An optimized symbol mapping of 8PSK modulation for BICM-ID in low SNR

An optimized symbol mapping of 8PSK modulation is proposed for bit interleaved coded modulation with iteratively decoding (BICM-ID). The new scheme which uses the average near neighbor hamming distance in the constellation as design criterion in low SNR is composed two QPSK with different radius and phases. It reduces the average near neighbor hamming distance in the constellation by way of adjusting the size of radius. Analysis and simulation results show that the proposed scheme achieves better performance than the convectional signal mapping for a BICM-ID system in low SNR.