The Designing Of Publishing And Subscribing Protocol In Vehicle Network For Car Service

Nowadays, people in the cities have many travel modes, including public transport, private cars, taxis, etc. The taxis can both meet the needs of people’s personalized travel and reduce related expenses. At the same time, with the growing problems of population surge, traffic jams and taxi uneven distribution, people in the large and medium sized cities have the problem of taxiing difficult especially in the hotspots. However, the average occupancy rate per taxi is very low, which caused great waste of capacity resources.In response to the above problems, we design an information publish and subscription protocol for car servies, combining with VANET, smart moble devices and wireless communication technologies. This protocol can help people quickly find the right vehicle through efficient information exchange process. Meanwhile we introduce carpool mechanisim, which can make full use of vehicle capacity resources and reduce enegy consumption. Detail introductions are as follows:First of all, this paper describes the background knowledge and characteristics of VANET, and summarizes its main application scenarios. Meanwhile we describe the information publish and subscribe model. For the routing strategy of information forwarding in VANET, this paper has a detailed classification research, and specifically addresses the strengths and weaknesses of defferent routing strategies.Secondly, for the protocol we proposed above, this paper introduces the subjects in information exchange and the specific processes of it, and adds carpooling option in the matching process. In addition, the concrete solutions of some key issues are raised, including overtime processing mechanism, privacy security mechanism and incentive mechanism for reducing vehicles’ selfishness. Then, the practical feasibility of the deployment process and the rideshare method are analysed. We can get that existing smart handheld terminals and vehicle terminals can support the protocol. On the other hand, through actual driving data analysis, we can get that using the carpooling way can reduce1/3taxis with same capacity.Furthermore, this paper presents the routing policy of information forwarding. The publish process of information is broadcast routing. There are three routing mechanisms be designed on subscription process, and they are epidemic routing, utility routing and limited copies utility routing. Combined with utility forwarding process, we also designe three formulas of the utility value.Finally, we build a simulation environment to verify the process of information publishing and subscription. By comparing the way to call a car by this protocol with the traditional way of roadside beckoning car, we can obtain using this protocol can significantily improve the success rate of calling a car. Then, those three routing mechanisms are analyzed in four aspects:information delivery success rate, network overhead, average delay information, average number of information hops. The result show the overall performance of limited copies utility routing are better. Moreover, the suggestion routing under diffenrent scenarios are given.