Deploying License-Free Wireless Wide-Area Networks

Obtaining Wireless Line-of-Sight Paths

When a wireless signal encounters an obstruction, the signal is always attenuated and often reflected or diffracted. With outdoor wireless WANs, the attenuation from these encounters is usually so great that not enough signal remains to be detected at the other end of the link. When you design a wireless WAN link, it is important to work to achieve a wireless line-of-sight (LOS) path. This is a path that has no obstructions to significantly block, diffract, absorb, or attenuate the wireless signal. A wireless LOS path typically requires a visual LOS path plus additional path clearance to account for the spreading of the wireless signal. The following paragraphs describe visual and wireless LOS paths and ...