A Comparative Study on Low-Cost Multiuser Detectors

In this paper, we compare different low-cost detection techniques for multiple access systems. The per-user complexities of these techniques are independent of the number of users. We demonstrate that the chip extrinsic information (CEI) method achieves the best performance, and the a posteriori probability information (APPI) and bit extrinsic information (BEI) methods provide different tradeoffs between performance, complexity and storage requirements. These low-cost multiuser detectors are applicable to a variety of systems, including interleave-division multiple-access (IDMA) and code-division multiple-access (CDMA) systems. Both analysis and simulation demonstrate that interleaving can greatly improve the effectiveness of the low-cost algorithms. In the presence of chip interleavers, the CEI method slightly outperforms the more complex minimum mean square error (MMSE) method.