SmartGeocast: Dynamic abnormal traffic information dissemination to multiple regions in VANET

With the increase of vehicles in city, unexpected abnormal events may occur on roads more frequently. It is necessary to disseminate abnormal traffic information to other vehicles in vehicular ad hoc networks (VANETs).With traditional geocasting protocols, the considered target region is normally single and its range is fixed. However, when an abnormal event occurs, its impacted area may include multiple streets or roads and it may last for a long time. In this paper, for multiple target regions we propose a SmartGeocast information dissemination mechanism, which contains two procedures including geocasting initialization and geocasting maintenance. In the first procedure, the abnormal traffic information can be delivered to multiple regions quickly and efficiently through path sharing and path splitting schemes. Considering that new vehicles may continuously drive into the target regions, the abnormal traffic information have to be “floating or visible” to them until the event impact gradually disappears. In the second procedure, it divides a small area in each target region for information dissemination to new arrived vehicles repeatedly, so as to furthermore reduce the message redundancy and maintenance cost. Experimental results show that the proposed SmartGeocast protocol can decrease the probability of receiving the repeated messages while try to avoid missing the important information.