Asus WL-320gP - Wireless Access Point User Manual page 56

Chapter  - Appendix
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.
Compared with 802.11g: 802.11a is a standard for access points and radio
NICs that is ahead of 802.11g in the market by about six months. 802.11a
operates in the 5GHz frequency band with twelve separate non-overlapping
channels. As a result, you can have up to twelve access points set to different
channels in the same area without them interfering with each other. This
makes access point channel assignment much easier and significantly
increases the throughput the wireless LAN can deliver within a given area.
In addition, RF interference is much less likely because of the less-crowded
5 GHz band.
IEEE 802.11b (11Mbits/sec)
In 1997, the Institute of Electrical and Electronics Engineers (IEEE) adopted
the 802.11 standard for wireless devices operating in the 2.4 GHz frequency
band. This standard includes provisions for three radio technologies: direct
sequence spread spectrum, frequency hopping spread spectrum, and infrared.
Devices that comply with the 802.11 standard operate at a data rate of either
1 or 2 Mbps.
In 1999, the IEEE created the 802.11b standard. 802.11b is essentially
identical to the 802.11 standard except 802.11b provides for data rates of
up to 11 Mbps for direct sequence spread spectrum devices. Under 802.11b,
direct sequence devices can operate at 11 Mbps, 5.5 Mbps, 2 Mbps, or 1
Mbps. This provides interoperability with existing 802.11 direct sequence
devices that operate only at 2 Mbps.
Direct sequence spread spectrum devices spread a radio signal over a range of
frequencies. The IEEE 802.11b specification allocates the 2.4 GHz frequency
band into 14 overlapping operating Channels. Each Channel corresponds to
a different set of frequencies.
IEEE 802.11g
802.11g is a proposed (to be finalized) new extension to 802.11b (used in
6 ASUS 802.11g Access Point