Optimization of Vertical Handoff Decision Algorithm for Wireless Networks

Abstract

To provide mobile users with seamless access anywhere and anytime there is a strong need forinterworking mechanism between cellular networks and wireless local area networks in the next generation wirelessnetworks. Due to the heterogeneous underlying Quality of Service (QoS) support, the admission traffic in these areashas significant impact on overall resource utilization efficiency and QoS satisfaction when multiple services areconsidered. This paper addresses a Call-Level quality of Service (CLS) vertical handoff algorithm between WLANand cellular networks for seamless ubiquitous access. The CLS involves call blocking/dropping probabilities, meandata transfer rate, and number of handoff per call. Based on the above proposed admission strategy, the admissionregion of a cell or WLAN for the traffic can be derived with the function of new call arrival rate, handoff callarrival rate, and the radius of WLANs. The blocking and dropping probabilities are calculated under the guardchanneladmission strategy. The radius of WLAN is determined by using Simulated Annealing (SA) method to minimizethe cost function. Moreover, handoff traffic should be differentiated from new traffic in terms of call admission. When a Mobile Node (MN) moves from an area, with only cellular coverage to an overlaid WLAN area, theongoing call of the MN should be handed over to the WLAN, and handoff from WLAN to cellular network if theyleave the scope. The results based on a detailed performance evaluation study are presented here to demonstrate theefficacy of the proposed algorithm.