Channel Reconstruction for Thp-Otfs Systems

The design of detection algorithms for orthogonal time-frequency space (OTFS) has always been a challenge. A new system model is proposed that uses Tomlinson-Harashima Precoding (THP) at the transmitter instead of the equalisation at the receiver. The performance of the system is improved while the complexity of the receiver is reduced significantly. In this paper, we analyse the system performance of the THP-OTFS system and derive the Bit Error Rate (BER) formula. Then we propose a method to reconstruct the channel by adding a filter at the transmitter, using the Sequential Quadratic Programming algorithm to compute suitable filter tapping coefficients in order to improve the main path power ratio of the reconstructed channel, thus improving the system performance. We compare the BER performance of our scheme and the Delay-Doppler (DD) domain linear minimum mean square error equalisation. Simulation results show that our scheme enhances the performance while keeping a low complexity.