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Wi-Fi was originally a brand licensed by the Wi-Fi Alliance to describe the embedded technology of wireless local area networks (WLAN) based on the IEEE 802.11 standard. As of 2007, common use of the term Wi-Fi has broadened to describe the generic wireless interface of mobile computing devices. IEEE 802.11, commonly known by the brand Wi-Fi, denotes a set of Wireless LAN standards developed by working group 11 of the IEEE LAN/MAN Standards Committee (IEEE 802). Wi-Fi technologies have gone through several generations since their inception in 1997. Wi-Fi is supported to different extents under Microsoft Windows, Apple Mac OS and open source Unix and Linux operating systems.

If you want to understand wireless networking at its simplest level, think about a pair of $5 walkie-talkies that you might purchase at Wal-Mart. These are small radios that can transmit and receive radio signals. Recall, when you talk into a Walkie-Talkie, your voice is picked up by a microphone, encoded onto a radio frequency and transmitted with the antenna. Another walkie-talkie can receive the transmission with its antenna, decode your voice from the radio signal and drive a speaker.

Simple walkie-talkies like this transmit at a signal strength of about 0.25 watts, and they can transmit about 500 to 1,000 feet. We wish to consider how these walkie-talkies can be used to communicate between the two computers. In order to do this, we require, Each computer is equipped with a walkie-talkie We would give each computer a way to set whether it wants to transmit or receive. And we would give the computer a way to turn its binary 1s and 0s into two different beeps that the walkie-talkie could transmit and receive and convert back and forth between beeps and 1s/0s. This would actually work. The only problem would be that the data rate would be very slow. A $5 walkie-talkie is designed to handle the human voice (and it's a pretty scratchy rendition at that), so you would not be able to send very much data this way. Maybe 1,000 bits per second. Another problem: the walkie-talkies could not be used to connect to the internet.

The radios used in WiFi are not so different from the radios used in $5 walkie-talkies. They have the ability to transmit and receive, they have the ability to convert 1s and 0s into radio waves and then back into 1s and 0s. There are major differences, of course

They transmit at frequencies of 2.4 GHz or 5GHz. 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: 802.11b 802.11b was the first version to reach the marketplace. It's the slowest and least expensive standard, and 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 complimentary code keying (CCK) coding. 802.11g 802.11g also transmits at 2.4 GHz, but it's a lot faster than 802.11b -- it can handle up to 54 megabits of data per second. 802.11g is faster because it uses orthogonal frequency-division multiplexing (OFDM), a more efficient coding technique. 802.11a 802.11a transmits at 5GHz and can move up to 54 megabits of data per second. It also and uses OFDM coding. Newer standards, like 802.11n, can be even faster than 802.11g. However, the 802.11n standard isn't yet final. 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 and virtually invisible, and it's fairly reliable. If the router fails or if too many people try to use high-bandwidth applications at the same time, however, users can experience interference or lose their connections.