Interference rejection and equalization for DS/CDMA multiuser communication

In direct-sequence code division multiple access (DS/CDMA) mobile communication systems with time-varying multipath channels, both intersymbol interference (ISI) and multiple-access interference (MAI) must be considered. It has been shown that iterative equalization and decoding method is an efficient technique to combat ISI. Based on this approach, we propose a turbo equalization-like receiver for multiuser DS/CDMA systems in multipath channels. The proposed MAI-rejection/ISI suppression filter is based on a cost function evaluated at the PN code despreader's and data detector's output. Besides, our scheme does not require a training signal. Simulation results show that the proposed iterative receiver performs better than that of non-iterative scheme, and the BER decreases with the number of iteration increases.