Research On Vehicular Cooperate Positioning Technology In Vehicular Ad-hoc Networks

Precise vehicle position and relative position information between vehicles is the foundation ofmany vehicular applications. With the aid of GNSS(Global Navigation Satellite System) andpositioning enhancement techniques, vehicle positioning accuracy can reach10meters around,which could not meet the requirements of the safety applications in VANETs(Vehicular Ad-hocNETworks). When GNSS satellite signals are obscured, the precise position information of orbetween vehicles is harder to obtain. In order to solve the above problems, Vehicular CooperativePositioning method arises.First, a GNSS pseudorange double differencing based method to measure relative positionbetween vehicles is proposed. By double differencing, the public error introduced by satellites orthe propagation path of satellite ranging signals as well as the deviation of receiver clock can beeliminated, and thus accurate relative position information between vehicles is achieved. Simulationresults show that the relative positioning performance of this method improves significantlycompared to the precision of relative positioning information measured by GPS single pointpositioning method.Then, in view of the scene that GNSS satellite signals are obscured, this thesis proposes amethod using the OFDM(Orthogonal Frequency Division Multiplexing) module in V2V wirelesscommunication equipment to measure the distance between vehicles. Through V2V communication,the accurate relative distance information between vehicles can be obtained at the same time. Sincethis method does not depend on the existence of GNSS signals, or other external devices, it has awide application prospect.Finally, on the basis of V2V communication and ranging, combined with the motion equationsof the vehicle, and with the help of free net adjustment theory and kalman filtering method, precisevehicular cooperate positiong can be achieved. Simulation results show that this method has goodpositioning accuracy.