High performance, flexible, and compact low-density parity-check (LDPC) code

• US 10,291,354 B2
• Filed: 06/13/2017
• Issued: 05/14/2019
• Est. Priority Date: 06/14/2016
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Richardson, Thomas Joseph, Kudekar, Shrinivas
• Primary Examiner(s): Lamarre, Guy J
• Application Number:
  US15/622,008
• Publication Number:
  US 20170359148A1
• Time in Patent Office: 700 Days
• 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 13/1148 Structural properties of the code parity-check or generator matrix
• 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 13/616 Matrix operations, especially for generator matrices or check matrices, e.g. column or row permutations
• CPC Class Codes: H03M 13/6306 Error control coding in combination with Automatic Repeat reQuest [ARQ] and diversity transmission, e.g. coding schemes for the multiple transmission of the same information or the transmission of incremental redundancy H03M13/3761, H03M13/3769 and H03M13/635 take precedence
• CPC Class Codes: H03M 13/6393 Rate compatible low-density parity check [LDPC] codes
• CPC Class Codes: H03M 13/6505 Memory efficient implementations
• 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: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0056 Systems characterized by the type of code used H04L1/08 takes precedence
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0058 Block-coded modulation
• CPC Class Codes: H04L 1/0067 Rate matching H04L1/0013 and H04L1/08 take precedence
• CPC Class Codes: H04L 1/0068 by puncturing
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1819 with retransmission of additional or different redundancy

Abstract

Certain aspects of the present disclosure generally relate to techniques for puncturing of structured low-density parity-check (LDPC) codes. Certain aspects of the present disclosure generally relate to methods and apparatus for a high-performance, flexible, and compact LDPC code. Certain aspects can enable LDPC code designs to support large ranges of rates, blocklengths, and granularity, while being capable of fine incremental redundancy hybrid automatic repeat request (IR-HARQ) extension while maintaining good floor performance, a high-level of parallelism to deliver high throughout performance, and a low description complexity.

Claims

1. A method for wireless communication, comprising:

selecting, by selection circuitry, a first base graph, of a set of base graphs, the first base graph defining columns of variable nodes corresponding to information bits and rows of check nodes corresponding to parity checks, the set of base graphs associated with a set of families of lifted low-density parity-check (LDPC) codes, the first base graph associated with a first family of lifted LDPC codes of the set of families of lifted LDPC codes, for encoding information bits for transmission via a range of transmission rates, the first base graph selected based in part on a core rate supported by the first base graph and a highest transmission rate in the range of transmission rates;

encoding, by encoder circuitry, information bits using at least one lifted LDPC code from the first family of lifted LDPC codes associated with the selected first base graph for transmission at at least one transmission rate in the range of transmission rates to produce one or more code words; and

transmitting, via a transmitter coupled with an antenna, the one or more code words over a medium at the at least one transmission rate to a receiver for decoding the one or more code words.

2. The method of claim 1, wherein each family of the set of families of lifted LDPC codes is associated with a different base graph of the set of base graphs.

3. The method of claim 2, wherein each family of the set of families of lifted LDPC codes includes LDPC codes corresponding to a tower of clustered lifting size values of the base graph associated with that family, wherein the tower of clustered lifting size values comprises a plurality of sets of clustered lifting size values, each set of clustered lifting size values including lifting size values within a factor of each other, and the plurality of sets of clustered lifting size values being exponentially spaced.

4. The method of claim 2, wherein the different base graphs associated with the families of LDPC codes have an approximately equal maximum number of base variable nodes at full hybrid automatic repeat request (HARD) extension.

5. The method of claim 3, wherein:

each family of lifted LDPC codes comprises a set of lifted LDPC codes corresponding to a range of blocklengths supported by the tower of clustered lifting size values and a range of code rates supported by extension of the base graph associated with that family.

6. The method of claim 5, wherein:

the range of supported blocklengths is defined by the sets of clustered lifting size values associated with the family of lifted LDPC codes; and

the range of supported code rates is defined by the core rate of the family of lifted LDPC codes, corresponding to a core graph obtained by puncturing the base graph associated with the family of lifted LDPC codes, and a lowest code rate corresponding to an extended graph obtained by adding hybrid automatic repeat request (HARQ) extension bits to the base graph.

7. The method of claim 6, wherein selecting the first base graph comprises:

selecting the base graph that supports the core rate that is closest to the highest transmission rate of the range of transmission rates or if multiple base graphs support the core rate, selecting the base graph that has the smaller base graph size.

8. The method of claim 7, wherein encoding the information bits using the at least one lifted LDPC code comprises:

for the highest transmission rate in the range of transmission rates, using the lifted LDPC code from the first family of lifted LDPC codes that corresponds to the core rate; and

for other transmission rates in the range of transmission rates, using lifted LDPC codes from the first family of lifted LDPC codes that correspond to lower code rates obtained from the extended base graph of the selected first base graph.

9. The method of claim 1, wherein selecting the first base graph is further based on a lifting size value associated with the first family of lifted LDPC codes for a blocklength of the transmission.

10. The method of claim 9, wherein selecting the first base graph based on the lifting size value comprises:

for multiple base graphs that support a same transmission rate, selecting the base graph that is associated with a largest lifting size value for the blocklength of the transmission.

11. The method of claim 1, further comprising:

selecting, by the selection circuitry, a second base graph, of the set of base graphs, the second base graph associated with a second family of lifted LDPC of the set of families of lifted LDPC codes, for encoding other information bits for transmission via another range of transmission rates, the second base graph selected based in part on a core rate supported by the second base graph and a highest transmission rate in the other range of transmission rates.

12. An apparatus for wireless communication, comprising:

means for selecting a first base graph, of a set of base graphs, the first base graph defining columns of variable nodes corresponding to information bits and rows of check nodes corresponding to parity checks, the set of base graphs associated with a set of families of lifted low-density parity-check (LDPC) codes, the first base graph associated with a first family of lifted LDPC codes of the set of families of lifted LDPC codes, for encoding information bits for transmission via a range of transmission rates, the first base graph selected based in part on a core rate supported by the first base graph and a highest transmission rate in the range of transmission rates;

means for encoding information bits using at least one lifted LDPC code from the first family of lifted LDPC codes associated with the selected first base graph for transmission at at least one transmission rate in the range of transmission rates to produce one or more code words; and

means for transmitting the one or more code words over a medium at the at least one transmission rate to a receiver for decoding the one or more code words.

13. The apparatus of claim 12, wherein each family of the set of families of lifted LDPC codes is associated with a different base graph of the set of base graphs.

14. The apparatus of claim 13, wherein each family of the set of families of lifted LDPC codes includes LDPC codes corresponding to a tower of clustered lifting size values of the base graph associated with that family, wherein the tower of clustered lifting size values comprises a plurality of sets of clustered lifting size values, each set of clustered lifting size values including lifting size values within a factor of each other, and the plurality of sets of clustered lifting size values being exponentially spaced.

15. The apparatus of claim 13, wherein the different base graphs associated with the families of LDPC codes have an approximately equal maximum number of base variable nodes at full hybrid automatic repeat request (HARD) extension.

16. The apparatus of claim 14, wherein:

each family of lifted LDPC codes comprises a set of lifted LDPC codes corresponding to a range of blocklengths supported by the tower of clustered lifting size values and a range of code rates supported by extension of the base graph associated with that family.

17. The apparatus of claim 16, wherein:

the range of supported blocklengths is defined by the sets of clustered lifting size values associated with the family of lifted LDPC codes; and

the range of supported code rates is defined by the core rate of the family of lifted LDPC codes, corresponding to a core graph obtained by puncturing the base graph associated with the family of lifted LDPC codes, and a lowest code rate corresponding to an extended graph obtained by adding hybrid automatic repeat request (HARQ) extension bits to the base graph.

18. The apparatus of claim 17, wherein means for selecting the first base graph comprises:

means for selecting the base graph that supports the core rate that is closest to the highest transmission rate of the range of transmission rates or if multiple base graphs support the core rate, selecting the base graph that has the smaller base graph size.

19. The apparatus of claim 18, wherein means for encoding the information bits using the at least one lifted LDPC code comprises:

for the highest transmission rate in the range of transmission rates, means for using the lifted LDPC code from the first family of lifted LDPC codes that corresponds to the core; and

for other transmission rates in the range of transmission rates, means for using lifted LDPC codes from the first family of lifted LDPC codes that correspond to lower code rates obtained from the extended base graph of the selected first base graph.

20. The apparatus of claim 19, wherein selecting the first base graph is further based on a lifting size value associated with the first family of lifted LDPC codes for a blocklength of the transmission.

21. The apparatus of claim 20, wherein means for selecting the first base graph based on the lifting size value comprises:

for multiple base graphs that support a same transmission rate, means for selecting the base graph that is associated with a largest lifting size value for the blocklength of the transmission.

22. An apparatus for wireless communication, comprising:

at least one processor coupled with a memory and configured to;

select a first base graph, of a set of base graphs, the first base graph defining columns of variable nodes corresponding to information bits and rows of check nodes corresponding to parity checks, the set of base graphs associated with a set of families of lifted low-density parity-check (LDPC) codes, the first base graph associated with a first family of lifted LDPC codes of the set of families of lifted LDPC codes, for encoding information bits for transmission via a range of transmission rates, the first base graph selected based in part on a core rate supported by the first base graph and a highest transmission rate in the range of transmission rates; and

encode information bits using at least one lifted LDPC code from the first family of lifted LDPC codes associated with the selected first base graph for transmission at at least one transmission rate in the range of transmission rates to produce one or more code words; and

a transmitter configured to transmit the one or more code words over a medium at the at least one transmission rate to a receiver for decoding the one or more code words.

23. The apparatus of claim 22, wherein each family of the set of families of lifted LDPC codes is associated with a different base graph of the set of base graphs.

24. The apparatus of claim 23, wherein each family of the set of families of lifted LDPC codes includes LDPC codes corresponding to a tower of clustered lifting size values of the base graph associated with that family, wherein the tower of clustered lifting size values comprises a plurality of sets of clustered lifting size values, each set of clustered lifting size values including lifting size values within a factor of each other, and the plurality of sets of clustered lifting size values being exponentially spaced.

25. The apparatus of claim 23, wherein the different base graphs associated with the families of LDPC codes have an approximately equal maximum number of base variable nodes at full hybrid automatic repeat request (HARD) extension.

26. The apparatus of claim 24, wherein:

each family of lifted LDPC codes comprises a set of lifted LDPC codes corresponding to a range of blocklengths supported by the tower of clustered lifting size values and a range of code rates supported by extension of the base graph associated with that family.

27. The apparatus of claim 22, wherein the at least one processor is configured to encode the information bits by:

for the highest transmission rate in the range of transmission rates, using the lifted LDPC code from the first family of lifted LDPC codes that corresponds to the core rate; and

for other transmission rates in the range of transmission rates, using lifted LDPC codes from the first family of lifted LDPC codes that correspond to lower code rates obtained from the extended base graph of the selected first base graph.

28. The apparatus of claim 22, wherein the at least one processor is configured to select the first base graph based on the lifting size value by:

for multiple base graphs that support a same transmission rate, selecting the base graph that is associated with a largest lifting size value for the blocklength of the transmission.

29. A non-transitory computer readable medium having computer executable code stored thereon for wireless communication, comprising:

code for selecting a first base graph, of a set of base graphs, the first base graph defining columns of variable nodes corresponding to information bits and rows of check nodes corresponding to parity checks, the set of base graphs associated with a set of families of lifted low-density parity-check (LDPC) codes, the first base graph associated with a first family of lifted LDPC codes of the set of families of lifted LDPC codes, for encoding information bits for transmission via a range of transmission rates, the first base graph selected based in part on a core rate supported by the first base graph and a highest transmission rate in the range of transmission rates;

code for encoding information bits using at least one lifted LDPC code from the first family of lifted LDPC codes associated with the selected first base graph for transmission at at least one transmission rate in the range of transmission rates to produce one or more code words; and

code for transmitting the one or more code words over a medium at the at least one transmission rate to a receiver for decoding the one or more code words.

30. The non-transitory computer readable medium of claim 29, wherein each family of the set of families of lifted LDPC codes includes LDPC codes corresponding to a tower of clustered lifting size values of the base graph associated with that family, wherein the tower of clustered lifting size values comprises a plurality of sets of clustered lifting size values, each set of clustered lifting size values including lifting size values within a factor of each other, and the plurality of sets of clustered lifting size values being exponentially spaced.

31. The non-transitory computer readable medium of claim 29, further comprising:

for the highest transmission rate in the range of transmission rates, code for using the lifted LDPC code from the first family of lifted LDPC codes that corresponds to the core rate; and

for other transmission rates in the range of transmission rates, code for using lifted LDPC codes from the first family of lifted LDPC codes that correspond to lower code rates obtained from the extended base graph of the selected first base graph.