FUTUREWEI · 10.7.1

Futurewei proposes that RAN1 agree on a 100% satellite beam footprint coverage ratio before proceeding with studies on beam footprint versus active beam mismatch, and suggests that simultaneous active beams may be as low as 1.5% of total beams per satellite across all frequency bands. They present a technical case showing that with current assumptions (160 ms SSB periodicity, one SSB/PBCH block per half radio frame), only 1024 out of 2134 beams can be covered, yielding 48% coverage—insufficient for full footprint coverage. They propose studying the impact of both static and dynamic beam hopping patterns on UE performance in idle and connected modes, specifically identifying the SSB index / PRACH preamble collision problem in adjacent beams as a performance-affecting factor. They also indicate that 6GR NTN uplink time-frequency synchronization should follow the Rel-19 NR NTN GNSS-based pre-compensation methodology as baseline, allowing RAN1 to focus on 6GR NTN-specific issues rather than duplicating Rel-20 GNSS resilient NR-NTN study work.

Futurewei proposes studying Very Low Earth Orbit (VLEO) NTN scenarios at an orbital height of 300 km for 6GR, while defaulting to Rel-17 NR-NTN LEO and GEO parameters for other cases. To mitigate the increased UE power consumption from GNSS-based NTN operation, they propose considering GNSS position fix time intervals and satellite elevation angles in the 6GR PRACH format design. They recommend studying network-controlled timing advance adjustments in both positive and negative directions during random access to correct GNSS position errors. Finally, they propose studying closed-loop frequency control to allow the network to adjust UE carrier frequency for correcting UE-specific frequency compensation errors during random access and in RRC connected mode.