Parity Sector LDPC Decoding for Un-Converged Storage Codewords
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Solution Overview
Problem
Prior art data storage devices face inefficiencies in error correction during read operations, particularly when updating reliability metrics of un-converged codewords, as Viterbi-type detector updates can increase signal noise, whereas parity sector updates more effectively compensate for signal noise sources.
Innovation Solution
Emphasizing the use of parity sectors over Viterbi-type detectors for updating reliability metrics, with iterative processing using Low Density Parity Check (LDPC) decoders and Viterbi-type detectors, and employing multiple parity sectors for improved convergence and error correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Viterbi-type detector is used to update reliability metrics of un-converged codewords, then error correction processing is performed, but signal noise increases
Solution Approach 1:
The patent applies different update strategies to different codewords based on their convergence status. Converged codewords use Viterbi-type detector updates, while un-converged codewords use parity sector updates. This localized differentiation resolves the contradiction by applying the appropriate method to each codeword's specific state, avoiding noise increase for un-converged codewords while maintaining error correction capability.
Solution Approach 2:
The patent implements dynamic switching between Viterbi-type detector updates and parity sector updates based on the convergence status of each codeword. The system adapts its processing strategy in real-time during iterative decoding, transitioning from Viterbi updates when convergence is detected to parity sector updates when un-converged, thereby resolving the noise versus reliability contradiction dynamically.
2Reliability
If multiple iterations are performed with Viterbi-type detector and LDPC decoder, then convergence is improved, but processing time increases
Solution Approach 1:
The patent performs partial iterations using only the parity sector for un-converged codewords instead of full Viterbi-LDPC iteration cycles. By applying a reduced update strategy (parity sector only) to un-converged codewords, the system achieves convergence improvement without the full time cost of repeated Viterbi-type detector updates, thus resolving the time versus convergence contradiction.
Solution Approach 2:
The patent segments the error correction processing into two distinct paths: one for converged codewords (continuing full Viterbi-LDPC iterations) and one for un-converged codewords (using parity sector updates). This segmentation allows the system to optimize processing time for un-converged codewords while maintaining convergence efforts, resolving the time-convergence tradeoff.
3Reliability
If parity sector updates are emphasized for un-converged codewords, then signal noise is reduced and convergence is improved, but device complexity increases
Solution Approach 1:
The patent uses the parity sector, which is already generated and stored as part of the original codeword structure, to update un-converged codewords. This self-service approach leverages existing data (the parity information) to improve convergence without requiring additional hardware complexity or external resources, thus resolving the complexity versus accuracy contradiction.
Solution Approach 2:
The patent changes the update parameter from Viterbi-type detector outputs to parity sector values for un-converged codewords. This parameter substitution uses the pre-computed parity information to replace the noisy Viterbi updates, improving convergence accuracy while avoiding the complexity of modifying the underlying decoding architecture.
Data Source
AI summary
A data storage device is disclosed comprising a non-volatile storage medium (NVSM), wherein a plurality of codewords and corresponding parity sector are written to the NVSM and then read from the NVSM. Each codeword read from the NVSM is processed using a Viterbi-type detector, thereby generating codeword reliability metrics. The codeword reliability metrics for at least some of the codewords are processed using a low density parity check (LDPC) type decoder, thereby generating a LDPC reliability metric for each symbol of at least one codeword. The LDPC reliability metrics for at least one of an un-converged codeword are processed using the parity sector, thereby updating the un-converged codeword reliability metrics. Processing the codeword reliability metrics with the LDPC decoder and updating the reliability metrics with the parity sector is repeated at least once before updating the LDPC reliability metrics of at least the un-converged codeword using the Viterbi-type detector.