Study of propagation model and fading characteristics for wireless relay system between long-haul train cars

This paper presents a propagation model and fading characteristics for a wireless relay system between long-haul train cars under both static and moving conditions. The proposed model is based on the observation results of a measurement campaign using an actual long-haul high-speed train. The measurement results indicate that the propagation loss between relay stations is greatly affected by waves that re-enter the train. The proposed propagation model, which comprises two wave components, is established based on the results. One wave component comprises the waves traveling inside the train cars, and the other represents waves that re-enter the car from outside of the train cars (re-entering waves). The fading characteristics between the relay stations in the train cars are also revealed based on the proposed propagation model. The fading variations of both the wave component traveling inside train cars and the re-entering wave component indicate Nakagami-Rician fading. Hence, the total fading characteristics between the relay stations in the train cars can be accounted for by considering the results of the combination of those two Nakagami-Rician fading components. The proposed model and fading characteristics are useful in designing radio zones of a relay system between train cars.