Partial and Statistical CSI Based Precoding for Reduced‐cp OTFS with Inter‐slot‐interference Pre‐cancellation

This work studies the precoding methods for the reduced cycle-prefix (CP) orthogonal time frequency space (OTFS) modulation to simplify the receiver design. First, a system model is established which shows that there are both intra-slot-interference and inter-slot-interference in the reduced-CP OTFS system. Then, the precoding operation is proposed to pre-cancel the inter-slot-interference in the reduced-CP OTFS system so that the bit error rate (BER) performance can be greatly improved. According to how much channel state information (CSI) needs to be fed back, precoding methods for two different cases are proposed: the partial CSI feedback case and the partial and statistical CSI feedback case. Among them, the partial and statistical CSI based precoding method has very small feedback burden. Simulation results of the BER performance of the proposed precoding methods for reduced-CP OTFS are reported and compared under different system parameters.