Charge Constrained Codes for NAND Flash Error Correction
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Solution Overview
Problem
Solid state storage systems, such as NAND Flash systems, face issues with error correction decoding efficiency due to high noise levels in read data, leading to reduced throughput and increased power consumption.
Innovation Solution
The implementation of charge constrained codes, which enforce rules on bit sequences to ensure error correction encoding can be performed independently and systematically, allowing for faster and more power-efficient processing by using Boolean operations instead of traditional error correction encoders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional error correction encoding is used on noisy read data, then error correction capability is maintained, but decoding time increases and throughput drops
Solution Approach 1:
The patent applies charge constrained coding during the write operation to pre-condition the data, ensuring that the encoded data has bounded charge transitions. This preliminary encoding structure enables the decoder to quickly validate data integrity without extensive processing, resolving the contradiction by preparing the data in advance to minimize later decoding overhead.
Solution Approach 2:
The patent transforms the encoding approach by changing from traditional error correction codes to charge constrained codes with specific electrical charge properties. This parameter change in the encoding method allows for faster validation while maintaining error detection capability, thus improving throughput without sacrificing reliability.
2Reliability
If traditional error correction encoding is used on noisy read data, then error correction capability is maintained, but power consumption increases
Solution Approach 1:
By applying charge constrained coding during writing, the system pre-structures the data to enable rapid validation during reading. This preliminary encoding reduces the computational effort required during read operations, thereby reducing power consumption while maintaining error correction capability.
Solution Approach 2:
The patent replaces complex traditional error correction encoding mechanisms with a simpler charge constrained coding system that relies on electrical charge properties rather than extensive computational processing. This substitution reduces the mechanical/computational overhead and associated power consumption during error correction operations.
3Measurement precision
If extensive error correction processing is performed, then decoding accuracy is improved, but processing time increases
Solution Approach 1:
The patent changes the encoding parameters to use charge constrained codes with specific transition bounds, which inherently provide error detection capabilities. This parameter change allows for accurate decoding with minimal processing time, as the charge constraints enable quick validation without extensive computational analysis.
Data Source
AI summary
A charge constrained bit sequence is processed to obtain a lower bound on a number of bit errors associated with the charge constrained bit sequence. The lower bound is compared against an error correction capability threshold associated with an error correction decoder. In the event the lower bound is greater than or equal to the error correction decoder threshold, an error correction decoding failure is predicted.