Terrain-Scatter Augmented Vertical Plane Model for Radio Path Loss Estimation in Complex Terrain: (Invited Paper)

The fundamental challenge of complex (typically mountainous or urban) terrain for radio-frequency systems is that a direct line-of-sight is difficult or impossible to achieve between a radio transmitter and receiver. In the context of ground-based military operations, occupying line-of-sight positions to optimize communications or surveillance capabilities often exposes Soldiers and/or equipment to unacceptable risks from both conventional and electronic warfare. Propagation models for tactical use commonly analyze terrain only in the vertical plane containing both transmitter and receiver in order to simplify both the required data and computational burdens. However, these advantages come at the cost of ignoring reflections from topography within and outside the vertical plane path, which can have serious implications for radio-frequency direction finding, surveillance, and high-speed data transfer in complex terrain. This work summarizes our efforts to address these issues by developing a hybrid path loss model, one specifically designed for ground-to-ground radio links in complex rural terrain. The model uses an existing international-standard vertical plane diffraction model (VPM) to account for path losses associated with obstacles, and then augments those results with geospatially derived terrain reflection/scattering effects. Our prototype Terrain Scatter Augmented Vertical Plane Model (TSAVPM) provides physically credible path loss results in complex terrain at tactically relevant spatial scales (∼250 sq. km) and computational costs (under 40 seconds on a single 4.2 GHz central processing unit).