Repeat accumulate coded modulation with partial iterative demapping

Repeat accumulate (RA) codes are the known simplest one among the family of the capacity-approaching codes. It is much simpler than turbo codes and low density parity check (LDPC) codes, and hence is a competitive choice for the applications of B3G/3G or 4G systems. The main drawback of RA codes, the low code rate, can be overcome by concatenating modulations. In this paper, performance of RA coded demapping (RACM-ID) and referred to as RA coded modulation with partial iterative demapping (RACM-PID) is proposed. The algorithm is equivalent to reduce the degree of the modulation nodes, which is the most calculation cost in the Tanner graph, and thus we have reduced a large part of the calculation complexity of iterative demapping (ID) while keeping the most of the performance gain due to ID. Simulation results are presented for 8PSK and 16QAM examples.