Wireless networking is one of several ways to connect the
computers in your home. It creates a network by sending
radio-frequency signals between your computers to share
Please be sure to read the companion article How Home
Networking Works, which provides information about
configuring your computers, routers and firewalls, Ethernet
networking and sharing an Internet connection. There are also
companion articles about power-line
networking and phone-line
networking. By the time you finish this series of
articles, you will be able to choose a network technology that
suits your needs and then configure the whole thing!
In this edition of HowStuffWorks,
we'll talk about wireless networking and the technology used
to make it happen. We'll also discuss the advantages and
disadvantages of using a wireless network.
Wireless Networking Wireless networking
technologies take the concept of "no new wires" one step
further. In a wireless network, all of the computers in your
home broadcast their information to one another using radio
signals. This can make networking extremely easy, especially
if you have computers all over your house. It also makes it a
whole lot simpler to move computers around. For example, a laptop with
a wireless network card is completely portable throughout the
Power-line Networking Works, we discussed peer-to-peer and
client/server networks. In wireless networking, a peer-to-peer
(or point-to-point) wireless network means that each
computer can communicate directly with every other computer on
the network. But some wireless networks are client/server.
They have an access point, which is a wired controller
that receives and transmits data to the wireless adapters
installed in each computer.
There are four types of wireless networks, ranging from
slow and inexpensive to fast and expensive:
(Infrared Data Association) is a standard for devices to
communicate using infrared light pulses. This is how remote
controls operate, and the fact that all remotes use this
standard allows a remote from one manufacturer to control a
device from another manufacturer. Since IrDA devices use
infrared light, they depend on being in direct line of sight
with each other. Although you can purchase and install an
IrDA-based network capable of transmitting data at speeds up
to 4 megabits per second (Mbps), the requirement for line of
sight means that you would need an access point in each room,
limiting the usefulness of an IrDA network in a typical home
Before we talk about SWAP and Wi-Fi, we need to understand
the original standard that both of these new specifications
are based on. The original Institute
of Electrical and Electronics Engineers wireless-Ethernet
specification, known as IEEE 802.11, designated two
ways of communicating between devices and allowed for speeds
up to 2 Mbps. Both communication methods, direct-sequence
spread spectrum (DSSS) and frequency-hopping spread
spectrum (FHSS), use the frequency-shift keying (FSK)
technology we discussed in power-line networking. Also, both
are based on spread-spectrum radio waves in the
2.4-gigahertz (GHz) range.
spectrum simply means that data is sent in small pieces
over a number of the discrete frequencies available for use at
any time in the specified range. Devices using direct-sequence
spread spectrum (DSSS) communicate by splitting each byte of
data into several parts and sending them concurrently on
different frequencies. DSSS uses a lot of the available
bandwidth, about 22 megahertz (MHz). Devices using
frequency-hopping spread spectrum (FHSS) send a short burst of
data, shift frequencies (hop) and then send another short
burst. Since the FHSS devices that are communicating agree on
which frequencies to hop to, and use each frequency for a
brief period of time (less than 400 milliseconds) before
moving on, several independent FHSS networks can exist in the
same physical area without interfering with each other. Also,
due to FCC
restrictions, as well as the fact that FHSS devices generally
send data on just two to four frequencies simultaneously, they
only use 1 MHz or less of the available bandwidth. Because
they use any given frequency for such a short time, FHSS
devices are less prone to interference than DSSS devices. But
DSSS is capable of much greater speed than FHSS since these
devices can send a lot more data at the same time. Currently,
FHSS-based devices are easier and cheaper to produce, which
has led the HomeRF group to adopt FHSS as the method of
communication for their products.
HomeRF and SWAP HomeRF
(RF stands for radio frequency) is an alliance of businesses
that have developed a standard called Shared Wireless
Access Protocol (SWAP). A sort of hybrid standard, SWAP
includes six voice channels based on the Digital Enhanced
Cordless Telecommunications (DECT) standard and the 802.11
wireless-Ethernet specification for data. SWAP devices make 50
hops per second and transmit at 1 Mbps. Depending on the
manufacturer, some of these can step up to 2 Mbps if there is
very little interference in their operational area.
Here are the advantages of SWAP:
It's inexpensive ($70 to $200 per device).
It's easy to install.
It requires no additional wires.
It has no access point.
It uses six full-duplex voice channels and one data
It allows up to 127 devices per network.
It allows multiple networks in the same location.
You can use encryption to make your data secure.
Here are the disadvantages of SWAP:
It's not very fast (normally 1 Mbps).
It has a limited range (75 to 125 ft / 23 to 38 m).
It's not compatible with FHSS devices.
Physical obstructions (walls, large metal objects) can
interfere with communication.
It's difficult to integrate into existing wired
This wireless PCI card is inserted inside
your computer to build a wireless
The actual wireless transceiver, with a small, integrated
antenna, is built into an ISA, PCI or PCMCIA card. If you have
a laptop computer, the PCMCIA card plugs directly into one of
the PCMCIA slots. For desktop computers, you will either need
a dedicated ISA or PCI HomeRF card, or a PCMCIA card with a
special adapter. ISA and PCI adapters are inserted inside the
computer and have a slot that is accessible from the back of
your computer so you can plug in the PCMCIA card. USB adapters
are external devices that you plug the PCMCIA card into and
then connect to a USB port on the computer. Some of the HomeRF
manufacturers sell kits that include the appropriate adapter
along with the PCMCIA cards and installation software.
Currently, because of the need to use dedicated cards, only
computers can participate in a SWAP network. Printers and
other peripheral devices need to be physically connected to a
computer and shared as a resource by that computer.
In most cases, SWAP-based networks are point-to-point. Some
manufacturers do offer access points as an option to increase
the effective range of the wireless network, but they are not
required equipment. Mainly because of this lack of an access
point, HomeRF networks are significantly cheaper than the
other viable wireless network, WECA's Wi-Fi. But the tradeoffs
for cost are speed and distance. If you can set up a wired
network using HomePNA or traditional Ethernet, you will get 10
to 100 times the speed for the same amount of money or less.
However, unless you plan to send large amounts of data (like
video) back and forth, SWAP speed is probably adequate for
most home use, and the freedom of no wires can be quite
appealing. Just remember that this is still a developing
WECA and Wi-Fi The Wireless
Ethernet Compatibility Alliance (WECA) has gone in a
completely different direction from HomeRF. Targeted more at
office use than home networks, Wi-Fi (for "wireless
fidelity", like Hi-Fi for "high fidelity" in audio equipment)
is essentially a seal of approval that says the manufacturer's
product is compliant with a variation of the IEEE 802.11
specification known as IEEE 802.11b. This specification
drops FHSS and focuses on DSSS because of the higher data rate
it can attain. Under 802.11b, devices communicate at a speed
of 11 Mbps whenever possible. If signal strength or
interference is disrupting data, the devices will drop back to
5.5 Mbps, then 2 Mbps and finally down to 1 Mbps. Though it
may occasionally slow down, this keeps the network stable and
Photo courtesy Nexland The ISB Wavebase by Nexland allows you to
connect wireless devices to your fast Internet
Here are the advantages of Wi-Fi:
It's fast (11 Mbps).
It has a long range (1,000 ft / 305 m in open areas, 250
to 400 ft / 76 to 122 m in closed areas)
It's easily integrated into existing wired-Ethernet
It's compatible with original 802.11 DSSS devices.
Here are the disadvantages:
It can be difficult to set up.
Speed can fluctuate significantly.
Ethernet speeds without the wires, but you pay for it. There
are Wi-Fi compatible PC cards that operate in peer-to-peer
mode, but Wi-Fi usually requires access points, which range in
cost from about $300 to $1,400. Most access points have an
integrated Ethernet controller to connect to an existing
wired-Ethernet network. It also has an omni-directional
antenna to receive the data transmitted by the wireless
sells an inexpensive ($299 list) and easy-to-configure access
point called Airport. Airport has to be connected to an Apple
computer (iMac, PowerMac, iBook), but it will accept signals
from any 802.11b-compatible wireless-network card, whether
it's PC or Mac-based.
Like HomeRF systems, the majority of Wi-Fi wireless
transceivers available are in PCMCIA card form. But some
manufacturers do offer PCI or ISA format cards, not just
adapters. The cost per card ranges from $99 to more than $300.
Because these products are not targeted at the home market,
they are not typically sold in "do-it-yourself" kits. Instead,
everything is a la carte, allowing customers to build a
system that exactly meets their needs.
This is the base unit of a wireless system
used to connect workers with
At the HowStuffWorks
offices, we have installed the 3Com
Airconnect wireless system with great results. Several of our
staff members now freely roam about the workplace with their
laptops constantly connected to the network. We invested about
$1,400 for the access point and three PCMCIA cards. That's not
a bad investment to foster a dynamic work environment, but is
certainly on the expensive side for most home networks.
If you are a Mac owner, setting up a Wi-Fi-compatible
network is easy, and reasonable in terms of cost. Otherwise,
this is an expensive undertaking that requires careful
consideration of your needs. In fact, you can buy an
inexpensive Apple computer and an Airport access point for
close to the amount of money you would invest in most other
access points currently available.
There are two other networking technologies that we will
discuss: phone-line and power-line networks. Click on the
title to go to one of these articles for more information, or
proceed to A Word
About Macs or The
Future of Home Networking.