what is 802.11

A family of IEEE standards for wireless LANs that were designed to extend 802.3 (wired Ethernet) into the wireless domain. The 802.11 standard is more widely known as "Wi-Fi" because the Wi-Fi Alliance, an organization independent of IEEE, provides certification for products that conform to 802.11 (see Wi-Fi Alliance).

The first 802.11 specifications were introduced in 1997 and included two spread spectrum methods for transmission in the unlicensed 2.4GHz band: 1 Mbps frequency hopping (FHSS) and 1 and 2 Mbps direct sequence (DSSS). It also included an infrared method. Both FHSS and infrared were dropped by the Wi-Fi Alliance, but the 1 Mbps DSSS method is still used by access points to advertise themselves (beaconing).

There are several specifications in the 802.11 family:

• 802.11 -- applies to wireless LANs and provides 1 or 2 Mbps transmission in the 2.4 GHz band using either frequency hopping spread spectrum (FHSS) or direct sequence spread spectrum (DSSS).
• 802.11a -- an extension to 802.11 that applies to wireless LANs and provides up to 54 Mbps in the 5GHz band. 802.11a uses an orthogonal frequency division multiplexing encoding scheme rather than FHSS or DSSS.
• 802.11b (also referred to as 802.11 High Rate or Wi-Fi) -- an extension to 802.11 that applies to wireless LANS and provides 11 Mbps transmission (with a fallback to 5.5, 2 and 1 Mbps) in the 2.4 GHz band. 802.11b uses only DSSS. 802.11b was a 1999 ratification to the original 802.11 standard, allowing wireless functionality comparable to Ethernet.
• 802.11g -- applies to wireless LANs and provides 20+ Mbps in the 2.4 GHz band.