Near Optimal Timing and Frequency Offset Estimation for 5G Integrated LEO Satellite Communication System
Autor: | Li You, Xiqi Gao, Tong Yushan, Li Lingxuan, Wenjin Wang, An-An Lu |
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Rok vydání: | 2019 |
Předmět: |
LEO satellite
General Computer Science Computer science Orthogonal frequency-division multiplexing Air interface General Engineering 020302 automobile design & engineering 020206 networking & telecommunications time and frequency synchronization 02 engineering and technology Synchronization Cyclic prefix 0203 mechanical engineering Telecommunications link 0202 electrical engineering electronic engineering information engineering Communications satellite Electronic engineering Doppler shift Frequency offset General Materials Science lcsh:Electrical engineering. Electronics. Nuclear engineering 5G integrated network lcsh:TK1-9971 5G |
Zdroj: | IEEE Access, Vol 7, Pp 113298-113310 (2019) |
ISSN: | 2169-3536 |
DOI: | 10.1109/access.2019.2935038 |
Popis: | The integration of satellite and terrestrial 5G networks aims to provide ubiquitous coverage, improve service reliability, and enable the network scalability. However, the inherent characteristics of satellite channels bring challenges on the air interface design of integrated terrestrial-satellite networks. For example, for low earth orbits (LEO) mobile satellite communication (SatCom) system, it is unclear so far whether the 5G new radio (5G-NR) synchronization signals could meet the requirement of timing and frequency offset estimation in the presence of large Doppler shifts. In this paper, we investigate time and frequency synchronization for the downlink transmission of 5G-NR signals over LEO satellite channels. Starting from the maximum log-likelihood criterion for timing offset estimation given the observation of the received primary synchronization signals (PSS), we derive an upper bound of the objective function for simplicity. With a priori information that the maximum Doppler shift of LEO satellite-ground link is within a specific range, we construct the local synchronization sequence via using the modulated discrete prolate spheroidal sequences (DPSS) vectors. Then the timing offset estimation can be recast into a one-dimensional peak search problem. Moreover, the cyclic prefix (CP) structure of orthogonal frequency division multiplexing (OFDM) can be utilized to improve the estimation performance further. Once the timing and frequency offset are captured in the above initial synchronization phase, the tracking synchronization can be much simplified as the variation of both the timing and frequency offset is very small between two adjacent synchronization blocks. Simulation results show that by using the proposed algorithms, the 5G-NR signals can achieve near optimal downlink time and frequency synchronization in typical LEO SatCom systems. |
Databáze: | OpenAIRE |
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