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Phone Line & Power Line Networks
Wireless Networks
Although wired networks are the most popular they aren't
always the most convenient. When computers are spread far
and wide throughout your home, you may think twice about
stringing cable up the stairs or drilling holes through
walls. Wireless home network kits have entered the market
and come in three different flavors: telephone lines, AC
power wiring or radio waves.
Phone Line Networks
If all your computers are located within easy distance of a
phone jack then a phone line network may be a good choice.
Though this technology is called "wireless" it actually uses
your home's internal phone wiring to connect one computer to
another. Most phone line networks require that all computers
be connected to the same phone line. A few manufacturers
have hardware that allows you to connect computers on two
different lines within the same home.
A phone line can carry multiple signals at different a
frequency which is why you can talk on the phone and still
use a DSL modem for internet access. Network traffic over
phone lines use frequencies higher than DSL or voice bands.
The industry standard for this technology is set by the
HomePNA (Phoneline Networking Alliance). The HomePNA 1.0
standard transfers at a maximum of 1 Mbps while version 2.0
transfers at 10 Mbps, supporting up to 150 m (500 ft) of
wiring between devices. Nearly all homes can use HomePNA 1.0
networks, but low-quality wiring in older homes may
interfere with version 2.0 networks.
Interfaces
There are several ways to connect your computer to a phone
line network: parallel port, USB, NIC or PC Card. As long as
all your network hardware is HomePNA compatible, you can mix
and match within a network. So you can have an older
computer with a parallel port adapter and a newer one with
an Ethernet adapter. HomePNA products are widely available
and supported by several different manufacturers.
Performance
In real life, it's unlikely you'll see the maximum transfer
rates quoted by the HomePNA. Even HomePNA 2.0 networks are
not as fast as a traditional 10 Mbps Ethernet. Depending on
your computer, the interface you select and the wiring in
your house, performance ranges from 20-70% of the rated
speed. Generally, PCI adapters are faster than USB and
parallel adapters.
Price
The least expensive option is an internal PCI card which
starts around $60 for a 1 Mbps model and $80 to $100 for a
10 Mbps card. USB adapters are slightly more expensive
beginning at $100. You can usually save some money by
purchasing a kit with two adapters. When you buy a network
kit you normally get drivers, software, internet sharing
utilities and a manual --removing a lot of the hassle from
installation.
Power Line Networks
Since power outlets are more widespread in a home than phone
jacks, a network that makes use of electrical wiring could
be more practical. Power line networks send data signals
through your existing AC power lines. The problem is that
data transmission uses the same frequency as household
appliances. Consequently, power lines suffer from a lot of
noise and interference which can make power line networks
unstable and unreliable. This is especially true if your
house has old wiring or you operate major appliances while
networking.
To date, there is only a handful of network products that
uses power lines. Kits with two adapters start at about
$200. The set-up is straightforward, but the maximum
transfer speed is only 340 Kbps and performance can degrade
if your drier or dishwasher is running at the same time.
Like the HomePNA, there is a HomePlug Powerline Alliance
composed of some of the biggest names in networking. They
are developing standards for a second generation of power
line network products with 10 Mbps transfer rates and
increased reliability.
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