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{{Short description|Family of wireless network protocols}}
{{distinguish|Hi-Fi|Lo-fi (disambiguation)|Li-Fi}}
{{pp-vandalism|small=yes}}
{{Use Oxford spelling|date=August 2022}}
{{Use dmy dates|date=March 2023}}
{{Infobox protocol
| image = WiFi Logo.svg
| image-upright = 0.5
| alt = A round black-and-white yin-yang logo stating 'Wi-Fi Alliance'
| developer =
| introdate = {{Start date and age|1997|9|21|df=yes}}
| industry =
| connector =
| hardware = [[Personal computer]]s, [[gaming consoles]], [[smart device]]s, [[television]]s, [[Printer (computing)|printer]]s, [[security camera]]s
| range =
}}
{{Antennas|systems}}
'''Wi-Fi''' ({{IPAc-en|ˈ|w|aɪ|f|aɪ}})<ref>{{Cite web |url=https://www.theatlantic.com/technology/archive/2014/06/why-fi-or-wiffy-how-americans-pronounce-techs-most-common-terms/373082/ |title='Why-Fi' or 'Wiffy'? How Americans Pronounce Common Tech Terms |last=Garber |first=Megan |date=23 June 2014 |website=[[The Atlantic]] |archive-url=https://web.archive.org/web/20180615190651/https://www.theatlantic.com/technology/archive/2014/06/why-fi-or-wiffy-how-americans-pronounce-techs-most-common-terms/373082/ |archive-date=15 June 2018 |url-status=live }}</ref>{{Efn|According to a founding member of the Wi-Fi Alliance, "Wi-Fi" has no expanded meaning, and was simply chosen as a more memorable name for the technology. Some Wi-Fi Alliance materials produced soon after this selection used the phrase ''wireless fidelity'', but this was quickly dropped.<ref>{{cite web |url=https://www.newscientist.com/question/what-does-wi-fi-stand-for/ |title=What Does Wi-Fi Stand For? |access-date=7 January 2022 |archive-date=5 January 2022 |archive-url=https://web.archive.org/web/20220105184518/https://www.newscientist.com/question/what-does-wi-fi-stand-for/ |url-status=live }}</ref>}} is a family of [[wireless network]] protocols based on the [[IEEE 802.11]] family of standards, which are commonly used for [[Wireless LAN|local area networking]] of devices and [[Internet]] access, allowing nearby digital devices to exchange data by [[radio wave]]s. These are the most widely used computer networks, used globally in [[small office/home office|home and small office networks]] to link devices and to provide [[Internet access]] with [[wireless router]]s and [[wireless access point]]s in public places such as coffee shops, restaurants, hotels, libraries, and airports.
''Wi-Fi'' is a trademark of the [[Wi-Fi Alliance]], which restricts the use of the term "''Wi-Fi Certified''" to products that successfully complete [[Interoperability Solutions for European Public Administrations|interoperability]] certification testing.<ref>{{cite web |url=http://www.webopedia.com/TERM/W/Wi_Fi.html |title=What is Wi-Fi (IEEE 802.11x)? A Webopedia Definition |last=Beal |first=Vangie |website=Webopedia |date=2 May 2001 |archive-url=https://web.archive.org/web/20120308123721/http://www.webopedia.com/term/w/wi_fi.html |archive-date=8 March 2012 |url-status=live }}</ref><ref>{{Cite news|url=https://www.theguardian.com/technology/blog/2007/may/21/thedangersof |title=The Dangers of Wi-Fi Radiation (Updated) |first=Jack |last=Schofield |newspaper=The Guardian |date=21 May 2007 |via=TheGuardian.com |access-date=1 November 2019 |archive-date=1 November 2019 |archive-url=https://web.archive.org/web/20191101204649/https://www.theguardian.com/technology/blog/2007/may/21/thedangersof |url-status=live }}</ref><ref>{{Cite web |url=https://www.wi-fi.org/certification |title=Certification |publisher=Wi-Fi Alliance |website=Wi-Fi.org |access-date=1 November 2019 |archive-date=13 May 2020 |archive-url=https://web.archive.org/web/20200513210825/https://wi-fi.org/certification |url-status=live }}</ref> Non-compliant hardware is simply referred to as [[WLAN]], and it may or may not work with "''Wi-Fi Certified''" devices. {{As of|2017|post=,}} the Wi-Fi Alliance consisted of more than 800 companies from around the world.<ref name="alliance-history">{{Cite web |title=History | Wi-Fi Alliance |url=https://www.wi-fi.org/who-we-are/history |access-date=15 September 2020 |website=Wi-Fi Alliance |archive-date=24 October 2017 |archive-url=https://web.archive.org/web/20171024205733/https://www.wi-fi.org/who-we-are/history |url-status=live }}</ref> {{As of|2019|post=,}} over 3.05 billion Wi-Fi-enabled devices are shipped globally each year.<ref name="global-forecast" />
Wi-Fi uses multiple parts of the [[IEEE 802]] [[Communication protocol|protocol]] family and is designed to work well with its wired sibling, [[Ethernet]]. Compatible devices can network through [[wireless access point]]s with each other as well as with wired devices and the Internet. Different versions of Wi-Fi are specified by various [[IEEE 802.11]] protocol standards, with different radio technologies determining radio bands, maximum ranges, and speeds that may be achieved. Wi-Fi most commonly uses the {{convert|2.4|GHz|mm}} [[UHF]] and {{convert|5|GHz|mm|sigfig=1}} [[Super high frequency|SHF]] radio bands, with the 6 gigahertz SHF band used in newer generations of the standard; these bands are subdivided into multiple channels. Channels can be shared between networks, but, within range, only one transmitter can transmit on a channel at a time.
[[File:TP-Link_AX1500_Wi-Fi_6_Router_Front.jpg|thumb|TP-Link AX1500 Wi-Fi 6 Router]]
Wi-Fi's radio bands work best for [[line-of-sight propagation|line-of-sight]] use. Common obstructions, such as walls, pillars, home appliances, etc., may greatly reduce range, but this also helps minimize interference between different networks in crowded environments. The range of an access point is about {{convert|20|m|ft|abbr=on|sp=us}} indoors, while some access points claim up to a {{convert|150|m|abbr=on|sp=us}} range outdoors. Hotspot coverage can be as small as a single room with walls that block radio waves or as large as many square kilometers using multiple overlapping access points with [[roaming]] permitted between them. Over time, the speed and [[spectral efficiency]] of Wi-Fi has increased. {{As of|2019|post=,}} some versions of Wi-Fi, running on suitable hardware at close range, can achieve speeds of 9.6 Gbit/s ([[gigabit]] per second).<ref>{{cite web |url=https://www.theverge.com/2019/2/21/18232026/wi-fi-6-speed-explained-router-wifi-how-does-work |title=Wi-Fi 6: is it really that much faster? |date=21 February 2019 |access-date=18 September 2022 |archive-date=20 September 2022 |archive-url=https://web.archive.org/web/20220920171504/https://www.theverge.com/2019/2/21/18232026/wi-fi-6-speed-explained-router-wifi-how-does-work |url-status=live }}</ref>
== History ==
{{main|IEEE 802.11#History}}
A 1985 ruling by the U.S. Federal Communications Commission released parts of the [[ISM band]]s for unlicensed use for communications.<ref>{{cite web|url=http://www.marcus-spectrum.com/documents/81413RO.txt |format=txt |title=Authorization of Spread Spectrum Systems Under Parts 15 and 90 of the FCC Rules and Regulations |publisher=Federal Communications Commission of the USA |date=18 June 1985 |access-date=31 August 2007 |url-status=dead |archive-url=https://web.archive.org/web/20070928054826/http://www.marcus-spectrum.com/documents/81413RO.txt |archive-date=28 September 2007 }}</ref> These frequency bands include the same 2.4 GHz bands used by equipment such as [[microwave oven]]s, and are thus subject to interference.<ref name="scienceabc" />
In 1991 in [[Nieuwegein]], the [[NCR Corporation]] and [[AT&T Corporation|AT&T]] invented the precursor to 802.11,<ref name="birth" /> intended for use in cashier systems, under the name [[WaveLAN]]. NCR's [[Vic Hayes]], who held the chair of IEEE 802.11 for ten years, along with [[Bell Labs]] engineer Bruce Tuch, approached the [[Institute of Electrical and Electronics Engineers]] (IEEE) to create a standard and were involved in designing the initial 802.11b and 802.11a specifications within the IEEE.<ref>{{cite web |url=http://news.cnet.com/1200-1070-975460.html |title=Vic Hayes – Wireless Vision |author=Ben Charny |date=6 December 2002 |website=[[CNET]] |access-date=30 April 2011 |url-status=dead |archive-url=https://web.archive.org/web/20120826164642/http://news.cnet.com/1200-1070-975460.html |archive-date=26 August 2012 }}</ref> They have both been subsequently inducted into the Wi-Fi NOW Hall of Fame.<ref>{{cite news|title=Vic Hayes & Bruce Tuch inducted into the Wi-Fi Now Hall of Fame|url=https://wifinowglobal.com/news-and-blog/vic-hayes-bruce-tuch-inducted-into-the-wi-fi-now-hall-of-fame/|newspaper=Wi-Fi Now Global|date=8 November 2019|access-date=27 November 2020|archive-date=7 December 2020|archive-url=https://web.archive.org/web/20201207194505/https://wifinowglobal.com/news-and-blog/vic-hayes-bruce-tuch-inducted-into-the-wi-fi-now-hall-of-fame/|url-status=live|last1=Hetting |first1=Claus }}</ref>
In 1989 in Australia, a team of scientists began working on wireless LAN technology.<ref>{{Cite journal |last=Rimmer |first=Matthew |date=27 April 2007 |title=CSIRO wins Wi-Fi patent litigation |url=https://eprints.qut.edu.au/215127/1/132231.pdf |journal=Australian Intellectual Property Newsletter Archive |via=QUT}}</ref> A prototype [[test bed]] for a [[wireless local area network]] (WLAN) was developed in 1992 by a team of researchers from the Radiophysics Division of the [[CSIRO]] (Commonwealth Scientific and Industrial Research Organisation) in Australia, led by [[John O'Sullivan (engineer)|John O'Sullivan]].<ref name="csirowifi" /> A patent for Wi Fi was lodged by the CSIRO in 1992.<ref name="O’Sullivan 147–147">{{Cite journal |last=O’Sullivan |first=John |date=February 2018 |title=How we made the wireless network |url=https://www.nature.com/articles/s41928-018-0027-y |journal=Nature Electronics |language=en |volume=1 |issue=2 |pages=147 |doi=10.1038/s41928-018-0027-y |s2cid=257090965 |issn=2520-1131|url-access=subscription }}</ref>
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]] to permit 11 Mbit/s link speeds.
In 1999, the [[Wi-Fi Alliance]] formed as a trade association to hold the Wi-Fi trademark under which most IEEE 802.11 products are sold.<ref>{{cite web |title= Wi-Fi Alliance: Organization |publisher= Official industry association Web site |url= http://www.wi-fi.org/organization.php |access-date= 23 August 2011 |url-status=live |archive-url= https://web.archive.org/web/20090903004711/http://www.wi-fi.org/organization.php |archive-date= 3 September 2009 }}</ref>
[[File:Apple Airport Extreme 802.11g card.jpg|thumb|Apple Airport Extreme installed in an iBook G4]]
The major commercial breakthrough came with [[Apple Inc.]] adopting Wi-Fi for their [[iBook]] series of laptops in 1999.<ref name="birth"/> It was the first mass consumer product to offer Wi-Fi network connectivity, which was then branded by Apple as [[AirPort]].<ref>{{cite news|access-date=2 January 2023|date=12 July 2004|language=en|quote=in July 1999 Apple introduced Wi-Fi as an option on its new iBook computers, under the brand name AirPort|title=A brief history of Wi-Fi|url=https://www.economist.com/technology-quarterly/2004/06/12/a-brief-history-of-wi-fi|newspaper=[[The Economist]]|archive-date=2 January 2023|archive-url=https://web.archive.org/web/20230102075107/https://www.economist.com/technology-quarterly/2004/06/12/a-brief-history-of-wi-fi|url-status=live}}<!-- auto-translated by Module:CS1 translator --></ref> 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]].<ref>{{cite news|url=https://www.nytimes.com/1999/07/22/business/apple-offers-imac-s-laptop-offspring-the-ibook.html|title=Apple Offers iMac's Laptop Offspring, the iBook|author=Steve Lohr|newspaper=[[The New York Times]]|date=22 July 1999|access-date=28 November 2020|archive-date=2 February 2017|archive-url=https://web.archive.org/web/20170202003816/http://www.nytimes.com/1999/07/22/business/apple-offers-imac-s-laptop-offspring-the-ibook.html|url-status=live}}</ref><ref>{{cite web|url=https://www.nytimes.com/1999/11/25/technology/state-of-the-art-not-born-to-be-wired.html?pagewanted=all|title=State of the Art; Not Born To Be Wired|first=Peter H.|last=Lewis|newspaper=The New York Times|date=25 November 1999|access-date=28 November 2020|archive-date=2 February 2017|archive-url=https://web.archive.org/web/20170202002735/http://www.nytimes.com/1999/11/25/technology/state-of-the-art-not-born-to-be-wired.html?pagewanted=all|url-status=live}}</ref>
In 2000, Radiata, a group of Australian scientists connected to the CSIRO, were the first to use the 802.11a standard on chips connected to a Wi-Fi network.<ref name="O’Sullivan 147–147"/>
Wi-Fi uses a large number of [[patent]]s held by multiple different organizations.<ref>{{Cite web|url=https://standards.ieee.org/about/sasb/patcom/patents/|archive-url=https://web.archive.org/web/20120410074816/http://standards.ieee.org/about/sasb/patcom/pat802_11.html|url-status=live|title=IEEE SA – Records of IEEE Standards-Related Patent Letters of Assurance|archive-date=10 April 2012|website=[[IEEE]]}}</ref> Australia,<ref>{{cite web|url=http://www.australiangeographic.com.au/journal/world-changing-aussie-inventions.htm|title=World changing Aussie inventions|work=[[Australian Geographic]]| archive-url=https://web.archive.org/web/20111215082408/http://www.australiangeographic.com.au/journal/world-changing-aussie-inventions.htm|archive-date=15 December 2011|url-status=dead}}</ref> the United States<ref>{{cite web |last1=Field |first1=Shivaune |title=Hedy Lamarr: The Incredible Mind Behind Secure WiFi, GPS And Bluetooth |url=https://www.forbes.com/sites/shivaunefield/2018/02/28/hedy-lamarr-the-incredible-mind-behind-secure-wi-fi-gps-bluetooth/?sh=5871237541b7 |work=forbes.com |archive-url=https://web.archive.org/web/20230419123256/https://www.forbes.com/sites/shivaunefield/2018/02/28/hedy-lamarr-the-incredible-mind-behind-secure-wi-fi-gps-bluetooth/?sh=5871237541b7 |access-date=19 April 2023|archive-date=19 April 2023 }}</ref> and the Netherlands<ref>{{cite web |last1=Van Der Meer |first1=Hilde |title=10 Inventions You Didn't Know Were Dutch |url=https://investinholland.com/news/10-inventions-didnt-know-dutch/ |website=investinholland.com |date=26 March 2018 |publisher=Netherlands Foreign Investment Agency |archive-url=https://web.archive.org/web/20230419124142/https://investinholland.com/news/10-inventions-didnt-know-dutch/ |access-date=19 April 2023|archive-date=19 April 2023 }}</ref> simultaneously claim the invention of Wi-Fi, and a consensus has not been reached globally.<ref>{{cite web|url=https://arstechnica.com/tech-policy/news/2012/04/how-the-aussie-government-invented-wifi-and-sued-its-way-to-430-million.ars|title=How the Aussie government "invented WiFi" and sued its way to $430 million|last=Mullin|first=Joe|date=4 April 2012|work=[[Ars Technica]]|archive-url=https://web.archive.org/web/20120508201202/http://arstechnica.com/tech-policy/news/2012/04/how-the-aussie-government-invented-wifi-and-sued-its-way-to-430-million.ars|archive-date=8 May 2012|url-status=live}}</ref><ref name="patent-troll">{{cite news|url=https://www.cbsnews.com/news/australias-biggest-patent-troll-goes-after-at038t-verizon-and-t-mobile/|title=Australia's Biggest Patent Troll Goes After AT&T, Verizon and T-Mobile|last=Popper|first=Ben|date=3 June 2010|work=[[CBS News]]|archive-url=https://web.archive.org/web/20130506135649/http://www.cbsnews.com/8301-505124_162-43340647/australias-biggest-patent-troll-goes-after-at038t-verizon-and-t-mobile/|archive-date=6 May 2013|url-status=live}}</ref> In 2009, the Australian [[CSIRO]] was awarded $200 million after a patent settlement with 14 technology companies, with a further $220 million awarded in 2012 after legal proceedings with 23 companies.<ref>{{cite web |last1=Brodkin |first1=Jon |date=31 March 2012 |title=WiFi patent case results in $229 million payment to Australian government |url=https://arstechnica.com/tech-policy/2012/04/wifi-patent-case-results-in-229m-payment-to-australian-government/ |archive-url=https://web.archive.org/web/20230419131311/https://arstechnica.com/tech-policy/2012/04/wifi-patent-case-results-in-229m-payment-to-australian-government/ |archive-date=19 April 2023 |access-date=19 April 2023 |website=Ars Technica}}</ref><ref>{{cite web|url=https://www.smh.com.au/technology/australian-scientists-cash-in-on-wifi-invention-20120331-1w5gx.html|title=Australian scientists cash in on Wi-Fi invention|last=Schubert|first=Misha|date=31 March 2012|work=[[The Sydney Morning Herald]]|archive-url=https://web.archive.org/web/20120401162238/http://www.smh.com.au/it-pro/government-it/australian-scientists-cash-in-on-wifi-invention-20120331-1w5gx.html|archive-date=1 April 2012|url-status=live}}</ref><ref>{{cite web|url=https://www.abc.net.au/news/2012-04-01/csiro-receives-payment-for-wifi-technology/3925814|title=CSIRO wins legal battle over wi-fi patent|date=1 April 2012|work=[[ABC News (Australia)|ABC News]]|access-date=27 February 2019|archive-date=7 August 2019|archive-url=https://web.archive.org/web/20190807090636/https://www.abc.net.au/news/2012-04-01/csiro-receives-payment-for-wifi-technology/3925814|url-status=live}}</ref>
In 2016, the CSIRO's WLAN prototype test bed was chosen as Australia's contribution to the exhibition ''[[A History of the World in 100 Objects]]'' held in the [[National Museum of Australia]].<ref name="csirowifi" />
== Etymology and terminology ==
The name ''Wi-Fi'', commercially used as early as August 1999,<ref>{{cite web|url=http://tsdr.uspto.gov/documentviewer?caseId=sn75799629&docId=IPC20070420145537#docIndex=19&page=3|title=Statement of Use, s/n 75799629, US Patent and Trademark Office Trademark Status and Document Retrieval|date=23 August 2005|archive-url=https://web.archive.org/web/20150428011752/http://tsdr.uspto.gov/documentviewer?caseId=sn75799629&docId=IPC20070420145537#docIndex=19&page=3|archive-date=28 April 2015|url-status=live|access-date=21 September 2014|quote=first used the Certification Mark … as early as August 1999}}</ref> 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'."<ref name="boing" /><ref name="wifi_debunked" /> According to Phil Belanger, a founding member of the Wi-Fi Alliance, the term ''Wi-Fi'' was chosen from a list of ten names that Interbrand proposed.<ref name="boing" /> Interbrand also created the Wi-Fi [[logo]]. The [[yin-yang]] Wi-Fi logo indicates the certification of a product for [[interoperability]].<ref name="wifi_securing_2003" /> The name is often written as ''WiFi'', ''Wifi'', or ''wifi'', but these are not approved by the Wi-Fi Alliance.
The name ''Wi-Fi'' is ''not'' short-form for 'Wireless Fidelity',<ref>{{Cite news |last=Corrigan |first=Hope |date=2022-12-30 |title=I just found out what Wi-Fi means and it's sending me |url=https://www.pcgamer.com/i-just-found-out-what-wi-fi-means-and-its-sending-me/ |access-date=2025-05-02 |work=PC Gamer |language=en}}</ref> although the Wi-Fi Alliance did use the [[advertising slogan]] "The Standard for Wireless Fidelity" for a short time after the brand name was created,<ref name="boing" /><ref name="wifi_securing_2003">{{cite web | url=http://www.netsense.info/downloads/Whitepaper_Wi-Fi_Networks2-6-03.pdf | title=Securing Wi-Fi Wireless Networks with Today's Technologies | date=6 February 2003 | publisher=Wi-Fi Alliance | access-date=25 June 2015 | url-status=live | archive-url=https://web.archive.org/web/20150626100202/http://www.netsense.info/downloads/Whitepaper_Wi-Fi_Networks2-6-03.pdf | archive-date=26 June 2015 }}</ref><ref name="wifi_deployment_2004">{{cite web|url=http://www.wi-fi.org/files/wp_6_WPA%20Deployment%20for%20Public%20Access_10-28-04.pdf |title=WPA Deployment Guidelines for Public Access Wi-Fi Networks |date=28 October 2004 |publisher=Wi-Fi Alliance |access-date=30 November 2009 |url-status=dead |archive-url=https://web.archive.org/web/20070306081352/http://www.wi-fi.org/files/wp_6_WPA%20Deployment%20for%20Public%20Access_10-28-04.pdf |archive-date=6 March 2007 }}</ref> and the Wi-Fi Alliance was also called the "Wireless Fidelity Alliance Inc." in some publications.<ref>{{cite book |title=HTC S710 User Manual |date=2006 |publisher=High Tech Computer Corp. |page=2 |quote=Wi-Fi is a registered trademark of the Wireless Fidelity Alliance, Inc.}}</ref> [[IEEE]] is a separate, but related, organization and their website has stated "WiFi is a short name for Wireless Fidelity".<ref>{{cite web|url=https://www.ieee.org/about/technologies/emerging/wifi.pdf|title=Wireless Fidelity{{snd}}WiFi|last=Varma|first=Vijay K.|website=[[Institute of Electrical and Electronics Engineers]] (IEEE) |archive-url=https://web.archive.org/web/20170829232140/http://www.ieee.org/about/technologies/emerging/wifi.pdf|archive-date=29 August 2017|url-status=dead|access-date=16 October 2016}} (originally published 2006)</ref><ref>{{Cite journal|last1=Aime|first1=Marco|last2=Calandriello|first2=Giorgio|last3=Lioy|first3=Antonio|year=2007|title=Dependability in Wireless Networks: Can We Rely on WiFi?|url=http://porto.polito.it/1515418/1/WiFi_dependability_abstract.pdf|journal=IEEE Security & Privacy|volume=5|issue=1|pages=23–29|doi=10.1109/MSP.2007.4|s2cid=16415685 |issn = 1540-7993}}</ref> The name ''Wi-Fi'' was partly chosen because it sounds similar to [[Hi-Fi]], which consumers take to mean ''high fidelity'' or ''high quality''. Interbrand hoped consumers would find the name catchy, and that they would assume this ''wireless'' protocol has high fidelity because of its name.<ref>{{Cite web |date=2019-04-15 |title=You May Feel Silly When You Find Out What Wi-Fi Actually Stands For |url=https://www.huffpost.com/entry/why-called-wi-fi_l_5cace3f7e4b01bf960065841 |access-date=2024-06-19 |website=HuffPost |language=en}}</ref>
Other technologies intended for fixed points, including [[Motorola Canopy]], are usually called ''[[fixed wireless]]''. Alternative wireless technologies include [[Zigbee]], [[Z-Wave]], [[Bluetooth]] and [[mobile phone standards]].
To connect to a Wi-Fi LAN, a computer must be equipped with a [[wireless network interface controller]]. The combination of a computer and an interface controller is called a ''[[Station (networking)|station]]''. Stations are identified by one or more [[MAC address]]es.
Wi-Fi nodes often operate in infrastructure mode in which all communications go through a base station. ''[[Ad hoc mode]]'' refers to devices communicating directly with each other, without communicating with an access point.
A [[Service set (802.11 network)|service set]] is the set of all the devices associated with a particular Wi-Fi network. Devices in a service set need not be on the same wavebands or channels. A service set can be local, independent, extended, mesh, or a combination. Each service set has an associated identifier, a 32-byte service set identifier (SSID), which identifies the network. The [[SSID]] is configured within the devices that are part of the network. A basic service set (BSS) is a group of stations that share the same wireless channel, SSID, and other settings that have wirelessly connected, usually to the same access point.<ref name="IEEE802.11-2007">{{cite web|url=https://standards.ieee.org/getieee802/802.11.html|title=IEEE 802.11-2007: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications|date=8 March 2007|publisher=[[IEEE Standards Association]]|archive-url=https://web.archive.org/web/20070418182559/http://standards.ieee.org/getieee802/802.11.html|archive-date=18 April 2007|url-status=dead}}</ref>{{rp|3.6}} Each BSS is identified by a MAC address called the ''BSSID''.
== Certification ==
[[File:Wifi certified logo.png|thumb|upright=0.5|Wi-Fi certification logo]]
The [[IEEE]] does not test equipment for compliance with their standards. The [[Wi-Fi Alliance]] was formed in 1999 to establish and enforce standards for interoperability and [[backward compatibility]], and to promote [[wireless]] local-area-network technology. The Wi-Fi Alliance enforces the use of the Wi-Fi brand to technologies based on the [[IEEE 802.11]] standards from the IEEE. 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 [[Wi-Fi Protected Access|WPA and WPA2]] security standards, and the [[Extensible Authentication Protocol|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.<ref>{{cite web
|url = http://www.wi-fi.org/certification_programs.php
|title = Wi-Fi Alliance: Programs
|publisher = www.wi-fi.org
|access-date = 22 October 2009
|url-status = live
|archive-url = https://web.archive.org/web/20091125024029/http://www.wi-fi.org/certification_programs.php
|archive-date = 25 November 2009
}}</ref>
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.<ref>{{cite web|title=Wi-Fi Alliance|url=http://whatis.techtarget.com/definition/Wi-Fi-Alliance|publisher=TechTarget|access-date=8 April 2016|url-status=live|archive-url=https://web.archive.org/web/20160422151727/http://whatis.techtarget.com/definition/Wi-Fi-Alliance|archive-date=22 April 2016}}</ref> The Wi-Fi Alliance may or may not sanction derivative terms, such as [[Super Wi-Fi]],<ref>{{cite web|title=Wi-Fi Alliance® statement regarding "Super Wi-Fi"|url=http://www.wi-fi.org/news-events/newsroom/wi-fi-alliance-statement-regarding-super-wi-fi|publisher=Wi-Fi Alliance|access-date=8 April 2016|url-status=live|archive-url=https://web.archive.org/web/20160409001236/http://www.wi-fi.org/news-events/newsroom/wi-fi-alliance-statement-regarding-super-wi-fi|archive-date=9 April 2016}}</ref> coined by the US [[Federal Communications Commission]] (FCC) to describe proposed networking in the UHF TV band in the US.<ref name="Super">{{cite magazine |url=https://www.pcmag.com/article2/0,2817,2399447,00.asp |title='Super Wi-Fi': Super, But Not Wi-Fi |author=Sascha Segan |date=27 January 2012 |magazine=[[PC Magazine]] |access-date=8 April 2016 |url-status=live |archive-url=https://web.archive.org/web/20160420010038/http://www.pcmag.com/article2/0,2817,2399447,00.asp |archive-date=20 April 2016 }}</ref>
==Versions and generations==
{{Wi-Fi generations}}
Equipment frequently supports 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 listed the versions of Wi-Fi supported using the name of the IEEE standards. In 2018, the [[Wi-Fi Alliance]] introduced simplified Wi-Fi generational numbering to indicate equipment that supports Wi-Fi 4 ([[802.11n]]), Wi-Fi 5 ([[802.11ac]]) 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.<ref>{{Cite web |url=https://www.wi-fi.org/news-events/newsroom/wi-fi-alliance-introduces-wi-fi-6 |title=Wi-Fi Alliance Introduces Wi-Fi 6 |publisher=Wi-Fi Alliance |date=3 October 2018 |access-date=24 October 2019 |archive-date=3 April 2019 |archive-url=https://web.archive.org/web/20190403165940/https://www.wi-fi.org/news-events/newsroom/wi-fi-alliance-introduces-wi-fi-6 |url-status=live }}</ref><ref name="generational" />
The most important standards affecting Wi‑Fi are: 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'''),<ref name="generational" /> 802.11ad, 802.11af, 802.11-2016, 802.11ah, 802.11ai, 802.11aj, [[802.11aq]], 802.11ax ('''Wi-Fi 6'''),<ref name="generational" /> [[802.11ay]].
==Uses==
=== Internet ===
[[File:SSID ESS.svg|thumb|An example of a service set called ''WiFi Wikipedia'' consisting of two basic service sets. The clients automatically [[roaming|roam]] between the two BSSs without the user having to explicitly connect to the second network.]]
Wi-Fi technology may be used to provide local network and [[Internet access]] 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 can extend from an area as small as a few rooms to as large as many square kilometres. 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]]s in London. An international example is [[Fon Wireless|Fon]].
Wi-Fi provides services in private homes, businesses, as well as in public spaces. [[Wi-Fi hotspot]]s may be set up either free of charge or commercially, often using a [[captive portal]] webpage for access. Organizations, enthusiasts, authorities and [[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. [[Router (computing)|Routers]] often incorporate a [[digital subscriber line]] modem or a [[cable modem]] and a Wi-Fi access point, are frequently set up in homes and other buildings, to provide Internet access for the structure.
Similarly, battery-powered routers may include a [[mobile broadband modem]] and a Wi-Fi access point. When subscribed to a cellular data carrier, they allow nearby Wi-Fi stations to access the Internet. A number of smartphones have a built-in [[mobile hotspot]] capability of this sort, though carriers often disable the feature, or charge a separate fee to enable it. Standalone devices such as [[MiFi]]- and [[WiBro]]-branded devices provide the capability. Some laptops that have a cellular modem card can also act as mobile Internet Wi-Fi access points.
Multiple traditional university campuses in the developed world provide at least partial Wi-Fi coverage. [[Carnegie Mellon University]] built the first campus-wide wireless Internet network, called [[Wireless Andrew]], at its [[Pittsburgh]] campus in 1993 before Wi-Fi branding existed.<ref>{{cite web|url=http://popcitymedia.com/innovationnews/wifi100511.aspx|title=How Wi-Fi got its start on the campus of CMU, a true story|last=Smit|first=Deb|date=5 October 2011|website=[[Pop City]]|archive-url=https://web.archive.org/web/20111007191316/http://www.popcitymedia.com/innovationnews/wifi100511.aspx|archive-date=7 October 2011|url-status=dead|access-date=6 October 2011}}</ref><ref>{{cite web | title=Wireless Andrew: Creating the World's First Wireless Campus | publisher=Carnegie Mellon University | year=2007 | url=http://www.cmu.edu/corporate/news/2007/features/wireless_andrew.shtml | access-date=6 October 2011 | url-status=dead | archive-url=https://web.archive.org/web/20110901202026/http://www.cmu.edu/corporate/news/2007/features/wireless_andrew.shtml | archive-date=1 September 2011 }}</ref><ref>{{cite book|url=https://books.google.com/books?id=-OMoL5Irm08C&pg=PA121|title=The Innovation Journey of Wi-Fi: The Road to Global Success|last1=Lemstra|first1=Wolter|last2=Hayes|first2=Vic|last3=Groenewegen|first3=John|publisher=Cambridge University Press|year=2010|isbn=978-0-521-19971-1|page=121|author-link2=Vic Hayes|access-date=6 October 2011|archive-url=https://web.archive.org/web/20121112175135/http://books.google.com/books?id=-OMoL5Irm08C&pg=PA121|archive-date=12 November 2012|url-status=live}}</ref> A number of universities collaborate in providing Wi-Fi access to students and staff through the [[Eduroam]] international authentication infrastructure.
=== City-wide ===
{{Further|Municipal wireless network}}
[[File:Metro Wireless Node.jpg|thumb|An outdoor Wi-Fi access point]]
In the early 2000s, multiple cities around the world announced plans to construct citywide Wi-Fi networks. There are a number of successful examples; in 2004, [[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.<ref>{{cite web|url=https://www.telegraphindia.com/opinion/say-hello-to-india-s-first-wirefree-city/cid/1025843|title=Say Hello to India's First Wirefree City|last=Verma|first=Veruna|date=20 August 2006|work=[[The Telegraph (Calcutta)|The Telegraph]]|archive-url=https://web.archive.org/web/20120120071302/http://www.telegraphindia.com/1060820/asp/opinion/story_6632793.asp|archive-date=20 January 2012|url-status=live}}</ref>
In 2005, [[St. Cloud, Florida]] and [[Sunnyvale, California]], became the first cities in the United States to offer citywide free Wi-Fi (from [[MetroFi]]).<ref>{{cite web|url=http://www.besttech.com.tr/urun/bq100-gsm-role-kontrol/|title=Sunnyvale Uses Metro Fi|publisher=besttech.com.tr|language=tr|archive-url=https://web.archive.org/web/20150722113251/http://www.besttech.com.tr/urun/bq100-gsm-role-kontrol/|archive-date=22 July 2015|url-status=dead}}</ref> [[Minneapolis]] has generated $1.2 million in profit annually for [[Minneapolis wireless internet network|its provider]].<ref>{{cite news|url=http://www.startribune.com/business/111286134.html|title=Minneapolis moves ahead with wireless|last1=Alexander|first1=Steve|date=5 December 2010|work=[[The Star Tribune]]|archive-url=https://web.archive.org/web/20101209140054/http://www.startribune.com/business/111286134.html|archive-date=9 December 2010|url-status=dead|last2=Brandt|first2=Steve}}</ref>
In May 2010, the then [[London]] mayor [[Boris Johnson]] pledged to have London-wide Wi-Fi by 2012.<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/uk_news/england/london/8692103.stm|title=London-wide wi-fi by 2012 pledge|date=19 May 2010|work=[[BBC News]]|access-date=19 May 2010|archive-url=https://web.archive.org/web/20100522121915/http://news.bbc.co.uk/2/hi/uk_news/england/london/8692103.stm|archive-date=22 May 2010|url-status=live}}</ref> Several [[London boroughs|boroughs]] including [[City of Westminster|Westminster]] and [[London Borough of Islington|Islington]]<ref>{{cite web|url=http://www.govtech.com/dc/118717|title=City of London Fires Up Europe's Most Advanced Wi-Fi Network|last=Bsu|first=Indrajit|date=14 May 2007|work=Digital Communities|access-date=14 May 2007|archive-url=https://web.archive.org/web/20080907195450/http://www.govtech.com/dc/118717|archive-date=7 September 2008|url-status=dead}}</ref><ref>{{cite web|url=https://www.zdnet.com/home-and-office/networking/london-gets-a-mile-of-free-wi-fi/|title=London gets a mile of free Wi-Fi|last=Wearden|first=Graeme|date=18 April 2005|work=[[ZDNet]]|archive-url=https://web.archive.org/web/20151107174238/http://www.zdnet.com/article/london-gets-a-mile-of-free-wi-fi/|archive-date=7 November 2015|url-status=live|access-date=6 January 2015}}</ref> already had extensive outdoor Wi-Fi coverage at that point.
[[New York City]] announced a city-wide campaign to convert old [[phone booths]] into [[digital kiosk]]s in 2014. The project, titled [[LinkNYC]], has created a network of kiosks that serve as public Wi-Fi hotspots, high-definition screens and [[landline]]s. 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.<ref name="Forbes-PayPhonesWifiKiosks-2014">{{cite web|last=Chowdhry|first=Amit|date=19 November 2014|title=Pay Phones In NYC To Be Replaced With Up To 10,000 Free Wi-Fi Kiosks Next Year|url=https://www.forbes.com/sites/amitchowdhry/2014/11/19/linknyc-free-wifi/#11c29eb27028|access-date=17 September 2016|website=[[Forbes]]|archive-date=22 September 2016|archive-url=https://web.archive.org/web/20160922212101/http://www.forbes.com/sites/amitchowdhry/2014/11/19/linknyc-free-wifi/#11c29eb27028|url-status=live}}</ref><ref name="WNYC-GoodbyePayPhones-20162">{{cite news|last1=Gould|first1=Jessica|date=5 January 2016|title=Goodbye Pay Phones, Hello LinkNYC|work=[[WNYC]]|url=https://www.wnyc.org/story/goodbye-pay-phones-hello-linknyc/|access-date=26 January 2016|archive-date=20 August 2016|archive-url=https://web.archive.org/web/20160820213828/http://www.wnyc.org/story/goodbye-pay-phones-hello-linknyc/|url-status=live}}</ref><ref name="WashingtonPost-PayphoneOfTheFuture-2014">{{cite news|date=17 November 2014|title=New York City unveils the pay phone of the future{{snd}}and it does a whole lot more than make phone calls|newspaper=[[Washington Post]]|url=https://www.washingtonpost.com/news/wonk/wp/2014/11/17/new-york-city-unveils-the-payphone-of-the-future-and-it-does-a-whole-lot-more-than-make-phone-calls/|access-date=17 September 2016|archive-date=19 September 2016|archive-url=https://web.archive.org/web/20160919171319/https://www.washingtonpost.com/news/wonk/wp/2014/11/17/new-york-city-unveils-the-payphone-of-the-future-and-it-does-a-whole-lot-more-than-make-phone-calls/|url-status=live}}</ref><ref name="NYCGov-MayorAnnouncesWinner-20142">{{cite news|date=17 November 2014|title=De Blasio Administration Announces Winner of Competition to Replace Payphones with Five-Borough Wi-Fi Network|work=[[nyc.gov]]|publisher=[[Government of New York City]]|url=http://www1.nyc.gov/office-of-the-mayor/news/923-14/de-blasio-administration-winner-competition-replace-payphones-five-borough|access-date=17 November 2014|archive-date=7 June 2018|archive-url=https://web.archive.org/web/20180607153357/http://www1.nyc.gov/office-of-the-mayor/news/923-14/de-blasio-administration-winner-competition-replace-payphones-five-borough|url-status=live}}</ref><ref name="NYDailyNews-PayphonesReplaced-20162">{{cite news|last1=Alba|first1=Alejandro|date=5 January 2016|title=New York to start replacing payphones with Wi-Fi kiosks|work=[[New York Daily News]]|url=http://www.nydailynews.com/news/national/new-york-start-replacing-payphone-wi-fi-kiosks-article-1.2485429|access-date=26 January 2016|archive-date=24 June 2017|archive-url=https://web.archive.org/web/20170624191512/http://www.nydailynews.com/news/national/new-york-start-replacing-payphone-wi-fi-kiosks-article-1.2485429|url-status=live}}</ref> The [[UK]] has planned a similar project across major cities of the country, with the project's first implementation in the [[London Borough of Camden]].<ref>{{Cite web|last=McCormick|first=Rich|date=25 October 2016|title=Link brings its free public Wi-Fi booths from New York to London|url=https://www.theverge.com/2016/10/25/13401348/link-public-wi-fi-kiosk-london|access-date=25 July 2021|website=The Verge|language=en|archive-date=26 December 2016|archive-url=https://web.archive.org/web/20161226145341/http://www.theverge.com/2016/10/25/13401348/link-public-wi-fi-kiosk-london|url-status=live}}</ref>
Officials in South Korea's capital [[Seoul]] were 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 was planning to grant leases to KT, [[LG]] Telecom, and SK Telecom. The companies were supposed to invest $44 million in the project, which was to be completed in 2015.<ref name="Voice of America">{{cite web|url=https://blogs.voanews.com/breaking-news/2011/06/15/seoul-moves-to-provide-free-city-wide-wifi-service/|title=Seoul Moves to Provide Free City-Wide WiFi Service|date=15 June 2011|website=[[Voice of America]]|archive-url=https://web.archive.org/web/20121110050549/http://blogs.voanews.com/breaking-news/2011/06/15/seoul-moves-to-provide-free-city-wide-wifi-service/|archive-date=10 November 2012|url-status=dead|access-date=1 April 2012}}</ref>{{update inline|date=September 2023}}
=== Geolocation ===
[[Wi-Fi positioning system]]s use known positions of Wi-Fi hotspots to identify a device's ___location.<ref name="KolodziejHjelm2017">{{cite book|author1=Krzysztof W. Kolodziej|author2=Johan Hjelm|title=Local Positioning Systems: LBS Applications and Services|url=https://books.google.com/books?id=aV3LBQAAQBAJ|date=19 December 2017|publisher=CRC Press|isbn=978-1-4200-0500-4|access-date=6 October 2019|archive-date=17 January 2023|archive-url=https://web.archive.org/web/20230117221756/https://books.google.com/books?id=aV3LBQAAQBAJ|url-status=live}}</ref><ref>.{{cite journal |last1=Wang |first1=C. |last2=Zheng |first2=X. |last3=Chen |first3=Y. |last4=Yang |first4=J. |date=September 2017 |title=Locating Rogue Access Point Using Fine-Grained Channel Information |journal=IEEE Transactions on Mobile Computing |volume=16 |issue=9 |pages=2560–2573 |doi=10.1109/TMC.2016.2629473 |issn=1558-0660 |doi-access=free}}</ref><ref>{{cite web |title=Cisco Prime Network Control System Configuration Guide, Release 1.0 - Chapter 6: Monitoring Maps [Cisco Prime Network Control System Series Appliances] |url=https://www.cisco.com/c/en/us/td/docs/wireless/ncs/1-0/configuration/guide/NCS10cg/maps.html |access-date=19 December 2020 |website=Cisco}}</ref> It is used when [[GPS]] isn't suitable due to issues like signal interference or slow satellite acquisition.<ref>Magda Chelly, Nel Samama. Detecting visibility in heterogeneous simulated environments for positioning purposes. IPIN 2010: International Conference on Indoor Positioning and Indoor Navigation, Sep 2010, Hoenggerberg, Switzerland. ⟨hal-01345039⟩ [https://hal.archives-ouvertes.fr/hal-01345039]</ref> This includes assisted [[GPS]], urban hotspot databases, and indoor positioning systems.<ref>Magda Chelly, Nel Samama. New techniques for indoor positioning, combining deterministic and estimation methods. ENC-GNSS 2009: European Navigation Conference – Global Navigation Satellite Systems, May 2009, Naples, Italy. pp.1 – 12. hal-01367483 [https://hal.archives-ouvertes.fr/hal-01367483/]</ref> Wi-Fi positioning relies on measuring signal strength ([[RSSI]]) and fingerprinting.<ref name=":2"/><ref>Y. Chen and H. Kobayashi, "Signal strength based indoor geolocation," in Proceedings of the IEEE International Conference on Communications (ICC ’02), vol. 1, pp. 436–439, New York, NY, USA, April–May 2002.</ref><ref name=":7">{{Cite book|last1=Youssef|first1=M. A.|last2=Agrawala|first2=A.|last3=Shankar|first3=A. Udaya|title=Proceedings of the First IEEE International Conference on Pervasive Computing and Communications, 2003. (PerCom 2003) |chapter=WLAN ___location determination via clustering and probability distributions |date=2003-03-01|pages=143–150|doi=10.1109/PERCOM.2003.1192736|isbn=978-0-7695-1893-0|citeseerx=10.1.1.13.4478|s2cid=2096671 }}</ref><ref name=":8">{{Cite book|last1=Youssef|first1=Moustafa|last2=Youssef|first2=Adel|last3=Rieger|first3=Chuck|last4=Shankar|first4=Udaya|last5=Agrawala|first5=Ashok|title=Proceedings of the 4th international conference on Mobile systems, applications and services |chapter=PinPoint |date=2006-01-01|series=MobiSys '06|___location=New York, NY, USA|publisher=ACM|pages=165–176|doi=10.1145/1134680.1134698|isbn=978-1595931955|s2cid=232045615 }}</ref> Parameters like [[SSID]] and MAC address are crucial for identifying access points. The accuracy depends on nearby access points in the database. Signal fluctuations can cause errors, which can be reduced with noise-filtering techniques. For low precision, integrating Wi-Fi data with geographical and time information has been proposed.<ref>{{cite journal|last1=Danalet|first1=Antonin|last2=Farooq|first2=Bilal|last3=Bierlaire|first3=Michel|title=A Bayesian approach to detect pedestrian destination-sequences from WiFi signatures|journal=Transportation Research Part C: Emerging Technologies|volume=44|pages=146–170|doi=10.1016/j.trc.2014.03.015|url=http://infoscience.epfl.ch/record/199471|year=2014|bibcode=2014TRPC...44..146D }}</ref><ref name=":1"/>
The [[Wi-Fi RTT]] capability introduced in [[IEEE 802.11mc]] allows for positioning based on round trip time measurement, an improvement over the RSSI method.<ref>{{citation |url=https://www.sciencedirect.com/science/article/abs/pii/S1574119221000687 |title=Accurate indoor positioning using IEEE 802.11mc round trip time |date=2021 |doi=10.1016/j.pmcj.2021.101416 |access-date=2023-10-24 |last1=Hashem |first1=Omar |last2=Harras |first2=Khaled A. |last3=Youssef |first3=Moustafa |journal=Pervasive and Mobile Computing |volume=75 |s2cid=236299935 |url-access=subscription }}</ref> The [[IEEE 802.11az]] standard promises further improvements in geolocation accuracy.<ref>{{cite press release |url=https://standards.ieee.org/beyond-standards/newly-released-ieee-802-11az-standard-improving-wi-fi-___location-accuracy-is-set-to-unleash-a-new-wave-of-innovation/ |title=Newly Released IEEE 802.11az Standard Improving Wi-Fi Location Accuracy is Set to Unleash a New Wave of Innovation |access-date=2023-10-24}}</ref><ref>{{cite web |url=https://blogs.arubanetworks.com/solutions/wi-fi-___location-based-services-how-did-we-get-here/ |title=Wi-Fi ___location-based services: How did we get here? |date=27 February 2023 |access-date=2023-10-24}}</ref>
=== Motion detection ===
[[Wi-Fi sensing]] is used in applications such as [[motion detection]] and [[gesture recognition]].<ref>{{Cite journal|last1=Khalili|first1=Abdullah|last2=Soliman|first2=Abdel-Hamid|last3=Asaduzzaman|first3=Md|last4=Griffiths|first4=Alison|date=March 2020|title=Wi-Fi sensing: applications and challenges|journal=The Journal of Engineering|language=en|volume=2020|issue=3|pages=87–97|doi=10.1049/joe.2019.0790|issn=2051-3305|doi-access=free|arxiv=1901.00715}}</ref>
== Operational principles ==
Wi-Fi stations communicate by sending each other [[data packet]]s, blocks of data individually sent and delivered over radio on various channels. As with all radio, this is done by the [[modem|modulation and demodulation]] of [[carrier wave]]s. Different versions of Wi-Fi use different techniques, 802.11b uses [[direct-sequence spread spectrum]] on a single carrier, whereas 802.11a, Wi-Fi 4, 5 and 6 use [[orthogonal frequency-division multiplexing]].<ref>Cisco Systems, Inc. White Paper Capacity, Coverage, and Deployment Considerations for IEEE 802.11g</ref><ref name="oreilly-802.11ac">{{cite web |url=http://chimera.labs.oreilly.com/books/1234000001739/ch04.html |work=802.11ac: A Survival Guide |first1=Matthew S. |last1=Gast |date=2013 |title=Chapter 4. Beamforming in 802.11ac |publisher=O'Reilly Atlas |access-date=17 April 2014 |archive-url=https://web.archive.org/web/20170703105148/http://chimera.labs.oreilly.com/books/1234000001739/ch04.html |archive-date=3 July 2017 |url-status=dead }}</ref>
Channels are used [[half duplex]]<ref>{{Cite web|date=23 January 2020|title=Why can't WiFi work as full duplex while 3G and 4G can|url=https://community.meraki.com/t5/Wireless-LAN/Why-can-t-WiFi-work-as-full-duplex-while-3G-and-4G-can/m-p/74017#M11290|access-date=19 September 2020|website=Meraki Community |language=en|archive-date=17 October 2021|archive-url=https://web.archive.org/web/20211017103935/https://community.meraki.com/t5/Wireless-LAN/Why-can-t-WiFi-work-as-full-duplex-while-3G-and-4G-can/m-p/74017#M11290|url-status=live}}</ref><ref>{{Cite web|title=Bad Info Is Nothing New for WLAN- Don't Believe "Full Duplex" in Wi-Fi 6|url=https://www.toolbox.com/tech/it-strategy/blogs/bad-info-is-nothing-new-for-wlan-dont-believe-full-duplex-in-wi-fi-6-082619/ |date= August 26, 2019 |first1=Lee |last1=Badman |access-date=19 September 2020|website=Toolbox|language=en-US|archive-date=19 November 2021|archive-url=https://web.archive.org/web/20211119071542/https://www.toolbox.com/tech/it-strategy/blogs/bad-info-is-nothing-new-for-wlan-dont-believe-full-duplex-in-wi-fi-6-082619/|url-status=live}}</ref> and can be [[Time-division multiple access|time-shared]] by multiple networks. Any packet sent by one computer is locally received by stations tuned to that channel, even if that information is intended for just one destination.{{Efn|This ''one speaks, all listen'' property is a security weakness of shared-medium Wi-Fi since a node on a Wi-Fi network can eavesdrop on all traffic on the wire if it so chooses.}} Stations typically ignore information not addressed to them.{{Efn|name=promiscuous|Unless it is put into [[promiscuous mode]].}} The use of the same channel also means that the data bandwidth is shared, so for example, available throughput to each device is halved when two stations are actively transmitting.
As with other IEEE 802 LANs, stations come programmed with a globally unique 48-bit MAC address.{{Efn|In some cases, the factory-assigned address can be overridden, either to avoid an address change when an adapter is replaced or to use [[locally administered address]]es.}} The MAC addresses are used to specify both the destination and the source of each data packet. 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 scheme known as [[carrier-sense multiple access with collision avoidance]] (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,<ref name="federalstandard">{{cite web |url=http://www.its.bldrdoc.gov/fs-1037/fs-1037c.htm |title=Federal Standard 1037C |website=Institute for Telecommunication Sciences |date=August 7, 1996 |access-date=9 September 2012 |archive-date=2 March 2009 |archive-url=https://web.archive.org/web/20090302235918/http://www.its.bldrdoc.gov/fs-1037/fs-1037c.htm |url-status=dead }}</ref><ref name="atis">{{cite web |url=http://www.atis.org/tg2k/ |title=ATIS Telecom Glossary 2007 |id=ATIS-0100523.2007 |website=Alliance for Telecommunications Industry Solutions |access-date=9 September 2012 |url-status=dead |archive-url=https://web.archive.org/web/20080302071329/http://www.atis.org/tg2k/ |archive-date=2 March 2008 }}</ref> but then transmit their packet data in its entirety. CSMA/CA cannot completely prevent collisions, as two stations may sense the channel to be idle at the same time and thus begin transmission simultaneously. A collision happens when a station receives signals from multiple stations 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 ===
{{Main|List of WLAN channels}}
The 802.11 standard provides several distinct [[radio frequency]] ranges for use in Wi-Fi communications: 900 [[MHz]], 2.4 GHz, 3.6 GHz, 4.9 GHz, 5 GHz, 6 GHz and 60 GHz [[band (radio)|bands]].<ref>{{Cite web |url=https://www.radio-electronics.com/info/wireless/wi-fi/80211-channels-number-frequencies-bandwidth.php |title=Wi-Fi Channels, Frequencies, Bands & Bandwidths |website=Electronics Notes |language=en |access-date=18 August 2018 |archive-date=16 February 2018 |archive-url=https://web.archive.org/web/20180216081725/https://www.electronics-notes.com/articles/connectivity/wifi-ieee-802-11/channels-frequencies-bands-bandwidth.php |url-status=live }}</ref><ref>{{cite book | url=https://ieeexplore.ieee.org/document/7786995 | publisher=[[IEEE]] | date=14 December 2016 | doi=10.1109/IEEESTD.2016.7786995| isbn=978-1-5044-3645-8 | title=IEEE Standard for Information technology—Telecommunications and information exchange between systems Local and metropolitan area networks—Specific requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications }}</ref><ref>{{Cite news|url=https://www.lifewire.com/wireless-standards-802-11a-802-11b-g-n-and-802-11ac-816553|title=802.11 WiFi Standards Explained|work=Lifewire|access-date=18 August 2018|language=en|archive-date=12 December 2018|archive-url=https://web.archive.org/web/20181212063416/https://www.lifewire.com/wireless-standards-802-11a-802-11b-g-n-and-802-11ac-816553|url-status=live}}</ref> Each range is divided into a multitude of [[Channel (communications)|channels]]. 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 neighbouring channels to be bonded together to form a wider channel for higher throughput.
Countries apply their own regulations to the allowable channels, allowed users and maximum power levels within these frequency ranges. 802.11b/g/n can use the 2.4 GHz band, operating in the United States under FCC [[Part 15]] rules and regulations. In this frequency band, equipment may occasionally suffer [[Interference (communication)|interference]] from microwave ovens,<ref name="scienceabc" /> [[cordless telephone]]s, [[USB 3.0]] hubs,<ref>{{cite web |url= http://www.usb.org/developers/docs/whitepapers/327216.pdf |title=USB 3.0 Radio Frequency Interference Impact on 2.4 GHz Wireless Devices |website=USB.org |publisher=USB Implementers Forum |date=April 2012 |access-date=14 October 2019}}</ref> [[Bluetooth]] and other devices.<ref name="wired">{{Cite magazine|url=https://www.wired.com/2010/09/wireless-explainer/|title=Why Everything Wireless Is 2.4 GHz|magazine=WIRED|access-date=18 August 2018|language=en-US|archive-date=26 July 2018|archive-url=https://web.archive.org/web/20180726115300/https://www.wired.com/2010/09/wireless-explainer/|url-status=live}}</ref>
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).
802.11a/h/j/n/ac/ax can use the [[U-NII|5 GHz U-NII band]], which, for much of the world, offers at least 23 non-overlapping 20 MHz channels. This is in contrast to the 2.4 GHz frequency band where the channels are only 5 MHz wide. In general, lower frequencies have longer 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 bandwidth use. Additionally, they have gained the ability to [[Link aggregation|aggregate]] channels together to gain still more throughput where the bandwidth for additional channels is available. 802.11n allows for double radio spectrum bandwidth (40 MHz) per channel compared to [[802.11a]] or 802.11g (20 MHz). 802.11n can be set to limit itself to 20 MHz bandwidth to prevent interference in dense communities.<ref>{{Cite web|url=https://www.cisco.com/c/en/us/products/collateral/wireless/aironet-1250-series/design_guide_c07-693245.html#_Toc309331071|title=802.11n Data Rates Dependability and scalability|publisher=[[Cisco]]|archive-url=https://web.archive.org/web/20170705034144/http://www.cisco.com/c/en/us/products/collateral/wireless/Aironet-1250-series/design_guide_c07-693245.html#_Toc309331071|archive-date=5 July 2017|url-status=live|access-date=20 November 2017}}</ref> In the 5 GHz band, 20 MHz, 40 MHz, 80 MHz, and 160 MHz channels are permitted with some restrictions, giving much faster connections.
{|style="margin: 0 auto;"
| [[File:2.4 GHz spectrum example Screenshot.png|thumb|An example of 2.4 GHz Wi-Fi spectrum]]
| [[File:5 GHz Wi-Fi spectrum screenshot.png|thumb|An example of 5 GHz Wi-Fi spectrum]]
| [[File:Netgear-Nighthawk-AC1900-WiFi-Router.jpg|thumb|upright| This [[Netgear]] Wi-Fi router contains dual bands for transmitting the 802.11 standards across the 2.4 and 5 GHz spectrums and supports MIMO.]]
| [[File:Huawei 4G+ Modem.jpg|thumb|upright| A dual-band cellular 4G+ Wi-Fi modem by Huawei]]
|}
=== Communication stack ===
{{Main|IEEE 802|IEEE 802.11}}
[[File:802.11 frame.png|alt=|right|frameless|622x622px|Generic 802.11 Frame]]
Wi-Fi is part of the IEEE 802 protocol family. The data is organized into [[802.11 frame types|802.11 frames]] that are very similar to [[Ethernet frame]]s at the data link layer, but with extra address fields. MAC addresses are used as [[network address]]es for routing over the LAN.<ref name="IEEE 802.3 Clause 3.1.1">{{cite web| url = http://standards.ieee.org/getieee802/download/802.3-2012_section1.pdf| title = 3.1.1 Packet format| work = IEEE Standard for Ethernet, 802.3-2012 – section one| date = 28 December 2012| access-date = 6 July 2014| page = 53| url-status=dead| archive-url = https://web.archive.org/web/20141021020414/http://standards.ieee.org/getieee802/download/802.3-2012_section1.pdf| archive-date = 21 October 2014}}</ref>
Wi-Fi's MAC and [[physical layer]] (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, [[IEEE 802.11y-2008|3.6]], 5, 6, or [[IEEE 802.11ad|60 GHz]] frequency bands. They are created and maintained by the IEEE LAN/MAN Standards Committee ([[IEEE 802]]). The base version of the standard was released in 1997 and has had 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 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.<ref>{{cite web|url=http://www.gadgetreview.com/what-is-wifi-what-does-wifi-stand-for-how-does-it-work|title=What Does WiFi Stand For and How Does Wifi Work?|last=Stobing|first=Chris|date=17 November 2015|website=GadgetReview|archive-url=https://web.archive.org/web/20151201045951/http://www.gadgetreview.com/what-is-wifi-what-does-wifi-stand-for-how-does-it-work|archive-date=1 December 2015|url-status=live|access-date=18 November 2015}}</ref> 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]] mechanism. Because of this, for Wi-Fi, the [[Logical Link Control]] (LLC) specified by [[IEEE 802.2]] employs Wi-Fi's [[media access control]] (MAC) protocols to manage retries without relying on higher levels of the protocol stack.<ref>{{cite book|last1=Geier|first1=Jim|title=Overview of the IEEE 802.11 Standard|url=http://www.informit.com/articles/article.aspx?p=24411&seqNum=7|publisher=InformIT|access-date=8 April 2016|url-status=live|archive-url=https://web.archive.org/web/20160420043213/http://www.informit.com/articles/article.aspx?p=24411&seqNum=7|archive-date=20 April 2016|date=6 December 2001}}</ref>
For internetworking purposes, Wi-Fi is usually [[protocol layering|layered]] as a [[link layer]]{{efn|The link layer is equivalent to the physical and data link layers of the [[OSI model]].}} below the [[internet layer]] of the [[Internet Protocol]]. This means that nodes have an associated [[internet address]] and, with suitable connectivity, this allows full Internet access.
===Modes===
====Infrastructure====
[[File:Wi-Fi.gif|thumb|A Wi-Fi network in infrastructure mode. The print job is sent from the computer via the AP to the printer.]]
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 limits issues associated with the [[hidden node problem]] and 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 [[wireless ad hoc network|''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]] in his 1996 patent of wireless ad hoc routing,<ref>{{Cite patent|country=US|number=5987011|title=Routing Method for Ad-Hoc Mobile Networks|status=|pubdate=16 November 1999|gdate=|invent1=Toh|inventor1-first=Chai Keong|inventorlink=Chai Keong Toh}}</ref> implemented on Lucent WaveLAN 802.11a wireless on IBM [[ThinkPad]]s over a size nodes scenario spanning a region of over a mile. The success was recorded in ''Mobile Computing'' magazine (1999)<ref>{{Cite web|url=http://www.mobileinfo.com/education/magazines.htm|title=Mobile Computing Magazines and Print Publications|website=www.mobileinfo.com|url-status=live|archive-url=https://web.archive.org/web/20160426220723/http://www.mobileinfo.com/education/magazines.htm|archive-date=26 April 2016|access-date=19 December 2017}}</ref> and later published formally in ''[[IEEE Transactions on Wireless Communications]]'', 2002<ref>{{cite journal|last1=Toh|first1=C.-K|author-link=Chai Keong Toh|last2=Delwar|first2=M.|last3=Allen|first3=D.|date=7 August 2002|title=Evaluating the Communication Performance of an Ad Hoc Mobile Network|journal=[[IEEE Transactions on Wireless Communications]]|volume=1|issue=3|pages=402–414|doi=10.1109/TWC.2002.800539}}</ref> and ''ACM SIGMETRICS Performance Evaluation Review'', 2001.<ref>{{cite journal|last1=Toh|first1=C.-K|author-link=Chai Keong Toh|last2=Chen|first2=Richard|last3=Delwar|first3=Minar|last4=Allen|first4=Donald|date=2001|title=Experimenting with an Ad Hoc Wireless Network on Campus: Insights & Experiences|url=http://ftp.math.utah.edu/pub/tex/bib/toc/sigmetrics.html|journal=ACM SIGMETRICS Performance Evaluation Review|volume=28|issue=3|pages=21–29|doi=10.1145/377616.377622|s2cid=1486812|access-date=8 October 2021|archive-date=2 December 2021|archive-url=https://web.archive.org/web/20211202183049/http://ftp.math.utah.edu/pub/tex/bib/toc/sigmetrics.html|url-status=live|url-access=subscription}}</ref>
This wireless ad hoc network mode has proven popular with [[multiplayer video game]]s on [[handheld game console]]s, such as the [[Nintendo DS]] and [[PlayStation Portable]]. It is also popular on [[digital camera]]s, and other [[consumer electronics devices]]. Some devices can also share their Internet connection using ad hoc, becoming hotspots or [[virtual router]]s.<ref>{{cite web|url=https://techsansar.com/internetworking/wireless-home-networking-virtual-wifi-hotspot/|title=Wireless Home Networking with Virtual WiFi Hotspot|last=Subash|date=24 January 2011|website=Techsansar|archive-url=https://web.archive.org/web/20110830150439/http://techsansar.com/internetworking/wireless-home-networking-virtual-wifi-hotspot-2946/|archive-date=30 August 2011|url-status=live|access-date=14 October 2011}}</ref>
Similarly, the Wi-Fi Alliance promotes the specification [[Wi-Fi Direct]] for file transfers and media sharing through a new discovery and security methodology.<ref>{{cite web|url=http://www.networkworld.com/news/2009/101409-wi-fi-direct.html?hpg1=bn|title=Wi-Fi Direct allows device-to-device links|last=Cox|first=John|date=14 October 2009|website=[[Network World]]|archive-url=https://web.archive.org/web/20091023052219/http://www.networkworld.com/news/2009/101409-wi-fi-direct.html?hpg1=bn|archive-date=23 October 2009|url-status=dead}}</ref> Wi-Fi Direct launched in October 2010.<ref>{{cite web|url=http://www.wi-fi.org/news-events/newsroom/wi-fi-gets-personal-groundbreaking-wi-fi-direct-launches-today|title=Wi-Fi gets personal: Groundbreaking Wi-Fi Direct launches today|date=25 October 2010|publisher=[[Wi-Fi Alliance]]|archive-url=https://web.archive.org/web/20150626120701/http://www.wi-fi.org/news-events/newsroom/wi-fi-gets-personal-groundbreaking-wi-fi-direct-launches-today|archive-date=26 June 2015|url-status=live|access-date=25 June 2015}}</ref>
Another mode of direct communication over Wi-Fi is [[Tunneled Direct Link Setup]] (TDLS), which enables two devices on the same Wi-Fi network to communicate directly, instead of via the access point.<ref>{{cite web|url=http://www.wi-fi.org/knowledge-center/faq/what-is-wi-fi-certified-tdls|title=What is Wi-Fi Certified TDLS?|publisher=[[Wi-Fi Alliance]]|archive-url=https://web.archive.org/web/20141108145755/http://www.wi-fi.org/knowledge-center/faq/what-is-wi-fi-certified-tdls|archive-date=8 November 2014|url-status=dead}}</ref>
=== Multiple access points ===
[[File:802.11 Beacon frame.gif|thumb|Access points send out [[beacon frame]]s to announce the presence of networks.]]
An [[Extended Service Set]] 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.<ref>{{citation
|last=Edney
|first=Jon
|year=2004
|chapter=What is an ESS?
|title=IEEE 802 LAN/MAN Standards Committee Meeting, July 2004
|___location=Piscataway, New Jersey
|publisher=Institute of Electrical and Electronics Engineers
|chapter-url=http://www.ieee802.org/21/doctree/2004_Meeting_Docs/2004-07_meeting_docs/21-04-0105-00-0000-what_ess.ppt
|page=8}}</ref>
Increasing the number of Wi-Fi access points for a network provides [[Redundancy (engineering)|redundancy]], better range, support for fast [[handover]], and increased overall network capacity by using more channels or by defining smaller [[cellular network|cells]]. 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 networking|mesh]] topologies.<ref>{{cite web|url=https://newscutzy.com/windows/fix-wifi-connected-but-no-internet-access/|title=Fix WiFi Connected But No Internet Access On Windows 11/10/8/7|access-date=25 June 2020|publisher=newscutzy.com|date=3 December 2021|language=english|author=Mohsin Beg|archive-date=24 June 2021|archive-url=https://web.archive.org/web/20210624202339/https://newscutzy.com/windows/fix-wifi-connected-but-no-internet-access/|url-status=live}}</ref>
== Performance ==
{{See also|Long-range Wi-Fi}}
Wi-Fi operational range depends on factors such as the frequency band, modulation technique, [[transmitter power output]], receiver sensitivity, antenna gain and type, and propagation and interference characteristics in the environment. At longer distances, speed is typically 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]] (100 mW).
Wi-Fi, however, has higher power compared to some other standards designed to support [[wireless personal area network]] applications. For example, Bluetooth provides a much shorter [[Radio propagation|propagation]] range between 1 and 100 metres (1 and 100 yards)<ref>{{cite web|url=https://janmagnet.files.wordpress.com/2008/07/comparison-ieee-802-standards.pdf|title=Comparison of the IEEE 802.11, 802.15.1,802.15.4, and 802.15.6 wireless standards|last=Tjensvold|first=Jan Magne|date=18 September 2007|archive-url=https://web.archive.org/web/20130720054917/http://janmagnet.files.wordpress.com/2008/07/comparison-ieee-802-standards.pdf|archive-date=20 July 2013|url-status=live|access-date=26 April 2013}} section 1.2 (scope)</ref> and so in general has a lower power consumption. Other low-power technologies such as [[Zigbee]] 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===
On wireless routers with detachable antennas, it is possible to improve range by fitting upgraded antennas. An access point compliant with either [[IEEE 802.11#802.11b|802.11b]] or 802.11g, using the stock [[omnidirectional antenna]] might have a range of 0.1 km. The same radio with an external semi-parabolic antenna (15 dB [[Gain (antenna)|gain]]) with a similarly equipped receiver at the far end might have a range of over 32 km.
Higher gain rating ([[dBi]]) indicates deviation from a theoretical, perfect [[isotropic radiator]] toward a [[directional antenna]], 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.<ref>{{cite web|url=http://www.dslreports.com/forum/r15405199-Somebody-explain-dBi|title=Somebody explain dBi – Wireless Networking |work=DSL Reports Forums |url-status=live|archive-url=https://web.archive.org/web/20140809101928/http://www.dslreports.com/forum/r15405199-Somebody-explain-dBi|archive-date=9 August 2014}}</ref> 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. This assumes that radiation in the vertical direction is not useful for communications.
{| style="margin: 0 auto;"
| [[File:Wifi point to point.jpg|thumb|upright|Parabolic dishes are [[Directional antenna|directional]] and can give much greater range than [[omnidirectional antenna]]s.]]
| [[File:Yagi-Uda antenna for Wi-Fi on Router.jpg|thumb|[[Yagi–Uda antenna]]s, widely used for television reception, are relatively compact at Wi‑Fi wavelengths.]]
| [[File:Antenna of wireless network interface controller Gigabyte GC-WB867D-I - 2018-05-18.jpg|thumb|Antenna of a Gigabyte GC-WB867D-I wireless network interface controller. Simple stick-like antennas have omnidirectional reception and relatively low range of 20 metres (yards) or so.]]
|}
=== MIMO (multiple-input and multiple-output) ===
{{Main|MIMO}}
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]] on the same frequency bands, giving higher speeds and more than doubled range.<ref name=wifiplanet>{{cite web|url=http://www.wi-fiplanet.com/tutorials/article.php/3680781 |title=802.11n Delivers Better Range |date=31 May 2007 |work=Wi-Fi Planet |url-status=dead |archive-url=https://web.archive.org/web/20151108080354/http://www.wi-fiplanet.com/tutorials/article.php/3680781 |archive-date=8 November 2015 }}</ref>
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. This standard uses several signal processing techniques such as multi-user MIMO and {{times|4x4}} spatial multiplexing streams, and wide channel bandwidth (160 MHz) to achieve its gigabit throughput.<!--[[User:Kvng/RTH]]-->
===Radio propagation===
With Wi-Fi signals [[Line-of-sight propagation|line-of-sight]] usually works best, but signals can transmit, absorb, reflect, [[refract]], [[diffract]] and [[fading|up and down fade]] through and around structures, both man-made and natural. Wi-Fi signals are very strongly affected by metallic structures (including [[rebar]] in concrete, [[Window insulation#Low-e coatings|low-e coatings]] in glazing), rock structures (including [[marble]]) 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.<ref>{{cite web
|url = http://www.alyrica.net/node/20
|title = WiFi Mapping Software:Footprint
|publisher = Alyrica Networks
|access-date = 27 April 2008
|url-status = live
|archive-url = https://web.archive.org/web/20090502175411/http://www.alyrica.net/node/20
|archive-date = 2 May 2009
}}</ref> 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 {{convert|382|km|mi|abbr=on}} in June 2007, held by Ermanno Pietrosemoli and EsLaRed of Venezuela, transferring about 3 MB of data between the mountain-tops of [[Pico El Águila|El Águila]] and Platillon.<ref>
{{cite web
|url = https://interred.wordpress.com/2007/06/18/ermanno-pietrosemoli-has-set-a-new-record-for-the-longest-communication-wi-fi-link/
|title = Ermanno Pietrosemoli has set a new record for the longest communication Wi-Fi link
|last = Kanellos
|first = Michael
|date = 18 June 2007
|archive-url = https://web.archive.org/web/20080321104324/http://interred.wordpress.com/2007/06/18/ermanno-pietrosemoli-has-set-a-new-record-for-the-longest-communication-wi-fi-link/
|archive-date = 21 March 2008
|url-status = live
|access-date = 10 March 2008
}}</ref><ref>
{{cite web
|url = https://www.apc.org/en/news/strategic/world/wireless-technology-irreplaceable-providing-access
|title = Wireless technology is irreplaceable for providing access in remote and scarcely populated regions
|last = Toulouse
|first = Al
|date = 2 June 2006
|publisher = [[Association for Progressive Communications]]
|archive-url = https://web.archive.org/web/20090202095345/http://www.apc.org/en/news/strategic/world/wireless-technology-irreplaceable-providing-access
|archive-date = 2 February 2009
|url-status = live
|access-date = 10 March 2008
}}</ref> The [[Swedish National Space Agency]] transferred data {{convert|420|km|mi|abbr=on}}, using 6 watt amplifiers to reach an overhead [[stratospheric balloon]].<ref>{{cite web|url=https://yourgadgetgeek.com/media_file/long_distance_wiFi_trial.pdf|title=Long Distance WiFi Trial|last=Pietrosemoli|first=Ermanno|date=18 May 2007|archive-url=https://web.archive.org/web/20160305165645/http://www.wifiadvies.be/wp-content/uploads/2015/11/200705_long_distance_wiFi_trial.pdf|archive-date=5 March 2016|url-status=live|access-date=10 March 2008}}</ref>
=== Interference ===
{{Further|Electromagnetic interference at 2.4 GHz#Wi-Fi}}
[[File:Wi-Fi Allocations 4.gif|thumb|upright=0.9|Network planning frequency allocations for North America and Europe. Using these types of frequency allocations can help minimize co-channel and adjacent-channel interference.]]
[[File:Co-Channel Wi-Fi Interference 01.png|thumb|In the 2.4 GHz wavebands as well as others, transmitters straddle multiple channels. Overlapping channels can suffer from interference unless this is a small portion of the total received power.]]
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]] (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]] and [[exposed node problem]].<ref>{{Cite journal|last1=Chakraborty|first1=Sandip|last2=Nandi|first2=Sukumar|last3=Chattopadhyay|first3=Subhrendu|date=22 September 2015|title=Alleviating Hidden and Exposed Nodes in High-Throughput Wireless Mesh Networks|journal=[[IEEE Transactions on Wireless Communications]]|volume=15|issue=2|pages=928–937|doi=10.1109/TWC.2015.2480398|s2cid=2498458 }}</ref>
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]]). 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{{snd}}much less than reusing channels (which causes [[co-channel interference]]){{snd}}if transmitters are at least a few metres apart.<ref name="villegas">{{cite book |chapter=Effect of Adjacent-Channel Interference in IEEE 802.11 WLANs |first1=Eduard Garcia |last1=Villegas |first2=Elena |last2=Lopez-Aguilera |first3=Rafael |last3=Vidal |first4=Josep |last4=Paradells |title=2007 2nd International Conference on Cognitive Radio Oriented Wireless Networks and Communications |date=2007 |pages=118–125 |doi=10.1109/CROWNCOM.2007.4549783 |hdl=2117/1234 |isbn=978-1-4244-0814-6 |s2cid=1750404 }}</ref> In Europe and Japan where channel 13 is available, using Channels 1, 5, 9, and 13 for [[IEEE 802.11#802.11g|802.11g]] and [[IEEE 802.11#802.11n|802.11n]] is viable and [[IEEE 802.11#Channels and frequencies|recommended]].
However, multiple 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]] (SNR) between access points. These issues can become a problem in high-density areas, such as large apartment complexes or office buildings with multiple Wi-Fi access points.<ref>den Hartog, F., Raschella, A., Bouhafs, F., Kempker, P., Boltjes, B., & Seyedebrahimi, M. (November 2017). [http://unsworks.unsw.edu.au/fapi/datastream/unsworks:50254/bin458a10d9-f568-479c-a9b5-5c185ef64e78?view=true A Pathway to solving the Wi-Fi Tragedy of the Commons in apartment blocks] {{Webarchive|url=https://web.archive.org/web/20200713111300/http://unsworks.unsw.edu.au/fapi/datastream/unsworks:50254/bin458a10d9-f568-479c-a9b5-5c185ef64e78?view=true |date=13 July 2020 }}. In 2017 27th International Telecommunication Networks and Applications Conference (ITNAC) (pp. 1–6). IEEE.</ref>
Other devices use the 2.4 GHz band:<ref name="wired" /> microwave ovens, ISM band devices, [[security camera]]s, Zigbee devices, Bluetooth devices, [[video sender]]s, cordless phones, [[baby monitor]]s,<ref>{{cite web|url=https://www.monitorshq.com/6-easy-steps-to-protect-your-baby-monitor-from-hackers/|title=6 Easy Steps To Protect Your Baby Monitor From Hackers|last=Caravan|first=Delia|date=12 September 2014|website=Baby Monitor Reviews HQ|archive-url=https://web.archive.org/web/20141018042051/https://www.monitorshq.com/6-easy-steps-to-protect-your-baby-monitor-from-hackers/|archive-date=18 October 2014|url-status=dead|access-date=12 September 2014}}</ref> and, in some countries, [[amateur radio]], all of which can cause significant additional interference. It is also an issue when municipalities<ref>{{cite web|url=https://computer.howstuffworks.com/municipal-wifi.htm|title=How Municipal WiFi Works|last=Wilson|first=Tracy V.|date=17 April 2006|website=[[HowStuffWorks]]|archive-url=https://web.archive.org/web/20080223120947/http://computer.howstuffworks.com/municipal-wifi.htm|archive-date=23 February 2008|url-status=live|access-date=12 March 2008}}</ref> 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.<ref>{{Cite web|url=https://www.networkworld.com/article/949170/wi-fi-hotspot-blocking-persists-despite-fcc-crackdown.html|title=Wi-Fi hotspot blocking persists despite FCC crackdown|last=Brown|first=Bob|date=10 March 2016|website=[[Network World]]|archive-url=https://web.archive.org/web/20190227033935/https://www.networkworld.com/article/3042454/wi-fi-hotspot-blocking-persists-despite-fcc-crackdown.html|archive-date=27 February 2019|url-status=live}}</ref>
=== 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]]).
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.<ref>{{cite conference |title=Towards Energy-Awareness in Managing Wireless LAN Applications |url=https://www.researchgate.net/publication/241631429 |publisher=IEEE/IFIP NOMS |date=2012 |conference=IEEE/IFIP Network Operations and Management Symposium |access-date=11 August 2014 |archive-date=13 August 2014 |archive-url=https://web.archive.org/web/20140813094612/http://www.researchgate.net/publication/241631429_Towards_energy-awareness_in_managing_wireless_LAN_applications?ev=prf_pub |url-status=live }}</ref><ref>{{cite web |title=Application Level Energy and Performance Measurements in a Wireless LAN |url=https://www.researchgate.net/publication/224264522 |publisher=The 2011 IEEE/ACM International Conference on Green Computing and Communications |access-date=11 August 2014 |archive-date=13 August 2014 |archive-url=https://web.archive.org/web/20140813113706/http://www.researchgate.net/publication/224264522_Application_Level_Energy_and_Performance_Measurements_in_a_Wireless_LAN?ev=prf_pub |url-status=live }}</ref>
The same references apply to the attached throughput graphs, which show measurements of [[User Datagram Protocol|UDP]] 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.
{| style="margin: 0 auto;"
| [[File:Throughputenvelope80211g.png|thumb|upright=1.5|Graphical representation of Wi‑Fi application-specific performance envelope of 802.11g, which uses the {{nowrap|2.4 GHz}} band]]
| [[File:ThroughputEnvelope11n.png|thumb|upright=1.5|Graphical representation of Wi‑Fi application-specific performance envelope of 802.11n using a 40 MHz channel width in the {{nowrap|2.4 GHz}} band]]
|}
== Hardware ==
[[File:RouterBoard 112 with U.FL-RSMA pigtail and R52 miniPCI Wi-Fi card.jpg|thumb|An [[embedded system|embedded]] [[MikroTik#RouterBOARD|RouterBoard]] 112 with [[U.FL]]-[[SMA connector|RSMA]] pigtail and R52 [[Conventional PCI|mini PCI]] Wi-Fi card widely used by [[wireless]] Internet service providers ([[Wireless Internet service provider|WISPs]]) in the [[Czech Republic]]]]
[[File:3GN.jpg|thumb|OSBRiDGE 3GN – [[IEEE 802.11n-2009|802.11n]] access point and [[High-Speed Downlink Packet Access|UMTS/GSM]] gateway in one device]]
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 device|short-range]] [[wireless]] device. Wi-Fi devices are [[semiconductor device fabrication|fabricated]] on [[RF CMOS]] [[integrated circuit]] ([[RF circuit]]) chips.<ref>{{cite book |last1=Veendrick |first1=Harry J. M. |title=Nanometer CMOS ICs: From Basics to ASICs |date=2017 |publisher=Springer |isbn=9783319475974 |page=243 |url=https://books.google.com/books?id=Lv_EDgAAQBAJ&pg=PA243 |access-date=26 October 2019 |archive-date=17 January 2023 |archive-url=https://web.archive.org/web/20230117221755/https://books.google.com/books?id=Lv_EDgAAQBAJ&pg=PA243 |url-status=live }}</ref>
Since the early 2000s, manufacturers are building wireless network adapters into most laptops. The price of [[chipset]]s for Wi-Fi continues to drop, making it an economical networking option included in ever more devices.<ref>{{cite web|url=https://www.thedigitalworm.com/free-wifi-analyzer-apps/|title=Free WiFi Analyzer-Best Channel Analyzer Apps For Wireless Networks|date=8 June 2017|website=The Digital Worm|archive-url=https://web.archive.org/web/20170808000116/https://www.thedigitalworm.com/free-wifi-analyzer-apps/|archive-date=8 August 2017|url-status=usurped}}</ref>
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]]. Unlike [[mobile phone]]s, any standard Wi-Fi device works anywhere in the world.
=== Access point ===
[[File:Apple-Airport-Extreme-80211g-WiFi-Card.jpg|thumb|upright|An [[AirPort]] Wi‑Fi adapter, supporting 802.11g, from an Apple [[MacBook]]]]
A wireless access point (WAP) connects a group of wireless devices to an adjacent wired LAN. An access point resembles a [[Ethernet hub|network hub]], relaying [[data (computing)|data]] 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 ===
[[File:Wireless network interface controller Gigabyte GC-WB867D-I - front and back - 2018-05-15.jpg|thumb|Wireless network interface controller Gigabyte GC-WB867D-I]]
Wireless adapters allow devices to connect to a wireless network. These adapters connect to devices using various external or internal interconnects such as mini PCIe ([[mPCIe]], [[M.2]]), USB, [[ExpressCard]] and previously PCI, Cardbus, and [[PC Card]]. As of 2010, most newer laptop computers come equipped with built-in internal adapters.
=== Router ===
[[Wireless router]]s integrate a Wireless Access Point, Ethernet [[Network switch|switch]], and internal router firmware application that provides [[Internet Protocol|IP]] [[routing]], [[Network address translation|NAT]], and [[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]], 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]] 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]] and iOS.<ref>{{cite web|url=https://www.apple.com/airportextreme/features/utility.html|title=Apple.com Airport Utility Product Page|publisher=Apple, Inc.|access-date=14 June 2011|url-status=live|archive-url=https://web.archive.org/web/20110608183330/http://www.apple.com/airportextreme/features/utility.html|archive-date=8 June 2011}}</ref>
=== Bridge ===
Wireless [[network bridge]]s can act to connect two networks to form a single network at the [[OSI model#Layer 2: Data link layer|data-link layer]] over Wi-Fi. The main standard is the [[wireless distribution system]] (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 electronics|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 repeater]]s 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 ===
[[File:Ezurio wism2 small.jpg|thumb|Embedded serial-to-Wi-Fi module]]
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]] and are low-power, battery-operated embedded systems. Several Wi-Fi manufacturers design chips and modules for embedded Wi-Fi, such as GainSpan.<ref>{{cite web
|url=http://www.gainspan.com/technology/technology_overview.php
|title=GainSpan low-power, embedded Wi-Fi
|publisher=www.gainspan.com
|access-date=17 June 2017
|archive-url=https://web.archive.org/web/20100630050952/http://www.gainspan.com/technology/technology_overview.php
|archive-date=30 June 2010
|url-status=dead
}}</ref>
Increasingly in the last few years (particularly {{As of| 2007 | lc=on}}), 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.<ref>{{cite web
|url = http://edageek.com/2008/04/18/embedded-wifi-radio/
|title = Quatech Rolls Out Airborne Embedded 802.11 Radio for M2M Market
|access-date = 29 April 2008
|url-status = live
|archive-url = https://web.archive.org/web/20080428103306/http://edageek.com/2008/04/18/embedded-wifi-radio/
|archive-date = 28 April 2008
}}</ref> 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.<ref>{{cite web
|url = http://wifiscan.fr/research/article_19742.htm
|title = CIE article on embedded Wi-Fi for M2M applications
|access-date = 28 November 2014
|url-status = dead
|archive-url = https://web.archive.org/web/20150418040305/http://wifiscan.fr/research/article_19742.htm
|archive-date = 18 April 2015
}}</ref>
These Wi-Fi modules are designed by [[OEM]]s so that implementers need only minimal Wi-Fi knowledge to provide Wi-Fi connectivity for their products.
In June 2014, [[Texas Instruments]] 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.<ref>{{Cite web|url=https://www.macinstallations.com/wifi-connectivity-explained/|title=Wifi Connectivity Explained {{!}} MAC Installations & Consulting|language=en-US|access-date=9 February 2020|archive-date=5 May 2020|archive-url=https://web.archive.org/web/20200505091852/https://www.macinstallations.com/wifi-connectivity-explained/|url-status=live}}</ref>
== Security ==
{{Main|Wireless security}}
The main issue with wireless [[network security]] 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 (computing)|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.<ref>{{cite web|url=http://networkbits.net/wireless-printing/80211-g-pros-cons-of-a-wireless-network-in-a-business-environment/|title=802.11 X Wireless Network in a Business Environment – Pros and Cons.|last=Jensen|first=Joe|date=26 October 2007|website=Networkbits|archive-url=https://web.archive.org/web/20080305075900/http://networkbits.net/wireless-printing/80211-g-pros-cons-of-a-wireless-network-in-a-business-environment/|archive-date=5 March 2008|url-status=usurped|access-date=8 April 2008}}</ref><ref>{{cite news|url=http://www.app.com/article/20130701/NJNEWS/307010010/Free-Wi-Fi-User-beware-Open-connections-Internet-full-security-dangers|title=Free Wi-Fi? User beware: Open connections to Internet are full of security dangers, hackers, ID thieves|last=Higgs|first=Larry|date=1 July 2013|work=[[Asbury Park Press]]|archive-url=https://archive.today/20130702002841/http://www.app.com/article/20130701/NJNEWS/307010010/Free-Wi-Fi-User-beware-Open-connections-Internet-full-security-dangers|archive-date=2 July 2013|url-status=dead}}</ref><ref>{{Cite news|url=https://www.bbc.com/news/technology-26762198|title=Data-stealing Snoopy drone unveiled at Black Hat|last=Gittleson|first=Kim|date=28 March 2014|work=[[BBC News]]|access-date=29 March 2014|archive-url=https://web.archive.org/web/20140330062159/http://www.bbc.co.uk/news/technology-26762198|archive-date=30 March 2014|url-status=live}}</ref>
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.<ref>{{cite web
|url = http://cr.yp.to/djbdns/forgery.html
|title = DNS forgery
|first = Daniel J.
|last = Bernstein
|author-link = Daniel J. Bernstein
|year = 2002
|access-date = 24 March 2010
|quote = An attacker with access to your network can easily forge responses to your computer's DNS requests.
|url-status = live
|archive-url = https://web.archive.org/web/20090727073417/http://cr.yp.to/djbdns/forgery.html
|archive-date = 27 July 2009
}}</ref>
=== 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,<ref>
{{cite web
|url = http://www.cs.wright.edu/~pmateti/InternetSecurity/Lectures/WirelessHacks/Mateti-WirelessHacks.htm#_Toc77524658
|title = Hacking Techniques in Wireless Networks
|last = Mateti
|first = Prabhaker
|year = 2005
|publisher = [[Wright State University]] Department of Computer Science and Engineering
|___location = Dayton, Ohio
|archive-url = https://web.archive.org/web/20100305180937/http://www.cs.wright.edu/~pmateti/InternetSecurity/Lectures/WirelessHacks/Mateti-WirelessHacks.htm#_Toc77524658
|archive-date = 5 March 2010
|url-status = live
|access-date = 28 February 2010
}}</ref> but determined eavesdroppers may be able to join the network by [[MAC spoofing|spoofing]] an authorized address.
[[Wired Equivalent Privacy]] (WEP) encryption was designed to protect against casual snooping but it is no longer considered secure. Tools such as [[AirSnort]] or [[Aircrack-ng]] can quickly recover WEP encryption keys.<ref>{{cite web|url=http://www.wirelessve.org/entries/show/WVE-2005-0020|title=Wireless Vulnerabilities & Exploits|last1=Hegerle|first1=Blake|last2=snax|date=17 August 2001|publisher=wirelessve.org|archive-url=https://archive.today/20060919203035/http://www.wirelessve.org/entries/show/WVE-2005-0020|archive-date=19 September 2006|url-status=dead|access-date=15 April 2008|last3=Bruestle|first3=Jeremy}}</ref> Because of WEP's weakness the Wi-Fi Alliance approved Wi-Fi Protected Access (WPA) which uses [[Temporal Key Integrity Protocol|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]] using [[Advanced Encryption Standard]] was introduced in 2004 and is supported by most new Wi-Fi devices. WPA2 is fully compatible with WPA.<ref name="wpa2-mandatory">{{cite web|url=http://www.wi-fi.org/news_articles.php?f=media_news&news_id=16|title=WPA2 Security Now Mandatory for Wi-Fi CERTIFIED Products|date=13 March 2006|work=[[Wi-Fi Alliance]]|archive-url=https://web.archive.org/web/20110807093143/http://www.wi-fi.org/news_articles.php?f=media_news&news_id=16|archive-date=7 August 2011|url-status=dead}}</ref> In 2017, a flaw in the WPA2 protocol was discovered, allowing a key replay attack, known as [[KRACK]].<ref>{{cite web|url=https://www.krackattacks.com/|title=Key Reinstallation Attacks: Breaking WPA2 by forcing nonce reuse|last=Vanhoef|first=Mathy|date=2017|archive-url=https://web.archive.org/web/20171022022042/https://www.krackattacks.com/|archive-date=22 October 2017|url-status=live|access-date=21 October 2017}}</ref><ref>{{cite web|url=https://arstechnica.com/information-technology/2017/10/severe-flaw-in-wpa2-protocol-leaves-wi-fi-traffic-open-to-eavesdropping/|title=Serious flaw in WPA2 protocol lets attackers intercept passwords and much more|last=Goodin|first=Dan|date=16 October 2017|website=[[Ars Technica]]|archive-url=https://web.archive.org/web/20171021121658/https://arstechnica.com/information-technology/2017/10/severe-flaw-in-wpa2-protocol-leaves-wi-fi-traffic-open-to-eavesdropping/|archive-date=21 October 2017|url-status=live|access-date=21 October 2017}}</ref>
[[File:QR code Wi-Fi.svg|thumb|upright=0.63|A [[QR code]] to automate a Wi-Fi connection using ''WIFI:S:Wikipedia;T:WPA;P:Password1!;;'']]
A flaw in a feature added to Wi-Fi in 2007, called [[Wi-Fi Protected Setup]] (WPS), let WPA and WPA2 security be bypassed. The only remedy {{as of|2011|lc=on}} was to turn off Wi-Fi Protected Setup,<ref>{{cite web |url=http://www.kb.cert.org/vuls/id/723755 |title=CERT/CC Vulnerability Note VU#723755 |access-date=1 January 2012 |url-status=live |archive-url=https://web.archive.org/web/20120103152902/http://www.kb.cert.org/vuls/id/723755 |archive-date=3 January 2012 }} [[US CERT]] Vulnerability Note VU#723755</ref> which is not always possible.
[[Virtual private network]]s can be used to improve the confidentiality of data carried through Wi-Fi networks, especially public Wi-Fi networks.<ref>{{Cite web|url=https://www.consumer.ftc.gov/articles/0014-tips-using-public-wi-fi-networks#protect|title=Tips for Using Public Wi-Fi Networks|author=Federal Trade Commission|date=March 2014|website=Federal Trade Commission – Consumer Information|access-date=8 August 2019|archive-date=9 August 2019|archive-url=https://web.archive.org/web/20190809122844/https://www.consumer.ftc.gov/articles/0014-tips-using-public-wi-fi-networks#protect|url-status=live}}</ref>
A [[URI]] 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]]s, for instance, to join networks without having to manually enter the data.<ref>{{cite web|title=Share your Wi-Fi SSID & Password using a QR Code|url=http://www.technostarry.com/share-wi-fi-details-using-qr-code/|date=19 July 2015|access-date=28 July 2021|archive-date=12 January 2023|archive-url=https://web.archive.org/web/20230112193217/http://www.technostarry.com/share-wi-fi-details-using-qr-code/|url-status=live}}</ref> A [[MeCard (QR code)|MeCard]]-like format is supported by Android and iOS 11+.<ref>{{cite web |title=zxing documentation: barcode contents |url=https://github.com/zxing/zxing/wiki/Barcode-Contents |website=GitHub |publisher=zxing |language=en |access-date=28 July 2021 |archive-date=15 February 2016 |archive-url=https://web.archive.org/web/20160215201205/https://github.com/zxing/zxing/wiki/Barcode-Contents |url-status=live }}</ref>
* Common format: <code>WIFI:S:<SSID>;T:<WEP|WPA|blank>;P:<PASSWORD>;H:<true|false|blank>;</code>
* Sample <code>WIFI:S:MySSID;T:WPA;P:MyPassW0rd;;</code>
=== Data security risks ===
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]], 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]] (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]], or [[Hypertext Transfer Protocol]] over [[Transport Layer Security]] ([[HTTPS]]).
The older wireless-[[encryption]] standard, Wired Equivalent Privacy (WEP), has been [[Fluhrer, Mantin, and Shamir attack|shown]] easily breakable even when correctly configured. Wi-Fi Protected Access (WPA) encryption, which became available in devices in 2003, aimed to solve this problem. Wi-Fi Protected Access 2 (WPA2) ratified in 2004 is considered secure, provided a strong [[passphrase]] is used. The 2003 version of WPA has not been considered secure since it was superseded by WPA2 in 2004.
In 2018, [[WPA3]] was announced as a replacement for WPA2, increasing security;<ref>{{cite web|url=https://www.techspot.com/news/72656-wpa3-protocol-make-public-wi-fi-hotspots-lot.html|title=WPA3 protocol will make public Wi-Fi hotspots a lot more secure|last=Thubron|first=Rob|date=9 January 2018|website=Techspot|archive-url=https://web.archive.org/web/20181116023123/https://www.techspot.com/news/72656-wpa3-protocol-make-public-wi-fi-hotspots-lot.html|archive-date=16 November 2018|url-status=live}}</ref> it rolled out on 26 June.<ref>{{Cite web|url=https://www.theverge.com/circuitbreaker/2018/6/26/17501594/wpa3-wifi-security-certification|title=Wi-Fi security is starting to get its biggest upgrade in over a decade|last=Kastrenakes|first=Jacob|date=26 June 2018|website=[[The Verge]]|archive-url=https://web.archive.org/web/20190220012909/https://www.theverge.com/circuitbreaker/2018/6/26/17501594/wpa3-wifi-security-certification|archive-date=20 February 2019|url-status=live|access-date=26 June 2018}}</ref>
=== Piggybacking ===
{{Main|Piggybacking (Internet access)}}
{{Further|Legality of piggybacking}}
{{Further|Wi-Fi Protected Setup#Physical security issues}}
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]], providing open access points for anyone within range to use was encouraged{{By whom|date=March 2010}} to cultivate [[wireless community network]]s,<ref>{{cite web|title=NoCat's goal is to bring you Infinite Bandwidth Everywhere for Free|url=http://nocat.net/|url-status=dead|archive-url=https://web.archive.org/web/20111022034826/http://nocat.net/|archive-date=22 October 2011|access-date=14 October 2011|website=NoCat.net}}</ref> 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]]. 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]]. These activities do not result in sanctions in most jurisdictions; however, legislation and [[case law]] differ considerably across the world. A proposal to leave [[graffiti]] describing available services was called [[warchalking]].<ref>{{cite web|url=http://www.blackbeltjones.com/warchalking/warchalking0_9.pdf|title=Let's Warchalk|last=Jones|first=Matt|date=24 June 2002|archive-url=https://web.archive.org/web/20080705034313/http://www.blackbeltjones.com/warchalking/warchalking0_9.pdf|archive-date=5 July 2008|url-status=dead|access-date=9 October 2008}}</ref>
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]] and [[Zeroconf]]) this could lead wireless users to send sensitive data to the wrong middle-man when seeking a destination (see [[man-in-the-middle attack]]). For example, a user could inadvertently use an unsecured network to log into a [[website]], thereby making the login credentials available to anyone listening, if the website uses an insecure protocol such as plain [[HTTP]] without [[Transport Layer Security|TLS]].
On an unsecured access point, an unauthorized user can obtain security information (factory preset passphrase 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 or unlawful activities.
== Societal aspects ==
{{See also|Internet #Social Impact}}
Wireless Internet access has become much more embedded in society. It has thus changed how the society functions in a number of ways.
=== Influence on developing countries ===
{{See also|Long-range Wi-Fi}}
{{As of|2017}} over half the world did not have access to the Internet,<ref name=":1">{{Cite journal|last=Decker|first=Kris De|date=6 June 2017|title=Comment bâtir un internet low tech|url=http://journals.openedition.org/tc/8489|journal=Techniques & Culture. Revue semestrielle d'anthropologie des techniques|language=fr|issue=67|pages=216–235|doi=10.4000/tc.8489|s2cid=165080615|issn=0248-6016|access-date=8 May 2020|archive-date=13 July 2020|archive-url=https://web.archive.org/web/20200713111307/https://journals.openedition.org/tc/8489|url-status=live}}</ref> prominently rural areas in developing nations. Technology that has been implemented in more developed nations is often costly and energy inefficient. This has led to developing nations using more low-tech networks, frequently implementing renewable power sources that can solely be maintained through [[solar power]], creating a network that is resistant to disruptions such as power outages. For instance, in 2007, a {{convert|450|km|mi|adj=on}} network between Cabo Pantoja and [[Iquitos]] in [[Peru]] was erected in which all equipment is powered only by [[solar panel]]s.<ref name=":1" /> 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 latter example, it connects the central hospital in Iquitos to 15 medical outposts which are intended for remote diagnosis.<ref name=":1" />
=== Work habits ===
Access to Wi-Fi in public spaces such as cafés 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),<ref name=":2">{{Cite journal|last=Forlano|first=Laura|date=8 October 2009|title=WiFi Geographies: When Code Meets Place|journal=The Information Society|volume=25|issue=5|pages=344–352|doi=10.1080/01972240903213076|s2cid=29969555 |issn=0197-2243}}</ref> other factors influence the choice of specific [[Hotspot (Wi-Fi)|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 (Wi-Fi)|hotspot]].<ref name=":2" />
=== Housing ===
The Internet has become an integral part of living. {{As of|2016}}, 81.9% of American households have Internet access.<ref>{{Cite web|title=Digest of Education Statistics, 2017|url=https://nces.ed.gov/programs/digest/d17/tables/dt17_702.60.asp|website=nces.ed.gov|language=EN|access-date=8 May 2020|archive-date=14 May 2020|archive-url=https://web.archive.org/web/20200514043300/https://nces.ed.gov/programs/digest/d17/tables/dt17_702.60.asp|url-status=live}}</ref> Additionally, 89% of American households with broadband connect via wireless technologies.<ref>{{Cite web|title=Wi-Fi: How Broadband Households Experience the Internet {{!}} NCTA – The Internet & Television Association|url=http://www.ncta.com/whats-new/wi-fi-how-broadband-households-experience-the-internet|website=www.ncta.com|date=6 April 2018 |language=en|access-date=8 May 2020|archive-date=12 May 2020|archive-url=https://web.archive.org/web/20200512044128/https://www.ncta.com/whats-new/wi-fi-how-broadband-households-experience-the-internet|url-status=live}}</ref> 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 signal.<ref name=":2" />
== Health concerns ==
{{Further|Wireless device radiation and health}}
The [[World Health Organization]] (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.<ref>{{cite web
|url =https://www.who.int/mediacentre/factsheets/fs304/en/
|title = Electromagnetic fields and public health – Base stations and wireless technologies
|date = 2006
|publisher = [[World Health Organization]]
|archive-url = https://web.archive.org/web/20160522225458/http://www.who.int/mediacentre/factsheets/fs304/en/
|archive-date = 22 May 2016
|url-status = dead
|access-date = 28 May 2016
}}</ref> Although the WHO's [[International Agency for Research on Cancer]] (IARC) later classified radio-frequency [[electromagnetic field]]s (EMFs) as "possibly carcinogenic to humans ([[List of IARC Group 2B carcinogens|Group 2B]])"<ref>
{{cite web
|url = https://www.iarc.fr/wp-content/uploads/2018/07/pr208_E.pdf
|title = IARC Classifies Radiofrequency Electromagnetic Fields as Possibly Carcinogenic to Humans
|date = 31 May 2011
|publisher = [[International Agency for Research on Cancer]]
|archive-url = https://web.archive.org/web/20120404203349/http://www.iarc.fr/en/media-centre/pr/2011/pdfs/pr208_E.pdf
|archive-date = 4 April 2012
|url-status = live
|access-date = 28 May 2016
}}</ref> (a category used when "a causal association is considered credible, but when chance, bias or confounding cannot be ruled out with reasonable confidence"),<ref>
{{cite web
|url =https://www.who.int/mediacentre/factsheets/fs193/en
|title = Electromagnetic Fields and Public Health: Mobile Phones
|date = October 2014
|access-date = 28 May 2016
|publisher = [[World Health Organization]]
|url-status = dead
|archive-url = https://web.archive.org/web/20160525183100/http://www.who.int/mediacentre/factsheets/fs193/en/
|archive-date = 25 May 2016
}}</ref> this classification was based on risks associated with wireless phone use rather than Wi-Fi networks.{{citation needed|date=June 2025}}
The United Kingdom's [[Health Protection Agency]] 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".<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/technology/6677051.stm|title=Q&A: Wi-fi health concerns|date=21 May 2007|work=[[BBC News]]|access-date=28 May 2016|archive-url=https://web.archive.org/web/20160421152005/http://news.bbc.co.uk/2/hi/technology/6677051.stm|archive-date=21 April 2016|url-status=live}}</ref>
A review of studies involving 725 people who claimed [[electromagnetic hypersensitivity]], "...suggests that 'electromagnetic hypersensitivity' is unrelated to the presence of an EMF, although more research into this phenomenon is required."<ref>{{cite journal|last1=Rubin|first1=G.|last2=Das Munshi|first2=Jayati|last3=Wessely|first3=Simon|date=1 March 2005|title=Electromagnetic Hypersensitivity: A Systematic Review of Provocation Studies|journal=[[Psychosomatic Medicine (journal)|Psychosomatic Medicine]]|volume=67|issue=2|pages=224–232|citeseerx=10.1.1.543.1328|doi=10.1097/01.psy.0000155664.13300.64|pmid=15784787|s2cid=13826364 }}</ref>
== Alternatives ==
Several other wireless technologies provide alternatives to Wi-Fi for different use cases:
* [[Bluetooth Low Energy]], a low-power variant of Bluetooth
* [[Bluetooth]], a short-distance network
* [[Cellular network]]s, used by smartphones
* [[LoRa]], for long range wireless with low data rate
* [[NearLink]], a short-range wireless technology standard
* [[WiMAX]], for providing long range wireless internet connectivity
* [[Zigbee]], a low-power, low data rate, short-distance communication protocol
Some alternatives are "no new wires", re-using existing cable:
* [[G.hn]], which uses existing home wiring, such as phone and [[power line communication|power lines]]
Several ''wired'' technologies for computer networking, which provide viable alternatives to Wi-Fi:
* [[Ethernet over twisted pair]]
== See also ==
{{cols|colwidth=23em}}
* [[Gi-Fi]]{{snd}}a term used by some trade press to refer to faster versions of the IEEE 802.11 standards
* [[HiperLAN]]
* [[High-speed multimedia radio]]
* [[Indoor positioning system]]
* [[Li-Fi]]
* [[List of WLAN channels]]
* [[Operating system Wi-Fi support]]
* [[Passive Wi-Fi]]
* [[Power-line communication]]
* [[San Francisco Digital Inclusion Strategy]]
* [[WLAN Authentication and Privacy Infrastructure|WAPI]]
* [[WiGig]]
* [[Wireless Broadband Alliance]]
* [[Wi-Fi Direct]]
{{colend}}
== Explanatory notes ==
{{Notelist}}
== References ==
{{Reflist|refs=
<ref name="generational">{{cite web |url=https://www.wi-fi.org/file/generational-wi-fi-user-guide |title=Generational Wi-Fi® User Guide |website=[[Wi-Fi Alliance|www.wi{{nbh}}fi.org]] |format=PDF |date=October 2018 |access-date=16 March 2021 |archive-date=30 January 2022 |archive-url=https://web.archive.org/web/20220130074844/https://www.wi-fi.org/downloads-public/Generational_Wi-Fi_User_Guide_20181003.pdf/35678 |url-status=live }}</ref>
<ref name="global-forecast">{{Cite web |date=1 July 2020 |title=Global Wi-Fi Enabled Devices Shipment Forecast, 2020 – 2024 |url=https://www.researchandmarkets.com/reports/5135535/global-wi-fi-enabled-devices-shipment-forecast |access-date=23 November 2020 |website=Research and Markets |archive-date=15 March 2021 |archive-url=https://web.archive.org/web/20210315203540/https://www.researchandmarkets.com/reports/5135535/global-wi-fi-enabled-devices-shipment-forecast |url-status=live }}</ref>
<ref name="scienceabc">{{cite web |url=https://www.scienceabc.com/innovation/do-microwaves-interfere-with-wifi-signals.html |title=Do Microwaves Interfere With WiFi Signals? |date=17 January 2018 |access-date=16 August 2022 |archive-date=16 August 2022 |archive-url=https://web.archive.org/web/20220816204740/https://www.scienceabc.com/innovation/do-microwaves-interfere-with-wifi-signals.html |url-status=live }}</ref>
<ref name="birth">{{Cite web|author=Claus Hetting|title=How a 1998 meeting with Steve Jobs gave birth to Wi-Fi|url=https://wifinowglobal.com/news-and-blog/how-a-meeting-with-steve-jobs-in-1998-gave-birth-to-wi-fi/|access-date=27 May 2021|date=19 August 2018|website=Wi-Fi NOW Global|language=en-US|archive-date=15 December 2020|archive-url=https://web.archive.org/web/20201215231732/https://wifinowglobal.com/news-and-blog/how-a-meeting-with-steve-jobs-in-1998-gave-birth-to-wi-fi/|url-status=live}}</ref>
<ref name="csirowifi">{{Cite news|url=https://www.canberratimes.com.au/national/act/csiro-wifi-invention-to-feature-in-upcoming-exhibition-at-national-museum-of-australia-20160803-gqjyuv.html|title=CSIRO Wi-Fi invention to feature in upcoming exhibition at National Museum of Australia|last=Sibthorpe|first=Clare|date=4 August 2016|newspaper=[[The Canberra Times]]|access-date=4 August 2016|archive-url=https://web.archive.org/web/20160809200721/http://www.canberratimes.com.au/act-news/csiro-wifi-invention-to-feature-in-upcoming-exhibition-at-national-museum-of-australia-20160803-gqjyuv.html|archive-date=9 August 2016|url-status=live}}</ref>
<ref name="boing">{{cite web|url=https://boingboing.net/2005/11/08/wifi-isnt-short-for.html|title=WiFi isn't short for "Wireless Fidelity"|last=Doctorow|first=Cory|author-link=Cory Doctorow|date=8 November 2005|website=[[Boing Boing]]|archive-url=https://web.archive.org/web/20121221132049/http://boingboing.net/2005/11/08/wifi-isnt-short-for.html|archive-date=21 December 2012|url-status=live|access-date=21 December 2012}}</ref>
<ref name="wifi_debunked">{{cite web|url=http://www.wi-fiplanet.com/columns/article.php/3674591|title='Wireless Fidelity' Debunked|last=Graychase|first=Naomi|date=27 April 2007|website=Wi-Fi Planet|archive-url=https://web.archive.org/web/20070928040415/http://www.wi-fiplanet.com/columns/article.php/3674591|archive-date=28 September 2007|url-status=dead|access-date=31 August 2007}}</ref>
}}
== Further reading ==
* {{cite book |author=The WNDW Authors |title=Wireless Networking in the Developing World |editor-last=Butler |editor-first=Jane |year=2013 |isbn=978-1-4840-3935-9|title-link=:File:Wireless Networking in the Developing World (WNDW) Third Edition.pdf |publisher=CreateSpace Independent Publishing Platform |edition=Third}}
{{Internet access}}
{{IEEE standards|state=uncollapsed}}
{{Wireless video}}
{{Telecommunications}}
[[Category:Wi-Fi| ]]
[[Category:Australian inventions]]
[[Category:Telecommunications-related introductions in 1997]]
[[Category:Networking standards]]
[[Category:Wireless communication systems]]
[[Category:Dutch inventions]]
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