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| Descriptions | |
| 2>
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, or about 19 Mbit/s net throughput[citation needed] (identical to 802.11a core, except for some additional legacy overhead for backward compatibility). 802.11g hardware is fully backwards 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.
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.
[edit] Tags:Mbit/s,Ghz,802.11b,802.11,802.11a,Wireless Lans,Throughput,Orthogonal Frequency-division Multiplexing,Cck,Dbpsk,Dqpsk,Data Rate,Dsss,A,Ofdm,B,N,802,.1,P,Q,X,Ad,Ag,Ak,.4,.5,.11,D,E,F,H,I,K,R,S,U,V,W,Y,Ac, | |
| Adoption | |
| 2>
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 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.
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.
[edit] Tags:Bluetooth,Side Lobes,J, | |
| Channels and Frequencies | |
| 2>
802.11b/g channels in 2.4 GHz band
IEEE 802.11g channel to frequency map [1]
Channel
Center Frequency
Channel Width
Overlaps 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
13
2.472 GHz
2.461 GHz - 2.483 GHz
9,10,11,12
Note: Not all channels are legal to use in all countries.
[edit] Tags:Ieee 802.11,Ieee, | |
| See also | |
| 2>
List of WLAN channels
OFDM system comparison table
Spectral efficiency comparison table
Wi-Fi
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[update], it is only being licensed in the United States by the FCC.
B1 B2 Assumes short guard interval (SGI) enabled, otherwise reduce each data rate by 10%.
v
d
e
802.11 network standards
802.11
protocol
Release[2]
Freq.
(GHz)
Bandwidth
(MHz)
Data rate per stream
(Mbit/s)[3]
Allowable
MIMO streams
Modulation
Approximate indoor range[citation needed]
Approximate outdoor range[citation needed]
(m)
(ft)
(m)
(ft)
—
Jun 1997
2.4
20
1, 2
1
DSSS, FHSS
20
66
100
330
a
Sep 1999
5
20
6, 9, 12, 18, 24, 36, 48, 54
1
OFDM
35
115
120
390
3.7[A]
—
—
5,000
16,000[A]
b
Sep 1999
2.4
20
5.5, 11
1
DSSS
38
125
140
460
g
Jun 2003
2.4
20
6, 9, 12, 18, 24, 36, 48, 54
1
OFDM, DSSS
38
125
140
460
n
Oct 2009
2.4/5
20
7.2, 14.4, 21.7, 28.9, 43.3, 57.8, 65, 72.2[B]
4
OFDM
70
230
250
820[4]
40
15, 30, 45, 60, 90, 120, 135, 150[B]
70
230
250
820[4]
ac (DRAFT)
Nov. 2011
5
80
433, 867
8
160
867, 1.73 Gbit/s, 3.47 Gbit/s, 6.93 Gbit/s
[edit] Tags:List Of Wlan Channels,Ofdm System Comparison Table,Spectral Efficiency Comparison Table,Wi-fi,Fcc,Guard Interval,Mimo,—,Fhss,Ac (draft),Standards,.2,.3, | |
| References | |
| 2>
"IEEE 802.11g-2003: Further Higher Data Rate Extension in the 2.4 GHz Band" (pdf). IEEE. 2003-10-20. http://standards.ieee.org/getieee802/download/802.11g-2003.pdf. Retrieved 2007-09-24.
^ http://download.wcvirtual.com/reference/802%20Channel%20Freq%20Mappings.pdf
^ "Official IEEE 802.11 working group project timelines". Sept. 19, 2009. http://grouper.ieee.org/groups/802/11/Reports/802.11_Timelines.htm. Retrieved 2009-10-09.
^ "Wi-Fi CERTIFIED n: Longer-Range, Faster-Throughput, Multimedia-Grade Wi-Fi® Networks" (registration required). Wi-Fi Alliance. September 2009. http://www.wi-fi.org/register.php?file=wp_Wi-Fi_CERTIFIED_n_Industry.pdf.
^ a b "802.11n Delivers Better Range". Wi-Fi Planet. 2007-05-31. http://www.wi-fiplanet.com/tutorials/article.php/3680781.
v
d
e
IEEE Standards
Current
488
754-2008 (Revision)
829
830
1003
1014-1987
1016
1076
1149.1
1164
1219
1233
1275
1284
1355
1364
1394
1451
1471
1516
1541-2002
1547
1584
1588
1596
1603
1613
1667
1675-2008
1685
1801
1900
1901
1902
11073
12207
802 series
802
.1 (p, Q, Qat, Qay, X, ad, AE, ag, ah, ak, aq)
.2
.3
.4
.5
.6
.7
.8
.9
.10
.11 (a b d e f g h i j k n p r s u v w y ac ad)
.12
.15
.15.4
.15.4a
.16
.18
.20
.21
.22
Proposed
P1363
P1619
P1823
P2030
Superseded
754-1985
854-1987
See also: IEEE Standards Association · Category:IEEE standards
Retrieved from "http://en.wikipedia.org/w/index.php?title=IEEE_802.11g-2003&oldid=457058077"
Categories: IEEE 802.11Hidden categories: Articles needing additional references from October 2007All articles needing additional referencesAll articles with unsourced statementsArticles with unsourced statements from January 2011Articles with unsourced statements from September 2009Articles containing potentially dated statements from 2009All articles containing potentially dated statements
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Tags:802.11n,488,754-2008,Revision,829,830,1003,1014-1987,1016,1076,1149.1,1164,1219,1233,1275,1284,1355,1364,1394,1451,1471,1516,1541-2002,1547,1584,1588,1596,1603,1613, | |
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