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 Post subject: What is WiFi
 Post Posted: Mon May 10, 2010 6:22 pm 
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Wi-Fi, which stands for wireless fidelity, in a play on the older term Hi-Fi, is a wireless networking technology used across the globe. Wi-Fi refers to any system that uses the 802.11 standard, which was developed by the Institute of Electrical and Electronics Engineers (IEEE) and released in 1997. The term Wi-Fi, which is alternatively spelled WiFi, Wi-fi, Wifi, or wifi, was pushed by the Wi-Fi Alliance, a trade group that pioneered commercialization of the technology.
Wi-Fi (pronounced /ˈwaɪfaɪ/) is a trademark of the Wi-Fi Alliance

A wireless network uses radio waves, such as mobile phones, televisions and radios. In fact, communication across a wireless network is a bit like two-way radio communications. Here’s what happens:

1. A computer on the wireless adapter translates data into a radio signal and transmits through an antenna.
2. A wireless router receives the signal and decodes. The router sends information to the Internet using a physical, wired Ethernet connection.This process also works in reverse, with the router receiving information from the Internet, translating it into a radio signal and send it to your wireless adapter. Radios used for WiFi communication are very similar to those used for walkie-talkie radios, cell phones and other devices. They can send and receive radio waves, and they can convert 1s and 0s into radio waves and convert the radio waves in 1 and 0 But WiFi radios have some notable differences from other radios:

* They transmit at frequencies of 2.4 GHz or 5 GHz. This frequency is much higher than the frequencies used for cellular phones, walkie-talkies and televisions. Increase the frequency of the signal can carry more data.
* They use 802.11 networking standards that are in several variants:
o 802.11a transmit at 5 GHz and up to 54 megabits of data per second. He also uses orthogonal frequency-division multiplexing (OFDM), a more efficient coding technique that splits the radio signal into several sub-signals before they reach a receiver. This reduces interference.
o 802.11b is the slowest and least expensive standard. For a time, has seen its costs, but it is now less common for a faster cheaper. 802.11b transmit in the frequency band 2.4 GHz radio spectrum use. It can handle up to 11 megabits of data per second, and using additional code before (CCK) to improve the speed of modulation.
o 802.11g transmit at 2.4 GHz like 802.11b, but it is much 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.
o The new 802.11n standard, which is widely available. This standard significantly improves speed and range. For instance, although 802.11g theoretically moves 54 megabits of data per second, making real-world speeds of around 24 megabits of data per second because of congestion in the network. 802.11n, however, allegedly can reach speeds as high as 140 megabits per second. The standard is currently in draft - Institute of Electrical and Electronics Engineers (IEEE) plans to formally ratify 802.11n by the end of 2009.
* Other 802.11 standards focus on applications of wireless networks such as wide-area network (WAN) in vehicles or technology that allows you to switch from one wireless network to another without problems.
* WiFi radios can transmit on any of three frequency bands. Or they can “frequency hop” rapidly between the different bands. Frequency hopping reduces interference and allows multiple devices to use the same wireless connection simultaneously.


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