A Low-Complexity Message Passing Detector for OTFS Modulation With Probability Clipping

The recently proposed orthogonal time frequency space (OTFS) modulates the data in the delay-Doppler domain, thereby the 2-D diversity gain can be obtained to improve the communication performance over time-varying channels. However, the matrix-inversion based detectors have pretty high complexity in OTFS systems due to the large size of channel matrix. This letter proposes a low complexity matched filtering based message passing detector (MF-MPD), combined with a novel probability clipping (PC) solution. Benefit from matched filtering processing, the complexity and storage requirement of this solution can be reduced, and better BER performance in low SNR regimes can be achieved. Furthermore, the BER floor at high SNRs can be obviously improved via PC over time-varying channels according to the numerical results.