Method for selecting low density parity check (LDPC) code used for encoding of variable length data
View Patent ↗A method for selecting a low-density parity-check (LDPC) code for encoding variable sized data used in data communication systems. The method selects a LPCD code from a plurality of LDPC codes of different codeword lengths and code rates; by calculating a number of shortening N shortened bits and a number of puncturing N punctured bits for each of the plurality of LDPC codes, and determines a selected LDPC code from the plurality of shortened and punctured LDPC codes meeting a performance criterion.
1. A method for selecting a low-density parity-check (LDPC) code used for encoding variable sized data, the method comprising the steps of:
providing a plurality of LDPC codes of different codeword lengths and code rates;
calculating a number of shortening N shortened bits for each of the plurality of LDPC codes;
calculating a number of puncturing N punctured bits for each of the plurality of LDPC codes;
providing a performance criterion;
determining, in a computer processor, a selected LDPC code from the plurality of shortened LDPC codes and the plurality of punctured LDPC codes meeting the performance criterion; and
encoding data using the selected LDPC code.
2. The method according to claim 1 further comprising the steps of:
providing a plurality of performance criteria; and
determining a subsequent subset when each of the plurality of performance criteria is applied to the subsets of LDPC codes meeting previous criteria.
3. The method according to claim 1 , wherein the performance criterion is selected from the group consisting of a range of effective coding rates, a range of basic coding rates, a range of numbers of transmission symbols, a range of N punctured , a range of N shortened , a range of parity bits in LDPC codewords, a range for normalized shortening to puncturing ratio, q normalized , and a combination thereof.
4. The method according to claim 1 , wherein the performance criterion is selected from the group consisting of a minimum effective coding rate, a minimum basic coding rate, a minimum number of transmission symbols, a minimum for N punctured , a maximum for N shortened , a maximum number of parity bits in LDPC codewords, a maximum for normalized shortening to puncturing ratio, q normalized , and a combination thereof.
5. The method of claim 1 further comprising the steps of:
selecting N shortened variable nodes from the selected LDPC code;
ensuring a uniform or a close to uniform row weight distribution after removing columns corresponding to the selected N shortened variable nodes; and
ensuring a new column weight distribution as close as possible to an original column weight distribution after removing the columns corresponded to the selected N shortened variable nodes.
6. The method of claim 5 , wherein the step of selecting N shortened variable nodes further comprises the step of selecting variable nodes belonging to consecutive columns in of the selected LDPC code.
7. The method of claim 5 , wherein the ensuring a new column weight distribution step further comprises the step of prearranging columns of the data portion H d of the plurality of LDPC codes.
8. The method of claim 1 further comprising the steps of:
selecting N punctured variable nodes from the selected LDPC code; ensuring each of the selected N punctured variable nodes is connected to fewest possible check nodes; and
ensuring that all of the selected N punctured nodes are connected to most possible check nodes.
9. The method of claim 8 wherein the ensuring further comprises the step of selecting variable nodes that belongs to consecutive columns in the selected LDPC code.
10. A device encoding data using a selected LDPC code obtained by:
providing a plurality of LDPC codes of different codeword lengths and code rates;
calculating a number of shortening N shortened bits for each of the plurality of LDPC codes;
calculating a number of puncturing N punctured bits for each of the plurality of LDPC codes;
providing a performance criterion;
determining a selected LDPC code from the plurality of shortened LDPC codes and the plurality of punctured LDPC codes meeting the performance; and
providing the selected LDPC code.
11. A storage medium readable by a computer encoding a computer program for execution by the computer to carry out a method for selecting a low-density parity-check (LDPC) code used for encoding variable sized data, the method comprising:
providing a plurality of LDPC codes of different codeword lengths and code rates;
calculating a number of shortening N shortened bits for each of the plurality of LDPC codes;
calculating a number of puncturing N punctured bits for each of the plurality of LDPC codes;
providing a performance criterion;
determining a selected LDPC code from the plurality of shortened LDPC codes and the plurality of punctured LDPC codes meeting the performance criterion; and encoding data using the selected LDPC code.
12. The storage medium according to claim 11 , wherein the method further comprises:
providing a plurality of performance criteria; and
determining a subsequent subset when each of the plurality of performance criteria is applied to the subsets of LDPC codes meeting previous criteria.
13. The storage medium according to claim 11 , wherein the performance criterion is selected from the group consisting of a range of effective coding rates, a range of basic coding rates, a range of numbers of transmission symbols, a range of N punctured , a range of N shortened , a range of parity bits in LDPC codewords, a range for normalized shortening to puncturing ratio, q normalized , and a combination thereof.
14. The storage medium according to claim 11 , wherein the performance criterion is selected from the group consisting of a minimum effective coding rate, a minimum basic coding rate, a minimum number of transmission symbols, a minimum for N punctured , a maximum for N shortened , a maximum number of parity bits in LDPC codewords, a maximum for normalized shortening to puncturing ratio, q normalized , and a combination thereof.
15. The storage medium according to claim 11 , wherein the method further comprises:
selecting N shortened variable nodes from the selected LDPC code;
ensuring a uniform or a close to uniform row weight distribution after removing columns corresponding to the selected N shortened variable nodes; and
ensuring a new column weight distribution as close as possible to an original column weight distribution after removing the columns corresponded to the selected N shortened variable nodes.
16. The storage medium according to claim 11 , wherein the selecting N shortened variable nodes further comprises selecting variable nodes belonging to consecutive columns in of the selected LDPC code.
17. The storage medium according to claim 11 , wherein the ensuring a new column weight distribution step further comprises prearranging columns of the data portion H d of the plurality of LDPC codes.
18. The storage medium according to claim 11 , wherein the method further comprises:
selecting N punctured variable nodes from the selected LDPC code; ensuring each of the selected N punctured variable nodes is connected to fewest possible check nodes; and
ensuring that all of the selected N punctured nodes are connected to most possible check nodes.
19. The storage medium according to claim 11 , wherein the ensuring further comprises selecting variable nodes that belongs to consecutive columns in the selected LDPC code.