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IEEE 802.11 is part of the IEEE 802 set of local area network (LAN) technical standards, 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/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 the original 1997 version.
IEEE 802.11 uses various frequencies including, but not limited to, 2.4 GHz, 5 GHz, 6 GHz, and 60 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.
| Generation | IEEE standard |
Adopted | Maximum link rate (Mbit/s) |
Radio frequency (GHz) |
|---|---|---|---|---|
| Wi-Fi 8 | 802.11bn | 2028[1] | 100,000[2] | 2.4, 5, 6, 7, 42.5, 71[3] |
| Wi-Fi 7 | 802.11be | 2024 | 1376–46,120 | 2.4, 5, 6[4] |
| Wi-Fi 6E | 802.11ax | 2020 | 574–9608[5] | 6[a] |
| Wi-Fi 6 | 2019 | 2.4, 5 | ||
| Wi-Fi 5 | 802.11ac | 2014 | 433–6933 | 5[b] |
| Wi-Fi 4 | 802.11n | 2008 | 72–600 | 2.4, 5 |
| (Wi-Fi 3)* | 802.11g | 2003 | 6–54 | 2.4 |
| (Wi-Fi 2)* | 802.11a | 1999 | 5 | |
| (Wi-Fi 1)* | 802.11b | 1999 | 1–11 | 2.4 |
| (Wi-Fi 0)* | 802.11 | 1997 | 1–2 | 2.4 |
| *Wi‑Fi 0, 1, 2, and 3 are named by retroactive inference. They do not exist in the official nomenclature.[6][7][8] | ||||
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.[9]
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 interference in the 2.4-GHz band from microwave ovens, cordless telephones, 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 5 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 GHz or 5 GHz band; 802.11ac uses only the 5 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 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.[10]
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 1–6 use the 802.11b, 802.11a, 802.11g, 802.11n, 802.11ac, and 802.11ax protocols, in that order.[11][12]
History
802.11 technology has its origins in a 1985 ruling by the U.S. Federal Communications Commission that released the ISM band[9] for unlicensed use.[13]
In 1991 NCR 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 Mbit/s and 2 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.[14] He, along with Bell Labs Engineer Bruce Tuch, approached IEEE to create a standard.[15]
In 1999, the Wi-Fi Alliance was formed as a trade association to hold the Wi-Fi trademark under which most products are sold.[16]
The major commercial breakthrough came with 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.[17][18][19] One year later IBM followed with its ThinkPad 1300 series in 2000.[20]
Protocol
| Frequency range, or type |
PHY | Protocol | Release date [21] |
Frequency | Bandwidth | Stream data rate [22] |
Allowable MIMO streams |
Modulation | Approximate range | |
|---|---|---|---|---|---|---|---|---|---|---|
| Indoor | Outdoor | |||||||||
| (GHz) | (MHz) | (Mbit/s) | ||||||||
| 1–7 GHz | DSSS[23], |
802.11-1997 | June 1997 | 2.4 | 22 | 1, 2 | — | DSSS, |
20 m (66 ft) | 100 m (330 ft) |
| HR/DSSS [23] | 802.11b | September 1999 | 2.4 | 22 | 1, 2, 5.5, 11 | — | CCK, DSSS | 35 m (115 ft) | 140 m (460 ft) | |
| OFDM | 802.11a | September 1999 | 5 | 5, 10, 20 | 6, 9, 12, 18, 24, 36, 48, 54 (for 20 MHz bandwidth, divide by 2 and 4 for 10 and 5 MHz) |
— | OFDM | 35 m (115 ft) | 120 m (390 ft) | |
| 802.11j | November 2004 | 4.9, 5.0 [B][24] |
? | ? | ||||||
| 802.11y | November 2008 | 3.7 [C] | ? | 5,000 m (16,000 ft)[C] | ||||||
| 802.11p | July 2010 | 5.9 | 200 m | 1,000 m (3,300 ft)[25] | ||||||
| 802.11bd | December 2022 | 5.9, 60 | 500 m | 1,000 m (3,300 ft) | ||||||
| ERP-OFDM[26] | 802.11g | June 2003 | 2.4 | 38 m (125 ft) | 140 m (460 ft) | |||||
| HT-OFDM [27] | 802.11n (Wi-Fi 4) |
October 2009 | 2.4, 5 | 20 | Up to 288.8[D] | 4 | MIMO-OFDM (64-QAM) |
70 m (230 ft) | 250 m (820 ft)[28] | |
| 40 | Up to 600[D] | |||||||||
| VHT-OFDM [27] | 802.11ac (Wi-Fi 5) |
December 2013 | 5 | 20 | Up to 693[D] | 8 | DL MU-MIMO OFDM (256-QAM) |
35 m (115 ft)[29] | ? | |
| 40 | Zdroj:https://en.wikipedia.org?pojem=IEEE_802.11m||||||||||