| VANET is important as intelligent transportation field of mobile communication platform, to play an important role in enhancing transport efficiency, reduce traffic pressure, driver assistance and accident warning and car entertainment.VANET is a special application in inter-vehicle communication in mobile ad hoc networks. VENET derived from traditional MANET, but there are a lot of its own characteristics, such as node speed faster, network topology change more frequently, network vulnerable to traffic conditions, space constraints, etc., seriously affect the normal data packet transmission efficiency,and lead to the original Internet protocol cannot play a proper role directly in the VANET, therefore, how to realize the fast dynamic and efficient routing protocol adapted to VANET become the research focus.This thesis first describes the Ad Hoc technology, the architecture, features and application of VANET. And some representative proposed routing protocol working mechanism and performance were classified and compared.In order to simulate the performance of routing protocols in urban traffic scenes, it firstly analyzes the existing node motion model, due to considering the urban traffic scenarios vehicle movement inevitably affected by traffic speed, road structure, intersection, traffic lights, multi-lane lane change and other factors. In this paper by reference optimized intelligent driving model IDM, and combined with Goole Earth topology extraction urban roads topology of satellite maps,to reflect the reality of the urban traffic scene and the characteristics of mobile vehicles node, on the basis of experiment contrast evaluated the traffic flow movement speed and different mobile node model for the influence of the network protocol performance. Analysis into the optimization of the intelligent driving model features, to reflect the movement of vehicles node urban traffic environment more authenticity. Analysts believe that the introduction of intelligent driving model characteristics optimized to reflect the movement of vehicles nodes in urban traffic environment more authenticity.For geographic routing protocols GPSR in the network topology changes frequently VANET adaptive stronger, this thesis discusses the defects of GPSR protocol algorithm and improve the working mechanism and strategy, since GPSR protocol is based on the location of the node data forwarding, the node high-speed mobile lead to the location information constantly changing,and affect the normal data forwarding problem. This thesis first to the next hop neighbor node selection of greedy algorithm is introduced into judgment mechanism, mainly by reference node movement speed, direction and distance parameters, so as to improve the reliability of communication link.In the GPSR protocol since the destination node location n information obtained by location service,and in data forwarding initially has been set by the source node, and remains unchanged in the whole process of data transmission, However, in practice the position changes of the destination node may cause the data packet is not sent to the destination node successfully. this paper adds to the destination node expectations Domain, which is based on the original location of the destination node as the center,and R is the radius of the circle, to estimate the range of its movement according to the destination node expectations domain, when a node detects its neighbor list contains the destination node ID,it is not immediately forwarding the data to the destination node, but to be a judgment, it is to meet the wireless coverage of this node to cover the movement expectations domain of the destination node. Only can be selected as a forwarding node to the destination node, thus ensuring the destination node can be fully received data information of the source node. To improve the accuracy of the data communication. The simulation experimental results show that the improved GPSR protocol has a higher packet delivery rate than the original GPSR... |
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