Mixed-Rate Codeword Interleaving for Trellis Detection Reliability
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Solution Overview
Problem
Current data storage devices face challenges in accurately positioning the head over servo tracks due to limitations in trellis sequence detection, particularly in noisy environments, where existing encoding and interleaving methods do not effectively improve decoding reliability and sector failure rates.
Innovation Solution
The implementation of mixed-rate codewords with different code rates and sizes, where a lower rate codeword is interleaved with a higher rate codeword to enhance decoding accuracy, using non-uniform and uniform interleaving techniques to generate an interleaved codeword that improves trellis detector performance by increasing redundancy and reliability metrics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional single-rate codeword encoding is used, then the device complexity is low, but the decoding reliability and sector success rate deteriorate in noisy environments
Solution Approach 1:
The encoding process is segmented into two distinct stages: first encoding data with a lower rate code to generate initial reliability metrics, then encoding with a higher rate code to generate final codewords. This segmentation allows each encoding stage to specialize in different aspects of error protection, improving overall decoding reliability while managing complexity through modular processing
Solution Approach 2:
The lower rate encoding is performed as a preliminary action before the higher rate encoding. This preliminary encoding establishes initial reliability metrics that guide the subsequent higher rate decoding process, particularly in pruning the trellis search space during Viterbi detection, thereby improving final decoding reliability
2Reliability
If mixed-rate codewords with interleaving are implemented, then the sector failure rate is reduced, but the processing time and computational load increase
Solution Approach 1:
The codeword structure is segmented into portions derived from different rate encodings, with interleaving distributing these segments across the codeword. This allows the decoder to process different segments with appropriate decoding strategies, reducing overall processing time while maintaining high sector success rates through targeted error correction
Solution Approach 2:
The lower rate encoding serves as a preliminary filtering stage that quickly identifies and corrects obvious errors before the more computationally intensive higher rate decoding. This preliminary action reduces the computational burden on the main decoding process, decreasing overall processing time
3Reliability
If lower rate codeword encoding is used, then the redundancy and reliability metrics are improved, but the data storage capacity is reduced
Solution Approach 1:
The data stream is segmented and encoded at different rates: some portions receive stronger protection through lower rate encoding while other portions use higher rate encoding. This segmentation allows the system to optimize reliability metrics for critical data portions while maintaining overall storage capacity through mixed-rate encoding
Solution Approach 2:
Different portions of the data receive different levels of encoding protection based on their importance and error susceptibility. The lower rate encoding provides higher redundancy locally for portions requiring greater reliability, while higher rate encoding is used for portions where capacity is more critical, achieving local optimization of the reliability-capacity tradeoff
Data Source
AI summary
A data storage device is disclosed comprising a storage medium. Input data is encoded according to at least one channel code constraint to generate first data and second data. The first data is encoded into a first codeword, and the second data is encoded into a second codeword, wherein a first code rate of the first codeword is less than a second code rate of the second codeword. The first codeword and the second codeword are interleaved to generate an interleaved codeword, and the interleaved codeword is written to the storage medium.