Vehicle Precise Positioning Algorithm Of WAVE/DSRC Based On RSSI

In recent years,many countries have begun to find an electronic solution to solve the problem of urban congestion with the problem of traffic congestion in today's world is getting worse.Multi-Line Free Flow electronic toll collection system can effectively alleviate the problem.But the current MLFF electronic toll collection system charges mainly based on the number of the gates that vehicles pass rather than the running distance of the congested road section.The next generation of electronic road toll collection system uses GNSS technology to achieve the goal of charging based on the running distance of the congested road section.The distance-based road pricing scheme is more fair and effective than point-based charging scheme.The MLFF system eliminates the railing of the traditional ETC system,so there exists a cheating phenomenon by using OBU.Including several cheating actions as following:OBU can not be used,including does not install or power off the OBU or does not insert the bank card to avoid billing;replace the type of the OBU to reduce the costs.Therefore,to accurately calculate the location of the vehicle and provide evidence for subsequent enforcement,the OBU audit system is needed.The current wireless location methods based on time of arrival,time difference of arrival,angle of arrival and RSSI values.RSSI based localization techniques do not need to add any external devices since most DSRC modules offer the RSSI parameters nowdays,therefore,this paper uses RSSI-based localization method to achieve the positioning of the OBU.There are two traditional methods of localization technology based on RSSI:localization method based on signal propagation power loss model and localization method based on RSSI fingerprint alignment.Based on the signal propagation power loss model is simple,but it is difficult to implement in practical application.The positioning method based on RSSI fingerprint matching can overcome the shortcomings of reflection and diffraction in signal propagation process,however,the workload of this method is large in offline sampling stage.If the receiving RSSI value varies greatly with the data in the fingerprint database.The error of the positioning result will be very large.In this paper,according to the microwave signal emitted by the same OBU,the signal intensity of the receiver at different positions in the system is regular,so the positioning algorithm of the vehicle in the lateral and vertical positions is proposed.The study found that when the horizontal direction of the 802.11p receiving antenna has a smaller angle,the RSSI sequences received by multiple receiving antennas have significant lateral position statistics,based on this feature,this paper presents a vehicle lateral localization algorithm.It is also found that the RSSI difference between the last receiving antenna and the first receiving antenna has obvious linear correlation with the ordinate,a longitudinal vehicle localization algorithm is proposed based on this feature.Finally,the deviation of the vertical and horizontal coordinates is obtained by using the algorithm proposed in this paper when the vehicle is passing below the antenna and passing between the two antennas.The results obtained by the proposed algorithm are close to the real coordinates,we also compared the difference between the horizontal and vertical coordinates by using three methods,location method based on signal transmission power loss model and Nearest Neighborhood method and K Nearest Neighborhood method.The results show that the algorithm proposed in this paper has the least deviation.