R1-2509056
discussion
Frame Structure for 6GR
From Sharp
Summary
Sharp's R1-2509056 provides 8 proposals and 19 observations on 6G Radio (6GR) frame structure, covering numerology, bandwidth support, duplexing, TN/NTN harmonization, and multi-RAT spectrum sharing (MRSS) with 5G NR. The document takes existing 5G NR agreements as its baseline and proposes specific study areas for 6GR physical layer design.
Position
Sharp proposes studying 7.5kHz SCS specifically for NTN, citing doubled symbol duration over 15kHz for better tolerance to LEO/MEO satellite delay spread and Doppler. They support studying 400MHz bandwidth around 7GHz using multiple implementation options including single carrier with multiple FFT operations or carrier aggregation, noting 16K FFT complexity challenges for UEs. Sharp requires native support of SBFD and forward-compatible duplexing frameworks rather than patch-like Rel-19 solutions, and proposes studying both cell-specific and UE-specific RRC configuration mechanisms for frame structure. They advocate adopting a harmonized TN/NTN frame structure design principle while initiating study on NTN-specific adaptations such as longer TDD pattern periods. Sharp proposes supporting DMRS bundling and TBoMS features from Day 1, and studying efficient MRSS with aligned numerology and resource grid assumptions between 5G NR and 6GR.
Key proposals
- Proposal 1 (Sec 2): Support studying SCS value of 7.5kHz for NTN; any CP values other than normal CP should allow alignment of time-domain boundaries at the level of one or multiple symbols; consider additional FFT sizes such as 8K and 16K.
- Proposal 2 (Sec 2): Study methods for enabling UE to support 400MHz bandwidth around 7GHz with 30kHz SCS, e.g., single carrier with single or multiple FFT operations as well as carrier aggregation approaches.
- Proposal 3 (Sec 2): Consider wider bandwidths such as 200 MHz for FR1 above 2 GHz and new frequency bands around 7 GHz, as well as over 400 MHz in FR2, possibly up to 800 MHz for FR2-1.
- Proposal 4 (Sec 2): Study native support of SBFD and forward-compatibility with future duplexing schemes to allow minimum effort at later releases.
- Proposal 5 (Sec 2): Study 6GR frame structure configuration/indication mechanisms to support both cell and UE specific RRC configuration.
- Proposal 6 (Sec 2): Adopt the design principle of harmonized/unified frame structure for TN and NTN; and initiate the study on the necessity and feasibility of frame structure specificities for NTN.
- Proposal 7 (Sec 2): Support features similar to DMRS bundling and TBoMS on Day 1.
- Proposal 8 (Sec 2): Study efficient MRSS by making simplified alignment assumptions such as aligned numerology and resource grid.