Dynamic frozen bits and error detection for polar codes
Methods, systems, and devices for wireless communication are described for dynamic frozen bits of polar codes for early termination and performance improvement. A wireless device may receive a signal comprising a codeword encoded using a polar code. The wireless device may perform decoding of the codeword including at least: parity check of a first subset of decoding paths for making a decision on early termination of decoding of the codeword based on dynamic frozen bits, and generating path metrics for a second subset of the decoding paths that each pass the parity check based on the dynamic frozen bits, and performing error detection on a bit sequence corresponding to one of the second subset of the decoding paths based at part on error detection bits and the generated path metrics. The wireless device may process the information bits based on a result of the decoding.
1. A method for wireless communication, comprising:
allocating a first subset of sub-channels of a polar code to a plurality of information bits, a second subset of the sub-channels to a plurality of bits associated with error detection and false alarm rate suppression, a third subset of the sub-channels to a plurality of frozen bits, and a fourth subset of the sub-channels to a plurality of dynamic frozen bits based at least in part on a reliability of each of the sub-channels, the plurality of dynamic frozen bits comprising a plurality of parity check bits;
generating the plurality of parity check bits based at least in part on a decoding/encoding order of the sub-channels of the polar code;
generating a codeword that is encoded using the polar code based at least in part on loading the plurality of information bits, the plurality of bits, the plurality of frozen bits, and the plurality of parity check bits into the sub-channels of the polar code; and
transmitting the codeword.
2. The method of claim 1 , wherein a number of the plurality of parity check bits is based at least in part on enabling early termination during parity-directed successive cancellation list (SCL) decoding.
3. The method of claim 1 , wherein a number of the plurality of bits associated with error detection and false alarm rate suppression is based at least in part on a defined detection rate.
4. The method of claim 1 , wherein allocating sub-channels of the polar code comprises:
identifying the third subset of the sub-channels for the frozen bits; and
allocating the fourth subset of the sub-channels to the plurality of parity check bits, the fourth subset of the sub-channels having a higher reliability than the third subset of the sub-channels, wherein the third subset of the sub-channels is identified based at least in part on a reliability metric.
5. The method of claim 1 , wherein the plurality of information bits and the plurality of bits associated with error detection and false alarm rate suppression are allocated to sub-channels having higher reliability than sub-channels allocated to the plurality of parity check bits.
6. The method of claim 1 , further comprising:
applying an error detecting algorithm to the plurality of information bits to generate the plurality of bits associated with error detection and false alarm rate suppression.
7. The method of claim 6 , wherein the error detecting algorithm is a cyclic redundancy check (CRC) algorithm.
8. The method of claim 1 , wherein generating the codeword comprises:
generating the codeword by applying a Boolean function to one or more of the plurality of information bits.
9. The method of claim 8 , wherein applying the Boolean function to the plurality of information bits comprises:
applying the Boolean function to each of the plurality of information bits prior to a sub-channel corresponding to each of the plurality of parity check bits according to the decoding/encoding order.
10. The method of claim 8 , wherein applying the Boolean function to the plurality of information bits comprises:
applying the Boolean function to the plurality of information bits prior to a first sub-channel corresponding to each of the plurality of parity check bits and subsequent to a second sub-channel corresponding to a previous parity check bit according to the decoding/encoding order.
11. The method of claim 8 , wherein a number of the plurality of parity check bits is three (3).
12. An apparatus for wireless communication, comprising:
a processor;
memory coupled with the processor; and
instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to:
allocate a first subset of sub-channels of a polar code to a plurality of information bits, a second subset of the sub-channels to a plurality of bits associated with error detection and false alarm rate suppression, a third subset of the sub-channels to a plurality of frozen bits, and a fourth subset of the sub-channels to a plurality of dynamic frozen bits based at least in part on a reliability of each of the sub-channels, the plurality of dynamic frozen bits comprising a plurality of parity check bits;
generated the plurality of parity check bits based at least in part on a decoding/encoding order of the sub-channels of the polar code;
generate a codeword that is encoded using the polar code based at least in part on loading the plurality of information bits, the plurality of bits, the plurality of frozen bits, and the plurality of parity check bits into the sub-channels of the polar code; and
transmit the codeword.
13. The apparatus of claim 12 , wherein a number of the plurality of bits parity check bits is based at least in part on enabling early termination during parity-directed successive cancellation list (SCL) decoding.
14. The apparatus of claim 12 , wherein a number of the plurality of bits associated with error detection and false alarm rate suppression is based at least in part on a defined detection rate.
15. The apparatus of claim 12 , wherein the instructions to allocate sub-channels of the polar code are further executable by the processor to:
identify the third subset of the sub-channels for the plurality of frozen bits; and
allocate the fourth subset of the sub-channels to the plurality of parity check bits, the fourth subset of the sub-channels having a higher reliability than the third subset of the sub-channels, wherein the third subset of the sub-channels is identified based at least in part on a reliability metric.
16. The apparatus of claim 12 , wherein the plurality of information bits and the plurality of bits associated with error detection and false alarm rate suppression are allocated to sub-channels having higher reliability than sub-channels allocated to the plurality of parity check bits.
17. The apparatus of claim 12 , wherein the instructions are further executable by the processor to:
apply an error detecting algorithm to the plurality of information bits to generate the plurality of bits associated with error detection and false alarm rate suppression.
18. The apparatus of claim 17 , wherein the error detecting algorithm is a cyclic redundancy check (CRC) algorithm.
19. The apparatus of claim 12 , wherein the instructions to generate the codeword are executable by the processor to:
generate the codeword by applying a Boolean function to one or more of the plurality of information bits.
20. An apparatus for wireless communication, comprising:
means for allocating a first subset of sub-channels of a polar code to a plurality of information bits, a second subset of the sub-channels to a plurality of bits associated with error detection and false alarm rate suppression, a third subset of the sub-channels to a plurality of frozen bits, and a fourth subset of the sub-channels to a plurality of dynamic frozen bits based at least in part on a reliability of each of the sub-channels, the plurality of dynamic frozen bits comprising a plurality of parity check bits;
means for generating the plurality of parity check bits based at least in part on a decoding/encoding order of the sub-channels of the polar code;
means for generating a codeword that is encoded using the polar code based at least in part on loading the plurality of information bits, the plurality of bits, the plurality of frozen bits, and the plurality of parity check bits into the sub-channels of the polar code; and
means for transmitting the codeword.
21. A non-transitory computer readable medium storing code for wireless communication, the code comprising instructions executable by a processor to:
allocate a first subset of sub-channels of a polar code to a plurality of information bits, a second subset of the sub-channels to a plurality of bits associated with error detection and false alarm rate suppression, a third subset of the sub-channels to a plurality of frozen bits, and a fourth subset of the sub-channels to a plurality of dynamic frozen bits based at least in part on a reliability of each of the sub-channels, the plurality of dynamic frozen bits comprising a plurality of parity check bits;
generate the plurality of parity check bits based at least in part on a decoding/encoding order of the sub-channels of the polar code;
generate a codeword that is encoded using the polar code based at least in part on loading the plurality of information bits, the plurality of bits, the plurality of frozen bits, and the plurality of parity check bits into the sub-channels of the polar code; and
transmit the codeword.