Research For Routing Protocol Of Vanet In City Scenarios

With the rapid development of automotive industry and wireless communication technology, Inter-Vehicle communication which is based on Ad Hoc network becomes a hot research spot at home and abroad. As an important part of Intelligent Transportation Systems, Vehicular Ad Hoc network (VANET) makes it possible that vehicles share data information with each other, so that it not only expands the drivers’ field of vision, realizes road safety warning, improves the utilization ratio of city traffic, but also provides people with entertainment information service by connecting to the Internet. Routing protocol is one of the major technical difficulties in VANET. Because the nodes in VANET with high mobility, the network topology changes sharply, the links between the nodes disconnect frequently. These factors require that VANET routing protocol should be solved these problems quickly and effectively.Based on describing the work principle and algorithms process of several types of routing protocols for VANET and building NCTUns-6.0 simulation environment with high fidelity characteristic, the paper first builds a realistic urban road traffic scene at the platform and sets relevant parameters, and then makes a simulation on three typical protocol, AODV, DSR, GPSR, and analyzes the root causes of the different network performance between the three protocols.Next the paper states the basic principle and algorithm process of AODV protocol in detail as well as analyzes its deficiency. Also according to the characteristics of vehicular self-organizing network, Improvement is done on AODV. On the premise of ensuring the establishment of routing entry, the improved protocol introduces a mechanism for effective node judgment that limits the broadcasting cope RREQ message. By doing this, the improved one effectively alleviates network congestion, and reduces the number of data loss; besides the thought of adaptive adjustment of hello message broadcasting period based on the change numbers of the neighbor nodes is proposed to improve routing maintenance. At last, AODV and the improved one are simulated on the simulation platform NCTUns-6.0, and the results show that the improved protocol has better network performance in urban road scenes.