Wireless
Networking
Wireless
Networking is one of several ways to connect the computers in your
home or office. Wireless Networking creates a network by sending
radio-frequency signals between your computers to share information.
At the end of
2000, according to International Data Corp. (IDC), about half of all
U.S. households had a computer, and more than 20
million of those had more than one computer. In fact, market
research shows that current PC owners are buying most of the new
computers. This means that multi-computer households are becoming
pretty common. If you
are one these multiple-PC owners, you have probably thought about
how great it would be if your computers could talk to each other
using Wireless Networking. Because with your computers connected,
you could:
- Share a
single printer between computers
- Use a single
Internet connection
- Share files
such as images, spreadsheets and documents
- Play games
that allow multiple users at different computers
- Send the
output of a device like a DVD player or Webcam to your other
computer(s)
And that is
possible using the benefits of Wireless
Networking.
Wireless
Networking technologies take the concept of "no new wires" one step
further. In Wireless Networking, 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
house!
There are four
types of Wireless Networking, ranging from slow and inexpensive to
fast and expensive:
- Bluetooth
- IrDA
- HomeRF
(SWAP)
- WECA
(Wi-Fi)
Let’s see them
more clearly by better explaination of these terms in Wireless
Networking.
Bluetooth is
not widely available yet and is not expected to replace the need for
high-speed data networks between
computers.
IrDA (Infrared
Data Association) Wireless Networking 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
layout.
Spread 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.
