V2V Path Loss Modeling for Example 5 GHz Overpass Channels

The overpass is a special over-road structure for vehicle transportation, constituting one type of roadway intersection. Real-time communications between on- and under-overpass vehicles can contribute to optimal route selection and overpass accident warning messaging. In this paper, we provide measurement and analytical results for V2V propagation path loss in the 5 GHz band for two example overpasses. These example overpasses are termed the (i) one-lane metal-bottom overpass, and (ii) two-lane metal-bottom overpass. Due to the unique structure of the overpass, we divide the radio wave propagation spaces around the overpass into four different areas: a two-ray area, a short- term partial shadowing area, a (full) shadowing area, and a long-term partial shadowing area. Analysis and measured results for propagation path loss in these areas are provided. In the two-ray area, a line-of-sight (LoS) path and a ground reflected path are present, whereas in the other areas, the overpass body (floor, walls and columns) block the propagation of energy, increasing path loss. We briefly describe our geometry-based models for the overpass V2V channel, which make use of our analytical models and the measurement data.