Speed adaptive probabilistic flooding for vehicular ad-hoc networks

A significant issue in vehicular ad hoc networks is the design of an effective broadcast scheme which can facilitate the fast and reliable dissemination of emergency warning messages in the vicinity of an expected event, such as a car accident. In this work we propose a novel solution to this problem, which we refer to as Speed Adaptive Probabilistic Flooding. The scheme employs probabilistic flooding to mitigate the effects of the broadcast storm problem, typical when using blind flooding, and its unique feature is that the rebroadcast probability is regulated adaptively based on the vehicle speed to account for varying traffic densities within the transportation network. The protocol enjoys a number of benefits relative to other approaches: it is simple to implement, it does not introduce additional communication burden, as it relies on local information only and it does not rely on the existence of a positioning system which may not always be available. The scheme is evaluated on different sections of the highway system in the City of Los Angeles using an integrated platform combining the OPNET Modeler and the VISSIM simulator. Simulation results indicate that the proposed scheme fulfills its design objectives as it achieves high reachability and low latency of message delivery in a number of scenarios. Its robustness with respect to changing number of hops and transmission ranges is also demonstrated.