Wireless Home Networking - Index of

Chapter 5: Choosing Wireless Home Networking Equipment
We talk much more about security in Chapter 9. We encourage you to read
that chapter so that you can be well prepared when you’re ready to install
your equipment.
Range and Coverage Issues
An AP’s functional range (the maximum distance from the access point at
which a device on the wireless network can receive a useable signal) and
coverage (the breadth of areas in your home where you have an adequate
radio signal) are important criteria when selecting an AP. Wi-Fi equipment is
designed to have a range of hundreds of meters when used outdoors without
any obstructions between the two radios. Coverage depends on the type of
antenna used.
Just like it’s hard to know how good a book is until you read it, it’s hard to
know how good an AP is until you install it. Do your research before buying
an AP, and then hope that you make the right choice. Buying ten APs and
returning the nine you don’t want is simply impractical. (Well, maybe not
impractical, but rather rude.) The key range and coverage issues, such as
power output, antenna gain, or receive sensitivity (which we cover in
Chapter 2) aren’t well labeled on retail boxes. Nor are these issues truly comparable
among devices because of the same lack of consistent information.
Because many of these devices are manufactured using the same chipsets,
performance usually doesn’t vary extensively from one AP to another.
However, that is a broad generalization and some APs do perform badly. Our
advice: Read the reviews and be forewarned! Most reviews of APs and wireless
routers do extensive range and throughput (speed) testing — look at
sites such as CNET (www.cnet.com) or ZDNet (www.zdnet.com).
In Chapter 2, we talk about the differences between the 2.4 and 5 GHz frequency
bands that different Wi-Fi systems use (802.11b and g use 2.4 GHz,
802.11a uses 5 GHz, and 802.11n can use either). In that chapter we also talk
about the fact that higher frequencies (that is, 5 GHz compared to 2.4 GHz)
tend to have shorter ranges than lower frequencies (all things equal — which
they’re not in the case of 802.11n, more on that in a moment). In general, 2.4
GHz systems have a longer reach, but they also operate in a more crowded
set of frequencies and are therefore more prone to interference from other
systems (other Wi-Fi networks and other devices such as phones and
microwaves). In an urban environment, you may very well find that a 5 GHz
system has a better range simply due to this lack of interference.
The 802.11n systems on the market use multiple antennas and special techniques
to boost, or focus, the antenna power and greatly increase the range
of the AP versus a standard 802.11g model. Even when operating in the 5 GHz
frequency range, you should find that an 802.11n system has a range several
times greater than that of an 802.11g system.
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