A wireless network uses radio
waves, just like cell phones, televisions and radios do.
In fact, communication across a wireless network is a
lot like two-way radio communication. This is how the
A computer's wireless
adapter translates data into a radio signal and
transmits it using an antenna.
A wireless router receives
the signal and decodes it. The router sends the
information to the Internet using a physical, wired
The process also works in
reverse, with the router receiving information from the
Internet, translating it into a radio signal and sending
it to the computer's wireless adapter.
The radios used for WiFi
communication are very similar to the radios used for
walkie-talkies, cell phones and other devices. They can
transmit and receive radio waves, and they can convert
1s and 0s into radio waves and convert the radio waves
back into 1s and 0s. But WiFi radios have a few notable
differences from other radios:
They transmit at frequencies of 2.4 GHz or 5 GHz.
This frequency is considerably higher than the
frequencies used for cell phones, walkie-talkies and
televisions. The higher frequency allows the signal
to carry more data.
They use 802.11 networking standards, which come in
several flavors: 802.11a transmits at 5 GHz and can
move up to 54 megabits of data per second. It also
uses orthogonal frequency-division multiplexing (OFDM),
a more efficient coding technique that splits that
radio signal into several sub-signals before they
reach a receiver. This greatly reduces interference.
802.11b is the slowest and least expensive standard.
For a while, its cost made it popular, but now it's
becoming less common as faster standards become less
expensive. 802.11b transmits in the 2.4 GHz
frequency band of the radio spectrum. It can handle
up to 11 megabits of data per second, and it uses
complementary code keying (CCK) modulation to
improve speeds. 802.11g transmits at 2.4 GHz like
802.11b, but it's a lot faster -- it can handle up
to 54 megabits of data per second. 802.11g is faster
because it uses the same OFDM coding as 802.11a.
802.11n is the newest standard that is widely
available. This standard significantly improves
speed and range. For instance, although 802.11g
theoretically moves 54 megabits of data per second,
it only achieves real-world speeds of about 24
megabits of data per second because of network
congestion. 802.11n, however, reportedly can achieve
speeds as high as 140 megabits per second. The
standard is currently in draft form -- the Institute
of Electrical and Electronics Engineers (IEEE) plans
to formally ratify 802.11n by the end of 2009.
Other 802.11 standards focus on specific
applications of wireless networks, like wide area
networks (WANs) inside vehicles or technology that
lets you move from one wireless network to another
WiFi radios can transmit on any of three frequency
bands. Or, they can "frequency hop" rapidly between
the different bands. Frequency hopping helps reduce
interference and lets multiple devices use the same
wireless connection simultaneously.
As long as they all have wireless adapters, several
devices can use one router to connect to the Internet.
This connection is convenient, virtually invisible and
fairly reliable; however, if the router fails or if too
many people try to use high-bandwidth applications at
the same time, users can experience interference or lose