Wireless Home Networking - Index of

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Part II: Making Plans
radio waves from each AP can interfere with the other. The same is true
if you live in a close packed neighborhood in which a lot of people have
APs for their home networks. Check out the following subsection for
more information regarding this phenomenon.
Wireless interference in the home
Probably the single biggest performance killer in
your wireless home network is interference in the
home. The Federal Communications Commission
(FCC) set aside certain unlicensed frequencies
that could be used for low-power wireless applications.
In specific frequency bands, manufacturers
can make (and you can use) equipment
that doesn’t require a license from the FCC for the
user to operate. This is different from, for example,
buying a 50,000-watt radio transmitter and
blasting it over your favorite FM radio frequency
band, which would be a major no-no because
those bands are licensed for certain power
levels.
As a result, all sorts of companies have created
products (including cordless phones, wireless
radio frequency [RF] remote controls, wireless
speakers, TV set extenders, and walkie-talkies)
that make use of these frequency bands. If you
have lots of wireless devices already in your
home, they may use some of the same frequency
bands as your wireless home network.
Another form of wireless interference comes
from devices that emit energy in the same
bands, such as microwave ovens. If you have
a cordless phone with its base station near a
microwave and you notice that the voice quality
degrades every time you use the microwave,
that’s because the micro (radio) waves are in
the same radiation band as your cordless
phone. Motors, refrigerators, and other home
consumer devices do the same thing.
What’s the answer? The good news is that you
can deal with almost all these by knowing what
to look for and being smart about where you
place your equipment. If your access point is in
the back office and you want to frequently work
in the living room with your laptop — but your
kitchen is in the middle — you may want to look
at adding a second access point in the living
room and linking it with the office via any of a
number of alternative connections options
(which we talk about in Chapter 3) that are
immune to the problems we mention here.
Remember these specific things to look for
when shopping. You see cordless phones operating
primarily in the 900 MHz, 2.4 GHz, and 5
GHz frequencies. The 900 MHz phones pose no
problems — but are also almost impossible to
find these days — and the 2.4 GHz and 5 GHz
phones interfere with your wireless network
signals (in the 802.11b/g and 802.11a frequency
ranges, respectively). Just know that cordless
phones and wireless home networks really
don’t like each other much. You can find cordless
phones that are designed not to interfere
with your wireless network. These phones are
usually labeled clearly that they are designed to
work within and around wireless networks. We
have tested a few, and while they do work much
better — your network connection does not
drop out when you answer the phone — they
still cause enough interference that your connection
will slow down a noticeable amount. In
Chapter 13, we talk about cordless phones that
carry your voice over your wireless network
and are part of the network instead of interfering
with it.