| 摘要 |
A method and apparatus for decoding forward error correction (FEC) encoded data. A stream of units of FEC encoded bits are received, where the units are derived from a transmitted signal, where each unit represents a one-bit data value, and where each unit includes correctness bits that together reflect a level of probability that the one-bit data value represented by the unit differs from corresponding bits in the signal before it was transmitted. The stream of units of FEC encoded bits are decoded by using the quality level of bits to perform soft-decision convolution decoding on the stream of units of FEC bits, where the soft decision convolution decoding produces, for block decoding, a stream of symbols made up of bits. In the stream of units of FEC bits, subsequences of units that are prone to erroneous soft-decision convolution decoding are detected by determining, for the sub-sequences whether the distribution of quality bits indicate the units are below a threshold level of correctness, and by comparing characteristics of that distribution to a given set of characteristics predetermined to be prone to result in incorrect decoding. Among the symbols produced for block decoding, symbols containing one or more bits that correspond to units that were in subsequences detected to be prone to erroneous soft-decision convolution decoding are flagged or tagged, and thereby, errors in the stream of symbols may be soft-decision block decoded by erasing the flagged symbols. |
