A bit interleaving method applying a bit permutation process to a QC LDPC codeword made up of N cyclic blocks of Q bits each, dividing the processed codeword into constellation words of M bits each, and applying an intra-cyclic-block permutation process to the cyclic blocks, where the codeword is divided into FN/M folding sections of M/F cyclic blocks each and the constellation words are each associated with one of the folding sections, and the bit permutation process is applied such that the constellation words are each made up of F bits from each of M/F different cyclic blocks in the associated section, after the permutation process.

A bit interleaving method applying a bit permutation process to a QC LDPC codeword made up of N cyclic blocks of Q bits each, dividing the processed codeword into constellation words of M bits each, and applying an intra-cyclic-block permutation process to the cyclic blocks, where the codeword is divided into FN/M folding sections of M/F cyclic blocks each and the constellation words are each associated with one of the folding sections, and the bit permutation process is applied such that the constellation words are each made up of F bits from each of M/F different cyclic blocks in the associated section, after the permutation process.

The invention relates to a method, a non-transitory computer-readable storage medium and an apparatus for decoding a Low-Density Parity-Check (LDPC) code. The method, which is performed by a processing unit in an LDPC decoder, includes the following steps: determining whether a bit flipping algorithm when decoding a codeword enters a trapping state after an observation period during which a sequential selection strategy is used; and modifying a scheduling strategy to a non-sequential selection strategy and performing the bit flipping algorithm on the codeword under the non-sequential selection strategy when the bit flipping algorithm enters the trapping state. The codeword is divided into chunks in fixed-length and the sequential selection strategy indicates sequentially selecting the chunks in the codeword, so that the bit flipping algorithm is performed on one selected chunk only each time. The non-sequential selection strategy indicates an arbitrary selection combination of the chunks in the codeword, which is different from that under the sequential selection strategy.

Post-processing circuitry for LDPC decoding includes check node processor for processing shifted LLR values, a hard decision decoder circuitry for receiving processed LLR information and performing parity checks on the processed LLR information. Post-processing control circuitry controls updating of LLR information in the check node processor. The check node processor, hard decision decoder, and control circuitry cooperate to identify check nodes with unsatisfied parity checks after an iteration cycle, identify neighborhood variable nodes that are connected with unsatisfied check nodes, identify satisfied check nodes which are connected to neighborhood variable nodes, and modify messages from neighborhood variable nodes to satisfied check nodes if needed to introduce perturbations to resolve decoding errors. Neighborhood identification circuitry determines which variable nodes are connected with unsatisfied check nodes, that have failed a parity check, and produces a signal indicating which variable nodes are connected to unsatisfied check nodes.

A decoder performs forward error correction based on quasi-cyclic regular column-partition low density parity check codes. A method for designing the parity check matrix reduces the number of short-cycles of the matrix to increase performance. An adaptive quantization post-processing technique further improves performance by eliminating error floors associated with the decoding. A parallel decoder architecture performs iterative decoding using a parallel pipelined architecture.

A low-density parity-check decoder utilizes information about hard errors in a storage medium to identify bit locations to flip log-likelihood ratios while attempting to decode codewords. The decoder iteratively flips and saturates log-likelihood ratios for bits at hard error locations and re-decodes until a valid codeword is produced. The decoder also identifies variable nodes associated with trapping sets for iterative log-likelihood ratio bit flipping.

A bit interleaving method applying a bit permutation process to a QC LDPC codeword made up of N cyclic blocks of Q bits each, dividing the processed codeword into constellation words of M bits each, and applying an intra-cyclic-block permutation process to the cyclic blocks, where the codeword is divided into FN/M folding sections of M/F cyclic blocks each and the constellation words are each associated with one of the folding sections, and the bit permutation process is applied such that the constellation words are each made up of F bits from each of M/F different cyclic blocks in the associated section, after the permutation process.

A method and apparatus as described herein provide a novel modification to any iterative FEC decoder method that can improve FER performance in the error floor region. Many iterative FEC methods, such as commonly used LDPC decoders, have error floors where the performance of the decoder does not improve below a certain threshold. Error Floors are caused by trapping sets from which traditional methods cannot escape. With Stochastic Floor Mitigation, according to embodiments of the present disclosure, noise is strategically added to the operations occurring during decoding resulting in significantly improved error floor performance.

Systems and method relating generally to data processing, and more particularly to systems and methods for accessing a data set from a solid state storage device, using a data decoding circuit to apply a data decoding algorithm to the data set to yield a decoded output, where the decoded output includes at least one error, identifying at least one critical location in the data set, and estimating a voltage associated with the data in the data set corresponding to the critical location.