Transmit diversity scheme design for rectangular pulse shaping based OTFS

This paper investigates the transmission scheme of the orthogonal time frequency space (OTFS) system with multiple antennas. Previous works have studied the multi-antenna transmitter diversity scheme with the ideal pulse shaping in OTFS systems assuming the wireless channels of two consecutive frames duration are invariant. However, the ideal pulse shaping can not be realized in practice and the channel varies rapidly in two consecutive frames in the high-speed mobility scenarios. To this end, we redesign the multi-antenna transmitter diversity scheme to ensure its practicability in the rectangular-pulse-based OTFS systems. At first, the information symbols of each antenna are divided into two half frames along the Doppler domain. Then, the guard symbols are carefully arranged to eliminate the interference between two half frames, and to ensure the equivalent channels of two half frames being identical. By considering the positions of the guard symbols, the transmission codeword is designed and a low complexity linear detection is proposed. Finally, simulation results validate that the bit error rate performance of the proposed scheme has the superiority over the existing works.