802.11 Wireless Network Site Surveying and Installation

396 adjacent cell

A

adjacent cell. A coverage area of an AP that is physically located next to an

existing AP’s coverage area.

adjacent channel. A channel or frequency that is directly above or below a

specific channel or frequency.

AES. Advanced Encryption Standard. A next-generation encryption function

approved by the National Institute of Standards and Technology (NIST) for use

with WLAN. The encryption mechanism to be used in 802.11i and is likely to

replace DES and 3DES.

aggregate throughput. A measure of the maximum amount of data a network or

other communications system can carry in a given timeframe. Basically a total

summation of all data rates of all simultaneous transmissions possible at one

instance on the system. If a system could support five simultaneous transmissions

of 2 Mbps, for example, it would have an aggregate throughput of 10 Mbps.

amplitude. The magnitude or strength of a varying waveform.

amplitude modulation (AM). A technique whereby the voltage level or

amplitude of a carrier is varied to transmit digital or analog information.

antenna. The part of a radio communications system intended to radiate and/or

collect RF energy.

antenna gain. A relative measure of an antenna’s capability to direct or

concentrate RF energy in a particular direction or pattern. Typically measured in

dBi or dBd. See also dBi and dBd.

AP. access point. The central point of communications for all stations in a

WLAN. An AP provides connection between wireless devices as well as between

the wired network and the wireless network.

attenuation. A reduction in strength or deterioration of a radio signal as it passes

through a transmission medium. Attenuation generally increases with frequency,

cable length, and the number of connections in a circuit. Attenuation is measured

in decibels (dB).

attenuator. A device that reduces the level of a transmitted signal, in terms of

current, voltage, or power.