History of radio § Broadcasting

                                      

                                          Data communications

Wireless Networking:  Automated radio links which transmit digital data between computer and other wireless devices using radio waves, linking the devices together transparently in a computer network. Computer networks can transmit any form of data: in addition to email and web pages, they also carry phone call audio, and video content Security is more of an issue for wireless networks than for wired networks since anyone nearby with a wireless modem can access the signal and attempt to log in. The radio signals of wireless networks are encrypted using WPA.

Wireless LAN: based on the IEEE802.11  standards, these are the most widely used computer networks, used to implement local area network  without cables, linking computers, laptops, cell phones, video game consoles, smart TV and printers in a home or office together, and to a wireless router connecting them to the internet with a wire or cable connection. Wireless routers in public places like libraries, hotels and coffee shops create wireless access points (hotspots) to allow the public to access the Internet with portable devices like smart phones, tablets or laptop. Each device exchanges data using a wireless modem (wireless network interface controller), an automated microwave  transmitter and receiver with an omni directional antenna that works in the background, exchanging data packets with the router. WiFi uses channels in the 2.4 GHz and 5 GHz ISM bands with OFDM (orthogonal frequency division multiplexing) modulation to transmit data at high rates. The transmitters in Wifi modems are limited to a radiated power of 200 mW to 1 watt, depending on country. They have a maximum indoor range of about 150 ft (50 m) on 2.4 GHz and 50 ft (20 m) on 5 GHz.