R1-2509140
discussion
Discussion on 6GR frame structure
From KT
Summary
KT Corp. provides views on 6GR frame structure design, covering SCS, bandwidth, FFT size, duplexing, and multi-RAT spectrum sharing. The document contains 1 observation and 4 proposals aimed at simplifying 6G NR design based on lessons learned from 5G NR deployments.
Position
KT proposes adopting a single representative SCS per frequency band for 6GR to reduce implementation complexity, with specific pairings: 15kHz SCS/8K FFT for Sub-6GHz FDD at 100MHz, 30kHz SCS/8K FFT for Sub-6GHz TDD at 200MHz, 60kHz SCS/8K FFT for 15GHz at 400MHz, and 120kHz SCS/4K FFT for 24.25-52.6GHz at 400MHz. They deprioritize UE-specific TDD configuration and Dynamic SFI for 6GR TDD operation, arguing these features caused excessive complexity in 5G NR and were rarely utilized in practical deployments. For duplexing, they propose introducing SBFD as a native symbol type in TDD configuration rather than requiring additional conversion from DL/F symbols as done in NR Rel-19, with further study on gNB dynamic SBFD for time-domain ON/OFF switching. For multi-RAT spectrum sharing, they propose studying symbol-level aligned numerologies between 5G and 6G based on NCP to enable simplified time-frequency compatibility.
Key proposals
- Observation 1 (Sec 2.1): SCS design impacts UE/gNB implementation complexity and is influenced by ISI and ICI characteristics that vary across frequency bands.
- Proposal 1 (Sec 2.1): RAN1 to study 6GR maximum carrier bandwidth, SCS, and FFT size with specific parameters per band: Sub-6GHz FDD (100MHz, 15kHz SCS, 8K FFT), Sub-6GHz TDD (200MHz, 30kHz SCS, 8K FFT), 15GHz (400MHz, 60kHz SCS, 8K FFT), 24.25-52.6GHz (400MHz, 120kHz SCS, 4K FFT).
- Proposal 2 (Sec 2.2): RAN1 to study semi-static cell-common TDD configuration for 6GR TDD operation, with UE-specific TDD configuration and Dynamic SFI deprioritized.
- Proposal 3 (Sec 2.2): RAN1 to study TDD configuration including SBFD symbol as an independent native symbol type alongside DL, UL, and F symbols for 6GR duplexing, with FFS on time domain gNB dynamic SBFD.
- Proposal 4 (Sec 2.3): RAN1 to study 5G-6G aligned numerology with compatible SCS for multi-RAT spectrum sharing (MRSS).