Experimental analysis of horizontal and vertical handovers in wireless access networks using NS2

In broadband wireless access network, continuous high speed data communication can be provided to mobile subscribers by well designed mobility management, where handover is a key element in maintaining air link to base station even in high velocity. When a mobile station changes its geographical position, it may also need to change its attachment point in the network in order to retain the quality of the connection. Currently, the mobility of a terminal is a requirement of great importance, supported by a procedure known as handover. Horizontal Handover (HHO) is a symmetric process and happens within the same technology e.g between different Wifi cells. If it is executed between different technologies, for example, WiMAX to Wi-Fi, then it is called vertical HO. In this paper, initially we have investigated the performance of horizontal handovers within Wifi cells and then that of vertical handover between Wi-Fi and WiMAX. Evaluation of packet loss is done while transferring constant bit rate traffic (CBR) for UDP protocol This experiment can be used for academic purpose to help students understand the concept of handover.