In the simplest of terms, a wireless LAN (WLAN) does exactly what the name
implies. It provides all the features and benefits of traditional LAN
technologies such as Ethernet and Token Ring, but without the limitations of
wires or cables. Thus, WLANs redefine the way the industry views LANs.
Connectivity no longer implies attachment. Local areas are measured not in feet
or meters, but in miles or kilometers. An infrastructure need not be buried in
the ground or hidden behind walls. An infrastructure can be moved and changed
based on the needs of an organization.
A WLAN, just like a LAN, requires
a physical medium through which transmission signals pass. Instead of using
twisted-pair or fiber-optic cable, WLANs use infrared light (IR) or radio
frequencies (RFs). The use of RF is far more popular for its longer range,
higher bandwidth, and wider coverage. WLANs use the 2.4-gigahertz (GHz) and
5-GHz frequency bands. These portions of the RF spectrum are reserved in most
of the world for unlicensed devices. Wireless networking provides the freedom
and flexibility to operate within buildings and between buildings. Throughout
this course, the icons and symbols displayed in Figures
through
will be used to
document the wireless networking devices and infrastructure.