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Academic Computing Services (ACS)

Academic Computing Services (ACS). ACS, the nationwide organization that assists colleges and universities with technology issues. http://www.greghughes.net/images/wifi.jpg. What is WI FI ?. A wireless network uses radio waves, just like cell phones, televisions and radios do.

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Academic Computing Services (ACS)

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  1. Academic Computing Services (ACS) ACS, the nationwide organization that assists colleges and universities with technology issues. http://www.greghughes.net/images/wifi.jpg

  2. What is WI FI ? • A wireless network uses radio waves, just like cell phones, televisions and radios do. • 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. It sends the information to the Internet using a physical, wired Ethernet connection. ..and this is WI FI!

  3. How WIFI Works http://images.google.com/imgres?imgurl=http://static.howstuffworks.com/gif/wifi-phone-3.jpg&imgrefurl=http://electronics.howstuffworks.com/wifi-ph one2.htm&h=340&w=450&sz=43&hl=en&start=1&tbnid=frXqduk7W2QnnM:&tbnh=96&tbnw=127&prev=/images%3Fq%3Dwifi%26gbv%3D2%26hl%3Den%26sa%3DG

  4. WIFI Communication • 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 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.

  5. http://www.dailycupoftech.com/wp-content/uploads/2007/06/good-wifi.pnghttp://www.dailycupoftech.com/wp-content/uploads/2007/06/good-wifi.png

  6. IEEE 802.11 IEEE 802.11 networking standards come in several flavors: o 802.11a transmits at 5GHz 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. o 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 complimentary code keying (CCK) coding.

  7. IEEE 802.11, cont. o 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. o 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.

  8. IEEE 802.11 Architecture • The basic service set (BSS) is the basic building block of an IEEE 802.11 LAN and this consists of devices referred to as stations (STA). Basically, the set of STAs which can talk to each other can form a BSS. • Multiple BSSs are interconnected through an architectural component, called distribution system (DS), to form an extended service set (ESS). An access point (AP) is a STA that provides access to DS by providing DS services. If the LAN just consists of single BSS, then that is called independent BSS (IBSS).

  9. IEEE 802.11 Architecture cont. http://images.google.com/imgres?imgurl=http://www.cs.utexas.edu/~ypraveen/surveys/wlan_security/img1.gif&imgrefurl=http://www.cs.utexas.edu/~yprave en/surveys/wlan_security/node2.html&h=425&w=573&sz=8&hl=en&start=5&tbnid=Z5elaoxvVOsbeM:&tbnh=99&tbnw=134&prev=/images%3Fq%3DIEEE%2B8 02.11%26gbv%3D2%26hl%3Den%26sa%3DG

  10. Other Wireless Networking Standards • Another wireless standard with a slightly different number, 802.15, is used for Wireless Personal Area Networks (WPANs). It covers a very short range and is used for Bluetooth technology. • WiMax, also known as 802.16, looks to combine the benefits of broadband and wireless. WiMax will provide high-speed wireless Internet over very long distances and will most likely provide access to large areas such as cities. WiMax technology will be available in most American cities in 2008.

  11. http://images.google.com/imgres?imgurl=http://kunz-pc.sce.carleton.ca/MESH/architecture.jpg&imgrefurl=http://kunz-pc.sce.car leton.ca/MESH/index.htm&h=777&w=978&sz=87&hl=en&start=3&tbnid=sugY4Q4P_KtZrM:&tbnh=118&tbnw=149&prev=/images %3Fq%3DIEEE%2B802.11%26gbv%3D2%26hl%3Den%26sa%3DG

  12. Note on devices 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.

  13. http://images.google.com/imgres?imgurl=http://blog.motiwala.com/wp-content/uploads/2007/06/wifi-web.jpg&imgrefurl=http://blog.motiwala.com/category /ideas&h=375&w=500&sz=34&hl=en&start=13&tbnid=xGxc35aeXTdSGM:&tbnh=98&tbnw=130&prev=/images%3Fq%3Dwifi%26gbv%3D2%26hl%3Den%26sa%3DG

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