Performance evaluation of connection admission control for W-CDMA networks using dynamic system simulations

Connection admission control (CAC) is an essential technical for code-division multiple-access (CDMA) mobile cellular communication systems. It has a strong impact on the system quality and capacity. In this paper, we investigate the UMTS wideband CDMA technology and focus on the impact of the CAC algorithms with respect to the overall network performance. Of particular interest within this context is the choice of a suitable admission criterion, i.e. when to admit or deny new service requests. For the investigations, we use a dynamic network simulation tool named STEAM (simulation tool for the evaluation of algorithms in mobile networks). The investigations on CAC reveal that e.g. by setting the admission threshold there is a trade-off between blocking and dropping of users: when increasing the threshold the blocking rate decreases while the dropping rate increases and vice versa. Hence, the operator is able to adjust the network quality in terms of blocking and dropping by setting control parameters and thresholds. In this contribution, we show the impact of these parameters and give practical design rules for network operations. By using the proposed control algorithm, it is possible to achieve high system capacities while the system load is still well controlled.