| IEEE Std 802.11 Wireless LAN Medium Access Control and Physical layer specifications |
WLAN is a local area network that uses high frequency radio waves rather than wires as transmission medium.
802.11, developed starting from 1997 by a Working Group of the Institute of Electrical and Electronics Engineers (IEEE), is the base standard for the wireless LAN medium access control and physical layer specifications.
The 802.11 standard family includes 802.11a and 802.11b, ratified in September 1999, and 802.11g ratified in June 2003. |
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802.11b uses Complementary Code Keying (CCK) modulation to transmit data signals and operates in the 2.4Ghz unlicensed ISM (industrial, scientific and medical radio spectrum) band.
The standard includes 4 data rates: 1, 2, 5.5, 11Mbps. It is also known as Wi-Fi, a brand name established by the Wireless Ethernet Compatibility Alliance (WECA), now called Wi-fi Alliance.
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802.11a uses an Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme to transmit data signals and operates in the 5GHz unlicensed band.
The standards includes eight different data rates: 6, 9, 12, 18, 24, 36, 48, 54Mbps.
Clients and access points supporting 802.11a appeared towards the end of 2001.
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802.11g uses OFDM (same modulation adopted in 802.11a std) and CCK as mandatory modulation schema and operates in the 2.4Ghz unlicensed ISM band.
802.11g provides different data rates according to the modulation (CCK: 1, 2, 5.5, 11Mbps or OFDM: 6, 9, 12, 18, 24, 36, 48, 54Mbps).
802.11g takes some of 802.11a technology improvements ensuring the backward compatibility with 802.11b. |
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802.11b |
802.11a |
802.11g |
| Standard Ratified |
September 1999 |
September 1999 |
June 2003 |
Frequency of
Operations |
2.4GHZ |
5GHz |
2.4GHz |
Non Overlapping
Channels |
3 |
12 |
3 |
| Modulation Type |
CCK |
OFDM |
CCK and OFDM |
| Data Rates (Mbps) |
1,2,5.5,11 |
6,9,12,18,
24,36,48,54 |
CCK: 1,2,5.5,11
OFDM: 6,9,12, 18,24, 36,48,54 |
| Range (typical) |
100-150 feet indoor |
25-27 feet indoor |
100-150 feet indoor |
| Compatibility |
11g |
none |
11b |
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Related Information |
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