Optimization of symbol mapping for bit-intreleaved coded modulation with iterative decoding

Bit-interleaved coded modulation with iterative decoding (BICM-ID), which can improve the BER performance within limited bandwidth, is getting growing international attention. Symbol mapping, defined by the signal constellation and the bit labeling is the crucial design parameter to achieve a high coding gain for BICM-ID. It has been found that BICM-ID can yield a better coding gain by taking full advantage of the signal constellation. In this paper, an improved symbol mapping scheme, the combination of two QPSK with different radius and phases, called Cross Equalization-8PSK-Quasi-MSP (CE-8PSK) is proposed for BICM-ID. Simulation results show that, under the premise of same average power, the proposed scheme can improve the receiving performance of BICM-ID compared with the conventional symbol mapping schemes. At BER = 10^-4, the improved scheme can achieve more than 0.4 dB code gains over Rayleigh fading channels.