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.

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 remains a part of the standard but has no actual implementations.

The original standard also defines carrier sense multiple 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.[1]

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 (Spectrum24), and Proxim Wireless (OpenAir and Rangelan2). 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.

IEEE 802.11 network PHY standards
Frequency range, or type	PHY	Protocol	Release date[2]	Frequency	Bandwidth	Stream data rate[3]	Allowable MIMO streams	Modulation	Approximate range
									Indoor	Outdoor
				(GHz)	(MHz)	(Mbit/s)
1–6 GHz	DSSS/FHSS[4]	802.11-1997	Jun 1997	2.4	22	1, 2	N/A	DSSS, FHSS	20 m (66 ft)	100 m (330 ft)
	HR-DSSS[4]	802.11b	Sep 1999	2.4	22	1, 2, 5.5, 11	N/A	DSSS	35 m (115 ft)	140 m (460 ft)
	OFDM	802.11a	Sep 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)	N/A	OFDM	35 m (115 ft)	120 m (390 ft)
		802.11j	Nov 2004	4.9/5.0^[D][5]					?	?
		802.11p	Jul 2010	5.9					?	1,000 m (3,300 ft)[6]
		802.11y	Nov 2008	3.7^[A]					?	5,000 m (16,000 ft)^[A]
	ERP-OFDM(, etc.)	802.11g	Jun 2003	2.4					38 m (125 ft)	140 m (460 ft)
	HT-OFDM[7]	802.11n	Oct 2009	2.4/5	20	Up to 288.8^[B]	4	MIMO-OFDM	70 m (230 ft)	250 m (820 ft)[8]
					40	Up to 600^[B]
	VHT-OFDM[7]	802.11ac	Dec 2013	5	20	Up to 346.8^[B]	8	MIMO-OFDM	35 m (115 ft)[9]	?
					40	Up to 800^[B]
					80	Up to 1733.2^[B]
					160	Up to 3466.8^[B]
	HE-OFDM	802.11ax	September 2019 [10]	2.4/5/6	20	Up to 1147^[F]	8	MIMO-OFDM	30 m (98 ft)	120 m (390 ft) ^[G]
					40	Up to 2294^[F]
					80	Up to 4804^[F]
					80+80	Up to 9608^[F]
mmWave	DMG[11]	802.11ad	Dec 2012	60	2,160	Up to 6,757[12] (6.7 Gbit/s)	N/A	OFDM, single carrier, low-power single carrier	3.3 m (11 ft)[13]	?
		802.11aj	Apr 2018	45/60^[C]	540/1,080[14]	Up to 15,000[15] (15 Gbit/s)	4[16]	OFDM, single carrier[16]	?	?
	EDMG[17]	802.11ay	Est. May 2020	60	8000	Up to 20,000 (20 Gbit/s)[18]	4	OFDM, single carrier	10 m (33 ft)	100 m (328 ft)
Sub-1 GHz IoT	TVHT[19]	802.11af	Feb 2014	0.054–0.79	6–8	Up to 568.9[20]	4	MIMO-OFDM	?	?
	S1G[19]	802.11ah	Dec 2016	0.7/0.8/0.9	1–16	Up to 8.67 (@2 MHz)[21]	4		?	?
2.4 GHz, 5 GHz	WUR	802.11ba^[E]	Est. Sep 2020	2.4/5	4.06	0.0625, 0.25 (62.5 kbit/s, 250 kbit/s)	N/A	OOK (Multi-carrier OOK)	?	?
Light (Li-Fi)	IR	802.11-1997	Jun 1997	?	?	1, 2	N/A	PPM	?	?
	?	802.11bb	Est. Jul 2021	60000-790000	?	?	N/A	?	?	?
802.11 Standard rollups
		802.11-2007	Mar 2007	2.4, 5		Up to 54		DSSS, OFDM
		802.11-2012	Mar 2012	2.4, 5		Up to 150^[B]		DSSS, OFDM
		802.11-2016	Dec 2016	2.4, 5, 60		Up to 866.7 or 6,757^[B]		DSSS, OFDM
^A1 ^A2 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. ^B1 ^B2 ^B3 ^B4 ^B5 ^B6 Based on short guard interval; standard guard interval is ~10% slower. Rates vary widely based on distance, obstructions, and interference. ^C1 For Chinese regulation. ^D1 For Japanese regulation. ^E1 Wake-up Radio (WUR) Operation. ^F1 ^F2 ^F3 ^F4 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. ^G1 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.

References

1. Maufer, Thomas (2004). A Field Guide to Wireless LANs: For Administrators and Power Users. The Radia Perlman Series in Computer Networking and Security Series. Prentice Hall Professional. p. 144. ISBN 9780131014060. 0131014064. Retrieved 2015-10-27.
2. "Official IEEE 802.11 working group project timelines". January 26, 2017. Retrieved 2017-02-12.
3. "Wi-Fi CERTIFIED n: Longer-Range, Faster-Throughput, Multimedia-Grade Wi-Fi® Networks" (PDF). Wi-Fi Alliance. September 2009.
4. Banerji, Sourangsu; Chowdhury, Rahul Singha. "On IEEE 802.11: Wireless LAN Technology". arXiv:1307.2661.
5. "The complete family of wireless LAN standards: 802.11 a, b, g, j, n" (PDF).
6. Abdelgader, Abdeldime M.S.; Wu, Lenan (2014). The Physical Layer of the IEEE 802.11p WAVE Communication Standard: The Specifications and Challenges (PDF). World Congress on Engineering and Computer Science.
7. Wi-Fi Capacity Analysis for 802.11ac and 802.11n: Theory & Practice
8. Belanger, Phil; Biba, Ken (2007-05-31). "802.11n Delivers Better Range". Wi-Fi Planet. Archived from the original on 2008-11-24.
9. "IEEE 802.11ac: What Does it Mean for Test?" (PDF). LitePoint. October 2013. Archived from the original (PDF) on 2014-08-16.
10. "Wi-Fi 6 Routers: What You Can Buy Now (and Soon) | Tom's Guide". www.tomsguide.com.
11. "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 3: Enhancements for Very High Throughput to Support Chinese Millimeter Wave Frequency Bands (60 GHz and 45 GHz)". IEEE Std 802.11aj-2018. April 2018. doi:10.1109/IEEESTD.2018.8345727.
12. "802.11ad - WLAN at 60 GHz: A Technology Introduction" (PDF). Rohde & Schwarz GmbH. November 21, 2013. p. 14.
13. "Connect802 - 802.11ac Discussion". www.connect802.com.
14. "Understanding IEEE 802.11ad Physical Layer and Measurement Challenges" (PDF).
15. "802.11aj Press Release".
16. Hong, Wei; He, Shiwen; Wang, Haiming; Yang, Guangqi; Huang, Yongming; Chen, Jixing; Zhou, Jianyi; Zhu, Xiaowei; Zhang, Nianzhu; Zhai, Jianfeng; Yang, Luxi; Jiang, Zhihao; Yu, Chao (2018). "An Overview of China Millimeter-Wave Multiple Gigabit Wireless Local Area Network System". IEICE Transactions on Communications. E101.B (2): 262–276. doi:10.1587/transcom.2017ISI0004.
17. "IEEE 802.11ay: 1st real standard for Broadband Wireless Access (BWA) via mmWave – Technology Blog". techblog.comsoc.org.
18. Sun, Rob; Xin, Yan; Aboul-Maged, Osama; Calcev, George; Wang, Lei; Au, Edward; Cariou, Laurent; Cordeiro, Carlos; Abu-Surra, Shadi; Chang, Sanghyun; Taori, Rakesh; Kim, TaeYoung; Oh, Jongho; Cho, JanGyu; Motozuka, Hiroyuki; Wee, Gaius. "P802.11 Wireless LANs". IEEE. pp. 2, 3. Archived from the original on 2017-12-06. Retrieved December 6, 2017.
19. "802.11 Alternate PHYs A whitepaper by Ayman Mukaddam" (PDF).
20. Lee, Wookbong; Kwak, Jin-Sam; Kafle, Padam; Tingleff, Jens; Yucek, Tevfik; Porat, Ron; Erceg, Vinko; Lan, Zhou; Harada, Hiroshi (2012-07-10). "TGaf PHY proposal". IEEE P802.11. Retrieved 2013-12-29.
21. Sun, Weiping; Choi, Munhwan; Choi, Sunghyun (July 2013). "IEEE 802.11ah: A Long Range 802.11 WLAN at Sub 1 GHz" (PDF). Journal of ICT Standardization. 1 (1): 83–108. doi:10.13052/jicts2245-800X.115.

Further reading

• IEEE 802.11 Working Group (1997-11-18). IEEE 802.11-1997: 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 802.11-1999: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. doi:10.1109/IEEESTD.2003.95617. ISBN 0-7381-1857-5.