Introduction to Wi-Fi Technology

Wi-Fi

Although the Wi-Fi technology has been around since 1985, it was widely used only after 1997. Wi-Fi or Wireless Fidelity is actually a play on words with Hi-Fi. It’s a trademark of the Wi-Fi Alliance and the brand name for products using the IEEE 802.11 family of standards.

Wi-Fi has made it cheaper and easier to create local area networks in places where cables cannot be run. As the price for chipsets for Wi-Fi continues to drop, manufacturers are building wireless network adapters not only into laptops but also into cell phones and other handheld devices.

Like all wireless technologies, Wi-Fi uses electromagnetic waves to communicate. They are transmitted on frequencies of 2.4 GHz or 5 GHz. The frequency is considerably higher than the frequencies used for cell phones, walkie-talkies and televisions. The higher frequencies allows the signal to carry more and thus make it faster than Bluetooth or Infrared.

Wi-Fi uses 802.11 networking standards, which come in many variants:

  • 802.11a : Released in September 1999, it transmits at 5GHz and can move up to 54 megabits of data per second. It also uses a more efficient coding technique called orthogonal frequency-division multiplexing (OFDM) that splits radio signal inti several sub-signals before they reach a receiver. They greatly reduces interference. It has an approximate range of 35m.
  • 802.11b : Released with 802.11a, 802.11b is the slowest and the least expensive standard. 802.11b transmits in 2.4 GHz frequency band of the radio spectrum. It can handle up to 11 megabits of data per second. Its low cost made it popular but its popularity has reduced since newer standards offer better speeds at low prices.
  • 802.11g : 802.11g was released in June 2003 and transmits at 2.4 GHz like 802.11b, but at a higher speed of 54 megabits of data per second. 802.11g is faster because it uses the same OFDM coding as 802.11a.
  • 802.11n : This is the latest standard and was released in October 2009. It transmits at 2.4 GHz using OFDM technique and offers speeds upto 150 megabits per second.

 Wi-Fi has undergone many overhauls because of security concerns. Wire Equivalent Privacy (WEP) encryption was designed to protect against casual snooping but it’s no longer considered secure. Because of WEP’s weakness the Wi-Fi Alliance approved Wi-Fi Protected Access (WPA). Though more secure WPA2 using Advanced Encryption Standard was introduced in 2004 and is supported by most new Wi-Fi devices.

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