Abstract: The combination of Ad hoc and heterogeneous network with infrastructure was proposed to alleviate network congestion. When the network was not congested, the vehicle terminal used utility function algorithm to select network between the base stations or the access points in order to complete the vertical handoff quickly. When the network was congested, firstly, the Ad hoc was divided into several clusters by clustering algorithm; then, the transition among vehicle states was carried out; finally, the access algorithm was selected according to the vehicle status. Simulation results show that the proposed algorithm reduces the probability of network congestion and improves the system throughput.

Key words: Ad hoc network, heterogeneous network, vertical handoff, cluster