| abstract |
A system and method for decoding blocks and concatenated codes are provided. Such systems and methods include improved iterative decoding techniques based on belief propagation algorithms that have particular advantages when applied to codes with higher density parity check matrices. During the iterations of the reliability spreading, variable-to-check messages can be computed. According to some embodiments, a scaling factor may be computed based on the smallest absolute values in the set of variable-to-check messages and may be used to scale the messages that were passed during the reliability spread . According to other embodiments, the positive or negative signs of the variable-to-check messages can be compared and used to generate a modified variable-to-check message. In accordance with other embodiments, sparse parity check matrices may be used to provide an updated log-likelihood ratio with soft-input soft-output message passing. ). ≪ / RTI > These and other improvements improve the decoding of H / M / LDPC codes including Reed-Solomon codes that can be used in HD radio systems. |