Radio propagation characteristics in subway platform and tunnel in 2.5 GHz band

Radio propagation in a subway platform and tunnel is investigated at 2.5 GHz band. The propagation loss and fading characteristics are measured by placing a transmitter on the platform and by moving the receivers on the platform as well as in the tunnel. The results of line-of-sight propagation on the platform could be well explained with a propagation model consisting of five dominant waves: a direct wave, and one time-reflected wave from the platform, the ceiling and the two sidewalls. The calculated loss including the fading phenomena agreed well with the experimental result: loss factor with distance is 1.3, which is considerably lower than 2.0, the free space propagation factor. The propagation loss in the tunnel increases suddenly beyond a corner, where no direct-wave is found. In the subway environment, the results for space diversity reception shows the diversity is not so much effective at a long distance in the line-of-sight areas, and it is effective in the out-of-sight areas