A Simple Two-Stage Equalizer for OTFS With Rectangular Windows

Orthogonal time-frequency space (OTFS) bears the potential to achieve excellent performance in high mobility scenarios. However, conventional linear equalizer performs poorly. In this letter, we propose a novel two-stage equalizer, wherein received signals are judiciously processed in two domains. First, in the time-frequency domain, a sliding window-assisted minimum mean square error (SW-MMSE) equalizer is proposed to restrict the inter-carrier interference effectively. Then in the second stage, a delay-doppler domain equalizer further mitigates the residual inter-symbol interference of the first stage. Our proposed two-stage equalizer enjoys low implementation complexity, and simulation validates its performance advantage over the conventional one-stage MMSE equalizer.