Constraint estimation for RSSI based handoff between UMTS and WLAN

In today´s age of internet we have worldwide diversified overlap network where Vertical Handoff (VHO) is a necessity. Mobile user is looking for Always Best Connected (ABC) strategy in the presence of multiple access technology. In this work the worst case scenario of handoff process in heterogeneous network is investigated through simulation. The available time for performing the handoff operation plays a crucial role especially in heterogeneous networks. The constraint involved is measured in terms of the maximum available time for mobile user with different speed. Both Outdoor to Indoor and Pedestrian test environment and Vehicular test environment scenario is adopted along with one transmitting node as Wi-Fi and the other node as UMTS. COST-231 Hata model and 3GPP (TR 101 112 V 3.1.0) specified models are used for WLAN and UMTS path loss models respectively. The handoff process is triggered based on the received signal power level as compared to the fade margin. Fade margin gives a probabilistic measure of the reliability of the communication link.