# US 2019/0356337 A1 · Enhanced puncturing and low-density parity-check (ldpc) code structure

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- Number: US 2019/0356337 A1
- Document ID: US20190356337A1
- Status: Published application
- Kind: A1
- Application number: 16/525,307
- Filed: 2019-07-29
- Published: 2019-11-21
- Earliest claimed: 2016-05-12
- Assignees: QUALCOMM Incorporated
- Applicants: QUALCOMM Incorporated
- Inventors: Thomas Joseph RICHARDSON; Shrinivas KUDEKAR
- Web page: https://patentgrep.com/patent/US20190356337A1

## CPC

- H03M 13/116: {Quasi-cyclic LDPC [QC-LDPC] codes, i.e. the parity-check matrix being composed of permutation or circulant sub-matrices}
- H03M 13/1174: {Parity-check or generator matrices built from sub-matrices representing known block codes such as, e.g. Hamming codes, e.g. generalized LDPC codes}
- H03M 13/036: {Heuristic code construction methods, i.e. code construction or code search based on using trial-and-error}
- H03M 13/1168: {wherein the sub-matrices have column and row weights greater than one, e.g. multi-diagonal sub-matrices}
- H03M 13/616: {Matrix operations, especially for generator matrices or check matrices, e.g. column or row permutations}
- H03M 13/6362: {by puncturing}
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)

## Abstract

Certain aspects of the present disclosure generally relate to techniques for enhanced puncturing and low-density parity-check (LDPC) code structure. A method for wireless communications by a transmitting device is provided. The method generally includes encoding a set of information bits based on a LDPC code to produce a code word, the LDPC code defined by a base matrix having a first number of variable nodes and a second number of check nodes; puncturing the code word according to a puncturing pattern designed to puncture bits corresponding to at least two of the variable nodes to produce a punctured code word; adding at least one additional parity bit for the at least two punctured variable nodes; and transmitting the punctured code word.

## Claims

### Claim 1

A method for wireless communications comprising:
encoding a set of information bits based on a low-density parity-check (LDPC) code to produce a code word, the LDPC code defined by a base graph having a first number of variable nodes and a second number of check nodes;
puncturing bits in the code word corresponding to at least two of the first number of variable nodes in the base graph to produce a punctured code word, wherein the base graph includes at least one additional variable node for the at least two punctured variable nodes, and wherein each additional variable node is connected to one check node, the check node coupled to a pair of punctured variable nodes; and
transmitting a signal associated with the punctured code word.

### Claim 2 (depends on 1)

The method of claim 1, wherein the at least two punctured variable nodes have a higher degree of connectivity to the check nodes than the other variable nodes in the base graph.

### Claim 3 (depends on 1)

The method of claim 1, wherein the at least two punctured variable nodes comprise M variable nodes, and wherein the at least one additional variable node comprises M−1 variable nodes.

### Claim 4 (depends on 1)

The method of claim 1, wherein the first number of variable nodes is 27 or 28 variable nodes.

### Claim 5 (depends on 1)

The method of claim 1, wherein the at least two punctured variable nodes have a first degree of connectivity to the check nodes that is lower than a second degree of connectivity of a variable node in a reference LDPC code.

### Claim 6 (depends on 1)

The method of claim 1, further comprising generating at least one lifted LDPC code by taking Z copies of the LDPC code defined by the base graph with the at least two punctured variable nodes and the at least one additional variable node.

### Claim 7

An apparatus comprising:
means for encoding a set of information bits based on a low-density parity-check (LDPC) code to produce a code word, the LDPC code defined by a base graph having a first number of variable nodes and a second number of check nodes;
means for puncturing bits in the code word corresponding to at least two of the first number of variable nodes in the base graph to produce a punctured code word, wherein the base graph includes at least one additional variable node for the at least two punctured variable nodes, and wherein each additional variable node is connected to one check node, the check node coupled to a pair of punctured variable nodes; and
means for transmitting a signal associated with the punctured code word.

### Claim 8 (depends on 7)

The apparatus of claim 7, wherein the at least two punctured variable nodes have a higher degree of connectivity to the check nodes than the other variable nodes in the base graph.

### Claim 9 (depends on 7)

The apparatus of claim 7, wherein the at least two punctured variable nodes comprise M variable nodes, and wherein the at least one additional variable node comprises M−1 variable nodes.

### Claim 10 (depends on 7)

The apparatus of claim 7, wherein the first number of variable nodes is 27 or 28 variable nodes.

### Claim 11 (depends on 7)

The apparatus of claim 7, wherein the at least two punctured variable nodes have a first degree of connectivity to the check nodes that is lower than a second degree of connectivity of a variable node in a reference LDPC code.

### Claim 12 (depends on 7)

The apparatus of claim 7, further comprising:
means for generating at least one lifted LDPC code by taking Z copies of the LDPC code defined by the base graph with the at least two punctured variable nodes and the at least one additional variable node.

### Claim 13

An apparatus comprising:
at least one processor coupled with a memory and configured to:
encode a set of information bits based on a low-density parity-check (LDPC) code to produce a code word, the LDPC code defined by a base graph having a first number of variable nodes and a second number of check nodes;
puncture bits in the code word corresponding to at least two of the first number of variable nodes in the base graph to produce a punctured code word, wherein the base graph includes at least one additional variable node for the at least two punctured variable nodes, and wherein each additional variable node is connected to one check node, the check node coupled to a pair of punctured variable nodes; and
transmit a signal associated with the punctured code word.

### Claim 14 (depends on 13)

The apparatus of claim 13, wherein the at least two punctured variable nodes have a higher degree of connectivity to the check nodes than the other variable nodes in the base graph.

### Claim 15 (depends on 13)

The apparatus of claim 13, wherein the at least two punctured variable nodes comprise M variable nodes, and wherein the at least one additional variable node comprises M−1 variable nodes.

### Claim 16 (depends on 13)

The apparatus of claim 13, wherein the first number of variable nodes is 27 or 28 variable nodes.

### Claim 17 (depends on 13)

The apparatus of claim 13, wherein the at least two punctured variable nodes have a first degree of connectivity to the check nodes that is lower than a second degree of connectivity of a variable node in a reference LDPC code.

### Claim 18 (depends on 13)

The apparatus of claim 13, wherein the at least one processor is further configured to:
generate at least one lifted LDPC code by taking Z copies of the LDPC code defined by the base graph with the at least two punctured variable nodes and the at least one additional variable node.

### Claim 19

A non-transitory computer readable medium having computer executable code stored thereon comprising:
code for encoding a set of information bits based on a low-density parity-check (LDPC) code to produce a code word, the LDPC code defined by a base graph having a first number of variable nodes and a second number of check nodes;
code for puncturing bits in the code word corresponding to at least two of the first number of variable nodes in the base graph to produce a punctured code word, wherein the base graph includes at least one additional variable node for the at least two punctured variable nodes, wherein each additional variable node is connected to one check node, the check node coupled to a pair of punctured variable nodes; and
code for transmitting a signal associated with the punctured code word.

### Claim 20 (depends on 19)

The non-transitory computer readable medium of claim 19, wherein the at least two punctured variable nodes have a higher degree of connectivity to the check nodes than the other variable nodes in the base graph.

### Claim 21 (depends on 19)

The non-transitory computer readable medium of claim 19, wherein the at least two punctured variable nodes comprise M variable nodes, and wherein the at least one additional variable node comprises M−1 variable nodes.

### Claim 22 (depends on 19)

The non-transitory computer readable medium of claim 19, wherein the first number of variable nodes is 27 or 28 variable nodes.

### Claim 23 (depends on 19)

The non-transitory computer readable medium of claim 19, wherein the at least two punctured variable nodes have a first degree of connectivity to the check nodes that is lower than a second degree of connectivity of a variable node in a reference LDPC code.

### Claim 24 (depends on 19)

The non-transitory computer readable medium of claim 19, further comprising:
code for generating at least one lifted LDPC code by taking Z copies of the LDPC code defined by the base graph with the at least two punctured variable nodes and the at least one additional variable node.