Adaptive spatial and temporal correlation control in CDMA communication systems

Joint transmit beamforming, power control and the MMSE receiver are proposed for downlink channels of CDMA communication systems. Variability of the total transmit power while satisfying each user´s quality of service is studied. We show that the total transmit power has a significant variation when we consider the combination of MMSE receiver and power control. When transmit beamforming is added, such variation is reduced significantly and great transmit power saving is achieved through the proposed scheme. The signature diversity concept is revealed for joint transmit beamforming and the MMSE receiver. An optimum MMSE, transmit beamforming and adaptive frequency hopping scheme is proposed to maximize the benefits of the MMSE receiver and transmit beamforming. Two sub-optimal algorithms are proposed to solve the optimization problem with reduced computational requirements