Routing Strategy Research On Warning In Vehicular Ad-hoc Network On Highway

With rapid development of the economic society and "the age of the automobile", the traffic problem has been increasing, and traffic accidents have become a global public safety issues. As a new subject, intelligent transportation system is causing attention from academic circles and big famous auto manufacturers. And vehicular ad hoc network is one of the important means of the realization of intelligent transportation, and is increasingly valued by the whole society. So far, there is no routing protocol which is really suitable for vehicular ad hoc network. The paper conducts researches on the routing strategy of vehicular ad hoc network warning on highway.Firstly, the paper introduces research background, concepts, characteristics, key technology, application, development process and current situation of mobile ad hoc network. Based on it, vehicular ad hoc network, which is regarded as a special mobile ad hoc network, is described. And a simple and practical model is presented, which provides a solid foundation for doing simulation experiment smoothly, truly and reliably.Secondly, the paper introduces the network simulator, NS-2 and simply describes the basic simulation process. Network simulator is very important, as it is the basic tool for network simulation.Thirdly, the paper introduces routing protocols of the mobile ad hoc network, and the two typical routing protocol AODV and simulated DSDV compare for improved after routing protocol to lay the foundation.Finally, the AODV routing protocol is improved and a new AODV_BD routing protocol is put forward. End-to-end delay and packet delivery rate is compared from three aspects -- moving velocity,packet frequency and scene size about DSDV routing protocol and AODV routing protocol and we can see that the delay on DSDV routing protocol is small than one on AODV routing protocol, but packet delivery rate also small. But because DSDV routing protocol is a kind of active routing protocol, and when network size is increasingly big, its performance will be very poor, so we improve AODV routing protocol. When the traditional AODV routing protocol searches routing or routing fails, it always broadcasts route requests packet first, and then builds routing, then sends packets, so the packet delay is increased. While AODV_BD routing protocol broadcasts an improved data packet when searching for routing, instead of broadcasting routing request packet. The improved data packet can not only establish routing but also spread data, which reduces delay in a certain extent. The simulation results show that AODV_BD routing protocol reduces the delay and improve the real-time data distribution.