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EP-4740317-A1 - METHODS AND DEVICES FOR CSI OMISSION WHEN REPORTING MULTIPLE CSI SUB-CONFIGURATIONS

EP4740317A1EP 4740317 A1EP4740317 A1EP 4740317A1EP-4740317-A1

Abstract

Methods and devices in a wireless network provide omission techniques for CSI reports based on a CSI report configuration including multiple CSI report sub-configurations. A wireless communication method (400) performed by a UE includes determining (440), based on sub-configuration priority levels associated with the multiple CSI report sub-configurations, a subset of the CSI components to omit from at least one CSI report prepared according to the CSI report configuration. A network entity receiving the at least one CSI report, similarly determines based on sub-configuration priority levels associated with the multiple CSI report sub-configurations, the subset of the CSI components omitted from at least one CSI report prepared according to the CSI report configuration.

Inventors

  • ZHANG, YUSHU

Assignees

  • Google LLC

Dates

Publication Date
20260513
Application Date
20230810

Claims (16)

  1. A wireless communication method (400) for channel state information, CSI, omission performed by a user equipment, UE, the method comprising: receiving (434) a first control signal conveying at least one CSI reference signal, CSI-RS, resource and a CSI report configuration including multiple CSI report sub-configurations; receiving (438) a CSI-RS on the at least one CSI-RS resource to evaluate CSI components corresponding to the multiple CSI report sub-configurations; determining (440) , based on sub-configuration priority levels associated with the multiple CSI report sub-configurations, a subset of the CSI components to omit from at least one CSI report prepared according to the CSI report configuration; and transmitting (442) the at least one CSI report.
  2. The wireless communication method of claim 1, wherein the sub-configuration priority levels depend on at least one of: report sub-configuration identifiers of the multiple CSI report sub-configurations, number of antenna ports for sub-configuration-related codebooks, or power offsets between the CSI-RS and a physical downlink shared channel.
  3. The wireless communication method of claim 2, further comprising: when a first sub-configuration priority level of a first CSI report sub-configuration is equal to a second sub-configuration priority level of a second CSI report sub-configuration, the first sub-configuration priority level and the second sub-configuration priority level being based on one of the report sub-configuration identifiers, the number of antenna ports, or the power offsets, using another one of the report sub-configuration identifiers, the number of antenna ports, or the power offsets to differentiate the first sub-configuration priority level from the second sub-configuration priority level.
  4. The wireless communication method of any of claims 1 to 3, further comprising: receiving a second control signal that triggers reporting the CSI components corresponding to one or more of the multiple CSI report sub-configurations.
  5. The wireless communication method of any of claims 1 to 4, further comprising: transmitting a UE capability control signal specifying a UE capability to omit the subset of the CSI components from the at least one CSI report, the UE capability control signal conveying at least one of: a maximum number of CSI report sub-configurations per CSI report configuration, a maximum number of configured CSI report sub-configurations across CSI report configurations per component carrier, CC, frequency band, or band combination, a maximum number of reported CSI report sub-configurations per CSI report configuration in a slot, or a maximum number of reported CSI report sub-configurations across CSI report configurations per CC, frequency band, or band combination in the slot.
  6. The wireless communication method of any of claims 1 to 5, further comprising: including, in the subset of the CSI components to omit from the at least one CSI report, a non-reported CSI sub-configuration associated with a lower sub-configuration priority level than one or more reported CSI sub-configurations among the multiple CSI report sub-configurations; and preparing individual CSI reports for the reported CSI sub-configurations, wherein the transmitting of the at least one CSI report includes transmitting the individual CSI reports.
  7. The wireless communication method of any of claims 1 to 6, the method further comprising: calculating the sub-configuration priority levels, each sub-configuration priority level being based on a configuration priority value, a report sub-configuration identifier, and a maximum number of CSI report sub-configurations in the CSI report configuration.
  8. The wireless communication method of any of claims 1 to 5, further comprising: including, in the subset of the CSI components to omit from the at least one CSI report, CSI components pertaining to a CSI part 2 of the at least one CSI report.
  9. The wireless communication method of claim 8, the method further comprising: calculating the sub-configuration priority levels, each sub-configuration priority level being based on a configuration priority value, a respective report configuration identifier, a respective report sub-configuration identifier, a number of configured CSI reports configurations, and/or a respective maximum number of CSI report sub-configurations, or calculating the sub-configuration priority levels, each sub-configuration priority level being based on a CSI report configuration priority value, a respective CSI report configuration identifier, a maximum payload size for a respective CSI report configuration, a maximum payload size for all configured CSI report configurations, and/or a maximum payload size for a part 2 of the at least one CSI report.
  10. The wireless communication method of claim 8 or 9, the method further comprising: receiving, from a network entity, NE, a CSI report sub-configuration indicator identifying one or more of the multiple CSI report sub-configurations to be used to prepare the at least one CSI report, or transmitting, to the NE, the CSI report sub-configuration indicator identifying the one or more of the multiple CSI report sub-configurations used to prepare the at least one CSI report.
  11. The wireless communication method of any of claims 8 to 10, wherein the determining of the subset comprises: selecting the CSI components pertaining to the CSI part 2 based further on at least one of: a predefined components priority order, whether the CSI components are related to a wideband or to a subband, whether the CSI components correspond to one of the multiple CSI report sub-configurations that pertains to a predefined group, whether the CSI components are related to a specific subband-combination, or whether a payload-size of CSI components corresponding to a CSI report sub-configurations among the multiple CSI report sub-configurations not yet included in the at least one CSI report is less than a remaining available payload.
  12. A wireless communication method (500) performed by a network entity, NE, (120) the method comprising: transmitting (534) , to a user equipment, UE, a first control signal conveying at least one channel state information reference signal, CSI-RS, resource and a channel state information, CSI, report configuration including multiple CSI report sub-configurations; transmitting (538) , to the UE, a CSI-RS on the at least one CSI-RS resource; receiving (542) , from the UE, at least one CSI report; and identifying (544) , based on sub-configuration priority levels associated with the multiple CSI report sub-configurations, a subset of the CSI omitted from the at least one CSI report prepared according to the CSI report configuration.
  13. The wireless communication method of claim 12, wherein the sub-configuration priority levels depend on at least one of: report sub-configuration identifiers of the multiple CSI report sub-configurations, number of antenna ports for sub-configuration-related codebooks, or power offsets between the CSI-RS and a physical downlink shared channel.
  14. The wireless communication method of any of claims 12 to 13, the method further comprising: receiving a UE capability control signal specifying a UE capability to omit CSI components from reporting, the UE capability control signal conveying at least one of: a maximum number of configured CSI report sub-configurations per CSI report configuration, a maximum number of configured CSI report sub-configurations across CSI report configurations per component carrier, CC, frequency band, or band combination, a maximum number of reported CSI report sub-configurations per CSI report configuration in a slot, or a maximum number of reported CSI report sub-configurations across CSI report configurations per CC, frequency band, or band combination in the slot.
  15. The wireless communication method of any of claims 12 to 14, wherein the identifying of the subset comprises identifying a non-reported sub-configuration CSI associated with a lower sub-configuration priority level than one or more reported sub-configurations among the multiple CSI report sub-configurations, and the receiving of the at least one CSI report includes receiving individual CSI reports corresponding to the reported sub-configurations.
  16. A wireless communication device (202, 204) comprising a transceiver (256, 236) , a processor (252, 232) , and computer-readable storage media (254, 234) storing executable instructions for the processor to perform any one of methods recited in claims 1-15, using the transceiver.

Description

METHODS AND DEVICES FOR CSI OMISSION WHEN REPORTING MULTIPLE CSI SUB-CONFIGURATIONS FIELD OF THE DISCLOSURE This document generally describes methods and devices operating in wireless communication systems such as (but not limited to) the ones described in 5G standard documents, known as 3GPP communication systems. BACKGROUND In wireless communications, channel state information (CSI) characterizes properties of a radio communication channel. CSI is estimated by comparing a transmitted CSI reference signal (CSI-RS) with a corresponding received signal. For a Multiple-Input Multiple-Output (MIMO) system, the CSI procedure enables a network entity (NE) to select a digital precoder for a user equipment (UE) . In this document, the term NE indicates a base station (BS) , a distributed unit of a distributed BS or another network device of a radio access network (RAN) in communication with the UE. Usually, the NE provides a CSI report configuration to the UE, using radio resource control (RRC) signaling (e.g., CSI-ReportConfig) . In this section, unless specified, a RRC signaling may indicate a RRC reconfiguration message from gNB to UE, or a System Information Block (SIB) , where the SIB can be an existing SIB (e.g., SIB1) or a new SIB (e.g., SIB J, where J is an integer above 21) transmitted by gNB. In some implementations, the network entity may receive the UE capability from a UE or from a core network (e.g., Access and Mobility Management Function, AMF) or another network entity. The CSI-RS is transmitted on a channel measurement resource (CMR) also configured by the NE (e.g., as a CSI-RS resource) . The NE may also configure an interference measurement resource (IMR) enabling the UE to measure channel interference. Based on the configured CMR and IMR, the UE is able to report the CSI, which may include at least one of the following components: a rank indicator (RI) , a precoder matrix indicator (PMI) , a channel quality indicator (CQI) , a layer indicator (LI) , a CSI-RS indicator (CRI) and an SS/PBCH Block Resource Indicator (SSBRI) . The RI  and the PMI characterize the digital precoder, the CQI indicates the signal-to-interference plus noise (SINR) status to assist the NE in determining the modulation and coding scheme (MCS) , and the LI indicates the strongest layer of the precoder indicated by the RI and the PMI. The NE may trigger the UE to provide multiple CSI reports corresponding to multiple CSI report configurations. The CSI report (s) are transmitted using a Physical Uplink Shared Channel (PUSCH) or a long physical uplink control channel (PUCCH) , that is, a PUCCH transmission with more than four symbols. The UE may report the RI and the CQI in CSI part 1, and the PMI, LI, and CQI in the CSI part 2. The payload size for the PMI, LI, and CQI in CSI part 2 is determined based on the reported RI in CSI part 1. The UE transmits the CSI part 1 and CSI part 2 using different resource elements on PUSCH or long PUCCH. The maximum payload size for the CSI part 2 on PUSCH or long PUCCH may also be limited. If the total payload size necessary for the reporting CSI components on CSI part 2 exceeds the maximum payload size, the UE performs a CSI omission procedure. These issues are described in 3GPP technical specifications, for example, 3GPP TS 38.212 section 6.3.2.1.2 and 3GPP TS 38.214 section 5.2.3. The UE then only transmits a portion 110 of the entire CSI to be reported 100 as illustrated in Figure 1. In the illustrated case, the maximum payload size for CSI part 2 allows fully transmitting only the wideband CSI for all CSI reports, the subband CSI for even and for odd subbands according to CSI report 1, and the subband CSI for even subbands according to CSI report 2. The omitted portion 120 includes subband CSI for odd subbands according to CSI report 2 and subband CSI for all other subbands of CSI reports with higher index than 2. The indexing (i.e., report 1, report 2, etc. ) of the CSI reports is based on priority values associated with the CSI reports. The current 3GPP technical specifications provide for determining a CSI report priority value based on a time-domain behavior for the CSI report (e.g., aperiodic, semi-persistent, or periodic) , the serving cell’s index, the report’s content, and/or a CSI report configuration identifier (ID) . The NE may configure multiple (e.g., N with N>1) CSI report sub-configurations in a CSI report configuration but, for saving resources and energy, may  trigger the UE to report CSI corresponding to fewer than all the configured CSI report sub-configurations (e.g., M with 1≤M≤N) . The NE may configure different numbers of antenna ports and/or different power offsets between the CSI-RS and physical downlink shared channel (PDSCH) for different CSI sub-configurations. The NE may perform network port and/or transmission power adaptation based on the received CSI reports. The framework currently defined in the 3GPP technical specifications relative