R1-2601907
discussion
Discussion on NTN specific issues for 6GR
From SageRAN
Summary
This document from SageRAN discusses NTN-specific issues for 6G Radio, presenting 2 Observations and 7 Proposals across five areas: initial TA command enhancement, frequency adjustment command, mobility measurement based on beam coverage, scheduling offset, and TDD frame structure.
Position
SageRAN proposes studying the possibility of negative TA command values in RAR for NTN random access when UE pre-compensation exceeds RTD, while leaving PRACH detection for over pre-compensation advance to gNB implementation and suggesting consideration of PRACH format with multi sequences. They suggest introducing a new frequency adjustment command to support closed-loop frequency control for NTN, analogous to timing advance control. They suggest introducing a new measurement configuration including beam properties (azimuth, elevation, beamwidth) because the existing location format without altitude information cannot meet high-altitude scenario requirements. They suggest Option 2 for scheduling offset in 6GR, where large scheduling delays to accommodate RTT are incorporated into scheduling offsets like K1/K2 in NR, and propose studying extension of dl-DataToUL-ACK to accommodate greater delay range. They also propose studying an efficient frame structure for TDD in NTN.
Key proposals
- Proposal 1 (Initial TA command enhancement): The possibility of negative value of TA command in RAR should be studied.
- Proposal 2 (Initial TA command enhancement): PRACH detection for over pre-compensation advance is left to gNB implementation. The PRACH format with multi sequences should be considered.
- Proposal 3 (Frequency adjustment command introduction): It is suggested that new frequency adjustment command should be introduced to support closed-loop frequency control for NTN.
- Proposal 4 (Mobility measurement based on beam coverage): It is suggested that a new measurement configuration should be introduced, which includes properties of beam, such as azimuth, elevation and beamwidth.
- Proposal 5 (Scheduling offset): Option 2 is suggested to be the solution of scheduling offset in 6GR.
- Proposal 6 (Scheduling offset): The potential extension of configuration dl-DataToUL-ACK should be studied to accommodate greater delay range.
- Proposal 7 (Frame structure for TDD): Efficient frame structure for TDD in NTN should be studied.