MCSA/MCSE Self-Paced Training Kit (Exam 70-270): Installing ...

Lesson 3 Configuring Wireless Connections
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■ 802.11a 802.11a was developed around the same time as 802.11b, but 802.11b was
adopted by hardware manufacturers much faster than 802.11a. As a result, most manufacturers
did not start providing wireless devices using 802.11a until 2003. 802.11a
boasts a data transfer rate of 54 Mbps and operates in the 5.8 GHz radio frequency.
802.11a also provides greater resistance to electrical interference than 802.11b.
Advantages of 802.11a are that it provides the highest speed of the available
standards and also supports more simultaneous users in the same area than 802.11b.
Disadvantages are that 802.11a devices have the highest cost and a shorter range than
other standards. Also, 802.11a devices are not compatible with 802.11b devices.
■ 802.11g The development of 802.11g was finalized in 2002. 802.11g supports
data transfer rates up to 54 Mbps and operated in the 2.4 GHz radio frequency.
802.11g devices are compatible with 802.11b devices, but that compatibility comes
at a price. If a network uses only 802.11g devices, all wireless devices can operate
at up to 54 Mbps. If a network has even a single 802.11b device, 802.11g devices
must operate in mixed mode, which lowers the data transfer for 802.11g devices
by about 30 percent.
Note Some manufacturers make hybrid devices that support both 802.11a and 802.11g,
and such devices can connect to networks using any of the three standards mentioned here.
Real World Rated Speeds
Although the standards covered in this lesson have rated speeds (up to 11 Mbps
for 802.11b and up to 54 Mbps for 802.11a and 802.11g), these are mostly theoretical
values. In practice, you will never actually get that kind of data transfer rate.
Typical throughput for 802.11b products, for example, tops out around 4–5 Mbps.
The 802.11g products have an actual capacity of about 20 Mbps, and 802.11a
products have a capacity of 22 Mbps. In addition, even these more realistic transfer
rates are often further limited in the real world by interference from electrical
devices and materials in building structures.
Introduction to Wireless Networking Architecture
The 802.11 standard defines a number of main architectural components. These components
include the following:
■ Station (STA) A station (STA) is a client device on a wireless network—typically
a computer that has a wireless network adapter installed.