Vertical handoff modeling and simulation in VANET scenarios

In Vehicular ad hoc network (VANET), vehicular users (VUs) are capable of connecting to different access networks for interacting both safety related information and user application related information. In the overlapped area of heterogeneous networks, VUs are allowed to perform vertical handoff between various access networks. As the performance of vertical handoff plays an important role in guaranteeing user quality of service (QoS) and achieving system performance enhancement, it should be examined and evaluated thoroughly. In this paper, vertical handoff performance of VUs in a VANET scenario consisting of heterogeneously integrated universal mobile telecommunications system (UMTS) and wireless local area network (WLAN) is evaluated based on network simulator 2 (NS2). Multi-mode nodes, which are capable of accessing both networks and a media independent handover (MIH)-based vertical handoff scheme are implemented in NS2. The impacts of user velocity, the strength of traffic load and the type of handoff mechanisms on the communication performance of VUs, i.e., throughput, handoff latency and packet loss are examined.