Bidirectional Soft-Decision Feedback Equalization for OFDM Systems

A bidirectional soft-decision feedback equalizer (BiSDFE) for orthogonal frequency-division multiplexing (OFDM) systems over doubly selective channels Is proposed. Soft, rather than hard, decision feedback equalizer (SDFE) Is adopted to suppress Intercarrier Interference (iCi) and the band structure of the frequency-domain channel matrix Is exploited to trade off between performance and computational complexity. By combining a conventional SDFE with a frequency-reversed SDFE, the proposed scheme can eliminate ICi Induced by neighboring subcarriers of both sides, thereby obtaining frequency-reversal diversity and mitigating error propagation. Simulation results have demonstrated the advantage of this approach In bit error rate (BER), especially In the channels with large Doppler spreads.