R1-2508651
discussion
6GR frame structure
From InterDigital
Summary
This document from InterDigital contains 11 proposals and 3 observations on the 6G Radio (6GR) frame structure, covering numerologies (CP types), frame format configurations with a new 'X' symbol/slot type for native SBFD support, duplex schemes including dynamic TDD and dynamic SBFD, scheduling unit flexibility, and Multi-RAT Spectrum Sharing (MRSS) alignment with 5G NR.
Position
InterDigital proposes that 6GR only supports normal CP length, arguing that extended CP is unjustified for sub-7GHz deployments with SCS up to 30 kHz and for NTN scenarios. They define a new 'X' symbol/slot type to natively support SBFD operation, replacing NR Rel-19's override-based design with a unified signaling structure and providing forward compatibility toward dynamic-TDD and dynamic-SBFD. They present SLS results showing that semi-static SBFD suffers from severe DL 5%-ile UPT losses (over 80-90% at high load) due to UE-UE CLI, and propose studying gNB-side dynamic SBFD where dynamic fallback of UL subband resources to DL can enhance both DL and UL throughput. They require PDSCH and PUSCH transmissions to not be constrained within a single slot and support symbol-level scheduling as a unified minimum scheduling unit. They require symbol-level and PRB-level resource-grid alignment plus aligned TDD patterns between 5G NR and 6GR for MRSS without additional guard intervals.
Key proposals
- Proposal 1 (Sec 2.1): 6GR only supports normal CP length for communication.
- Proposal 2 (Sec 3.1): Support three primary symbol/slot types ('D', 'U', 'X') in 6GR frame format configuration or indication, to natively support SBFD and ensure extensibility to dynamic-TDD and dynamic-SBFD operations.
- Proposal 3 (Sec 3.1.1): Support at least dynamic TDD and gNB semi-static SBFD for 6G Day-1.
- Proposal 4 (Sec 3.1.1): Support dynamic indication of frame pattern for dynamic TDD.
- Proposal 5 (Sec 3.1.1): Support UE-specific configuration and indication of frame pattern.
- Proposal 6 (Sec 3.1.1): Study gNB-side dynamic SBFD as a duplex enhancement scheme for 6GR.
- Proposal 7 (Sec 3.2): PDSCH and PUSCH transmissions are not constrained to a slot.
- Proposal 8 (Sec 3.2): 6GR supports symbol level scheduling.
- Proposal 9 (Sec 3.2): 6GR supports dynamic indication of PDCCH-to-PDSCH scheduling offset.
- Proposal 10 (Sec 4): Support symbol-level and PRB-level resource-grid alignment between 5G NR and 6GR frames for MRSS.
- Proposal 11 (Sec 4): Support aligned TDD patterns between 5G NR and 6GR, including common DL/UL switch points for MRSS.