Successive Interference Cancellation Aided Bidirectional Soft Decision Feedback Equalization for OTFS Systems

Soft decision feedback equalization (SDFE) paradigms are conceived for the orthogonal time frequency space (OTFS) modulation in this letter. The proposed schemes are performed by reconstructing the delay-Doppler (DD)-banded channel matrix, while the successive interference cancellation (SIC) and soft decision feedback techniques are exploited for mitigating inter-symbol interference (ISI). Moreover, the SDFE is beneficially amalgamated with the bidirectional structure, yielding the bidirectional SDFE (Bi-SDFE). Explicitly, by combining the forward and backward SDFEs' outputs, the proposed Bi-SDFE is capable of attaining both bidirectional diversity and error propagation mitigation. It is demonstrated that the convergence-enhanced Bi-SDFE can attain a better bit error ratio (BER) performance compared to some existing solutions.