Confidence Level

It is possible to allow links that have obstructions to still be declared valid LOS, particularly if those obstructions are near the boundary of the Fresnel zone.

In addition to the Fresnel radius used by the model ($F_1$), we also compute the first obstruction radius ($F_o$). The confidence level, $C$, refers to the ratio of the latter to the former:

$$C = \frac{F_o}{F_1}$$

Therefore, links without any obstructions have a confidence level of 1. Links with obstructions on the direct LOS signal path have confidence level of 0.

The first obstruction radius depends on the model that is being used. It is the radius of the largest cylinder or ellipsoid that can be constructed without any obstructions. For the cylindrical model, it is simply the shortest distance from the nearest obstruction to the direct LOS signal path.

Users can set a threshold for the confidence level, which is the minimal confidence level required for a valid LOS. Decreasing the level provides more valid LOS links but with greater risk that those links do not have actual LOS during field surveys.