Editing Network topology (section)

===Wireless technologies===
[[File:Wireless network.jpg|thumb|right|alt=Black laptop with router in the background |Personal computers are very often connected to networks using wireless links.]]
{{Main|Wireless network}}
*''Terrestrial [[microwave]]''&nbsp;– Terrestrial microwave communication uses Earth-based transmitters and receivers resembling satellite dishes. Terrestrial microwaves are in the low gigahertz range, which limits all communications to line-of-sight. Relay stations are spaced approximately {{convert|50|km|mi|abbr=on|sigfig=1}} apart.
*''[[Communications satellite]]s''&nbsp;– Satellites communicate via microwave radio waves, which are not deflected by the Earth's atmosphere. The satellites are stationed in space, typically in [[geostationary orbit]] {{convert|35786|km|mi|abbr=on}} above the equator. These Earth-orbiting systems are capable of receiving and relaying voice, data, and TV signals.
*''[[Cellular network|Cellular]] and PCS systems'' use several radio communications technologies. The systems divide the region covered into multiple geographic areas. Each area has a low-power transmitter or radio relay antenna device to relay calls from one area to the next area.
*''Radio and [[spread spectrum]] technologies''&nbsp;– Wireless local area networks use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology. Wireless LANs use spread spectrum technology to enable communication between multiple devices in a limited area. [[IEEE 802.11]] defines a common flavor of open-standards wireless radio-wave technology known as [[Wi-Fi]].
*''[[Free-space optical communication]]'' uses visible or invisible light for communications. In most cases, [[line-of-sight propagation]] is used, which limits the physical positioning of communicating devices.