Adaptive LLR based on syndrome weight

• US 9,009,576 B1
• Filed: 03/15/2013
• Issued: 04/14/2015
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Enterprise IP LLC (Western Digital Corporation)
• Inventors: Jeon, Seungjune, Zhu, Jiangli, Tai, Ying, Chen, Xiaoheng
• Primary Examiner(s): TU, CHRISTINE TRINH LE
• Application Number:
  US13/831,713
• Time in Patent Office: 760 Days
• Field of Search: 714/780, 714/785, 714/773, 714/758, 714/799, 714/817, 714751-752, 714/755
• US Class Current: 714/780
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• CPC Class Codes: H03M 13/1108 Hard decision decoding, e.g. bit flipping, modified or weighted bit flipping
• CPC Class Codes: H03M 13/1111 Soft-decision decoding, e.g. by means of message passing or belief propagation algorithms
• CPC Class Codes: H03M 13/3715 Adaptation to the number of estimated errors or to the channel state
• CPC Class Codes: H03M 13/45 Soft decoding, i.e. using symbol reliability information H03M13/41 takes precedence

Abstract

Systems, methods and/or devices that enhance the reliability with which data can be stored in and read from a memory utilize an error indicator to adaptively determine the soft information values used for decoding. For example, in some implementations, the method includes selecting a first set of one or more soft information values and receiving a read data command. The method further includes responding to the read data command by initiating performance of a data access operation to access data in a storage medium, the data access operation producing a syndrome weight; determining a first indicator based at least in part on the syndrome weight; based on the first indicator, selecting a second set of one or more soft information values; and decoding data obtained from the data access operation using the second set of one or more soft information values to produce a result.

Claims

1. A method of decoding data, the method comprising:

selecting a first set of one or more soft information values;

receiving a read data command; and

responding to the read data command by;

initiating performance of a data access operation to access data in a storage medium, the data access operation producing a syndrome weight;

determining a first indicator based at least in part on the syndrome weight;

based on the first indicator, selecting a second set of one or more soft information values; and

decoding data obtained from the data access operation using the second set of one or more soft information values to produce a result.

2. The method of claim 1, wherein the first set of one or more soft information values includes default LLR values for at least a portion of the storage medium.

3. The method of claim 1, wherein:

the storage medium includes a plurality of storage devices;

the data access operation produces a syndrome weight for each of the plurality of storage devices;

determining the first indicator comprises, for each storage device of the plurality of storage devices, determining a respective first indicator for the storage device based at least in part on the syndrome weight for the storage device; and

selecting a second set of one or more soft information values comprises, for each storage device of the plurality of storage devices, selecting, based on the respective first indicator for the storage device, a respective second set of one or more soft information values.

4. The method of claim 3, wherein the storage medium is distributed across multiple semiconductor die.

5. The method of claim 1, wherein the method is performed by a memory controller distinct from and coupled to the storage medium by one or more connections, and the data read commands are received from a device distinct from the memory controller.

6. A method of decoding data, the method comprising:

selecting a first set of one or more soft information values;

receiving a multiplicity of read data commands;

in accordance with the multiplicity of read data commands, initiating performance of data access operations to access data in a storage medium, the data access operations producing syndrome weights;

determining an average syndrome weight in accordance with the syndrome weights produced by the data access operations;

determining a first indicator based at least in part on the determined average syndrome weight;

based on the first indicator, selecting a second set of one or more soft information values; and

after selecting the second set of one or more soft information values, decoding data for a subsequent read data command using the second set of one or more soft information values.

7. The method of claim 6, wherein the first set of one or more soft information values includes default LLR values for at least a portion of the storage medium, and the default LLR values are updated based at least in part on the first indicator.

8. A method of decoding data, the method comprising:

selecting a first set of one or more soft information values;

receiving a read data command; and

responding to the read data command by;

initiating performance of a data access operation to access data in a storage medium, the data access operation producing a syndrome weight;

determining a first indicator based at least in part on the syndrome weight;

based on the first indicator, adjusting the first set of one or more soft information values to obtain a second set of one or more soft information values; and

decoding data obtained from the data access operation using the second set of one or more soft information values to produce a result.

9. The method of claim 8, wherein adjusting the first set of one or more soft information values comprises applying a predefined mathematical function to the first set of one or more soft information values to obtain the second set of one or more soft information values.

10. The method of claim 9, wherein the predefined mathematical function adds a predefined vector of values to the first set of one or more soft information values to obtain the second set of one or more soft information values.

11. The method of claim 8, wherein:

the storage medium includes a plurality of storage devices;

the data access operation produces a syndrome weight for each of the plurality of storage devices;

determining the first indicator comprises, for each storage device of the plurality of storage devices, determining a respective first indicator for the storage device based at least in part on the syndrome weight for the storage device; and

adjusting the first set of one or more soft information values to obtain a second set of one or more soft information values comprises, for each storage device of the plurality of storage devices, adjusting, based on the respective first indicator for the storage device, a respective first set of one or more soft information values to obtain a respective second set of one or more soft information values.

12. The method of claim 11, wherein the storage medium is distributed across multiple semiconductor die.

13. A device operable to decode data, comprising:

a storage medium interface for coupling the device to the storage medium; and

one or more modules, including a memory management module that includes one or more processors and memory storing one or more programs configured for execution by the one or more processors, the one or more modules coupled to the storage medium interface and configured to;

select a first set of one or more soft information values;

receive a read data command; and

respond to the read data command by;

initiating performance of a data access operation to access data in the storage medium, the data access operation producing a syndrome weight;

determining a first indicator based at least in part on the syndrome weight;

based on the first indicator, selecting a second set of one or more soft information values; and

decoding data obtained from the data access operation using the second set of one or more soft information values to produce a result.

14. The device of claim 13, wherein the first set of one or more soft information values includes default LLR values for at least a portion of the storage medium.

15. The device of claim 13, wherein:

the storage medium includes a plurality of storage devices;

the data access operation produces a syndrome weight for each of the plurality of storage devices;

determining the first indicator comprises, for each storage device of the plurality of storage devices, determining a respective first indicator for the storage device based at least in part on the syndrome weight for the storage device; and

selecting a second set of one or more soft information values comprises, for each storage device of the plurality of storage devices, selecting, based on the respective first indicator for the storage device, a respective second set of one or more soft information values.

16. The device of claim 15, wherein the storage medium is distributed across multiple semiconductor die.

17. A device operable to decode data, comprising:

a storage medium interface for coupling the device to the storage medium; and

one or more modules, including a memory management module that includes one or more processors and memory storing one or more programs configured for execution by the one or more processors, the one or more modules coupled to the storage medium interface and configured to;

select a first set of one or more soft information values;

receive a multiplicity of read data commands;

in accordance with the multiplicity of read data commands, initiate performance of data access operations to access data in the storage medium, the data access operations producing syndrome weights;

determine an average syndrome weight in accordance with the syndrome weights produced by the data access operations;

determine a first indicator based at least in part on the determined average syndrome weight;

based on the first indicator, select a second set of one or more soft information values; and

after selecting the second set of one or more soft information values, decode data for a subsequent read data command using the second set of one or more soft information values.

18. The device of claim 17, wherein the first set of one or more soft information values includes default LLR values for at least a portion of the storage medium, and the default LLR values are updated based at least in part on the first indicator.

19. A device operable to decode data, comprising:

a storage medium interface for coupling the device to the storage medium; and

one or more modules, including a memory management module that includes one or more processors and memory storing one or more programs configured for execution by the one or more processors, the one or more modules coupled to the storage medium interface and configured to;

select a first set of one or more soft information values;

receive a read data command; and

respond to the read data command by;

initiating performance of a data access operation to access data in the storage medium, the data access operation producing a syndrome weight;

determining a first indicator based at least in part on the syndrome weight;

based on the first indicator, adjusting the first set of one or more soft information values to obtain a second set of one or more soft information values; and

decoding data obtained from the data access operation using the second set of one or more soft information values to produce a result.

20. The device of claim 19, wherein adjusting the first set of one or more soft information values comprises applying a predefined mathematical function to the first set of one or more soft information values to obtain the second set of one or more soft information values.

21. The device of claim 20, wherein the predefined mathematical function adds a predefined vector of values to the first set of one or more soft information values to obtain the second set of one or more soft information values.

22. The device of claim 19, wherein:

the storage medium includes a plurality of storage devices;

the data access operation produces a syndrome weight for each of the plurality of storage devices;

determining the first indicator comprises, for each storage device of the plurality of storage devices, determining a respective first indicator for the storage device based at least in part on the syndrome weight for the storage device; and

adjusting the first set of one or more soft information values to obtain a second set of one or more soft information values comprises, for each storage device of the plurality of storage devices, adjusting, based on the respective first indicator for the storage device, a respective first set of one or more soft information values to obtain a respective second set of one or more soft information values.

23. The device of claim 22, wherein the storage medium is distributed across multiple semiconductor die.