Reliable Protocols for Alert Message Delivery in Vehicular Wireless Networks

In vehicular networks, supporting safety application demands reliable alert message dissemination. In this paper, we focus on reliable alert message dissemination in vehicular wireless networks. In general, the flooding method can beeasily adopted to disseminate alert messages on highway. However, flooding may cause redundant alert messagesand lead to the broadcast storm problem. In this paper, we proposea fault-tolerant broadcasting protocol and the farthest node first protocol for disseminating the alert messages. The fault-tolerant broadcasting protocol designates two vehicles for reliability, while the farthest node first protocol adopts the distance formula for selecting the farthest vehicle in the transmission range of source vehicle as the relay vehicle. In addition, we propose an exponential back-off method that can effectively reduce the number of alert messages. Finally, we implement the proposed protocol in the NS-2 simulator. The simulation results show that the proposed protocol not only reduces the number of the alert messages but also decreases the transmission delay of the alert messages and increases the reliability of system.