OTFS-Modulated MIMO Faster-than-Nyquist Signaling in Doubly Selective Fading Channel

This paper proposes a novel reduced-complexity detection scheme for multiple-input multiple-output (MIMO)-assisted faster-than-Nyquist (FTN) signaling scheme in the doubly selective fading channels. By utilizing the channel’s sparse approximation, we exploit a simplified linear minimum mean square error (LMMSE) algorithm with a log-linear complexity. The proposed scheme attains the same bit error rate performance as the conventional LMMSE detector while attaining a significantly lower complexity. Furthermore, we propose the amalgamation of MIMO-FTN signaling and orthogonal time frequency space modulation and conceive the low-complexity delay Doppler domain detection algorithm by exploiting the channel’s sparsity.