KEY TERMS

During the development of mobile systems, many terms arose which are used to describe the call cases and situations involving MSs. The primary terms used are described below. An MS can have one of the following states:

• Idle: the MS is ON but a call is not in progress
• Active: the MS is ON and a call is in progress
• Detached: the MS is OFF

The following table defines the key terms used to describe GSM mobile traffic cases (there are no traffic cases in detached mode):

 

Abbreviations:

AUC           AUthentication Center
BSC           Base Station Controller
BTS             Base Transceiver Station
EIR              Equipment Identity Register
HLR            Home Location Register
MS                Mobile Station
MSC            Mobile services Switching Center
NMC            Network Management Center
OMC          Operation and Maintenance Center
VLR            Visitor Location Register

The SS is responsible for performing call processing and subscriber related functions. It includes the following functional units:

• Mobile services Switching Center (MSC)

• Home Location Register (HLR)

• Visitor Location Register (VLR)

• AUthentication Center (AUC)

• Equipment Identity Register (EIR)

The BSS performs all the radio-related functions. The BSS is comprised of the following functional units:

• Base Station Controller (BSC)

• Base Transceiver Station (BTS)

The OMC performs all the operation and maintenance tasks for the network such as monitoring network traffic and network alarms. The OMC has access to both the SS and the BSS. MSs do not belong to any of these systems.