Performance Analysis of MIMO-OTFS with Advanced Detection Techniques for High-Mobility Wireless Communication

Orthogonal Frequency Division Multiplexing (OFDM) has been the dominant multicarrier transmission technique in wireless communication; however, its susceptibility to inter-carrier interference and Doppler spread limits reliability under high-mobility conditions. Orthogonal Time Frequency Space (OTFS) modulation, in contrast to conventional time–frequency domain schemes, transforms information symbols into the delay–Doppler (DD) domain via a symplectic finite Fourier transform. This enables the effective exploitation of the channel’s inherent sparsity and enhancing robustness against doubly selective fading effects. Extending this framework, a Multiple-Input Multiple-Output (MIMO)-OTFS system is developed to enhance spatial diversity and throughput in rapidly varying propagation environments. Specifically, this study investigates the Bit Error Rate (BER) performance of OTFS under the Extended Vehicular A (EVA) channel model. The results are benchmarked against conventional Orthogonal Frequency Division Multiplexing (OFDM) operating over a Rayleigh fading channel. The scope of the analysis is broadened to encompass MIMO-OTFS systems with 2×2 configuration, an Expectation Propagation (EP)-based detection strategy, and a Deep Learning (DL)-oriented detection framework. The robustness of the MIMO-OTFS system is further substantiated through simulations conducted across diverse mobility conditions, with consistent performance observed even at vehicular velocities reaching 120 km/h. Additionally, this work examines the incorporation of Non-Orthogonal Multiple Access (NOMA) into the MIMO-OTFS framework. The MIMO-OTFS-NOMA configuration, particularly for users with favorable channel conditions (near users), exhibits exceptional BER performance. The SE versus SNR curves confirm that DL-aided MIMO-OTFS achieves the best trade-off between reliability and efficiency. Collectively, the results underscore the potential of MIMO-OTFS, as a highly resilient and spectrally efficient solution for next-generation wireless systems operating under severe channel time variability and mobility constraints.