Concatenated polar codes based on selective polarization

In this paper, we propose a selectively polarized concatenation structure for polar codes. We first divide the polarized bit-channels into three types, i.e., good, intermediate and bad bit-channels according to their Bhattacharyya parameter. Then, through combining several information blocks, the intermediate bit-channels are further polarized to enhance polarization rate. Theoretical and numerical results indicate that the proposed scheme achieves the same capacity as original polar codes at the same length, while the bit error rate (BER) performance is better than that of original polar codes as same decoding delay is considered. The polar codes can be used in the cognitive radio system.