Communication techniques involving pairwise orthogonality of adjacent rows in LPDC code
Certain aspects of the present disclosure provide low-density parity-check (LDPC) codes having pairwise orthogonality of adjacent rows, and a new decoder that exploits the pairwise row orthogonality for flexible decoder scheduling without performance loss. An apparatus includes a receiver configured to receive a codeword in accordance with a radio technology across a wireless channel via one or more antenna elements situated proximal the receiver. The apparatus includes at least one processor coupled with a memory and comprising decoder circuitry configured to decode the codeword based on a LDPC code to produce a set of information bits. The LDPC code is stored in the memory and defined by a base matrix having columns in which all adjacent rows are orthogonal in a last portion of the rows.
1. An apparatus for wireless communication, comprising:
a receiver configured to receive a codeword in accordance with a radio technology across a wireless channel via one or more antenna elements situated proximal the receiver; and
at least one processor coupled with a memory and comprising decoder circuitry configured to decode the codeword based on a low density parity check (LDPC) code to produce a set of information bits, wherein:
the LDPC code is stored in the memory and defined by a base matrix having a first number of columns corresponding to variable nodes of a base graph and a second number of rows corresponding to check nodes of the base graph, and
for each of the first number of columns, all adjacent rows are orthogonal in a last portion of the second number of rows.
2. The apparatus of claim 1 , wherein entries in the base matrix correspond to an edge between the variable node and the check node, of the base graph, associated with the entry in base matrix.
3. The apparatus of claim 2 , wherein entries in the base matrix include cyclic integer lifting values.
4. The apparatus of claim 2 , wherein in each of the first number of columns, at most one row of each pair of the adjacent orthogonal rows in the last portion of the rows has an entry.
5. The apparatus of claim 1 , wherein the last portion of the rows comprises at least the bottom twenty-one rows of the base matrix.
6. The apparatus of claim 1 , wherein the memory is configured to store at least a portion of the LDPC code.
7. The apparatus of claim 1 , wherein the at least one processor includes a layered decoder.
8. The apparatus of claim 1 , wherein the at least one processor is configured to decode the codeword based on a decoding schedule.
9. The apparatus of claim 8 , wherein the decoding schedule includes decoding the codeword based on the LDPC code by decoding sequentially row by row in the base matrix or by simultaneously decoding pairs of rows in the base matrix.
10. The apparatus of claim 9 , wherein the at least one processor is configured to select from two combinations of two rows from any three sequential rows in the last portion for the simultaneous decoding pairs of the decoding schedule.
11. The apparatus of claim 9 , wherein the row by row or pairs of rows is performed column by column.
12. The apparatus of claim 8 , wherein the decoding schedule includes skipping decoding portions of the base matrix that do not contain an associated entry.
13. The apparatus of claim 1 , wherein the LDPC code comprises a lifted LDPC code.
14. The apparatus of claim 1 , wherein:
the codeword comprises a punctured codeword,
the at least one processor further comprises a depuncturer configured to depuncture the codeword, and
the decoding comprises decoding the depunctured codeword.
15. An apparatus for wireless communication, comprising:
at least one processor coupled with a memory and comprising an encoder circuit configured to encode a set of information bits based on a low density parity check (LDPC) code to produce a codeword wherein:
the LDPC code is stored in the memory and defined by a base matrix having a first number of columns corresponding to variable nodes of a base graph and a second number of rows corresponding to check nodes of the base graph, and
for each of the first number of columns, all adjacent rows are orthogonal in a last portion of the second number of rows; and
a transmitter configured to transmit the codeword in accordance with a radio technology across a wireless channel via one or more antenna elements arranged proximal the transmitter.
16. The apparatus of claim 15 , wherein entries in the base matrix correspond to an edge between the variable node and the check node, of the base graph, associated with the entry in base matrix.
17. The apparatus of claim 16 , wherein entries in the base matrix are replaced cyclic integer lifting values.
18. The apparatus of claim 16 , wherein in each of the first number of columns, at most one row of each pair of the adjacent orthogonal rows in the last portion of the rows has an entry.
19. The apparatus of claim 15 , wherein the last portion of the rows comprises at least the bottom twenty-one rows of the base matrix.
20. The apparatus of claim 15 , wherein:
the at least one processor is configured to lifted the LDPC code by generating an integer number of copies of the base matrix; and
the LDPC code comprises a lifted LDPC code.
21. The apparatus of claim 15 , wherein:
the at least one processor further comprises a puncturer configured to puncture the codeword, and
the transmitting the codeword comprises transmitting the punctured codeword.
22. A method for wireless communication, comprising:
receiving a codeword in accordance with a radio technology across a wireless channel via one or more antenna elements situated proximal a receiver; and
decoding the codeword via decoder circuitry based on a low density parity check (LDPC) code to produce a set of information bits, wherein:
the LDPC code is stored and defined by a base matrix having a first number of columns corresponding to variable nodes of a base graph and a second number of rows corresponding to check nodes of the base graph, and
for each of the first number of columns, all adjacent rows are orthogonal in a last portion of the second number of rows.
23. The method of claim 22 , wherein in each of the first number of columns, at most one row of each pair of the adjacent orthogonal rows in the last portion of the rows has an entry.
24. The method of claim 22 , wherein the last portion of the rows comprises at least the bottom twenty-one rows of the base matrix.
25. The method of claim 22 , wherein:
the decoding is based on a decoding schedule; and
the decoding schedule includes decoding the codeword based on the LDPC code by decoding sequentially row by row in the base matrix or by simultaneously decoding pairs of rows in the base matrix.
26. The method of claim 25 , further comprising selecting from two combinations of two rows from any three sequential rows in the last portion for the simultaneous decoding pairs of the decoding schedule.
27. A method for wireless communication, comprising:
encoding a set of information bits with encoder circuitry based on a low density parity check (LDPC) code to produce a codeword wherein:
the LDPC code is defined by a base matrix having a first number of columns corresponding to variable nodes of a base graph and a second number of rows corresponding to check nodes of the base graph, and
for each of the first number of columns, all adjacent rows are orthogonal in a last portion of the second number of rows; and
transmitting the codeword in accordance with a radio technology across a wireless channel via one or more antenna elements.
28. The method of claim 27 , wherein in each of the first number of columns, at most one row of each pair of the adjacent orthogonal rows in the last portion of the rows has an entry.
29. The method of claim 27 , wherein the last portion of the rows comprises at least the bottom twenty-one rows of the base matrix.
30. The method of claim 27 , further comprising puncturing the codeword, wherein transmitting the codeword comprises transmitting the punctured codeword.