Reduced-Complexity Cross-Domain Iterative Detection for OTFS Modulation via Delay-Doppler Decoupling

TL;DR

This paper introduces a low-complexity iterative detection method for OTFS modulation that leverages channel properties in time and delay-Doppler domains, achieving near-optimal error performance with reduced computational effort.

Contribution

The paper proposes a novel cross-domain iterative detection scheme for OTFS that exploits channel structures to reduce complexity while maintaining high detection accuracy.

Findings

Achieves near-optimal error performance

Reduces computational complexity significantly

Validates effectiveness through simulations

Abstract

In this paper, a reduced-complexity cross-domain iterative detection for orthogonal time frequency space (OTFS) modulation is proposed, which exploits channel properties in both time and delay-Doppler domains. Specifically, we first show that in the time domain effective channel, the path delay only introduces interference among samples in adjacent time slots, while the Doppler becomes a phase term that does not affect the channel sparsity. This ``band-limited'' matrix structure motivates us to apply a reduced-size linear minimum mean square error (LMMSE) filter to eliminate the effect of delay in the time domain, while exploiting the cross-domain iteration for minimizing the effect of Doppler by noticing that the time and Doppler are a pair of Fourier dual. The state (MSE) evolution was derived and compared with bounds to verify the effectiveness of the proposed scheme. Simulation results demonstrate that the proposed scheme achieves almost the same error performance as the optimal detection, but only requires a reduced complexity.