SUMMARYThe goal of the network mobility management is to effectively reduce the complexity of handoff procedure and keep mobile devices connecting to the Internet. When users are going to leave an old subnet and enter a new subnet, the handoff procedure is executed on the mobile device, and it may break off the real-time service, such as VoIP or mobile TV, because of the mobility of mobile devices. Because a vehicle is moving so fast, it may cause the handoff and packet loss problems. Both of the problems will lower down the throughput of the network. To overcome these problems, we propose a novel network mobility protocol for vehicular ad hoc networks. In a highway, because every car is moving in a fixed direction at a high speed, a car adopting our protocol can acquire an IP address from the vehicular ad hoc network through the vehicle-to-vehicle communications. The vehicle can rely on the assistance of a front vehicle to execute the prehandoff procedure, or it may acquire a new IP address through multihop relays from the car on the lanes of the same or opposite direction and thus may reduce the handoff delay and maintain the connectivity to the Internet. Simulation results have shown that the proposed scheme is able to reduce both the handoff delay and packet loss rate.