Technical data

86 Theoretical and general applications www.westermo.com
Components in the network
ME Represents Mobile Equipment . This is equipment adapted for use on the GSM
network. Each ME unit has a unique identification (IMEI-number), International
Mobile Equipment Identity. This makes it possible for the network operator to
block the use of a unit, e.g. when a ME unit has been stolen.
SIM Stands for Subscriber Identity Module, this is a card used together with the ME-
unit. The SIM-card is furnished by the network operator and holds data such as:
telephone number, PIN code, address book, etc. The SIM-card can be moved
between different ME-units.
BTS Stands for Base Transceiver Station, which is a base radio station, i.e. a transmit-
ter and receiver that makes it possible to communicate with some form of ME.
BSC Stands for Base Station Controller; this is a substation that communicates with
the base radio station. The substation can communicate with a number of base
stations.
MSC Stands for Mobile Switching Centre which makes forwarding to an analogue,
PSTN (Public Switched Telephone Network), or an ISDN (Integrated Services
Digital Network) digital network possible.
HLR Stands for Home Location Register, which is a database that among others con-
tains basic information about the user such as the type of subscription.
VLR Stands for Visitor Location Register, which is a database that stores information
about an ME that is in a cell not controlled by HLR.
EIR Stands for Equipment. Identity Register, which registers all users on the net-
work. Identification takes place by means of the ME-unit’s IMEI-number.
AuC Stands for Authentication Centre and is a database that contains data about the
network operator and the user’s type of subscription.
PSTN
ISDN
...
BTS
BTS
BTS
MS
MS
MS
BSC
BSC
MSC
B A C K