Abstract: In order to cope with the complex channel environment in LEO satellite communication networks and eliminate the interference caused by time offset and carrier frequency offset, a time-frequency synchronization algorithm oriented to orthogonal time sequence multiplexing (OTSM) modulation technology is proposed. The time synchronization algorithm based on two-dimensional search uses the periodicity of the pilot signal in the delay-time domain to perform a sliding correlation search pilot sequence in the delay and time dimensions to estimate the time offset of the received signal. The frequency synchronization algorithm based on the two-dimensional correlation function estimates the carrier frequency offset of the received signal by calculating the phase of the two-dimensional correlation function value of the pilot sequence. The simulation results show that the proposed time-frequency synchronization algorithm has good BER performance in the satellite-ground scenario.

Key words: low earth orbit satellite, orthogonal time sequence multiplexing, time synchronization, frequency synchronization, correlation function