ASUS WLAN Card
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Chapter 5
Chapter 5 - Glossary
Glossary
IEEE
The Institute of Electrical and Electronics Engineers. The IEEE sets standards
for networking, including Ethernet LANs. IEEE standards ensure
interoperability between systems of the same type.
IEEE 802.11
IEEE 802.xx is a set of specifications for LANs from the Institute of Electrical
and Electronic Engineers (IEEE). Most wired networks conform to 802.3, the
specification for CSMA/CD based Ethernet networks or 802.5, the specification
for token ring networks. 802.11 defines the standard for wireless LANs
encompassing three incompatible (non-interoperable) technologies: Frequency
Hopping Spread Spectrum (FHSS), Direct Sequence Spread Spectrum (DSSS),
and Infrared. 802.11 specifies a carrier sense media access control and physical
layer specifications for 1 and 2 Mbps wireless LANs.
IEEE 802.11a (54Mbits/sec)
Compared with 802.11b: The 802.11b standard was designed to operate in
the 2.4-GHz ISM (Industrial, Scientific and Medical) band using direct-sequence
spread-spectrum technology. The 802.11a standard, on the other hand, was
designed to operate in the more recently allocated 5-GHz UNII (Unlicensed
National Information Infrastructure) band. And unlike 802.11b, the 802.11a
standard departs from the traditional spread-spectrum technology, instead using
a frequency division multiplexing scheme that's intended to be friendlier to
office environments.
The 802.11a standard, which supports data rates of up to 54 Mbps, is the Fast
Ethernet analog to 802.11b, which supports data rates of up to 11 Mbps. Like
Ethernet and Fast Ethernet, 802.11b and 802.11a use an identical MAC (Media
Access Control). However, while Fast Ethernet uses the same physical-layer
encoding scheme as Ethernet (only faster), 802.11a uses an entirely different
encoding scheme, called OFDM (orthogonal frequency division multiplexing).
The 802.11b spectrum is plagued by saturation from wireless phones, microwave
ovens and other emerging wireless technologies, such as Bluetooth. In contrast,
802.11a spectrum is relatively free of interference.
The 802.11a standard gains some of its performance from the higher frequencies
at which it operates. The laws of information theory tie frequency, radiated
power and distance together in an inverse relationship. Thus, moving up to the
5-GHz spectrum from 2.4 GHz will lead to shorter distances, given the same
radiated power and encoding scheme.
