D-4
InterReach Unison Installation, Operation, and Reference Manual
CONFIDENTIAL
D-620003-0-20 Rev J
Fixed
An ITU definition for radio communications between specified fixed points.
Point-to-point high-frequency circuits and microwave links are two examples of
fixed applications.
FM
Frequency Modulation. A method of transmitting information in which the fre-
quency of the carrier is modified according to a plan agreed to by the transmitter
and the receiver. FM can be either analog or digital.
Forward Channel
Refers to the radio channel that sends information from the base
station to the mobile station. (See Reverse Channel.)
Frequency
The number of times an electrical signal repeats an identical cycle in a
unit of time, normally one second. One Hertz (Hz) is one cycle per second.
Frequency re-use
The ability to use the same frequencies repeatedly across a cellu-
lar system. Because each cell is designed to use radio frequencies only within its
boundaries, the same frequencies can be reused in other cells not far away with
little potential for interference. The reuse of frequencies is what enables a cellu-
lar system to handle a huge number of calls with a limited number of channels.
Gain
The increase in power that occurs when any signal is amplified, usually
through an amplifier or antenna.
GHz
Gigahertz. A measure of frequency equal to one billion hertz.
GSM
Groupe Speciale Mobile (now translated in English as Global Standard for
Mobile Communications). GSM is the digital wireless standard used throughout
Europe, in much of Asia, as well as by some operators in the U.S. and South
America.
Handoff
The process by which the wireless system passes a wireless phone conver-
sation from one radio frequency in one cell to another radio frequency in another
as the caller moves between two cells. In most systems today, this handoff is per-
formed so quickly that callers don’t notice.
Hertz
A measurement of electromagnetic energy, equivalent to one “wave” per sec-
ond. Hertz is abbreviated as “Hz”.
iDEN
Integrated Digital Enhanced Network. A TDMA-based wireless access tech-
nology that combines two-way radio, telephone, text message, and data transmis-
sion into one network. This system was developed by Motorola. In the U.S.,
iDEN is used by Nextel in its network.
IEEE
The Institute of Electrical and Electronics Engineers. The world’s largest
technical professional society with members from more than 130 countries. The
IEEE works to advance the theory and practice of electrical, electronics, com-
puter engineering and computer science.
Infrastructure
A term used to encompass all of the equipment, including both hard-
ware and software, used in a communications network.
