R1-2509350
discussion
Views on 6GR frame structure
From CEWiT
Summary
This document from CEWiT presents 11 proposals and 4 observations for the 6G Radio (6GR) frame structure study, covering NTN requirements, new numerologies, FFT sizes, and TDD configurations.
Position
CEWiT proposes a unified timing advance framework for 6GR covering both TN and NTN, requiring UE specific TA adjustment calculated from fix offset, configured common TA, 6gNB estimated value, and UE estimated value using GNSS. They require GNSS resilient operation to be considered from day1 in 6G initial access design, using Rel-20 NR-NTN GNSS resilience study outcomes as baseline. CEWiT proposes introducing lower numerology of 7.5kHz SCS for sub-1GHz bands to improve UL coverage for LPWAN and eMBB, and proposes maximum FFT sizes of 8192 and 16384. They deprioritize dynamic TDD and DCI-based slot format indication in 6G day 1, instead supporting semi-static cell and UE/group specific TDD configurations with SBFD symbols indicated alongside DL and UL symbols without redundancy, and requiring TDD configurations to provide UE link direction in SBFD symbols to avoid dynamic switching between DL and UL subbands.
Key proposals
- Proposal 1 (Sec NTN requirements): For 6G initial access design, GNSS resilient operation should be considered from day1, while designing the timing advance framework of 6GR, starting from initial access.
- Proposal 2 (Sec NTN requirements): In 6G RAN, the uplink frame timing advance is calculated by fix offset, a configured common TA value and UE specific TA adjustment (i.e., 6gNB estimated value, and the UE estimated value using GNSS).
- Proposal 3 (Sec NTN requirements): The UE specific TA adjustment should be considered for both terrestrial networks (TN)s as well as for non-terrestrial networks (NTN)s.
- Proposal 4 (Sec NTN requirements): Consider outcome of study on NR-NTN GNSS resilience in Rel. 20 NR as a baseline for designing the timing advance framework in 6GR.
- Proposal 5 (Sec New use cases and requirements): New lower numerology(ies) should be introduced in the 6GR at least for sub-1GHz bands to achieve better coverage along with 15KHz SCS. The lower numerology 7.5kHz should be considered as a candidate in the study phase.
- Proposal 6 (Sec FFT size for 6GR): The maximum supported FFT size from RAN1 perspective for study is as follows, 8192, 16384.
- Proposal 7 (Sec TDD configurations): For the study of 6GR TDD frame structure configuration / indication, support cell and UE/group specific configuration.
- Proposal 8 (Sec TDD configurations): Deprioritize dynamic TDD and DCI based slot format indication in 6G day 1.
- Proposal 9 (Sec TDD configurations): For 6GR slot formats, at least DL symbols, UL symbols, F symbols and SBFD symbols (where gNB operates in SBFD) are supported.
- Proposal 10 (Sec TDD configurations): In 6GR, indicating SBFD symbols along with DL and UL slots/symbols should be supported.
- Proposal 11 (Sec TDD configurations): The TDD configurations in 6GR should be designed to provide UE with link direction in a SBFD symbol.