Suboptimum Multiuser Receivers for Coded IDMA Systems

Conventional receiver structures of coded IDMA systems consist of an elementary signal estimator (ESE) and K soft-in soft-out (SISO) decoders, which will bring high complexity to the systems. In this paper, we propose two relatively simple structures to combine decoding and multiuser detection (MUD). The first approach is partitioned approach that treats the MUD and decoding separately. The second approach is the harddecision combined approach that combines the MUD and harddecision decoding. We discuss the advantages and disadvantages of each approach. The numerical results show that the integrated approach even outperforms than the conventional receiver when the number of users is small (K <;8). Partitioned approach can achieve good performance as the conventional receiver performs.