Terrestrial microwave – 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 apart. Communications satellites – 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 above the equator. These Earth-orbiting systems are capable of receiving and relaying voice, data, and TV signals. 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 – 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.
terrestrial microwave – 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 apart communications satellites – 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 above the equator these earth-orbiting systems are capable of receiving and relaying voice data and tv signals 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 – 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 80211 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