R1-2601889
discussion
Maintenance of Rel-19 AI/ML for air interface
From Huawei
Summary
This Huawei contribution addresses remaining issues for Rel-19 AI/ML-based beam management, specifically focusing on resource handling for virtual CSI-RS and PUCCH reporting constraints. The document presents four text proposals to relax legacy rate-matching rules for non-transmitted resources in Set A/B, support zero-padding for small RS-PAI payloads on PUCCH, and align RRC parameter notations across TS 38.214 and TS 38.212.
Position
Huawei proposes relaxing legacy PDSCH rate-matching rules in TS 38.211 to exclude NZP CSI-RS resources that are only configured in Set A (for inference or applicability check) or Set B (for applicability check Option B), arguing these virtual resources are not actually transmitted and thus should not waste PDSCH resources. They prefer zero-padding for 1-bit or 2-bit RS-PAI payloads on PUCCH over restricting the number of transmission occasions (M), citing simplicity and alignment with existing CSI part 2 padding mechanisms. Huawei requires aligning RRC parameter notations in TS 38.214 and TS 38.212 with TS 38.331, specifically standardizing terms like 'resourcesForChannelPrediction-r19' and 'csi-PAI-r19'. They argue that for Option B applicability checks, resources configured for prediction and measurement are only for applicability verification and do not trigger actual measurement or rate-matching behaviors.
Key proposals
- Proposal 1 (Sec: Text proposal for relaxation of legacy rate matching rule): Consider the text proposal in Table 1 to clarify that PDSCH rate-matching is not performed around NZP CSI-RS resources that are only configured in Set A (for inference or applicability check) or Set B (for applicability check Option B), as these are virtual resources not actually transmitted.
- Proposal 2 (Sec: Issue of 1-bit or 2-bit RS-PAI on PUCCH): Consider the text proposal in Table 2 to support 1-bit or 2-bit RS-PAI reporting on PUCCH by applying zero-padding to the UCI bit sequence until its length equals 3 bits, avoiding restrictive configuration limits on the number of transmission occasions.
- Proposal 3 (Sec: RRC parameter notation alignment for TS 38.214 and TS 38.212): Adopt the text proposal for TS 38.214 in Table 3 to align RRC parameter notations with TS 38.331, specifically correcting terms like 'csi-pai-r19' to 'csi-PAI-r19' and 'resourcesForSetA-r19' to 'resourcesForChannelPrediction-r19'.
- Proposal 4 (Sec: RRC parameter notation alignment for TS 38.214 and TS 38.212): Adopt the text proposal for TS 38.212 in Table 4 to align RRC parameter notations with TS 38.331, ensuring consistency in parameter naming conventions across physical layer and MAC/RLC specifications.
- Observation (Sec: Resources of Set A in inference CSI report): Huawei argues that legacy rate-matching rules for standalone NZP-CSI-RS not configured in any CSI-ResourceConfig should be borrowed for Rel-19 BM, meaning UEs do not need to perform rate-matching around NZP-CSI-RS configured only for Set A if it is not actually transmitted.
- Observation (Sec: Resources of Set A/Set B in Step 3 under applicability report Option B): Huawei states that for Option B applicability checks, resources configured in resourcesForChannelPrediction-r19 and resourcesForChannelMeasurement-r19 are only for applicability checks and not really transmitted, so rate-matching around these resources is not performed.
- Technical Argument (Sec: Issue of 1-bit or 2-bit RS-PAI on PUCCH): Huawei opposes restricting the value of M (number of transmission occasions) for RS-PAI, arguing that zero-padding is a simpler and unified solution compared to configuration restrictions, leveraging existing zero-padding support for CSI part 2.
- Technical Argument (Sec: Resources of Set A in inference CSI report): Huawei suggests a simple gNB implementation method where K fixed CSI-RS IDs are configured for P2 sweeping, and the QCLed CSI-RS ID is dynamically indicated to these K IDs, addressing concerns about predicted CSI-RSs needing actual transmission.
- Proposal 1 Detail (Sec: Text proposal for relaxation of legacy rate matching rule): The proposal modifies TS 38.211 Clause 7.3.1.5 to explicitly exclude non-zero-power CSI-RS configured only by resourcesForChannelPrediction-r19 in CSI-ReportConfig or ApplicabilitySetConfigCSI-r19 from PDSCH rate-matching criteria.
- Proposal 2 Detail (Sec: Issue of 1-bit or 2-bit RS-PAI on PUCCH): The proposal modifies TS 38.212 Clause 6.3.1.1.2 to append zeros to the UCI bit sequence if its length is less than 3 bits, specifically addressing the case where RS-PAI payload size is 1 or 2 bits.
- Proposal 3 Detail (Sec: RRC parameter notation alignment): The proposal updates TS 38.214 to use consistent naming such as 'p-CRI-r19', 'p-CRI-RSRP-r19', 'p-SSB-Index-r19', 'p-SSB-Index-RSRP-r19', 'rs-PAI-r19', 'csi-PAI-r19', 'noneBM-r19', and 'noneCSI-r19' to match TS 38.331.
- Proposal 4 Detail (Sec: RRC parameter notation alignment): The proposal updates TS 38.212 to use consistent naming such as 'p-CRI-r19', 'p-CRI-RSRP-r19', 'p-SSB-Index-r19', 'p-SSB-Index-RSRP-r19', 'rs-PAI-r19', 'csi-PAI-r19', 'noneBM-r19', and 'noneCSI-r19' to match TS 38.331.
- Observation (Sec: UE assumption on virtual resources for UE-side model): Huawei notes that the time domain behavior of an NZP-CSI-RS is configured in CSI-ResourceConfig, meaning if an NZP-CSI-RS is not configured within any CSI-ResourceConfig, its time domain behavior is absent and it is not actually transmitted.
- Observation (Sec: Resources of Set A/Set B in Step 3 under applicability report Option B): Huawei highlights that ApplicabilityReportConfig for Option B reuses IEs for resource configurations (resourcesForChannelPrediction-r19 and resourcesForChannelMeasurement-r19) which refer to individual CSI-ResourceConfigId, but these are not for actual measurement.
- Proposal 1 Consequence (Sec: Text proposal for relaxation of legacy rate matching rule): If not approved, the resource occupied by the virtual CSI-RS in Set A or Set B cannot be used for PDSCH transmission, leading to unnecessary waste of resources.