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{{Short description|Wireless network standard}}
{{redirect-distinguish|IEEE 802.11x|IEEE 802.1X}}
{{Use Oxford spelling|date=November 2019}}
{{Use dmy dates|date=November 2019}}

[[File:Linksys-Wireless-G-Router.jpg|thumb|This [[Linksys WRT54G series|Linksys WRT54GS]], a combined router and Wi‑Fi access point, operates using the 802.11g standard in the 2.4&nbsp;GHz [[ISM band]] using [[Data signaling rate|signalling rates]] up to 54&nbsp;Mbit/s.]]
[[Image:Wireless network.jpg|thumb|IEEE 802.11 Wi-fi networks are the most widely used wireless networks in the world, connecting devices like [[laptop]]s ''(left)'' to the internet through a wireless router ''(right)'']]

'''IEEE 802.11''' is part of the [[IEEE 802]] set of [[local area network]] (LAN) [[technical standard]]s, and specifies the set of [[medium access control]] (MAC) and [[physical layer]] (PHY) protocols for implementing [[wireless local area network]] (WLAN) computer communication. The standard and amendments provide the basis for wireless network products using the [[Wi-Fi]] brand and are the world's most widely used wireless computer networking standards. IEEE 802.11 is used in most home and office networks to allow laptops, printers, smartphones, and other devices to communicate with each other and access the [[Internet]] without connecting wires. IEEE 802.11 is also a basis for vehicle-based communication networks with [[IEEE 802.11p]].

The standards are created and maintained by the [[Institute of Electrical and Electronics Engineers]] (IEEE) LAN/[[Metropolitan area network|MAN]] Standards Committee (IEEE 802). The base version of the standard was released in 1997 and has had subsequent amendments. While each amendment is officially revoked when it is incorporated in the latest version of the standard, the corporate world tends to market to the revisions because they concisely denote the capabilities of their products. As a result, in the marketplace, each revision tends to become its own standard. '''802.11x''' is a shorthand for "any version of 802.11", to avoid confusion with "802.11" used specifically for [[IEEE 802.11 (legacy mode)|the original 1997 version]].

IEEE 802.11 uses various frequencies including, but not limited to, 2.4&nbsp;GHz, 5&nbsp;GHz, 6&nbsp;GHz, and 60&nbsp;GHz frequency bands. Although IEEE 802.11 specifications list channels that might be used, the allowed [[radio frequency]] spectrum availability varies significantly by regulatory domain.

The protocols are typically used in conjunction with [[IEEE 802.2]], and are designed to interwork seamlessly with [[Ethernet]], and are very often used to carry [[Internet Protocol]] traffic.

{{Wi-Fi Generations}}

==General description==
The 802.11 family consists of a series of [[half-duplex]] over-the-air [[modulation]] techniques that use the same basic protocol. The 802.11 protocol family employs [[carrier-sense multiple access with collision avoidance]] (CSMA/CA) whereby equipment listens to a channel for other users (including non 802.11 users) before transmitting each frame (some use the term "packet", which may be ambiguous: "frame" is more technically correct).

802.11-1997 was the first wireless networking standard in the family, but [[802.11b]] was the first widely accepted one, followed by [[802.11a]], [[802.11g]], [[802.11n]], [[802.11ac]], and [[802.11ax]]. Other standards in the family (c–f, h, j) are service amendments that are used to extend the current scope of the existing standard, which amendments may also include corrections to a previous specification.<ref name="IEEE-SA Standards Board Operations Manual">{{cite web |work=IEEE-SA Standards Board Operations Manual |publisher=IEEE-SA |title=Clause 8 - Publication |url=https://standards.ieee.org/about/policies/opman/sect8/ |access-date=2024-08-24 |url-status=live |archive-url=https://web.archive.org/web/20240531142635/https://standards.ieee.org/about/policies/opman/sect8/ |archive-date=2024-05-31 }}</ref>

802.11b and 802.11g use the 2.4-[[GHz]] [[ISM band]], operating in the United States under [[Part 15]] of the U.S. [[Federal Communications Commission]] Rules and Regulations. 802.11n can also use that 2.4-GHz band. Because of this choice of frequency band, 802.11b/g/n equipment may occasionally suffer [[Electromagnetic interference at 2.4 GHz|interference in the 2.4-GHz band]] from [[microwave oven]]s, [[cordless telephone]]s, and [[Bluetooth]] devices. 802.11b and 802.11g control their interference and susceptibility to interference by using [[direct-sequence spread spectrum]] (DSSS) and [[orthogonal frequency-division multiplexing]] (OFDM) signaling methods, respectively.

802.11a uses the [[U-NII|5&nbsp;GHz U-NII band]] which, for much of the world, offers at least 23 non-overlapping, 20-MHz-wide channels. This is an advantage over the 2.4-GHz, ISM-frequency band, which offers only three non-overlapping, 20-MHz-wide channels where other adjacent channels overlap (see: [[list of WLAN channels]]). Better or worse performance with higher or lower frequencies (channels) may be realized, depending on the environment. 802.11n and 802.11ax can use either the 2.4&nbsp;GHz or 5&nbsp;GHz band; 802.11ac uses only the 5&nbsp;GHz band.

The segment of the [[radio frequency]] spectrum used by 802.11 varies between countries. In the US, 802.11a and 802.11g devices may be operated without a license, as allowed in Part 15 of the FCC Rules and Regulations. Frequencies used by channels one through six of 802.11b and 802.11g fall within the 2.4&nbsp;GHz [[amateur radio]] band. Licensed amateur radio operators may operate 802.11b/g devices under [[Part 97]] of the FCC Rules and Regulations, allowing increased power output but not commercial content or encryption.<ref name="part97">{{cite web |title=ARRLWeb: Part 97 - Amateur Radio Service |publisher=American Radio Relay League |url=http://www.arrl.org/FandES/field/regulations/news/part97/ |access-date=2010-09-27 |url-status=live |archive-url=https://web.archive.org/web/20100309001406/http://www.arrl.org/FandES/field/regulations/news/part97/ |archive-date=2010-03-09 }}</ref>

==Generations==
In 2018, the [[Wi-Fi Alliance]] began using a consumer-friendly generation numbering scheme for the publicly used 802.11 protocols. Wi-Fi generations 1–8 use the 802.11b, 802.11a, 802.11g, 802.11n, 802.11ac, 802.11ax, 802.11be and 802.11bn protocols, in that order.<ref>{{Cite web|url=https://www.wi-fi.org/discover-wi-fi/wi-fi-certified-6|title=Wi-Fi CERTIFIED 6 {{!}} Wi-Fi Alliance|website=www.wi-fi.org|access-date=2019-05-02}}</ref><ref>{{Cite web|url=https://www.theverge.com/2018/10/3/17926212/wifi-6-version-numbers-announced|title=Wi-Fi now has version numbers, and Wi-Fi 6 comes out next year|last=Kastrenakes|first=Jacob|date=2018-10-03|website=The Verge|access-date=2019-05-02}}</ref>[[File:Apple Airport Extreme 802.11g card.jpg|thumb|Apple Airport Extreme installed in an iBook G4]]

==History==
802.11 technology has its origins in a 1985 ruling by the U.S. Federal Communications Commission that released the [[ISM band]]<ref name="IEEE-SA Standards Board Operations Manual" /> for unlicensed use.<ref>{{cite book|author1=Wolter Lemstra|author2=Vic Hayes|author-link2=Vic Hayes|author3=John Groenewegen|title=The Innovation Journey of Wi-Fi: The Road To Global Success|publisher=[[Cambridge University Press]]|date=2010|isbn=978-0-521-19971-1}}</ref>

In 1991 [[NCR Corporation]]/[[AT&T Corporation|AT&T]] (now [[Nokia Labs]] and [[LSI Corporation]]) invented a precursor to 802.11 in Nieuwegein, the Netherlands. The inventors initially intended to use the technology for cashier systems. The first wireless products were brought to the market under the name [[WaveLAN]] with raw data rates of 1&nbsp;Mbit/s and 2&nbsp;Mbit/s.

[[Vic Hayes]], who held the chair of IEEE 802.11 for 10 years, and has been called the "father of Wi-Fi", was involved in designing the initial 802.11b and 802.11a standards 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=2011-04-30 |url-status=dead |archive-url=https://web.archive.org/web/20120826164642/http://news.cnet.com/1200-1070-975460.html |archive-date=2012-08-26 }}</ref> He, along with [[Bell Labs]] Engineer Bruce Tuch, approached IEEE to create a standard.<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|last1=Hetting |first1=Claus }}</ref>

In 1999, the [[Wi-Fi Alliance]] was formed as a trade association to hold the [[Wi-Fi]] trademark under which most products are sold.<ref>{{cite web |title= History |website= [[Wi-Fi Alliance]] |url= https://www.wi-fi.org/who-we-are/history |access-date= 24 August 2020}}</ref>

The major commercial breakthrough came with [[Apple Inc.|Apple's]] adoption of Wi-Fi for their iBook series of laptops in 1999. It was the first mass consumer product to offer Wi-Fi network connectivity, which was then branded by Apple as AirPort.<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}}</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|author=Peter H. Lewis|newspaper=The New York Times|date=25 November 1999}}</ref><ref>{{cite web|url=https://wifinowevents.com/news-and-blog/how-a-meeting-with-steve-jobs-in-1998-gave-birth-to-wi-fi/|title=How a meeting with Steve Jobs in 1998 gave birth to Wi-Fi|author=Claus Hetting|date=19 August 2018|website=Wi-Fi Now|access-date=21 August 2018|archive-date=21 August 2018|archive-url=https://web.archive.org/web/20180821061611/https://wifinowevents.com/news-and-blog/how-a-meeting-with-steve-jobs-in-1998-gave-birth-to-wi-fi/|url-status=dead}}</ref> One year later IBM followed with its ThinkPad 1300 series in 2000.<ref>{{cite web|url=https://thinkstories.com/innovate-die-thinkpad-cracked-code-wireless-world/?linkId=49947536|title=Innovate or die: How ThinkPad cracked the code to the wireless world|access-date=2018-08-24|archive-url=https://web.archive.org/web/20180825004409/https://thinkstories.com/innovate-die-thinkpad-cracked-code-wireless-world/?linkId=49947536|archive-date=2018-08-25|url-status=dead}}</ref>

==Protocol==
{{802.11 network standards|state=uncollapsed}}

===802.11-1997 (802.11 legacy)===
{{Main|IEEE 802.11 (legacy mode)}}

The original version of the standard IEEE 802.11 was released in 1997 and clarified in 1999, but is now obsolete. It specified two [[net bit rate]]s of 1 or 2 [[megabits per second]] (Mbit/s), plus [[forward error correction]] code. It specified three alternative [[physical layer]] technologies: diffuse [[infrared]] operating at 1&nbsp;Mbit/s; [[frequency-hopping]] spread spectrum operating at 1&nbsp;Mbit/s or 2&nbsp;Mbit/s; and [[direct-sequence]] spread spectrum operating at 1&nbsp;Mbit/s or 2&nbsp;Mbit/s. The latter two radio technologies used [[microwave]] transmission over the [[ISM radio band|Industrial Scientific Medical frequency band]] at 2.4&nbsp;GHz. Some earlier WLAN technologies used lower frequencies, such as the U.S. 900&nbsp;MHz ISM band.

Legacy 802.11 with direct-sequence spread spectrum was rapidly supplanted and popularized by 802.11b.

===802.11a (OFDM waveform)===
{{Main|IEEE 802.11a-1999}}

802.11a, published in 1999, uses the same data link layer protocol and frame format as the original standard, but an [[OFDM]] based air interface (physical layer) was added.

It operates in the 5&nbsp;GHz band with a maximum net data rate of 54&nbsp;Mbit/s, plus error correction code, which yields realistic net achievable throughput in the mid-20&nbsp;Mbit/s.<ref>{{cite web |url=http://www.oreillynet.com/wireless/2003/08/08/wireless_throughput.html |title=Wireless throughput |access-date=2011-09-29 |url-status=dead |archive-url=https://web.archive.org/web/20111103014005/http://www.oreillynet.com/wireless/2003/08/08/wireless_throughput.html |archive-date=2011-11-03 }}</ref> It has seen widespread worldwide implementation, particularly within the corporate workspace.

Since the 2.4&nbsp;GHz band is heavily used to the point of being crowded, using the relatively unused 5&nbsp;GHz band gives 802.11a a significant advantage. However, this high [[Center frequency|carrier frequency]] also brings a disadvantage: the effective overall range of 802.11a is less than that of 802.11b/g. In theory, 802.11a signals are absorbed more readily by walls and other solid objects in their path due to their smaller wavelength, and, as a result, cannot penetrate as far as those of 802.11b. In practice, 802.11b typically has a higher range at low speeds (802.11b will reduce speed to 5.5&nbsp;Mbit/s or even 1&nbsp;Mbit/s at low signal strengths). 802.11a also suffers from interference,<ref name="ACIisharmfull">{{Cite journal| last1 = Angelakis  | first1 = V.| last2 = Papadakis | first2 = S.| last3 = Siris | first3 = V.A.| last4 = Traganitis | first4 = A.| title = Adjacent channel interference in 802.11a is harmful: Testbed validation of a simple quantification model| journal = Communications Magazine| volume = 49| issue = 3| pages = 160–166| publisher = IEEE| date = March 2011| issn = 0163-6804| doi = 10.1109/MCOM.2011.5723815| s2cid = 1128416}}</ref> but locally there may be fewer signals to interfere with, resulting in less interference and better throughput.

===802.11b===
{{Main|IEEE 802.11b-1999}}

The 802.11b standard has a maximum raw data rate of 11&nbsp;Mbit/s (Megabits per second) and uses the same media access method defined in the original standard. 802.11b products appeared on the market in early 2000, since 802.11b is a direct extension of the modulation technique defined in the original standard. The dramatic increase in throughput of 802.11b (compared to the original standard) along with simultaneous substantial price reductions led to the rapid acceptance of 802.11b as the definitive wireless LAN technology.

Devices using 802.11b experience interference from other products operating in the 2.4&nbsp;GHz band. Devices operating in the 2.4&nbsp;GHz range include microwave ovens, Bluetooth devices, baby monitors, cordless telephones, and some amateur radio equipment. As unlicensed intentional radiators in this [[ISM band]], they must not interfere with and must tolerate interference from primary or secondary allocations (users) of this band, such as amateur radio.

===802.11g===
{{Main|IEEE 802.11g-2003}}

In June 2003, a third modulation standard was ratified: 802.11g. This works in the 2.4&nbsp;GHz band (like 802.11b), but uses the same [[OFDM]] based transmission scheme as 802.11a. It operates at a maximum physical layer bit rate of 54&nbsp;Mbit/s exclusive of forward error correction codes, or about 22&nbsp;Mbit/s average throughput.<ref name="wndw-pdf">{{cite book|title=Wireless Networking in the Developing World: A practical guide to planning and building low-cost telecommunications infrastructure|publisher=Hacker Friendly LLC|edition=2nd|page=425|year=2007|url=http://wndw.net/pdf/wndw2-en/wndw2-ebook.pdf|url-status=dead|archive-url=https://web.archive.org/web/20081006075431/http://www.wndw.net/pdf/wndw2-en/wndw2-ebook.pdf|archive-date=6 October 2008|access-date=13 March 2009}} page 14</ref> 802.11g hardware is fully backward compatible with 802.11b hardware, and therefore is encumbered with legacy issues that reduce throughput by ~21% when compared to 802.11a.{{citation needed|date=February 2023}}

The then-proposed 802.11g standard was rapidly adopted in the market starting in January 2003, well before ratification, due to the desire for higher data rates as well as reductions in manufacturing costs. {{Citation needed|date=April 2021}} By summer 2003, most dual-band 802.11a/b products became dual-band/tri-mode, supporting a and b/g in a single mobile [[adapter card]] or access point. Details of making b and g work well together occupied much of the lingering technical process; in an 802.11g network, however, the activity of an 802.11b participant will reduce the data rate of the overall 802.11g network.

Like 802.11b, 802.11g devices also suffer interference from other products operating in the 2.4&nbsp;GHz band, for example, wireless keyboards.

===802.11-2007===
In 2003, task group TGma was authorized to "roll up" many of the amendments to the 1999 version of the 802.11 standard. REVma or 802.11ma, as it was called, created a single document that merged 8 amendments ([[802.11a]], [[IEEE 802.11b|b]], [[IEEE 802.11d|d]], [[IEEE 802.11e|e]], [[IEEE 802.11g|g]], [[IEEE 802.11h|h]], [[IEEE 802.11i|i]], [[IEEE 802.11j|j]]) with the base standard. Upon approval on 8 March 2007, 802.11REVma was renamed to the then-current base standard '''IEEE 802.11-2007'''.<ref name=802.11-2007>IEEE 802.11-2007</ref>

===802.11n===
{{Main|IEEE 802.11n-2009}}

802.11n is an amendment that improves upon the previous 802.11 standards; its first draft of certification was published in 2006. The 802.11n standard was retroactively labelled as '''Wi-Fi 4''' by the Wi-Fi Alliance.<ref name="Wi-Fi Alliance® introduces Wi-Fi 6">{{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}}</ref><ref name="Shankland">{{Cite web |url=https://www.cnet.com/news/wi-fi-alliance-simplifying-802-11-wireless-network-tech-names/ |title=Here come Wi-Fi 4, 5 and 6 in plan to simplify 802.11 networking names - The Wi-Fi Alliance wants to make wireless networks easier to understand and recognize |last=Shankland |first=Stephen |date=2018-10-03 |website=[[CNET]] |access-date=2020-02-13}}</ref> The standard added support for [[multiple-input multiple-output]] antennas (MIMO). 802.11n operates on both the 2.4&nbsp;GHz and the 5&nbsp;GHz bands. Support for 5&nbsp;GHz bands is optional. Its net data rate ranges from 54&nbsp;Mbit/s to 600&nbsp;Mbit/s. The IEEE has approved the amendment, and it was published in October 2009.<ref name=80211nPR>{{cite web |url=http://standards.ieee.org/announcements/ieee802.11n_2009amendment_ratified.html |title=IEEE-SA - News & Events |website=[[IEEE Standards Association]] |access-date=2012-05-24 |url-status=dead |archive-url=https://web.archive.org/web/20100726095111/http://standards.ieee.org/announcements/ieee802.11n_2009amendment_ratified.html |archive-date=2010-07-26 }}</ref><ref name=802.11-2009>{{cite book |publisher=[[IEEE-SA]] |date=29 October 2009 |doi=10.1109/IEEESTD.2009.5307322 |isbn=978-0-7381-6046-7 |title=IEEE Standard for Information technology-- Local and metropolitan area networks-- Specific requirements-- Part 11: Wireless LAN Medium Access Control (MAC)and Physical Layer (PHY) Specifications Amendment 5: Enhancements for Higher Throughput }}</ref> 

Prior to the final ratification, enterprises were already migrating to 802.11n networks based on the Wi-Fi Alliance's certification of products conforming to a 2007 draft of the 802.11n proposal. Early Intel WiFi cards were not compatible with the final standard. Many rival access points and cards also did not support 5&nbsp;GHz at all.{{cn|date=December 2024|reason=Both Intel and 5 GHz limitations need support}}

===802.11-2012===
In May 2007, task group TGmb was authorized to "roll up" many of the amendments to the 2007 version of the 802.11 standard.<ref>{{cite web|url=https://grouper.ieee.org/groups/802/11/Reports/tgm_update.htm|title=IEEE P802 - Task Group M Status|access-date=24 August 2020}}</ref> REVmb or 802.11mb, as it was called, created a single document that merged ten amendments ([[802.11k]], [[IEEE 802.11r|r]], [[IEEE 802.11y|y]], [[IEEE 802.11n|n]], [[IEEE 802.11w|w]], [[IEEE 802.11p|p]], [[IEEE 802.11z-2010|z]], [[IEEE 802.11v|v]], [[IEEE 802.11u|u]], [[IEEE 802.11s|s]]) with the 2007 base standard. In addition much cleanup was done, including a reordering of many of the clauses.<ref name=802.11-2012>{{cite web|url=http://blogs.aerohive.com/blog/the-wi-fi-security-blog/why-did-80211-2012-renumber-clauses|title=Why did 802.11-2012 renumber clauses?|author=Matthew Gast|publisher=[[Aerohive Networks]]|access-date=2012-11-17|url-status=dead|archive-url=https://web.archive.org/web/20121111042610/http://blogs.aerohive.com/blog/the-wi-fi-security-blog/why-did-80211-2012-renumber-clauses|archive-date=2012-11-11}}</ref> Upon publication on 29 March 2012, the new standard was referred to as '''IEEE 802.11-2012'''.

===802.11ac===
{{Main|IEEE 802.11ac}}
IEEE 802.11ac-2013 is an amendment to IEEE 802.11, published in December 2013, that builds on 802.11n.<ref name="80211ac-approved">{{cite web |url=http://standards.ieee.org/news/2014/ieee_802_11ac_ballot.html |title=New IEEE 802.11ac™ Specification Driven by Evolving Market Need for Higher, Multi-User Throughput in Wireless LANs |last=Kelly |first=Vivian |publisher=IEEE |date=2014-01-07 |access-date=2014-01-11 |url-status=dead |archive-url=https://web.archive.org/web/20140112011626/http://standards.ieee.org/news/2014/ieee_802_11ac_ballot.html |archive-date=2014-01-12 }}</ref> The 802.11ac standard was retroactively labelled as '''Wi-Fi 5''' by the Wi-Fi Alliance.<ref name="Wi-Fi Alliance® introduces Wi-Fi 6"/><ref name="Shankland"/> Changes compared to 802.11n include wider channels (80 or 160&nbsp;MHz versus 40&nbsp;MHz) in the 5&nbsp;GHz band, more spatial streams (up to eight versus four), higher-order modulation (up to 256-[[QAM]] vs. 64-QAM), and the addition of [[Multi-user MIMO]] (MU-MIMO). The Wi-Fi Alliance separated the introduction of ac wireless products into two phases ("waves"), named "Wave 1" and "Wave 2".<ref>{{cite web|url=https://www.xirrus.com/pdf/Wave2_Whitepaper.pdf|title=802.11AC WAVE 2 A XIRRUS WHITE PAPER}}</ref><ref>{{cite web|url=https://www.networkcomputing.com/wireless/80211ac-wi-fi-part-2-wave-1-and-wave-2-products/1614338859|title=802.11ac Wi-Fi Part 2: Wave 1 and Wave 2 Products}}</ref> From mid-2013, the alliance started certifying Wave 1 802.11ac products shipped by manufacturers, based on the IEEE 802.11ac Draft 3.0 (the IEEE standard was not finalized until later that year).<ref>{{cite web|url=https://cdn2.hubspot.net/hubfs/282305/Old/New%20Belden.com%20-%20Master%20Resources/blog-pdfs/white_paper_c11-713103.pdf|title=802.11ac: The Fifth Generation of Wi-Fi Technical White Paper|date=March 2014|website=Cisco|access-date=13 February 2020|archive-date=18 April 2023|archive-url=https://web.archive.org/web/20230418202027/https://cdn2.hubspot.net/hubfs/282305/Old/New%20Belden.com%20-%20Master%20Resources/blog-pdfs/white_paper_c11-713103.pdf|url-status=dead}}</ref> In 2016 Wi-Fi Alliance introduced the Wave 2 certification, to provide higher bandwidth and capacity than Wave 1 products. Wave 2 products include additional features like MU-MIMO, 160&nbsp;MHz channel width support, support for more 5&nbsp;GHz channels, and four spatial streams (with four antennas; compared to three in Wave 1 and 802.11n, and eight in IEEE's 802.11ax specification).<ref>{{cite web|url=https://www.rcrwireless.com/20160629/network-infrastructure/wi-fi/wi-fi-alliance-launches-802-11ac-wave-2-certification-tag6|title=Wi-Fi Alliance launches 802.11ac Wave 2 certification|website=RCR Wireless|date=29 June 2016}}</ref><ref name=techrepublic>{{cite web|url=https://www.techrepublic.com/article/6-things-you-need-to-know-about-802-11ac-wave-2/ |title=6 things you need to know about 802.11ac Wave 2 |website=techrepublic.com |date=2016-07-13 |access-date=2018-07-26}}</ref>

===802.11ad===
{{Update|section|date=November 2013}} <!-- ad: need updating with more relevant info. -->
{{Main|IEEE 802.11ad}}
IEEE 802.11ad is an amendment that defines a new [[physical layer]] for 802.11 networks to operate in the 60&nbsp;GHz [[millimeter wave]] spectrum. This frequency band has significantly different propagation characteristics than the 2.4&nbsp;GHz and 5&nbsp;GHz bands where Wi-Fi networks operate. Products implementing the [[802.11ad]] standard are being brought to market under the [[WiGig]] brand name, with a  certification program developed by the Wi-Fi Alliance.<ref>{{cite press release | url=https://www.wi-fi.org/news-events/newsroom/wi-fi-certified-wigig-brings-multi-gigabit-performance-to-wi-fi-devices | title=Wi-Fi CERTIFIED WiGig™ brings multi-gigabit performance to Wi-Fi® devices | publisher=Wi-Fi Alliance | date=October 24, 2016}}</ref> The peak transmission rate of 802.11ad is 7&nbsp;Gbit/s.<ref>{{cite web|url=http://standards.ieee.org/getieee802/download/802.11ad-2012.pdf|title=IEEE Standard Association - IEEE Get Program|website=IEEE Standards Association|access-date=8 January 2016|url-status=dead|archive-url=https://web.archive.org/web/20151224035601/http://standards.ieee.org/getieee802/download/802.11ad-2012.pdf|archive-date=24 December 2015}}</ref>

IEEE 802.11ad is a protocol used for very high data rates (about 8&nbsp;Gbit/s) and for short range communication (about 1–10 meters).<ref>{{cite web|url=https://devopedia.org/ieee-802-11ad|title=IEEE 802.11ad|website=Devopedia|access-date=5 January 2019|date=8 March 2018}}</ref>

TP-Link announced the world's first 802.11ad router in January 2016.<ref>{{Cite web|title = TP-Link unveils world's first 802.11ad WiGig router|url = https://arstechnica.com/gadgets/2016/01/tp-link-unveils-worlds-first-802-11ad-wigig-router/|website = Ars Technica|date = 8 January 2016|access-date = 2016-01-16|url-status = live|archive-url = https://web.archive.org/web/20160116165329/http://arstechnica.com/gadgets/2016/01/tp-link-unveils-worlds-first-802-11ad-wigig-router/|archive-date = 2016-01-16}}</ref>

The WiGig standard is not too well known, although it was announced in 2009 and added to the IEEE 802.11 family in December 2012.

===802.11af===
{{Main|IEEE 802.11af}}

IEEE 802.11af, also referred to as "White-Fi" and "[[Super Wi-Fi]]",<ref name="80211afLekomtcev">{{cite magazine|title=Comparison of 802.11af and 802.22 standards – physical layer and cognitive functionality|url=http://www.elektrorevue.cz/file.php?id=200000861-9a19f9b13f|date=June 2012|access-date=2013-12-29|last1=Lekomtcev|first1=Demain|last2=Maršálek|first2=Roman|magazine=Elektrorevue|volume=3|issue=2|issn=1213-1539}}</ref> is an amendment, approved in February 2014, that allows WLAN operation in TV [[White spaces (radio)|white space spectrum]] in the [[VHF]] and [[UHF]] bands between 54 and 790&nbsp;MHz.<ref name="80211timeline"/><ref name="80211afflores">{{cite web|title=IEEE 802.11af: A Standard for TV White Space Spectrum Sharing|url=http://networks.rice.edu/papers/FINAL_article_80211af.pdf|publisher=IEEE|last1=Flores|first1=Adriana B.|last2=Guerra|first2=Ryan E.|last3=Knightly|first3=Edward W.|last4=Ecclesine|first4=Peter|last5=Pandey|first5=Santosh|date=October 2013|access-date=2013-12-29|url-status=dead|archive-url=https://web.archive.org/web/20131230232954/http://networks.rice.edu/papers/FINAL_article_80211af.pdf|archive-date=2013-12-30}}</ref> It uses [[cognitive radio]] technology to transmit on unused TV channels, with the standard taking measures to limit interference for primary users, such as analog TV, digital TV, and wireless microphones.<ref name="80211afflores"/> Access points and stations determine their position using a satellite positioning system such as [[GPS]], and use the Internet to query a [[TV White Space Database|geolocation database (GDB)]] provided by a regional regulatory agency to discover what frequency channels are available for use at a given time and position.<ref name="80211afflores"/> The physical layer uses OFDM and is based on 802.11ac.<ref name="80211afLim">{{cite web|url=http://edu.tta.or.kr/sub3/down.php?No=139&file=1-4_TVWS_Regulation_and_Standardization_%C0%D3%B5%BF%B1%B9.pdf|first=Dongguk|last=Lim|title=TVWS Regulation and Standardization (IEEE 802.11af)|date=2013-05-23|access-date=2013-12-29|archive-url=https://web.archive.org/web/20131231001459/http://edu.tta.or.kr/sub3/down.php?No=139&file=1-4_TVWS_Regulation_and_Standardization_%C0%D3%B5%BF%B1%B9.pdf|archive-date=2013-12-31|url-status=dead}}</ref> The propagation path loss as well as the attenuation by materials such as brick and concrete is lower in the UHF and VHF bands than in the 2.4&nbsp;GHz and 5&nbsp;GHz bands, which increases the possible range.<ref name="80211afflores"/> The frequency channels are 6 to 8&nbsp;MHz wide, depending on the regulatory domain.<ref name="80211afflores"/> Up to four channels may be bonded in either one or two contiguous blocks.<ref name="80211afflores"/> MIMO operation is possible with up to four streams used for either [[space–time block code]] (STBC) or multi-user (MU) operation.<ref name="80211afflores"/> The achievable data rate per spatial stream is 26.7&nbsp;Mbit/s for 6 and 7&nbsp;MHz channels, and 35.6&nbsp;Mbit/s for 8&nbsp;MHz channels.<ref name="80211afDraft"/> With four spatial streams and four bonded channels, the maximum data rate is 426.7&nbsp;Mbit/s for 6 and 7&nbsp;MHz channels and 568.9&nbsp;Mbit/s for 8&nbsp;MHz channels.<ref name="80211afDraft"/>

===802.11-2016===
IEEE 802.11-2016 which was known as IEEE 802.11 REVmc,<ref name=":0">{{cite web|url=https://www.wirelesstrainingsolutions.com/802-11-2016/|title=802.11-2016|date=12 August 2017|website=Wireless Training & Solutions|access-date=5 January 2019}}</ref> is a revision based on IEEE 802.11-2012, incorporating 5 amendments ([[IEEE 802.11ae|11ae]], [[IEEE 802.11aa|11aa]], [[11ad]], [[11ac]], [[11af]]). In addition, existing MAC and PHY functions have been enhanced and obsolete features were removed or marked for removal. Some clauses and annexes have been renumbered.<ref name=":1">{{cite web |url=https://standards.ieee.org/findstds/standard/802.11-2016.html |title=IEEE 802.11-2016 |access-date=2017-03-25 |url-status=dead |archive-url=https://web.archive.org/web/20170308153100/http://standards.ieee.org/findstds/standard/802.11-2016.html |archive-date=2017-03-08 }}</ref>

===802.11ah===
{{Main|IEEE 802.11ah}}

IEEE 802.11ah, published in 2017,<ref>{{cite book|doi=10.1109/IEEESTD.2017.7920364 |isbn=978-1-5044-3911-4 |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 Amendment 2: Sub 1 GHZ License Exempt Operation }}</ref> defines a WLAN system operating at sub-1&nbsp;GHz license-exempt bands. Due to the favorable propagation characteristics of the low-frequency spectra, 802.11ah can provide improved transmission range compared with the conventional 802.11 WLANs operating in the 2.4&nbsp;GHz and 5&nbsp;GHz&nbsp;bands. 802.11ah can be used for various purposes including large-scale sensor networks,<ref name="80211ah-daily-wireless">{{cite web |url=http://www.dailywireless.org/2013/08/30/802-11ah-wifi-standard-for-900mhz/ |last=Churchill |first=Sam |title=802.11ah: WiFi Standard for 900MHz |date=2013-08-30 |access-date=2014-02-11 |website=DailyWireless |url-status=dead |archive-url=https://web.archive.org/web/20140210073727/http://www.dailywireless.org/2013/08/30/802-11ah-wifi-standard-for-900mhz/ |archive-date=10 February 2014 }}</ref> extended-range hotspots, and outdoor Wi-Fi for cellular WAN carrier traffic offloading, whereas the available bandwidth is relatively narrow. The protocol intends consumption to be competitive with low-power [[Bluetooth]], at a much wider range.<ref name="theverge">{{cite web|url=https://www.theverge.com/2016/1/4/10691400/new-wifi-halow-standard-announced-iot-ces-2016|title=There's a new type of Wi-Fi, and it's designed to connect your smart home|date=2016-01-04|website=[[The Verge]]|access-date=2015-01-04|url-status=live|archive-url=https://web.archive.org/web/20160104142935/http://www.theverge.com/2016/1/4/10691400/new-wifi-halow-standard-announced-iot-ces-2016|archive-date=2016-01-04}}</ref>

===802.11ai===
{{Main|IEEE 802.11ai}}

IEEE 802.11ai is an amendment to the 802.11 standard that added new mechanisms for a faster initial link setup time.<ref name="ieee802.org">{{Cite web |url=http://www.ieee802.org/11/Reports/802.11_Timelines.htm |title=IEEE 802.11, The Working Group Setting the Standards for Wireless LANs |access-date=29 June 2017 |url-status=live |archive-url=https://web.archive.org/web/20170701094002/http://www.ieee802.org/11/Reports/802.11_Timelines.htm |archive-date=1 July 2017 }}</ref>

===802.11aj===
IEEE 802.11aj is a derivative of 802.11ad for use in the 45&nbsp;GHz unlicensed spectrum available in some regions of the world (specifically China); it also provides additional capabilities for use in the 60&nbsp;GHz band.<ref name="ieee802.org"/>

Alternatively known as China Millimeter Wave (CMMW).<ref>{{Cite web |last=Mitchell |first=Bradley |date=November 16, 2021 |title=802.11 Standards Explained: 802.11ax, 802.11ac, 802.11b/g/n, 802.11a |url=https://www.lifewire.com/wireless-standards-802-11a-802-11b-g-n-and-802-11ac-816553#toc-80211aj |access-date=April 16, 2023 |website=Livewire}}</ref>

===802.11aq===
IEEE 802.11aq is an amendment to the 802.11 standard that will enable pre-association discovery of services. This extends some of the mechanisms in 802.11u that enabled device discovery to discover further the services running on a device, or provided by a network.<ref name="ieee802.org"/>

=== 802.11-2020 ===
IEEE 802.11-2020, which was known as IEEE 802.11 REVmd,<ref>{{Cite web|title=IEEE 802.11 Working Group Project Timelines | url=https://www.ieee802.org/11/Reports/802.11_Timelines.htm | access-date=2021-04-04 | website=IEEE}}</ref> is a revision based on IEEE 802.11-2016 incorporating 5 amendments ([[11ai]], [[11ah]], [[IEEE 802.11aj|11aj]], [[IEEE 802.11ak|11ak]], [[IEEE 802.11aq|11aq]]). In addition, existing MAC and PHY functions have been enhanced and obsolete features were removed or marked for removal. Some clauses and annexes have been added.<ref>{{Cite web|title=IEEE 802.11-2020 - 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|url=https://standards.ieee.org/ieee/802.11/7028/|access-date=2021-04-04|website=IEEE Standards|archive-date=6 February 2022|archive-url=https://web.archive.org/web/20220206191751/https://standards.ieee.org/ieee/802.11/7028/|url-status=dead}}</ref>

===802.11ax===
{{Main|IEEE 802.11ax}}

IEEE 802.11ax is the successor to 802.11ac, marketed as '''{{nowrap|Wi-Fi 6}}''' (2.4&nbsp;GHz and 5&nbsp;GHz)<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=22 March 2021}}</ref> and {{nowrap|Wi-Fi 6E}} (6&nbsp;GHz)<ref name="6e">{{cite web |url=https://www.wi-fi.org/file/wi-fi-6e-highlights |title=Wi-Fi 6E expands Wi-Fi® into 6 GHz |website=[[Wi-Fi Alliance|www.wi{{nbh}}fi.org]] |format=PDF |date=January 2021 |access-date=22 March 2021}}</ref> by the [[Wi-Fi Alliance]]. It is also known as ''High Efficiency'' {{nowrap|Wi-Fi}}, for the overall improvements to {{nowrap|Wi-Fi 6}} clients in ''dense environments''.<ref name="atutorial" /> For an individual client, the maximum improvement in data rate ([[PHY]] speed) against the predecessor (802.11ac) is only 39%{{efn|802.11ax with '''2402&nbsp;Mbit/s''' (MCS Index 11, 2 spatial streams, 160&nbsp;MHz); versus 802.11ac with '''1733.3&nbsp;Mbit/s''' (MCS Index 9, 2 spatial streams, 160&nbsp;MHz).<ref name="semfio">{{cite web |url=https://www.semfionetworks.com/blog/mcs-table-updated-with-80211ax-data-rates |title=MCS Table (Updated with 802.11ax Data Rates) |website=www.semfionetworks.com |date=11 April 2019 |access-date=22 March 2021}}</ref>}} (for comparison, this improvement was nearly 500%{{efn|802.11ac with '''1733.3&nbsp;Mbit/s''' (MCS Index 9, 2 spatial streams, 160&nbsp;MHz); versus 802.11n with '''300&nbsp;Mbit/s''' (MCS Index 7, 2 spatial streams, 40&nbsp;MHz}}{{efn-lr|This improvement is 1100% if we consider 144.4&nbsp;Mbit/s (MCS Index 15, 2 spatial streams, '''20&nbsp;MHz'''), due to 40&nbsp;MHz mode from 802.11n (at 2.4&nbsp;GHz) having little practical use in most scenarios.<ref name="duckware">{{cite web |url=https://www.duckware.com/tech/wifi-in-the-us.html#wifi6 |title=Understanding Wi-Fi 4/5/6/6E (802.11 n/ac/ax) |website=www.duckware.com |last=Jongerius |first=Jerry |date=25 November 2020 |access-date=22 March 2021}}</ref>{{rp|qt|q="in virtually all circumstances, you will only get 1/2 of the advertised speed (only be able to use a 20&nbsp;MHz channel)!"}}).<ref name="semfio" />}} for the predecessors).{{efn|An [[IEEE]] article considers only a 37% growth for 802.11ax and a 1000% growth for both 802.11ac and 802.11n.<ref name="atutorial" />}} Yet, even with this comparatively minor 39% figure, the goal was to provide ''4 times'' the [[throughput]]-per-area{{efn|Throughput-per-area, as defined by [[IEEE]], is the ratio of the total network throughput to the network area.<ref name="atutorial" />}} of 802.11ac (hence ''High Efficiency''). The motivation behind this goal was the deployment of [[WLAN]] in dense environments such as corporate offices, shopping malls and dense residential apartments.<ref name="atutorial" /> This is achieved by means of a technique called [[OFDMA]], which is basically multiplexing in the [[Frequency-division multiplexing|''frequency domain'']] (as opposed to [[spatial multiplexing|''spatial'' multiplexing]], as in 802.11ac). This is equivalent to [[Cellular network|cellular technology]] applied into {{nowrap|Wi-Fi}}.<ref name="atutorial">{{cite journal |doi=10.1109/COMST.2018.2871099|doi-access=free |title=A Tutorial on IEEE 802.11ax High Efficiency WLANs |year=2019 |last1=Khorov |first1=Evgeny |last2=Kiryanov |first2=Anton |last3=Lyakhov |first3=Andrey |last4=Bianchi |first4=Giuseppe |journal=IEEE Communications Surveys & Tutorials |volume=21 |pages=197–216 }}</ref>{{rp|qt|q="The key feature of 802.11ax is the adoption of an OFDMA approach, an approach widely used in cellular networks, but brand new in Wi-Fi."}}

The IEEE 802.11ax{{nbh}}2021 standard was approved on February 9, 2021.<ref name="ieeefeb">{{cite web |url=https://standards.ieee.org/about/sasb/sba/feb2021/ |title=IEEE SA Standards Board Approvals - 09/10 February 2021 |website=[[IEEE]] |date=9 February 2021 |access-date=11 March 2021}}</ref><ref name="ieeeapproval">{{cite web |url=https://standards.ieee.org/ieee/802.11ax/7180/ |archive-url=https://web.archive.org/web/20210314171855/https://standards.ieee.org/standard/802_11ax-2021.html |url-status=live |archive-date=14 March 2021 |title=IEEE 802.11ax-2021 - IEEE Approved Draft Standard for Information technology&nbsp;[...] |website=[[IEEE|www.ieee.org]] |date=9 February 2021 |access-date=11 March 2021}}</ref>

===802.11ay===
{{Main|IEEE 802.11ay}}
{{Update|section|date=March 2015}} <!-- ay: need updating with more relevant info. -->

IEEE 802.11ay is a standard that is being developed, also called EDMG: Enhanced Directional MultiGigabit PHY. It is an amendment that defines a new [[physical layer]] for 802.11 networks to operate in the 60&nbsp;GHz [[millimeter wave]] spectrum. It will be an extension of the existing 11ad, aimed to extend the throughput, range, and use-cases. The main use-cases include indoor operation and short-range communications due to atmospheric oxygen absorption and inability to penetrate walls. The peak transmission rate of 802.11ay is 40&nbsp;Gbit/s.<ref>{{cite web|title=P802.11ay|url=https://development.standards.ieee.org/get-file/P802.11ay.pdf?t=85389900003|publisher=IEEE|access-date=19 August 2015|page=1|quote=This amendment defines standardized modifications to both the IEEE 802.11 physical layers (PHY) and the IEEE 802.11 medium access control layer (MAC) that enables at least one mode of operation capable of supporting a maximum throughput of at least 20 gigabits per second (measured at the MAC data service access point), while maintaining or improving the power efficiency per station.|url-status=dead|archive-url=https://web.archive.org/web/20161015163345/https://development.standards.ieee.org/get-file/P802.11ay.pdf?t=85389900003|archive-date=15 October 2016}}</ref> The main extensions include: channel bonding (2, 3 and 4), [[MIMO]] (up to 4 streams) and higher modulation schemes. The expected range is 300–500 m.<ref>{{Cite web|url=https://www.youtube.com/watch?v=BzPdEnHVc1Y|title = 60GHZ What you need to know about 802 11ad and 802 11ay &#124; Jason Hintersteiner &#124; WLPC Phoenix 2019|website = [[YouTube]]| date=28 February 2019 }}</ref>

===802.11ba===

IEEE 802.11ba Wake-up Radio (WUR) Operation is an amendment to the IEEE 802.11 standard that enables energy-efficient operation for data reception without increasing latency.<ref>{{Cite web|url=https://www.ieee802.org/11/Reports/tgba_update.htm|title=IEEE P802.11 Task Group BA - Wake-up Radio Operation|website=www.ieee802.org|access-date=2020-08-12}}</ref> The target active power consumption to receive a WUR packet is less than 1 milliwatt and supports data rates of 62.5&nbsp;kbit/s and 250&nbsp;kbit/s. The WUR PHY uses MC-OOK (multicarrier [[On–off keying|OOK]]) to achieve extremely low power consumption.<ref>{{Cite journal| last1 = Liu  | first1 = R.| last2 = Beevi K.T. | first2 = A.| last3 =Dorrance| first3=R.| first4=D.|last4= Dasalukunte| first5= V.|last5= Kristem|first6= M. A. |last6=Santana Lopez|first7= A. W. |last7=Min|first8= S.|last8=Azizi|first9= M.|last9=Park|first10= B. R.|last10=Carlton | title = An 802.11ba-Based Wake-Up Radio Receiver With Wi-Fi Transceiver Integration| journal = Journal of Solid-State Circuits| volume = 55| issue = 5| pages = 1151–1164| publisher = IEEE| date = May 2020|doi=10.1109/JSSC.2019.2957651| bibcode = 2020IJSSC..55.1151L| s2cid = 214179940}}</ref>

===802.11bb===
[[IEEE 802.11bb]] is a networking protocol standard in the IEEE 802.11 set of protocols that uses infrared light for communications.<ref>{{Cite web |first=Mark|last= Tyson |date=2023-07-12 |title=100x Faster Than Wi-Fi: Li-Fi, Light-Based Networking Standard Released |url=https://www.tomshardware.com/news/li-fi-standard-released |access-date=2023-07-13 |website=Tom's Hardware |language=en}}</ref>

===802.11be===
{{Main|IEEE 802.11be}}

IEEE 802.11be Extremely High Throughput (EHT) is the potential next amendment to the 802.11 IEEE standard,<ref>{{Cite web|url=http://www.ieee802.org/11/Reports/ehtsg_update.htm|title=IEEE P802.11 EXTREMELY HIGH THROUGHPUT Study Group|website=www.ieee802.org|access-date=2019-05-20}}</ref> and will likely be designated as '''Wi-Fi 7'''.<ref name="cnet-wifi7">{{Cite web |last=Shankland |first=Stephen |date=2019-09-03 |title=Wi-Fi 6 is barely here, but Wi-Fi 7 is already on the way - With improvements to Wi-Fi 6 and its successor, Qualcomm is working to boost speeds and overcome congestion on wireless networks. |url=https://www.cnet.com/news/wi-fi-6-is-barely-here-but-wi-fi-7-is-already-on-the-way/ |access-date=2020-08-20 |website=[[CNET]]}}</ref><ref name="ieee-wifi7">{{Cite journal |last1=Khorov |first1=Evgeny |first2=Ilya |last2=Levitsky |first3=Ian F. |last3=Akyildiz |date=2020-05-08 |title=Current Status and Directions of IEEE 802.11be, the Future Wi-Fi 7 |journal=[[IEEE Access]]|volume=8 |pages=88664–88688 |doi=10.1109/ACCESS.2020.2993448 |bibcode=2020IEEEA...888664K |s2cid=218834597 |doi-access=free }}</ref> It will build upon 802.11ax, focusing on WLAN indoor and outdoor operation with stationary and pedestrian speeds in the 2.4&nbsp;GHz, 5&nbsp;GHz, and 6&nbsp;GHz frequency bands.

==Common misunderstandings about achievable throughput==
[[File:Throughputenvelope80211g.png|thumb|upright=1.5|Graphical representation of Wi‑Fi application-specific ([[User Datagram Protocol|UDP]]) performance envelope in the 2.4&nbsp;GHz band with 802.11g. 1 Mbps = 1 [[Mbit/s]].]]

Across all variations of 802.11, maximum achievable throughputs are given either based on measurements under ideal conditions or in the layer-2 data rates. However, this does not apply to typical deployments in which data is being transferred between two endpoints, of which at least one is typically connected to a wired infrastructure and the other endpoint is connected to an infrastructure via a wireless link.

[[File:ThroughputEnvelope11n.png|thumb|upright=1.5|Graphical representation of Wi‑Fi application-specific ([[User Datagram Protocol|UDP]]) performance envelope in the 2.4&nbsp;GHz band with 802.11n, using a 40&nbsp;MHz channel]]

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 application's packet size determines the speed of the data transfer. This means applications that use small packets (e.g., VoIP) create dataflows with high-overhead traffic (i.e., a 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, of course, 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|first1=Markus|last1=Tauber|first2=Saleem|last2=Bhatti|first3=Yi|last3=Yu|url=https://www.researchgate.net/publication/241631429|conference=IEEE/IFIP NOMS 2012: IEEE/IFIP Network Operations and Management Symposium|location=Maui, HI, USA|doi=10.1109/NOMS.2012.6211930|access-date=2014-08-11|url-status=live|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|archive-date=2014-08-13}}</ref><ref>{{cite conference|title=Application Level Energy and Performance Measurements in a Wireless LAN|first1=Markus|last1=Tauber|first2=Saleem|last2=Bhatti|first3=Yi|last3=Yu|url=https://www.researchgate.net/publication/224264522|conference=The 2011 IEEE/ACM International Conference on Green Computing and Communications|location=Sichuan, China|doi=10.1109/GreenCom.2011.26|access-date=2014-08-11|url-status=live|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|archive-date=2014-08-13}}</ref>

The same references apply to the attached graphs that show measurements of [[User Datagram Protocol|UDP]] throughput. Each represents an average (UDP) throughput (please note that the error bars are there but barely visible due to the small variation) of 25 measurements. Each is with a specific packet size (small or large) and with a specific data rate (10&nbsp;kbit/s – 100&nbsp;Mbit/s). Markers for traffic profiles of common applications are included as well. These figures assume there are no packet errors, which, if occurring, will lower the transmission rate further.

==<span id="ChannelsAndFreqs"></span>Channels and frequencies==
{{See also|List of WLAN channels}}

802.11b, 802.11g, and 802.11n-2.4 utilize the {{nowrap|2.400–2.500 GHz}} spectrum, one of the [[ISM band]]s. 802.11a, 802.11n, and 802.11ac use the more heavily regulated {{nowrap|4.915–5.825 GHz}} band. These are commonly referred to as the "2.4&nbsp;GHz and 5&nbsp;GHz bands" in most sales literature. Each spectrum is sub-divided into ''channels'' with a center frequency and bandwidth, analogous to how radio and TV broadcast bands are sub-divided.

The 2.4&nbsp;GHz band is divided into 14 channels spaced 5&nbsp;MHz apart, beginning with channel&nbsp;1, which is centered on 2.412&nbsp;GHz. The latter channels have additional restrictions or are unavailable for use in some regulatory domains.

[[File:2.4 GHz Wi-Fi channels (802.11b,g WLAN).svg|thumb|center|upright=3.25|Graphical representation of [[Wi-Fi]] channels in the 2.4&nbsp;GHz band]]

The channel numbering of the {{nowrap|5.725–5.875 GHz}} spectrum is less intuitive due to the differences in regulations between countries. These are discussed in greater detail on the [[List of WLAN channels#5GHz|list of WLAN channels]].

===Channel spacing within the 2.4&nbsp;GHz band===
In addition to specifying the channel center frequency, 802.11 also specifies (in Clause 17) a [[spectral mask]] defining the permitted power distribution across each channel. The mask requires the signal to be [[Attenuation|attenuated]] a minimum of 20&nbsp;[[decibel|dB]] from its peak amplitude at ±11&nbsp;MHz from the center frequency, the point at which a channel is effectively 22&nbsp;MHz wide. One consequence is that stations can use only every fourth or fifth channel without overlap.

Availability of channels is regulated by country, constrained in part by how each country [[Frequency allocation|allocates radio spectrum]] to various services. At one extreme, Japan permits the use of all 14 channels for 802.11b, and {{nowrap|1–13}} for 802.11g/n-2.4. Other countries such as Spain initially allowed only channels 10 and 11, and France allowed only 10, 11, 12, and 13; however, Europe now allow channels 1 through 13.<ref name="CNAF">{{cite web|title=Cuadro nacional de Atribución de Frecuencias CNAF|publisher=Secretaría de Estado de Telecomunicaciones |url=http://www.mityc.es/Telecomunicaciones/Secciones/Espectro/cnaf |access-date=2008-03-05 |archive-url=https://web.archive.org/web/20080213092618/http://www.mityc.es/Telecomunicaciones/Secciones/Espectro/cnaf <!-- Bot retrieved archive --> |archive-date = 2008-02-13}}</ref><ref name="ART">{{cite web|title=Evolution du régime d'autorisation pour les RLAN|publisher=French Telecommunications Regulation Authority (ART)|url=http://www.arcep.fr/uploads/tx_gspublication/evol-rlan-250703.pdf|access-date=2008-10-26|url-status=dead|archive-url=https://web.archive.org/web/20061209172043/http://www.arcep.fr/uploads/tx_gspublication/evol-rlan-250703.pdf|archive-date=9 December 2006}}</ref> North America and some Central and South American countries allow only {{nowrap|1 through 11.}}

[[File:2.4 GHz Wi-Fi channels (802.11g WLAN).svg|thumb|center|upright=3.25|Spectral masks for 802.11g channels {{nowrap|1–14}} in the 2.4&nbsp;GHz band]]

Since the spectral mask defines only power output restrictions up to ±11&nbsp;MHz from the center frequency to be attenuated by −50&nbsp;dBr, it is often assumed that the energy of the channel extends no further than these limits. It is more correct to say that the overlapping signal on any channel should be sufficiently attenuated to interfere with a transmitter on any other channel minimally, given the separation between channels. Due to the [[near–far problem]] a transmitter can impact (desensitize) a receiver on a "non-overlapping" channel, but only if it is close to the victim receiver (within a meter) or operating above allowed power levels. Conversely, a sufficiently distant transmitter on an overlapping channel can have little to no significant effect.

Confusion often arises over the amount of channel separation required between transmitting devices. 802.11b was based on [[direct-sequence spread spectrum]] (DSSS) modulation and utilized a channel bandwidth of 22&nbsp;MHz, resulting in ''three'' "non-overlapping" channels (1, 6, and 11). 802.11g was based on OFDM modulation and utilized a channel bandwidth of 20&nbsp;MHz. This occasionally leads to the belief that ''four'' "non-overlapping" channels (1, 5, 9, and 13) exist under 802.11g. However, this is not the case as per 17.4.6.3 Channel Numbering of operating channels of the IEEE Std 802.11 (2012), which states, "In a multiple cell network topology, overlapping and/or adjacent cells using different channels can operate simultaneously without interference if the distance between the center frequencies is at least 25&nbsp;MHz."<ref>{{cite web|title=Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications|url=http://standards.ieee.org/getieee802/download/802.11-2012.pdf|access-date=2013-12-05|url-status=dead|archive-url=https://web.archive.org/web/20130626000833/http://standards.ieee.org/getieee802/download/802.11-2012.pdf|archive-date=2013-06-26}}</ref>
and section 18.3.9.3 and Figure 18-13.

This does not mean that the technical overlap of the channels recommends the non-use of overlapping channels. The amount of inter-channel interference seen on a configuration using channels 1, 5, 9, and 13 (which is permitted in Europe, but not in North America) is barely different from a three-channel configuration, but with an entire extra channel.<ref>{{cite web|title=Choosing the clearest channels for WiFi... continued|url=https://www.wirelesswaffle.com/index.php?m=02&y=13&entry=entry130212-072406|access-date=2020-08-24}}</ref><ref name="adjacentchannels">{{Cite conference |last1=Garcia Villegas |first1=E. |title=Effect of adjacent-channel interference in IEEE 802.11 WLANs |conference=CrownCom 2007 |publisher=ICST & IEEE |year=2007 |url=https://upcommons.upc.edu/e-prints/bitstream/2117/1234/1/CrownCom07_CReady.pdf |display-authors=etal |url-status=dead |archive-url=https://web.archive.org/web/20110720102658/https://upcommons.upc.edu/e-prints/bitstream/2117/1234/1/CrownCom07_CReady.pdf |archive-date=20 July 2011 |access-date=17 September 2008 }}</ref>

[[File:NonOverlappingChannels2.4GHz802.11-en.svg|thumb|802.11 non-overlapping channels in the 2.4&nbsp;GHz ISM band]]

However, overlap between channels with more narrow spacing (e.g. 1, 4, 7, 11 in North America) may cause unacceptable degradation of signal quality and throughput, particularly when users transmit near the boundaries of AP cells.<ref name="ciscodeployissues">{{cite web |title=Channel Deployment Issues for 2.4&nbsp;GHz 802.11 WLANs |publisher=Cisco Systems, Inc |url=http://www.cisco.com/en/US/docs/wireless/technology/channel/deployment/guide/Channel.html |access-date=2007-02-07 |url-status=dead |archive-url=https://web.archive.org/web/20140209230927/http://www.cisco.com/en/US/docs/wireless/technology/channel/deployment/guide/Channel.html |archive-date=2014-02-09 }}</ref>

===Regulatory domains and legal compliance===
IEEE uses the phrase ''regdomain'' to refer to a legal regulatory region. Different countries define different levels of allowable transmitter power, time that a channel can be occupied, and different available channels.<ref>{{cite web|url=https://standards.ieee.org/standard/802_11-2007.html|archive-url=https://web.archive.org/web/20180915002138/https://standards.ieee.org/standard/802_11-2007.html|url-status=dead|archive-date=15 September 2018|title=IEEE Standard 802.11-2007|page=531}}</ref> Domain codes are specified for the United States, Canada, [[ETSI|ETSI (Europe)]], Spain, France, Japan, and China.

Most [[Wi-Fi|Wi-Fi certified]] devices default to ''regdomain'' 0, which means [[least common denominator]] settings, i.e., the device will not transmit at a power above the allowable power in any nation, nor will it use frequencies that are not permitted in any nation.{{citation needed|date=November 2011}}<!-- is this even possible? No ''regdomain'' 0 behavior shows up in 802.11-2007 that I can find -->

The ''regdomain'' setting is often made difficult or impossible to change so that the end-users do not conflict with local regulatory agencies such as the United States' [[Federal Communications Commission]].{{citation needed|date=January 2021}}

==Layer 2 – Datagrams==
The [[datagram]]s are called ''frames''. Current 802.11 standards specify frame types for use in the transmission of data as well as management and control of wireless links.

Frames are divided into very specific and standardized sections. Each frame consists of a ''MAC header'', ''payload'', and ''[[frame check sequence]]'' (FCS). Some frames do not have payloads.

{| class="wikitable"
|-
! Field
| Frame <br/>control
| Duration, <br/>{{abbr|id.|association id.}}
| Address <br/>1
| Address <br/>2
| Address <br/>3
| Sequence <br/>control
| Address <br/>4
| {{abbr|QoS|Quality of service}} <br/>control
| {{abbr|HT|High throughput}} <br/>control
| Frame <br/>body
| Frame check <br/>sequence
|-
! Length (Bytes)
| 2
| 2
| 6
| 6
| 6
| 0, or 2
| 6
| 0, or 2
| 0, or 4
| {{n/a|''Variable''}}
| 4
|}

The first two bytes of the MAC header form a frame control field specifying the form and function of the frame. This frame control field is subdivided into the following sub-fields:
* Protocol Version: Two bits representing the protocol version. The currently used protocol version is zero. Other values are reserved for future use.
* Type: Two bits identifying the type of WLAN frame. Control, Data, and Management are various frame types defined in IEEE 802.11.
* Subtype: Four bits providing additional discrimination between frames. Type and Subtype are used together to identify the exact frame.
* ToDS and FromDS: Each is one bit in size. They indicate whether a data frame is headed for a distribution system or it is getting out of it. Control and management frames set these values to zero. All the data frames will have one of these bits set.
** ToDS = 0 and FromDS = 0
*** Communication within a [[Service set (802.11 network)|basic service set]] or an [[independent basic service set]] (IBSS) network.
**ToDS = 0 and FromDS = 1
***A frame sent by a station and directed to an AP accessed via the distribution system.
**ToDS = 1 and FromDS = 0
***A frame exiting the distribution system for a station.
**ToDS = 1 and FromDS = 1
***Only kind of frame frame that uses all four MAC addresses in a DATA frame.
***Address 1: access point address exiting from the distribution system.
***Address 2: access point entrance to the distribution system (AP to which the source station is connected).
***Address 3: final station address.
***Address 4: address of the source station.<ref>{{Cite web |date=2010-10-25 |title=802.11 frames : A starter guide to learn wireless sniffer traces |url=https://community.cisco.com/t5/wireless-mobility-knowledge-base/802-11-frames-a-starter-guide-to-learn-wireless-sniffer-traces/ta-p/3110019 |access-date=2023-01-24 |website=community.cisco.com |language=en}}</ref><ref>{{Cite book |last=Gast |first=Matthew S. |title=802.11 wireless networks: the definitive guide; [creating & administering wireless networks; covers 802.11a, g, n & i] |date=2013 |publisher=O'Reilly |isbn=978-0-596-10052-0 |edition=2nd |location=Beijing |chapter=Chapter 4. 802.11 Framing in Detail |chapter-url=https://www.oreilly.com/library/view/80211-wireless-networks/0596100523/ch04.html}}</ref>
* More Fragments: The More Fragments bit is set when a packet is divided into multiple frames for transmission. Every frame except the last frame of a packet will have this bit set.
* Retry: Sometimes frames require retransmission, and for this, there is a Retry bit that is set to one when a frame is resent. This aids in the elimination of duplicate frames.
* Power Management: This bit indicates the power management state of the sender after the completion of a frame exchange. Access points are required to manage the connection and will never set the power-saver bit.
* More Data: The More Data bit is used to buffer frames received in a distributed system. The access point uses this bit to facilitate stations in power-saver mode. It indicates that at least one frame is available and addresses all stations connected.
* Protected Frame: The Protected Frame bit is set to the value of one if the frame body is encrypted by a protection mechanism such as [[Wired Equivalent Privacy]] (WEP), [[Wi-Fi Protected Access]] (WPA), or Wi-Fi Protected Access II (WPA2).
* Order: This bit is set only when the "strict ordering" delivery method is employed. Frames and fragments are not always sent in order as it causes a transmission performance penalty.

The next two bytes are reserved for the Duration ID field, indicating how long the field's transmission will take so other devices know when the channel will be available again. This field can take one of three forms: Duration, Contention-Free Period (CFP), and Association ID (AID).

An 802.11 frame can have up to four address fields. Each field can carry a [[MAC address]]. Address 1 is the receiver, Address 2 is the transmitter, Address 3 is used for filtering purposes by the receiver.{{Dubious|date=December 2015}} Address 4 is only present in data frames transmitted between access points in an [[Extended Service Set]] or between intermediate nodes in a [[mesh network]].

The remaining fields of the header are:
* The Sequence Control field is a two-byte section used to identify message order and eliminate duplicate frames. The first 4 bits are used for the fragmentation number, and the last 12 bits are the sequence number.
* An optional two-byte Quality of Service control field, present in QoS Data frames; it was added with [[802.11e]].

The payload or frame body field is variable in size, from 0 to 2304 bytes plus any overhead from security encapsulation, and contains information from higher layers.

The Frame Check Sequence (FCS) is the last four bytes in the standard 802.11 frame. Often referred to as the Cyclic Redundancy Check (CRC), it allows for integrity checks of retrieved frames. As frames are about to be sent, the FCS is calculated and appended. When a station receives a frame, it can calculate the FCS of the frame and compare it to the one received. If they match, it is assumed that the frame was not distorted during transmission.<ref name="802.11 Technical Section">{{cite web|url=http://wifi.cs.st-andrews.ac.uk/wififrame.html|title=802.11 Technical Section|archive-url=https://web.archive.org/web/20090124151617/http://wifi.cs.st-andrews.ac.uk/wififrame.html|archive-date=2009-01-24|url-status=dead}}</ref>

===Management frames===
Management frames are [[IEEE 802.11w-2009|not always authenticated]], and allow for the maintenance, or discontinuance, of communication. Some common 802.11 subtypes include:
* Authentication frame: 802.11 authentication begins with the [[wireless network interface controller]] (WNIC) sending an authentication frame to the access point containing its identity.
** When open system authentication is being used, the WNIC sends only a single authentication frame, and the access point responds with an authentication frame of its own indicating acceptance or rejection.
** When shared key authentication is being used, the WNIC sends an initial authentication request, and the access point responds with an authentication frame containing challenge text. The WNIC then sends an authentication frame containing the encrypted version of the challenge text to the access point. The access point confirms the text was encrypted with the correct key by decrypting it with its own key. The result of this process determines the WNIC's authentication status.
* Association request frame: Sent from a station, it enables the access point to allocate resources and synchronize. The frame carries information about the WNIC, including supported data rates and the [[SSID]] of the network the station wishes to associate with. If the request is accepted, the access point reserves memory and establishes an association ID for the WNIC.
* Association response frame: Sent from an access point to a station containing the acceptance or rejection to an association request. If it is an acceptance, the frame will contain information such as an association ID and supported data rates.
* [[Beacon frame]]: Sent periodically from an access point to announce its presence and provide the [[SSID]] and other parameters for WNICs within range.
* {{vanchor|Deauthentication frame}}: Sent from a station wishing to terminate connection from another station.
* Disassociation frame: Sent from a station wishing to terminate the connection. It is an elegant way to allow the access point to relinquish memory allocation and remove the WNIC from the association table.
* Probe request frame: Sent from a station when it requires information from another station.
* Probe response frame: Sent from an access point containing capability information, supported data rates, etc., after receiving a probe request frame.
* Reassociation request frame: A WNIC sends a reassociation request when it drops from the currently associated access point range and finds another access point with a stronger signal. The new access point coordinates the forwarding of any information that may still be contained in the buffer of the previous access point.
* Reassociation response frame: Sent from an access point containing the acceptance or rejection to a WNIC reassociation request frame. The frame includes information required for association such as the association ID and supported data rates.
* Action frame: extending management frame to control a certain action. Some of the action categories are Block Ack, Radio Measurement, Fast BSS Transition, etc. These frames are sent by a station when it needs to tell its peer for a certain action to be taken. For example, a station can tell another station to set up a [[block acknowledgement]] by sending an ''ADDBA Request'' action frame. The other station would then respond with an ''ADDBA Response'' action frame.

The body of a management frame consists of frame-subtype-dependent fixed fields followed by a sequence of [[information element]]s (IEs).

The common structure of an IE is as follows:

{| class="wikitable"
|-
! Field
| Type
| Length
| Data
|-
! Length
| 1
| 1
| 1–252
|}

===Control frames===
Control frames facilitate the exchange of data frames between stations. Some common 802.11 control frames include:
* Acknowledgement (ACK) frame: After receiving a data frame, the receiving station will send an ACK frame to the sending station if no errors are found. If the sending station does not receive an ACK frame within a predetermined period of time, the sending station will resend the frame.
* Request to Send (RTS) frame: The [[IEEE 802.11 RTS/CTS|RTS and CTS frames]] provide an optional collision reduction scheme for access points with hidden stations. A station sends an RTS frame as the first step in a two-way handshake required before sending data frames.
* Clear to Send (CTS) frame: A station responds to an RTS frame with a CTS frame. It provides clearance for the requesting station to send a data frame. The CTS provides collision control management by including a time value for which all other stations are to hold off transmission while the requesting station transmits.

===Data frames===
Data frames carry packets from web pages, files, etc. within the body.<ref name="Frame Types">{{cite web|url=http://www.wi-fiplanet.com/tutorials/article.php/1447501|title=Understanding 802.11 Frame Types|access-date=2008-12-14|url-status=dead|archive-url=https://web.archive.org/web/20081125033409/http://www.wi-fiplanet.com/tutorials/article.php/1447501|archive-date=2008-11-25}}</ref> The body begins with an [[IEEE 802.2]] header, with the Destination [[Service Access Point]] (DSAP) specifying the protocol, followed by a [[Subnetwork Access Protocol]] (SNAP) header if the DSAP is hex AA, with the [[organizationally unique identifier]] (OUI) and protocol ID (PID) fields specifying the protocol. If the OUI is all zeroes, the protocol ID field is an [[EtherType]] value.<ref>{{cite web|url=https://scm.info.ucl.ac.be/release/cnp3/Book/0.2/html/lan/lan.html#wireless-networks|archive-url=https://archive.today/20121127171405/https://scm.info.ucl.ac.be/release/cnp3/Book/0.2/html/lan/lan.html%23wireless-networks|archive-date=27 November 2012|url-status=dead|title=Computer Networking : Principles, Protocols and Practice|first=Olivier|last=Bonaventure|access-date=2012-07-09}}</ref> Almost all 802.11 data frames use 802.2 and SNAP headers, and most use an OUI of 00:00:00 and an EtherType value.

Similar to [[TCP congestion control]] on the internet, frame loss is built into the operation of 802.11. To select the correct transmission speed or [[Modulation and Coding Scheme]], a rate control algorithm may test different speeds. The actual packet loss rate of Access points varies widely for different link conditions. There are variations in the loss rate experienced on production Access points, between 10% and 80%, with 30% being a common average.<ref>{{cite conference|author1= D Murray |author2=T Koziniec |author3=M Dixon |author4=K. Lee|title=Measuring the reliability of 802.11 WiFi networks|conference=2015 Internet Technologies and Applications|year=2015|pages=233–238 |doi=10.1109/ITechA.2015.7317401|isbn=978-1-4799-8036-9 |s2cid=14997671 }}</ref> It is important to be aware that the link layer should recover these lost frames. If the sender does not receive an Acknowledgement (ACK) frame, then it will be resent.

==Standards and amendments==
Within the IEEE 802.11 Working Group,<ref name="80211timeline">{{cite web |url=https://grouper.ieee.org/groups/802/11/Reports/802.11_Timelines.htm |access-date=2016-04-20 |date=2016-03-23 |title=Official IEEE 802.11 working group project timelines |url-status=live |archive-url=https://web.archive.org/web/20160407191026/http://grouper.ieee.org/groups/802/11/Reports/802.11_Timelines.htm |archive-date=2016-04-07 }}</ref> the following [[IEEE Standards Association]] Standard and Amendments exist:

<!--Please do not add a standard to this list unless it is an IEEE standard and you have a reference back to IEEE's website. -->
* [[IEEE 802.11-1997]]: The WLAN standard was originally 1&nbsp;Mbit/s and 2&nbsp;Mbit/s, 2.4&nbsp;GHz RF and [[infrared]] (IR) standard (1997), all the others listed below are Amendments to this standard, except for Recommended Practices 802.11F and 802.11T.
* '''[[IEEE 802.11a]]''': 54&nbsp;Mbit/s, 5&nbsp;GHz standard (1999, shipping products in 2001)
* '''[[IEEE 802.11b]]''': 5.5&nbsp;Mbit/s and 11&nbsp;Mbit/s, 2.4&nbsp;GHz standard (1999)
* [[IEEE 802.11c]]: Bridge operation procedures; included in the [[IEEE 802.1D]] standard (2001)
* [[IEEE 802.11d]]: International (country-to-country) roaming extensions (2001)
* [[IEEE 802.11e]]: Enhancements: [[Quality of service|QoS]], including packet bursting (2005)
* [[IEEE 802.11F]]: [[Inter-Access Point Protocol]] (2003) <sub>Withdrawn February 2006</sub>
* '''[[IEEE 802.11g]]''': 54&nbsp;Mbit/s, 2.4&nbsp;GHz standard (backwards compatible with b) (2003)
* [[IEEE 802.11h]]: Spectrum Managed 802.11a (5&nbsp;GHz) for European compatibility (2004)
* [[IEEE 802.11i]]: Enhanced security (2004)
* [[IEEE 802.11j]]: Extensions for Japan (4.9-5.0&nbsp;GHz) (2004)
* IEEE 802.11-2007: A new release of the standard that includes amendments a, b, d, e, g, h, i, and j. (July 2007)
* [[IEEE 802.11k]]: Radio resource measurement enhancements (2008)
* '''[[IEEE 802.11n]]''': Higher Throughput [[WLAN]] at 2.4 and 5&nbsp;GHz; 20 and 40&nbsp;MHz channels; introduces [[MIMO]] to {{nowrap|Wi-Fi}} (September 2009)
* [[IEEE 802.11p]]: WAVE—Wireless Access for the Vehicular Environment (such as ambulances and passenger cars) (July 2010)
* [[IEEE 802.11r]]: Fast BSS transition (FT) (2008)
* [[IEEE 802.11s]]: Mesh Networking, [[Extended Service Set]] (ESS) (July 2011)
* IEEE 802.11T: Wireless Performance Prediction (WPP)—test methods and metrics Recommendation <sub>cancelled</sub>
* [[IEEE 802.11u]]: Improvements related to HotSpots and 3rd-party authorization of clients, e.g., cellular network offload (February 2011)
* [[IEEE 802.11v]]: Wireless [[network management]] (February 2011)
* [[IEEE 802.11w]]: Protected Management Frames (September 2009)
* [[IEEE 802.11y]]: 3650–3700&nbsp;MHz Operation in the U.S. (2008)
* [[IEEE 802.11z]]: Extensions to Direct Link Setup (DLS) (September 2010)
* IEEE 802.11-2012: A new release of the standard that includes amendments k, n, p, r, s, u, v, w, y, and z (March 2012)
* IEEE 802.11aa: Robust streaming of Audio Video Transport Streams (June 2012) - see [[Stream Reservation Protocol]]
* '''[[IEEE 802.11ac]]''': Very High Throughput [[WLAN]] at 5&nbsp;GHz;{{efn|Operation in the 2.4&nbsp;GHz band is specified by [[802.11n]].}} wider channels (80 and 160&nbsp;MHz); [[Multi-user MIMO]] (down-link only)<ref>{{cite web |url=https://arstechnica.com/business/guides/2009/12/wifi-looks-to-1-gigabit-horizon.ars/1 |title=The future of WiFi: gigabit speeds and beyond |website=Ars Technica |last=Fleishman |first=Glenn |date=7 December 2009 |access-date=2009-12-13 |url-status=live |archive-url=https://web.archive.org/web/20091213033437/http://arstechnica.com/business/guides/2009/12/wifi-looks-to-1-gigabit-horizon.ars/1 |archive-date=13 December 2009 }}</ref> (December 2013)
* '''[[IEEE 802.11ad]]''': Very High Throughput 60&nbsp;GHz (December 2012) — see also [[WiGig]]
* IEEE 802.11ae: Prioritization of Management Frames (March 2012)
* [[IEEE 802.11af]]: [[White spaces (radio)|TV Whitespace]] (February 2014)
* IEEE 802.11-2016: A new release of the standard that includes amendments aa, ac, ad, ae, and af (December 2016)
* [[IEEE 802.11ah]]: Sub-1&nbsp;GHz license exempt operation (e.g., sensor network, smart metering) (December 2016)
* [[IEEE 802.11ai]]: Fast Initial Link Setup (December 2016)
* [[IEEE 802.11aj]]: China Millimeter Wave (February 2018)
* IEEE 802.11ak: Transit Links within [[Bridging (networking)|Bridged Networks]] (June 2018)
* IEEE 802.11aq: Pre-association Discovery (July 2018)
* IEEE 802.11-2020: A new release of the standard that includes amendments ah, ai, aj, ak, and aq (December 2020)
* '''[[IEEE 802.11ax]]''': High Efficiency [[WLAN]] at 2.4, 5 and 6&nbsp;GHz;{{efn|6&nbsp;GHz operation only between {{nowrap|'''Wi-Fi 6E'''}} devices.}} introduces [[OFDMA]] to {{nowrap|Wi-Fi}}<ref name="atutorial" /> (February 2021)
* [[IEEE 802.11ay]]: Enhancements for Ultra High Throughput in and around the 60&nbsp;GHz Band (March 2021)
* IEEE 802.11az: Next Generation Positioning (March 2023)
* [[IEEE 802.11ba]]: Wake Up Radio (March 2021)
* [[IEEE 802.11bb]]: Light Communications (November 2023)
* IEEE 802.11bc: Enhanced Broadcast Service (February 2024)
* [[IEEE 802.11bd]]: Enhancements for Next Generation V2X (see also [[IEEE 802.11p]]) (March 2023)

===In process===
* '''[[IEEE 802.11be]]''': ''Extremely High Throughput'' (see also [[IEEE 802.11ax]]) (May 2024)
* IEEE 802.11bf: ''WLAN Sensing''
* IEEE 802.11bh: ''Randomized and Changing MAC Addresses''
* IEEE 802.11bi: ''Enhanced Data Privacy''
* IEEE 802.11bk: ''320 MHz Positioning''
* '''[[IEEE 802.11bn]]''': ''Ultra High Reliability''
* IEEE 802.11bp: ''Ambient Power Communication''
* IEEE 802.11me: 802.11 Accumulated Maintenance Changes
* IEEE 802.11mf: 802.11 Accumulated Maintenance Changes

802.11F and 802.11T are recommended practices rather than standards and are capitalized as such.

802.11m is used for standard maintenance. 802.11ma was completed for 802.11-2007, 802.11mb for 802.11-2012, [[802.11mc]] for 802.11-2016, and 802.11md for 802.11-2020.

===Standard vs. amendment===
Both the terms "standard" and "amendment" are used when referring to the different variants of IEEE standards.<ref>{{cite journal|journal=IEEE Communications Surveys & Tutorials|volume=PP|issue=99|pages=162–183|date=4 December 2014|publisher=IEEE|doi=10.1109/COMST.2014.2377373|title=MU-MIMO MAC Protocols for Wireless Local Area Networks: A Survey|arxiv=1404.1622|bibcode=2014arXiv1404.1622L|last1=Liao|first1=Ruizhi|last2=Bellalta|first2=Boris|last3=Oliver|first3=Miquel|last4=Niu|first4=Zhisheng|s2cid=8462498}}</ref>

As far as the IEEE Standards Association is concerned, there is only one current standard; it is denoted by IEEE 802.11 followed by the date published. IEEE 802.11-2020 is the only version currently in publication, superseding previous releases. The standard is updated by means of amendments. Amendments are created by task groups (TG). Both the task group and their finished document are denoted by 802.11 followed by one or two lower case letters, for example, [[IEEE 802.11a]] or [[IEEE 802.11ax]]. Updating 802.11 is the responsibility of task group m. In order to create a new version, TGm combines the previous version of the standard and all published amendments. TGm also provides clarification and interpretation to industry on published documents. New versions of the '''IEEE 802.11''' were published in 1999, 2007, 2012, 2016, and 2020.<ref>{{cite web|url=https://grouper.ieee.org/groups/802/11/Reports/802.11_Timelines.htm|title=IEEE 802.11, The Working Group Setting the Standards for Wireless LANs|website=IEEE Standards Association Working Group Site & Liaison Index|access-date=8 January 2016|url-status=live|archive-url=https://web.archive.org/web/20160122035132/http://grouper.ieee.org/groups/802/11/Reports/802.11_Timelines.htm|archive-date=22 January 2016}}</ref><ref>{{cite book |publisher=[[IEEE-SA]] |url=https://ieeexplore.ieee.org/document/9442429 |date=19 May 2021 |doi=10.1109/IEEESTD.2021.9442429 |isbn=978-1-5044-7389-7 | 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 Amendment 1: Enhancements for High-Efficiency WLAN }}</ref>

==Nomenclature==
Various terms in 802.11 are used to specify aspects of wireless local-area networking operation and may be unfamiliar to some readers.

For example, ''[[TU (time unit)|time unit]]'' (usually abbreviated ''TU'') is used to indicate a unit of time equal to 1024 [[microsecond]]s. Numerous time constants are defined in terms of TU (rather than the nearly equal millisecond).

Also, the term ''portal'' is used to describe an entity that is similar to an [[IEEE 802.1|802.1H]] bridge. A portal provides access to the WLAN by non-802.11 LAN STAs.

==Security==
{{Update section|date=February 2024|reason=WPA2 is no longer the latest version of WPA}}
In 2001, a group from the [[University of California, Berkeley]] presented a paper describing weaknesses in the [[802.11]] Wired Equivalent Privacy (WEP) security mechanism defined in the original standard; they were followed by [[Fluhrer, Mantin and Shamir attack|Fluhrer, Mantin, and Shamir]]'s paper titled "Weaknesses in the Key Scheduling Algorithm of [[RC4]]". Not long after, Adam Stubblefield and [[AT&T Corporation|AT&T]] publicly announced the first verification of the attack. In the attack, they were able to intercept transmissions and gain unauthorized access to wireless networks.<ref>{{Cite web |title=Security Flaws in 802.11 Data Link Protocols |url=https://people.eecs.berkeley.edu/~daw/papers/wireless-cacm.pdf}}</ref>

The IEEE set up a dedicated task group to create a replacement security solution, 802.11i (previously, this work was handled as part of a broader 802.11e effort to enhance the [[MAC layer]]). The Wi-Fi Alliance announced an interim specification called [[Wi-Fi Protected Access]] (WPA) based on a subset of the then-current IEEE 802.11i draft. These started to appear in products in mid-2003. [[IEEE 802.11i]] (also known as WPA2) itself was ratified in June 2004, and uses the [[Advanced Encryption Standard]] (AES), instead of [[RC4]], which was used in WEP. The modern recommended encryption for the home/consumer space is WPA2 (AES Pre-Shared Key), and for the enterprise space is WPA2 along with a [[RADIUS]] authentication server (or another type of authentication server) and a strong authentication method such as [[EAP-TLS]].{{citation needed|date=May 2020}}

In January 2005, the IEEE set up yet another [[IEEE 802.11w-2009|task group "w"]] to protect management and broadcast frames, which previously were sent unsecured. Its standard was published in 2009.<ref>{{cite web |title= Status of Project IEEE 802.11 Task Group w: Protected Management Frames |author= Jesse Walker, Chair |date= May 2009 |url= https://grouper.ieee.org/groups/802/11/Reports/tgw_update.htm |access-date= 24 August 2020}}</ref>

In December 2011, a security flaw was revealed that affects some wireless routers with a specific implementation of the optional [[Wi-Fi Protected Setup]] (WPS) feature. While WPS is not a part of 802.11, the flaw allows an attacker within the range of the wireless router to recover the WPS PIN and, with it, the router's 802.11i password in a few hours.<ref>{{cite web |url=http://sviehb.files.wordpress.com/2011/12/viehboeck_wps.pdf |website=.braindump – RE and stuff |title=Brute forcing Wi-Fi Protected Setup |date=2011-12-26 |url-status=live |archive-url=https://web.archive.org/web/20120118105726/http://sviehb.files.wordpress.com/2011/12/viehboeck_wps.pdf |archive-date=2012-01-18 }}</ref><ref>[[US CERT]] [http://www.kb.cert.org/vuls/id/723755 Vulnerability Note VU#723755] {{webarchive|url=https://web.archive.org/web/20120103152902/http://www.kb.cert.org/vuls/id/723755 |date=2012-01-03 }}</ref>

In late 2014, [[Apple Inc.|Apple]] announced that its [[iOS]]&nbsp;8 mobile operating system would scramble MAC addresses during the pre-association stage to thwart [[People counter|retail footfall tracking]] made possible by the regular transmission of uniquely identifiable probe requests.<ref>{{cite web |date=9 June 2014 |title=iOS 8 strikes an unexpected blow against location tracking |url=https://www.theverge.com/2014/6/9/5792970/ios-8-strikes-an-unexpected-blow-against-location-tracking |url-status=live |archive-url=https://web.archive.org/web/20150402001224/http://www.theverge.com/2014/6/9/5792970/ios-8-strikes-an-unexpected-blow-against-location-tracking |archive-date=2015-04-02}}</ref> Android 8.0 "Oreo" introduced a similar feature, named "MAC randomization".<ref>{{cite web |title=Implementing MAC Randomization |url=https://source.android.com/docs/core/connect/wifi-mac-randomization}}</ref>

Wi-Fi users may be subjected to a [[Wi-Fi deauthentication attack]] to eavesdrop, attack passwords, or force the use of another, usually more expensive access point.{{cn|date=October 2024}}

==See also==
* [[802.11 frame types]]
* [[Comparison of wireless data standards]]
* [[Fujitsu Ltd. v. Netgear Inc.]]
* [[Gi-Fi]], a term used by some trade press to refer to faster versions of the IEEE 802.11 standards
* [[LTE-WLAN Aggregation]]
* [[OFDM system comparison table]]
* [[Passive Wi-Fi]]
* [[Reference Broadcast Infrastructure Synchronization]]
* [[TU (time unit)]]
* [[TV White Space Database]]
* [[Ultra-wideband]]
* [[White spaces (radio)]]
* [[Wi-Fi operating system support]]
* [[Wibree]] or Bluetooth low energy
* [[WiGig]]
* [[Wireless USB]] – another wireless protocol primarily designed for shorter-range applications

==Notes==
{{notelist}}
{{notelist-lr}}

==Footnotes==
{{Reflist}}

==References==
{{Refbegin}}<!--All the published 802.11 standards-->
* {{cite book |publisher=[[IEEE-SA]] |date=14 December 2016 |doi=10.1109/IEEESTD.2016.7786995 | version=(2016 revision)|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 }}
* {{cite book |publisher=[[IEEE-SA]] |date=12 June 2008 |doi=10.1109/IEEESTD.2008.4544755 | url=http://standards.ieee.org/getieee802/download/802.11k-2008.pdf| archive-url=https://web.archive.org/web/20090419144934/http://standards.ieee.org/getieee802/download/802.11k-2008.pdf| url-status=dead| archive-date=19 April 2009|isbn=978-0-7381-5420-6 |title=IEEE Standard for Information technology-- Local and metropolitan area networks-- Specific requirements-- Part 11: Wireless LAN Medium Access Control (MAC)and Physical Layer (PHY) Specifications Amendment 1: Radio Resource Measurement of Wireless LANs }}
* {{cite book |publisher=[[IEEE-SA]] |date=15 July 2008 |doi=10.1109/IEEESTD.2008.4573292 | url=http://standards.ieee.org/getieee802/download/802.11r-2008.pdf| archive-url=https://web.archive.org/web/20090206001647/http://standards.ieee.org/getieee802/download/802.11r-2008.pdf| url-status=dead| archive-date=6 February 2009|isbn=978-0-7381-5422-0 |title=IEEE Standard for Information technology-- Local and metropolitan area networks-- Specific requirements-- Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 2: Fast Basic Service Set (BSS) Transition }}
* {{cite book |publisher=[[IEEE-SA]] |date=6 November 2008 |doi=10.1109/IEEESTD.2008.4669928 | url=http://standards.ieee.org/getieee802/download/802.11y-2008.pdf| archive-url=https://web.archive.org/web/20090610171259/http://standards.ieee.org/getieee802/download/802.11y-2008.pdf| url-status=dead| archive-date=10 June 2009|isbn=978-0-7381-5765-8 |title=IEEE Standard for Information technology-- Local and metropolitan area networks-- Specific requirements-- Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 3: 3650-3700 MHZ Operation in USA }}
{{Refend}}

==External links==
<!-- See [[WP:EL]] Do not add any non IEEE articles to this page. Wikipedia is not Google -->
* [http://www.ieee802.org/11/ IEEE 802.11 working group]
* [http://www.ieee802.org/11/Reports/802.11_Timelines.htm Official timelines of 802.11 standards from IEEE]
* [https://web.archive.org/web/20150320233047/https://wikidevi.com/wiki/List_of_Wi-Fi_Chipset_Vendors List of all Wi-Fi Chipset Vendors] – Including historical [[timeline]] of mergers and acquisitions

{{IEEE standards|state=uncollapsed}}
{{cdma}}

[[Category:IEEE 802.11| ]]
[[Category:Computer-related introductions in 1997]]
[[Category:Wireless networking standards]]
[[Category:Local area networks]]
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