A Frequency Offset Independent Timing Synchronization Method for 5G Integrated LEO Satellite Communication System

In this paper, a frequency offset independent timing synchronization method is proposed to solve the large frequency offset problem for the 5G integrated low-earth-orbits (LEO) satellite communication (SatCom) system. Firstly, a frequency offset independent timing metric is designed. Without changing the frame structure of NR and based on the conjugate symmetry of the primary synchronization signal (PSS) time-domain sequence, the received PSS sequence times its time-inverse sequence to construct a product sequence, each element of which has the same phase. And the phase can be canceled by the absolute value operation. Secondly, a delay-superposition method is used to improve the performance of the designed timing metric. The detection threshold can be improved further by accumulating the correlation peak value of each PSS in the SSB burst, and the number of superpositions can be selected flexibly to adapt the link-budget of the LEO SatCom system. The simulation results show that the proposed method maintains a high detection probability with increase of the frequency offset. Compared with the M-part PSS cross-correlation algorithm, the proposed method can improve 49% detection probability at −6dB when the frequency offset is as large as 600kHz.