Research On Vehicle Positioning Algorithm Based On IEEE802.11p

In recent years,the massive increase in car ownership has led to a dramatic increase of traffic accidents.Therefore,research on high-precision vehicle positioning is very important for vehicle safety and the development of autonomous driving.Generally,it is hard to get the accurate location with the traditional ultrasonic or laser ranging methods in the non-line of sight(NLOS)condition.Vehicle positioning system based on global navigation satellite systems(GNSS)often fails to operate in the signal dead zone,such as forests,tunnels or downtown.Positioning systems based on vehicular Ad hoc networks(VANETs)can solve e the problem of inaccurate vehicle positioning under NLOS and signal blind zone conditions.In this paper,the 802.11p-based vehicle ranging positioning algorithm is developed on the VANETs system.The specific research is as follows:1.The application of classical time synchronization algorithm in 802.11 p protocol is implemented.Since Orthogonal Frequency Division Multiplexing(OFDM)modulation technology is used in 802.11 p,this paper researches the time synchronization methods based on OFDM system.Based on 802.11 p frame symbols,the OFDM time synchronization algorithms are used for time of arrival(TOA)estimation of vehicle nodes in the VANETs.The studies show that the classical OFDM time synchronization methods can not meet the high-precision ranging requirements of vehicles under the condition of low SNR.2.The TOA estimation of the interval summation based on the result of autocorrelation and cross-correlation(auto-cross)method is proposed in this paper.The results show that it has worse performance in lower SNR,so we propose the mean absolute deviation(MAD)to solve this problem.Simulation results,in the International Telecommunication Union Vehicle A(ITUA)channel,indict that the proposed ranging method achieves superior accuracy than the traditional methods even in low SNR conditions.3.The GUI of simulation and vehicle communication positioning system in Simulink platform are designed.The Simulink based vehicle baseband simulation system includes baseband signal generation,modulation,channel transmission and receiver synchronization modules.The system runs in ITUA channel and NLOS environments,and it can configure parameters more conveniently and display results more intuitively.In this paper,the proposed TOA positioning algorithm is superior to the classical methods in low SNR and multipath environments,which is of great significance for collision warning and automatic driving safety in complex vehicle environments.