Rank Modulation Decoder Using Soft and Hard Bit Inputs
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Solution Overview
Problem
Existing rank modulation decoders face challenges in achieving effective error correction in multi-level-cell (MLC) memory systems due to variations in sensed programming states, which can lead to data errors.
Innovation Solution
The use of both soft bits and hard bits as inputs to a rank modulation decoder enhances error correction capability by providing additional reliability information, allowing for more accurate and efficient decoding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only hard bits are used as input to the rank modulation decoder, then the device complexity is reduced, but the error correction capability deteriorates
Solution Approach 1:
The input data is segmented into two distinct types: hard bits (definitive 0 or 1 values) and soft bits (reliability indicators). This segmentation allows the decoder to process different types of information separately, using hard bits for definitive decisions and soft bits for probabilistic error correction, thereby improving error correction capability without requiring a complete redesign of the decoder architecture.
Solution Approach 2:
The system changes the parameter of input data from purely definitive hard bits to a combination of hard bits and soft bits with reliability information. This parameter change enables the decoder to weigh different inputs differently, improving error correction by allowing probabilistic reasoning about the likelihood of bit errors based on the reliability indicators provided by soft bits.
2Measurement precision
If soft bits are used to provide reliability information, then error correction accuracy is improved, but the processing time increases
Solution Approach 1:
Reliability information is prepared in advance during the sensing phase, where soft bits are generated alongside hard bits before the decoding process begins. This preliminary action ensures that when the decoder receives the data, the reliability information is already available, eliminating the need for additional processing steps during decoding and thus avoiding increased latency.
Solution Approach 2:
The sensing circuit automatically generates both hard bits and soft bits during the normal read operation, making the reliability information available without requiring separate measurement or processing steps. The system serves its own error correction needs by producing the necessary reliability data as a byproduct of the standard sensing process, thereby improving accuracy without adding time overhead.
Data Source
AI summary
A method includes providing data including hard bit data and soft bit data to a rank modulation decoder.