System and method for structured LDPC code family with fixed code length and no puncturing

• US 8,495,450 B2
• Filed: 08/12/2010
• Issued: 07/23/2013
• Est. Priority Date: 08/24/2009
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Abu-Surra, Shadi, Pisek, Eran, Pi, Zhouyue
• Primary Examiner(s): Baderman, Scott
• Assistant Examiner(s): KUDIRKA, JOSEPH R
• Application Number:
  US12/855,442
• Publication Number:
  US 20110047433A1
• Time in Patent Office: 1,076 Days
• Field of Search: 714/752
• US Class Current: 714/752
• CPC Class Codes: H03M 13/033 Theoretical methods to calculate these checking codes
• CPC Class Codes: H03M 13/036 Heuristic code construction methods, i.e. code construction or code search based on using trial-and-error
• CPC Class Codes: H03M 13/1137 Partly parallel processing, i.e. sub-blocks or sub-groups of nodes being processed in parallel
• CPC Class Codes: H03M 13/116 Quasi-cyclic LDPC [QC-LDPC] codes, i.e. the parity-check matrix being composed of permutation or circulant sub-matrices
• CPC Class Codes: H03M 13/1165 QC-LDPC codes as defined for the digital video broadcasting [DVB] specifications, e.g. DVB-Satellite [DVB-S2]
• CPC Class Codes: H03M 13/118 Parity check matrix structured for simplifying encoding, e.g. by having a triangular or an approximate triangular structure H03M13/1165 takes precedence
• CPC Class Codes: H03M 13/6362 by puncturing
• CPC Class Codes: H03M 13/6516 Support of multiple code parameters, e.g. generalized Reed-Solomon decoder for a variety of generator polynomials or Galois fields
• CPC Class Codes: H03M 13/6525 3GPP LTE including E-UTRA
• CPC Class Codes: H03M 13/6544 IEEE 802.16 (WIMAX and broadband wireless access)
• CPC Class Codes: H04L 1/005 Iterative decoding, including iteration between signal detection and decoding operation
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence

Abstract

A family of low density parity check (LDPC) codes is generated based on a mother code having a highest code rate. The low density parity check (LDPC) codes include a codeword size of at least 1344. The LDPC codes also include a plurality of parity bits in a lower triangular form. The mother code is constructed by: selecting m number of rows and n number of columns; setting maximum column weights and row weights; designing a protograph matrix based on the set column weights and row weights and selected m and n; and selecting circulant blocks based on the protograph matrix.

Claims

1. For use in a wireless communication network, a method for constructing a low density parity check (LDPC) family of codes, the method comprising:

constructing a mother code having a highest code rate in the LDPC family of codes, wherein the mother code is constructed by;

selecting m number of rows and n number of columns;

setting maximum column weights and row weights;

designing a protograph matrix based on the set column weights and row weights and selected m and n;

selecting circulant blocks based on the protograph matrix; and

deriving a second code from the mother code by splitting each row of the mother code into two or more split rows and merging certain values from two or more split rows to form at least one row in the second code using splitting and merging rules that introduce no smaller cycles than those in the mother code.

2. The method as set forth in claim 1, wherein the mother code comprises a derived code rate comprising a rate-⅚

code.

3. The method as set forth in claim 1, wherein the second code comprises a second code rate that is lower than the highest code rate.

4. The method as set forth in claim 3, wherein the second code comprises a derived code rate comprising at least one of:

a rate-⅔

code;

a rate-½

code; and

a rate-¾

code.

5. The method as set forth in claim 3, wherein the deriving comprises at least one of:

splitting each row of the mother code into three rows using a first splitting rule; and

splitting each row of the mother code into two rows using a second splitting rule.

6. The method as set forth in claim 1, further comprising constructing at least one set of the splitting rules, wherein the constructing comprises:

determining a number of extra rows needed to construct a second protograph; and

deriving the extra rows from the protograph matrix.

7. The method as set forth in claim 1, wherein selecting the circulant blocks comprises:

lifting the second protograph matrix by a lifting factor of 28.

8. The method as set forth in claim 1, wherein selecting the circulant blocks comprises:

lifting the protograph matrix by a lifting factor of 2 to obtain a second protograph matrix; and

lifting the second protograph matrix by a lifting factor of 28.

9. For use in a wireless communications network, a low density parity check (LDPC) code implemented in a non-transitory, computer-readable medium, the LDPC code comprising:

a codeword size of at least 1344;

a plurality of information bits; and

a plurality of parity bits, wherein the plurality of parity bits comprises a lower triangular form, and wherein the LDPC code is based on a mother code, wherein the mother code is constructed by;

selecting m number of rows and n number of columns;

setting maximum column weights and row weights;

designing a protograph matrix based on the set column weights and row weights and selected m and n;

selecting circulant blocks based on the protograph matrix; and

deriving a second code from the mother code by splitting each row of the mother code into two or more split rows and merging certain values from two or more split rows to form at least one row in the second code using splitting and merging rules that introduce no smaller cycles than those in the mother code.

10. The LDPC code as set forth in claim 9, wherein the mother code comprises a derived code rate comprising a rate-⅚

code.

11. The LDPC code as set forth in claim 9, wherein the mother code comprises a highest code rate and the second code comprises a second code rate that is lower than the highest code rate.

12. The LDPC code as set forth in claim 11, wherein the second code comprises a derived code rate comprising at least one of:

a rate-⅔

code;

a rate-½

code; and

a rate-¾

code.

13. The LDPC code as set forth in claim 11, wherein the second code is derived by at least one of:

splitting each row of the mother code into three rows using a first splitting rule; and

splitting each row of the mother code into two rows using a second splitting rule.

14. The LDPC code as set forth in claim 9, wherein the LDPC code is derived from a 2X mother code, the 2X mother code constructed by:

lifting the protograph matrix by a lifting factor of 2 to obtain a second protograph matrix; and

lifting the second protograph matrix by a lifting factor of 28.

15. The LDPC code as set forth in claim 14, wherein the LDPC code comprises a codeword size of 2688.

16. For use in a wireless communications network, a method for performing error correction comprising using a low density parity check (LDPC) code from a LDPC family of codes in a non-transitory, computer-readable medium, the LDPC code comprising:

a codeword size of at least 1344;

a plurality of information bits; and

a plurality of parity bits, wherein the plurality of parity bits comprises a lower triangular form, and wherein the LDPC code is based on a mother code, wherein the mother code is constructed by;

selecting m number of rows and n number of columns;

setting maximum column weights and row weights;

designing a protograph matrix based on the set column weights and row weights and selected m and n;

selecting circulant blocks based on the protograph matrix; and

deriving a second code from the mother code by splitting each row of the mother code into two or more split rows and merging certain values from two or more split rows to form at least one row in the second code using splitting and merging rules that introduce no smaller cycles than those in the mother code.

17. The method as set forth in claim 16, wherein the LDPC code is one of:

the mother code; and

the derived second code, wherein the mother code comprises a rate-⅚

code and wherein the derived second code comprises a derived code rate comprising at least one of;

a rate-⅔

code;

a rate-½

code; and

a rate-¾

code.

18. The method as set forth in claim 17, wherein the derived second code is constructed by at least one of:

splitting each row of the mother code into three rows using a first splitting rule; and

splitting each row of the mother code into two rows using a second splitting rule.

19. The method as set forth in claim 16, wherein selecting the circulant blocks comprises:

lifting the second protograph matrix by a lifting factor of 28.

20. The method as set forth in claim 16, wherein selecting the circulant blocks comprises:

lifting the protograph matrix by a lifting factor of 2 to obtain a second protograph matrix; and

lifting the second protograph matrix by a lifting factor of 28.

21. The method as set forth in claim 16, wherein the LDPC code comprises a codeword size of 2688.