Wi-Fi
From Isopedia
Wi-Fi
Technical Information:
Wifi is the new wireless way to handle networking. It is known as wireless networking and 802.11 networking. WiFi is short for wireless fidelity and is meant to be used generically when referring of any type of 802.11network. It is a simple way to connect computers in the home or office without having to use any wires and instead using an access point. Each cell is controlled by Access Point (AP) - a sort of base station. Although wireless LAN can consist of one cell, in big networks we can distinguish groups of cells called Extended Service Sets. All Access Points are connected by a skeleton network. Computers can be up to 100 feet apart and use radio signals to connect to the network. 802.11 family is composed of several standards operating in different radio frequencies. The most commonly used radio signal is 802.11b which operates in the 2.40 GHz - 2.4835 GHz band and the typical range is 75-100 meters. Another radio frequency used is 802.11a. The frequency range is 5.725 GHz to 5.850 GHz, and the 5 GHz frequency band is not as crowded as the 2.4 GHz, because it offers more radio channels. The typical range of this frequency is only 50 meters. The recently most approved frequency is 802.11g. The 5 GHz frequency band is not as crowded as the 2.4 GHz, because it offers more radio channels and is compatible with 802.11b because of the 2,4 GHz range, but uses a different radio technology in order to boost overall bandwidth.
Wifi uses a technique known as orthogonal frequency-division multiplexing. The radio signals used for WiFi can change frequencies and transmit onto any three bands, or they can split the available radio bandwidth into different channels and hop between them. By using frequency hopping, it allows WiFi cards to work simultaneously without interfering with each other. A hotspot is a connection point for a WiFi network. It is a small box that is hardwired into the Internet. The box contains an 802.11 radio that can simultaneously talk to up to 100 or so 802.11 cards. Hotspots can be created within the home, and more public places are installing hotspots. Hotspots can be open or secure, when they are open anyone with a card can access the hotspot. When the hotspot is secure, the user need to know a WEP key to access the internet. The WEP key is an encryption system for the data sent through 802.11. To create a hotspot in the home, the customer would need a box that contains a port to connect to a cable modem or DSL, a router, an Ethernet hub, a firewall, and a wireless access point. Next you connect through wireless cards and gain up to 100 feet of wireless access throughout the house.
Historical Information:
In 1991, in the Netherlands, WiFi was invented by NCR Corporation/AT&T, later on becoming Lucent & Agere Systems. The initial purpose of the invention was for cashier systems, and was brought onto the market under the name WaveLAN. The father and inventor of WiFi, Vic Hayes, worked with his team and designed the standards. The WiFi alliance describes WLAN products that are based on 802.11 standards. The main purpose of its members is examining the compatibility, certifying and promoting hardware designed for Wi-Fi net.
The first wireless LANs came into being in 1994. Then Wi-Fi cards were so expensive and this decreased its development. In 1997 the Institute of Electrical and Electronic Engineers worked out the 802.11 standard. There was a very low capacity, and in 1999 they introduced the 802.11b standard which brought higher capacities. The next step in the evolution of Wi-Fi was the 802.11a standard creation. The 802.11a was theoretically faster, however it was more expensive which decreased support. In 2002, at trade fair "Comdex 2002", there were presented some devices which could work in the new 802.11g standard. In 2003 this standard gained approval of IEEE and appeared in most producers' offers. 802.11g joins the capacity which is comparable to "a" and has the range like the "b" one.
References:
http://computer.howstuffworks.com/wireless-network.htm
http://www.webopedia.com/TERM/W/Wi_Fi.html
Team Members:
- Sheila Hughes
- Jake Pelletier
- Dan Luby
- Gabrielle Davila
- Mamadou Diakhate
