A distance-based event-driven broadcast (DEB) mechanism for V2V safety communications

Broadcasting in vehicular ad hoc networks (VANETs) is the ideal communication technique for information dissemination and is conventionally defined in IEEE 802.11p-based wireless access in vehicular environments (WAVE). Vehicular systems present a unique characteristic of dynamic positions and varying vehicle density due to motion which is a challenge in communication systems. Since the node density is a critical performance parameter in broadcast communications, there is need to offer media access control (MAC) solutions to the broadcast storm problem which exists in high density vehicular domains. This paper proposes the use of a pilot beacon message broadcast from an emergency vehicle and then selects vehicles receiving the pilot message beyond a given distance to follow an event-driven transmission approach. The event in this case is the reception of a message with in a determined distance and the response being a single message transmission. The other vehicles which are not selected and do not participate in the event driven approach use the conventional IEEE 802.11p broadcast style. The main goal of the study is to improve on the reliability of vehicle to vehicle safety message communications. Computer simulations show that the packet delivery ratio and end to end delay for the proposed approach is better than the conventional IEEE 802.11p broadcast approach.