R1-2601879
discussion
Beam management for downlink and uplink
From Kyocera Corporation
Kyocera Corporation's prior position on
10.5.2.4
at
RAN1#124
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Proposes reusing the Rel-18/19 inter-cell AI/ML beam management framework for Distributed MIMO (D-MIMO) scenarios with multi-TRP transmission, using 5G NR 2-TRP operation as a baseline reference and studying m-TRP operation with more than 2 TRPs while documenting throughput gains versus complexity. Proposes studying spatial domain beam prediction to reduce the number of searches and processing time across multiple TRP beam candidates, specifically reusing the Set A / Set B mechanism from Rel-18/19 for efficient TRP selection based on UE measurement reports. Proposes extending temporal-domain beam prediction to D-MIMO to improve beam tracking and enable seamless TRP switching for mobile UEs. Proposes studying beam management for multiple TRP deployments considering multiple UEs connecting to multiple TRPs simultaneously, and specifically studying efficiency improvements for CSI-RS reporting in D-MIMO, noting that current L1-RSRP reporting limits of N = 6 or 8 may provide insufficient prediction accuracy for joint transmission scheduling.
Summary
Kyocera's R1-2601879 contribution for 6GR beam management presents 11 proposals and 8 observations covering simulation assumptions, QCL/beam indication, beam measurement/report, and UE-initiated beam management (UEIBM), advocating for a unified TCI/QCL framework baseline, simplified QCL chains, enhanced mTRP and inter-cell signaling, and a refined event-driven UEIBM procedure with conditional network response.
Position
Kyocera proposes adopting the Rel-17/18 unified TCI framework and existing QCL rules as the baseline for 6GR beam indication without redesign. They propose studying a streamlined QCL property/chain design that evaluates removing or reducing reliance on UE-specific periodic TRS as a QCL source RS, explicitly assessing impacts on tracking/channel estimation robustness, system performance, and overhead/energy consumption. They propose studying low-latency beam indication mechanisms including prediction-assisted methods realizable with AI/ML and non-AI approaches to reduce beam update latency in high-mobility and dense mTRP deployments. For AI/ML beam management, they propose studying methods to address associated ID limitations including potential disclosure of NW proprietary information across sTRP and mTRP scenarios. For UEIBM, they propose eliminating Events 1, 2, 3, and 9 as redundant, and modifying Event-5 to support mTRP dynamic switching between DPS and CJT modes where the UE reports a group of M TRPs meeting quality conditions. They propose studying and specifying an event-driven UEIBM UL reporting framework with aperiodic UL procedure and conditional network response only when beneficial.
Key proposals
- Proposal 1 (Sec 2): Proposes detailed link-level simulation assumptions for 6GR beam management evaluation, including carrier frequencies around 4/7/30 GHz, specific channel models (CDL-A/B/C), BS/UE antenna configurations, and beam sweeping procedures.
- Proposal 3 (Sec 3): Supports Rel-17/18 unified TCI framework and existing QCL rules as the baseline starting point for 6GR beam indication for DL/UL, across sTRP/mTRP and intra/inter-cell/carrier scenarios, to avoid re-design and reduce implementation complexity.
- Proposal 4 (Sec 3): Studies a unified beam indication/signaling design that supports both intra-cell and inter-cell beam switching under consistent TCI/QCL semantics.
- Proposal 5 (Sec 3): Studies enhancements to the unified TCI indication framework to support mTRP beam indication, including the design space of a unified TCI framework that involves joint and separate DL/UL TCI state(s) for mTRP while considering sTRP as a special case.
- Proposal 6 (Sec 3): Studies mechanisms within the QCL/TCI framework to alleviate frequent TCI switching (including cases where QCL source RS beamwidth differs from the target signal beamwidth).
- Proposal 7 (Sec 3): Studies a streamlined QCL property/chain design for 6GR beam indication that evaluates reducing/removing reliance on UE-specific periodic TRS as a QCL source RS and investigates low-latency beam indication mechanisms including prediction-assisted methods via AI/ML and non-AI approaches.
- Proposal 8 (Sec 4.1): Considers topics for mTRP operation including improvements to group-based reporting (hardware constraints, inter-TRP interference, RS overhead) and prioritizing CJT study with attention to hardware reciprocity mismatch, limited resources, channel aging, and feedback quantization limitations.
- Proposal 9 (Sec 4.2): Studies methods to address the limitations of the associated ID approach, such as the potential disclosure of NW proprietary information, encompassing both sTRP and mTRP scenarios.
- Proposal 10 (Sec 5.1): For UEIBM, considers a refined set of events as a starting point (Event-4, Event-5 modified for mTRP DPS/CJT dynamic switching, Event-6, Event-7a, Event-7b, Event-8), omitting Events 1, 3, and 9 as redundant and repurposing Event-5 for mTRP coordination.
- Proposal 11 (Sec 5.2.1): Studies and specifies an event-driven UEIBM UL reporting and response framework with aperiodic/bursty UL procedure conveying event-driven indication and current-vs-candidate beam information, enabling conditional network response only when beneficial.