R1-2509348
discussion
Overview of 6G Air Interface
From CEWiT
Summary
This CEWiT contribution provides a broad overview of 6G air interface design across 13 proposals and 10 observations, covering scalable device design, common signal/channel design, Multi-RAT Spectrum Sharing (MRSS), coverage, positioning, sensing, spectrum aggregation, BWP adaptation, and NTN.
Position
CEWiT proposes determining a minimum set of common features applicable to all 6G device types with a 2-step design approach for common procedures (step 1: simple/energy-efficient for all device types; step 2: capability/device-type specific). They recommend designing common signals/channels for the smallest Maximum UE BW and minimum spectrum allocation (Option 1) or considering >3 MHz as minimum (Option 2) with additional scaling procedures for 3 MHz cases, arguing Option 3 (separate designs per band) increases complexity. CEWiT proposes studying MRSS with minimum NR signal sharing restricted to at least Sync signal (SSB) sharing, citing overhead reduction (~9% SSB overhead maintained vs. 18% with separate transmissions) and energy efficiency gains for base stations and Multi-SIM UEs. They propose introducing new lower numerology 7.5 kHz at least for sub-1GHz bands for coverage enhancement while matching 5G timing boundaries, require standalone positioning and sensing as day-1 services with the NR positioning framework as baseline, propose studying a unified multi-carrier aggregation framework with DL/UL decoupling and on-demand SSB, and propose studying enhanced BWP adaptation via L1-triggered adaptation with cell/group-wise indication for network energy saving.
Key proposals
- Proposal 1 (Sec Introduction): Determining minimum set of common features, which are applicable to all 6G device types supported
- Proposal 4 (Sec Smallest Maximum UE BW and Minimum Spectrum allocation): Following options can be considered for designing common signals/channels: Option 1: Single common signals/channels design for smallest Maximum UE BW and minimum spectrum allocation. Option 2: Single common signals/channels design considering smallest Maximum UE BW and minimum spectrum allocation as >3 MHz; Specify additional procedures for specific cases (E.g., scaling for 3 MHz spectrum allocation/ UE capable of 3 MHz band)
- Proposal 5 (Sec MRSS): 6G MRSS should support minimum NR signal sharing with 6GR. This can be restricted to at least Sync signal sharing.
- Proposal 8 (Sec Coverage): 6G should consider coverage related requirements from first release; FR3 coverage w.r.t FR1 should be addressed especially for 6G-CA; New lower numerology(ies) should be introduced in the 6GR at least for sub-1GHz bands to achieve better coverage, still matching the timing boundaries of 5G. The lower numerology 7.5kHz should be considered as a candidate; 6G modulation and waveform should consider coverage as one critical aspect in defining requirements, while adapting the coverage schemes from 5G.
- Proposal 9 (Sec Positioning): 6G should support standalone positioning service from day1 and also investigate RAN based positioning feature.
- Proposal 10 (Sec Sensing): Sensing should be considered as a day 1 service for 6G. Consider studying all use cases in TR 22.837, involving both gNB and UE; Sensing framework of 6G should be designed transparent to the communication framework; Sensing waveform, co-existence with communication channels and signals and Sensing performance should be studied.
- Proposal 11 (Sec BW operations and resource aggregation): RAN1 can study enhancements to the NR spectrum utilization and aggregation framework to improve flexibility, efficiency, and scalability for 6G systems, including Unified Multi-Carrier Operation, Non-Co-located spectrum aggregation, DL/UL decoupling, carrier ON/OFF, on-demand SSB, fast carrier addition/activation, PCell-SCell swap, improved cross-carrier scheduling, and support for both IDLE/INACTIVE and CONNECTED states.
- Proposal 12 (Sec Enhanced UE BWP adaptation): Study and evaluate enhanced NR BW adaptation mechanism for 6G EE improvement, regarding adaptation of bandwidth-dependent parameters, faster adaptation without BWP switching delay by restricting parameter set, L1-triggered adaptation with improved reliability, and cell/group-wise indication for network energy saving.
- Proposal 13 (Sec NTN): In 6GR, further aspects to consider for supporting NTN include HARQ, spectrum utilization and aggregation framework, timing and frequency synchronization adjustment, and network verified UE location.
- Proposal 6 (Sec MRSS): The following high-level aspects are proposed for consideration in the study and design of MRSS between NR and 6GR: Resource allocation coordination (can be restricted to only initial access), Radio resource utilization, UE and network implementation complexity, Signalling overhead, Operating bands and carrier configurations, NR and 6GR TRP co-location, Network energy efficiency, Numerology impact and alignment, Frame, slot, and symbol boundary alignment.