R1-2601820
discussion
Discussion on design of WUS with OFDM based sequence
From Spreadtrum
Spreadtrum's prior position on
10.6.1.1
at
RAN1#124
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Proposes using 5G Rel-19 LP-WUS functionality (subgroup paging indication, PDCCH monitoring indication, serving cell measurement) as the baseline for 6G DL WUS with OFDM-based sequence. Requires a single unified WUS solution for all device types and requires cell-wise coverage to achieve complete UE power saving gain, with Msg3 coverage as the starting point. Proposes studying CP-OFDM as the waveform, arguing no distinct power consumption difference versus DFT-S-OFDM when considering FFT-based correlation and noting CP-OFDM simplifies operation when WUS is FDMed with other CP-OFDM signals. Proposes studying both 6G SSB reuse and dedicated LP-SS for synchronization, and proposes evaluating Gold, M, and ZC sequences with a payload of at least 5 bits. Argues that WUS reliability targets for miss detection and false alarm rates require dedicated study due to potential low-precision hardware and synchronization errors in EE processing state.
Summary
Spreadtrum's contribution to RAN1#124bis provides 9 proposals on 6G DL WUS design, emphasizing a unified OFDM-based sequence approach for all device types and RRC states. The document covers evaluation assumptions, waveform selection, synchronization, and information content across multiple design dimensions.
Position
Spreadtrum proposes a unified DL WUS design for all device types to avoid market fragmentation. They prefer CP-OFDM waveform over DFT-S-OFDM based on Rel-18 power consumption evaluations showing marginal UE-side difference and cite loss of PAPR advantage when frequency-division multiplexed with other CP-OFDM signals at the gNB. They propose reusing TR 38.869 evaluation assumptions with revisions reflecting EE processing state agreements and 6GR frequencies including 7GHz. They require at least 5-bit payload for DL WUS information and support a single information provisioning method (codepoint mechanism) across idle and connected modes. On network impact, they argue latency is not tightly related to DL-WUS design itself but rather to ramp-up time and SSB processing time, and propose revising FL's proposal to replace NES with network energy consumption.
Key proposals
- Proposal 1 (Design for different devices): Strive one unified design of DL WUS for different device types.
- Proposal 2 (Coverage - Evaluation assumptions): For evaluation of coverage for 6GR DL WUS, evaluation assumptions in Table 1 can be considered.
- Proposal 3 (Coverage - Metrics): MDR and FAR in TR 38.869 can be considered as starting point, e.g., 1% MDR and 1% FAR.
- Proposal 4 (Waveform): Study and evaluate DL WUS with OFDM based sequence with CP-OFDM waveform.
- Proposal 5 (Synchronization): At least the 6GR sync signals are used for providing UE sync prior to receiving DL WUS.
- Proposal 6 (RRM measurement): Study RRM measurement in agenda 10.6.1.2.
- Proposal 7 (NW impact): Study impact of DL WUS at least with respect to System overhead, BS implementation complexity, Network energy consumption, Spectrum efficiency, FFS: Latency.
- Proposal 8 (Information content - Payload): The information carried by DL WUS is at least 5 bits.
- Proposal 9 (Information content - Provisioning): A single information provisioning way for different RRC states should be considered in 6GR DL WUS design.