Improved Block Soft Feedback Equalization Based on Sequence Detection

A low complexity block soft feedback equalization based on sequence detection is presented for turbo equalization. The proposed algorithm can be used in the channel equalizer for calculation of the a posteriori probability (APP) by collecting information of the entire block as in MAP algorithm. The sequence-based detection is made possible by combining both soft a priori information from channel decoder and soft feedback from block decision feedback equalization (BDFE). Compare with the hard feedback, the soft feedback reduces the effects of the error propagation and leads to better performance. Simulation results show that the new equalizer outperforms the BDFE with hard feedback with a complexity similar to linear minimum mean square error (MMSE) equalizers.