A hybrid digital signal processing-neural network CDMA multiuser detection scheme

We present a new hybrid digital signal processing-neural network two-step multiuser detection scheme whose small computational complexity makes it attractive for real-time CDMA multiuser detection. An investigation on the nature of the local minima of the Optimal Multiuser Detector's (OMD) objective function leads to the development of an efficient algorithmic stage that can reduce significantly the size of the OMD optimization problem. This stage may then be followed by a Hopfield neural network employed to solve a smaller size residual problem of the same form. The performance of the hybrid detector is evaluated via simulations and it is shown to exceed that of other suboptimal receivers at a much lower computational cost in both synchronous and asynchronous CDMA transmission cases.