State reduced a result of estimation with use of in addition to groups distribution

摘要

The current invention describes how symbols may be allowed to straddle the region containing hypothesized symbols and the path history region, so that symbols exist partially in both states. This allows those parts of the symbol that are most important for predicting signal samples to be retained in the hypothesized state while the remaining parts can pass to the path history. A decoder that decodes a signal modulated with information symbols belonging to an alphabet of symbols. The decoder comprises a maximum likelihood sequence estimator that hypothesizes alphabetic sub-groups containing the information symbols, to hypothesize symbols within the alphabet and to determine a sequence of the information symbols having a highest likelihood indication. The decoder also includes a channel estimator to estimate coefficients describing a channel through which the signal has propagated, a signal predictor that combines the channel estimates with corresponding samples of the signal to obtain a metric and a metric accumulator to accumulate the metrics for hypothesized symbol sequences to determine the likelihood indications.