Research On Roadside Unit Deployment In Vehicle Ad Hoc Networks

As a special mobile self-organizing network,vehicle ad hoc network cannot ensure the smooth communication among vehicles due to the high moving speed and serious network segmentation problem.Therefore,it is of great significance to carry out vehicular communication with roadside infrastructure.In addition,uniform deployment of a large area of RSUs,while achieving the best network communication capability,also incurs big deployment costs.Therefore,in the case of limited deployment cost,it is of great significance to study the RSU deployment strategy with the purpose of providing efficient coverage value of RSUs combined with vehicle GPS trajectory data.This paper combines the urban road network topology and real vehicle GPS data to optimize the deployment of RSUs,and evaluates the performance of the proposed deployment strategy.The main work is summarized in the following three aspects:(1)Based on the geometric characteristics of urban road network,a complex network model is built.According to the spatial relationship in the road network,intersections are considered to be the network nodes,the segments between the intersections are considered to be the network edges,Traffic flows on the corresponding road segments are considered to be weighs and a road network topology model which composed with intersections and road segments is built.(2)The static deployment method of RSU based on urban grid division is studied.Based on the analysis of urban traffic flow characteristics,a static deployment strategy based on regional connectivity is proposed to improve the connectivity of the entire network.Hotspot detection algorithm is used to locate the location of hotspots in the road network.An integrated RSU deployment strategy is proposed.The strategy considers the area with weak connectivity and the hotspot area with excessive traffic pressure in the road network.Experimental result shows that the proposed deployment strategy can effectively improve the connectivity performance of the vehicle ad hoc network.(3)The dynamic deployment method of RSU based on travel vehicles is studied.The road segment saturation calculation method is used to judge whether the road segment is congested,and the congested paths are found.A dynamic RSU deployment scheme based on the mobile vehicle is proposed,which distributes mobile vehicles carrying RSUs on congested paths.On the remaining congested road segments,static deployment is performed according to the length of the segments.Simulation experiments are carried out to compare the network connectivity performance before and after deployment and indicate that the proposed deployment strategy can improve network connectivity and reduce the deployment cost of RSUs.