Research On Service-Intensity Based Vanet Service Disvcovery Strategy And Protocol

With the constant development of automobile industry and the technique of networks, people are more and more eager to communicate wherever and whenever possible. Meanwhile, according to the needs of people, various of services are applied into vehicle networks now, so that only if MANET can be promoted into an intelligent network through effective management, in which the service discovery is the core content, can be met the demands of people for various services. However, there are numerous different network features between VANET and MANET, such as the greater speed of VANET nodes and the location awareness of service request in VANET, which have brought lots of challenges to the service discovery process in VANET. Therefore, it is of great significance to improve the efficiency of service discovery in VANET.The goal of this paper is the research on the location-aware service discovery protocol of VANET. Firstly, we summarized and analyzed the current research status at home and abroad, the unique features of VANET and its influences to the service discovery. And we pointed out the current problems regarding to service discovery in VANET and the way to solve them.Secondly, according to the urban environment of VANET, this paper put forward the concept of Service-Intensity, which is an effective identification of service management and cache. Applying Service-Intensity in the process of service discovery, this paper proposed an efficient forwarding strategy, which can help nodes in VANET transmit service requests through unicast instead of flooding with fewer redundant data packets and higher efficiency of service discovery.Thereafter, Based on the analysis of value added and safety information services, this paper meliorated GPSR routing protocol to the cross-layer service discovery protocol SI_GPSR so that it can provide position assistance function during the process of service discovery, satisfying the demand of location awareness. Furthermore, combining service discovery with route discovery, it can realize the simultaneous discovery of the both, which decreased the control message overhead of service discovery and saved the bandwidth of wireless network. In service discovery, this paper set that priority level of Service-Intensity based forwarding strategy was higher than that of Greedy forwarding, which avoided routing loop effectively.Finally, Based on the mobile model of city environment, this paper took advantage of VanetMobiSim to create network topology of VANET, realizing the application context of both value added and safety information services. According to the network topology model created by VanetMobiSim, this paper designed the simulation experiment of service discovery protocol and compared SI_GPSR with the traditional one via the NS-2 network simulation platform; and the result of the comparison showed the advantages of SI_GPSR.From the results of simulation, we can figure out that SI_GPSR has showed better network performances:making full use of roadside unit in VANET, it reduced the total overall overhead and the delay of service discovery, and enhanced its success rate and accuracy. However, there are still some shortages in the cross-layer service discovery protocol SI_GPSR proposed in this paper, so in the future we will continue our research from the following aspects:(1) service select mechanism, namely that how to select the best service in the process of service discovery; (2) safety authentication mechanism. Due to the openness of wireless radio channel, the design work of protocol in wireless network is faced with serious security threat. So it is of great significance to embed safety authentication mechanism in the process of service discovery.