Uplink Time Synchronization Method and Procedure in Release-17 NR NTN
Wenjia Liu, Xiaolin Hou, Jing Wang, Lan Chen, Shohei Yoshioka
Abstract
Non-terrestrial network (NTN) is an important technique to provide extreme coverage. Current fifth-generation (5G) new radio (NR) techniques mainly focus on the terrestrial networks. How to support NTN by 5G NR techniques is studied in 3rd generation partnership project (3GPP) since Release 15. After extensive studies, the first release of NR NTN is finished in Release 17. Uplink time synchronization is an important topic for both terrestrial networks and NTN, without which the interference among multiple users as well as the uplink and downlink misalignment will happen. Different from 5G NR, open-loop timing advance (TA) including common TA and UE-specific TA is firstly introduced in NR NTN. This paper introduces the latest progress in Release 17 and gives the solutions, procedures, and evaluation results for uplink synchronization in NR NTN.