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Photo:2
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| Description | |
| 2>
802.11b has a maximum raw data rate of 11 Mbit/s and uses the same CSMA/CA media access method defined in the original standard. Due to the CSMA/CA protocol overhead, in practice the maximum 802.11b throughput that an application can achieve is about 5.9 Mbit/s using TCP and 7.1 Mbit/s using UDP.
802.11b products appeared on the market in mid-1999, since 802.11b is a direct extension of the DSSS (Direct-sequence spread spectrum) modulation technique defined in the original standard. Technically, the 802.11b standard uses Complementary code keying (CCK) as its modulation technique. The dramatic increase in throughput of 802.11b (compared to the original standard) along with simultaneous substantial price reductions led to the rapid acceptance of 802.11b as the definitive wireless LAN technology.
802.11b devices suffer interference from other products operating in the 2.4 GHz band. Devices operating in the 2.4 GHz range include: microwave ovens, Bluetooth devices, baby monitors and cordless telephones. Interference issues and user density problems within the 2.4 GHz band have become a major concern and frustration for users.
[edit] Tags:Mbit/s,Ghz,802.11,Tcp,Microwave,Data Rate,Dsss,A,G,N,802,.1,P,Q,X,Ad,.4,.9,.11,D,E,F,H,I,J,K,R,S,U,V,W,Y,Ac, | |
| Range | |
| 2>
802.11b is used in a point-to-multipoint configuration, wherein an access point communicates via an omnidirectional antenna with one or more nomadic or mobile clients that are located in a coverage area around the access point. Typical indoor range is 30 m (100 ft) at 11 Mbit/s and 90 m (300 ft) at 1 Mbit/s. The overall bandwidth is dynamically demand shared across all the users on a channel. With high-gain external antennas, the protocol can also be used in fixed point-to-point arrangements, typically at ranges up to 8 kilometers (5.0 mi) although some report success at ranges up to 80–120 km (50–75 miles) where line of sight can be established. This is usually done in place of costly leased lines or very cumbersome microwave communications equipment. Designers of such installations who wish to remain within the law must however be careful about legal limitations on effective radiated power.[1]
802.11b cards can operate at 11 Mbit/s, but will scale back to 5.5, then 2, then 1 Mbit/s (also known as Adaptive Rate Selection), if signal quality becomes an issue.
[edit] Tags:Point-to-multipoint,Access Point,Line Of Sight,Leased Lines,Effective Radiated Power,Ag,.5, | |
| Channels and Frequencies | |
| 2>
802.11b/g channels in 2.4 GHz band
802.11b channel to frequency map [2]
Channel
Center Frequency
Frequency delta
Channel Width
Overlaps Channels
1
2.412 GHz
5 MHz
2.401–2.423 GHz
2
2
2.417 GHz
5 MHz
2.406–2.428 GHz
1,3
3
2.422 GHz
5 MHz
2.411–2.433 GHz
2,4
4
2.427 GHz
5 MHz
2.416–2.438 GHz
3,5
5
2.432 GHz
5 MHz
2.421–2.443 GHz
4,6
6
2.437 GHz
5 MHz
2.426–2.448 GHz
5,7
7
2.442 GHz
5 MHz
2.431–2.453 GHz
6,8
8
2.447 GHz
5 MHz
2.436–2.458 GHz
7,9
9
2.452 GHz
5 MHz
2.441–2.463 GHz
8,10
10
2.457 GHz
5 MHz
2.446–2.468 GHz
9,11
11
2.462 GHz
5 MHz
2.451–2.473 GHz
10,12
12
2.467 GHz
5 MHz
2.456–2.478 GHz
11,13
13
2.472 GHz
5 MHz
2.461–2.483 GHz
12
14
2.484 GHz
12 MHz
2.473–2.495 GHz
Note: Channel 14 is only allowed in Japan, Channels 12 & 13 are allowed in most parts of the world, except the USA, where only Channels 1 to 11 are legal to use. More information can be found in the List of WLAN channels.
[edit] Tags:List Of Wlan Channels, | |
| See also | |
| 2>
IEEE 802.11
IEEE 802.11g-2003
Wi-Fi
List of WLAN channels
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[3]
Freq.
(GHz)
Bandwidth
(MHz)
Data rate per stream
(Mbit/s)[4]
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[5]
40
15, 30, 45, 60, 90, 120, 135, 150[B]
70
230
250
820[5]
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:Ieee 802.11,Wi-fi,Ieee,802.11g,Ieee 802.11g-2003,Fcc,Guard Interval,Mimo,—,Fhss,Ofdm,Ac (draft),Standards,.2,.3, | |
| References | |
| 2>
^ "Code of Federal Regulations, Title 47-Telecommunications, Chapter I-Federal Communications Commission, Part 15-Radio Frequency Devices, Section 15.247". 2006-10-01. http://a257.g.akamaitech.net/7/257/2422/13nov20061500/edocket.access.gpo.gov/cfr_2006/octqtr/pdf/47cfr15.247.pdf. Retrieved 2008-01-09.
^ 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.
"802.11b-1999 Higher Speed Physical Layer Extension in the 2.4 GHz band" (pdf). 1999-02-11. http://standards.ieee.org/getieee802/download/802.11b-1999.pdf. Retrieved 2007-09-24.
"Corrigenda to 802.11b-1999 Higher Speed Physical Layer Extension in the 2.4 GHz band" (pdf). 2002-01-30. http://standards.ieee.org/getieee802/download/802.11b-1999_Cor1-2001.pdf. Retrieved 2007-09-24.
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_802.11b-1999&oldid=467286822"
Categories: IEEE 802.11Hidden categories: All articles with unsourced statementsArticles 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, | |
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