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
(mentioned earlier).
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. Because of this innate vulnerability to surrounding
environmental factors, it’s pretty apparent that wireless will never offer us the same
robustness as wired networks can, but that still doesn’t mean we’re not going to run wireless.
Believe me, we definitely will!
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 your unique situation.
Also important to note is that the 802.11 specifications were developed so that there would
be no licensing required in most countries—to give the user the freedom to install and operate
without any licensing or operating fees. This means any manufacturer can create products and
sell them at a local computer store or wherever. It also means that all our computers should
be able to communicate wirelessly without configuring much, if anything at all.
Various agencies have been around for a long time to help govern the use of wireless devices,
frequencies, standards, and how the frequency spectrums are used. Table 9.1 shows the current
agencies that help create, maintain, and even enforce wireless standards worldwide.