Wireless LANs - LAN Wiring - page 313

However, now you can use a wireless network system to connect computer
users to the Internet, or to an in-house network. This can be done at a comparable
cost of conventional wiring, in most cases, without conventional wiring's disadvan-
tages. Historic structures and architectural treasures can be preserved without for-
going the benefits of modern technology.
Another example of the value-oriented decision is convenience. You could eas-
ily connect to your corporate network at the conference table, in the cafeteria, or in
the lobby with wireless networking. In an educational setting, the instructor and the
students could carry their laptop computers into the classroom and immediately
connect to the campus network anywhere in the lecture hall.
Visitor registration desks, security stations, conference rooms, and cafeterias
can easily be connected in a moment to a wireless network. The flexibility and con-
venience is enormous, thus justifying the slight extra cost of wireless over wired con-
nections. And who wouldn't want to sit in a comfortable chair while fully connected
to the Internet? So, the complete value equation includes more than just cost. There
is a value to convenience and comfort.
Wireless Basics
Let's take a quick look at how wireless networking works. Wireless networking is
just a matter of sending and receiving data over radio frequencies. It works about the
same as how all radio devices work. The only differences are the modulation and the
actual frequency that is used (it's about 25 times the frequency of broadcast FM).
Wireless equipment is all around us. From pure audio-style radio, to broadcast
television, to cellular telephones, we use wireless technology every day. But to use
wireless networks, we need to understand a little more detail about how wireless
transmission and reception work.
Radio-Frequency Operation
Transmitting information through the air (or through space) is actually done by the
generation of electromagnetic (EM) fields—radio waves—and then “modulating”
content in the form of sound, coded pictures, or data.
These EM fields act a little like three-dimensional waves on a lake, because
they propagate in all directions, reflect off walls and other objects, and are affected
by the medium they pass through. Radio waves bounce off anything that is metal,
just like a water wave bouncing off a concrete object, like a dam. Sometimes, the
radio wave can penetrate an object, if it is not too thick or does not contain too
much metal. This is called attenuation , and saps the strength of the radio signal. If