Medium Access Concept for VANETs Based on Clustering

Vehicle-to-vehicle communication is a promising technology for enhanced road safety as it provides the possibility to get a detailed knowledge about the traffic situation a long way ahead. Vehicles transmit information about nearby dangers like obstacles on the road as well as warning messages over long distances to all vehicles in a certain area. Therefore the dissemination of the data has to be done in broadcast transmission. This transmission concept causes severe problems regarding the organization of the medium access. The often used RTS/CTS mechanism is no longer feasible, which is especially problematic in road scenarios, where the hidden station problem is a major cause of data loss due to collisions. In addition the regarded data makes high demands on the provided quality of service. Especially reliability and delay are crucial for the efficiency of the warning system. In this paper we introduce a concept for a medium access control which minimizes the effects of the hidden station problem by introducing a clustering scheme. Therefore clusterheads among the vehicles are selected, which are then responsible for assigning bandwidth to the other vehicles in their clusters. This paper presents an algorithm for selecting the clusterheads along with a concept for assigning bandwidth to the nodes.