Iterative demodulation and decoding of polar coded BICM with bit-flipping

Abstract

A new bit-interleaved coded modulation with iterative decoding (BICM-ID) scheme for polar codes is proposed, in which a flipping-based successive cancellation list (SCL) decoder is employed. This enhanced decoder can provide a large number of hard-decision outputs, from which only a few paths are selected and re-encoded to obtain a candidate set. Combined with the received signals and Pyndiah’s approximation, the candidate set generates extrinsic information which will be transmitted to the demodulator as the priori information after being interleaved. With the iterative decoding, the error performance of polar coded BICM scheme can be significantly improved. Simulation results show that the proposed flipping-based SCL decoder not only performs much better than the conventional SCL decoder with the same list size, but also shows competitiveness with some existing improved approaches of SCL decoding. More importantly, it generates efficient soft information which greatly improve the performance after iterative demodulation and decoding. Furthermore, the average complexity of the proposed BICM-ID scheme is acceptable and is similar to an SCL decoder at medium to high signal to noise ratio (SNR).