R1-2508728
discussion
Numerology and frame/slot structure for 6G Radio
From OPPO
Summary
OPPO presents 15 proposals and 4 observations on 6G Radio numerology and frame structure for Rel-21, focusing on a modular baseline design with single subcarrier spacing per frequency range, extended CP removal, and unified 2D time-frequency resource configuration supporting advanced duplex types including dynamic SBFD.
Position
OPPO proposes a modular 6GR air interface design with a Mandatory baseline functionality set supporting both 6G IoT and low-data-rate 6G MBB, where 6G HRLLC reuses the baseline without impacting its design. They require a single SCS per FR/sub-FR per operator's network, opposing multiple numerologies for the same band, and present Option 1 for FR segmentation (extend FR1 to 8.4 GHz with a separate mid-high band 8.4–24.25 GHz using 120kHz SCS). They present technical case against 400MHz single-carrier UE support on RF feasibility grounds (filter performance, PA linearity, flatness), proposing instead 200MHz+200MHz 2-carrier combination transparent to the BS. They propose unified 2D time-frequency resource/transmission direction configuration to replace NR's TDD-centric frame structure, arguing this efficiently supports FD-FDD, semi-static TDD, HD-FDD, gNB semi-static SBFD, and dynamic TDD under one framework, and question the necessity of UE dedicated time-frequency resource configuration if all 6G day-1 UEs are SBFD-aware.
Key proposals
- Proposal 1 (Introduction): Study a set of baseline numerology and a baseline frame structure to fulfil the requirements of 6G eMBB and 6G IoT. The baseline numerology and frame structure are used for 6G HRLLC in Rel-21.
- Proposal 2 (Introduction): Study the additional numerology/frame structure for 6G Sensing and 6G NTN in Sensing/NTN agenda if substantial gain over the baseline numerology/frame structure is justified.
- Proposal 3 (Sec 3.1): For studying 30kHz SCS for FDD in FR1, the assumption is that one operator's 6G network only supports a single SCS for PDSCH/PDCCH or PUSCH/PUCCH after RRC connection per FR/sub-FR.
- Proposal 5 (Sec 3.1): If flexible DL/UL band coupling for a cell is supported, different SCSs for DL and UL are naturally used when the DL and UL bands used for a cell come from different FRs/sub-FRs with different SCSs.
- Proposal 6 (Sec 3.2): No extended CP is supported for 6GR baseline numerology. Longer CP for Sensing or 6G NTN can be studied in Sensing/NTN agenda, without impacting symbol boundary for 6GR TN communication.
- Proposal 7 (Sec 3.3): Extend FR1 to 8.4 GHz and define a separate mid-high band (8.4–24.25 GHz). Consider 120kHz SCS for 8.4–24.25 GHz as baseline. FFS other SCS values.
- Proposal 8 (Sec 3.4): The maximum bandwidth supported by 6GR UE on one carrier is 200MHz, with maximum FFT size of 8K. Study the feasibility and solution of supporting 400MHz CBW at NW side with 2 carriers on UE side.
- Proposal 9 (Sec 4.1): If dynamic SBFD is to be studied, unified design (if can be achieved) for dynamic TDD and dynamic SBFD is preferred.
- Proposal 10 (Sec 4.1): If SBFD operation at UE is to be studied, careful feasibility analysis is necessary with consideration of UE receiver front end saturation and SINR sufficiency for downlink signal decoding.
- Proposal 11 (Sec 4.2): Study 6GR time-frequency configuration (including frame structure) to support: FD-FDD, Semi-static TDD, HD-FDD on UE side, gNB semi-static SBFD, Dynamic TDD. Other duplex types are not precluded if agreed to be studied.
- Proposal 12 (Sec 4.2): For study of unified time-frequency configuration for various duplex types, RAN1 considers 2D time-frequency resource/transmission direction configuration.
- Proposal 13 (Sec 4.2): If all UEs in 6G day 1 are SBFD-aware UEs, RAN1 needs to reconsider the necessity for UE dedicated time-frequency resource configuration.
- Proposal 14 (Sec 5): Reuse the baseline frame/slot structure for 6G Sensing. In case for a symbol to contain a sensing signal, symbol boundary should not be impacted from the communication perspective.
- Proposal 15 (Sec 5): Symbol structure can be studied for sensing without changing symbol boundary. If non-continuous wave is adopted, new symbol structure within the symbol boundary may be considered. If continuous waveform is adopted, new symbol structure within the symbol boundary may be considered.