Impact of Vehicle Head Geometric Features in the Propagation Loss of ETC System

The electronic toll collection systems (ETC) are used widely in many countries with its higher toll efficiency. The geometric features of target vehicle and electric conductivity of the application scenarios affect the ray propagating path and path loss of ETC system. In this paper, we propose a propagation loss model for ETC system based on Ray-tracing and Uniform Theory of Diffraction (UTD). According to the car head appearance, we discuss the path losses for cab-over-engine and cab-behind-engine vehicles respectively. Moreover, the additional loss caused by windshield is discussed. Then, we develop a semi-practical simulation environment and an ETC wireless communication comprehensive test instrument. Finally, we analyze the effect of operating frequency, RSU antennas height, length of engine hood, and inclination angle of front windshield. In order to get a better identified performance, the OBU should be placed on the upper half of the front windshield. Experimental and simulation results indicate that the validity of the proposed path loss models.