Study on OTFS Channel Estimation Algorithms in High-Speed Mobile Communication Systems

In view of the problem that dual-dispersion channels will reduce the reliability of channel estimation in high-speed mobile environments, a channel estimation algorithm based on compressed sensing is proposed in the input-output model of Orthogonal Time-Frequency-Space (OTFS) modulation system. The maximum Doppler shift and the maximum delay in the channel are employed to determine the size of the pilot transmission matrix in the algorithm. Compared with the traditional Orthogonal Matching Pursuit (OMP) channel estimation algorithms, the pilot resources can be saved in the proposed algorithm while the accuracy of similar channel estimation is guaranteed. Furthermore, the phase rotation of the OTFS modulation symbols is used to improve the rank of the differential matrix. Theoretical analysis and simulation results show that the diversity order of the OTFS system is improved and noise interference is reduced.