A two-step positioning algorithm for an ITS based on RFID

The problem of vehicle positioning is investigated in this paper. A cellular vehicle positioning system is proposed for vehicle positioning, and a novel vehicle positioning method which based on TDOA (Time Difference of Arrival) is proposed. The cellular vehicle positioning system is composed of base stations, electronic plates and a control center. The vehicle positioning method is a two-step method, derived from the classic Chan method. An approximate position of a vehicle can be estimated in the first step. Then the three base stations that have the highest SNR of the received signal can be found, and the two TDOA values of these three base stations are employed to calculate the vehicle´s position. Simulation results show that the proposed positioning method gives a better positioning performance than classic Chan algorithm.