Decoding method and apparatus

A method of decoding, comprising:

• identifying bits among first bits, according to correctness levels of the first bits;
• decoding the first bits into second bits;
• and
• decoding the second bits in accordance with the identified bits of the first bits.

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 FEC decoding, comprising:

• identifying sequences of FEC encoded first bits, the sequences having a number of bits that have a low intrinsic quality level, and the sequences being identified based on such number;
• Viterbi decoding the FEC encoded first bits and the identified sequences into second bits;
• and
• erasure block decoding the second bits by erasing certain bits of the second bits, or symbols that contain the certain bits, where the certain bits correspond to bits in the identified sequences of first bits.

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.

A decoding apparatus, comprising:

• a detector detecting a portion of data with a probability of being erroneously decoded by a convolutional decoder;
• a convolutional decoder convolutionally decoding the data;
• and
• a block decoder further decoding the data by taking into account that the data has a portion that has been detected to have a probability of being erroneously decoding by said convolutional decoder;
• wherein the further decoding of said block decoder is performed by block decoding with erasure of data corresponding to the detected portions.