Iterative Decision-Feedback Hybrid Equalization for CP-OTFS on Time-Varying Multipath Channels

Cyclic-prefix orthogonal time frequency space (CP-OTFS) systems have gained great attention recently due to achievable prominent error performance characteristics in high-mobility wireless communication scenarios and the system realizability by use of efficient Discrete Fourier transform. In this paper, a symbol decision scheme is proposed for the CP-OTFS system by virtue of iterative decision-feedback hybrid equalization (IDFHE) using time-domain linear minimum mean-square-error (LMMSE) and constrained least square (CLS) equalizers at different iterations. The proposed IDFHE scheme can exploit the advantage that intersymbol interference is suppressed progressively over iterations and noise power enhancement is avoided at the final iteration, and thereby enhance the error performance. From simulation results, the proposed IDFHE scheme is shown to outperform non-iterative LMMSE decision scheme and iterative message-passing symbol decision scheme in average error performance on time-varying Rayleigh multipath channels.