Design and analysis of an adaptive guard channel based CAC scheme in a 3G-WLAN integrated network

In wireless networks, guard channel based Call Admission Control (CAC) schemes are widely used to protect handoff calls for seamless wireless services. However, the introduction of guard channels in wireless networks results in the increase in the new call blocking probability. This general situation also occurs in a 3G-WLAN integrated network. To solve this problem in a 3G-WLAN integrated network for QoS support, we propose an adaptive guard channel based CAC scheme in this paper. The main objective of our guard channel based CAC scheme is to alleviate the increase in the new call blocking probability due to guard channels while it can still protect handoff calls. For the design of our adaptive guard channel based CAC scheme, we first develop and analyze a performance model for a general guard channel based CAC scheme based on a level-dependent quasi birth and death model. The analytic results are used to design our adaptive guard channel based CAC scheme. Numerical studies show that our adaptive guard channel based CAC scheme can achieve its objective and its performance is near optimal.