Wi-Fi
Last modified: Friday, January 16, 2004
Short for wireless fidelity and is meant to be used generically when referring of any type of 802.11
network, whether 802.11b, 802.11a, dual-band, etc. The term is promulgated by the Wi-Fi Alliance.
Any products tested and approved as "Wi-Fi Certified" (a registered trademark) by the Wi-Fi Alliance
are certified as interoperable with each other, even if they are from different manufacturers. A user
with a "Wi-Fi Certified" product can use any brand of access point with any other brand of client
hardware that also is certified. Typically, however, any Wi-Fi product using the same radio frequency
(for example, 2.4GHz for 802.11b or 11g, 5GHz for 802.11a) will work with any other, even if not
"Wi-Fi Certified."
Formerly, the term "Wi-Fi" was used only in place of the 2.4GHz 802.11b standard, in the same way
that "Ethernet" is used in place of IEEE 802.3. The Alliance expanded the generic use of the term in an
attempt to stop confusion about wireless LAN interoperability.
Also see the Wireless LAN Standards chart in the Quick Reference section of Webopedia.
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802.11
Last modified: Tuesday, February 03, 2004
802.11 refers to a family of specifications developed by the IEEE for wireless LAN technology. 802.11
specifies an over-the-air interface between a wireless client and a base station or between two wireless
clients. The IEEE accepted the specification in 1997.
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.
Also see the Wireless LAN Standards chart in the Quick Reference section of Webopedia.
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Wi-Fi Alliance
Last modified: Thursday, October 17, 2002
An organization made up of leading wireless equipment and software providers with the missions of
certifying all 802.11-based products for interoperability and promoting the term Wi-Fi as the global
brand name across all markets for any 802.11-based wireless LAN products.
While all 802.11a/b/g products are called Wi-Fi, only products that have passed the Wi-Fi Alliance
testing are allowed to refer to their products as "Wi-Fi Certified" (a registered trademark). Products that
pass are required to carry an identifying seal on their packaging that states "Wi-Fi Certified" and
indicates the radio frequency band used (2.5GHz for 802.11b or 11g, 5GHz for 802.11a)
This group was formerly known as the Wireless Ethernet Compatibility Alliance (WECA) but changed
its name in October 2002 to better reflect the Wi-Fi brand it wants to build.
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RF
Last modified: Monday, May 12, 2003
Short for radio frequency, any frequency within the electromagnetic spectrum associated with radio
wave propagation. When an RF current is supplied to an antenna, an electromagnetic field is created
that then is able to propagate through space. Many wireless technologies are based on RF field
propagation.
These frequencies make up part of the electromagnetic radiation spectrum:
* Ultra-low frequency (ULF) -- 0-3 Hz
* Extremely low frequency (ELF) -- 3 Hz - 3 kHz
* Very low frequency (VLF) -- 3kHz - 30 kHz
* Low frequency (LF) -- 30 kHz - 300 kHz
* Medium frequency (MF) -- 300 kHz - 3 MHz
* High frequency (HF) -- 3MHz - 30 MHz
* Very high frequency (VHF) -- 30 MHz - 300 MHz
* Ultra-high frequency (UHF)-- 300MHz - 3 GHz
* Super high frequency (SHF) -- 3GHz - 30 GHz
* Extremely high frequency (EHF) -- 30GHz - 300 GHz
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WLAN
Last modified: Friday, January 16, 2004
Acronym for wireless local-area network. Also referred to as LAWN. A type of local-area network that
uses high-frequency radio waves rather than wires to communicate between nodes.
Also see the Wireless LAN Standards chart in the Quick Reference section of Webopedia.