R1-2600193
discussion
Discussions on 6GR multi-beam operation
From OPPO
Summary
This OPPO contribution proposes 12 specific design changes for 6G multi-beam operation, focusing on minimizing beam sweeping overhead and latency through dedicated measurement RS, AI-based prediction, unified single-beam indication, and a UE-initiated beam management framework. It also includes one observation summarizing AI/ML simulation results from multiple sources.
Position
OPPO proposes replacing NR's general CSI-RS/SRS reuse with dedicated DL and UL beam measurement RS that natively support frequency-domain and time-domain beam sweeping within a single resource. They require separating beam indication from QCL indication (DL) and power control parameters (UL), arguing that lumping them in one TCI state causes configuration inefficiency and unnecessary signaling overhead. OPPO proposes eliminating default beam operation entirely in 6GR, with explicit beam indication required and leaving unspecified cases to UE implementation. They propose studying L1-signaling (DCI) based beam activation and switching for both DL and UL, arguing it offers lower overhead, lower latency, and avoids inter-layer (RAN1/RAN2) collaboration complexity compared to MAC CE. For mobility, OPPO proposes L1 beam switching to trigger multi-TRP transmission scheme switching and cell switching within a 'cell-free' zone, associating beam states directly with TRP/cell configuration. They propose a unified UE-initiated beam management framework that integrates beam failure recovery and event-1 reporting using a common set of candidate beam measurements and a single PUCCH-based uplink transmission mechanism.
Key proposals
- Proposal 1 (Sec Overall): For the multi-beam operation in 6GR: minimize beam sweeping requirement, use AI-based beam prediction to reduce overhead/latency, strive to support single beam operation, and support unified UE-initiated beam management.
- Proposal 2 (Sec DL beam measurement RS): Study dedicated DL beam measurement RS supporting both time-domain and frequency-domain beam sweeping, and both Tx and Rx beam sweeping within one resource.
- Proposal 3 (Sec UL beam measurement RS): Study dedicated UL beam measurement RS supporting time-domain beam sweeping and beam repetition in one resource.
- Proposal 4 (Sec Beam measurement and reporting): Study new beam measurement metric where UE reports RSRP of adjacent Tx beams, and the system calculates the beam direction.
- Proposal 5 (Sec AI-based beam prediction): Study AI/ML-based beam prediction for inter-cell/inter-TRP/multi-TRP scenarios with both NW-side and UE-side model deployment.
- Proposal 6 (Sec DL Beam indication): Reuse unified TCI framework principle; one beam for all DL channels/CSI-RS across all CCs in one band; separate beam indication from other QCL indication; use L1 signaling.
- Proposal 7 (Sec DL Beam indication): Default beam operation is not supported in 6GR; no fixed special system/UE behavior on beam application; if no beam indication, it is up to UE implementation.
- Proposal 8 (Sec DL Beam indication): Study L1-signaling based beam activation, comparing signaling overhead, latency, inter-layer operation necessity, and specification effort against MAC CE based.
- Proposal 9 (Sec UL Beam Indication): Reuse unified TCI framework principle for UL; one beam for all UL channels/SRS across all CCs in one band; separate UL beam indication from power control parameters; use L1 signaling.
- Proposal 10 (Sec Beam Indication for multi-TRP and mobility): Study L1 beam switching based multi-TRP transmission scheme switching, associating multi-TRP transmission scheme configuration with beam(s).
- Proposal 11 (Sec Beam Indication for multi-TRP and mobility): Cell switch between cells within the same 'cell-free' zone based on L1 signaling beam switching; study use cases, feasibility, and determination of applicable cells.
- Proposal 12 (Sec Unified UE-initiated Beam Management Framework): Support a unified UE-initiated beam management framework integrating beam failure recovery and event-1 beam reporting, studying candidate events and a unified uplink transmission mechanism (PUCCH preferred).
- Observation 2.4 (Sec Agreement): Summarizes preliminary simulation results from 13+ sources on AI/ML for beam management including inter-cell/inter-TRP/M-TRP beam prediction, cross-frequency prediction, and MU-MIMO operation.