| 摘要 |
A decoder for iterative decoding of parallel concatenated Zigzag codes (PCZZ) includes circuitry for utilizing all extrinsic information during iterative decoding by updating likelihood information for parity bits LPi, i=1,..., M during iterations. The extrinsic information for the parity bits is included in iterations by re-calculating soft values for parity bits LPi<(k)> for each iteration k. In one embodiment the parity bit soft values are re-calculated in a plurality of circuit blocks following Max-Log-APP (MLA) decoder blocks, based on soft values for data bits LDi<(k)>. In another embodiment the parity bit soft values are re-calculated recursively within the plurality of MLA decoders. The decoder operates to control the convergence of the decoder by monitoring a soft value of one parity check symbol, e.g., L<(k-1)>Äp(IM)Ü, where p(IM) represents the last parity check bit in an I X M parity check array. A decoder iteration stopping rule may be implemented by testing a likelihood measure associated with a last parity check symbol in a parity check column. In one case the likelihood measure may be given by L<(k-1)>Äp(IM)Ü > threshold, and in another case the likelihood measure may be given by L<(k-1)>Äp(I)Ü > threshold. The likelihood measure is given in general by: L<(k-1)>Äp(I)Ü > threshold, L<(k-1)>Äp(2I)Ü > threshold,..., L<(k-1)>Äp(IM)Ü > threshold, where the value of the threshold is a function of data block size. <IMAGE>
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