Improving the Error Coefficient of Polar Codes

Polar codes are normally constructed based on the reliability of the sub-channels in the polarized vector channel. Code construction based on reliability is compatible with successive cancellation decoding. However, due to poor Hamming distance properties, the designed codes cannot perform well with near maximum likelihood decoders. In this work, we propose a new approach that modifies polar codes and PAC codes to significantly lower the number of codewords with minimum distance (a.k.a. error coefficient). This approach is based on the recognition of all the rows of polar transform involved in the formation of the minimum-weight codewords. The numerical results show that the designed codes outperform polar codes and PAC codes under list decoding.