In-Depth
Alphabet soup
Keeping track of the established and emerging 802.11 specifications can be
confusing. What do the letters mean? They stand for the various task groups of
the Institute of Electrical and Electronic Engineers (IEEE), the standards body
that ratifies the 802.11 specification. For example, Task Group B was
responsible for 802.11b, and so on.
Here is a list of the latest additions and revisions to the spec:
802.11: This is the original WLAN standard, finalized in June 1997, and
ratified by the Institute of Electrical and Electronic Engineers (IEEE). This
standard specified a 2.4 GHz operating frequency with data rates of 1 Mbps and 2
Mbps.
802.11a: A high-speed WLAN standard for the 5 GHz band. 802.11a specifies
eight available radio channels, uses Orthogonal Frequency Division Multiplexing
(OFDM) and supports data rates up to 54 Mbps.
802.11b: The WLAN standard for 2.4 GHz band, 802.11b uses High Rate DSSS and
supports data rates of up to 11 Mbps. It specifies three available radio
channels. Most wireless LAN installations today comply with 802.11b, which is
also the basis for Wi-Fi certification from the Wireless Ethernet Compatibility
Alliance (WECA).
802.11c: This specification provides required information to
ensure proper bridge operations. Product developers utilize this standard when
developing access points.
802.11d: This specification is supplementary to the Media
Access Control (MAC) layer in 802.11. It allows access points to communicate
information on the permissible radio channels with acceptable power levels for
user devices. The 802.11 standards cannot legally operate in some countries; its
purpose is to add features and restrictions to allow WLANs to operate within the
rules of these countries.
802.11e: The 802.11e task group is currently refining the 802.11 MAC layer
to improve quality of service for better support of audio and video
applications, such as MPEG-2.
802.11f: The 802.11 standard does not currently specify the communications
between access points from different vendors. This specification, still in
development, defines inter-access-point communications to facilitate multiple
vendor-distributed WLAN networks.
802.11g: This specification will allow for higher-speed extensions in the
2.4 GHz band, up to 54 Mbps, while implementing all mandatory elements of
802.11b. It also uses OFDM instead of DSSS as the basis for providing the higher
data rate extensions.
802.11h: This specification defines the spectrum management of the 5 GHz
band for use in Europe and in APAC. It provides dynamic channel selection (DCS)
and transmits power control (TPC) for devices operating in the 5 GHz band
(802.11a). 802.11h is enabling sales of 802.11a networks in Europe.
802.11i: This is the specification that seeks to address weaknesses in the
Wired Equivalent Privacy (WEP) encryption protocol. 802.11i is actively defining
enhancements to the MAC Layer to counter problems. 802.11i will incorporate
802.1x and stronger encryption techniques, such as Advanced Encryption Standard
(AES).
See the related story ''Cutting the
cable.''