A Vertical Handoff Decision Algorithm (VHDA) and a Call Admission Control (CAC) policy in integrated network between WiMax and UMTS

In this paper, we propose to provide ubiquitous access anywhere anytime by covering the remote areas using World Interoperability for microwave access (WiMax), complementing the existing universal mobile telecommunications systems (UMTS). In this proposed system to integrate WiMAX and UMTS, certain areas are covered by both systems. The overlapping areas are modeled as WiMAX cells overlaid with UMTS cells due to the bigger coverage of WiMAX. In order to facilitate the interworking communications between two different systems, we design and develop vertical handoff algorithm and call admission control policy for the interworking system in the overlaid service areas, taking into consideration of the quality of service (QoS), the cost of handoff and other parameters. Typical QoS parameters maybe load balancing, handoff latency, packet loss ratio (PLR) and transmission rates. For the cost of handoff, we consider the mobile velocity, power consumption, available bandwidth, etc. The call admission control (CAC) scheme mainly depends on the wideband power, throughput and the priority of new arrival calls and handoff calls.