On downlink admission control with fixed multi-beam antennas for WCDMA system

Fixed multi-beam base stations can significantly increase the capacity of WCDMA systems. Previous capacity studies have not included important radio network algorithms (RNA) such as admission control (AC), which are essential to guarantee an acceptable quality of service (QoS). Some of these RNA may have to be changed to secure the full gains of fixed multi-beam antennas. In this paper two downlink AC strategies, beam AC and cell AC, are investigated by means of dynamic system simulations. Beam AC takes the spatial dimension into account by considering the load in each beam, whereas cell AC does not. The performance of the two AC strategies is compared in different user scenarios for a fixed multi-beam smart antenna concept. It is shown that beam AC ensures system stability and gives up to 30% more capacity than cell AC, when the traffic distribution is non-uniform.