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802.11 and Wi-Fi
[sources; in conjunction with Searchmobilecomputing.com]
802.11 is a family of specifications for
developed by a working group of the Institute of Electrical and Electronics Engineers
There are currently four specifications in the family: 802.11,
and
All four use the
protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for
path sharing.
The most recently approved standard, 802.11g, offers wireless transmission over
relatively short distances at up to 54
per second (Mbps) compared with the 11 megabits per second of the 802.11b standard.
Like 802.11b, 802.11g operates in the 2.4
range and is thus compatible with it.
The 802.11b standard - often called
- is
with 802.11. The
used in 802.11 has historically been phase-shift keying
The modulation method selected for 802.11b is known as complementary code keying (CCK),
which allows higher data speeds and is less susceptible to multipath-propagation interference.
The 802.11a specification applies to wireless
systems and is used in access
802.11a operates at radio frequencies between 5
and 6 GHz. It uses a modulation scheme known as orthogonal frequency-division
multiplexing
that makes possible data speeds as high as 54 Mbps, but most commonly, communications takes place at 6 Mbps, 12 Mbps, or 24 Mbps.
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