Enhanced polar code constructions by strategic placement of CRC bits

• US 10,644,836 B2
• Filed: 05/24/2019
• Issued: 05/05/2020
• Est. Priority Date: 06/01/2016
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Kudekar, Shrinivas, Richardson, Thomas Joseph
• Primary Examiner(s): Ahn, Sung S
• Application Number:
  US16/422,677
• Publication Number:
  US 20190280817A1
• Time in Patent Office: 347 Days
• CPC Class Codes: H03M 13/09 Error detection only, e.g. using cyclic redundancy check [CRC] codes or single parity bit
• CPC Class Codes: H03M 13/098 using single parity bit
• CPC Class Codes: H03M 13/13 Linear codes
• CPC Class Codes: H03M 13/3738 with judging correct decoding
• CPC Class Codes: H03M 13/3977 using sequential decoding, e.g. the Fano or stack algorithms
• CPC Class Codes: H03M 13/612 Aspects specific to channel or signal-to-noise ratio estimation H03M13/63 takes precedence
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/0063 Single parity check

Abstract

Certain aspects of the present disclosure relate to techniques and apparatus for improving decoding latency and performance of Polar codes. An exemplary method generally includes generating a codeword by encoding information bits, using a multi-dimensional interpretation of a polar code of length N, determining, based on one or more criteria, a plurality of locations within the codeword to insert error correction codes generating the error correction codes based on corresponding portions of the information bits, inserting the error correction codes at the determined plurality of locations, and transmitting the codeword. Other aspects, embodiments, and features are also claimed and described.

Claims

1. A method of wireless communications, comprising:

receiving a codeword encoded based on a polar code;

decoding the codeword based on the polar code to generate a sequence of information bits; and

verifying the portions of the sequence of information bits based on error detection codes inserted in the sequence of information bits at locations within the polar code having a rate of 1.

2. The method of claim 1, wherein the polar code is of length N, and wherein the codeword comprises:

information bits encoded using a first polar code of length K to obtain bits for transmission via M virtual channels; and

bits in each of the M virtual channels further encoded using a second polar code of length M, wherein N=K×

M.

3. The method of claim 1, wherein the decoding comprises:

decoding bits of the M virtual channels encoded with the second polar code that has a rate less than 1 using a first decoding approach, wherein the first decoding approach comprises performing successive cancelation (SC) list decoding; and

decoding bits of the M virtual channels encoded with the second polar code that has a rate of 1 using a second decoding approach, wherein the second decoding approach involves taking hard decisions.

4. The method of claim 3, further comprising:

replicating at least a portion of the received codeword; and

using the replicated portion of the codeword to reduce latency of the SC list decoding.

5. The method of claim 1, wherein the error detection codes comprise cyclic redundancy check (CRC) information.

6. The method of claim 5, wherein the error detection codes are generated from preset subsets of the information bits, wherein each subset has a same number of information bits.

7. The method of claim 5, wherein decoding the codeword comprises:

performing row-wise list-decoding of bits based on the CRC information; and

performing SC list decoding along columns after the row-wise decoding.

8. The method of claim 1, wherein decoding comprises:

determining, from the codeword, one or more codes indicating how to decode the portions of the codeword, wherein the one or more codes comprise at least one of a single parity check (SPC) code, a repetition code, or a rate zero code; and

decoding the codeword based on the one or more codes.

9. An apparatus for wireless communications, comprising:

a receiver configured to receive a codeword encoded based on a polar code;

at least one processor configured to;

decode the codeword based on the polar code to generate a sequence of information bits; and

verify the portions of the sequence of information bits based on error detection codes inserted in the sequence of information bits at locations within the polar code having a rate of 1; and

a memory coupled with the at least one processor.

10. The apparatus of claim 9, wherein the polar code is of length N, and wherein the codeword comprises:

information bits encoded using a first polar code of length K to obtain bits for transmission via M virtual channels; and

bits in each of the M virtual channels further encoded using a second polar code of length M, wherein N=K×

M.

11. The apparatus of claim 9, wherein the at least one processor is configured to decode the codeword by:

decoding bits of the M virtual channels encoded with the second polar code that has a rate less than 1 using a first decoding approach, wherein the first decoding approach comprises performing successive cancelation (SC) list decoding; and

decoding bits of the M virtual channels encoded with the second polar code that has a rate of 1 using a second decoding approach, wherein the second decoding approach involves taking hard decisions.

12. The apparatus of claim 11, wherein the at least one processor is further configured to:

replicate at least a portion of the received codeword; and

use the replicated portion of the codeword to reduce latency of the SC list decoding.

13. The apparatus of claim 9, wherein the error detection codes comprise cyclic redundancy check (CRC) information, generated from preset subsets of the information bits, wherein each subset has a same number of information bits.

14. The apparatus of claim 13, wherein the at least one processor is configured to decode the codeword by:

performing row-wise list-decoding of bits based on the CRC information; and

performing SC list decoding along columns after the row-wise decoding.

15. The method of claim 9, wherein the at least one processor is configured to decode the codeword by:

determining, from the codeword, one or more codes indicating how to decode the portions of the codeword, wherein the one or more codes comprise at least one of a single parity check (SPC) code, a repetition code, or a rate zero code; and

decoding the codeword based on the one or more codes.

16. A method of wireless communications, comprising:

receiving a codeword encoded based on a polar code;

decoding the codeword based on the polar code to generate a sequence of information bits; and

verifying the portions of the sequence of information bits based on error detection codes inserted in the sequence of information bits at a plurality of locations within the polar code where a correct decoding path falls off a decoding list associated with the polar code.

17. The method of claim 16, wherein the polar code is of length N, and wherein the codeword comprises:

information bits encoded using a first polar code of length K to obtain bits for transmission via M virtual channels; and

bits in each of the M virtual channels further encoded using a second polar code of length M, wherein N=K×

M.

18. The method of claim 16, wherein the decoding comprises:

decoding bits of the M virtual channels encoded with the second polar code that has a rate less than 1 using a first decoding approach, wherein the first decoding approach comprises performing successive cancelation (SC) list decoding; and

decoding bits of the M virtual channels encoded with the second polar code that has a rate of 1 using a second decoding approach, wherein the second decoding approach involves taking hard decisions.

19. The method of claim 18, further comprising:

replicating at least a portion of the received codeword; and

using the replicated portion of the codeword to reduce latency of the SC list decoding.

20. The method of claim 16, wherein the error detection codes comprise one or more parity bits.

21. The method of claim 16, wherein decoding comprises:

determining, from the codeword, one or more codes indicating how to decode the portions of the codeword, wherein the one or more codes comprise at least one of a single parity check (SPC) code, a repetition code, or a rate zero code; and

decoding the codeword based on the one or more codes.

22. The method of claim 16, wherein the locations of where a correct decoding path falls off a decoding list associated with the polar code are based, at least in part, on one or more decoding parameters.

23. The method of claim 22, wherein the one or more decoding parameters comprises at least one of a channel associated with the polar code, a code rate associated with the polar code, or a block-length associated with the polar code.

24. An apparatus for wireless communications, comprising:

a receiver configured to receive a codeword encoded based on a polar code;

at least one processor configured to;

decode the codeword based on the polar code to generate a sequence of information bits; and

verify the portions of the sequence of information bits based on error detection codes inserted in the sequence of information bits at a plurality of locations within the polar code where a correct decoding path falls off a decoding list associated with the polar code; and

a memory coupled with the at least one processor.

25. The apparatus of claim 24, wherein the polar code is of length N, and wherein the codeword comprises:

information bits encoded using a first polar code of length K to obtain bits for transmission via M virtual channels; and

bits in each of the M virtual channels further encoded using a second polar code of length M, wherein N=K×

M.

26. The apparatus of claim 24, wherein the at least one processor is configured to decode the codeword by:

decoding bits of the M virtual channels encoded with the second polar code that has a rate less than 1 using a first decoding approach, wherein the first decoding approach comprises performing successive cancelation (SC) list decoding; and

decoding bits of the M virtual channels encoded with the second polar code that has a rate of 1 using a second decoding approach, wherein the second decoding approach involves taking hard decisions.

27. The apparatus of claim 26, wherein the at least one processor is further configured to:

replicate at least a portion of the received codeword; and

use the replicated portion of the codeword to reduce latency of the SC list decoding.

28. The apparatus of claim 24, wherein the error detection codes comprise cyclic redundancy check (CRC) information, generated from preset subsets of the information bits, wherein each subset has a same number of information bits.

29. The apparatus of claim 28, wherein the at least one processor is configured to decode the codeword by:

performing row-wise list-decoding of bits based on the CRC information; and

performing SC list decoding along columns after the row-wise decoding.

30. The apparatus of claim 24, wherein the at least one processor is configured to decode the codeword by:

determining, from the codeword, one or more codes indicating how to decode the portions of the codeword, wherein the one or more codes comprise at least one of a single parity check (SPC) code, a repetition code, or a rate zero code; and

decoding the codeword based on the one or more codes.