Research On Cooperative Positioning Technology In Internet Of Vehicles

5G has brought the world into the era of the Internet of Everything.As an important part of the Internet of Things,the Internet of Vehicles is booming.The Internet of Vehicles takes the moving vehicle as the perceptive object and utilizes the V2 X technology to realize the intelligent driving of vehicles.Positioning technology is a key technology in the Internet of Vehicles,and high precision positioning technology is the premise of realizing intelligent driving.Current vehicle positioning technologies all have some shortcomings,including low accuracy,high complexity of implementation,positioning error accumulation and so on.Cooperative positioning technology can reduce positioning error and achieve high-precision positioning by sharing information between terminals and combining with distance measurement information between terminals.The premise of determining the distance between terminals is to accurately distinguish LOS from NLOS.This paper mainly studies the distinction and use of NLOS,cooperative location technology in vehicle network which includes static cooperative location technology and dynamic cooperative location technology.Firstly,the basic theory of the Internet of Vehicles is introduced,and the concept of V2 X and C-V2 X are explained.This paper points out the key technologies in the Internet of Vehicles,and introduces the positioning technologies in the Internet of Vehicles in detail,and analyzes their advantages and disadvantages.In addition,the discriminating technique of LOS and NLOS based on channel statistical characteristics is also introduced.Secondly,a LOS and NLOS distinguishing method for rapidly changing channels is proposed.This method is based on the signal Angle measurement technology of large-scale MIMO in 5G,and distinguishing LOS from NLOS by analyzing the relationship between signal transmitting Angle and receiving Angle.Considering that there may only be NLOS in practical application,a method to determine the relative position between terminals using NLOS is proposed.This method covers almost all LOS free scenarios,which is simple and effective.Then,in order to put forward the cooperative location technology,the technical foundation of cooperative location technology is analyzed and explained,including statistical inference theory,factor graph and sum product algorithm,and the process of cooperative location technology.On that basis,a static cooperative location technique is proposed.The static positioning scene was digitized,and the joint posterior probability density function was derived to determine the terminal position of the vehicle.The function was represented by a factor graph,and the distance measurement formula was linearized.Based on the factor graph of probability function,the calculating formulas of input information,output information and probability distribution in the factor graph are deduced.Next,on the basis of static cooperative positioning,the dynamic cooperative positioning technology is proposed by adding the displacement of the vehicle terminal.Similar to the static cooperative positioning step,the dynamic positioning scene is digitized,and the joint posterior probability density function is derived to determine the terminal position of the vehicle,and the probability density function combined with vehicle displacement is expressed in the form of a factor graph.The formula of input information,output information and probability distribution is derived based on the factor graph.Finally,MATLAB is used for simulation analysis of cooperative positioning,and the simulation conditions are set according to the actual application scenarios.The simulation independent variables are determined,including distance measurement error variance,the number of vehicle terminals,etc.The final simulation results include static condition and dynamic condition.The simulation results show that the cooperative positioning algorithm can achieve positioning accuracy below meter level,which meets the requirements of highprecision positioning.