Contention-based Forwarding Routing Protocol For Vehicular Networks In Urban Scenarios

Vehicular networks is an emerging field which has great development potential. It can enhance traffic safety, improve the urban transportation efficiency, as well as provide a variety of location-related information services. Because the mobile nodes in vehicular networks are subject to road limit, and the fast-moving nodes of vehicular networks lead to fast changes of network topology, the routing technology, as one of the key technologies, to a large extent determines the network performance of the whole vehicular networks. As the reliable broadcast of location-based routing protocol has strong adaptability to the dynamic changes of network topology, it can better solve the network segmentation problem in vehicular networks. So this paper first investigates the broadcast routing protocol in vehicular networks, and then presents an improved CBF routing protocol.This paper firstly introduces the structure, the main features and application of vehicular networks, then summarizes and concludes the classic routing protocols mentioned in recent literatures. Secondly, it also analyzes the limitations of the existing CBF protocol, based on this, presents an improved CBF protocol called ICBFP for the urban scenarios. ICBFP protocol improves the path selection strategy of CBF, considering the physical length of the path and real-time traffic information, and in the competition strategy comprehensively considerate the movement direction and mobile speed of the vehicle nodes, forks in the road and other factors. In addition, in order to further reduce the end-to-end delays and routing overhead during packet forwarding, and improve the packet delivery rate, in ICBFP, a node broadcasts packets to the neighbor nodes, and the time interval between the previous sending is less thanε, it no longer takes once and twice competitive strategy, but directly unicast the packet to the previous node which successfully competes, to change broadcast strategy into unicast strategy. As the node mobility model of vehicular networks does not simply use the traditional random node model, in order to make the simulation results and the actual scene more identical, in the simulation this paper tries to use the node mobility model which can reflect as far as possible the vehicle’s actual movement. Then, based on the analysis of the model and the characteristics of the vehicle movement, this paper introduces the uses of traffic simulation software VanetMobiSim, also establish VanetMobiSim and OPNET co-simulation platform to describe the real vehicle node mobile track. Finally, this paper uses OPNET network simulation tool to evaluate the performance of routing protocol of vehicular networks, and develops OPNET modeling for the improved CBF protocol, based on the GRP model of OPNET. The simulation results show that ICBFP protocol has a better performance than GPSR protocol and CBF protocol in urban scene.