High performance, flexible, and compact low-density parity-check (LDPC) code
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.
1. A method for wireless communication by a transmitting device, comprising:
selecting a base graph, of a set of base graphs, for encoding information bits for transmission at one or more transmission rates in a range of transmission rates, the base graph selected based at least in part on a highest transmission rate in the range of transmission rates, each base graph of the set of base graphs associated with a family of lifted low-density parity-check (LDPC) codes;
encoding the information bits using at least one lifted LDPC code from the family of lifted LDPC codes associated with the base graph for transmission at the one or more transmission rates to produce one or more code words; and
transmitting the one or more code words over a medium.
2. The method of claim 1 , wherein selecting the base graph comprises:
selecting a first base graph for transmission rates above a threshold transmission rate; and
selecting a second base graph for transmission rate below the threshold transmission rate.
3. The method of claim 1 , wherein each base graph of the set of base graphs is associated with a different core rate.
4. The method of claim 1 , wherein the set of base graphs have an approximately equal maximum number of base variable nodes at full hybrid automatic repeat request (HARD) extension.
5. The method of claim 1 , wherein each base graph of the set of base graph is associated with a different set of lifting size values.
6. The method of claim 5 , wherein the sets of lifting size values comprise a tower of clustered liftings, the tower of clustered liftings including exponentially spaced clusters of liftings within a factor of each other.
7. The method of claim 5 , wherein each family of lifted LDPC codes corresponds to a range of blocklengths associated with the set of clustered lifting size values and a range of code rates, the range of code rates corresponding to different extensions of the base graph associated with the family of LDPC codes.
8. The method of claim 7 , wherein selecting the base graph is further based, at least in part, on at least one of: the supported range of blocklengths or codes rates by the family LDPC codes associated with the base graph.
9. The method of claim 8 , wherein:
the supported range of code rates includes a core rate corresponding to a highest code rate in the range of code rates, the core rate associated with a core graph of the base graph, the core graph obtained by puncturing the base graph; and
the supported range of code rates includes a lowest code rate corresponding to an extended graph of the base graph, the extended graph obtained by adding hybrid automatic repeat request (HARD) extension bits to the base graph.
10. The method of claim 9 , wherein selecting the base graph is further based, at least in part, on the core rate and a highest lifting size value associated with the base graph.
11. The method of claim 9 , wherein encoding the information bits comprises:
for the highest transmission rate in the range of transmission rates, using the lifted LDPC code corresponding to the core rate; and
for lower transmission rates in the range of transmission rates, using lifted LDPC codes corresponding to lower code rates obtained from the extended graph.
12. An apparatus for wireless communication, comprising:
at least one processor; and
a memory coupled to the at least one processor, the memory comprising code executable by the at least one processor to cause the apparatus to:
select a base graph, of a set of base graphs, for encoding information bits for transmission at one or more transmission rates in a range of transmission rates, the base graph selected based at least in part on a highest transmission rate in the range of transmission rates, each base graph of the set of base graphs associated with a family of lifted low-density parity-check (LDPC) codes; and
encode the information bits using at least one lifted LDPC code from the family of lifted LDPC codes associated with the base graph for transmission at the one or more transmission rates to produce one or more code words; and
a transmitter configured to transmit the one or more code words over a medium.
13. The apparatus of claim 12 , wherein the apparatus is configured to select the base graph by:
selecting a first base graph for transmission rates above a threshold transmission rate; and
selecting a second base graph for transmission rate below the threshold transmission rate.
14. The apparatus of claim 12 , wherein each base graph of the set of base graphs is associated with a different core rate.
15. The apparatus of claim 12 , wherein the set of base graphs have an approximately equal maximum number of base variable nodes at full hybrid automatic repeat request (HARD) extension.
16. The apparatus of claim 12 , wherein each base graph of the set of base graph is associated with a different set of lifting size values.
17. The apparatus of claim 16 , wherein the sets of lifting size values comprise a tower of clustered liftings, the tower of clustered liftings including exponentially spaced clusters of liftings within a factor of each other.
18. The apparatus of claim 16 , wherein each family of lifted LDPC codes corresponds to a range of blocklengths associated with the set of clustered lifting size values and a range of code rates, the range of code rates corresponding to different extensions of the base graph associated with the family of LDPC codes.
19. The apparatus of claim 18 , wherein the apparatus is configured to select the base graph further based, at least in part, on at least one of:
the supported range of blocklengths or codes rates by the family LDPC codes associated with the base graph.
20. The apparatus of claim 19 , wherein:
the supported range of code rates includes a core rate corresponding to a highest code rate in the range of code rates, the core rate associated with a core graph of the base graph, the core graph obtained by puncturing the base graph; and
the supported range of code rates includes a lowest code rate corresponding to an extended graph of the base graph, the extended graph obtained by adding hybrid automatic repeat request (HARD) extension bits to the base graph.
21. The apparatus of claim 20 , wherein the apparatus is configured to select the base graph further based, at least in part, on the core rate and a highest lifting size value associated with the base graph.
22. The apparatus of claim 20 , wherein the apparatus is configured to encode the information bits by:
for the highest transmission rate in the range of transmission rates, using the lifted LDPC code corresponding to the core rate; and
for lower transmission rates in the range of transmission rates, using lifted LDPC codes corresponding to lower code rates obtained from the extended graph.
23. An apparatus for wireless communication, comprising:
means for selecting a base graph, of a set of base graphs, for encoding information bits for transmission at one or more transmission rates in a range of transmission rates, the base graph selected based at least in part on a highest transmission rate in the range of transmission rates, each base graph of the set of base graphs associated with a family of lifted low-density parity-check (LDPC) codes;
means for encoding the information bits using at least one lifted LDPC code from the family of lifted LDPC codes associated with the base graph for transmission at the one or more transmission rates to produce one or more code words; and
means for transmitting the one or more code words over a medium.
24. The apparatus of claim 23 , wherein selecting the base graph comprises:
selecting a first base graph for transmission rates above a threshold transmission rate; and
selecting a second base graph for transmission rate below the threshold transmission rate.
25. The apparatus of claim 23 , wherein each base graph of the set of base graphs is associated with a different core rate.
26. The apparatus of claim 25 , wherein each family of lifted LDPC codes corresponds to a range of blocklengths associated with the set of clustered lifting size values and a range of code rates, the range of code rates corresponding to different extensions of the base graph associated with the family of LDPC codes.
27. The apparatus of claim 26 , wherein selecting the base graph is further based, at least in part, on at least one of: the supported range of blocklengths or codes rates by the family LDPC codes associated with the base graph.
28. The apparatus of claim 27 , wherein:
the supported range of code rates includes a core rate corresponding to a highest code rate in the range of code rates, the core rate associated with a core graph of the base graph, the core graph obtained by puncturing the base graph; and
the supported range of code rates includes a lowest code rate corresponding to an extended graph of the base graph, the extended graph obtained by adding hybrid automatic repeat request (HARD) extension bits to the base graph.
29. The apparatus of claim 28 , wherein encoding the information bits comprises:
for the highest transmission rate in the range of transmission rates, using the lifted LDPC code corresponding to the core rate; and
for lower transmission rates in the range of transmission rates, using lifted LDPC codes corresponding to lower code rates obtained from the extended graph.
30. A non-transitory computer readable medium that stores instructions that when executed by a transmitting device cause the transmitting device to perform a method for wireless communication, the method comprising:
selecting a base graph, of a set of base graphs, for encoding information bits for transmission at one or more transmission rates in a range of transmission rates, the base graph selected based at least in part on a highest transmission rate in the range of transmission rates, each base graph of the set of base graphs associated with a family of lifted low-density parity-check (LDPC) codes;
encoding the information bits using at least one lifted LDPC code from the family of lifted LDPC codes associated with the base graph for transmission at the one or more transmission rates to produce one or more code words; and
transmitting the one or more code words over a medium.
31. The method of claim 1 , wherein the base graph is selected further based on a blocklength associated with the transmission.
32. The apparatus of claim 12 , wherein the base graph is selected further based on a blocklength associated with the transmission.
33. The apparatus of claim 23 , wherein the base graph is selected further based on a blocklength associated with the transmission.
34. The non-transitory computer readable medium of claim 30 , wherein the base graph is selected further based on a blocklength associated with the transmission.