WiFi

Wi-Fi or WiFi is a technology for wireless local area networking with devices based on the IEEE 802.11 standards. A wireless local area network (WLAN) is a wireless computer network that links two or more devices using wireless communication within a limited area such as a home, school, computer laboratory, or office building. Through a gateway, a WLAN can also provide a connection to the wider Internet.
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IEEE 802.11

The IEEE 802.11 standard is a set of media access control (MAC) and physical layer (PHY) specifications for implementing wireless local area network (WLAN) computer communication in the 2.4, 3.6, 5, and 60 GHz frequency bands. They are created and maintained by the IEEE LAN/MAN Standards Committee (IEEE 802). The base version of the standard was released in 1997, and has had subsequent amendments. The standard and amendments provide the basis for wireless network products using the Wi-Fi brand. While each amendment is officially revoked when it is incorporated in the latest version of the standard, the corporate world tends to market to the revisions because they concisely denote capabilities of their products.

Devices that can use Wi-Fi technology include personal computers, video-game consoles, phones and tablets, digital cameras, smart TVs, digital audio players and modern printers. Wi-Fi compatible devices can connect to the Internet via a WLAN and a wireless access point. Such an access point (or hotspot) has a range of about 20 meters (66 feet) indoors and a greater range outdoors. Hotspot coverage can be as small as a single room with walls that block radio waves, or as large as many square kilometres achieved by using multiple overlapping access points.

Wi-Fi most commonly uses the 2.4 gigahertz (12 cm) UHF and 5.8 gigahertz (5 cm) SHF ISM radio bands. Anyone within range with a wireless modem can attempt to access the network, because of this Wifi is more vulnerable to attack (called eavesdropping) than wired networks.

To connect to a Wi-Fi LAN, a computer has to be equipped with a wireless network interface controller. The combination of computer and interface controller is called a station. For all stations that share a single radio frequency communication channel, transmissions on this channel are received by all stations within range. The transmission is not guaranteed to be delivered and is therefore a best-effort delivery mechanism. A carrier wave is used to transmit the data. The data is organised in packets on an Ethernet link, referred to as “Ethernet frames”. Read More

Specifications
Specification Data Rate Modulation Scheme Security
802.11 1 or 2 Mbps in the 2.4 GHz band FHSS, DSSS WEP and WPA
802.11a 54 Mbps in the 5 GHz band OFDM WEP and WPA
802.11b/High Rate/Wi-Fi 11 Mbps (with a fallback to 5.5, 2, and 1 Mbps) in the 2.4 GHz band DSSS with CCK WEP and WPA
802.11g/Wi-Fi 54 Mbps in the 2.4 GHz band OFDM when above 20Mbps, DSSS with CCK when below 20Mbps WEP and WPA
Wikipedia and lantronix.com

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