Reduced complexity algorithm for combined equalization and decoding for channels with multipath, ISI or partial response

This paper presents a new suboptimal algorithm for combined equalization and decoding. This algorithm can provide much better performance with the same order of complexity than the Reduced States Sequence Estimator (RSSE). The algorithm, termed Estimated Future decision Feedback Algorithm (EFDFA), was originally proposed for the problem of noncoherent decoding with multiple-symbol overlapped observations and is now reformulated for the problem of ISI inflicted channels. The EFDFA uses the RSSE as a building block. The performance of the overall algorithm is much better than the RSSE part alone. The performance improvement is achieved by using estimated future symbols in the decision process. The future symbols are estimated by RSSE decoding time-reversed blocks of the input. An analysis of the performance of the EFDFA based on the performance of the RSSE is introduced.