GSM is used to mean Global System for Mobile communications. GSM was designed as a circuit-switched system with the following four subsystems.
1. MOBILE STATION (MS)
Portable, vehicle-mounted, handheld device. MS contains Mobile Equipment (ME) the terminal and Subscriber Identity Module (SIM). As we require mobility of a user which is the main aim of wireless technology. It is the first part.
2. BASE STATION SUBSYSTEM (BSS)
It is the radio part; we have a controller. BSS has divided into two main parts,
3. NETWORK SWITCHING SUBSYSTEM (NSS)
It’s the core of the network. It manages the entire network. It contains databases that are;
4. NETWORK MANAGEMENT SYSTEM (NMS) / OPERATION STATION SUBSYSTEM (OSS)
Any fault of any configuration relative problems, we require OSS or NMS. It is divided into two main parts.
FUNCTIONS OF EACH ENTITY IN GSM ARCHITECTURE
1. Mobile Station (MS)
MS is connected to BTS with help of an antenna to path a signal from MS to BTS. The connection part between MS and BTS is the air interface (sometimes called Uu: User to the user interface).
2. Base Transceiver Station (BTS)
A unit that can transmit and receive is known as a transceiver. BTS has the following functions;
3. Base Station Controller (BSC)
4. Mobile Switching Center (MSC)
It is a heart of a network (the core of a network).
Home Location Register (HLR)
Visitor Location Register (VLR)
Equipment Identity Register (EIR)
Made up of three sub-classes:
EIR, checks all numbers either in the white list, black list, or gray list
Authentication Center (AUC)
Intelligent Network (IN)
All bills are checked in IN. Example pre-paid bills and all added values services are recorded in IN (Intelligent Network).
Short Message Service Center (SMSC)
It works for both store and forwards short messages. SMSC has the address of a particular SMS.
Gateway Mobile Switching Center (GMSC)
GMSC is used when we require to connect several MSC. GMSC makes it possible for international calls. For example, when you want to communicate with someone outside of your country (India and Canada). i.e. Gateway of India will contact a gateway of Canada.
Public Switched Telephone Network (PSTN)
5. Network Management Subsystem or Operation Station Subsystem (NMS / OSS)
Deals with monitoring, configuration management, and performance management. (NMS / OSS) is divided into two parts;