Bit-reliability mapping in LDPC-coded modulation systems

In this paper, we propose a reliability-based mapping strategy in LDPC-coded modulation systems. Compared to conventional mapping methods, this strategy gives a 0.15 dB - 0.2 dB performance improvement with no added complexity. Extrinsic information transfer (EXIT) chart analyses are used to explain the reason for this improvement. LDPC-coded modulation systems with gray and natural labeling are studied. We show that the performances of gray-labeled systems are always superior.