Decoding method

A method of decoding, comprising:

• decoding first bits into second bits;
• identifying bits, among the first bits, having a probability of erroneous decoding by said first decoding, said identifying being based on correctness levels of the first bits, and being performed separate from said decoding of the first bits;
• flagging bits of the second bits that correspond to identified bits among the first bits;
• and decoding the second bits after said flagging.

A method of decoding forward error correction (FEC) encoded data, comprising:

• receiving a stream of units of FEC encoded bits that are derived from a transmitted signal, where each unit represents a one-bit data value, and each unit comprises correctness bits together reflecting a level of probability that the one-bit data value represented by the unit differs from a corresponding one-bit value in the signal before it was transmitted;
• correcting errors in the stream of units of FEC encoded bits by using the correctness bits to perform soft-decision convolution decoding on the stream of units of FEC bits, where the soft-decision convolution decoding produces a stream of symbols for block decoding, the symbols comprising bits;
• identifying, in the stream of units of FEC bits, subsequences of units that are prone to erroneous soft-decision convolution decoding, by determining, for the sub-sequences, a total number of units whose correctness bits indicate the units are below a threshold level of correctness, and by comparing the total number to a given number that is based on or equal to a total number of units in the subsequences;
• flagging for erasure symbols among the produced symbols, the flagged symbols comprising one or more bits that correspond to units that were in subsequences identified to be prone to erroneous soft-decision convolution decoding;
• and correcting errors in the stream of symbols by block decoding codewords comprised of symbols including symbols not tagged for erasure.