How Wireless Networking Works
The wireless network adapter you use to connect a PC to your
wireless network transmits data by radio waves. But unlike an FM radio
transmitter, your wireless networking equipment sends a signal that can only be
picked up for about 300 feet if there are no obstructions (and this kind of
performance is usually achieved outside only).
As with wired networking technology, such as Ethernet, data is
transmitted over a wireless network in pieces, called data packets. Each network
adapter has its own unique serial number, called a MAC (media access control) address. You can see the MAC
address of your wireless network adapter, as it's usually printed on the
underside of the adapter. The data packet contains the data being sent as well
as the address of the sender and recipient.
Wi-Fi (802.11b) wireless networks, as well as 802.11g
equipment, communicate over the unlicensed 2.4-GHz radio band. They share the
band with other home electronics, including cordless phones and microwaves.
Wi-Fi5 (or 802.11a) wireless networks use the less crowded 5GHz
band, and therefore are less affected by home electronics. While operating at up
to five times faster than Wi-Fi (802.11b) equipment, the hardware looks just the
same (Figure 2.6).
Until newer technologies such as Bluetooth (see sidebar) become
more prevalent, wireless networking will mean setting up a Wi-Fi system in most
home applications.
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Many PDAs, cell phones, and laptops can transmit data at very
high frequencies using beams of infrared light. Devices that use an infrared
wireless technology called IrDA (Infrared Data Association) can communicate with
each other. You could print a document from a laptop to a printer, for instance,
or transmit (beam) contact information from one PDA to another. IrDA is a
line-of-sight technology, which means that the devices much be lined up in a
straight line to communicate.
Bluetooth is another technology used to transfer data
wirelessly. Bluetooth is found in PDAs and cell phones and can be used to
transfer data to laptop and desktop computers and printers. Like 802.11b and
HomeRF networking equipment, Bluetooth operates in the 2.4 GHz band, does not
require a line of sight between components, and can pass through walls.
Bluetooth technology is sometimes referred to as a personal
area network (PAN). The technology has a more limited range (about 10 meters)
and less speed (720 kilobits per second) than wireless LAN equipment, such as
802.11b. |
Wireless network adapters can communicate directly with each
other. Each network adapter acts as a transmitter and receiver, and data is
broadcast in a cell. As the cells interlock, the network's range expands. A
wireless network in which the network adapters communicate directly with each
other is called a peer-to-peer network, or is
said to be working in ad-hoc mode. Wireless
networks can also work in infrastructure mode,
which requires the use of a hardware device that communicates with each network
adapter, called an access point (Figure
2.7).
Once your wireless networking equipment is set up, you can
share data and peripherals just as you would over a wired network.
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