Abstract
Next generation wireless networks (NGWNs) will utilize several different radio access technologies, seamlessly integrated to form one access network. This network has the potential to provide many of the requirements that other previous systems did not achieve such as high data transfer rates, effectives user control, seamless mobility, and others which will potentially change the way users utilize mobile devices. NGWN will integrate a multitude of different heterogeneous networks including (a) cellular networks, passed through multiple generations-1G, 2G, 3G, and 3.5G; (b) wireless LANs, championed by the IEEE 802.11 wireless fidelity (WiFi) networks; and (c) broadband wireless access networks (IEEE 802.16, WiMAX). In this paper, a new adaptive quality of service (QoS) oriented CAC scheme is proposed to limit the occurrence of hard IEEE 802.11 WLAN-UMTS handovers to mobile users using real time (RT) applications. This scheme is hybrid, based on the service class differentiation, the location in the heterogeneous infrastructure and a vertical handoff decision function as well. Simulation results show that our policy achieves significant performance gains. It maximizes the utilization of the resources available at the WLAN cells, and meets as much as possible the QoS requirement of higher priority users. Copyright (C) 2008 John Wiley & Sons, Ltd.