A Comparison of Concatenated Polar Codes with Different Interleaving and Decoding Schemes

Towards the 5th generation wireless systems (5G) and beyond, polar codes have become a hot research topic in the field of communications. In our work, concatenated polar codes with different interleaving and decoding schemes are designed to improve the error performance of finite-length polar codes. In this paper, concatenated polar codes with outer BCH codes are first constructed, besides, concatenated LDPC codes and concatenated Turbo codes are also designed for comparison. At the same time, random interleaving (RI) scheme and blind interleaving (BI) scheme are proposed to construct the concatenated codes. From the simulation results of this paper, we can see that the bit error rate (BER) performance of concatenated codes using BI scheme is better than that of concatenated codes using RI scheme. Furthermore, the BER performance of concatenated polar codes outperforms that of concatenated LDPC codes, but not as good as that of concatenated Turbo codes. To improve the BER performance of concatenated polar codes, we adopt the CRC Aided Successive Cancellation List (CA-SCL) decoding scheme instead of the Successive Cancellation (SC) decoding scheme for inner polar decoding. The results of our study indicate that the BER performance of concatenated polar codes with CA-SCL outperforms that of concatenated polar codes with SC. In addition to this, with the same CRC code length, increasing the list size can improve the decoding performance of CA-SCL. However, there is also a bad side: the decoding complexity of CA-SCL increases rapidly as the list size increases. On the other hand, with the same list size, increasing the CRC code length adversely deteriorates the decoding performance of CA-SCL.