Partial Reverse Concatenation for Tighter Modulation Constraints
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Solution Overview
Problem
Conventional reverse concatenation schemes for data storage face challenges such as high implementation complexity, weakening of modulation constraints, and inability to satisfy non-uniform constraints, which hinder their practical application in data storage systems like magnetic tape drives and optical storage systems.
Innovation Solution
The implementation of a partial reverse concatenated modulation code, where modulation coding (MC) is performed subsequent to C2 error correction coding (ECC) but prior to C1 encoding, simplifying the data flow architecture and allowing tighter modulation constraints to be satisfied without inserting C2 symbols into the MC-encoded data stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional reverse concatenation is used to achieve high code rate and improve format efficiency, then modulation code rate improves, but implementation complexity increases significantly
Solution Approach 1:
The patent applies reverse concatenation by inverting the conventional encoding order: instead of encoding data first and then modulation encoding, the patent performs modulation encoding first and then error correction encoding. This inversion achieves higher code rates (0.9951 vs 0.9697) and improved format efficiency while managing implementation complexity through systematic redesign of the data flow architecture.
Solution Approach 2:
The patent segments the encoding process into distinct stages: modulation encoding stage, error correction encoding stage, and symbol insertion stage. By dividing the complex reverse concatenation process into manageable segments with clear interfaces, the implementation complexity is reduced while maintaining the benefits of high code rate and format efficiency.
2Productivity
If C2 symbol insertion is performed after modulation coding to achieve reverse concatenation, then code rate improves, but modulation constraints are weakened
Solution Approach 1:
The patent performs modulation encoding as a preliminary action before error correction encoding and symbol insertion. By establishing the modulation constraints early in the process and maintaining them throughout subsequent operations, the patent avoids weakening of constraints while still achieving the desired code rate improvement through reverse concatenation.
Solution Approach 2:
The patent applies different encoding operations to different parts of the data stream at appropriate stages: modulation encoding is applied to the entire data stream first to establish constraints, then error correction encoding is applied to specific portions, and symbol insertion is performed locally where needed. This localized approach maintains modulation constraints while achieving high code rate.
3Productivity
If complete reverse concatenation architecture is implemented to achieve high code rate, then format efficiency improves, but backward compatibility becomes difficult to maintain
Solution Approach 1:
The patent implements partial reverse concatenation rather than complete reversal of all encoding operations. By selectively applying reverse concatenation to specific parts of the data flow while maintaining conventional encoding for other parts, the patent achieves improved format efficiency while preserving backward compatibility with existing systems that expect conventional encoding formats.
Data Source
AI summary
In one embodiment, a data storage system includes a write channel for writing data to a storage medium, the write channel configured to utilize a partial reverse concatenated modulation code. The write channel includes logic adapted for encoding data sets using a C2 encoding scheme, logic adapted for adding a header to each subunit of the data sets, logic adapted for encoding the headers of the data sets with a first modulation encoding scheme, logic adapted for encoding data portions of the data sets with a second modulation encoding scheme, logic adapted for encoding portions of the one or more C2-encoded data sets using a C1 encoding scheme, logic adapted for combining the C1-encoded portions with the modulation-encoded headers of the C2-encoded data sets using a multiplexer, and logic adapted for writing the one or more combined C1 - and C2-encoded data sets to data tracks.