D-2
InterReach Unison Installation, Operation, and Reference Manual
CONFIDENTIAL
D-620003-0-20 Rev J
BSC
Base Station Controller. A GSM term referring to the device in charge of man-
aging the radio interface in a GSM system, including the allocation and release of
radio channels and hand-off of active calls within the system.
BTA
Basic Trading Area. The U.S. and its territories are divided into 493 areas,
called BTAs. These BTAs are composed of a specific list of counties, based on a
system originally developed by Rand McNally. The FCC grants licenses to wire-
less operators to provide service within these BTAs and/or MTAs. (See MTA.)
BTS
Base Transceiver Station. A GSM term referring to the group of network
devices that provide radio transmission and reception, including antennas.
C/I
Carrier to interference ratio. The ratio of the desired signal strength to the com-
bined interference of all mobile phones using the system. Usually, the interfer-
ence of most concern is that provided by mobile phones using the same channel
in the system. These are referred to as “co-channel interferers.”
CCITT
Consultative Committee on International Telephone and Telegraph. This
organization sets international communications standards. The CCITT is now
known as ITU (the parent organization).
CDMA
Code Division Multiple Access. A digital wireless access technology that
uses spread-spectrum techniques. Unlike alternative systems, such as GSM, that
use time-division multiplexing (TDM), CDMA does not assign a specific fre-
quency to each user. Instead, every channel uses the full available spectrum.
Individual conversations are assigned a unique code which allows the conversa-
tion to be spread out over multiple channels; transmitted to the far end; and
re-assembled for the recipient using a specific code.
CDPD
Cellular Digital Packet Data. CDPD allows data transmission over the ana-
log wireless network. CDPD breaks data into packets and transmits these packets
on idle portions of the network.
Cell
A cell defines a specific, physical area of coverage of a portion of a wireless
system. It is the basic “building block” of all modern wireless communications
systems.
Cell Site
A term which refers to the location of the transmission equipment (e.g.,
basestation) within the cell.
CEPT
Conference of European Postal and Telecommunications Administrations.
This organization’s mandate is to define pan-European wireless communications
standards. In 1982, CEPT mandated GSM as the access protocol for public wire-
less communications systems across Europe.
Channel
The path along which a communications signal is transmitted. Channels
may be simplex (communication occurs in only one direction), duplex (commu-
nication occurs in both directions) or full duplex (communication occurs in both
directions simultaneously).
