Optimized symbol mapping for bit-interleaved coded modulation with iterative decoding

Symbol mapping is very crucial for the performance of bit-interleaved coded modulation with iterative decoding (BICM-ID). In this paper, a new scheme of symbol mapping called Cross-8PSK-Quasi-Gray is proposed. The optimization scheme of Cross-8PSK is composed of two QPSK with different radius and phases. Through analysis and comparisons with three previously mentioned symbol mappings in terms of channel capacity and error performance, simulation results show that Cross-8PSK-Quasi-Gray mapping significantly outperforms set partitioning, semi set partitioning labeling maps in the aspects of both channel capacity and error performance. The overall performance of Cross-8PSK-Quasi-Gray mapping is nearly close to gray mapping in conventional 8PSK. Thus, Cross-8PSK-Quasi-Gray mapping is a good scheme for designing the power-efficient BICM.