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Introducing Wireless Technology
Transmitting a signal using the typical 802.11 specifications works a lot like it does with a basic
Ethernet hub: They’re both two-way forms of communication, and they both use the same frequency
to both transmit and receive, often referred to as half-duplex and mentioned in the introduction
to this chapter. Wireless LANs (WLANs) use radio frequencies (RFs) that are radiated
into the air from an antenna that creates radio waves. These waves can be absorbed, refracted,
or reflected by walls, water, and metal surfaces, resulting in low signal strength. So because of
this innate vulnerability to surrounding environmental factors, it’s pretty apparent that wireless
will never offer us the same robustness as a wired network can, but that still doesn’t mean we’re
not going to run wireless.
We can increase the transmitting power and gain a greater transmitting distance, but doing
so can create some nasty distortion, so it has to be done carefully. By using higher frequencies,
we can attain higher data rates, but this is, unfortunately, at the cost of decreased transmitting
distances. And if we use lower frequencies, we get to transmit greater distances but at lower
data rates. This should make it pretty clear to you that understanding all the various types
of WLANs you can implement is imperative to creating the LAN solution that best meets the
specific requirements of the unique situation you’re dealing with.
Also important to note is the fact that the 802.11 specifications were developed so that
there would be no licensing required in most countries—to ensure the user the freedom to
install and operate without any licensing or operating fees. This means that any manufacturer
can create products and sell them at a local computer store or wherever. It also means that we
should all be able to get our computers to communicate wirelessly without configuring much. Various agencies have been around for a very long time to help govern the use of wireless
devices, frequencies, standards, and how the frequency spectrums are used.
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