Repeat Accumulate Codes for Bit-Interleaved Coded Modulation with Iterative Demapping

Repeat accumulate (RA) codes combine both the advantages of turbo codes and low-density parity-check (LDPC) codes by having low encoding complexity of turbo codes with low decoding complexity of LDPC codes. The RA interleaver is chosen by random construction using the bit-filling method. In this paper, we investigate the performance of bit interleaved coded modulation (BICM) with iterative decoding for bandwidth-efficient transmission. The performance of BICM with iterative decoding and demapping (BICM-ID) is also investigated. The choice of channel code and signal constellation mapping is selected for achieving close to optimum performance. Both BICM and BICM-ID systems using systematic RA codes with Gray labelling on an AWGN channel are considered. Simulation results are presented for 16-QAM examples for rates ¿ and ¿.