The GSM (Global System for Mobile Communications) system architecture comprises various elements that work together to provide mobile communication services. Here are the main elements of the GSM system architecture:
1. Mobile Station (MS):
The Mobile Station represents the user equipment and consists of two main components:
a. Mobile Equipment (ME):
- The physical device carried by the user, including the handset or mobile phone.
b. Subscriber Identity Module (SIM):
- A removable smart card containing user-specific information, such as the International Mobile Subscriber Identity (IMSI) and authentication key.
2. Base Station Subsystem (BSS):
The Base Station Subsystem is responsible for the radio communication with mobile devices. It includes two key elements:
a. Base Transceiver Station (BTS):
- Houses the radio transceivers that define a cell and handle the radio communication with the mobile devices within that cell.
b. Base Station Controller (BSC):
- Manages multiple Base Transceiver Stations, handling tasks like handovers and frequency hopping.
3. Network and Switching Subsystem (NSS):
The Network and Switching Subsystem manages the communication between mobile devices and external networks. Key elements include:
a. Mobile Switching Center (MSC):
- The central component that connects calls, manages call handovers, and oversees the mobility management of mobile users.
b. Home Location Register (HLR):
- Stores subscriber information, including user profiles and subscription details.
c. Visitor Location Register (VLR):
- Maintains temporary information about subscribers within its coverage area, retrieved from the HLR.
d. Authentication Center (AUC):
- Verifies the identity of the subscriber by comparing the authentication data stored in the SIM card with that in the HLR.
e. Equipment Identity Register (EIR):
- Manages a list of valid and invalid mobile equipment to track stolen or unauthorized devices.
4. Operation and Maintenance Center (OMC):
The Operation and Maintenance Center is responsible for the management, monitoring, and maintenance of the entire GSM network.
5. Interworking Function (IWF):
The Interworking Function facilitates communication between the GSM network and other networks, such as the Public Switched Telephone Network (PSTN) or the Internet.
These elements work collaboratively to ensure the seamless provision of mobile communication services in the GSM network.