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Radio Wave Networks
The true home wireless LAN (WLAN) uses low frequency radio
waves to transmit data between computers. Each computer has
an adapter that sends and receives radio signals. Since
radio frequencies can penetrate most indoor walls and
obstacles, a line-of-sight between computers isn't required.
Just as radio reception degrades the farther you are from
the transmitter so network speeds slow the farther you are
from the other networked computers. Network performance can
also be affected by the type of construction in your home.
For example, it's harder for radio waves to penetrate
concrete than drywall and the more walls separating your
computers, the slower the network.
Wireless Protocols
At the moment there are two wireless protocols vying for
prominence. HomeRF is the less expensive of the two and can
transfer data at 1.6 Mbps, allowing computers to be up to 50
m (150 ft) apart. HomeRF provides adequate performance for
most networking tasks but is under-powered when it comes to
playing raw CD audio across a network or streaming any video
content. Fortunately a 10 Mbps version of HomeRF is now
available and worth considering.
The 802.11b protocol (Wi-Fi) is gaining in popularity and
support as prices come down though it is still an expensive
option for the home. Wi-Fi requires more equipment than
HomeRF which contributes to the cost. However, at 11 Mbps
with up to 500m (1600 feet) between devices it's powerful
enough for full-motion digital video. It also supports other
computing devices such as PDA's.
For households with Macs, Wi-Fi is a good choice because
recent Apple models can be fitted with an Airport card, an
inexpensive option that uses the 802.11b standard. Wi-Fi is
also being adopted for wireless connectivity in public
places, college campuses and the workplace, using the same
network adapter one would use in the home. Microwave ovens
and 2.4GHz portable phones are a potential source of
interference with 802.11b networks though often problems can
be fixed by moving devices.
Interface
Wireless adapters come in several forms including USB,
parallel port, ISA, PCI and PC Card. External parallel port
and USB adapters have built in radio antennae and plug into
your computer. Internal network cards either have antennae
attached to them directly or by a cord that plugs into the
card. PC Card adapters with attached antennae are available
for laptops.
Access Points
An Access Point is a transmitter/receiver that can connect
an 802.11b network to a wired LAN. Access points can also be
used to increase range by acting as a relay point,
retransmitting a signal from one wireless network to the
next. The average home should be small enough to do without
access points which are geared more to campus or corporate
settings with a price tag between $300-1000.
Performance
Since numerous factors influence wireless transmission
you'll rarely approach the maximum networking speeds set out
by the various wireless protocols. Data transfer can vary
between 30-60% of the stated maximum depending on adapter
interface, distance between computers and obstacles in the
way. HomeRF is slower than Ethernet, usually under 1 Mbps.
Wi-Fi wireless LANs transmit in the 3.5 to 4.5 Mbps range.
Price
Wireless networking offers the greatest flexibility and
mobility, but at a price. Kits vary in cost depending on the
interface and protocol you choose. The least expensive kits
(2 adapters) are based on HomeRF with prices in the range of
$150-300. Wi-Fi kits are $300 plus.
Interoperability
The proliferation of wireless standards means that
interoperability is a big issue. In theory, products from
different manufacturers that adhere to the same protocol and
display the logo of one the organizations (like HomeRF or
WiFi) should work together, but there's a potential for
headaches. Although various organizations are trying to make
the different wireless standards compatible, you should
avoid mixing products that use different protocols.
Hybrid Networks
If you have both Macs and PCs, choosing a wireless network
can be a little more challenging. Intelogis' power line kits
do not support Macs, but some HomePNA products do. Depending
on the type of Mac you have you can use PCI, USB or
Ethernet-to-phone-line adapters to create a phone line
network with your Mac.
True wireless networks will also support cross-platform
networks, but most products are for one platform only. For
example, Apple's AirPort products are Mac only, and the
majority of wireless home network kits are PC only. There
are a few kits that will work with PC and Linux. At the
moment no manufacturer makes a PCI or USB product that will
support both Mac and PC, but 3Com has stated it plans to add
Mac support to its wireless products in the future.
If you're really determined and have deep pockets, you can
buy an Apple AirPort base station or an Orinoco (formerly
WaveLan) access point; both follow the IEEE 802.11b
protocol. Both types of access points can connect to Macs
and PC's with any 802.11 b compliant wireless adapter. You
can even use the AirPort base station in an all PC network.
If you have a laptop, Farallon makes a PC Card adapter that
will connect a Mac or PC laptop to an 802.11b compliant
access point. Two laptops with this PC Card can network to
each other without an access point.
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