Nokia RoofTop™ Wireless Router Installation Guide 21Site survey steps3.1.1 Line of sight analysis3.1.1.1 IntroductionIn order for the Nokia Wireless Router network to operate correctly, theremust be line of sight paths for each link.Determine that there is a visual line of sight and a radio line of sightbetween the router to be installed and its neighboring routers.It is recommended that each router has a line of sight to at least 2 otherrouters to enable several options to route internet traffic to the airhead.Line of Sight and Fresnel Zone - IllustrationVisual line of sightVisual line of sight exists when an imaginary straight line can be drawnbetween two antennas without passing through any physical obstructions.Verifying visual line of sight is the first step in planning the NokiaWireless Router System installation. Observation points must be highenough to allow the viewer to see over ground based obstructions.