Spatiotemporal Random Modeling Of Vehicular Traffic In Vanets And Application

As one of the research hotspots in the field of intelligent transportation,the research focus on VANETs(Vehicular Ad Hoc Wireless Networks)has gradually shifted from information platform building dominated by electronic engineering and computer technology to the integration of traffic engineering,control engineering,communication engineering and other disciplines.The VANETs intermittent connectivity is one of the key issues.Due to the limited range of DSRC,the connectivity"empty" in the vehicle network will lead to the interruption and delay of the information transmission,when the vehicle spacing is relatively large or the penetration of networked vehicles is lower.At the beginning of VANETs,it is almost impossible to achieve connectivity in the whole network due to the low penetration of networked vehicles.Therefore,it is necessary to research and evaluate the basic connectivity of VANETs.The average delay of information transmission is a basic index to measure the connectivity of VANETs.To enhance connectivity,RSU(Roadside Stationary Units)can be used as an auxiliary means of information transmission between vehicles,in order to reduce the delay in transmission and improve the stability and reliability of information connectivity in VANETs.VANETs connectivity is mainly affected by the state of traffic flow and the penetration of networked vehicles.Since the average space headway plays an important role in connectivity,accurate vehicle space distribution is the key to study vehicle connectivity.Based on the time-dependent Poisson characteristics of vehicle arrival in traffic engineering,this paper discusses the spatial distribution of vehicles and the related mathematical models,then studies the spatial/temporal distribution of vehicles,the distribution of vehicle type,the overtaking distribution and other issues.The work of the paper reveals the intrinsic relationship,and transition mechanism between the temporal Poisson process and the spatial Poisson process under the free flow condition.The studies further solidifies the theoretical foundation for the connectivity research.In addition,this paper also studies the delivery delays in VENATs based on RSUs under free-flow conditions,and establishes the mathematical connection between delivery delay,traffic flow parameters,RSUs spacing and traffic accident parameters.This will be an important reference for the future practice of VANETs,especially how to install less roadside unit deployment to enhance the network connectivity.