Asus WL-160G User Manual download pdf (Page 58)

5. Appendix

58 ASUS 802.11g Access Point

Chapter 5 - Appendix

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.

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.

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Asus WL-160G User Manual Page 58