Iterative Symbol Decision Schemes for CP-OTFS on Static Multipath Channels

Orthogonal time frequency space (OTFS) systems have gained great attention in wireless communications due to achievable prominent error performance characteristics on high-mobility and static multipath channels. In this paper, two symbol decision schemes are proposed for the cyclic-prefixed OTFS system on static multipath channels by virtue of iterative decision-feedback hybrid equalization (IDFHE) using linear minimum mean-square-error (LMMSE) equalization rule and message-passing algorithm (MPA) as the respective first-iteration decision rule. The proposed LM-IDFHE and MPA-IDFHE schemes can exploit the advantages that inter-symbol interference is suppressed progressively over iterations and noise power enhancement is avoided at the final iteration. From simulation results, LM-IDFHE and MPA-IDFHE schemes are shown to outperform non-iterative LMMSE, iterative LMMSE, and iterative MPA schemes remarkably in average error performance on Rician multipath channels.