Multi-Mode Aided OTFS Based Spatial Modulation System

Orthogonal Time Frequency Space (OTFS) mod-ulation has been proposed to provide better bit error rate (BER) performance over orthogonal frequency division multi-plexing (OFDM) under high-mobility wireless channels. In this paper, a multi-mode index modulation aided OTFS-based spatial modulation (MMIM-OTFS-SM) system is proposed to improve spectral efficiency (SE) and transmission reliability in mobile communication environments. The proposed system exploits the benefits of MMIM, OTFS, and SM. Moreover, we discuss the discrete-input continuous-output memoryless channel (DCMC) capacity of the MMIM-OTFS-SM system. A framework for analyzing the average bit error rate (ABER) performance is also introduced. The analytical expression is validated through simulation results. Finally, our simulation results show that the proposed MMIM-OTFS-SM system performs well over conventional index modulation-based SM-OTFS schemes.