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Wi-Fi () is a family of
wireless network A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking is a method by which homes, telecommunications networks and business installations avoid the costly process of introducing c ...

wireless network
protocols Protocol may refer to: Sociology and politics * Protocol (politics)Protocol originally (in Late Middle English, c. 15th century) meant the minute or logbook taken at a meeting, upon which an agreement was based. The term now commonly refers to an a ...
, based on the
IEEE 802.11 IEEE 802.11 is part of the IEEE 802 IEEE 802 is a family of Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers (IEEE) is a professional association for electronic engineering and electri ...
family of standards, which are commonly used for
local area network A local area network (LAN) is a that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a (WAN) not only covers a larger geographic distance, but also ge ...
ing of devices and
Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a ''internetworking, network of networks'' that consist ...

Internet
access, allowing nearby digital devices to exchange data by
radio wave Radio waves are a type of electromagnetic radiation In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies ma ...
s. These are the most widely used computer networks in the world, used globally in home and small office networks to link desktop and
laptop A laptop, laptop computer, or notebook computer is a small, portable personal computer File:Crystal Project computer.png, upright=0.9, An artist's depiction of a 2000s-era desktop-style personal computer, which includes a metal case with ...

laptop
computers,
tablet computer A tablet computer, commonly shortened to tablet, is a mobile device A mobile device (or handheld computer) is a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations auto ...
s,
smartphone A smartphone is a Mobile device, portable device that combines Mobile phone, mobile telephone and Mobile computing, computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and exten ...

smartphone
s,
smart TV A smart TV, also known as a connected TV (CTV), is a traditional television set A Sony Wega CRT television set A television set or television receiver, more commonly called a television, TV, TV set, telly, or tele, is a device that combines a ...
s,
printers Printers may be: Technology * Printer (publishing) In publishing, printers are both companies A company, abbreviated as co., is a legal entity In law, a legal person is any person A person (plural people or persons) is a being th ...
, and
smart speaker A smart speaker is a type of loudspeaker and voice command device with an integrated virtual assistant (artificial intelligence), virtual assistant that offers interactive actions and Hands-free computing, hands-free activation with the help of on ...
s together and to a
wireless router A wireless router is a device that performs the functions of a Router (computing), router and also includes the functions of a wireless access point. It is used to provide access to the Internet or a Private network, private computer network. Dep ...

wireless router
to connect them to the Internet, and in
wireless access point #REDIRECT Wireless access point#REDIRECT Wireless access point In computer networking, a wireless access point (WAP), or more generally just access point (AP), is a networking hardware device that allows other Wi-Fi Wi-Fi () is a family ...

wireless access point
s in public places like coffee shops, hotels, libraries and airports to provide the public Internet access for mobile devices. ''WiFi'' is a trademark of the non-profit
Wi-Fi Alliance The Wi-Fi Alliance is a non-profit organization that owns the Wi-Fi Wi-Fi () is a family of wireless network A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking is a met ...
, which restricts the use of the term ''Wi-Fi Certified'' to products that successfully complete
interoperability Interoperability is a characteristic of a product or system, whose interfaces are completely understood, to work with other products or systems, at present or in the future, in either implementation or access, without any restrictions. While the ...
certification testing. , the Wi-Fi Alliance consisted of more than 800 companies from around the world. , over 3.05 billion Wi-Fi enabled devices are shipped globally each year. Wi-Fi uses multiple parts of the
IEEE 802 IEEE 802 is a family of Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers (IEEE) is a professional association for electronic engineering and electrical engineering (and associated disciplin ...

IEEE 802
protocol family and is designed to interwork seamlessly with its wired sibling
Ethernet Ethernet () is a family of wired computer network A computer network is a set of s sharing resources located on or provided by . The computers use common s over to communicate with each other. These interconnections are made up of te ...

Ethernet
. Compatible devices can network through
wireless access point #REDIRECT Wireless access point#REDIRECT Wireless access point In computer networking, a wireless access point (WAP), or more generally just access point (AP), is a networking hardware device that allows other Wi-Fi Wi-Fi () is a family ...

wireless access point
s to each other as well as to wired devices and the Internet. The different versions of Wi-Fi are specified by various IEEE 802.11 protocol standards, with the different radio technologies determining radio bands, and the maximum ranges, and speeds that may be achieved. Wi-Fi most commonly uses the
UHF Ultra high frequency (UHF) is the ITU 260px, ITU Monument, Bern The International Telecommunication Union is a specialized agency of the United Nations responsible for all matters related to information and communication technologies ...

UHF
and SHF radio bands; these bands are subdivided into multiple channels. Channels can be shared between networks but only one transmitter can locally transmit on a channel at any moment in time. Wi-Fi's wavebands have relatively high absorption and 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. An access point (or hotspot) often has a range of about indoors while some modern access points claim up to a 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 (miles) using many overlapping access points with
roaming Roaming is a wireless Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points that do not use an electrical conductor as a medium by which to perform the transfer. The most ...

roaming
permitted between them. Over time the speed and spectral efficiency of Wi-Fi have increased. As of 2019, at close range, some versions of Wi-Fi, running on suitable hardware, can achieve speeds of 9.6 Gbit/s (
gigabit The gigabit is a multiple of the unit bit The bit is a basic unit of information in computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of al ...
per second).


History

A 1985 ruling by the U.S. Federal Communications Commission released parts of the
ISM band The ISM radio bands are portions of the radio spectrum The radio spectrum is the part of the electromagnetic spectrum The electromagnetic spectrum is the range of frequencies (the spectrum A spectrum (plural ''spectra'' or ''spectrums'') ...
s for unlicensed use for communications. These frequency bands include the same 2.4 GHz bands used by equipment such as microwave ovens and are thus subject to interference. A Prototype Test Bed for a wireless local area network was developed in 1992 by researchers from the Radiophysics Division of
CSIRO The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government The Australian Government, also known as the Commonwealth Government, is the national government of Australia Australia, offici ...

CSIRO
in Australia. About the same time in The Netherlands in 1991, the
NCR Corporation NCR Corporation, previously known as National Cash Register, is an American software, managed and professional services, consulting and technology company. It manufactures self-service kiosks, point-of-sale terminals, automated teller machine ...
with
AT&T Corporation AT&T Corporation, originally the American Telephone and Telegraph Company, is the subsidiary of AT&T Inc. that provides voice, video, data, and Internet The Internet (Capitalization of Internet, or internet) is the global system of i ...
invented the precursor to 802.11, intended for use in cashier systems, under the name WaveLAN. NCR's Vic Hayes, who held the chair of IEEE 802.11 for 10 years, along with
Bell Labs Nokia Bell Labs (formerly named Bell Labs Innovations (1996–2007), AT&T Bell Laboratories (1984–1996) and Bell Telephone Laboratories (1925–1984)) is an American industrial research and scientific development company A company, abbrev ...
Engineer Bruce Tuch, approached IEEE to create a standard and were involved in designing the initial 802.11b and 802.11a standards within the
IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operations center i ...
. They have both been subsequently inducted into the Wi-Fi NOW Hall of Fame. The first version of the 802.11 protocol was released in 1997, and provided up to 2 Mbit/s link speeds. This was updated in 1999 with
802.11b IEEE 802.11b-1999 or 802.11b is an amendment to the IEEE 802.11 IEEE 802.11 is part of the IEEE 802 IEEE 802 is a family of Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers (IEEE) is a ...
to permit 11 Mbit/s link speeds, and this proved popular. In 1999, the
Wi-Fi Alliance The Wi-Fi Alliance is a non-profit organization that owns the Wi-Fi Wi-Fi () is a family of wireless network A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking is a met ...
formed as a trade association to hold the Wi-Fi trademark under which most products are sold. The major commercial breakthrough came with
Apple Inc. Apple Inc. is an American multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countries * Multinational force, a military body from multiple countries * Multinational state, a ...
adopting Wi-Fi for their
iBook iBook is a line of laptop computer A laptop or laptop computer is a small, portable personal computer File:Crystal Project computer.png, upright=0.9, An artist's depiction of a 2000s-era desktop-style personal computer, which include ...

iBook
series of laptops in 1999. It was the first mass consumer product to offer Wi-Fi network connectivity, which was then branded by Apple as
AirPort An airport is an with extended facilities, mostly for commercial air transport. Airports often have facilities to park and maintain aircraft, and a . An airport consists of a , which comprises an aerially accessible open space including a ...

AirPort
. This was in collaboration with the same group that helped create the standard Vic Hayes, Bruce Tuch, Cees Links, Rich McGinn, and others from
Lucent Lucent Technologies, Inc., was an American Multinational corporation, multinational telecommunications equipment company headquartered in Murray Hill, New Jersey, Murray Hill, New Jersey, in the United States. It was established on September 30, 19 ...

Lucent
. Wi-Fi uses a large number of patents held by many different organizations. In April 2009, 14 technology companies agreed to pay Australia's
CSIRO The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government The Australian Government, also known as the Commonwealth Government, is the national government of Australia Australia, offici ...

CSIRO
$1 billion for infringements on CSIRO patents. Australia claims Wi-Fi is an Australian invention, at the time the subject of a little controversy. CSIRO won a further $220 million settlement for Wi-Fi patent-infringements in 2012, with global firms in the United States required to pay CSIRO licensing rights estimated at an additional $1 billion in royalties. In 2016, the CSIRO wireless local area network (WLAN) Prototype Test Bed was chosen as Australia's contribution to the exhibition ''
A History of the World in 100 Objects ''A History of the World in 100 Objects'' was a joint project of BBC Radio 4 BBC Radio 4 is a British national radio station owned and operated by the BBC. It broadcasts a wide variety of Talk radio, spoken-word programmes including news, dr ...
'' held in the
National Museum of Australia The National Museum of Australia, in the national capital Canberra Canberra ( ) is the capital city of Australia. Founded following the Federation of Australia, federation of the colonies of Australia as the seat of government for the ne ...

National Museum of Australia
.


Etymology and terminology

The name ''Wi-Fi'', commercially used at least as early as August 1999, 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'." Phil Belanger, a founding member of the Wi-Fi Alliance, has stated that the term ''Wi-Fi'' was chosen from a list of ten potential names invented by Interbrand. The name ''Wi-Fi'' has no further meaning, and was never officially a shortened form of "Wireless Fidelity". Nevertheless, the Wi-Fi Alliance used the
advertising slogan Advertising slogans are short phrases used in advertising campaign Advertising is a marketing communication that employs an openly sponsored, non-personal message to promote or sell a product, service or idea.William J. Stanton. ''Fundamenta ...
"The Standard for Wireless Fidelity" for a short time after the brand name was created, and the Wi-Fi Alliance was also called the "Wireless Fidelity Alliance Inc" in some publications. The name is often written as ''WiFi'', ''Wifi'', or ''wifi'', but these are not approved by the Wi-Fi Alliance.
IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operations center i ...
is a separate, but related, organization and their website has stated "WiFi is a short name for Wireless Fidelity". Interbrand also created the Wi-Fi
logo A logo (abbreviation of logotype; ) is a graphic Graphics (from Greek ''graphikos'', "belonging to drawing") are visual images or designs on some surface, such as a wall, canvas, screen, paper, or stone to inform, illustrate, or entertain ...

logo
. The
yin-yang In Ancient Chinese philosophy, yin and yang ( and ; zh, t= ''yīnyáng'' pronounced , lit. "bright-black", "positive-negative") is a concept of dualism, describing how seemingly opposite or contrary forces may actually be complementary, ...

yin-yang
Wi-Fi logo indicates the certification of a product for
interoperability Interoperability is a characteristic of a product or system, whose interfaces are completely understood, to work with other products or systems, at present or in the future, in either implementation or access, without any restrictions. While the ...

interoperability
. Non-Wi-Fi technologies intended for fixed points, such as
Motorola Canopy Cambium Networks (formerly known as Motorola Canopy) is a wireless infrastructure provider that offers fixed wireless and Wi-Fi to broadband service providers and enterprises to provide Internet access Internet access is the ability of indiv ...
, are usually described as
fixed wireless Fixed wireless is the operation of wireless Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points that do not use an electrical conductor as a medium by which to perform t ...
. Alternative wireless technologies include mobile phone standards, such as , , 4G, 5G and LTE. To connect to a Wi-Fi LAN, a computer must be equipped with a
wireless network interface controller A wireless network interface controller (WNIC) is a network interface controller A network interface controller (NIC, also known as a network interface card, network adapter, LAN adapter or physical network interface, and by similar terms) ...
. The combination of a computer and an interface controller is called a ''
station Station may refer to: Agriculture * Station (Australian agriculture) In Australia, a station is a large landholding used for producing livestock Livestock is commonly defined as domesticated Domestication is a sustained multi-generatio ...
''. Stations are identified by one or more
MAC address A media access control address (MAC address) is a unique identifier A unique identifier (UID) is an identifier An identifier is a name that identifies (that is, labels the identity of) either a unique object or a unique ''class'' of objects, ...
es. Wi-Fi nodes often operate in ''infrastructure mode'' where all communications go through a base station. '' Ad hoc mode'' refers to devices talking directly to each other without the need to first talk to 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, or mesh or a combination. Each service set has an associated identifier, the 32-byte ''Service Set Identifier (SSID)'', which identifies the particular network. The SSID is configured within the devices that are considered part of the network. A ''Basic Service Set'' (''BSS'') is a group of stations that all share the same wireless channel, SSID, and other wireless settings that have wirelessly connected (usually to the same access point). Each BSS is identified by a MAC address which is called the ''BSSID''.


Certification

The
IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operations center i ...
does not test equipment for compliance with their standards. The
non-profit A nonprofit organization (NPO), also known as a non-business entity, not-for-profit organization, or nonprofit institution, is a legal entity organized and operated for a collective, public or social benefit, in contrast with an entity that o ...
Wi-Fi Alliance was formed in 1999 to fill this void—to establish and enforce standards for interoperability and
backward compatibility Backward compatibility (sometimes known as backwards compatibility) is a property of a system, product, or technology that allows for interoperability Interoperability is a characteristic of a product or system, whose interfaces are completely ...
, and to promote
wireless Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points that do not use an electrical conductor In physics Physics (from grc, φυσική (ἐπιστήμη), ph ...

wireless
local-area-network technology. , the Wi-Fi Alliance includes more than 800 companies. It includes
3Com 3Com Corporation was a digital electronics manufacturer best known for its computer network A computer network is a set of s sharing resources located on or provided by . The computers use common s over to communicate with each other. Th ...
(now owned by HPE/Hewlett-Packard Enterprise), Aironet (now owned by
Cisco Cisco Systems, Inc. (Cisco) is an American multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countries * Multinational force, a military body from multiple countries * Multina ...

Cisco
),
Harris Semiconductor Harris Corporation was an American technology company, defense contractor The arms industry, also known as the arms trade, is a global industry classification, industry which manufacturing, manufactures and sells weapons and military technology ...
(now owned by
Intersil Intersil is an American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the United States The United States of America (USA), commonly known as the United States (U. ...
),
Lucent Lucent Technologies, Inc., was an American Multinational corporation, multinational telecommunications equipment company headquartered in Murray Hill, New Jersey, Murray Hill, New Jersey, in the United States. It was established on September 30, 19 ...

Lucent
(now owned by
Nokia Nokia Corporation (natively Nokia , referred to as Nokia; stylized as NOKIA) is a Finnish s, , and company, founded in 1865. Nokia's main headquarters are in , , in the greater , but the company's actual roots are in the region of .
Nokia
), Nokia and
Symbol Technologies Symbol Technologies is an American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the United States The United States of America (USA), commonly known as the Unite ...
(now owned by
Zebra Technologies Zebra Technologies Corporation is an American company that manufactures and sells marking, tracking and computer printing File:Printer.ogv, A video showing an Inkjet printing, inkjet printer while printing a page. In computing, a printer is a ...
). The Wi-Fi Alliance enforces the use of the Wi-Fi brand to technologies based on the
IEEE 802.11 IEEE 802.11 is part of the IEEE 802 IEEE 802 is a family of Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers (IEEE) is a professional association for electronic engineering and electri ...
standards from the IEEE. This includes
wireless local area network A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network (LAN) within a limited area such as a home, school, computer laboratory, campus, or office building. ...
(WLAN) connections, a device to device connectivity (such as Wi-Fi Peer to Peer aka
Wi-Fi DirectWi-Fi Direct (formerly Wi-Fi Peer-to-Peer) is a Wi-Fi Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area network A local area network (LAN) is a comput ...

Wi-Fi Direct
),
Personal area network A personal area network (PAN) is a computer network A computer network is a group of computers that use a set of common communication protocols over digital signal, digital interconnections for the purpose of sharing resources located on or p ...
(PAN),
local area network A local area network (LAN) is a that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a (WAN) not only covers a larger geographic distance, but also ge ...
(LAN), and even some limited
wide area network A wide area network (WAN) is a telecommunications network A telecommunications network is a group of nodes interconnected by links that are used to exchange messages between the nodes. The links may use a variety of technologies based on t ...
(WAN) connections. Manufacturers with membership in the Wi-Fi Alliance, whose products pass the certification process, gain the right to mark those products with the Wi-Fi logo. Specifically, the certification process requires conformance to the IEEE 802.11 radio standards, the WPA and WPA2 security standards, and the EAP authentication standard. Certification may optionally include tests of IEEE 802.11 draft standards, interaction with cellular-phone technology in converged devices, and features relating to security set-up, multimedia, and power-saving. Not every Wi-Fi device is submitted for certification. The lack of Wi-Fi certification does not necessarily imply that a device is incompatible with other Wi-Fi devices. The Wi-Fi Alliance may or may not sanction derivative terms, such as Super Wi-Fi, coined by the US
Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency A regulatory agency or regulatory authority, is a Public benefit corporation Public-benefit corporation is a term that has different meanings in different jurisdictions. In ...
(FCC) to describe proposed networking in the UHF TV band in the US.


Versions and generations

Equipment frequently support multiple versions of Wi-Fi. To communicate, devices must use a common Wi-Fi version. The versions differ between the radio wavebands they operate on, the radio bandwidth they occupy, the maximum data rates they can support and other details. Some versions permit the use of multiple antennas, which permits greater speeds as well as reduced interference. Historically, the equipment has simply listed the versions of Wi-Fi using the name of the IEEE standard that it supports. In 2018, the
Wi-Fi Alliance The Wi-Fi Alliance is a non-profit organization that owns the Wi-Fi Wi-Fi () is a family of wireless network A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking is a met ...
introduced simplified Wi-Fi generational numbering to indicate equipment that supports Wi-Fi 4 (
802.11n IEEE 802.11n-2009 or 802.11n is a wireless-networking standard that uses multiple antennas to increase data rates. The Wi-Fi Alliance The Wi-Fi Alliance owns the ''Wi-Fi'' trademark A trademark (also written trade mark or trade-markThe s ...
), Wi-Fi 5 (
802.11ac IEEE 802.11ac-2013 or 802.11ac is a wireless network A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking is a method by which homes, telecommunications networks and business i ...
) and Wi-Fi 6 ( 802.11ax). These generations have a high degree of backward compatibility with previous versions. The alliance has stated that the generational level 4, 5, or 6 can be indicated in the user interface when connected, along with the signal strength. The list of most important versions of Wi-Fi is: 802.11a, 802.11b, 802.11g, 802.11n (Wi-Fi 4), 802.11h, 802.11i, 802.11-2007, 802.11-2012, 802.11ac (Wi-Fi 5), 802.11ad, 802.11af, 802.11-2016, 802.11ah, 802.11ai, 802.11aj, 802.11aq, 802.11ax (Wi-Fi 6),
802.11ayIEEE 802.11ay is a proposed enhancement to the current technical standards for Wi-Fi Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area network A local ...
.


Uses


Internet

Wi-Fi technology may be used to provide local network and
Internet access Internet access is the ability of individuals and organizations to connect to the using s, s, and other devices; and to access services such as and the . Internet access is sold by s (ISPs) delivering connectivity at a wide range of via vari ...
to devices that are within Wi-Fi range of one or more routers that are connected to the Internet. The coverage of one or more interconnected access points (''hotspots'') can extend from an area as small as a few rooms to as large as many square kilometres (miles). Coverage in the larger area may require a group of access points with overlapping coverage. For example, public outdoor Wi-Fi technology has been used successfully in
wireless mesh network A wireless mesh network (WMN) is a communications network A telecommunications network is a group of nodes In general, a node is a localized swelling (a "knot") or a point of intersection (a Vertex (graph theory), vertex). Node may refer to: I ...
s in London. An international example is
Fon Fon may refer to: Terms * Fon (title), a traditional title for a ruler in Cameroon * Fiber-optic network * Freedom of navigation * The chemistry mnemonic "List of chemistry mnemonics #Hydrogen bonds, FON", used for determining which elements hydro ...
. Wi-Fi provides services in private homes, businesses, as well as in public spaces. Wi-Fi hotspots may be set up either free-of-charge or commercially, often using a
captive portal A captive portal is a web page accessed with a web browser A web browser (commonly referred to as a browser) is application software for accessing the World Wide Web upright=1.35, A global map of the web index for countries in 2014 Th ...

captive portal
webpage for access. Organizations, enthusiasts, authorities and
business Business is the activity of making one's living or making money by producing or buying and selling products (such as goods and services). Simply put, it is "any activity or enterprise entered into for profit." Having a business name A trad ...

business
es, such as airports, hotels, and restaurants, often provide free or paid-use hotspots to attract customers, to provide services to promote business in selected areas. Routers often incorporate a
digital subscriber line Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data Digital usually refers to something using digits, particularly binary digits. Technology and computing Hardwa ...
modem or a
cable modem A cable modem is a type of network bridge A network bridge is a Networking hardware, computer networking device that creates a single, aggregate network from multiple communication networks or network segments. This function is called netwo ...
and a Wi-Fi access point, are frequently set up in homes and other buildings, to provide Internet access and
internetworking Internetworking is the practice of interconnecting multiple computer networks, such that any pair of Host (network), hosts in the connected networks can exchange messages irrespective of their hardware-level networking technology. The resulting s ...
for the structure. Similarly, battery-powered routers may include a cellular Internet
radio modem Radio modems are modems that transfer data wirelessly across a range of up to tens of kilometres. Using radio modems is a modern way to create Private Radio Networks (PRN). Private radio networks are used in critical industrial applications, when r ...
and a Wi-Fi access point. When subscribed to a cellular data carrier, they allow nearby Wi-Fi stations to access the Internet over 2G, 3G, or 4G networks using the
tethering Tethering, or phone-as-modem (PAM), is the sharing of a mobile device A mobile device (or handheld computer) is a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automat ...

tethering
technique. Many smartphones have a built-in capability of this sort, including those based on
Android Android may refer to: Science and technology * Android (robot), a humanoid robot or synthetic organism designed to imitate a human * Android (operating system), Google's mobile operating system ** Android (operating system)#Mascot, Unnamed Androi ...

Android
,
BlackBerry The blackberry is an edible fruit In botany, a fruit is the seed-bearing structure in flowering plants (also known as angiosperms) formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate seeds. Edi ...

BlackBerry
,
Bada Bada (stylized as bada; Korean Korean may refer to: People and culture * Koreans, an ethnic group originating in the Korean Peninsula * Korean cuisine * Korean culture * Korean language * Korean alphabet, or Hangul Places * Korean Peninsula, ...

Bada
,
iOS iOS (formerly iPhone OS) is a mobile operating system created and developed by Apple Inc. exclusively for its hardware. It is the operating system that powers many of the company's mobile devices, including the iPhone and iPod Touch; the t ...

iOS
,
Windows Phone Windows Phone (WP) is a discontinued family of mobile operating system A mobile operating system is an operating system for mobile phones, tablet computer, tablets, smartwatches, 2-in-1 PCs, Smart speaker, smart speakers, or other Mobile device, ...

Windows Phone
, and
Symbian Symbian is a discontinued mobile operating system (OS) and computing platform designed for smartphones. Symbian was originally developed as a proprietary software OS for Personal digital assistant, PDAs in 1998 by the Symbian Ltd. consortium. ...
, though carriers often disable the feature, or charge a separate fee to enable it, especially for customers with unlimited data plans. "Internet packs" provide standalone facilities of this type as well, without the use of a smartphone; examples include the
MiFi MiFi is a brand name used to describe a wireless router that acts as a mobile Hotspot (Wi-Fi), Wi-Fi hotspot. In many countries, including the United States, Canada, and Mexico, Inseego Corp (previously known as Novatel Wireless) owns a registe ...
- and
WiBro WiBro (''wireless broadband'') is a wireless broadband Internet technology developed by the South Korean telecoms industry. WiBro is the South Korean service name for Institute of Electrical and Electronics Engineers, IEEE 802.16e (mobile WiMAX ...
-branded devices. Some laptops that have a cellular modem card can also act as mobile Internet Wi-Fi access points. Many traditional university campuses in the developed world provide at least partial Wi-Fi coverage.
Carnegie Mellon University Carnegie Mellon University (CMU) is a private Private or privates may refer to: Music * "In Private "In Private" was the third single in a row to be a charting success for United Kingdom, British singer Dusty Springfield, after an absence ...
built the first campus-wide wireless Internet network, called Wireless Andrew, at its
Pittsburgh Pittsburgh ( ) is a city in the Commonwealth (U.S. state), Commonwealth of Pennsylvania in the United States and the county seat of Allegheny County, Pennsylvania, Allegheny County. A population of 302,971 residents lives within the city limit ...

Pittsburgh
campus in 1993 before Wi-Fi branding originated. By February 1997, the CMU Wi-Fi zone was fully operational. Many universities collaborate in providing Wi-Fi access to students and staff through the
Eduroam eduroam (''edu''cation ''roam''ing) is an international roaming Roaming is a wireless Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points that do not use an electri ...
international authentication infrastructure.


City-wide

In the early 2000s, many cities around the world announced plans to construct citywide Wi-Fi networks. There are many successful examples; in 2004,
Mysore Mysore (), officially Mysuru (; Kannada: ಮೈಸೂರು), is a city in the southern part of the state of Karnataka, India. Mysore city is geographically located between 12° 18′ 26″ north latitude and 76° 38′ 59″ east longitude. I ...

Mysore
(Mysuru) became India's first Wi-Fi-enabled city. A company called WiFiyNet has set up hotspots in Mysore, covering the whole city and a few nearby villages. In 2005, St. Cloud, Florida and
Sunnyvale, California Sunnyvale () is a city located in the Santa Clara Valley in northwest Santa Clara County, California, Santa Clara County, California. Sunnyvale lies along the historic El Camino Real (California), El Camino Real and U.S. Route 101 in Californi ...
, became the first cities in the United States to offer citywide free Wi-Fi (from MetroFi).
Minneapolis Minneapolis () is a city in the U.S. state of Minnesota. With a population of 429,954 as of 2020 United States census, 2020, it is the most populous city in the state and the 46th most populous in the nation. The county seat of Hennepin County, ...

Minneapolis
has generated $1.2 million in profit annually for its provider. In May 2010, the then
London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has b ...

London
mayor
Boris Johnson Alexander Boris de Pfeffel Johnson (; born 19 June 1964) is a British politician and writer serving as Prime Minister of the United Kingdom The prime minister of the United Kingdom is the head of government The head of government ...

Boris Johnson
pledged to have London-wide Wi-Fi by 2012. Several
boroughs A borough is an administrative division Administrative division, administrative unitArticle 3(1). , country subdivision, administrative region, subnational entity, first-level subdivision, as well as many similar terms, are generic names for ...

boroughs
including
Westminster Westminster is a district in Central London Central London is the innermost part of London London is the capital city, capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom. The city sta ...

Westminster
and
Islington Islington () is a district in Greater London, England, and part of the London Borough of Islington. It is a mainly residential district of Inner London, extending from Islington's Islington#Islington High Street, High Street to Highbury Fields, ...
already had extensive outdoor Wi-Fi coverage at that point.
New York City New York, often called New York City to distinguish it from New York State New York is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of ...

New York City
announced a city-wide campaign to convert old into digitized "kiosks" in 2014. The project, titled , has created a network of kiosks which serve as public WiFi hotspots, high-definition screens and
landlines Image:Siemens Euroset 805.jpg, upright=1.3, A landline telephone made by Siemens A landline telephone (also known as land line, land-line, main line, home phone, landline, fixed-line, and wireline) is a telephone, phone that uses a wire, metal w ...
. Installation of the screens began in late 2015. The city government plans to implement more than seven thousand kiosks over time, eventually making LinkNYC the largest and fastest public, government-operated Wi-Fi network in the world. The has planned a similar project across major cities of the country, with the project's first implementation in the
Camden Camden may refer to: People * Camden (surname), a surname of English origin * Camden Joy (born 1964), American writer * Camden Toy (born 1957), American actor Places Australia * Camden, New South Wales * Camden, Rosehill, a heritage-listed ...
borough of
London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has b ...

London
. Officials in South Korea's capital
Seoul Seoul (, like ''soul''; ko, 서울 ; ), officially the Seoul Special City, is the capital Capital most commonly refers to: * Capital letter Letter case (or just case) is the distinction between the letters that are in larger uppe ...

Seoul
are moving to provide free Internet access at more than 10,000 locations around the city, including outdoor public spaces, major streets, and densely populated residential areas. Seoul will grant leases to KT, Telecom, and SK Telecom. The companies will invest $44 million in the project, which was to be completed in 2015.


Geolocation

Wi-Fi positioning system Wi-Fi positioning system (WPS, also abbreviated as WiPS or WFPS) is a geolocation Geopositioning, also known as geotracking, geolocalization, geolocating, geolocation, or geoposition fixing is the process of determining or estimating the geograph ...
s use the positions of Wi-Fi hotspots to identify a device's location.


Motion detection

Wi-Fi sensing is used in applications such as
motion detection Motion detection is the process of detecting a change in the position of an object relative to its surroundings or a change in the surroundings relative to an object. It can be achieved by either mechanical Mechanical may refer to: Machine * Mecha ...
and
gesture recognition A gesture is a form of non-verbal communication or non-vocal communication Communication (from Latin ''communicare'', meaning "to share") is the act of developing Semantics, meaning among Subject (philosophy), entities or Organization, gro ...

gesture recognition
.


Operational principles

Wi-Fi stations communicate by sending each other
data packet In telecommunications and computer networking, a network packet is a formatted unit of Data (computing), data carried by a packet-switched network. A packet consists of control information and user data; the latter is also known as the ''Payload ...
s: blocks of data individually sent and delivered over radio. As with all radio, this is done by the of
carrier wave upright=1.4, The frequency spectrum of a typical radio signal from an AM or FM radio transmitter. The horizontal axis is frequency; the vertical axis is signal amplitude or power. It consists of a signal (C) at the carrier wave frequency ''f''C, wi ...
s. Different versions of Wi-Fi use different techniques, 802.11b uses
DSSS In telecommunication Telecommunication is the transmission of information Information can be thought of as the resolution of uncertainty; it answers the question of "What an entity is" and thus defines both its essence and the nature ...
on a single carrier, whereas 802.11a, Wi-Fi 4, 5 and 6 use multiple carriers on slightly different frequencies within the channel (
OFDM In telecommunications, orthogonal frequency-division multiplexing (OFDM) is a type of digital transmission Digital usually refers to something using digits, particularly binary digits. Technology and computing Hardware *Digital electronics Di ...
). As with other IEEE 802 LANs, stations come programmed with a globally unique 48-bit MAC address (often printed on the equipment) so that each Wi-Fi station has a unique address. The MAC addresses are used to specify both the destination and the source of each data packet. Wi-Fi establishes link-level connections, which can be defined using both the destination and source addresses. On the reception of a transmission, the receiver uses the destination address to determine whether the transmission is relevant to the station or should be ignored. A network interface normally does not accept packets addressed to other Wi-Fi stations. Due to the ubiquity of Wi-Fi and the ever-decreasing cost of the hardware needed to support it, many manufacturers now build Wi-Fi interfaces directly into
PC motherboard A motherboard (also called mainboard, main circuit board, system board, baseboard, planar board, logic board, or mobo) is the main printed circuit board A printed circuit board (PCB) mechanically supports and electrically connects electrica ...
s, eliminating the need for installation of a separate wireless network card. Channels are used
half duplex A duplex communication system 400px, Communication system A communications system or communication system is a collection of individual telecommunications network A telecommunications network is a group of nodes interconnected by links ...
and can be time-shared by multiple networks. When communication happens on the same channel, any information sent by one computer is locally received by all, even if that information is intended for just one destination. The network interface card interrupts the
CPU A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuit File:PExdcr01CJC.jpg, 200px, A circuit built on a printed circuit board (PCB). An electronic circuit is composed of ...

CPU
only when applicable packets are received: the card ignores information not addressed to it. The use of the same channel also means that the data bandwidth is shared, such that, for example, available data bandwidth to each device is halved when two stations are actively transmitting. A scheme known as
carrier sense multiple access with collision avoidance Carrier-sense multiple access with collision avoidance (CSMA/CA) in computer network A computer network is a group of computers that use a set of common communication protocols over digital signal, digital interconnections for the purpose of ...
(CSMA/CA) governs the way stations share channels. With CSMA/CA stations attempt to avoid collisions by beginning transmission only after the channel is sensed to be "idle", but then transmit their packet data in its entirety. However, for geometric reasons, it cannot completely prevent collisions. A collision happens when a station receives multiple signals on a channel at the same time. This corrupts the transmitted data and can require stations to re-transmit. The lost data and re-transmission reduces throughput, in some cases severely.


Waveband

The 802.11 standard provides several distinct
radio frequency Radio frequency (RF) is the oscillation Oscillation is the repetitive variation, typically in time Time is the indefinite continued sequence, progress of existence and event (philosophy), events that occur in an apparently irreversible p ...
ranges for use in Wi-Fi communications: 900 
MHz The hertz (symbol: Hz) is the derived unit of frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also referred to as temporal frequency, which emphasizes the contrast to spatial frequency and an ...

MHz
, 2.4 GHz, 3.6 GHz, 4.9 GHz, 5 GHz, 5.9 GHz and 60 GHz
bands Band or BAND may refer to: Places *Bánd, a village in Hungary *Band, Iran, a village in Urmia County, West Azerbaijan Province, Iran *Band, Mureș, a commune in Romania *Band-e Majid Khan, a village in Bukan County, West Azerbaijan Province, Ira ...
. Each range is divided into a multitude of
channels Channel, channels, channeling, etc., may refer to: Geography * Channel (geography), in physical geography, a landform consisting of the outline (banks) of the path of a narrow body of water. Australia * Channel Country, region of outback Austr ...
. In the standards, channels are numbered at 5 MHz spacing within a band (except in the 60 GHz band, where they are 2.16 GHz apart), and the number refers to the centre frequency of the channel. Although channels are numbered at 5 MHz spacing, transmitters generally occupy at least 20 MHz, and standards allow for channels to be bonded together to form wider channels for higher throughput. Countries apply their own regulations to the allowable channels, allowed users and maximum power levels within these frequency ranges. The "ISM" band ranges are also often improperly used because some do not know the difference between Part 15 and Part 18 of the FCC rules. 802.11b/g/n can use the 2.4 GHz Part 15 band, operating in the United States under
Part 15 Code of Federal Regulations The ''Code of Federal Regulations'' (''CFR'') is the codification of the general and permanent regulations published in the ''Federal Register The ''Federal Register'' (FR or sometimes Fed. Reg.) is the official jo ...
Rules and Regulations. In this frequency band equipment may occasionally suffer
interference Interference is the act of interfering, invading, or poaching. Interference may also refer to: Communications * Interference (communication), anything which alters, modifies, or disrupts a message * Adjacent-channel interference, caused by extran ...
from
microwave oven A microwave oven (commonly referred to as a microwave) is an electric oven upA double oven A ceramic oven An oven is a tool A tool is an object that can extend an individual's ability to modify features of the surrounding environment. ...

microwave oven
s,
cordless telephone A cordless telephone or portable telephone is a telephone A telephone is a telecommunications Appliance (disambiguation), device that permits two or more users to conduct a conversation when they are too far apart to be heard directly. A ...
s,
USB 3.0 USB 3.0, released in November 2008, is the third major version of the Universal Serial Bus (USB) standard for interfacing computers and electronic devices. Among other improvements, USB 3.0 adds the new transfer rate referred to as ''S ...

USB 3.0
hubs, and
Bluetooth Bluetooth is a short-range wireless Wireless communication (or just wireless, when the context allows) is the telecommunication, transfer of information between two or more points that do not use an electrical conductor as a medium by which ...

Bluetooth
devices. Spectrum assignments and operational limitations are not consistent worldwide: Australia and Europe allow for an additional two channels (12, 13) beyond the 11 permitted in the United States for the 2.4 GHz band, while Japan has three more (12–14). In the US and other countries, 802.11a and 802.11g devices may be operated without a licence, as allowed in Part 15 of the FCC Rules and Regulations. 802.11a/h/j/n/ac/ax can use the 5 GHz U-NII band, which, for much of the world, offers at least 23 non-overlapping 20  MHz channels rather than the 2.4 GHz frequency band, where the channels are only 5 MHz wide. In general, lower frequencies have better range but have less capacity. The 5 GHz bands are absorbed to a greater degree by common building materials than the 2.4 GHz bands and usually give a shorter range. As 802.11 specifications evolved to support higher throughput, the protocols have become much more efficient in their use of bandwidth. Additionally, they have gained the ability to aggregate (or 'bond') channels together to gain still more throughput where the bandwidth is available. 802.11n allows for double radio spectrum/bandwidth (40 MHz- 8 channels) compared to
802.11a IEEE 802.11a-1999 or 802.11a was an amendment to the IEEE 802.11 (legacy mode), IEEE 802.11 wireless local network specifications that defined requirements for an orthogonal frequency division multiplexing (OFDM) communication system. It was origina ...
or 802.11g (20 MHz). 802.11n can also be set to limit itself to 20 MHz bandwidth to prevent interference in dense communities. In the 5 GHz band, 20 MHz, 40 MHz, 80 MHz, and 160 MHz bandwidth signals are permitted with some restrictions, giving much faster connections.


Communication stack

Wi-Fi is part of the IEEE 802 protocol family. The data is organized into 802.11 frames that are very similar to
Ethernet frame In computer networking, an Ethernet frame is a data link layer protocol data unit and uses the underlying Ethernet physical layer transport mechanisms. In other words, a network packet, data unit on an Ethernet link transports an Ethernet frame a ...

Ethernet frame
s at the data link layer, but with extra address fields. MAC addresses are used as
network address A network address is an identifier for a node In general, a node is a localized swelling (a "knot A knot is an intentional complication in Rope, cordage which may be practical or decorative, or both. Practical knots are classified by function, ...
es for routing over the LAN. Wi-Fi's MAC and
physical layer In the seven-layer OSI model The Open Systems Interconnection model (OSI model) is a that characterises and standardises the communication functions of a or computing system without regard to its underlying internal structure and technolo ...
(PHY) specifications are defined by IEEE 802.11 for modulating and receiving one or more carrier waves to transmit the data in the infrared, and 2.4, 3.6, 5, or 60 GHz frequency bands. They are created and maintained by the IEEE LAN/
MAN A man is an adult male Male (♂) is the sex of an organism that produces the gamete known as sperm. A male gamete can fuse with a larger female gamete, or ovum, in the process of fertilization. A male cannot sexual reproduction, reproduc ...
Standards Committee (
IEEE 802 IEEE 802 is a family of Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers (IEEE) is a professional association for electronic engineering and electrical engineering (and associated disciplin ...

IEEE 802
). The base version of the standard was released in 1997 and has had many 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. As a result, in the market place, each revision tends to become its own standard. In addition to 802.11 the IEEE 802 protocol family has specific provisions for Wi-Fi. These are required because Ethernet's cable-based media are not usually shared, whereas with wireless all transmissions are received by all stations within the range that employ that radio channel. While Ethernet has essentially negligible error rates, wireless communication media are subject to significant interference. Therefore, the accurate transmission is not guaranteed so delivery is, therefore, a
best-effort delivery Best-effort delivery describes a network service in which the network Network and networking may refer to: Arts, entertainment, and media * ''Network'' (1976 film), a 1976 American film * ''Network'' (2019 film), an Indian film * ''Network'' ( ...
mechanism. Because of this, for Wi-Fi, the
Logical Link Control {{OSI model , data In the IEEE 802 IEEE 802 is a family of Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers (IEEE) is a professional association for electronic engineering and electrical ...
(LLC) specified by
IEEE 802.2 IEEE 802.2 is the original name of the ISO/IEC 8802-2 standard Standard may refer to: Flags * Colours, standards and guidons * Standard (flag), a type of flag used for personal identification Norm, convention or requirement * Standard (metro ...
employs Wi-Fi's
media access control In IEEE 802, IEEE 802 LAN/MAN standards, the medium access control (MAC, also called media access control) sublayer is the layer that controls the hardware responsible for interaction with the wired, optical or wireless transmission medium. The MA ...
(MAC) protocols to manage retries without relying on higher levels of the protocol stack. For internetworking purposes, Wi-Fi is usually layered as a
link layer In computer networking, the link layer is the lowest Abstraction layer, layer in the Internet protocol suite, the networking architecture of the Internet. The link layer is the group of methods and communications protocols confined to the link th ...
(equivalent to the physical and data link layers of the
OSI model The Open Systems Interconnection model (OSI model) is a that characterises and standardises the communication functions of a or computing system without regard to its underlying internal structure and technology. Its goal is the interoperabil ...

OSI model
) below the
internet layer The internet layer is a group of internetworking methods, protocols, and specifications in the Internet protocol suite that are used to transport network packets from the originating host across network boundaries; if necessary, to the destin ...
of the
Internet Protocol The Internet Protocol (IP) is the network layer In the seven-layer OSI model The Open Systems Interconnection model (OSI model) is a conceptual model A conceptual model is a representation of a system, made of the composition of concept C ...
. This means that nodes have an associated
internet address An Internet Protocol address (IP address) is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication.RFC 760, ''DOD Standard Internet Protocol'', DARPA, Information Sciences In ...
and, with suitable connectivity, this allows full Internet access.


Modes


Infrastructure

In infrastructure mode, which is the most common mode used, all communications go through a base station. For communications within the network, this introduces an extra use of the airwaves but has the advantage that any two stations that can communicate with the base station can also communicate through the base station, which enormously simplifies the protocols.


Ad hoc and Wi-Fi direct

Wi-Fi also allows communications directly from one computer to another without an access point intermediary. This is called ''ad hoc'' Wi-Fi transmission. Different types of ad hoc networks exist. In the simplest case network nodes must talk directly to each other. In more complex protocols nodes may forward packets, and nodes keep track of how to reach other nodes, even if they move around. Ad hoc mode was first described by
Chai Keong Toh Chai Keong Toh is a Singaporean computer scientist, engineer, professor, and Chief Engineering and Technology Officer. He has performed research on wireless ad hoc networks, mobile computing, Internet Protocols, and multimedia for over two deca ...
in his 1996 patent of wireless ad hoc routing, implemented on Lucent WaveLAN 802.11a wireless on IBM
ThinkPad#REDIRECT ThinkPad ThinkPad is a line of business-oriented laptop computers and tablets designed, developed and marketed by Lenovo Lenovo Group Limited, often shortened to Lenovo ( ), is a Chinese multinational corporation, multinational t ...

ThinkPad
s over a size nodes scenario spanning a region of over a mile. The success was recorded in ''Mobile Computing'' magazine (1999) and later published formally in ''
IEEE Transactions on Wireless Communications ''IEEE Transactions on Wireless Communications'' is a monthly peer-reviewed scientific journal published by the IEEE Communications Society. It covers all areas of wireless communication systems and networks. It was established in 2002 and the edito ...
'', 2002 and ''ACM SIGMETRICS Performance Evaluation Review'', 2001. This wireless ad hoc network mode has proven popular with
multiplayer A multiplayer video game is a in which more than one person can play in the same game environment at the same time, either locally and on the same computing system (e.g. '), locally and on different computing systems via a , or via a , most comm ...
handheld game console A handheld game console, or simply handheld console, is a small, portable self-contained video game console A video game console is an electronic device that output Output may refer to: * The information produced by a computer, see Input/out ...

handheld game console
s, such as the
Nintendo DS The is a handheld game console produced by Nintendo, released globally across 2004 and 2005. The DS, an initialism for "Developers' System" or "Dual Screen", introduced distinctive new features to handheld games: two LCD screens working in tand ...

Nintendo DS
,
PlayStation Portable The PlayStation Portable (PSP) is a developed and marketed by . It was first released in on December 12, 2004, in on March 24, 2005, and in s on September 1, 2005, and is the first handheld installment in the line of consoles. As a , the P ...

PlayStation Portable
,
digital camera A digital camera is a camera A camera is an optical Optics is the branch of physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behav ...

digital camera
s, and other
consumer electronics Consumer electronics or home electronics are electronic Electronic may refer to: *Electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum ...
devices. Some devices can also share their Internet connection using ad hoc, becoming hotspots or "virtual routers". Similarly, the Wi-Fi Alliance promotes the specification
Wi-Fi DirectWi-Fi Direct (formerly Wi-Fi Peer-to-Peer) is a Wi-Fi Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area network A local area network (LAN) is a comput ...

Wi-Fi Direct
for file transfers and media sharing through a new discovery- and security-methodology. Wi-Fi Direct launched in October 2010. Another mode of direct communication over Wi-Fi is Tunneled Direct-Link Setup (), which enables two devices on the same Wi-Fi network to communicate directly, instead of via the access point.


Multiple access points

An
Extended Service Set In IEEE 802.11 wireless LAN, wireless local area networking standards (including Wi-Fi), a service set is a group of wireless network devices which share a ''service set identifier'' (''SSID'')—typically the natural language label that users see ...
may be formed by deploying multiple access points that are configured with the same SSID and security settings. Wi-Fi client devices typically connect to the access point that can provide the strongest signal within that service set. Increasing the number of Wi-Fi access points for a network provides redundancy, better range, support for fast roaming, and increased overall network-capacity by using more channels or by defining smaller
cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Closed spaces * Monastic cell, a small room, hut, or cave in which a monk or religious recluse lives * Prison cell, a room used to hold peopl ...
. Except for the smallest implementations (such as home or small office networks), Wi-Fi implementations have moved toward "thin" access points, with more of the network intelligence housed in a centralized network appliance, relegating individual access points to the role of "dumb" transceivers. Outdoor applications may use
mesh A mesh is a barrier made of connected strands of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearan ...
topologies.


Performance

Wi-Fi operational range depends on factors such as the frequency band, radio power output, receiver sensitivity, antenna gain, and antenna type as well as the modulation technique. Also, the propagation characteristics of the signals can have a big impact. At longer distances, and with greater signal absorption, speed is usually reduced.


Transmitter power

Compared to cell phones and similar technology, Wi-Fi transmitters are low-power devices. In general, the maximum amount of power that a Wi-Fi device can transmit is limited by local regulations, such as FCC Part 15 in the US. Equivalent isotropically radiated power (EIRP) in the European Union is limited to 20
dBm dBm or dBmW (decibel-milliwatts) is a unit of level Level or levels may refer to: Engineering * Level (instrument), a device used to measure true horizontal or relative heights *Canal pound or level *Regrading or levelling, the process of rais ...
(100 mW). To reach requirements for wireless LAN applications, Wi-Fi has higher power consumption compared to some other standards designed to support wireless personal area network (PAN) applications. For example, Bluetooth provides a much shorter propagation range between 1 and 100 metres (1 and 100 yards) and so in general has a lower power consumption. Other low-power technologies such as
ZigBee Zigbee is an IEEE 802.15.4-based specification A specification often refers to a set of documented requirements to be satisfied by a material, design, product, or service. A specification is often a type of technical standard A technical sta ...
have fairly long range, but much lower data rate. The high power consumption of Wi-Fi makes battery life in some mobile devices a concern.


Antenna

An access point compliant with either
802.11b IEEE 802.11b-1999 or 802.11b is an amendment to the IEEE 802.11 IEEE 802.11 is part of the IEEE 802 IEEE 802 is a family of Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers (IEEE) is a ...
or 802.11g, using the stock
omnidirectional antenna on a walkie-talkie A walkie-talkie, more formally known as a handheld transceiver (HT), is a hand-held, portable, two-way radio transceiver. Its development during the Second World War has been variously credited to Donald Hings, radio enginee ...
might have a range of . The same radio with an external semi parabolic antenna (15 dB gain) with a similarly equipped receiver at the far end might have a range over 20 miles. Higher gain rating (dBi) indicates further deviation (generally toward the horizontal) from a theoretical, perfect
isotropic radiator An isotropic radiator is a theoretical point source of electromagnetic wave, electromagnetic or sound waves which radiates the same intensity of radiation in all directions. It has no preferred direction of radiation. It radiates uniformly in ...
, and therefore the antenna can project or accept a usable signal further in particular directions, as compared to a similar output power on a more isotropic antenna. For example, an 8 dBi antenna used with a 100 mW driver has a similar horizontal range to a 6 dBi antenna being driven at 500 mW. Note that this assumes that radiation in the vertical is lost; this may not be the case in some situations, especially in large buildings or within a
waveguide A waveguide is a structure that guides waves, such as electromagnetic waves or sound In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is ...

waveguide
. In the above example, a directional waveguide could cause the low-power 6 dBi antenna to project much further in a single direction than the 8 dBi antenna, which is not in a waveguide, even if they are both driven at 100 mW. On wireless routers with detachable antennas, it is possible to improve range by fitting upgraded antennas that provide a higher gain in particular directions. Outdoor ranges can be improved to many kilometres (miles) through the use of high gain
directional antenna A directional antenna or beam antenna is an antenna which radiates or receives greater power in specific directions allowing increased performance and reduced Interference (communication), interference from unwanted sources. Directional antennas p ...
s at the router and remote device(s).


MIMO (multiple-input and multiple-output)

Wi-Fi 4 and higher standards allow devices to have multiple antennas on transmitters and receivers. Multiple antennas enable the equipment to exploit
multipath propagation In radio communication, multipath is the propagation phenomenon that results in radio Radio is the technology of signaling and telecommunication, communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30& ...
on the same frequency bands giving much faster speeds and greater range. Wi-Fi 4 can more than double the range over previous standards. The Wi-Fi 5 standard uses the 5 GHz band exclusively, and is capable of multi-station WLAN throughput of at least 1 gigabit per second, and a single station throughput of at least 500 Mbit/s. As of the first quarter of 2016, The Wi-Fi Alliance certifies devices compliant with the 802.11ac standard as "Wi-Fi CERTIFIED ac". This standard uses several signal processing techniques such as multi-user MIMO and 4X4 Spatial Multiplexing streams, and wide channel bandwidth (160 MHz) to achieve its gigabit throughput. According to a study by IHS Technology, 70% of all access point sales revenue in the first quarter of 2016 came from 802.11ac devices.


Radio propagation

With Wi-Fi signals line-of-sight usually works best, but signals can transmit, absorb, reflect,
refract In physics, refraction is the change in direction of a wave In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that ...

refract
, and through and around structures, both man-made and natural. Wi-Fi signals are very strongly affected by metallic structures (including
rebar Rebar (short for reinforcing bar), known when massed as reinforcing steel or reinforcement steel, is a steel bar or mesh of steel wires used as a tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the con ...
in concrete, low-e coatings in glazing) and water (such as found in vegetation.) Due to the complex nature of radio propagation at typical Wi-Fi frequencies, particularly around trees and buildings, algorithms can only approximately predict Wi-Fi signal strength for any given area in relation to a transmitter. This effect does not apply equally to long-range Wi-Fi, since longer links typically operate from towers that transmit above the surrounding foliage. Mobile use of Wi-Fi over wider ranges is limited, for instance, to uses such as in an automobile moving from one hotspot to another. Other wireless technologies are more suitable for communicating with moving vehicles. ;Distance records Distance records (using non-standard devices) include in June 2007, held by Ermanno Pietrosemoli and EsLaRed of Venezuela, transferring about 3 MB of data between the mountain-tops of El Águila and Platillon. The Swedish Space Agency transferred data , using 6 watt amplifiers to reach an overhead stratospheric balloon.


Interference

Wi-Fi connections can be blocked or the Internet speed lowered by having other devices in the same area. Wi-Fi protocols are designed to share the wavebands reasonably fairly, and this often works with little to no disruption. To minimize collisions with Wi-Fi and non-Wi-Fi devices, Wi-Fi employs
Carrier-sense multiple access with collision avoidance Carrier-sense multiple access with collision avoidance (CSMA/CA) in computer network A computer network is a group of computers that use a set of common communication protocols over digital signal, digital interconnections for the purpose of ...
(CSMA/CA), where transmitters listen before transmitting and delay transmission of packets if they detect that other devices are active on the channel, or if noise is detected from adjacent channels or non-Wi-Fi sources. Nevertheless, Wi-Fi networks are still susceptible to the
hidden node In wireless networking, the hidden node problem or hidden terminal problem occurs when a Node (networking), node can communicate with a wireless access point (AP), but cannot directly communicate with other nodes that are communicating with that A ...
and
exposed node problemImage:Exposed terminal problem.svg, 400px In wireless networks, the exposed node problem occurs when a node is prevented from sending packets to other nodes because of co-channel interference with a neighboring transmitter. Consider an example of fo ...
. A standard speed Wi-Fi signal occupies five channels in the 2.4 GHz band. Interference can be caused by overlapping channels. Any two channel numbers that differ by five or more, such as 2 and 7, do not overlap (no
adjacent-channel interference Adjacent-channel interference (ACI) is interference caused by extraneous power Power typically refers to: * Power (physics) In physics, power is the amount of energy transferred or converted per unit time. In the International System of Units, ...
). The oft-repeated adage that channels 1, 6, and 11 are the ''only'' non-overlapping channels is, therefore, not accurate. Channels 1, 6, and 11 are the only ''group of three'' non-overlapping channels in North America. However, whether the overlap is significant depends on physical spacing. Channels that are four apart interfere a negligible amount-much less than reusing channels (which causes
co-channel interference Co-channel interference or CCI is crosstalk In electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matter. It uses active devices ...
)-if transmitters are at least a few metres (yards) apart.Effect of adjacent-channel interference in IEEE 802.11 WLANs - Eduard Garcia Villegas, Elena Lopez-Aguilera, Rafael Vidal, Josep Paradells (2007) In Europe and Japan where channel 13 is available, using Channels 1, 5, 9, and 13 for 802.11g and
802.11n IEEE 802.11n-2009 or 802.11n is a wireless-networking standard that uses multiple antennas to increase data rates. The Wi-Fi Alliance The Wi-Fi Alliance owns the ''Wi-Fi'' trademark A trademark (also written trade mark or trade-markThe s ...
is recommended. However, many 2.4 GHz 802.11b and 802.11g access-points default to the same channel on initial startup, contributing to congestion on certain channels. Wi-Fi pollution, or an excessive number of access points in the area, can prevent access and interfere with other devices' use of other access points as well as with decreased
signal-to-noise ratio Signal-to-noise ratio (SNR or S/N) is a measure used in science and engineering Engineering is the use of scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and ...
(SNR) between access points. These issues can become a problem in high-density areas, such as large apartment complexes or office buildings with many Wi-Fi access points. Other devices use the 2.4 GHz band: microwave ovens, ISM band devices,
security camera Security is freedom from, or resilience against, potential harm (or other unwanted Coercion, coercive change) caused by others. Beneficiaries (technically referents) of security may be of persons and social groups, objects and institutions, ecosyst ...

security camera
s, ZigBee devices, Bluetooth devices, video senders, cordless phones,
baby monitor 230px, Audio baby monitor A baby monitor, also known as a baby alarm, is a radio system used to remotely listen to sounds made by an infant. An audio monitor consists of a transmitter unit, equipped with a microphone, placed near to the child. It t ...
s, and, in some countries,
amateur radio Amateur radio, also known as ham radio, is the use of radio frequency radio spectrum, spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emerge ...
, all of which can cause significant additional interference. It is also an issue when municipalities or other large entities (such as universities) seek to provide large area coverage. On some 5 GHz bands interference from radar systems can occur in some places. For base stations that support those bands they employ Dynamic Frequency Selection which listens for radar, and if it is found, it will not permit a network on that band. These bands can be used by low power transmitters without a licence, and with few restrictions. However, while unintended interference is common, users that have been found to cause deliberate interference (particularly for attempting to locally monopolize these bands for commercial purposes) have been issued large fines.


Throughput

Various layer 2 variants of IEEE 802.11 have different characteristics. Across all flavours of 802.11, maximum achievable throughputs are either given based on measurements under ideal conditions or in the layer 2 data rates. This, however, does not apply to typical deployments in which data are transferred between two endpoints of which at least one is typically connected to a wired infrastructure, and the other is connected to an infrastructure via a wireless link. This means that typically data frames pass an 802.11 (WLAN) medium and are being converted to 802.3 (Ethernet) or vice versa. Due to the difference in the frame (header) lengths of these two media, the packet size of an application determines the speed of the data transfer. This means that an application that uses small packets (e.g., VoIP) creates a data flow with high overhead traffic (low
goodput In computer networks, goodput (a of and ) is the throughput of a communication; i.e. the number of useful information s delivered by the network to a certain destination per unit of time. The amount of data considered excludes bits as well as ...
). Other factors that contribute to the overall application data rate are the speed with which the application transmits the packets (i.e., the data rate) and the energy with which the wireless signal is received. The latter is determined by distance and by the configured output power of the communicating devices. The same references apply to the attached throughput graphs, which show measurements of
UDP UDP may refer to: Political parties * Ulster Democratic Party, in Northern Ireland * ''União Democrática Popular'' (People's Democratic Union (Portugal)) * ''Unidad Democrática y Popular'' (Democratic and Popular Union), a former Bolivian umbr ...
throughput measurements. Each represents an average throughput of 25 measurements (the error bars are there, but barely visible due to the small variation), is with specific packet size (small or large), and with a specific data rate (10 kbit/s – 100 Mbit/s). Markers for traffic profiles of common applications are included as well. This text and measurements do not cover packet errors but information about this can be found at the above references. The table below shows the maximum achievable (application-specific) UDP throughput in the same scenarios (same references again) with various WLAN (802.11) flavours. The measurement hosts have been 25 metres (yards) apart from each other; loss is again ignored.


Hardware

Wi-Fi allows wireless deployment of local area networks (LANs). Also, spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs. However, building walls of certain materials, such as stone with high metal content, can block Wi-Fi signals. A Wi-Fi device is a short-range
wireless Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points that do not use an electrical conductor In physics Physics (from grc, φυσική (ἐπιστήμη), ph ...

wireless
device. Wi-Fi devices are fabricated on
RF CMOSRF CMOS is a metal–oxide–semiconductor The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET), also known as the metal–oxide–silicon transistor (MOS transistor, or MOS), is a type of insulated-gate field-e ...
integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuit 200px, A circuit built on a printed circuit board (PCB). An electronic circuit is composed of indiv ...

integrated circuit
(
RF circuit Radio-frequency (RF) engineering is a subset of electronic engineering Printed circuit board Electronic engineering (also called electronics and communications engineering) is an electrical engineering discipline which utilizes nonlinear and ...
) chips. Since the early 2000s, manufacturers are building wireless network adapters into most laptops. The price of
chipset In a computer system, a chipset is a set of electronic components An electronic component is any basic discrete device or physical entity in an electronic system used to affect electrons or their associated fields. Electronic components ar ...

chipset
s for Wi-Fi continues to drop, making it an economical networking option included in ever more devices. Different competitive brands of access points and client network-interfaces can inter-operate at a basic level of service. Products designated as "Wi-Fi Certified" by the Wi-Fi Alliance are
backward compatible Backward or Backwards is a relative direction Body relative directions (also known as egocentric coordinates) are geometrical orientations relative to a body such as a human Humans (''Homo sapiens'') are the most populous and widespre ...
. Unlike
mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, or hand phone, sometimes shortened to simply mobile, cell or just phone, is a portable telephone A telephone is a telecommunications device that permits two or more use ...

mobile phone
s, any standard Wi-Fi device works anywhere in the world.


Access point

A wireless access point (WAP) connects a group of wireless devices to an adjacent wired LAN. An access point resembles a
network hub In network science, a hub is a Node (networking), node with a number of links that greatly exceeds the average. Emergence of hubs is a consequence of a scale-free property of networks. While hubs cannot be observed in a random network, they are exp ...

network hub
, relaying
data Data (; ) are individual facts, statistics, or items of information, often numeric. In a more technical sense, data are a set of values of qualitative property, qualitative or quantity, quantitative variable (research), variables about one or ...
between connected wireless devices in addition to a (usually) single connected wired device, most often an Ethernet hub or switch, allowing wireless devices to communicate with other wired devices.


Wireless adapter

Wireless adapters allow devices to connect to a wireless network. These adapters connect to devices using various external or internal interconnects such as PCI, miniPCI, USB,
ExpressCard ExpressCard, initially called NEWCARD, is an interface to connect peripheral, peripheral devices to a computer, usually a laptop, laptop computer. The ExpressCard technical standard specifies the design of slots built into the computer and of expa ...
, Cardbus, and
PC Card In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and softw ...

PC Card
. As of 2010, most newer laptop computers come equipped with built-in internal adapters.


Router

Wireless router A wireless router is a device that performs the functions of a Router (computing), router and also includes the functions of a wireless access point. It is used to provide access to the Internet or a Private network, private computer network. Dep ...

Wireless router
s integrate a Wireless Access Point, Ethernet
switch In , a switch is an that can disconnect or connect the conducting path in an , interrupting the or diverting it from one conductor to another. The most common type of switch is an electromechanical device consisting of one or more sets of movab ...

switch
, and internal router firmware application that provides IP
routing Routing is the process of selecting a path for traffic in a network Network, networking and networked may refer to: Science and technology * Network theory Network theory is the study of Graph (discrete mathematics), graphs as a represen ...

routing
, NAT, and
DNS The Domain Name System (DNS) is the hierarchical and decentralized Decentralization or decentralisation is the process by which the activities of an organization, particularly those regarding planning and decision making, are distributed or ...

DNS
forwarding through an integrated WAN-interface. A wireless router allows wired and wireless Ethernet LAN devices to connect to a (usually) single WAN device such as a cable modem,
DSL modem A digital subscriber line Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data Digital usually refers to something using digits, particularly binary digits. ...
, or optical modem. A wireless router allows all three devices, mainly the access point and router, to be configured through one central utility. This utility is usually an integrated
web server A web server is computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operations known as Computer program, pr ...
that is accessible to wired and wireless LAN clients and often optionally to WAN clients. This utility may also be an application that is run on a computer, as is the case with as Apple's AirPort, which is managed with the AirPort Utility on
macOS macOS (; previously Mac OS X and later OS X) is a Proprietary software, proprietary graphical user interface, graphical operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for ...
and iOS.


Bridge

Wireless network bridges can act to connect two networks to form a single network at the data-link layer over Wi-Fi. The main standard is the
wireless distribution system A wireless distribution system (WDS) is a system enabling the wireless interconnection of access points in an IEEE 802.11 network. It allows a wireless network to be expanded using multiple access points without the traditional requirement for a ...
(WDS). Wireless bridging can connect a wired network to a wireless network. A bridge differs from an access point: an access point typically connects wireless devices to one wired network. Two wireless bridge devices may be used to connect two wired networks over a wireless link, useful in situations where a wired connection may be unavailable, such as between two separate homes or for devices that have no wireless networking capability (but have wired networking capability), such as consumer entertainment devices; alternatively, a wireless bridge can be used to enable a device that supports a wired connection to operate at a wireless networking standard that is faster than supported by the wireless network connectivity feature (external dongle or inbuilt) supported by the device (e.g., enabling Wireless-N speeds (up to the maximum supported speed on the wired Ethernet port on both the bridge and connected devices including the wireless access point) for a device that only supports Wireless-G). A dual-band wireless bridge can also be used to enable 5 GHz wireless network operation on a device that only supports 2.4 GHz wireless and has a wired Ethernet port.


Repeater

Wireless range-extenders or wireless repeaters can extend the range of an existing wireless network. Strategically placed range-extenders can elongate a signal area or allow for the signal area to reach around barriers such as those pertaining in L-shaped corridors. Wireless devices connected through repeaters suffer from an increased latency for each hop, and there may be a reduction in the maximum available data throughput. Besides, the effect of additional users using a network employing wireless range-extenders is to consume the available bandwidth faster than would be the case whereby a single user migrates around a network employing extenders. For this reason, wireless range-extenders work best in networks supporting low traffic throughput requirements, such as for cases whereby a single user with a Wi-Fi-equipped tablet migrates around the combined extended and non-extended portions of the total connected network. Also, a wireless device connected to any of the repeaters in the chain has data throughput limited by the "weakest link" in the chain between the connection origin and connection end. Networks using wireless extenders are more prone to degradation from interference from neighbouring access points that border portions of the extended network and that happen to occupy the same channel as the extended network.


Embedded systems

The security standard, Wi-Fi Protected Setup, allows embedded devices with a limited graphical user interface to connect to the Internet with ease. Wi-Fi Protected Setup has 2 configurations: The Push Button configuration and the PIN configuration. These embedded devices are also called The
Internet of Things The Internet of things (IoT) describes the network of physical objects—"things" or objects—that are embedded with sensors, software, and other technologies for the purpose of connecting and exchanging data with other devices and systems over ...

Internet of Things
and are low-power, battery-operated embedded systems. Several Wi-Fi manufacturers design chips and modules for embedded Wi-Fi, such as GainSpan. Increasingly in the last few years (particularly ), embedded Wi-Fi modules have become available that incorporate a real-time operating system and provide a simple means of wirelessly enabling any device that can communicate via a serial port. This allows the design of simple monitoring devices. An example is a portable ECG device monitoring a patient at home. This Wi-Fi-enabled device can communicate via the Internet. These Wi-Fi modules are designed by
OEM An original equipment manufacturer (OEM) is generally perceived as a company that produces parts and equipment that may be marketed by another manufacturer. However, the term is also used in several other ways, which causes ambiguity Ambig ...

OEM
s so that implementers need only minimal Wi-Fi knowledge to provide Wi-Fi connectivity for their products. In June 2014,
Texas Instruments Texas Instruments Incorporated (TI) is an n technology company headquartered in , , that designs and manufactures s and various s, which it sells to electronics designers and s globally. It is one of the top 10 semiconductor companies worldwid ...
introduced the first ARM Cortex-M4 microcontroller with an onboard dedicated Wi-Fi MCU, the SimpleLink CC3200. It makes embedded systems with Wi-Fi connectivity possible to build as single-chip devices, which reduces their cost and minimum size, making it more practical to build wireless-networked controllers into inexpensive ordinary objects.


Network security

The main issue with wireless
network security Network security consists of the policies, processes and practices adopted to prevent, detect and monitor unauthorized access, misuse, modification, or denial of a computer network A computer network is a group of computers that use a set ...
is its simplified access to the network compared to traditional wired networks such as Ethernet. With wired networking, one must either gain access to a building (physically connecting into the internal network), or break through an external
firewall Firewall may refer to: * Firewall (computing) In computing, a firewall is a network security system that Network monitoring, monitors and controls incoming and outgoing network traffic based on predetermined security rules. A firewall typically e ...

firewall
. To access Wi-Fi, one must merely be within the range of the Wi-Fi network. Most business networks protect sensitive data and systems by attempting to disallow external access. Enabling wireless connectivity reduces security if the network uses inadequate or no encryption. An attacker who has gained access to a Wi-Fi network router can initiate a DNS spoofing attack against any other user of the network by forging a response before the queried DNS server has a chance to reply.


Securing methods

A common measure to deter unauthorized users involves hiding the access point's name by disabling the SSID broadcast. While effective against the casual user, it is ineffective as a security method because the SSID is broadcast in the clear in response to a client SSID query. Another method is to only allow computers with known MAC addresses to join the network, but determined eavesdroppers may be able to join the network by spoofing an authorized address.
Wired Equivalent Privacy Wired Equivalent Privacy (WEP) is a security algorithm of an algorithm (Euclid's algorithm) for calculating the greatest common divisor (g.c.d.) of two numbers ''a'' and ''b'' in locations named A and B. The algorithm proceeds by successive subtr ...
(WEP) encryption was designed to protect against casual snooping but it is no longer considered secure. Tools such as AirSnort or
Aircrack-ng Aircrack-ng is a network software suite consisting of a detector, packet sniffer, WEP and WPA/ WPA2-PSK cracker and analysis tool for 802.11 wireless LAN A wireless LAN (WLAN) is a wireless computer network that links two or more device ...

Aircrack-ng
can quickly recover WEP encryption keys. Because of WEP's weakness the Wi-Fi Alliance approved Wi-Fi Protected Access (WPA) which uses TKIP. WPA was specifically designed to work with older equipment usually through a firmware upgrade. Though more secure than WEP, WPA has known vulnerabilities. The more secure
WPA2 Wi-Fi Protected Access (WPA), Wi-Fi Protected Access II (WPA2), and Wi-Fi Protected Access 3 (WPA3) are the three security and security certification programs developed by the Wi-Fi Alliance The Wi-Fi Alliance owns the ''Wi-Fi'' trademark ...
using
Advanced Encryption Standard The Advanced Encryption Standard (AES), also known by its original name Rijndael (), is a specification for the encryption In cryptography Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', ...
was introduced in 2004 and is supported by most new Wi-Fi devices. WPA2 is fully compatible with WPA. In 2017, a flaw in the WPA2 protocol was discovered, allowing a key replay attack, known as KRACK. A flaw in a feature added to Wi-Fi in 2007, called Wi-Fi Protected Setup (WPS), let WPA and WPA2 security be bypassed, and effectively broken in many situations. The only remedy as of late 2011 was to turn off Wi-Fi Protected Setup, which is not always possible.
Virtual Private Network A virtual private network (VPN) extends a private network In IP network The Internet protocol suite is the Conceptual model (computer science), conceptual model and set of communications protocols used in the Internet and similar comput ...
s can be used to improve the confidentiality of data carried through Wi-Fi networks, especially public Wi-Fi networks. A
URI A Uniform Resource Identifier (URI) is a unique sequence of characters that identifies a logical or physical resource used by web technologies. URIs may be used to identify anything, including real-world objects, such as people and places, concep ...
using the WIFI scheme can specify the SSID, encryption type, password/passphrase, and if the SSID is hidden or not, so users can follow links from
QR code A QR code (an initialism for Quick Response code) is a type of Barcode#Matrix (2D) barcodes, matrix barcode (or two-dimensional barcode) invented in 1994 by the Japan, Japanese automotive company Denso#Denso Wave, Denso Wave. A barcode is a machi ...

QR code
s, for instance, to join networks without having to manually enter the data. A MECARD-like format is supported by Android and iOS 11+. * Common format: WIFI:S:;T:;P:;H:; * Sample WIFI:S:MySSID;T:WPA;P:MyPassW0rd;;


Data security risks

The older wireless
encryption In cryptography Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in ...

encryption
-standard, Wired Equivalent Privacy (WEP), has been shown easily breakable even when correctly configured. Wi-Fi Protected Access (WPA and WPA2) encryption, which became available in devices in 2003, aimed to solve this problem. Wi-Fi access points typically default to an encryption-free (''open'') mode. Novice users benefit from a zero-configuration device that works out-of-the-box, but this default does not enable any
wireless security Wireless security is the prevention of unauthorized access or damage to computers or data using wireless Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points that do not u ...
, providing open wireless access to a LAN. To turn security on requires the user to configure the device, usually via a software
graphical user interface The graphical user interface (GUI "UI" by itself is still usually pronounced . or ) is a form of user interface In the industrial design Industrial design is a process of design A design is a plan or specification for the construction ...
(GUI). On unencrypted Wi-Fi networks connecting devices can monitor and record data (including personal information). Such networks can only be secured by using other means of protection, such as a
VPN A virtual private network (VPN) extends a private network across a public network and enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network. The ben ...
or secure
Hypertext Transfer Protocol The Hypertext Transfer Protocol (HTTP) is an application layer An application layer is an abstraction layer that specifies the shared communications protocols and Interface (computing), interface methods used by Host (network), hosts in a c ...
over
Transport Layer Security Transport Layer Security (TLS), the successor of the now-deprecated Secure Sockets Layer Transport Layer Security (TLS), the successor of the now-deprecated Secure Sockets Layer Transport Layer Security (TLS), and its now-deprecated predecess ...
(
HTTPS Hypertext Transfer Protocol Secure (HTTPS) is an extension of the Hypertext Transfer Protocol The Hypertext Transfer Protocol (HTTP) is an application layer An application layer is an abstraction layer that specifies the shared commu ...
). Wi-Fi Protected Access encryption (WPA2) is considered secure, provided a strong
passphrase A passphrase is a sequence of words or other text used to control access to a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform g ...
is used. In 2018,
WPA3 Wi-Fi Protected Access (WPA), Wi-Fi Protected Access II (WPA2), and Wi-Fi Protected Access 3 (WPA3) are the three security and security certification programs developed by the Wi-Fi Alliance The Wi-Fi Alliance owns the ''Wi-Fi'' trademark ...
was announced as a replacement for WPA2, increasing security; it rolled out on June 26.


Piggybacking

Piggybacking refers to access to a wireless Internet connection by bringing one's computer within the range of another's wireless connection, and using that service without the subscriber's explicit permission or knowledge. During the early popular adoption of
802.11 IEEE 802.11 is part of the IEEE 802 set of local area network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office buildi ...
, providing open access points for anyone within range to use was encouraged to cultivate
wireless community network Wireless community networks (WCNs) or wireless community projects are organizations that take a grassroots A grassroots movement is one that uses the people in a given district, region, or community as the basis for a political or economic movem ...
s, particularly since people on average use only a fraction of their downstream bandwidth at any given time. Recreational logging and mapping of other people's access points have become known as
wardriving Wardriving is the act of searching for Wi-Fi wireless networks, usually from a moving vehicle, using a laptop or smartphone. Software for wardriving is freely available on the internet. Warbiking, warcycling, warwalking and similar use the same ...
. Indeed, many access points are intentionally installed without security turned on so that they can be used as a free service. Providing access to one's Internet connection in this fashion may breach the Terms of Service or contract with the
ISP#REDIRECT Internet service provider#REDIRECT Internet service provider {{Redirect category shell, 1= {{R from other capitalisation ...
{{Redirect category shell, 1= {{R from other capitalisation ...
. These activities do not result in sanctions in most jurisdictions; however, legislation and
case law Case law is the collection of past legal decisions written by courts and similar tribunal A tribunal, generally, is any person or institution with authority to judge, adjudicate on, or determine claims or disputes—whether or not it is calle ...
differ considerably across the world. A proposal to leave
graffiti Graffiti (both singular and plural; the singular ''graffito'' is rarely used except in archeology) is a type of art genre that means writing or drawings made on a wall or other surface, usually without permission and within public view. Graf ...

graffiti
describing available services was called
warchalking Warchalking is the drawing of symbols in public places to advertise an open Wi-Fi wireless network, network. Inspired by Hobo#Hobo signs (symbols), hobo symbols, the warchalking marks were conceived by a group of friends in June 2002 and publicise ...

warchalking
. Piggybacking often occurs unintentionally – a technically unfamiliar user might not change the default "unsecured" settings to their access point and operating systems can be configured to connect automatically to any available wireless network. A user who happens to start up a laptop in the vicinity of an access point may find the computer has joined the network without any visible indication. Moreover, a user intending to join one network may instead end up on another one if the latter has a stronger signal. In combination with automatic discovery of other network resources (see
DHCP The Dynamic Host Configuration Protocol (DHCP) is a network management protocol used on Internet Protocol The Internet Protocol (IP) is the network layer communications protocol A communication protocol is a system of rules that allows two ...
and
Zeroconf Zero-configuration networking (zeroconf) is a set of technologies that automatically creates a usable computer network A computer network is a group of computers that use a set of common communication protocols over digital signal, digital i ...
) this could lead wireless users to send sensitive data to the wrong middle-man when seeking a destination (see
man-in-the-middle attack In cryptography Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia ''-logy'' is a suffix In linguistics Linguistics is the science, scientific study of lan ...
). For example, a user could inadvertently use an unsecured network to log into a
website A website (also written as web site) is a collection of web page A web page (or webpage) is a hypertext File:Douglas Engelbart in 2008.jpg, Douglas Engelbart in 2009, at the 40th anniversary celebrations of "The Mother of All Demos" i ...

website
, thereby making the login credentials available to anyone listening, if the website uses an insecure protocol such as plain
HTTP The Hypertext Transfer Protocol (HTTP) is an application layer An application layer is an abstraction layer that specifies the shared communications protocols and Interface (computing), interface methods used by Host (network), hosts in a c ...
without TLS. On an unsecured access point, an unauthorized user can obtain security information (factory preset passphrase and/or Wi-Fi Protected Setup PIN) from a label on a wireless access point and use this information (or connect by the Wi-Fi Protected Setup pushbutton method) to commit unauthorized and/or unlawful activities.


Societal aspects

Wireless internet access has become much more embedded in society. It has thus changed how the society functions in many ways.


Influence on developing countries

Over half the world does not have access to the internet, prominently rural areas in developing nations. Technology that has been implemented in more developed nations is often costly and low energy efficient. This has led to developing nations using more low-tech networks, frequently implementing renewable power sources that can solely be maintained through
solar power Solar power is the conversion of renewable energy Renewable energy is energy that is collected from renewable resource File:Global Vegetation.jpg, Global vegetation A renewable resource, also known as a flow resource, is a natural re ...

solar power
, creating a network that is resistant to disruptions such as power outages. For instance, in 2007 a 450 km (280 mile) network between Cabo Pantoja and
Iquitos Iquitos (; ) is the capital city of Peru's Maynas Province, Peru, Maynas Province and Loreto Region. The largest metropolis in the Peruvian Amazon, east of the Andes, it is the List of cities in Peru, ninth-most populous city of Peru. It is th ...

Iquitos
in
Peru , , image_flag = Flag_of_Peru.svg , image_coat = Escudo_nacional_del_Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto ...

Peru
was erected in which all equipment is powered only by
solar panel A solar cell panel, solar electric panel, photo-voltaic (PV) module or just solar panel is an assembly of photo-voltaic cells mounted in a framework for installation. Solar panels use sunlight as a source of energy to generate direct current e ...

solar panel
s. These long-range Wi-Fi networks have two main uses: offer internet access to populations in isolated villages, and to provide healthcare to isolated communities. In the case of the aforementioned example, it connects the central hospital in Iquitos to 15 medical outposts which are intended for remote diagnosis.


Work habits

Access to Wi-Fi in public spaces such as cafes or parks allows people, in particular freelancers, to work remotely. While the accessibility of Wi-Fi is the strongest factor when choosing a place to work (75% of people would choose a place that provides Wi-Fi over one that does not), other factors influence the choice of specific hotspots. These vary from the accessibility of other resources, like books, the location of the workplace, and the social aspect of meeting other people in the same place. Moreover, the increase of people working from public places results in more customers for local businesses thus providing an economic stimulus to the area. Additionally, in the same study it has been noted that wireless connection provides more freedom of movement while working. Both when working at home or from the office it allows the displacement between different rooms or areas. In some offices (notably Cisco offices in New York) the employees do not have assigned desks but can work from any office connecting their laptop to Wi-Fi hotspot.


Housing

The internet has become an integral part of living. 81.9% of American households have internet access. Additionally, 89% of American households with broadband connect via wireless technologies. 72.9% of American households have Wi-Fi. Wi-Fi networks have also affected how the interior of homes and hotels are arranged. For instance, architects have described that their clients no longer wanted only one room as their home office, but would like to work near the fireplace or have the possibility to work in different rooms. This contradicts architect's pre-existing ideas of the use of rooms that they designed. Additionally, some hotels have noted that guests prefer to stay in certain rooms since they receive a stronger Wi-Fi network.


Health concerns

The
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations United Nations Specialized Agencies are autonomous organizations working with the United Nations and each other through the co-ordinating machinery of the Unit ...
(WHO) says, "no health effects are expected from exposure to RF fields from base stations and wireless networks", but notes that they promote research into effects from other RF sources. (a category used when "a causal association is considered credible, but when chance, bias or confounding cannot be ruled out with reasonable confidence"), this classification was based on risks associated with wireless phone use rather than Wi-Fi networks. The United Kingdom's
Health Protection Agency The Health Protection Agency (HPA) was a non-departmental public bodyIn the United Kingdom, non-departmental public body (NDPB) is a classification applied by the Cabinet Office, HM Treasury, Treasury, the Scottish Government and the Northern Irel ...
reported in 2007 that exposure to Wi-Fi for a year results in the "same amount of radiation from a 20-minute mobile phone call". A review of studies involving 725 people who claimed
electromagnetic hypersensitivity Electromagnetic hypersensitivity (EHS) is a claimed sensitivity to electromagnetic fields An electromagnetic field (also EM field) is a classical (i.e. non-quantum) field produced by accelerating electric charge Electric charge is the ph ...
, "...suggests that 'electromagnetic hypersensitivity' is unrelated to the presence of an EMF, although more research into this phenomenon is required."


Alternatives

Several other wireless technologies provide alternatives to Wi-Fi for different use cases: *
Bluetooth Bluetooth is a short-range wireless Wireless communication (or just wireless, when the context allows) is the telecommunication, transfer of information between two or more points that do not use an electrical conductor as a medium by which ...

Bluetooth
, a short-distance network * Bluetooth Low Energy, a low-power variant of Bluetooth *
Zigbee Zigbee is an IEEE 802.15.4-based specification A specification often refers to a set of documented requirements to be satisfied by a material, design, product, or service. A specification is often a type of technical standard A technical sta ...
, a low-power, low data rate, short-distance communication protocol *
Cellular network A cellular network or mobile network is a communication network A telecommunications network is a group of nodes In general, a node is a localized swelling (a "knot") or a point of intersection (a Vertex (graph theory), vertex). Node may re ...
s, used by smartphones *
WiMax Worldwide Interoperability for Microwave Access (WiMAX) is a family of communication standards based on the set of standards, which provide physical layer (PHY) and (MAC) options. The WiMAX Forum was formed in June 2001 to promote conformit ...

WiMax
, for providing long range wireless internet connectivity *
LoRa Lora is a female given name and family name In some cultures, a surname, family name, or last name is the portion of one's personal name 300px, First/given, middle and last/family/surname with John Fitzgerald Kennedy as example. This sho ...
, for long range wireless with low data rate Some alternatives are "no new wires", re-using existing cable: *
G.hn G.hn is a specification for home networking A home network or home area network (HAN) is a type of computer network that facilitates communication among devices within the close vicinity of a home. Devices capable of participating in this ...
, which uses existing home wiring, such as phone and power lines Several ''wired'' technologies for computer networking, which provide viable alternatives to Wi-Fi: *
Ethernet over twisted pair Ethernet over twisted-pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network. They are a subset of all Ethernet physical layers. Early Ethernet used various grades of coaxial cable, but in 1984, StarLA ...


See also

* Gi-Fi—a term used by some trade press to refer to faster versions of the IEEE 802.11 standards * HiperLAN *
Indoor positioning system An indoor positioning system (IPS) is a network of devices used to locate people or objects where GPS and other satellite technologies lack precision or fail entirely, such as inside multistory buildings, airports, alleys, parking garages, and und ...
*
Li-Fi Li-Fi (also written as LiFi) is a technology which utilizes light to transmit data and position between devices. The term was first introduced by during a 2011 talk in . In technical terms, Li-Fi is a light communication system that is capabl ...

Li-Fi
*
List of WLAN channels WLAN A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network A local area network (LAN) is a computer network that interconnects computers within a ...
* Operating system Wi-Fi support *
Power-line communication Power-line communication (also known as power-line carrier or PLC) carries data on a conductor that is also used simultaneously for AC electric power transmission Electric power transmission is the bulk movement of electrical energy from a power ...
* San Francisco Digital Inclusion Strategy *
WiGig WiGig, alternatively known as 60 GHz Wi-Fi, refers to a set of V band, 60 GHz wireless network protocols. It includes the current IEEE 802.11ad standard and also the upcoming IEEE 802.11ay standard. The WiGig specification allows devices to c ...
*
Wireless Broadband Alliance The Wireless Broadband Alliance (WBA) is an industry association formed to promote services interoperability between operators in the Wi-Fi industry, with the stated aim of providing an excellent user experience. To achieve this, the WBA promotes i ...
*
Wi-Fi DirectWi-Fi Direct (formerly Wi-Fi Peer-to-Peer) is a Wi-Fi Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area network A local area network (LAN) is a comput ...

Wi-Fi Direct
*
Hotspot (Wi-Fi) A hotspot is a physical location where people may obtain Internet access Internet access is the ability of individuals and organizations to connect to the using s, s, and other devices; and to access services such as and the . Internet ...
*
Bluetooth Bluetooth is a short-range wireless Wireless communication (or just wireless, when the context allows) is the telecommunication, transfer of information between two or more points that do not use an electrical conductor as a medium by which ...

Bluetooth


References


Notes


Further reading

* {{Telecommunications Australian inventions Computer-related introductions in 1999 Networking standards Wireless communication systems