R1-2509144
discussion
6G frame structure and numerology
From MediaTek
Summary
This document contains 17 proposals and 11 observations from MediaTek on 6G frame structure and numerology. It covers numerology design (SCS, CBW, FFT size), support for contiguous bandwidth via multi-carrier cell, frame structure enhancements, and duplex mode evolution from NR.
Position
MediaTek proposes striving for a single numerology and single max CBW for a given duplex mode in the ~1GHz-10GHz range, with maximum UE CBW set to 200MHz around 7GHz and max FFT size restricted to 8192 points. For contiguous bandwidth larger than 200MHz, MediaTek presents a technical case for a multi-carrier cell (MC cell) solution that decouples the one-to-one mapping between physical carrier and logical cell, arguing this achieves lower implementation cost/complexity and higher maximum attainable SNR than an ultra-wide single carrier while avoiding SCell activation/deactivation latency present in legacy CA. Regarding frame structure, MediaTek proposes studying PXSCH across slot boundary to enhance coverage and reduce latency, and questions the necessity of symbol-level TDD flexibility in 6G. For duplex, MediaTek requires defining only D symbols, U symbols, and guard period for TDD operation, opposes the need for Flexible symbols, and requires UE-specific link direction indication for SBFD symbols to avoid the UE complexity issues observed in NR dynamic TDD.
Key proposals
- Proposal 1 (Sec 2.1): For a given duplex mode, strive for single numerology (incl. SCS and CP) in a spectrum range in 6G, especially for ~7GHz spectrum range.
- Proposal 3 (Sec 2.1): Max FFT size is restricted to 8192 points for 6G.
- Proposal 5 (Sec 2.2): For around 15GHz spectrum range, further study the feasibility of 30KHz and 60KHz SCS, considering max 1024QAM with max 6 or 8 MIMO layers, UE speed 3/30/60/120 km/hr and 30/100/300 ns delay spread of indoor and outdoor scenarios (30kHz is slightly preferred by MediaTek).
- Proposal 4 (Sec 2.2): For all SCS, only normal CP is supported in 6G.
- Proposal 6 (Sec 2.3): RAN1 to study multi-carrier cell solution to support contiguous spectrum >200 MHz around 7 GHz for UE.
- Proposal 8 (Sec 3): Study the support of PXSCH across slot boundary to enhance coverage and reduce latency.
- Proposal 9 (Sec 3): Study whether symbol-level flexibility of TDD UL/DL configurations is needed in 6G, considering the identified use cases.
- Proposal 10 (Sec 4): Target both FD-FDD and HD-FDD operation at UE side for paired bands.
- Proposal 11 (Sec 4): Target semi-static TDD operation in unpaired bands as a baseline, with consideration for CLI mitigation for asynchronous semi-static TDD scenarios.
- Proposal 13 (Sec 4): For TDD operation in 6G, define only D symbols, U symbols, and guard period.
- Proposal 14 (Sec 4): If dynamic TDD to be supported, 6G should adopt the indication of a TDD pattern out of predefined TDD patterns. No need to support Flexible symbols. The UE should be provided with sufficient processing time to apply the TDD pattern change.
- Proposal 15 (Sec 4): Study TDD enhanced with SBFD as a fundamental 6G design component for unpaired bands.
- Proposal 16 (Sec 4): If network-side SBFD is supported in 6G, link direction should be provided to the UE (half-duplex UEs).
- Proposal 17 (Sec 4): Study UE-side SBFD on top of network-side SBFD for 6G.