LDPC coded modulation for Rayleigh fading channels

This paper presents a novel scheme of low-density-parity-check (LDPC) coded modulation system called bit-expand-interleaved coded modulation with iterative decoding and demapping (BEICM-ID) over Rayleigh fading channels. In traditional bit-interleaved coded modulation (BICM) schemes and its iterative version, BICM-ID, each bit node is mapped into one single symbol, but in our new BEICM-ID scheme some bit nodes may map into multi symbols, thus diversity is achieved, and since iterative decoding and demapping is used, more mutual information will exchange among bit nodes, check nodes and symbol nodes which may further improve the total error correcting ability. Compared to the BICM and BICM-ID schemes, the proposed coded modulation scheme can achieve a performance gain with different modulation types under Rayleigh fading channels, with 256qam modulation the gain over BICM is about 1.5dB and the gain over BICM-ID is about 0.75dB.