The Study And Analysis Of Communications Of Vehicular AD HOC Networks Based On IEEE802.11P/1609.X Protocol

In recent years, with the growing numbers of the vehicles on road, the accidents caused by vehicles increased greatly, which leads to the development of the new generation of Intelligent Transport System that can help the drivers drive safely. The main cause of the accidents is the driver’s failure to react to the changing circumstance of the road. In fact, if the drivers can get the information of the traffic using wireless communication technology, most of the accidents can be avoid. IEEE adopted the WAVE protocol as the main technology used in VANETs, which include the802.11p protocol and the1609.X protocol. These protocols can deal with the unstable topology of the vehicular networks, and they can provide reliable communication among cars.In this thesis, we first introduce the current research status of the Intelligent Transport System, and then we give the basic introduction of the WAVE protocol. We analyze the wireless channel of the VANETs, discuss the optimal transmition models for VANETs, and we discuss the hidden terminal problem. Then, we analyze a model which considers the car following rules, and we get the relation of network density and car speed.In the meantime, a lot of the researchers believe that broadcast and multihop communications are dominant in VANETs’safety applications and protocols. So in this thesis, we analyze a network topology based multihop scheme, which can alleviate the broadcast storm problem. The scheme is based on the knowledge of the neiboughhood of the vehicles and related traffic parameters to reduce the channel competition, redundant rebroadcast, and the message deliver time, which can increase the success rate of message receiving. Also we analyze an architecture that involves the buses, which can change the original way of message dissemination, using the buses as the carrier for message, it can increase the success rate of safety related message. In this thesis, we use the network communication simulator NS-3and the micro traffic simulator SUMO for simulation, which can be realistic and thus have accurate simulation results.