Towards high performance short polar codes: Concatenated with the spinal codes

As the first ever provably capacity achieving codes, Polar codes have drawn a wide range of research interests in recent years. It is well known that short/finite-length Polar codes have relatively not so good bit error rate (BER) performance as the state-of-the-art channel codes (e.g. Turbo codes, LDPC). One commonly used way to improve the performance of short Polar codes is to concatenate the Polar codes with outer codes, but the amount of improvement is largely constrained by the performance of the outer codes with short codeword length. Motivated by this, in this work, we propose to use the newly invented Spinal codes, which has high performance with short code length, as the outer codes. Specifically, the designed codes, named as Spinal-Polar, is implemented through an interleaved concatenation scheme. In addition, we propose a joint iterative decoding algorithm for SpinalPolar, and the decoding complexity is analyzed theoretically. Extensive simulations are carried out, and results show that the proposed concatenation scheme can significantly improve the BER performance of short Polar codes.