Toward a New Broadcasting Protocol to Disseminate Safety Messages in VANET

Abstract

VANETs are a kind of MANETs, where vehicles communicate among themselves via a vehicle-to-vehicle (V2V) communication, or with other devices located on the roadsides (RSU: Roadside Unit) via vehicle-to-infrastructure (V2I) communication. Some devices called on-board units (OBUs) are installed in each vehicle, and work in ad-hoc mode, being able to broadcast data through multiple hops to improve the driver’s safety and the transportation efficiency. The fast actual trend of broadcasting protocols in VANET aims to provide additional comfort to the cars’ drivers and be notified about a critical incident in the road. Therefore, the design of a good broadcasting protocol that performs well in all the previous criteria to avoid storm problem remains the most paramount task. The main issue is how to maximize the reachability while minimizing the rebroadcasting and the end-to-end delay. In most of the previous works, they either maximize the reachability or minimize the end-to-end delay, but they do not do both jointly. We present in this paper a novel method to calculate the waiting time of the counter-based and probability-based schemes, based on the speed of the vehicle, to assess the congestion level of the network. Simulation results through NS2 using 802.11P show that the new method performs better under different mobility scenarios (Grid and highway Map).