The GSM network architecture is divided into three primary subsystems that manage communication, switching, and operations:
Uses the Subscriber Identity Module (SIM) to store unique identity information. Security is maintained through a challenge-response authentication mechanism and over-the-air encryption using algorithms like A5. GSM – Architecture, Protocols and Services
Uses modified versions of LAPD (called LAP-Dm) for the air interface and SS7 protocols (MTP) for the network interface. Layer 3 (Network): Divided into three sublayers: The GSM network architecture is divided into three
Manages radio links and dedicated channel allocation. and the Base Station Controller (BSC)
Handles the radio link with mobile devices. It includes the Base Transceiver Station (BTS) , which contains the radio transmitters and receivers, and the Base Station Controller (BSC) , which manages radio resources and handovers for multiple BTSs.