Systematic polar codes for rateless wireless communications

A method for wireless communication at a first wireless device, comprising:

• receiving, via a channel between the first wireless device and a second wireless device, a codeword associated with a plurality of information bits encoded according to a systematic polar code into a plurality of encoder output bits;
• obtaining a first plurality of log likelihood ratios (LLRs) associated with the plurality of encoder output bits based at least in part on performing a first decoding operation on the codeword using the systematic polar code;
• receiving, via the channel and based at least in part on a failure of the first wireless device to decode one or more information bits of the plurality of encoder output bits, a second plurality of LLRs corresponding to a subset of the plurality of encoder output bits, the second plurality of LLRs being received independent of the polar code, wherein an index associated with each information bit in the subset of the plurality of encoder output bits is identified based at least in part on an order of at least one of the first plurality of LLRs or the second plurality of LLRs;
• and
• performing, on the codeword, a second decoding operation using the systematic polar code and a combination of the first plurality of LLRs and the second plurality of LLRs.

An apparatus for wireless communication at a first wireless device, comprising:

• one or more processors;
• one or more memories coupled with the one or more processors;
• and
• instructions stored in the one or more memories and executable by the one or more processors individually or collectively to cause the apparatus to:
• transmit, via a channel between the first wireless device and a second wireless device, a codeword associated with a plurality of encoder input bits encoded using a systematic polar code, wherein the plurality of encoder input bits is associated with a plurality of information bits different from the plurality of encoder input bits;
• and
• transmit, via the channel, a subset of the plurality of encoder input bits based at least in part on identifying a failure of the second wireless device to decode one or more information bits of the plurality of information bits, wherein the subset of the plurality of encoder input bits are selected according to an order of log likelihood ratios (LLRs) associated with a plurality of bit-channels used for encoding the plurality of encoder input bits according to the systematic polar code.

An apparatus for wireless communication at a first wireless device, comprising:

• one or more processors;
• one or more memories coupled with the one or more processors;
• and
• instructions stored in the memory and executable by the one or more processors to cause the apparatus to:
• receive, via a channel between the first wireless device and a second wireless device, a codeword associated with a plurality of information bits encoded according to a systematic polar code into a plurality of encoder output bits;
• obtain a first plurality of log likelihood ratios (LLRs) associated with the plurality of encoder output bits based at least in part on performing a first decoding operation on the codeword using the systematic polar code;
• receive, via the channel and based at least in part on a failure of the first wireless device to decode one or more information bits of the plurality of encoder output bits, a second plurality of LLRs corresponding to a subset of the plurality of encoder output bits, the second plurality of LLRs being received independent of the polar code, wherein an index associated with each information bit in the subset of the plurality of encoder output bits is identified based at least in part on an order of at least one of the first plurality of LLRs or the second plurality of LLRs;
• and
• perform, on the codeword, a second decoding operation using the systematic polar code and a combination of the first plurality of LLRs and the second plurality of LLRs.