GSM Network Architecture

The Global System for Mobile Communications (GSM) is a widely used cellular network standard for mobile communication. It is based on a hierarchical network architecture consisting of several functional entities that work together to provide seamless communication services to users. One of these entities is the Network Switching Subsystem (NSS).

Role of Network Switching Subsystem (NSS)

The Network Switching Subsystem (NSS) is responsible for managing the switching function in a GSM network. It is a core component of the GSM architecture and plays a crucial role in establishing and maintaining calls between mobile devices.

Functions of Network Switching Subsystem (NSS)

The NSS consists of several elements that work together to provide various functions:

1. Mobile Switching Center (MSC): The MSC is the main component of the NSS and is responsible for handling the switching of calls. It acts as a central hub for connecting mobile devices to other MSCs or to external networks such as the Public Switched Telephone Network (PSTN) or the Internet. The MSC also performs call routing, call setup, and call termination functions.

2. Visitor Location Register (VLR): The VLR is a database that stores temporary information about mobile devices that are currently located within the coverage area of a particular MSC. It contains data such as the mobile device's identity, location, and service subscription information. The VLR helps in quickly locating and routing calls to the appropriate MSC for mobile devices that are currently within its coverage area.

3. Home Location Register (HLR): The HLR is a central database that stores permanent information about each subscriber in the GSM network. It contains data such as the subscriber's identity, service profile, location, and authentication information. The HLR acts as a reference point for various network entities to retrieve subscriber information when needed.

4. Authentication Center (AuC): The AuC is responsible for providing authentication and encryption services to ensure secure communication between the mobile device and the network. It generates authentication parameters and keys that are used to authenticate the mobile device during the registration process and to encrypt the communication between the mobile device and the network.

5. Equipment Identity Register (EIR): The EIR is a database that stores information about the mobile devices that are allowed or blocked from accessing the network. It helps in identifying stolen or unauthorized devices and prevents them from being used in the network.

Conclusion

In summary, the Network Switching Subsystem (NSS) in GSM manages the switching function in the network. It consists of various elements such as the MSC, VLR, HLR, AuC, and EIR, which work together to establish and maintain calls, authenticate mobile devices, and manage subscriber information. The NSS plays a critical role in providing seamless communication services to GSM users.