A new post-viterbi processor based on soft-reliability information

This paper proposes a soft-reliability information-based post-Viterbi processor for reducing miss-correction of an error correlation filter-based post-Viterbi processor. The essential difference between the soft-reliability information-based and the error correlation filter-based post-Viterbi processors, is how to locate the most probable error starting position. The new scheme determines an error starting position based on a soft-reliability estimate, while the conventional scheme chooses an error starting position based on likelihood value. Among all likely error starting positions for prescribed error events, the new scheme attempts to correct error-type corresponding to the position only if there exists a position where the soft-reliability estimate is negative, while the conventional scheme performs error correction based on error-type and its error starting position of an error event associated with the maximum likelihood value. A correction made by the conventional scheme may result in miss-correction because the scheme does not have any criterion for judgment whether an estimated error starting position is correct. In case error correction is only performed when a position with negative soft-reliability estimate exists, the probability of miss-correction of the new scheme is less than the one of the conventional scheme.