IEEE 802.11 (legacy mode)

IEEE 802.11 (legacy mode) – or more correctly IEEE 802.11-1997 or IEEE 802.11-1999 – refer to the original version of the IEEE 802.11 wireless networking standard released in 1997 and clarified in 1999. Most of the protocols described by this early version are rarely used today.

Wi-Fi generations
Generation IEEE
standard		 Adopted Maximum
link rate
(Mbit/s)		 Radio
frequency
(GHz)
Wi-Fi 7 802.11be (2024) 1376 to 46120 2.4/5/6
Wi-Fi 6E 802.11ax 2020 574 to 9608[1] 6[lower-alpha 1]
Wi-Fi 6 2019 2.4/5
Wi-Fi 5 802.11ac 2014 433 to 6933 5[lower-alpha 2]
Wi-Fi 4 802.11n 2008 72 to 600 2.4/5
(Wi-Fi 3)* 802.11g 2003 6 to 54 2.4
(Wi-Fi 2)* 802.11a 1999 5
(Wi-Fi 1)* 802.11b 1999 1 to 11 2.4
(Wi-Fi 0)* 802.11 1997 1 to 2 2.4
*Wi-Fi 0, 1, 2, and 3 are by retroactive inference [2][3][4]

Description

It specified two raw data rates of 1 and 2 megabits per second (Mbit/s) to be transmitted via infrared (IR) signals or by either frequency hopping or direct-sequence spread spectrum (DSSS) in the Industrial Scientific Medical frequency band at 2.4  GHz. IR remained a part of the standard until IEEE 802.11-2016, but was never implemented.

The original standard also defines carrier sense 0 access with collision avoidance (CSMA/CA) as the medium access method. A significant percentage of the available raw channel capacity is sacrificed (via the CSMA/CA mechanisms) in order to improve the reliability of data transmissions under diverse and adverse environmental conditions.

IEEE 802.11-1999 also introduced the binary time unit TU defined as 1024 µs.[5]

At least six different, somewhat-interoperable, commercial products appeared using the original specification, from companies like Alvarion (PRO.11 and BreezeAccess-II), BreezeCom, Digital / Cabletron (RoamAbout), Lucent, Netwave Technologies (AirSurfer Plus and AirSurfer Pro), Symbol Technologies (Spectrum25), and Proxim Wireless (OpenAir and Rangela2). A weakness of this original specification was that it offered so many choices that interoperability was sometimes challenging to realize. It is really more of a "beta specification" than a rigid specification, initially allowing individual product vendors the flexibility to differentiate their products but with little to no inter-vendor operability.

The DSSS version of legacy 802.11 was rapidly supplemented (and popularized) by the 802.11b amendment in 1999, which increased the bit rate to 11 Mbit/s. Widespread adoption of 802.11 networks only occurred after the release of 802.11b which resulted in multiple interoperable products becoming available from multiple vendors. Consequently, comparatively few networks were implemented on the 802.11-1997 standard.

Comparison
802.11 network standards
Frequency
range,
or type		 PHY Protocol Release
date [6]		 Frequency Bandwidth Stream
data rate [7]		 Allowable
MIMO streams		 Modulation Approximate
range
Indoor Outdoor
(GHz) (MHz) (Mbit/s)
1–7⅛ GHz DSSS[8], FHSS[upper-alpha 1] 802.11-1997 June 1997 2.4 22 1, 2 — DSSS, FHSS[upper-alpha 1] 20 m (66 ft) 100 m (330 ft)
HR/DSSS [8] 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
[upper-alpha 2][9]		 ? ?
802.11y November 2008 3.7 [upper-alpha 3] ? 5,000 m (16,000 ft)[upper-alpha 3]
802.11p July 2010 5.9 200 m 1,000 m (3,300 ft)[10]
802.11bd December 2022 5.9/60 500 m 1,000 m (3,300 ft)
ERP-OFDM 802.11g June 2003 2.4 38 m (125 ft) 140 m (460 ft)
HT-OFDM [11] 802.11n
(Wi-Fi 4)		 October 2009 2.4/5 20 Up to 288.8[upper-alpha 4] 4 MIMO-OFDM
(64-QAM)		 70 m (230 ft) 250 m (820 ft)[12]
40 Up to 600[upper-alpha 4]
VHT-OFDM [11] 802.11ac
(Wi-Fi 5)		 December 2013 5 20 Up to 693[upper-alpha 4] 8 DL
MU-MIMO OFDM
(256-QAM)		 35 m (115 ft)[13] ?
40 Up to 1600[upper-alpha 4]
80 Up to 3467[upper-alpha 4]
160 Up to 6933[upper-alpha 4]
HE-OFDMA 802.11ax
(Wi-Fi 6,
Wi-Fi 6E)		 May 2021 2.4/5/6 20 Up to 1147[upper-alpha 5] 8 UL/DL
MU-MIMO OFDMA
(1024-QAM)		 30 m (98 ft) 120 m (390 ft) [upper-alpha 6]
40 Up to 2294[upper-alpha 5]
80 Up to 4804[upper-alpha 5]
80+80 Up to 9608[upper-alpha 5]
EHT-OFDMA 802.11be
(Wi-Fi 7)		 May 2024
(est.)		 2.4/5/6 80 Up to 11.5 Gbit/s[upper-alpha 5] 16 UL/DL
MU-MIMO OFDMA
(4096-QAM)		 30 m (98 ft) 120 m (390 ft) [upper-alpha 6]
160
(80+80)		 Up to 23 Gbit/s[upper-alpha 5]
240
(160+80)		 Up to 35 Gbit/s[upper-alpha 5]
320
(160+160)		 Up to 46.1 Gbit/s[upper-alpha 5]
WUR [upper-alpha 7] 802.11ba October 2021 2.4/5 4/20 0.0625, 0.25
(62.5 kbit/s, 250 kbit/s)		 — OOK (multi-carrier OOK) ? ?
mmWave
(WiGig)		 DMG [14] 802.11ad December 2012 60 2160
(2.16 GHz)		 Up to 8085[15]
(8 Gbit/s)		 — OFDM[upper-alpha 1], single carrier, low-power single carrier[upper-alpha 1] 3.3 m (11 ft)[16] ?
802.11aj April 2018 60 [upper-alpha 8] 1080[17] Up to 3754
(3.75 Gbit/s)		 — single carrier, low-power single carrier[upper-alpha 1] ? ?
CMMG 802.11aj April 2018 45 [upper-alpha 8] 540/
1080		 Up to 15015[18]
(15 Gbit/s)		 4[19] OFDM, single carrier ? ?
EDMG [20] 802.11ay July 2021 60 Up to 8640
(8.64 GHz)		 Up to 303336[21]
(303 Gbit/s)		 8 OFDM, single carrier 10 m (33 ft) 100 m (328 ft)
Sub 1 GHz (IoT) TVHT [22] 802.11af February 2014 0.054
-0.79		 6, 7, 8 Up to 568.9[23] 4 MIMO-OFDM ? ?
S1G [22] 802.11ah May 2017 0.7/0.8
/0.9		 1–16 Up to 8.67[24]
(@2 MHz)		 4 ? ?
Light
(Li-Fi)		 LC
(VLC/OWC)		 802.11bb December 2023
(est.)		 800–1000 nm 20 Up to 9.6 Gbit/s — O-OFDM ? ?
IR[upper-alpha 1]
(IrDA)		 802.11-1997 June 1997 850–900 nm ? 1, 2 — PPM[upper-alpha 1] ? ?
802.11 Standard rollups
  802.11-2007 (802.11ma) March 2007 2.4, 5 Up to 54 DSSS, OFDM
802.11-2012 (802.11mb) March 2012 2.4, 5 Up to 150[upper-alpha 4] DSSS, OFDM
802.11-2016 (802.11mc) December 2016 2.4, 5, 60 Up to 866.7 or 6757[upper-alpha 4] DSSS, OFDM
802.11-2020 (802.11md) December 2020 2.4, 5, 60 Up to 866.7 or 6757[upper-alpha 4] DSSS, OFDM
802.11me September 2024
(est.)		 2.4, 5, 6, 60 Up to 9608 or 303336 DSSS, OFDM
  1. This is obsolete, and support for this might be subject to removal in a future revision of the standard
  2. For Japanese regulation.
  3. IEEE 802.11y-2008 extended operation of 802.11a to the licensed 3.7 GHz band. Increased power limits allow a range up to 5,000 m. As of 2009, it is only being licensed in the United States by the FCC.
  4. Based on short guard interval; standard guard interval is ~10% slower. Rates vary widely based on distance, obstructions, and interference.
  5. For single-user cases only, based on default guard interval which is 0.8 micro seconds. Since multi-user via OFDMA has become available for 802.11ax, these may decrease. Also, these theoretical values depend on the link distance, whether the link is line-of-sight or not, interferences and the multi-path components in the environment.
  6. The default guard interval is 0.8 micro seconds. However, 802.11ax extended the maximum available guard interval to 3.2 micro seconds, in order to support Outdoor communications, where the maximum possible propagation delay is larger compared to Indoor environments.
  7. Wake-up Radio (WUR) Operation.
  8. For Chinese regulation.

Notes
  1. Wi-Fi 6E is the industry name that identifies Wi-Fi devices that operate in 6 GHz. Wi-Fi 6E offers the features and capabilities of Wi-Fi 6 extended into the 6 GHz band.
  2. 802.11ac only specifies operation in the 5 GHz band. Operation in the 2.4 GHz band is specified by 802.11n.

References
  1. "MCS table (updated with 80211ax data rates)". semfionetworks.com.
  2. Kastrenakes, Jacob (2018-10-03). "Wi-Fi Now Has Version Numbers, and Wi-Fi 6 Comes Out Next Year". The Verge. Retrieved 2019-05-02.
  3. Phillips, Gavin (18 January 2021). "The Most Common Wi-Fi Standards and Types, Explained". MUO - Make Use Of. Archived from the original on 11 November 2021. Retrieved 9 November 2021.
  4. "Wi-Fi Generation Numbering". ElectronicsNotes. Archived from the original on 11 November 2021. Retrieved 10 November 2021.
  5. Maufer, Thomas (2004). A Field Guide to Wireless LANs: For Administrators and Power Users. p. 144. ISBN 9780131014060. 0131014064. Retrieved 2015-10-27. {{cite book}}: |work= ignored (help)
  6. "Official IEEE 802.11 working group project timelines". January 26, 2017. Retrieved 2017-02-12.
  7. "Wi-Fi CERTIFIED n: Longer-Range, Faster-Throughput, Multimedia-Grade Wi-Fi Networks" (PDF). Wi-Fi Alliance. September 2009.
  8. Banerji, Sourangsu; Chowdhury, Rahul Singha. "On IEEE 802.11: Wireless LAN Technology". arXiv:1307.2661.
  9. "The complete family of wireless LAN standards: 802.11 a, b, g, j, n" (PDF).
  10. The Physical Layer of the IEEE 802.11p WAVE Communication Standard: The Specifications and Challenges (PDF). World Congress on Engineering and Computer Science. 2014.
  11. "Wi-Fi Capacity Analysis for 802.11ac and 802.11n: Theory & Practice" (PDF).
  12. Belanger, Phil; Biba, Ken (2007-05-31). "802.11n Delivers Better Range". Wi-Fi Planet. Archived from the original on 2008-11-24.
  13. "IEEE 802.11ac: What Does it Mean for Test?" (PDF). LitePoint. October 2013. Archived from the original (PDF) on 2014-08-16.
  14. "IEEE Standard for Information Technology". IEEE Std 802.11aj-2018. April 2018. doi:10.1109/IEEESTD.2018.8345727.
  15. "802.11ad - WLAN at 60 GHz: A Technology Introduction" (PDF). Rohde & Schwarz GmbH. November 21, 2013. p. 14.
  16. "Connect802 - 802.11ac Discussion". www.connect802.com.
  17. "Understanding IEEE 802.11ad Physical Layer and Measurement Challenges" (PDF).
  18. "802.11aj Press Release".
  19. "An Overview of China Millimeter-Wave Multiple Gigabit Wireless Local Area Network System". IEICE Transactions on Communications. E101.B (2): 262–276. 2018. doi:10.1587/transcom.2017ISI0004.
  20. "IEEE 802.11ay: 1st real standard for Broadband Wireless Access (BWA) via mmWave – Technology Blog". techblog.comsoc.org.
  21. "P802.11 Wireless LANs". IEEE. pp. 2, 3. Archived from the original on 2017-12-06. Retrieved Dec 6, 2017.
  22. "802.11 Alternate PHYs A whitepaper by Ayman Mukaddam" (PDF).
  23. "TGaf PHY proposal". IEEE P802.11. 2012-07-10. Retrieved 2013-12-29.
  24. "IEEE 802.11ah: A Long Range 802.11 WLAN at Sub 1 GHz" (PDF). Journal of ICT Standardization. 1 (1): 83–108. July 2013. doi:10.13052/jicts2245-800X.115.

Further reading
  • IEEE 802.11 Working Group (1997-11-18). IEEE Standard for Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications. doi:10.1109/IEEESTD.1997.85951. ISBN 1-55937-935-9.
  • IEEE 802.11 Working Group (1999-07-15). 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. doi:10.1109/IEEESTD.2003.95617. ISBN 0-7381-1857-5.
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