Improved Vertical Handover Decision Algorithm for UMTS- WLAN

Next generation wireless systems consist of heterogeneous wireless networks. Wireless LAN (WLAN) and cellular mobile radio systems will be important part of heterogeneous networks. Universal mobile telecommunication system (UMTS) provides wide-area coverage, high mobility but relatively low data rate. WLAN is designed for low-range, high/medium data rate access, low mobility and can be used as a complement to larger cellular mobile radio systems. In this paper, we consider a simple heterogeneous system of WLAN and UMTS cell. Vertical handover plays a vital role in ensuring quality of service in heterogeneous networks. In this paper, we proposed a vertical handover algorithm for an integrated cellular/wireless LAN system. The design goal is to provide the user the best available quality of service (QoS) at any time. Moreover, connections are handed over independently between UMTS and WLAN, aiming at seamless service continuity. Here we have taken handover rate, probability of outage and probability of handover as the performance metrics. Simulation results show that adaptive vertical handover algorithm improves the performance.