The Reseacrh On Routing Protocols Of Vehicular Ad Hoc Networks Based On Urban Areas

Nowadays vehicle communication is an increasing research area, The concept of ITS(IntelligentTransportation System) and VANET(Vehicular Ad Hoc Network)was formed under the situations ofthe development of wireless communication network, navigation safety requirements and theinvestments of car manufacturers and Public Transport Authorities. The node’s high mobility,rapidchanges of toplogy in VANET makes its routing protocol design more complex than traditionalmobile ad hoc networks,especially in urban environment,where the node’s mobility is constraintedby the road and wireless signals are blocked by roadside obstacles. So how to design a stable andefficient routing protocol combines with the characteristics of the VANET in urban environment isone of the focus of the study of VANET.Thesis mainly studies position-based routing protocols which are well adapted to VANETcharacteristics. Thesis makes classification and analysis of the advantages and disadvantages ofexisting position-based routing protocols,on the basis of the above work,thesis takes improvementmeasures on the RBVT-R protocol, and gets the improved routing protocol IRBVT-R. ImprovedIRBVT-R has the following advantages:(1)Uses the segmented road node density estimationalgorithm presented in thesis,so that the vehicle can independently obtain more accurate vehicledensity on the long and vehicle uneven distributed road;(2)Makes improvement on the floodingmechanism that used in RBVT-R with road node density,to enable the vehicles to select the bigdensity path in the route establishing process;(3)Under different packet forwarding direction and thevehicle traveling direction, the node’s forwarding priority value is calculated in the packetforwarding process based on effective time of the link between nodes and the distance between thenode’s predicted position and purpose intersection,the node with the largest priority value that hascharacteristics of longer life time and more close to the destination intersection is selected as thenexthop node, to improve the stability of the link and decrease the transmission delay.Finally, thesis uses network simulator NS2with realistic vehicular movement trace filegenerated by node model simulation generator VanetMobiSim to evaluate the performance of theimproved routing scheme and compare that with the original one’s, and results shows that theimproved routing scheme proposed in thesis has a higher packet delivery rate and lowertransmission delay.