Propagation Environment Models.

The article focuses on propagation environment models. Except for a vacuum such as outer space, wireless system wave propagation is affected by the elements and characteristics of the real environment in which the networks are deployed. Topographic maps are the fundamental source of information of terrain elevations. The map contains many types of information, including lines of constant elevation, or contours, that undulate across the map. The contour lines are usually drawn at regular elevation spacing so that relative line density is an indicator of how steep or how shallow the terrain slope is.