An Efficient Emergency Message Dissemination Protocol in a Vehicular Ad Hoc Network

Dissemination of emergency messages is a critical research area which aims to avoid traffic fatalities. Due to inherent characteristics of vehicular ad hoc networks and the emergency of the messages, most of developed applications are based on the broadcasting messages. The most basic strategy is called flooding. This strategy is well studied in the context of mobile ad hoc networks and has been shown it causes contentions, collisions and redundancy, well known as the ‘broadcast storm problem’. The majority of existing solutions focuses on decreasing the number of relay nodes and discards the use of unicast messages. In this paper we study a new strategy that combines the use of unicast and broadcast modes at the same time. Simulation results show that the proposed protocol achieves low latency in delivering emergency warnings in spite of the use of unicast messages and these results can be enhanced by modifying the MAC layer protocol parameters.