Type-II CSI as described in Sections 1 and 2 above using the multi-sample NZP CSI-RS, and can report the computed extended Type-I or Type-II CSI to the network. In addition to PMI, the extended Type-I or Type-II CSI may include one or more of Rank Indicator (RI), Layer Indicator (LI), and Channel Quality Indicator (CQI). Another difference is that TRS only allows measurements on a single antenna port while the solutions proposed herein allow multi-sample measurements on NZP CSI-RS for M>1 antenna ports.
Furthermore, the embodiments proposed above are also different from the case when parameter ‘repetition’ is configured to ‘on’ in the NZP CSI-RS resource set. When parameter ‘repetition’ is configured to ‘on’, the NZP CSI-RS resources in the NZP CSI-RS resource sets can be used by the UE to measure and report Layer 1 RSRP (L1-RSRP) or Layer 1 (L1-SINR). However, the solutions proposed herein allow the UE to perform PMI computations corresponding to extended Type-I or Type-II CSI as described above.
4 Indication of Multiple CSI-RS Samples via Indicating Offsets Associated with Multiple CSI-RS Samples
In one embodiment, only a single NZP CSI-RS resource may be configured in a NZP CSI-RS resource set. The CSI-RS resource may be repeated within a slot when triggered. The repetition may be either configured in the CSI report configuration, dynamically indicated in DCI triggering the CSI report, or activated by a MAC CE that activates the CSI report. Note that in these embodiments the different repetitions represent the different samples of the NZP CSI-RS. The number of repetitions may be pre-specified, e.g., fixed to 2 repetitions. Alternatively, the number of repetitions may be linked to the number of CSI-RS ports in the CSI-RS resource. For example, for 16 or 32 CSI-RS ports, the number of repetitions are fixed to 2. For 8 CSI-RS ports, the number of repetitions may be more than 2, e.g., 3 or 4 and one of them may be either configured or dynamically indicated in the DCI. A gap in number of OFDM symbols may also be configured between two repetitions. An example is shown in
In an alternative embodiment, assuming N repetitions (i.e., samples) of NZP CSI-RS in the slot, an alternative way may be to signal the time domain offsets (in symbols) corresponding to the remaining N-1 samples with respect to the first sample.
In some embodiments, multiple gap sizes may be signaled to the UE 312 by the network in order to support the use case where the multiple NZP CSI-RS samples are non-uniformly spaced. Considering the example shown in
In another embodiment, a single gap size may be signaled to the UE 312 by the network in order to support the use case where the multiple NZP CSI-RS samples are uniformly spaced. In this embodiment, referring to the example shown in
In some embodiments, for a single NZP CSI-RS resource, the firstOFDMSymbolInTimeDomain and firstOFDMSymbolInTimeDomain2 in the CSI-RS-ResourceMapping (as defined in 3GPP TS 38.331 V16.6.0) associated with the NZP CSI-RS resource provides the time domain symbols for the first NZP CSI-RS repetition (or first NZP CSI-RS sample) within the slot. The time domain location for the second NZP CSI-RS sample is determined by offsetting the firstOFDMSymbolIn TimeDomain and firstOFDMSymbolInTimeDomain2 by the sample gap size between the first NZP CSI-RS sample and the second NZP CSI-RS sample (i.e., time domain location for the second NZP CSI-RS sample determined by firstOFDMSymbolInTimeDomain+g1 and firstOFDMSymbolInTimeDomain2+g1 where g1 is the sample gap size between the first and the second NZP CSI-RS samples).
The time domain location for the third NZP CSI-RS sample is determined by offsetting the firstOFDMSymbolInTimeDomain and firstOFDMSymbolInTimeDomain2 by the sample gap sizes between the first NZP CSI-RS sample and the second NZP CSI-RS sample, and between the second NZP CSI-RS sample and the third NZP CSI-RS sample (i.e., time domain location for the third NZP CSI-RS sample determined by firstOFDMSymbolInTimeDomain+g1+g2 and firstOFDMSymbolInTimeDomain2+g1+g2 where g1 is the sample gap size between the first and the second NZP CSI-RS samples, g1 is the sample gap size between the second and the third NZP CSI-RS samples).
In another embodiment, a CSI-RS resource may be repeated across slots when triggered. The repetition may be either configured in the corresponding CSI report configuration, dynamically indicated in DCI triggering the CSI report, or indicated via a MAC CE activating the CSI report. The number of repetitions may be pre-specified, e.g., fixed to 2 repetitions. Alternatively, the number of repetitions may be dynamically indicated in the DCI, or indicated via a MAC CE. The same time and frequency resource is used in each of the repeated slots for the CSI-RS resource. An example is shown in
In some embodiments, the configured/indicated/signaled number of repetitions (i.e., samples) are received in adjacent slots. In this embodiment, if the time/frequency resource allocation for a particular NZP CSI-RS sample in a particular slot collides with an SSB or at least one uplink symbol, then that particular NZP CSI-RS sample is dropped, and CSI is not measured using that NZP CSI-RS sample.
In another embodiment, the configured/indicated/signaled number of NZP CSI-RS repetitions (i.e., samples) are received in non-adjacent slots. Which slots should carry the different number of NZP CSI-RS repetitions may be indicated in different ways. For instance, a bit map of a predefined length may be used for this purpose. In this bitmap, each bit indicates whether a NZP CSI-RS sample is present in a particular slot or not. A bit value of 1 may indicate that a NZP CSI-RS sample is present in that particular slot. Alternatively, one or more gap sizes between different samples may be configured to indicate which slots contain a NZP CSI-RS sample.
In a further embodiment, both intra-slot and inter-slot repetitions may be configured for a CSI-RS resource associated with a CSI report.
To ensure correct CSI measurement, phase continuity among the CSI-RS repetitions within a slot or across slots is needed.
Periodic or semi-persistent CSI-RS can be configured to the UE 312. The benefit is that the same CSI-RS can be shared among multiple UEs to save the CSI-RS overhead. In this case, the UE 312 needs to determine which samples are to be used for CSI calculation. In some embodiments, the UE 312 is configured explicitly by the network (e.g., network node such as a base station, e.g., gNB) with which samples to use for CSI calculation. For example, such configuration can explicitly indicate the time domain locations of CSI-RS samples to be used. In some other embodiments, the UE 312 can be configured with the number of samples to use. The above configurations can either be configured in the corresponding CSI report configuration or dynamically indicated in DCI triggering the CSI report.
As illustrated, the network node 1400 provides, to the UE 312, first information that provides a CSI-RS configuration with a plurality of CSI-RS samples at different time instances (step 1402). As described above, in one embodiment (“Embodiment A”), step 1402 includes the network node 1400 providing, to the UE 312, an indication of multiple CSI-RS samples (e.g., indicated as multiple NZP CSI-RS resources in a NZP CSI-RS resource set), e.g., via higher layer parameter (e.g., a parameter that indicates to the UE 312 that the UE 312 is to interpret the multiple NZP CSI-RS resources in the NZP CSI-RS resource set as the multiple CSI-RS samples of the same CSI-RS) (step 1402A-1). In addition, the network node 1400 may provide, to the UE 312, an explicit or implicit indication of the number of CSI-RS samples (step 1402A-2). The network node 1400 may provide information that indicates a TCI state ID for the CSI-RS samples (step 1402A-3). Further details regarding steps 1402A-1, 1402A-2, and 1402A-3 and associated embodiments can be found, e.g., in Section 3 above. Those details are equally applicable here.
Alternatively, in another embodiment (“Embodiment B”) of step 1402, the network node 1400 provides, to the UE 312, an indication of the multiple CSI-RS samples via providing information that indicates multiple repetitions of a single NZP CSI-RS resource (e.g., via indicating time offset(s) or time gap(s) between the multiple repetitions of the single NZP CSI-RS resource) (step 1402B-1). Alternatively, the repetitions of the single NZP CSI-RS resource may be indicated via a CSI report configuration, dynamically (e.g., via DCI triggering CSI report), or indicated via MAC CE, or the like. Further details regarding step 1402B-1 and associated embodiments can be found, e.g., in Section 4 above. Those details are equally applicable here.
It should also be noted that the information provided to the UE 312 in step 1402 may be sent via one or more messages using one or more signaling types (e.g., RRC, MAC, DCI, or combination of any two or more thereof).
The network node 1400 sends, to the UE 312, second information (e.g., a CSI report configuration) that configures the UE to report CSI feedback (e.g., Type I or Type II) based on the CSI-RS configuration with multiple CSI-RS samples (step 1404). The UE 312 computes at least some aspect(s) of a precoding matrix for each CSI-RS sample (step 1406) and reports this information or information derived therefrom via one or more CSI-RS reports (step 1408), in accordance with the configuration of step 1404. Details of what information is computed and reported can be found above, e.g., in Section 1(Type I) and Section 2(Type II). Those details are equally applicable here.
The network node 1400 may then perform one or more operational tasks based on the CSI report(s) (step 1410). For example, the network node 1400 may utilize this information for downlink MU-MIMO precoding.
As used herein, a “virtualized” radio access node is an implementation of the radio access node 1500 in which at least a portion of the functionality of the radio access node 1500 is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the radio access node 1500 may include the control system 1502 and/or the one or more radio units 1510, as described above. The control system 1502 may be connected to the radio unit(s) 1510 via, for example, an optical cable or the like. The radio access node 1500 includes one or more processing nodes 1600 coupled to or included as part of a network(s) 1602. If present, the control system 1502 or the radio unit(s) are connected to the processing node(s) 1600 via the network 1602. Each processing node 1600 includes one or more processors 1604 (e.g., CPUs, ASICs, FPGAS, and/or the like), memory 1606, and a network interface 1608.
In this example, functions 1610 of the radio access node 1500 described herein are implemented at the one or more processing nodes 1600 or distributed across the one or more processing nodes 1600 and the control system 1502 and/or the radio unit(s) 1510 in any desired manner. In some particular embodiments, some or all of the functions 1610 of the radio access node 1500 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) 1600. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) 1600 and the control system 1502 is used in order to carry out at least some of the desired functions 1610. Notably, in some embodiments, the control system 1502 may not be included, in which case the radio unit(s) 1510 communicate directly with the processing node(s) 1600 via an appropriate network interface(s).
In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of radio access node 1500 or a node (e.g., a processing node 1600) implementing one or more of the functions 1610 of the radio access node 1500 in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).
In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the wireless communication device 1800 according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).
With reference to
The telecommunication network 2000 is itself connected to a host computer 2016, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server, or as processing resources in a server farm. The host computer 2016 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. Connections 2018 and 2020 between the telecommunication network 2000 and the host computer 2016 may extend directly from the core network 2004 to the host computer 2016 or may go via an optional intermediate network 2022. The intermediate network 2022 may be one of, or a combination of more than one of, a public, private, or hosted network; the intermediate network 2022, if any, may be a backbone network or the Internet; in particular, the intermediate network 2022 may comprise two or more sub-networks (not shown).
The communication system of
Example implementations, in accordance with an embodiment, of the UE, base station, and host computer discussed in the preceding paragraphs will now be described with reference to
The communication system 2100 further includes a base station 2118 provided in a telecommunication system and comprising hardware 2120 enabling it to communicate with the host computer 2102 and with the UE 2114. The hardware 2120 may include a communication interface 2122 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 2100, as well as a radio interface 2124 for setting up and maintaining at least a wireless connection 2126 with the UE 2114 located in a coverage area (not shown in
The communication system 2100 further includes the UE 2114 already referred to. The UE's 2114 hardware 2134 may include a radio interface 2136 configured to set up and maintain a wireless connection 2126 with a base station serving a coverage area in which the UE 2114 is currently located. The hardware 2134 of the UE 2114 further includes processing circuitry 2138, which may comprise one or more programmable processors, ASICS, FPGAs, or combinations of these (not shown) adapted to execute instructions. The UE 2114 further comprises software 2140, which is stored in or accessible by the UE 2114 and executable by the processing circuitry 2138. The software 2140 includes a client application 2142. The client application 2142 may be operable to provide a service to a human or non-human user via the UE 2114, with the support of the host computer 2102. In the host computer 2102, the executing host application 2112 may communicate with the executing client application 2142 via the OTT connection 2116 terminating at the UE 2114 and the host computer 2102. In providing the service to the user, the client application 2142 may receive request data from the host application 2112 and provide user data in response to the request data. The OTT connection 2116 may transfer both the request data and the user data. The client application 2142 may interact with the user to generate the user data that it provides.
It is noted that the host computer 2102, the base station 2118, and the UE 2114 illustrated in
In
The wireless connection 2126 between the UE 2114 and the base station 2118 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the UE 2114 using the OTT connection 2116, in which the wireless connection 2126 forms the last segment.
A measurement procedure may be provided for the purpose of monitoring data rate, latency, and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 2116 between the host computer 2102 and the UE 2114, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection 2116 may be implemented in the software 2110 and the hardware 2104 of the host computer 2102 or in the software 2140 and the hardware 2134 of the UE 2114, or both. In some embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 2116 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which the software 2110, 2140 may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 2116 may include message format, retransmission settings, preferred routing, etc.; the reconfiguring need not affect the base station 2118, and it may be unknown or imperceptible to the base station 2118. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling facilitating the host computer 2102's measurements of throughput, propagation times, latency, and the like. The measurements may be implemented in that the software 2110 and 2140 causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 2116 while it monitors propagation times, errors, etc.
Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according one or more embodiments of the present disclosure.
While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).
Some example embodiments of the present disclosure are as follows:
Embodiment 1: A method performed by a User Equipment, UE, (312), the method comprising one or more of the following:
Embodiment 2: The method of embodiment 1 wherein the plurality of CSI-RS samples are at different time instances within a single timeslot or slot (also denoted as “timeslot/slot”).
Embodiment 3: The method of embodiment 1 wherein the plurality of CSI-RS samples are at different time instances, the different time instances comprising at least one time instance in a first timeslot/slot and at least one time instance in a second timeslot/slot that is different than the first timeslot/slot.
Embodiment 4: The method of any of embodiments 1 to 3 wherein the different times instances are (1) different Orthogonal Frequency Division Multiplexing, OFDM, symbols within a single timeslot/slot, or (2) same or different OFDM symbols in different timeslot/slot.
Embodiment 5: The method of any of embodiments 1 to 4 wherein the first information comprises information that configures the plurality of CSI-RS samples as different NZP CSI-RS resources in a NZP CSI-RS resource set.
Embodiment 6: The method of any of embodiments 1 to 4 wherein the first information comprises information that configures: a plurality NZP CSI-RS resources in a NZP CSI-RS resource set; and a parameter that indicates that the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set are to be interpreted by the UE (312) as the plurality of CSI-RS samples of a same NZP CSI-RS.
Embodiment 7: The method of any of embodiments 5 to 6 wherein the first information further comprises information that explicitly or implicitly indicates a number of CSI-RS samples in the plurality of CSI-RS samples.
Embodiment 8: The method of any of embodiments 5 to 7 wherein CSI-RS resource mappings for at least some of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set are different.
Embodiment 9: The method of any of embodiments 5 to 8 wherein time-domain locations configured for at least some of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set are different.
Embodiment 10: The method of any of embodiments 5 to 9 wherein the first information further comprises one or more common parameters that are common to all of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set.
Embodiment 11: The method of any of embodiments 5 to 10 wherein all of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set have a same number of antenna ports.
Embodiment 12: The method of any of embodiments 5 to 10 wherein at least two of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set have different numbers of antenna ports.
Embodiment 13: The method of any of embodiments 5 to 10 wherein one NZP CSI-RS resource of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set has a first number of antenna ports and all remaining NZP CSI-RS resources of the plurality of NZP CSI-RS resources in the NZP CSI-RS resource set have a second number of antenna ports.
Embodiment 14: The method of embodiment 13 wherein the second number of antenna ports is less than the first number of antenna ports.
Embodiment 15: The method of embodiment 13 or 14 wherein the second number of antenna ports are associated with only a single polarization.
Embodiment 16: The method of any of embodiments 5 to 15 wherein the plurality of NZP-CSI resources in the NZP CSI-RS resource set are periodic, and a same TCI state ID is configured for all of the plurality of NZP-CSI resources in the NZP CSI-RS resource set.
Embodiment 17: The method of any of embodiments 5 to 15 wherein the plurality of NZP-CSI resources in the NZP CSI-RS resource set are periodic, and a single parameter that indicates a TCI state ID configured for one of the plurality of NZP-CSI resources in the NZP CSI-RS resource set and is applicable to all of the plurality of NZP-CSI resources in the NZP CSI-RS resource set.
Embodiment 18: The method of any of embodiments 5 to 15 wherein the plurality of NZP-CSI resources in the NZP CSI-RS resource set are periodic, and a single parameter that indicates a TCI state ID configured for all of the plurality of NZP-CSI resources in the NZP CSI-RS resource set is comprised in an information element that defines the NZP CSI-RS resource set.
Embodiment 19: The method of any of embodiments 5 to 15 wherein the plurality of NZP-CSI resources in the NZP CSI-RS resource set are semi-persistent, and a same TCI state ID is configured for all of the plurality of NZP-CSI resources in the NZP CSI-RS resource set via a MAC CE that activates the NZP CSI-RS resource set.
Embodiment 20: The method of any of embodiments 5 to 15 wherein the plurality of NZP-CSI resources in the NZP CSI-RS resource set are semi-persistent, and a single TCI state ID is configured and applicable to of the plurality of NZP-CSI resources in the NZP CSI-RS resource set via a MAC CE that activates the NZP CSI-RS resource set.
Embodiment 21: The method of any of embodiments 5 to 15 wherein the plurality of NZP-CSI resources in the NZP CSI-RS resource set are semi-persistent, and a single parameter that indicates a TCI state ID configured for all of the plurality of NZP-CSI resources in the NZP CSI-RS resource set is comprised in an information element that defines the NZP CSI-RS resource set.
Embodiment 22: The method of any of embodiments 5 to 15 wherein the plurality of NZP-CSI resources in the NZP CSI-RS resource set are aperiodic, and a same TCI state ID is configured for all of the plurality of NZP-CSI resources in the NZP CSI-RS resource set.
Embodiment 23: The method of any of embodiments 5 to 15 wherein the plurality of NZP-CSI resources in the NZP CSI-RS resource set are aperiodic, and a single TCI state ID is configured for all of the plurality of NZP-CSI resources in the NZP CSI-RS resource set via an information element that defines the NZP CSI-RS resource set
Embodiment 24: The method of any of embodiments 5 to 15 wherein a unified TCI state currently activated to the UE (312) is applied to all of the plurality of NZP-CSI resources in the NZP CSI-RS resource set.
Embodiment 25: The method of any of embodiments 1 to 4 wherein the first information comprises information that configures the plurality of CSI-RS samples via a configuration of a single NZP CSI-RS resource and information that defines a plurality of repetitions of the NZP CSI-RS resource which correspond to the plurality of CSI-RS samples.
Embodiment 26: The method of embodiment 25 wherein the information that defines the plurality of repetitions of the NZP CSI-RS resource comprises information indicates one or more time offsets or time gaps between repetitions of the NZP CSI-RS resource.
Embodiment 27: The method of embodiment 25 or 26 wherein the plurality of repetitions of the NZP CSI-RS resource are within a single timeslot/slot.
Embodiment 28: The method of embodiment 25 or 26 wherein at least one first repetition of the plurality of repetitions of the NZP CSI-RS resource is within a first timeslot/slot and at least one second repetition of the plurality of repetitions of the NZP
CSI-RS resource is within a second timeslot/slot.
Embodiment 29: The method of any of embodiments 1 to 28 wherein the CSI feedback is Type I CSI feedback, and, for each CSI-RS sample of the plurality of CSI-RS samples, the at least some aspect(s) of the precoding matrix reported to the network node comprises a set of cophasing coefficients (W2).
Embodiment 30: The method of any of embodiments 1 to 28 wherein the CSI feedback is Type I CSI feedback, and:
Embodiment 31: The method of embodiments 29 or 30 wherein, for at least one CSI-RS sample of the plurality of CSI-RS samples, the at least some aspect(s) of the precoding matrix reported to the network node comprises a matrix (W1) of size 2Nx2L that contains information of L selected DFT beams.
Embodiment 32: The method of any of embodiments 1 to 28 wherein the CSI feedback is Type II CSI feedback, and, for each CSI-RS sample of the plurality of CSI-RS samples, the at least some aspect(s) of the precoding matrix reported to the network node comprises a set of cophasing coefficient (W2) and a selected set of FD bases vectors.
Embodiment 33: The method of any of embodiments 1 to 28 wherein the CSI feedback is Type II CSI feedback, and:
Embodiment 34: The method of embodiments 32 or 33 wherein, for at least one CSI-RS sample of the plurality of CSI-RS samples, the at least some aspect(s) of the precoding matrix reported to the network node comprises a matrix (W1) of size 2Nx2L that contains information of L selected DFT beams.
Embodiment 35: The method of any of the previous embodiments, further comprising: providing user data; and forwarding the user data to a host computer via the transmission to the base station.
Embodiment 36: A method performed by a network node (1400), the method comprising:
Embodiment 37: The method of any of the previous embodiments, further comprising: obtaining user data; and forwarding the user data to a host computer or a wireless device.
Embodiment 38: A wireless device comprising:
Embodiment 39: A base station comprising:
Embodiment 40: A User Equipment, UE, comprising:
Embodiment 41: A communication system including a host computer comprising:
Embodiment 42: The communication system of the previous embodiment further including the base station.
Embodiment 43: The communication system of the previous 2 embodiments, further including the UE, wherein the UE is configured to communicate with the base station.
Embodiment 44: The communication system of the previous 3 embodiments, wherein:
Embodiment 45: A method implemented in a communication system including a host computer, a base station, and a User Equipment, UE, the method comprising:
Embodiment 46: The method of the previous embodiment, further comprising, at the base station, transmitting the user data.
Embodiment 47: The method of the previous 2 embodiments, wherein the user data is provided at the host computer by executing a host application, the method further comprising, at the UE, executing a client application associated with the host application.
Embodiment 48: A User Equipment, UE, configured to communicate with a base station, the UE comprising a radio interface and processing circuitry configured to perform the method of the previous 3 embodiments.
Embodiment 49: A communication system including a host computer comprising:
Embodiment 50: The communication system of the previous embodiment, wherein the cellular network further includes a base station configured to communicate with the UE.
Embodiment 51: The communication system of the previous 2 embodiments, wherein:
Embodiment 52: A method implemented in a communication system including a host computer, a base station, and a User Equipment, UE, the method comprising:
Embodiment 53: The method of the previous embodiment, further comprising at the UE, receiving the user data from the base station.
Embodiment 54: A communication system including a host computer comprising:
Embodiment 55: The communication system of the previous embodiment, further including the UE.
Embodiment 56: The communication system of the previous 2 embodiments, further including the base station, wherein the base station comprises a radio interface configured to communicate with the UE and a communication interface configured to forward to the host computer the user data carried by a transmission from the UE to the base station.
Embodiment 57: The communication system of the previous 3 embodiments, wherein:
Embodiment 58: The communication system of the previous 4 embodiments, wherein:
Embodiment 59: A method implemented in a communication system including a host computer, a base station, and a User Equipment, UE, the method comprising: at the host computer, receiving user data transmitted to the base station from the UE, wherein the UE performs any of the steps of any of the Group A embodiments.
Embodiment 60: The method of the previous embodiment, further comprising, at the UE, providing the user data to the base station.
Embodiment 61: The method of the previous 2 embodiments, further comprising:
Embodiment 62: The method of the previous 3 embodiments, further comprising:
Embodiment 63: A communication system including a host computer comprising a communication interface configured to receive user data originating from a transmission from a User Equipment, UE, to a base station, wherein the base station comprises a radio interface and processing circuitry, the base station's processing circuitry configured to perform any of the steps of any of the Group B embodiments.
Embodiment 64: The communication system of the previous embodiment further including the base station.
Embodiment 65: The communication system of the previous 2 embodiments, further including the UE, wherein the UE is configured to communicate with the base station.
Embodiment 66: The communication system of the previous 3 embodiments, wherein:
Embodiment 67: A method implemented in a communication system including a host computer, a base station, and a User Equipment, UE, the method comprising: at the host computer, receiving, from the base station, user data originating from a transmission which the base station has received from the UE, wherein the UE performs any of the steps of any of the Group A embodiments.
Embodiment 68: The method of the previous embodiment, further comprising at the base station, receiving the user data from the UE.
Embodiment 69: The method of the previous 2 embodiments, further comprising at the base station, initiating a transmission of the received user data to the host computer.
Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.
This application claims the benefit of provisional patent application Ser. No. 63/307,524, filed Feb. 7, 2022, the disclosure of which is hereby incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2023/051088 | 2/7/2023 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63307524 | Feb 2022 | US |
