Tuesday, June 12, 2007

A brief introdution to IEEE 802.11

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). The term 802.11x is also used to denote the set of amendments to the standard. The term IEEE 802.11 is also used to refer to the original 802.11 (1997), which is now sometimes called "802.11 legacy". For the application of these standards see Wi-Fi.

A Linksys Residential gateway with a 802.11b radio and a 4-port ethernet switch. A Compaq 802.11b PCI cardThe 802.11 family currently includes multiple over-the-air modulation techniques that all use the same basic protocol. The most popular techniques are those defined by the b/g and are amendments to the original standard; security was originally purposefully weak due to multi-governmental meddling on export requirements and was later enhanced via the 802.11i amendment after governmental and legislative changes. 802.11n is a new multi-streaming modulation technique that has recently been developed; the standard is still under draft development, although products based on proprietary pre-draft versions of the standard are being sold. Other standards in the family (c–f, h, j) are service amendments and extensions or corrections to previous specifications. 802.11b was the first widely accepted wireless networking standard, followed by 802.11g and then 802.11n.

802.11b and 802.11g standards use the 2.4 GHz (gigahertz) band, operating (in the United States) under Part 15 of the FCC Rules and Regulations. Because of this choice of frequency band, 802.11b and 802.11g equipment will suffer interference from microwave ovens, cordless telephones, Bluetooth devices, baby and security monitors, amateur radio and other appliances using this same band. The 802.11a standard uses a different 5 GHz band, which is clean by comparison. 802.11a devices are not affected by products operating on the 2.4 GHz band.
The segment of the radio frequency spectrum used varies between countries. While it is true that in the U.S. 802.11a and g devices may be legally operated without a licence. Unlicensed (legal) operation of 802.11 a & g is covered under Part 15 of the FCC Rules and Regulations. Frequencies used by channels one (1) through six (6) (802.11b) fall within the range of the 2.4 gigahertz amateur radio band. Licensed amateur radio operators may operate 802.11b/g devices under Part 97 of the FCC Rules and Regulations, allowing increased power output but not allowing any commercial content or encryption.

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