Aspects of this disclosure provide a technique for implementing polar encoding with incremental redundancy HARQ re-transmission. In particular, a transmitter encodes a message using different polar codes to obtain a first codeword and a second codeword that is twice the length of the first codeword, and transmit the first codeword as an original transmission, and the second half of the second codeword as a re-transmission without transmitting the first half of the second codeword. Information bits that are common to both the first codeword and the second half of the second codeword is mapped to more-reliable bit-locations in the second half of the second codeword. Decoded bit values for the common information in the original transmission and retransmission is compared by the receiver to perform a parity check.