A GSM network consists of the following components:
Mobile station. The
GSM mobile station (or mobile phone) communicates with other parts
of the system through the base-station system.
GSM Base station system
Base transceiver station (BTS). The base transceiver station (BTS) handles
the radio interface to the mobile station. The base transceiver
station is the radio equipment (transceivers and antennas)
Base station controller
(BSC). The BSC provides the control functions and physical links
between the MSC and BTS. It provides functions such as
handover, cell configuration data and control of RF power levels
in base transceiver stations. A number of BSCs are served
by a MSC.
GSM Switching System
Mobile services switching center (MSC).
The MSC performs the telephony switching functions of the system.
It also performs such functions as toll ticketing, network interfacing,
common channel signalling, and others.
Home location register (HLR). The
HLR database is used for storage and management of subscriptions.
The home location register stores permanent data about subscribers, including
a subscriber's service profile, location information, and activity status.
location register (VLR). The VLR database contains temporary information about
subscribers that is needed by the mobile services switching center
(MSC) in order to service visiting subscribers. When a mobile
station roams into a new mobile services switching center (MSC)
area, the visitor location register (VLR) connected to that MSC
will request data about the mobile station from the HLR,
reducing the need for interrogation of the home location register
Authentication center (AUC). The AUC provides authentication and encryption
parameters that verify the user's identity and ensure the confidentiality
of each call. The authentication center (AUC) also protects network
operators from fraud.
Equipment identity register (EIR). The EIR database
contains information on the identity of mobile equipment to prevent
calls from stolen, unauthorized or defective mobile stations.
Message center (MXE).
The MXE is a node that provides integrated voice, fax,
and data messaging.
Mobile service node (MSN). The MSN is
the node that handles the mobile intelligent network (IN) services.
Gateway mobile services switching center (GMSC). A gateway mobile services
switching center (GMSC) is a node used to interconnect two
GSM interworking unit (GIWU). The GIWU consists of both
hardware and software that provides an interface to various networks
for data communications. Through the GSM interworking unit (GIWU), users
can alternate between speech and data during the same call.
and support system (OSS). The OSS is the functional entity
from which the network operator monitors and controls the system.
The purpose of operation and support system is to offer
support for centralized, regional, and local operational and maintenance activities
that are required for a GSM network.
Other topics in our resources on GSM related to GSM Architecture include: