microSlotted 1-Persistence Flooding in VANETs

Many Driver Support Systems in future vehicles will rely on wireless communication. This wireless communication can be divided into two categories: Vehicle-toVehicle (V2V) and Vehicle-to-Infrastructure (V2I). V2V is often used for vehicles to exchange information of a local nature, e.g. co-operative following or collision avoidance. V2I can be used as ’smart road signs’, access to back-end networks (e.g. Internet) or as simple repeaters. The term VANET is key to V2V and V2I communication: Vehicular Ad hoc Network. A Driver Support System described in [1] presents an interesting problem: a vehicle should be aware of the state of traffic on a road, up to several kilometers ahead. A system called the TrafficFilter has been proposed in [2] to provide this information. In summary, the TrafficFilter uses multi-hop V2V communication to dissiminate information over distances of several kilometers. This information is expressed in a structure called a TrafficMap. The TrafficMap consists of entries which are sampled representations of the local traffic flow speed, shown in Fig. (a). These samples are produced in a fashion similar to Run-length Encoding.