Timing Advance-based Time Synchronization method in LEO Satellite Communication
- 주제(키워드) LEO , satellite communication , timing advance
- 주제(DDC) 004.6
- 발행기관 아주대학교 일반대학원
- 지도교수 김재현
- 발행년도 2026
- 학위수여년월 2026. 2
- 학위명 석사
- 학과 및 전공 일반대학원 AI융합네트워크학과
- 실제URI http://www.dcollection.net/handler/ajou/000000035802
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
Non-terrestrial networks (NTNs) utilizing low Earth orbit (LEO) satellites have gained significant interest due to their potential to provide seamless global coverage and low latency. However, LEO satellites require accurate timing advance (TA) pre-compensation considering the variation of propagation delay due to their high speed. In particular, random access channel-less (RACH-less) handovers require precise initial TA pre-compensation, as timing adjustments during the random access procedure cannot be performed. In NTN environments, system information block (SIB) 19 provides the relevant parameters for the common TA, which compensates for the feeder link round-trip time (RTT). However, the service link RTT must be compensated by the user equipment (UE) using its own location and the satellite's ephemeris data. To overcome these limitations, this thesis proposes an adaptive TA pre-compensation framework. When the ECEF update period is long, a simple 1st-order Taylor approximation becomes inaccurate due to the significant change in propagation delay. Therefore, this model adaptively applies either a 1st-order or a 2nd-order Taylor approximation based on the length of the ECEF update period. The proposed model allows the prediction of the propagation delay at the uplink (UL) transmission time based on the satellite's Earth-centered Earth-fixed (ECEF) coordinates at the epoch time. The predicted TA value ensures successful initial TA pre-compensation even in situations where TA adjustments are not possible, such as during RACH-less handovers. Through this method, reliable uplink synchronization can be achieved in LEO-based NTNs.
more목차
1 Introduction 1
1.1 Background and Motivation 1
1.2 Contributions 2
1.3 Overview 3
2 Related Works 4
2.1 Overview of timing advance in NTN 4
2.1.1 Timing advance formulation 4
2.1.2 TA according to satellite payload architecture 10
2.2 Uplink synchronization procedure 12
2.3 Recent research 15
3 Proposed TA pre-compensation method 17
3.1 Scenario 17
3.2 Proposed TA pre-compensation framework 18
3.2.1 Proposed TA pre-compensation procedure 18
3.2.2 Proposed initial TA pre-compensation method 20
4 Performance evaluation 28
4.1 System model 28
4.2 Performance metrics 30
4.3 Results and discussion 36
5 Conclusion 46
References 47
