Reverse-Indexed ECC Mapping for Flash Memory Read Errors
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Solution Overview
Problem
Data storage devices using flash memory, such as NAND, are prone to read errors, and existing error correcting codes may fail to correct errors effectively, necessitating improved error correcting mechanisms.
Innovation Solution
Implementing an error control coding (ECC) unit that splits data into chunks and arranges each chunk into multiple codewords, using a reverse indexing mapping scheme to reduce hardware complexity and improve error correction capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is protected by traditional error correcting codes in flash memory, then read errors can be corrected, but the hardware complexity and mapping complexity increase
Solution Approach 1:
The patent divides data into multiple data chunks, where each chunk is arranged as part of at least two different codewords. This segmentation allows the system to distribute data across multiple codewords, reducing the mapping complexity from O(N^2) to O(1) for syndrome updating and O(N) for data updating, while maintaining error correction capability.
Solution Approach 2:
The patent employs reverse indexing to map codewords back to data chunks. Instead of traditional forward mapping, the system uses reverse indexing where each codeword contains metadata indicating which data chunks it represents. This inversion of the mapping approach significantly reduces hardware complexity while preserving error correction functionality.
2Reliability
If each data chunk is arranged as part of multiple codewords, then error correction performance improves, but the device complexity increases
Solution Approach 1:
The patent creates a universal mapping structure where each codeword serves multiple functions: it contains actual data, metadata about other data chunks it represents, and enables both syndrome updating and data retrieval. This multi-functionality allows the same codeword structure to handle multiple error correction operations without requiring separate complex mapping mechanisms.
Solution Approach 2:
The system creates simplified copies of mapping information within each codeword through reverse indexing. Instead of maintaining complex external mapping tables, each codeword contains embedded metadata that acts as a simplified copy of the mapping relationship, reducing the need for complex external mapping hardware while maintaining error correction capability.
Data Source
AI summary
Memory systems and operating methods thereof comprise a memory storage and an error control coding (ECC) unit. The memory storage stores data which is split into a plurality of data chunks. The error control coding (ECC) unit is suitable for arranging each data chunk into codewords, each data chunk is arranged as part of at least two codewords, and mapping the codewords by reverse indexing the data chunks.