A hybrid multi-user detector for CDMA

A hybrid multi-user detector for code division multiple access (CDMA) based on stochastic Hopfield neural network (SHNN) and reduced detector (RD) is presented in this paper. Its purpose is to give an insight to the problems of CDMA and to propose novel algorithms for multi-user detection (MUD). An investigation on the nature of the local minima of the optimal multi-user detector´s (OMD) objective function leads to the development of an efficient algorithm that can reduce significantly the size of the OMD optimization problem and seems to have a superior performance. Because the RD is based on digital signal processing (DSP) and SHNN is based on discrete Hopfield neural network (DHNN), the hybrid detector is a digital processing scheme which can be realized with the development of DSP. The performance of the hybrid detector is evaluated via simulations and it is shown to exceed that of other sub optimal receivers at a much lower computational cost in CDMA transmission case.