Use of a $d$-Constraint During LDPC Decoding in a Bliss Scheme
Abstract
Bliss schemes of a run length limited (RLL) codec in combination with an LDPC codec, generate LDPC parity bits over a systematic sequence of RLL channel bits that are inherently redundant as they satisfy e.g. a minimum run length constraint. That is the subsequences consisting of runs of length , viz. and , cannot occur. We propose to use this redundancy during LDPC decoding in a Bliss scheme by introducing additional -constraint nodes in the factor graph used by the LDPC decoder. The messages sent from these new nodes to the variable or codeword bit nodes exert a ``force'' on the resulting soft-bit vector coming out of the LDPC decoding that give it a tendency to comply with the -constraints. This way, we can significantly reduce the probability of decoding error.
Cite
@article{arxiv.0707.3925,
title = {Use of a $d$-Constraint During LDPC Decoding in a Bliss Scheme},
author = {Andries P. Hekstra},
journal= {arXiv preprint arXiv:0707.3925},
year = {2007}
}