Wavelet transform and genetic algorithm based multiuser detectors for asynchronous CDMA

New methods for implementation of wavelet transform based multiuser detector (WTMUD) and wavelet-transform-and-genetic-algorithm based multiuser detector (WTGAMUD) are proposed for asynchronous direct-sequence code division multiple access (DS-CDMA) systems, respectively. Firstly, WTMUD is proposed which can reduce the computation complexity of inverting the correlation matrix, and ensure the bit-by-bit detection of desired users. WTMUDs´ outperform their counterparts that do not incorporating wavelet transform on the aspects of BER performance, near-far resistance ability, and system capacity. Secondly, genetic algorithm (GA) is incorporated in WTMUD to further optimize its output, and so form the WTGAMUD. Simulation results show that WTGAMUDs´ with a medium population size can provide much better performance than WTMUDs´ after only 3 to 5 generations evolution.