Stuck Bit Coding With Codeword Masks for Low Redundancy
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Solution Overview
Problem
Non-volatile storage devices face issues with stuck bit errors, where bits become permanently stuck at a value and current methods to handle these errors increase the rate of miscorrection during decoding.
Innovation Solution
A method is introduced that generates a set of masks, which are codewords, to mask stuck bits, using full or shortened codewords, and stores label bits to minimize redundancy and maintain low miscorrection rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extra bits are stored for side information to handle stuck bits, then stuck bit errors can be corrected, but storage redundancy increases
Solution Approach 1:
The patent extracts only the essential side information (stuck bit positions and values) from the full error correction data, storing only what is necessary to correct stuck bit errors rather than complete error correction codes. This reduces storage redundancy while maintaining the ability to correct stuck bit errors.
Solution Approach 2:
The patent changes the approach from storing complete error correction codes to storing parameter-based side information (positions and values of stuck bits). This parameter-based representation significantly reduces the quantity of data that needs to be stored while preserving the error correction capability.
2Reliability
If decoding masks that are not codewords are used to correct stuck bits, then stuck bit errors can be corrected, but the rate of miscorrection increases
Solution Approach 1:
The patent converts the potentially harmful effect of using non-codeword masks into a beneficial process by systematically generating decoding masks from codewords and their sums. This structured approach ensures that even when masks are applied to correct stuck bits, the miscorrection rate remains controlled and acceptable.
Solution Approach 2:
The patent performs preliminary generation and validation of decoding masks before actual decoding operations. By pre-establishing a set of valid decoding masks derived from codewords, the system ensures that mask application during decoding will not unduly increase miscorrection rates.
3Ease of operation
If label bits are stored with messages to identify decoding masks, then appropriate masks can be selected, but message overhead increases
Solution Approach 1:
The patent makes the encoding mask serve multiple functions: it acts as both the error correction code and the decoding mask identifier. By designing the encoding mask to have specific properties (being a codeword or sum of codewords), it automatically serves as a valid decoding mask, eliminating the need for separate label bits and reducing message overhead.
Solution Approach 2:
The patent merges the function of error correction codes with the function of decoding mask identifiers. The encoding mask is designed to simultaneously perform error correction and serve as the basis for identifying appropriate decoding masks, thereby combining multiple functions into a single structure and reducing overall overhead.
Data Source
AI summary
A storage device minimizes redundancy for stuck bit codes when writing a message to a memory device. A controller generates a set of masks that are codewords and that include values that correspond to stuck bit values. The set of masks may include full length codewords or shortened codewords. When the controller receives a message including a predefined number of label bits and determines that a location in the memory device where the message is be stored includes two stuck bits, the controller encodes the message to produce a first message codeword. The controller then locates a mask from the set of masks, wherein when the mask is added to the first message codeword, any two stuck message bits are masked. The controller computes a final message codeword using the first message codeword and the mask and stores the final message codeword on the memory device.