Exploiting beacons for scalable broadcast data dissemination in VANETs.

ABSTRACTVehicular Ad-hoc Networks (VANETs) enable the timely broadcast dissemination of event-driven messages to interested vehicles. However, when dealing with broadcast communication, suppression techniques must be designed to prevent the so-called broadcast storm problem. Numerous suppression schemes aim to reduce broadcast redundancy by assigning vehicles to different delay values, i.e., time slots, that are inversely proportional to their distance to the sender. In this way, only the farthest vehicles would rebroadcast, thereby allowing for quick data dissemination. Despite many efforts, current delay-based schemes still suffer from high levels of contention and collision when the number of vehicles rebroadcasting nearly simultaneously is high in dense networks. Even choosing appropriate values for the total number of time slots does not prevent situations where simply no vehicle is assigned to the earliest time slot, what may result in high end-to-end delay. In this paper, we tackle such scalability issues with a scheme that controls with precision the density of vehicles within each time slot. To reach this goal, we exploit the presence of beacons, periodic messages meant to provide cooperative awareness in safety applications. Simulations results show that our protocol outperforms existing delay-based schemes and is able to disseminate data messages in a scalable, timely, and robust manner.