R1-2601902
discussion
Design of WUS with OFDM based sequence
From Ericsson
Summary
This Ericsson Tdoc for 6G discusses the design of a Downlink Wake-up Signal (WUS) using OFDM-based sequences, covering general principles, multiplexing, synchronization, coverage, sequence design, and evaluation methodology. It presents 16 specific proposals and 13 observations, emphasizing UE power saving benefits and proposing key performance targets for missed detection and false alarm rates.
Position
Ericsson proposes that the 6G DL WUS based on OFDM sequences be designed for all RRC states with commonality to reduce complexity. They require OFDM sequences to be defined in the frequency domain, arguing this provides lower base station complexity and more efficient multiplexing compared to time-domain definition. For performance, they propose a missed detection rate of less than 10^-2 and a false alarm rate target around {10^-1, 10^-2} as starting points, while requiring that overall paging/PDCCH misdetection performance not be significantly impacted. They support a configurable WUS duration to address different coverage conditions for 1-Rx/2-Rx UEs and extended coverage scenarios, and propose studying various sequence types like ZC, M, and Gold sequences, with a preference for reusing sequences planned for 6G synchronization/reference signals. Ericsson presents initial results showing 60-80% UE energy saving in Idle mode and provides specific link-level results mapping required SNR to WUS duration for different Rx antenna configurations.
Key proposals
- Proposal 1 (Sec 2): The 6GR WUS should be considered for all RRC states (e.g., Idle/Inactive, Connected) and it should provide energy saving for the UE in different use cases and scenarios including eMBB and non-eMBB (e.g., IoT, etc.).
- Proposal 3 (Sec 2.1): It should be possible to efficiently multiplex DL WUS with other 6GR transmissions (and other DL WUS) in time or frequency domain without causing interference.
- Proposal 5 (Sec 2.2): For synchronization and measurements, the UE in the energy efficient (EE) processing state should be able to re-use 6GR sync signal (e.g., 6GR SSB) without any need for additional sync signal.
- Proposal 6 (Sec 3.1): The design of DL WUS should ensure support at least for 1-Rx, 2-Rx UEs, and 'extended coverage' scenarios for all types of UEs.
- Proposal 8 (Sec 3.1): The overall paging and DCI misdetection performance of the UE should not be significantly impacted when WUS is used by the UE for power saving.
- Proposal 9 (Sec 3.1): A missed detection rate of less than 10-2 (e.g., ~0.5%) and false alarm rate of around {10-1, 10-2} should be considered as starting points for the design of WUS.
- Proposal 10 (Sec 3.2): The OFDM sequences should be defined in the frequency domain.
- Proposal 11 (Sec 3.2): Study the performance of various WUS OFDM sequences such as ZC, M, and Gold sequences and consider sequences that are expected to be introduced for 6GR DL synchronization/reference signals.
- Proposal 12 (Sec 3.3): The WUS payload should be small-medium (e.g., ≤ [8] bits) depending on the WUS functionalities.
- Proposal 13 (Sec 3.4): Consider per-group paging rate range 0.01%-10% per PO.
- Proposal 14 (Sec 3.4): The WUS evaluations should include UE energy saving, coverage, false alarm and missed-detection performance, system overhead and network energy consumption, measurements and synchronization performance.
- Proposal 15 (Sec 3.4): For link-level and link-budget evaluations, the evaluation assumptions in AI 10.1 should be used as the baseline and, if needed, specific assumptions can be considered for WUS evaluations.
- Proposal 16 (Sec 3.4): Study the design of WUS considering bandwidth and duration, type of OFDM sequence, and signal structure under different assumptions on time-frequency errors and payload.