A Doppler-Tolerant Synchronization Method for 5G NR-Based Non-Terrestrial Networks

An initial synchronization method robust to a large Doppler offset is required for user equipment (UE) in non-terrestrial networks (NTNs) based on new radio (NR) because of the high speed of low earth orbit (LEO) satellites. In this letter, a multiple differential correlation combining with different time offsets (MDCT) is proposed for initial synchronization at the UE in NTNs with a large Doppler offset, without changing the existing preamble in 5G NR. Autocorrelation and cross-correlation properties of the MDCT method are derived in the presence of a large carrier frequency offset (CFO). Simulation results in NTN channel environments shows that timing and cell ID can be detected correctly in the presence of a large CFO by the MDCT method. The proposed MDCT method is compared with the conventional methods based on correlation (5G NR) or differential correlation, and is found to provide better performance in multicell environments with a low computational complexity.