A Low-Complexity Adaptive Confidence Decision Equalizer for ZP-OTFS Systems

Orthogonal time frequency space (OTFS) modulation has emerged as a promising candidate for high-mobility communications. However, designing a low-complexity OTFS equalizer under fractional Doppler shift remains challenging. This letter proposes a low-complexity adaptive confidence decision (LC-ACD) equalizer to tackle this issue. Specifically, we devise an adaptive confidence region based on the zero-padded (ZP) symbols. Furthermore, a low-complexity likelihood ascent search (LC-LAS) equalizer is developed. In doing so, the ZP confidence region with parallel interference cancellation is employed to reconstruct the equalization parameters for the achievement of fast detection and performance gain. Simulation results demonstrate that the LC-ACD equalizer strikes a superior detection performance with lower complexity.