User's Manual

Microcell: A bounded physical space in which a number of wireless devices can communicate.
Because it is possible to have overlapping cells as well as isolated cells, the boundaries of the
cell are established by some rule or convention.
Microwave: Technically, the term describes any frequency above 1.0 GHz. Unfortunately the
advertising industry has contorted this meaning considerably. In our discussion we will stick to
the technical definition.
Multipath: The signal variation caused when radio signals take multiple paths from transmitter
to receiver.
O
Orthogonal Frequency Division Multiplexing (OFDM): A modulation technique for
transmitting large amounts of digital data over radio waves. 802.11a uses OFDM, as will
802.11g.
P
Peer-to-Peer Mode: A wireless network structure that allows wireless clients to communicate
with each other without using an access point.
Personal Area Network (PAN): A personal area network, or PAN, is a networking scheme that
enables computing devices such as PCs, laptop computers, handheld personal computers,
printers and personal digital assistants (PDAs) to communicate with each other over short
distances either with or without wires.
Preamble: A preliminary signal transmitted over a WLAN to control signal detection and clock
synchronization.
R
Radio Frequency (RF) Terms (GHz, MHz, Hz): The international unit for measuring frequency
is Hertz (Hz), which is equivalent to the older unit of cycles per second. One Mega-Hertz (MHz)
is one million Hertz. One Giga-Hertz (GHz) is one billion Hertz. For reference: the standard US
electrical power frequency is 60 Hz, the AM broadcast radio frequency band is 0.55 -1.6 MHz,
the FM broadcast radio frequency band is 88-108 MHz, and microwave ovens typically operate
at 2.45 GHz.
Range: The distance over which a given system can communicate. This subject is discussed in
detail below.
RC4: An encryption algorithm designed at RSA Laboratories; specifically, a stream cipher of
pseudo-random bytes that is used in WEP encryption.
Remote Authentication Dial-In User Service (RAID): An authentication and accounting
system that verifies users' credentials and grants access to requested resources.
Roaming: Movement of a wireless node between two microcells. Roaming usually occurs in
infrastructure networks built around multiple access points.
S
Service Set Identifier (SSID): Used to identify clients on a wireless network.
Shared key An encryption key known only to the receiver and sender of data.
Site Survey: A process where you set up one transceiver in a fixed location, and then use
another unit to plot the field strength of the first unit’s transmitted signal. By moving the
transmitter around, and repeating the plots, you can develop a plan as to the best locations for
access points. You will also identify dead zones and other areas in need of special attention.
This can be a long, slow process, but it beats ripping up an unsatisfactory installation and
starting over. These tests require special software commands. Refer to your manual for specific
instructions. If you have a very large, or unusually complex installation situation, you might want
to consider calling in professionals to do your survey. We are not permitted to suggest installer
names, but you can check your yellow pages or similar sources for likely candidates.
T
Transceiver: A commonly used term that describes a combination transmitter and receiver.
Both 802.11a and 802.11b devices would be properly described as data transceivers.
U