Power control and space-time diversity for CDMA systems

Space-time diversity systems jointly with power control are proposed for uplink and downlink in CDMA systems. It is assumed that antenna arrays are deployed at base stations and omnidirectional antennas are used at mobiles. In uplink, the optimal combining weight vectors at RAKE receivers and mobile power allocations are calculated jointly, such that the signal to interference and noise ratio (SINR) at each base station is above a threshold, and mobile transmitted power is minimized. In downlink, transmit beamforming vectors are calculated to minimize the total transmit power and to set the SINR at each mobile to a target value. Further, an algorithm is proposed which maximizes the minimum SINR in a network. A system is considered where base stations use multibranch transmit diversity systems and mobiles use RAKE receivers. A scheme is proposed to jointly calculate the transmit space-time vectors and receiver optimum combining weight vectors such that the SINR requirement at each link is satisfied