GSM NETWORK COMPONENTS

   The GSM network is divided into two systems. Each of these systems are comprised of a number of functional units which are individual components of the mobile network. The two systems are:
              • Switching System (SS)
              • Base Station System (BSS)
    In addition, as with all telecommunications networks, GSM networks are operated, maintained and managed from computerized centers.

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.

Note :
MSs do not belong to any of these systems.