Wi-Fi
Wi-Fi (/ˈwaɪfaɪ/)[1][a] is a family of wireless network protocols based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio waves. These are the most widely used computer networks, used globally in home and small office networks to link devices and to provide Internet access with wireless routers and wireless access points in public places such as coffee shops, hotels, libraries, and airports to provide visitors.
Introduced
21 September 1997
Wi-Fi is a trademark of the Wi-Fi Alliance, which restricts the use of the term "Wi-Fi Certified" to products that successfully complete interoperability certification testing.[3][4][5] Non-compliant hardware is simply referred to as WLAN, and it may or may not work with "Wi-Fi Certified" devices. As of 2017, the Wi-Fi Alliance consisted of more than 800 companies from around the world.[6] As of 2019, over 3.05 billion Wi-Fi-enabled devices are shipped globally each year.[7]
Wi-Fi uses multiple parts of the IEEE 802 protocol family and is designed to work seamlessly with its wired sibling, Ethernet. Compatible devices can network through wireless access points with each other as well as with wired devices and the Internet. Different versions of Wi-Fi are specified by various IEEE 802.11 protocol standards, with different radio technologies determining radio bands, maximum ranges, and speeds that may be achieved. Wi-Fi most commonly uses the 2.4 gigahertz (120 mm) UHF and 5 gigahertz (60 mm) SHF radio bands, with the 6 gigahertz SHF band used in newer generations of the standard; these bands are subdivided into multiple channels. Channels can be shared between networks, but, within range, only one transmitter can transmit on a channel at a time.
Wi-Fi's radio bands work best for line-of-sight use. Many common obstructions, such as walls, pillars, home appliances, etc., may greatly reduce range, but this also helps minimize interference between different networks in crowded environments. The range of an access point is about 20 m (66 ft) indoors, while some access points claim up to a 150 m (490 ft) range outdoors. Hotspot coverage can be as small as a single room with walls that block radio waves or as large as many square kilometers using many overlapping access points with roaming permitted between them. Over time, the speed and spectral efficiency of Wi-Fi have increased. As of 2019, some versions of Wi-Fi, running on suitable hardware at close range, can achieve speeds of 9.6 Gbit/s (gigabit per second).[8]
Etymology and terminology[edit]
The name Wi-Fi, commercially used at least as early as August 1999,[30] was coined by the brand-consulting firm Interbrand. The Wi-Fi Alliance had hired Interbrand to create a name that was "a little catchier than 'IEEE 802.11b Direct Sequence'."[31][32] According to Phil Belanger, a founding member of the Wi-Fi Alliance, the term Wi-Fi was chosen from a list of ten names that Interbrand proposed.[31] Interbrand also created the Wi-Fi logo. The yin-yang Wi-Fi logo indicates the certification of a product for interoperability.[33] The name is often written as WiFi, Wifi, or wifi, but these are not approved by the Wi-Fi Alliance.
The name Wi-Fi is not short-form for 'Wireless Fidelity',[34] although the Wi-Fi Alliance did use the advertising slogan "The Standard for Wireless Fidelity" for a short time after the brand name was created,[31][33][35] and the Wi-Fi Alliance was also called the "Wireless Fidelity Alliance Inc." in some publications.[36] IEEE is a separate, but related, organization and their website has stated "WiFi is a short name for Wireless Fidelity".[37][38] The name Wi-Fi was partly chosen because it sounds similar to Hi-Fi, which consumers take to mean high fidelity or high quality. Interbrand hoped consumers would find the name catchy, and that they would assume this wireless protocol has high fidelity because of its name.[39]
Other technologies intended for fixed points, including Motorola Canopy, are usually called fixed wireless. Alternative wireless technologies include Zigbee, Z-Wave, Bluetooth and mobile phone standards.
To connect to a Wi-Fi LAN, a computer must be equipped with a wireless network interface controller. The combination of a computer and an interface controller is called a station. Stations are identified by one or more MAC addresses.
Wi-Fi nodes often operate in infrastructure mode in which all communications go through a base station. Ad hoc mode refers to devices communicating directly with each other, without communicating with an access point.
A service set is the set of all the devices associated with a particular Wi-Fi network. Devices in a service set need not be on the same wavebands or channels. A service set can be local, independent, extended, mesh, or a combination. Each service set has an associated identifier, a 32-byte service set identifier (SSID), which identifies the network. The SSID is configured within the devices that are part of the network. A basic service set (BSS) is a group of stations that share the same wireless channel, SSID, and other settings that have wirelessly connected, usually to the same access point.[40]: 3.6 Each BSS is identified by a MAC address called the BSSID.
Several other wireless technologies provide alternatives to Wi-Fi for different use cases:
Some alternatives are "no new wires", re-using existing cable:
Several wired technologies for computer networking, which provide viable alternatives to Wi-Fi: