Low complexity variable step size mechanisms for constrained minimum variance CDMA receivers

In this work we investigate the performance of blind adaptive receivers for direct sequence code division multiple access (DS-CDMA) systems that employ stochastic gradient (SG) algorithms with variable step size mechanisms. Two low complexity variable step size mechanisms are proposed for constrained minimum variance (CMV) receivers that operate with SG algorithms and are also incorporated in the channel estimation algorithms. We examine the proposed adaptation techniques and compare them with recently reported approaches in frequency selective fading channels and nonstationary environments. Simulation experiments in a number of scenarios show that, although less complex, the proposed mechanisms for DS-CDMA receivers are superior to recently reported methods.