Low-Complexity LMMSE Receiver for Practical Pulse-Shaped MIMO-OTFS Systems

Orthogonal time frequency space (OTFS) modulation establishes reliable communication over highly time-varying wireless channels. This work designs a low-complexity linear minimum mean square error (LMMSE) receiver for practical pulse-shaped multiple-input multiple-output (MIMO)-OTFS systems. The proposed design reduces complexity by exploiting inherent channel sparsity and channel-agnostic structure of matrices involved in the LMMSE receiver. The proposed design, with log-linear complexity order, does not make any approximation, and provides exactly the same solution, and consequently the same bit error rate, as that of the conventional LMMSE receiver, which has a cubic complexity order.