IEEE 802.11g-2003

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IEEE 802.11g-2003 or 802.11g is an amendment to the IEEE 802.11 specification that operates in the 2.4 GHz microwave band. The standard has extended throughput to up to 54 Mbit/s using the same 20MHz bandwidth as 802.11b uses to achieve 11 Mbit/s. This specification under the marketing name of Wi-Fi has been implemented all over the world. The 802.11g protocol is now Clause 19 of the published IEEE 802.11-2007 standard, and Clause 19 of the published IEEE 802.11-2012 standard.

802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac and 802.11ax versions to provide wireless connectivity in the home, office and some commercial establishments.

802.11g is fully backward compatible with 802.11b.

Descriptions[edit]

802.11g is the third modulation standard for wireless LANs. It works in the 2.4 GHz band (like 802.11b) but operates at a maximum raw data rate of 54 Mbit/s. Using the CSMA/CA transmission scheme, 31.4 Mbit/s[1] is the maximum net throughput possible for packets of 1500 bytes in size and a 54 Mbit/s wireless rate (identical to 802.11a core, except for some additional legacy overhead for backward compatibility). In practice, access points may not have an ideal implementation and may therefore not be able to achieve even 31.4 Mbit/s throughput with 1500 byte packets. 1500 bytes is the usual limit for packets on the Internet and therefore a relevant size to benchmark against. Smaller packets give even lower theoretical throughput, down to 3 Mbit/s using 54 Mbit/s rate and 64 byte packets.[1] Also, the available throughput is shared between all stations transmitting, including the AP so both downstream and upstream traffic is limited to a shared total of 31.4 Mbit/s using 1500 byte packets and 54 Mbit/s rate.

802.11g hardware is fully backward compatible with 802.11b hardware. Details of making b and g work well together occupied much of the lingering technical process. In an 802.11g network, however, the presence of a legacy 802.11b participant will significantly reduce the speed of the overall 802.11g network. Some 802.11g routers employ a back-compatible mode for 802.11b clients called 54g LRS (Limited Rate Support).

The modulation scheme used in 802.11g is orthogonal frequency-division multiplexing (OFDM) copied from 802.11a with data rates of 6, 9, 12, 18, 24, 36, 48, and 54 Mbit/s, and reverts to CCK (like the 802.11b standard) for 5.5 and 11 Mbit/s and DBPSK/DQPSK+DSSS for 1 and 2 Mbit/s. Even though 802.11g operates in the same frequency band as 802.11b, it can achieve higher data rates because of its heritage to 802.11a.

Technical description[edit]

Of the 52 OFDM subcarriers, 48 are for data and 4 are pilot subcarriers with a carrier separation of 0.3125 MHz (20 MHz/64). Each of these subcarriers can be a BPSK, QPSK, 16-QAM or 64-QAM. The total bandwidth is 22 MHz with an occupied bandwidth of 16.6 MHz. Symbol duration is 4 microseconds, which includes a guard interval of 0.8 microseconds. The actual generation and decoding of orthogonal components is done in baseband using DSP which is then upconverted to 2.4 GHz at the transmitter. Each of the subcarriers could be represented as a complex number. The time domain signal is generated by taking an Inverse Fast Fourier transform (IFFT). Correspondingly the receiver downconverts, samples at 20 MHz and does an FFT to retrieve the original coefficients. The advantages of using OFDM include reduced multipath effects in reception and increased spectral efficiency.[2]

MCS index(read as little endian) RATE bits R1-R4 Modulation
type
Coding
rate
Data rate
(Mbit/s)
11 1101 BPSK 1/2 6
15 1111 BPSK 3/4 9
10 0101 QPSK 1/2 12
14 0111 QPSK 3/4 18
9 1001 16-QAM 1/2 24
13 1011 16-QAM 3/4 36
8 0001 64-QAM 2/3 48
12 0011 64-QAM 3/4 54

Adoption[edit]

The then-proposed 802.11g standard was rapidly adopted by consumers starting in January 2003, well before ratification, due to the desire for higher speeds and reductions in manufacturing costs. By mid-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.[citation needed]

Despite its major acceptance, 802.11g suffers from the same interference as 802.11b in the already crowded 2.4 GHz range. Devices operating in this range include microwave ovens, Bluetooth devices, baby monitors, and digital cordless telephones, which can lead to interference issues. Additionally, the success of the standard has caused usage/density problems related to crowding in urban areas. To prevent interference, there are only three non-overlapping usable channels in the U.S. and other countries with similar regulations (channels 1, 6, 11, with 25 MHz separation), and four in Europe (channels 1, 5, 9, 13, with only 20 MHz separation). Even with such separation, some interference due to side lobes exists, though it is considerably weaker.

Channels and frequencies[edit]

Spirt ec:4d:47:33:04:c0 2412 MHz, CH. 1 [WPA2-PSK-CCMP+TKIP][RSN-PSK-CCMP+TKIP][WPA-PSK-CCMP+TKIP][ESS][WFA-HT] HUAWEI TECHNOLOGIES CO., LTD
802.11b/g channels in 2.4 GHz band
IEEE 802.11g channel to frequency map [3]
Channel Center frequency Channel width Overlapping channels
1 2.412 GHz 2.401 GHz - 2.423 GHz 2,3,4,5
2 2.417 GHz 2.406 GHz - 2.428 GHz 1,3,4,5,6
3 2.422 GHz 2.411 GHz - 2.433 GHz 1,2,4,5,6,7
4 2.427 GHz 2.416 GHz - 2.438 GHz 1,2,3,5,6,7,8
5 2.432 GHz 2.421 GHz - 2.443 GHz 1,2,3,4,6,7,8,9
6 2.437 GHz 2.426 GHz - 2.448 GHz 2,3,4,5,7,8,9,10
7 2.442 GHz 2.431 GHz - 2.453 GHz 3,4,5,6,8,9,10,11
8 2.447 GHz 2.436 GHz - 2.458 GHz 4,5,6,7,9,10,11,12
9 2.452 GHz 2.441 GHz - 2.463 GHz 5,6,7,8,10,11,12,13
10 2.457 GHz 2.446 GHz - 2.468 GHz 6,7,8,9,11,12,13
11 2.462 GHz 2.451 GHz - 2.473 GHz 7,8,9,10,12,13
12 2.467 GHz 2.456 GHz - 2.478 GHz 8,9,10,11,13,14
13 2.472 GHz 2.461 GHz - 2.483 GHz 9,10,11,12,14
14 2.484 GHz 2.473 GHz - 2.495 GHz 12,13
Note: Not all channels are legal to use in all countries.

See also[edit]

Frequency
range, or type
PHY Protocol Release date[4] Frequency Bandwidth Stream data rate[5] Allowable
MIMO streams
Modulation Approximate range[citation needed]
Indoor Outdoor
(GHz) (MHz) (Mbit/s)
1–6 GHz DSSS/FHSS[6] 802.11-1997 Jun 1997 2.4 22 1, 2 N/A DSSS, FHSS 20 m (66 ft) 100 m (330 ft)
HR-DSSS[6] 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][7][failed verification] ? ?
802.11p Jul 2010 5.9 ? 1,000 m (3,300 ft)[8]
802.11y Nov 2008 3.7[A] ? 5,000 m (16,000 ft)[A]
ERP-OFDM 802.11g Jun 2003 2.4 38 m (125 ft) 140 m (460 ft)
HT-OFDM[9] 802.11n (Wi-Fi 4) Oct 2009 2.4/5 20 Up to 288.8[B] 4 MIMO-OFDM 70 m (230 ft) 250 m (820 ft)[10][failed verification]
40 Up to 600[B]
VHT-OFDM[9] 802.11ac (Wi-Fi 5) Dec 2013 5 20 Up to 346.8[B] 8 MIMO-OFDM 35 m (115 ft)[11] ?
40 Up to 800[B]
80 Up to 1733.2[B]
160 Up to 3466.8[B]
HE-OFDMA 802.11ax (Wi-Fi 6) Feb 2021 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[12] 802.11ad Dec 2012 60 2,160 Up to 6,757[13]
(6.7 Gbit/s)
N/A OFDM, single carrier, low-power single carrier 3.3 m (11 ft)[14] ?
802.11aj Apr 2018 45/60[C] 540/1,080[15] Up to 15,000[16]
(15 Gbit/s)
4[17] OFDM, single carrier[17] ? ?
EDMG[18] 802.11ay Est. March 2021 60 8000 Up to 20,000 (20 Gbit/s)[19] 4 OFDM, single carrier 10 m (33 ft) 100 m (328 ft)
Sub-1 GHz IoT TVHT[20] 802.11af Feb 2014 0.054–0.79 6–8 Up to 568.9[21] 4 MIMO-OFDM ? ?
S1G[20] 802.11ah Dec 2016 0.7/0.8/0.9 1–16 Up to 8.67 (@2 MHz)[22] 4 ? ?
2.4 GHz, 5 GHz WUR 802.11ba[E] Est. March 2021 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 2022 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
802.11-2020 Dec 2020 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[edit]

  • "IEEE 802.11g-2003: Further Higher Data Rate Extension in the 2.4 GHz Band" (PDF). IEEE. 2003-10-20. Archived from the original (PDF) on July 23, 2004. Retrieved 2007-09-24.
  1. ^ a b Jun, Jangeun; Peddabachagari, Pushkin; Sichitiu, Mihail (2003). "Theoretical Maximum Throughput of IEEE 802.11 and its Applications" (PDF). Proceedings of the Second IEEE International Symposium on Network Computing and Applications. Archived (PDF) from the original on 2014-03-20.
  2. ^ Van Nee, Richard; Awater, Geert; Morikura, Masahiro; Takanashi, Hitoshi; Webster, Mark; Halford, Karen (December 1999). "New High Rate Wireless LAN Standards". IEEE Communications Magazine.
  3. ^ [1][permanent dead link]
  4. ^ "Official IEEE 802.11 working group project timelines". January 26, 2017. Retrieved 2017-02-12.
  5. ^ "Wi-Fi CERTIFIED n: Longer-Range, Faster-Throughput, Multimedia-Grade Wi-Fi® Networks" (PDF). Wi-Fi Alliance. September 2009.[dead link]
  6. ^ a b Banerji, Sourangsu; Chowdhury, Rahul Singha. "On IEEE 802.11: Wireless LAN Technology". arXiv:1307.2661.
  7. ^ "The complete family of wireless LAN standards: 802.11 a, b, g, j, n" (PDF).
  8. ^ 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.
  9. ^ a b Wi-Fi Capacity Analysis for 802.11ac and 802.11n: Theory & Practice
  10. ^ Belanger, Phil; Biba, Ken (2007-05-31). "802.11n Delivers Better Range". Wi-Fi Planet. Archived from the original on 2008-11-24.
  11. ^ "IEEE 802.11ac: What Does it Mean for Test?" (PDF). LitePoint. October 2013. Archived from the original (PDF) on 2014-08-16.
  12. ^ "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.
  13. ^ "802.11ad - WLAN at 60 GHz: A Technology Introduction" (PDF). Rohde & Schwarz GmbH. November 21, 2013. p. 14.
  14. ^ "Connect802 - 802.11ac Discussion". www.connect802.com.
  15. ^ "Understanding IEEE 802.11ad Physical Layer and Measurement Challenges" (PDF).
  16. ^ "802.11aj Press Release".
  17. ^ a b 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.
  18. ^ "IEEE 802.11ay: 1st real standard for Broadband Wireless Access (BWA) via mmWave – Technology Blog". techblog.comsoc.org.
  19. ^ 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.
  20. ^ a b "802.11 Alternate PHYs A whitepaper by Ayman Mukaddam" (PDF).
  21. ^ 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.
  22. ^ 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.