Event suppression for safety message dissemination in VANETs

With recent advances in vehicular technology, a variety sensors, radars and onboard computing systems have enabled vehicles to become powerful information gathering and processing platforms. Sensors can continuously monitor and interpret the vehicle's local environment and quickly detect dangerous situations. As vehicles in close proximity detect the same dangerous situation they will inevitably broadcast messages relating to the same event. As all these vehicles report on the same event broadcasting leads to dramatically excessive message redundancy. In the paper we present the Event Suppression for Safety Message Dissemination (ESSMD) scheme that reduces the number of broadcasting vehicles reporting on the same event. This scheme was compared with existing aggregation strategies for safety-related message dissemination. Experimental results using the OPNET simulator demonstrate that ESSMD significantly reduces redundant data transmissions and does not add any extra end-to-end delay compared with existing aggregation strategies. However, ESSMD had a decreasing probability of event reception due to an unreliable broadcasting protocol. The reception rate was improved by the introduction of a scheme called ESSMD+Rep that increases the reliability of the broadcasting protocol by repeating broadcasts at the source vehicles.