Soft-output decoding for concatenated error correction in high-order PRML channels

A soft-output decoding scheme was developed for the cyclic-redundancy-check error-correction-code (CRCC) concatenated error correction by applying the list and soft-symbol-output Viterbi algorithm (list-SOVA). By focusing on just the specified dominant error-events in the maximum-likelihood (ML) sequence detector, a soft-output data-reliability generator and a list generator were efficiently simplified for soft-output decoding. The soft-output decoding enables multiple dominant error events within a data block to be corrected without increasing the CRCC redundancy and modifying the CRCC structure. It can also help prevent the CRCC miscorrection when correcting the multiple error-events. It was confirmed that the soft-output decoding with a reasonably sized data-block list can perfectly correct the double error-events within a data-block on a 16/17 rate quasi-MTR-coded modified E/sup 2/PRML (ME/sup 2/PRML) channel at a practical error-rate.