| 摘要 |
An LDPC encoding system produces an encoded block by encoding the data as i data sub-blocks using an LDPC code H1, XOR'ing the H1 sub-block code words to generate a block code word and further encoding the block code word using an LDPC code H2 to produce p parity bits. The encoded block consists of a concatenation of the H1 code words and the p parity bits. To decode the encoded block, the system decodes each H1 sub-block code word and, if all of the H1 sub-block code words converge, the block has been successfully decoded. Otherwise, if one of the H1 code words fails to converge, the system performs an "extended" decoding operation in which the system produces a vector C by XOR'ing the i-1 properly decoded H1 sub-block code words. The system then combines the vector C with the sign values of the failed H1 sub-block code word, appends the parity bits and decodes the result as an H2 code word over the H2 LDPC code. For a next iteration, the system removes the vector C from the non-parity sign bits of the decoded H2 code word and provides the results along with the associated reliability information to an ISI detector for further decoding to produce an updated failed H1 code word. The updated H1 sub-block code word is then iteratively decoded as part of an H2 code word, and so forth, by combing and removing the vector C.
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