Non-uniform signal constellation for iteratively decoded bit interleaved coded modulation (BICM-ID) with convolution and LDPC codes

Bit interleaved coded modulation with iterative demapping and decoding (BICM-ID) is an effective technique to achieve high spectral efficiency with performance close to capacity limits. However, the use of non-uniform signal constellation following a Gaussian distribution instead of conventional equiprobable signaling provides a further improvement, i.e. shaping gain. In this paper, we investigate the effect of nonuniform constellation on the performance of BICM-ID systems with different forward error correction (FEC) coding schemes such as convolution code and low-density parity-check (LDPC) code as outer code. Simulation results show that the non-uniform constellations can offer a shaping gain up to 0.21 dB.