Bidirectional fractionally-spaced decision feedback equalizer based on soft outputs combination

Abstract

The bidirectional fractionally-spaced decision feedback equalizer (DFE) based on the soft outputs combination is proposed. Without any channel estimation, the fractionally-spaced DFE effectively compensates for any phase distortion and suppresses the error propagation. Compared to conventional methods, the soft outputs combining scheme involving the log likelihood ratios (LLRs) of two DFEs outputs running in opposite directions achieves much better performance in diversity gain. The simulation results demonstrate that the proposed method outperforms the conventional bidirectional DFE by 2∼4 dB over Proakis B channel.