Adaptive LLR Estimation for Soft Decoding in Non-Volatile Memory
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Solution Overview
Problem
Conventional pre-defined LLR tables fail to provide accurate LLR values for time-varying non-volatile storage devices, leading to suboptimal error correction performance in soft decoding.
Innovation Solution
A method and system for adaptively estimating LLR values by reading data from non-volatile storage devices using soft read reference voltages, decoding the data, and calculating LLR based on the ratio of ones to zeros in each zone delineated by the reference voltages, allowing for dynamic adjustment of LLR values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pre-defined LLR table is used to provide LLR values for decoding, then the device complexity is reduced and ease of operation is improved, but the measurement precision of LLR values deteriorates because the pre-defined table cannot provide accurate LLR values for time-varying non-volatile storage devices
Solution Approach 1:
The system uses the decoding results from the soft decoding process itself to generate LLR values. The decoder's output (number of ones and zeros in each zone) is fed back to calculate LLR values, making the system self-sufficient and eliminating the need for external pre-defined tables or complex calibration procedures
Solution Approach 2:
The soft decoding process provides feedback information (decoding results showing number of ones and zeros) that is used to dynamically adjust and calculate LLR values. This feedback loop enables the system to adapt to time-varying storage conditions while maintaining accurate LLR estimation
2Reliability
If a pre-defined LLR table is used, then the processing time is reduced and productivity is improved, but the reliability of error correction deteriorates due to inaccurate LLR values for time-varying devices
Solution Approach 1:
The system performs soft decoding first to obtain decoding results, which are then used to calculate LLR values before the actual error correction process. This preliminary action ensures that accurate, adaptive LLR values are ready when needed for error correction, improving reliability without significant time penalty
Solution Approach 2:
The LLR estimation process is merged with the soft decoding process. Instead of separate LLR table lookup or calibration steps, the system combines decoding and LLR estimation into a single integrated workflow, where decoding results directly inform LLR calculation, reducing total processing time while maintaining accuracy
Data Source
AI summary
Systems and methods are provided for estimating LLR values used for soft decoding of data stored in non-volatile storage devices. A method may include reading data stored in a non-volatile storage device using a group of soft read reference voltages, decoding the data read from the non-volatile storage device in a soft decoding process, obtaining a number of ones and a number of zeros for each zone of a plurality of zones delineated by the group of soft read reference voltages and obtaining a log-likelihood ratios (LLR) for each zone of the plurality of zones based on a ratio of the number of ones to the number of zeros in each zone.