A Multi-Hop Urban Broadcast Protocol for Vehicle-to-Vehicle Networks

Inter-Vehicle Communication Systems rely on multi-hop broad- cast to disseminate information to locations beyond the trans- mission range of individual nodes. Message dissemination is especially difficult in urban areas crowded with tall buildings because of the line-of-sight problem. In this paper, we pro- pose a new efficient IEEE 802.11 based multi-hop broadcast protocol (UMB) which is designed to address the broadcast storm, hidden node, and reliability problems of multi-hop broadcast in urban areas. This protocol assigns the duty of forwarding and acknowledging the broadcast packet to only one vehicle by dividing the road portion inside the trans- mission range into segments and choosing the vehicle in the furthest non-empty segment without apriori topology infor- mation. When there is an intersection in the path of the message dissemination, new directional broadcasts are initi- ated by the repeaters located at the intersections. We have shown through simulations that our protocol has a very high success rate and efficient channel utilization when compared with other flooding based protocols.