FIVE-ZONE PROPAGATION MODEL FOR LARGE-SIZE VEHICLES INSIDE TUNNELS

Abstract

An accurate characterization of the wave propagation inside tunnels is of practical importance for the design of advanced communication systems. This paper presents a flve-zone propagation model for large-size vehicles inside tunnels. Compared with existing models, the proposed model considers the in∞uence of the large size of the vehicle, and covers all propagation mechanism zones and their dividing points. When a large-size vehicle is passing the transmitter, the received power sufiers a deep fading as the direct wave is blocked by the vehicle itself. This zone is called the near shadowing zone. Then, when the vehicle has moved past the transmitter, the line of sight is recovered. If the vehicle is still close to the transmitter, the free space propagation zone starts. Then, as the distance increases, the vehicle enters the multi-mode propagation zone, where higher order modes are signiflcant. Further away, when high order modes are greatly attenuated, guided propagation is stabilized. Finally, when the vehicle is extremely far from the transmitter, the waveguide efiect vanishes because of the attenuation of re∞ected rays. Two sets of measurements are employed to validate the model. Results show good agreement, and therefore, the model presents an efiective way to predict the propagation inside tunnels for large-size vehicles.