Transmit beamforming and power control in downlink channels of a multi-rate CDMA communication system

This paper studies the benefits of combining beamforming and power control in the downlink channel of a CDMA communication system employing a variable length orthogonal spreading code (OLSC). It is demonstrated that the high data users cause significant interference to the low data users if we do not employ beamforming. Furthermore, if we perform beamforming for both types of users, most of the gain we achieve is due to the high data users if the total power of the high data users is much higher than that of the low rate users. Thus we may reduce the computational requirement significantly if we perform beamforming for the high data users only with a small increase in total power