Decision-aided sequential intersymbol interference sequence estimation for channels

A decision-aided sequential search algorithm is presented for the recovery of digital signals corrupted by intersymbol interference. An altered form of the Fano algorithm using information derived from an independent decision-feedback equalizer is shown to achieve near-maximum-likelihood performance with a lower computational complexity than that of the Viterbi algorithm at high signal-to-noise ratios. Simulated probability-of-error and computational complexity curves are presented. The Fano metric for sequential sequence estimation (SSE) on intersymbol interference (ISI) channels with Gaussian noise is derived. A suboptimum constant bias metric, similar to the Viterbi Euclidean distance metric, is studied. The SSW algorithm is shown to be effective for channels which have severe ISI