R1-2600061
discussion
Discussion on 6G WUS Operation in RRC States
From FUTUREWEI
Summary
Futurewei's Tdoc R1-2600061 provides 10 observations and 2 proposals on 6G DL WUS of OFDM based sequence, comparing Rel-19 LP-WUS and Rel-16/17 PEI/DCP designs across RRC states. The document proposes a unified design for both RRC IDLE/INACTIVE paging indication and RRC CONNECTED energy saving, leveraging improved coverage and codepoint-based signaling.
Position
Futurewei proposes a unified 6G DL WUS of OFDM based sequence design that claims functionality from both Rel-17 PEI and Rel-19 LP-WUS for RRC IDLE/INACTIVE operation, using codepoint-based indication with at least an all subgroups codepoint and supporting a maximum of at least 31 subgroups per PO with association to at least 4 POs. They argue that 6G UE 'EE processing' power state assumptions—specifically no NF degradation relative to the main radio and relative power within Rel-18/19 LP-WUR ON range—enable PDCCH as the coverage target, extending energy saving to full cell coverage. This eliminates the need for Rel-19's conditional entry/exit condition based on serving cell measurements. For RRC CONNECTED operation, they propose starting from Rel-19 Option 1-2 monitoring to decouple measurement requirements from PDCCH monitoring and support energy saving during short DRX cycles, while requiring SCell dormancy indication capability and increased wake-up capacity beyond Rel-19 LP-WUS to fully claim Rel-16 DCP functionality.
Key proposals
- Observation 1 (Sec 3.1): Rel-19 LP-WUS coverage was mainly driven by lowest LP-WUR capability, i.e., OOK signal detection performance and NF of up to 8dB above MR’s, and therefore limited cellular coverage with PUSCH msg3 as target was considered.
- Observation 2 (Sec 3.1): 6G UE power model defines “EE processing” as an energy efficient state that captures the processing of DL WUS (or other 6G signal) of OFDM based sequence without degradation in UE’s NF and with relative power within the range of Rel-18/19 LP-WUR ON state.
- Observation 3 (Sec 3.1): Compared to Rel-19 LP-WUS, DL WUS of OFDM sequence can have PDCCH as the coverage target extending UE energy saving to the full cell coverage at similar or lower resource overhead.
- Observation 4 (Sec 3.2): While Rel-17 PEI supports wake-up indication of upto 8 subgroups per PO for upto 2 consecutive PFs, Rel-19 LP-WUS supports upto 31 subgroups per PO for upto 4 POs. A UE monitoring either PEI or LP-WUS is not required to monitor associated PO if neither is detected or its corresponding subgroup is not indicated.
- Observation 5 (Sec 3.2): Compared to PEI bitmap wake-up indication, LP-WUS supports codepoint indication with an all subgroup per PO wake-up indication codepoint, which is sufficient for energy saving given the low probability of more than one subgroup indication in any paging cycle.
- Observation 6 (Sec 3.2): Compared to PEI cell level activation/deactivation, LP-WUS uses additional entry/exit condition due to coverage constraint which is not needed for 6GR DL WUS of OFDM based sequence with PDCCH as the coverage target.
- Proposal 1 (Sec 3.2): Consider DL WUS of OFDM based sequence for a unified early paging indication functionality in 6G using codepoints with at least an all subgroups indication codepoint, while supporting a maximum of at least 31 subgroups per PO and association to a maximum of at least 4 POs.
- Observation 7 (Sec 3.3): Rel-16 DCP supports SCell dormancy indication and can support wake-up indication of up to 140 UEs using bitmap indication if the SCell dormancy indication is not configured.
- Observation 8 (Sec 3.3): Rel-19 LP-WUS does not support SCell dormancy indication and only uses codepoint for wake-up indication of one of upto 32 UEs without grouping in RRC Connected state.
- Observation 9 (Sec 3.3): Both Rel-16 DCP and Rel-19 LP-WUS are supported and are only configured on the PCell and/or PSCell when a UE is configured with CA. They can also be configured along with PDCCH skipping and SSSG switching.
- Observation 10 (Sec 3.3): Compared to Rel-16 DCP, Option 1-2 of Rel-19 LP-WUS monitoring in RRC Connected state (i.e., UE starts PDCCH monitoring timer after LP-WUS reception) allows LP-WUS monitoring even when short DRX cycle is configured and decouples measurement requirements from PDCCH monitoring.
- Proposal 2 (Sec 3.3): Consider how to support dormancy indication using DL WUS of OFDM based sequence with an increased wake-up indication capacity, compared to Rel-19 LP-WUS design, for a unified energy saving information notification functionality in RRC Connected state of 6G.