The Global System for Mobile Communications (GSM) network architecture is a complex system that enables the delivery of mobile services to millions of users. It is based on a series of interconnected components that work together to provide reliable and efficient mobile communications.
The main components of the GSM network architecture are:
Mobile Station (MS) - this refers to the mobile device that is used by the subscriber to make calls, send text messages, and access other mobile services.
Base Station Subsystem (BSS) - this includes the Base Transceiver Station (BTS) and the Base Station Controller (BSC). The BTS is responsible for radio communication with the mobile device, while the BSC provides the connection between the BTS and the Mobile Switching Center (MSC).
Mobile Switching Center (MSC) - this is the central switching unit that handles the call processing for the mobile network. The MSC provides the connection between the BSS and the Public Switched Telephone Network (PSTN) or other mobile networks. It also manages the authentication, authorization, and accounting (AAA) functions for the network.
Home Location Register (HLR) - this is a database that contains permanent subscriber information, such as the subscriber's telephone number, the services that they are subscribed to, and the location of the Visitor Location Register (VLR) that currently serves the subscriber.
Visitor Location Register (VLR) - this is a database that contains temporary information about subscribers that are currently active within the area covered by the MSC. The VLR is used to route incoming calls to the correct mobile device and to provide information to the HLR about the current location of the subscriber.
Authentication Center (AUC) - this component is responsible for verifying the identity of the mobile device and providing encryption keys for secure communication.
Equipment Identity Register (EIR) - this is a database that contains information about the mobile devices that are authorized to access the network. The EIR is used to prevent unauthorized devices from accessing the network and to prevent the use of lost or stolen devices.
These components work together to provide seamless mobile communication services to users. When a call is made, the BTS receives the call and forwards it to the BSC, which in turn sends it to the MSC. The MSC then routes the call to the correct destination, either within the mobile network or to a different network. This process is repeated for incoming calls, with the MSC using the information in the VLR to determine the location of the mobile device and to route the call to the correct device
