R1-2601784
discussion
Discussion on 6G Design of WUS with OFDM based Sequence
From FUTUREWEI
FUTUREWEI's prior position on
10.6.1.1
at
RAN1#124
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Proposes adopting a DL WUS based on an OFDM sequence with at least PDCCH as a coverage target, replacing Rel-16 DCP and Rel-17 PEI functionality for a unified 6G energy saving solution. Proposes using Rel-19 LP-WUS design as a starting point, maintaining the pre-DFT OFDM sequence overlay definition to enable time-domain EE processing at the UE, but explicitly requires the removal of the underlying OOK signal and Manchester encoding constraint. Proposes a new design for the length and number of candidate OFDM sequences per OFDM symbol, redesigned for the PDCCH coverage target and UE processing complexity without the OOK signal. Proposes direct mapping of raw information bits to OFDM sequences with a configurable number of repetitions for simplified EE UE processing.
Summary
This Futurewei contribution discusses the design of 6G downlink Wake-Up Signal (WUS) using OFDM-based sequences, building on Rel-19 LP-WUS. It presents 6 observations and 5 proposals, arguing for extending coverage to the PDCCH target and proposing design simplifications by removing the underlying OOK signal.
Position
Futurewei proposes reusing Rel-19 LP-WUS design aspects, specifically Zadoff-Chu OFDM sequences defined before DFT processing, as a starting point for 6G DL WUS but requires removing the underlying OOK signal and Manchester encoding. They propose targeting Broadcast PDCCH coverage with an MDR of 1% and FAR of {0.1%,1%}, citing an expected ~1.13dB coverage gap with 5G NR Broadcast PDCCH based on NF improvement and OFDM detection gains over OOK. They propose that the DL WUS of OFDM-based sequence can replace Rel-16 DCP and Rel-17 PEI functionalities for a unified energy-saving solution. They call for a new design of candidate OFDM sequence length and number per symbol to achieve the PDCCH coverage target without depending on OOK-based power boosting. They propose direct mapping of raw information bits to OFDM sequences with configurable repetitions for simplified, energy-efficient UE processing.
Key proposals
- Proposal 1 (Sec 3.1): Reuse 5G NR LP-WUS MDR of 1% and FAR of {0.1%,1%} as design targets and consider Broadcast PDCCH as the coverage target for 6G DL WUS design.
- Proposal 2 (Sec 3.1): Consider the adoption of DL WUS of OFDM based sequence with DCP/PEI functionality replacement for a unified energy saving solution in 6G.
- Proposal 3 (Sec 3.2): Consider Rel-19 LP-WUS design with Zadoff-Chu OFDM sequences overlaid OOK ON chips before DFT processing for 6GR DL WUS of OFDM based sequence with the removal of the underlying OOK signal with Manchester encoding constraint.
- Proposal 4 (Sec 3.2): Consider a new design of the length and number of candidate OFDM sequences per OFDM symbol for 6GR DL WUS of OFDM based sequence without underlying OOK signal and Manchester encoding considering PDCCH coverage target and UE’s processing complexity.
- Proposal 5 (Sec 3.2): Similar to Rel-19 LP-WUS, raw information bits can be mapped directly to OFDM sequences for 6GR DL WUS and a configured number of repeitions may be considered for performance/coverage improvement, if needed, for a simplified and EE UE processing.