Enhanced polar code constructions by strategic placement of CRC bits
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.
1. A method of wireless communications, comprising:
generating a codeword by encoding a sequence of information bits based on a polar code, wherein generating the codeword comprises:
determining a plurality of locations within the polar code having a rate of 1;
generating error detection codes based on portions of the sequence of information bits, the portions being defined by the plurality of locations within the polar code having a rate of 1;
inserting the error detection codes in the sequence of information bits at locations corresponding to the plurality of locations within the polar code having a rate of 1; and
generating the codeword based on the sequence of information bits, including the error detection codes, and the polar code; and
transmitting the codeword over a wireless channel.
2. The method of claim 1 , wherein the error detection codes comprise cyclic redundancy check (CRC) information.
3. The method of claim 2 , wherein generating the error detection codes comprises generating the error detection codes from preset subsets of the information bits, wherein each subset has a same number of information bits.
4. The method of claim 1 , wherein the polar code is of length N and further comprising:
encoding the information bits using a first polar code of length K to obtain bits for transmission via M virtual channels; and
further encoding the bits in each of the M virtual channels using a second polar code of length M, wherein N=K×M.
5. The method of claim 4 , wherein generating the error detection codes comprises generating the error detection codes for at least one of:
bits of one or more of the M virtual channels encoded with the second polar code, wherein the second polar code has a rate less than 1; or
bits of one or more of the M virtual channels encoded with the second polar code, wherein the second polar code has a rate of 1.
6. The method of claim 1 , further comprising inserting into the codeword one or more codes indicating how to decode 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.
7. A method of wireless communications, comprising:
generating a codeword by encoding a sequence of information bits based on a polar code, wherein generating the codeword comprises:
determining a plurality of locations within the polar code where a correct decoding path falls off a decoding list associated with the polar code;
generating error detection codes based on portions of the sequence of information bits, the portions being defined by the plurality of locations;
inserting the error detection codes in the sequence of information bits corresponding to the determined plurality of locations in the polar code; and
generating the codeword based on the sequence of information bits, including the error detection codes, and the polar code; and
transmitting the codeword over a wireless channel.
8. The method of claim 7 , wherein the error detection codes comprise one or more parity bits.
9. The method of claim 7 , wherein the polar code is of length N and further comprising:
encoding the information bits using a first polar code of length K to obtain bits for transmission via M virtual channels; and
further encoding the bits in each of the M virtual channels using a second polar code of length M, wherein N=K×M.
10. The method of claim 9 , wherein generating the error detection codes comprises generating the error detection codes for at least one of:
bits of one or more the M virtual channels encoded with the second polar code, wherein the second polar code has a rate less than 1; or
bits of one or more the M virtual channels encoded with the second polar code, wherein the second polar code has a rate of 1.
11. The method of claim 7 , further comprising inserting into the codeword one or more codes indicating how to decode 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.
12. The method of claim 7 , further comprising determining the locations of where a correct decoding path falls off a decoding list associated with the polar code based, at least in part, on one or more decoding parameters.
13. The method of claim 12 , 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.