Adaptive space-time full- and reduced-length MMSE receivers in asynchronous DS/CDMA

To improve the co-channel interference suppression capability of the existing single-antenna MMSE receivers in asynchronous DS/CDMA system, two adaptive space-time full-length and reduced-length MMSE receivers are proposed by combining an adaptive antenna array and adaptive filter to perform filtering in both the space and time domains. The convergence of the LMS and RLS adaptation procedures toward the corresponding Wiener optimum solutions of variable weights of the adaptive array and adaptive filter is presented based on minimisation of MSE. Simulation results show that considerable improvement in convergence, steady-state MSE and BER at low SNR can be achieved over the existing MMSE receivers.