R1-2601790
discussion
Discussion on beam management for downlink and uplink for 6GR air interface
From FUTUREWEI
FUTUREWEI's prior position on
10.5.2.4
at
RAN1#124
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Proposes adopting the 5G NR MIMO/RS/CSI framework as the starting point for 6G, arguing no fundamental paradigm shift is needed while supporting substantial evolution for upper midband around 7 GHz and 15 GHz. Presents a mixed antenna architecture combining low-resolution 1-bit all-digital receiver arrays for one-shot beam acquisition with analog/hybrid arrays for data transmission, supported by feasibility results showing near-ideal beamforming gain. Requires QCL/TCI enhancements to enable UL signals (SRS) as QCL source RS for DL TCI states, extending the Rel-17/18 unified TCI framework. Proposes AI/ML as an integral part of the 6G MIMO framework from day-1, identifying cross-frequency beam prediction (FR1-to-FR2) as a candidate use case requiring study of data collection configuration, inference-related resource configuration, and LCM operations including fallback and model switching.
Summary
Futurewei presents 3 Observations and 7 Proposals on 6G beam management, covering one-shot beam acquisition, QCL/TCI enhancements using UL signals, UE-initiated beam management latency reduction, AI/ML cross-frequency beam prediction, and simulation assumptions.
Position
Futurewei proposes a mixed antenna architecture combining a low-resolution all-digital receiver array for one-shot beam acquisition with an analog/hybrid array for data transmission to eliminate beam sweeping procedures. They require enabling UL signals (e.g., SRS) as QCL source RS for DL TCI states, departing from 5G NR's restriction to only DL signals. For UEIBM, they propose a network confirmation mechanism that updates TCI states and activates new beams without RRC reconfiguration or MAC-CE signaling, targeting approximately 30 ms latency reduction. On AI/ML, they support cross-frequency beam prediction using angular-delay domain FR1 channel inputs to predict mmWave beams, demonstrating feasibility for co-located scenarios with Transformer-based architectures. They propose specific LLS/SLS simulation parameters prioritizing around 7 GHz and 30 GHz with beam acquisition latency and overhead as primary performance metrics.
Key proposals
- Proposal 1 (Sec 2.1.1): For 6GR beam management, support one-shot beam acquisition for fast beam acquisition.
- Proposal 2 (Sec 2.1.2): In 6GR, support QCL/TCI enhancements to enable the use of UL signal (e.g., SRS) as QCL source RS of DL TCI states.
- Proposal 3 (Sec 2.2): In 6GR, consider the unified TCI framework developed in 5G NR as a starting point for 6GR QCL/TCI framework.
- Proposal 4 (Sec 2.3): Support the three events (e.g., Event-1, Event-2, and Event-7) defined in 5G NR UEIBM as a starting point for event definition in UEIBM for 6GR.
- Proposal 5 (Sec 2.3): In UEIBM for 6GR, support enhancements to facilitate UEIBM beam switching with network confirmation for latency reduction.
- Proposal 6 (Sec 2.4.3): Consider AI/ML-based cross-frequency beam management, e.g., predicting the optimal mmWave beam(s) using sub-6GHz channel information, as a candidate approach for Beam Management enhancement in 6GR study.
- Proposal 7 (Sec 2.5): Adopt assumptions in Table 2 and Table 3 as the LLS and SLS EVM assumptions, respectively, for evaluation of 6GR beam management.