R1-2601793
discussion
Other Aspects for CSI acquisition
From FUTUREWEI
FUTUREWEI's prior position on
10.5.3.3
at
RAN1#124
· AI-synthesized, paraphrased
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Proposes adopting the 5G NR MIMO/RS/CSI framework as a complete baseline for 6G without fundamental paradigm shifts. Proposes studying multi-port TRS as a QCL source where a UE applies a signaled or estimated precoding vector to received multi-port TRS to form an effective single-port TRS that matches the precoding of target DMRS/CSI-RS, reducing channel estimation degradation from precoding mismatch. Proposes supporting early/on-demand tracking acquisition via aperiodic TRS (and optionally aperiodic SSB) as a mandatory feature for fast SCell/SCC activation and an optional feature for early CSI acquisition before CONNECTED. Proposes integrating AI/ML into the MIMO framework from day-1 of 6G with discussion of high-level principles and identification of a few use cases. Additionally proposes studying UMB support including advanced Tx/Rx technologies, overhead reduction for CSI-RS/DMRS, and hybrid antenna architecture, and studying fast beam acquisition via augmented antenna architecture for one-shot beam acquisition.
Summary
This document from Futurewei contains 2 main proposals addressing enhancements for CSI acquisition in 6G. It focuses on introducing multi-port TRS to improve QCL parameter derivation for massive MIMO and supporting early/on-demand tracking acquisition for fast SCell activation and CSI acquisition before CONNECTED mode.
Position
Futurewei proposes studying multi-port TRS as a QCL source to address precoding mismatch between single-port TRS and dynamically precoded DMRS/CSI-RS in massive MIMO systems, suggesting the UE applies a precoding vector to the multi-port TRS to form an effective 1-port TRS matching the target signal's precoding. They argue that the precoding discrepancy grows with array size, leading to channel estimation performance degradation, SINR loss, and lower throughput in upper midband deployments. The company also requires early/on-demand tracking acquisition to be a mandatory feature for fast SCell/SCC activation, with aperiodic TRS transmission following the activation command, while framing early CSI acquisition before CONNECTED as an optional advanced feature for capable UEs.
Key proposals
- Proposal 1 (Sec 2.1/3): Study to introduce multi-port TRS as a QCL source for DL transmissions using massive MIMO antenna arrays, to reduce the mismatch of the precoding of TRS and that of DMRS/CSI-RS, improving the channel estimation performance.
- Proposal 2 (Sec 2.2/3): Support early/on-demand tracking acquisition in 6G as a mandatory feature for fast SCell/Secondary Component Carrier (SCC) activation and as an optional feature for early CSI acquisition before CONNECTED.