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1. (WO2019032881) SELF-DECODABLE RETRANSMISSION FOR LDPC CODE BASED HARQ SYSTEMS
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CLAIMS

What is claimed is:

1. A method for wireless communication, comprising:

encoding a set of information bits using a lifted low-density parity-check (LDPC) code for a lifting size value Z from a base graph, the lifted LDPC code having a plurality of variable nodes corresponding to one or more information bits and parity bits and a plurality of check nodes, to generate an encoded bit stream; and

transmitting a redundancy version corresponding to the set of information bits, the redundancy version either comprising a contiguous set of bits from a circular buffer storing the encoded bit stream or a re-ordered set of bits from the encoded bit stream.

2. The method of claim 1, further comprising:

selecting between the contiguous set of bits and the re-ordered set of bits, wherein the transmitting is based at least in part on the selection.

3. The method of claim 1, further comprising:

re-ordering bits in the encoded bit stream to create the re-ordered set of bits; and

writing the re-ordered set of bits to a second circular buffer.

4. The method of claim 3, wherein transmitting the redundancy version comprises:

transmitting a contiguous set of bits from the second circular buffer.

5. The method of claim 3, further comprising:

selecting a starting bit for reading the contiguous set of bits from the second circular buffer based at least in part on the redundancy version.

6. The method of claim 1, further comprising:

selecting stored bits from the circular buffer for a retransmission based at least in part on the redundancy version; and

re-ordering the stored bits upon selection, wherein the re-ordered set of bits comprises the re-ordered stored bits.

7. The method of claim 1, further comprising:

selecting bits by reading stored bits non-contiguously from the circular buffer, wherein the re-ordered set of bits comprises the selected bits.

8. The method of claim 1, further comprising:

re-ordering bits in the encoded bit stream for a retransmission based at least in part on a code rate of the encoded bit stream.

9. The method of claim 8, wherein re-ordering bits in the encoded bit stream for the retransmission comprises:

generating a matrix of bits by allocating bits of the encoded bit stream to a plurality of rows and columns, wherein a first equal number of bits is allocated to each row and a second equal number of bits is allocated to each column;

the method further comprising:

performing a random circular shift on bits in each row of the plurality of rows;

selecting bits in order of increasing row index followed by increasing column index; and

storing the selected bits.

10. The method of claim 9, wherein information bits in the set of information bits in the encoded bit stream are distributed evenly across the selected bits.

11. The method of claim 9, wherein each row includes Z bits.

12. The method of claim 8, wherein the re-ordering is a structured re-ordering that ensures that retransmissions are self-decodable for all redundancy versions.

13. The method of claim 8, wherein the re-ordering of the bits in the encoded bit stream is a random re-ordering.

14. The method of claim 1, wherein the lifted LDPC code is restricted to a lifted LDPC code corresponding to a code rate higher than a lowest code rate associated with the base graph.

15. The method of claim 14, wherein the lowest code rate associated with the base graph comprises a mother code.

16. The method of claim 15, further comprising:

restricting a size of the mother code for an original transmission and for retransmissions of the set of information bits.

17. An apparatus for wireless communication, comprising: means for encoding a set of information bits using a lifted low-density parity -check (LDPC) code for a lifting size value Z from a base graph, the lifted LDPC code having a plurality of variable nodes corresponding to one or more information bits and parity bits and a plurality of check nodes, to generate an encoded bit stream; and

means for transmitting either a contiguous set of bits from a first circular buffer storing the encoded bit stream or a contiguous set of bits from a second circular buffer storing re-ordered bits from the encoded bit stream based at least in part on a redundancy version for the transmitting.

18. The apparatus of claim 17, further comprising:

means for selecting between the contiguous set of bits and the re-ordered set of bits, wherein the transmitting is based at least in part on the selection.

19. The apparatus of claim 17, further comprising:

means for re-ordering bits in the encoded bit stream to create the re-ordered set of bits; and

means for writing the re-ordered set of bits to a second circular buffer.

20. The apparatus of claim 19, further comprising:

means for transmitting a contiguous set of bits from the second circular buffer.

21. The apparatus of claim 19, further comprising:

means for selecting a starting bit for reading the contiguous set of bits from the second circular buffer based at least in part on the redundancy version.

22. The apparatus of claim 17, further comprising:

means for selecting stored bits from the circular buffer for a retransmission based at least in part on the redundancy version; and

means for re-ordering the stored bits upon selection, wherein the re-ordered set of bits comprises the re-ordered stored bits.

23. The apparatus of claim 17, further comprising:

means for selecting bits by reading stored bits non-contiguously from the circular buffer, wherein the re-ordered set of bits comprises the selected bits.

24. The apparatus of claim 17, wherein further comprising: means for re-ordering bits in the encoded bit stream for a retransmission based at least in part on a code rate of the encoded bit stream.

25. The apparatus of claim 24, wherein the means for re-ordering bits in the encoded bit stream for the retransmission further comprise:

means for generating a matrix of bits by allocating bits of the encoded bit stream to a plurality of rows and columns, wherein a first equal number of bits is allocated to each row and a second equal number of bits is allocated to each column;

the apparatus further comprising:

means for performing a random circular shift on bits in each row of the plurality of rows;

means for selecting bits in order of increasing row index followed by increasing column index; and

means for storing the selected bits.

26. The apparatus of claim 25, wherein information bits in the set of information bits in the encoded bit stream are distributed evenly across the selected bits.

27. The apparatus of claim 24, wherein the re-ordering is a structured re-ordering that ensures that retransmissions are self-decodable for all redundancy versions.

28. The apparatus of claim 17, wherein the lifted LDPC code is restricted to a lifted LDPC code corresponding to a code rate higher than a lowest code rate associated with the base graph, and wherein the lowest code rate associated with the base graph comprises a mother code;

the apparatus further comprising means for restricting a size of the mother code for an original transmission and for retransmissions of the set of information bits.

29. An apparatus for wireless communication, comprising: a processor;

memory in electronic communication with the processor; and

instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to:

encode a set of information bits using a lifted low-density parity-check (LDPC) code for a lifting size value Z from a base graph, the lifted LDPC code having a plurality of variable nodes corresponding to one or more information bits and parity bits and a plurality of check nodes, to generate an encoded bit stream; and transmit either a contiguous set of bits from a first circular buffer storing the encoded bit stream or a contiguous set of bits from a second circular buffer storing re-ordered bits from the encoded bit stream based at least in part on a redundancy version for the transmitting.

30. A non-transitory computer readable medium storing code for wireless communication, the code comprising instructions executable by a processor to:

encode a set of information bits using a lifted low-density parity-check (LDPC) code for a lifting size value Z from a base graph, the lifted LDPC code having a plurality of variable nodes corresponding to one or more information bits and parity bits and a plurality of check nodes, to generate an encoded bit stream; and

transmit either a contiguous set of bits from a first circular buffer storing the encoded bit stream or a contiguous set of bits from a second circular buffer storing re-ordered bits from the encoded bit stream based at least in part on a redundancy version for the transmitting.