MEMORY CONTROLLER SUPPORTING RATE-COMPATIBLE PUNCTURED CODES

• US 20150234704A1
• Filed: 02/23/2015
• Published: 08/20/2015
• Est. Priority Date: 11/21/2007
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Radke, William H.
• Granted Patent: US 9,442,796 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• CPC Class Codes: G11C 29/52 Protection of memory contents; Detection of errors in memory contents
• CPC Class Codes: H03M 13/235 Encoding of convolutional codes, e.g. methods or arrangements for parallel or block-wise encoding
• CPC Class Codes: H03M 13/2933 using a block and a convolutional code H03M13/2957 takes precedence
• CPC Class Codes: H03M 13/353 Adaptation to the channel
• CPC Class Codes: H03M 13/6362 by puncturing
• CPC Class Codes: H03M 13/6375 Rate compatible punctured convolutional [RCPC] codes

Abstract

Apparatus and methods store data in a non-volatile solid state memory device according to a rate-compatible code, such as a rate-compatible convolutional code (RPCC). An example of such a memory device is a flash memory device. Data can initially be block encoded for error correction and detection. The block-coded data can be further convolutionally encoded. Convolutional-coded data can be punctured and stored in the memory device. The puncturing decreases the amount of memory used to store the data. Depending on conditions, the amount of puncturing can vary from no puncturing to a relatively high amount of puncturing to vary the amount of additional error correction provided and memory used. The punctured data can be decoded when data is to be read from the memory device.

Claims

1. A method of determining a code rate for a block of memory space in a non-volatile solid-state memory device, the method comprising:

determining whether a marginal condition exists for at least a portion of a block of data of the memory device; and

decreasing a code rate used with the block if the marginal condition exists.

2. The method of claim 1, wherein decreasing comprises reducing an amount of puncturing.

3. The method of claim 2, wherein the code rate after puncturing is in a range of 1/3 to 1/2.

4. The method of claim 2, wherein the punctured data is convolutionally encoded prior to puncturing.

5. The method of claim 2, wherein the punctured data corresponds to a convolutional code with a code rate of 1/4 prior to puncturing.

6. The method of claim 1, further comprising storing reference information in an unpunctured form from the one or more memory arrays, wherein the reference information indicates the code rate used.

7. The method of claim 1, wherein the non-volatile memory device corresponds to a NAND flash memory device.

8. An apparatus comprising:

one or more memory arrays of a non-volatile memory device; and

a memory controller configured to determine whether a marginal condition exists for at least a portion of a block of data of the memory device, and decrease a code rate used with the block if the marginal condition exists.

9. The apparatus of claim 8, wherein the memory controller is configured to generate punctured data and to reduce an amount of puncturing to decrease the code rate.

10. The apparatus of claim 9, wherein the code rate after puncturing is in a range of 1/3 to 1/2.

11. The apparatus of claim 9, wherein the punctured data is convolutionally encoded prior to puncturing.

12. The apparatus of claim 9, wherein the punctured data corresponds to a convolutional code with a code rate of 1/4 prior to puncturing.

13. The apparatus of claim 8, wherein the memory controller is configured to store reference information in an unpunctured form in the one or more memory arrays, wherein the reference information indicates the code rate.

14. The method of claim 8, wherein the non-volatile memory device corresponds to a NAND flash memory device.

15. A computer system comprising:

one or more processors; and

a memory device comprising;

one or more memory arrays of a non-volatile memory device; and

a memory controller configured to determine whether a marginal condition exists for at least a portion of a block of data of the memory device, and decrease a code rate used with the block if the marginal condition exists.

16. The computer system of claim 15, wherein the memory controller is configured to generate punctured data and to reduce an amount of puncturing to decrease the code rate.

17. The computer system of claim 16, wherein the code rate after puncturing is in a range of 1/3 to 1/2.

18. The computer system of claim 16, wherein the punctured data is convolutionally encoded prior to puncturing.

19. The computer system of claim 16, wherein the punctured data corresponds to a convolutional code with a code rate of 1/4 prior to puncturing.

20. The computer system of claim 15, wherein the memory controller is configured to store reference information in an unpunctured form in the one or more memory arrays, wherein the reference information indicates the code rate.