An improved algorithm of MMSE multiuser detection for CDMA systems

Reducing the computational complexity of MMSE multiuser detection algorithms is the key to put them into practice for CDMA systems. In this paper, we studied the MMSE optimization criterion and the convergence characteristics of various iterative techniques in detail. We also analyzed the gradient projection algorithm and the algorithm of steepest descent to implement MMSE multiuser detection. Then we proposed an improved algorithm of steepest descent with noisy gradient. The algorithm uses time-varying step iteration to avoid the complex inverse operation of correlation matrices and the low convergence speed in traditional MMSE algorithms. The simulation results show that the algorithm can offer stable convergence and good detection performance.