R1-2600048
discussion
On NTN specific requirements and design for GNSS based operation in 6GR
From Nokia
Summary
Nokia's contribution proposes 11 specific items and 2 observations for 6G Radio NTN design, emphasizing a harmonized TN/NTN framework with GNSS-dependent operation, limited NTN-specific features, and studies on HARQ stalling mitigation and SIB scheduling improvements.
Position
Nokia requires that all 6GR devices support GNSS for NTN operation and that 6GR systems support NTN from day one with maximum similarity to the terrestrial network (TN) design. They insist NTN-specific features must only be introduced when strictly necessary, such as UE autonomous pre-compensation of time/Doppler offsets, while enhancements originating from NTN (e.g., timing uncertainty, Doppler offsets, reduced link budget, large round trip time) shall be incorporated into the general 6GR design. Nokia opposes the Rel-18 network verified UE location feature unless it is accurate, trustworthy, and has mandatory UE support. They propose studying extended PDSCH/PUSCH transmission duration to combat HARQ stalling, and studying concurrent SIB1 and NTN access essential SIB scheduling to improve initial access latency and reliability. They calculate TDD efficiency losses of 14-31% for LEO orbits and therefore require that 6GR NTN studies focus on FDD duplex mode.
Key proposals
- Proposal 1 (Introduction): All 6GR devices are expected to support GNSS to facilitate 6GR NTN based operation.
- Proposal 4 (Considerations on learnings from NR over NTN work): Features like “Network verified UE location” should only be considered for NTN operation in 6GR systems if there is general support for making the feature accurate, trustworthy and having mandatory support from UE side.
- Proposal 5 (Considerations on learnings from NR over NTN work): NTN operation in 6GR system shall strive for maximum similarity to the 6GR TN system.
- Proposal 8 (Considerations on learnings from NR over NTN work): The 6GR NTN design shall also be able to provide services for devices that are not able to rely on their geo-location for performing pre-compensation of channel impairments.
- Observation 1 (Considerations on HARQ processing in 6GR NTN): HARQ disabling has large impact to link adaptation, spectral efficiency and packet delays, impacting UE throughput.
- Proposal 9 (Considerations on HARQ processing in 6GR NTN): Study extended duration of PDSCH and/or PUSCH transmissions targeting the problem of HARQ stalling in NTN.
- Proposal 10 (Considerations on NTN specific SIB in 6GR NTN): RAN1 to study mechanisms for concurrent scheduling of SIB1 and NTN access essential SIB system information.
- Proposal 11 (Duplex mode): NTN studies for 6GR should focus on FDD.
- Proposal 2 (Considerations on learnings from NR over NTN work): The 6GR system shall support NTN operation from day one.
- Proposal 3 (Considerations on learnings from NR over NTN work): NTN operation in the 6GR system shall carry most of the Rel-17 NR over NTN functionalities, including the assumption of a UE knowing its geo-location and NTN specific information needed for pre-compensation (e.g. 5G NR SIB19 related information).