A Reliable Broadcast Message Dissemination for VANETs via Rebroadcating

Broadcast is a typical message dissemination mechanism for various VANETs applications such as emergency notifications, traffic information, notice and advertisement messages, etc. The Contention-Based Forwarding (CBF) is one of the representative broadcast approaches for VANET, which may avoid the broadcast storm problem. Exploiting the geographical information of the vehicles, the CBF-based approach selects the sending vehicle which is farthest from the previous sender without the periodic beacon exchanges among the neighboring vehicles. It may, however. hinder the reliability of the message delivery in some cases. In this paper, we identify scenarios in which broadcast messages cannot be propagated on certain roads when the CBF-based approach is used. We, then, propose a more reliable broadcast message dissemination approach which ensures that at least one vehicle is selected as the sending vehicle for each road. We evaluate and compare the performance of our road-based broadcast message dissemination approach against the CBF-based approach and the basic flooding approach. We measure the reliability of message delivery, and the ratio of the relay vehicles to the number of vehicles which received the message. The results show that although the proposed approach is less efficient than CBF -based approach, it is almost as reliable as the basic flooding approach.