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