Method for decoding data in non-volatile storage using reliability metrics based on multiple reads
First Claim
1. A method for decoding data in non-volatile storage, comprising:
- performing a first sense operation on at least one non-volatile storage element;
providing a first code word based on the first sense operation;
performing a decoding process for the first code word using a first set of reliability metrics which is based on the first code word; and
if the decoding process does not meet a first condition, the first condition comprises the decoding process converging within a given time period, performing a second sense operation on the at least one non-volatile storage element and continuing the decoding process based on the second sense operation.
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Abstract
Data stored in non-volatile storage is decoded using iterative probabilistic decoding and multiple read operations to achieve greater reliability. An error correcting code such as a low density parity check code may be used. In one approach, initial reliability metrics, such as logarithmic likelihood ratios, are used in decoding read data of a set of non-volatile storage element. The decoding attempts to converge by adjusting the reliability metrics for bits in code words which represent the sensed state. If convergence does not occur, e.g., within a set time period, the state of the non-volatile storage element is sensed again, current values of the reliability metrics in the decoder are adjusted, and the decoding again attempts to converge.
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Citations
19 Claims
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1. A method for decoding data in non-volatile storage, comprising:
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performing a first sense operation on at least one non-volatile storage element; providing a first code word based on the first sense operation; performing a decoding process for the first code word using a first set of reliability metrics which is based on the first code word; and if the decoding process does not meet a first condition, the first condition comprises the decoding process converging within a given time period, performing a second sense operation on the at least one non-volatile storage element and continuing the decoding process based on the second sense operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A non-volatile storage system, comprising:
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a set of non-volatile storage elements; and one or more control circuits in communication with the set of non-volatile storage elements, the one or more control circuits perform a first sense operation on at least one non-volatile storage element of the set, provide a first code word based on the first sense operation, perform a decoding process for the first code word using a first set of reliability metrics which is based on the first code word, and if the decoding process does not meet a first condition, perform a second sense operation on the at least one non-volatile storage element and continue the decoding process based on the second sense operation, wherein the first code word comprises bits which indicate whether a voltage threshold of the at least one non-volatile storage element is above or below each of a plurality of different voltage threshold levels, as indicated by the first sense operation. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method for decoding data in non-volatile storage, comprising:
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performing a first sense operation on at least one non-volatile storage element; providing a first code word based on the first sense operation; performing a decoding process for the first code word using a first set of reliability metrics which is based on the first code word, the first code word comprises multiple bits in respective bit positions, and the first set of reliability metrics includes reliability metrics for each bit; and if the decoding process does not meet a first condition, performing a second sense operation on the at least one non-volatile storage element and continuing the decoding process based on the second sense operation, the continuing the decoding process based on the second sense operation comprises, for at least one of the bit positions of the first code word, adjusting the reliability metric to indicate a higher reliability when a sensed programming state of the first sense operation is consistent with a sensed programming state of the second sense operation. - View Dependent Claims (18, 19)
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Specification