Log-likelihood-ratio (llr) generation algorithm for low-density-parity-check (ldpc) codes used in flash memory
AssigneeGoke US Research Laboratory
InventorChandra Varanasi
Life of this patent
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Abstract
Apparatuses and methods suitably configured to utilize at least one algorithm for generating log-likelihood-ratio (LLR) values for low-density-parity-check (LDPC) codes used in flash memory-based systems. Additionally, at least one algorithm sets soft-read thresholds in the memory in such a way as to maximize the mutual information (MI) of the channel created by those thresholds for preventing errors.
Claims20
A system for generating log-likelihood-ratio (LLR) values for low-density-parity-check (LDPC) codes stored on a memory, comprising;
- a low-density-parity-check (LDPC) encoder communicatively coupled to the memory, the memory having a plurality of cells each configured to store at least one data bit;
- a LDPC decoder communicatively coupled to the memory;
- a controller having control circuitry communicatively coupled to the LDPC decoder, the controller configured to:
- generate binary data in the plurality of the cells;
- write the binary data in the plurality of cells;
- determine hard-decisions based on a predefined hard-read voltage threshold for each of the plurality of cells;
- generate soft-read threshold settings;
- determine probabilities corresponding to each soft-read threshold setting;
- determine mutual information (MI) for the set of probabilities generated by the soft-read threshold settings;
- determine the soft-read thresholds that resulted in maximum mutual information (MI);
- and
- generate log-likelihood-ratio (LLR) values for the LDPC for the set of soft-read thresholds that maximized the mutual information (MI).
An apparatus comprising;
- a memory device having a plurality of cells each configured to store at least one bit;
- a LDPC encoder communicatively coupled to the memory device;
- a LDPC decoder communicatively coupled to the memory device;
- a controller having control circuitry communicatively coupled to a LDPC decoder, the controller configured to:
- generate binary data in the plurality of the cells;
- write the binary data in the plurality of cells;
- generate soft-read threshold settings;
- determine probabilities corresponding to each soft-read threshold setting;
- determine mutual information (MI) for the set of probabilities generated by the soft-read threshold settings;
- determine the soft-read thresholds that resulted in maximum mutual information (MI);
- and
- generate log-likelihood-ratio (LLR) values for the LDPC for the set of soft-read thresholds that maximized the mutual information (MI).
A method for generating log-likelihood-ratio (LLR) values for low-density-parity-check (LDPC) codes stored in memory, the method comprising the steps of:
- generating binary data in a plurality of cells stored in the memory;
- writing the binary data in the plurality of cells;
- determining hard-decisions based on a predefined hard-read voltage threshold for each of the plurality of cells;
- generating soft-read threshold settings;
- determining probabilities corresponding to each soft-read threshold setting;
- determining mutual information (MI) for the set of probabilities generated by the soft-read threshold settings;
- determining the soft-read thresholds that resulted in maximum mutual (MI) information;
- and
- generating log-likelihood-ratio (LLR) values for the LDPC for the set of soft-read thresholds that maximized the mutual information (MI).
Dependencies are inferred from the claim text.