Asus USB-N66 - Manual (Page 25)

USB-N66 WLAN Adapter User Manual
2 ASUS WLAN adapter
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 5GHz 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 11Mbps
for direct sequence spread spectrum devices. Under 802.11b, direct sequence
devices can operate at 11Mbps, 5.5Mbps, 2Mbps, or 1Mbps. This provides
interoperability with existing 802.11 direct sequence devices that operate only
at 2Mbps.
Direct sequence spread spectrum devices spread a radio signal over a range
of frequencies. The IEEE 802.11b specification allocates the 2.4GHz frequency
band into 14 overlapping operating Channels. Each Channel corresponds to a
different set of frequencies.
IEEE 802.11g
802.11g is a new extension to 802.11b (used in majority of wireless LANs today)
that broadens 802.11b’s data rates to 54 Mbps within the 2.4 GHz band using
OFDM (orthogonal frequency division multiplexing) technology. 802.11g allows
backward compatibility with 802.11b devices but only at 11 Mbps or lower,
depending on the range and presence of obstructions.
Infrastructure
A wireless network centered about an access point. In this environment, the
access point not only provides communication with the wired network but also
mediates wireless network traffic in the immediate neighborhood.