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call flow in 5g

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The call flow in 5G involves several steps and interactions between different network elements to establish and release connections for voice and data services. I'll provide a high-level overview of the call flow in 5G, focusing on key procedures. Note that this is a simplified explanation, and the actual call flow can vary based on specific scenarios and network configurations.

  1. Device Attachment:
    • The user device (UE - User Equipment) initiates the attachment process by sending a request to connect to the 5G network.
    • The device communicates with the gNB (Next-Generation NodeB), which is the base station in the 5G network.
  2. Registration and Authentication:
    • The UE performs a registration procedure with the network, which involves the exchange of messages to establish the UE's presence in the network.
    • Authentication and key generation procedures are performed to ensure the security of the communication.
  3. Establishing a PDU Session:
    • The Packet Data Unit (PDU) session is established to enable data communication between the UE and the 5G core network.
    • The gNB sends a request to the Access and Mobility Management Function (AMF) in the core network to set up the PDU session.
  4. Session Management:
    • The AMF communicates with the User Plane Function (UPF) to establish the data path for the PDU session.
    • The UPF is responsible for managing user data forwarding.
  5. Bearer Setup:
    • The AMF initiates a request to the Session Management Function (SMF) for the setup of the bearer.
    • The SMF communicates with the gNB to establish the bearers needed for communication.
  6. Handover (Optional):
    • In the case of mobility, where the UE moves between cells, a handover procedure may occur.
    • The source gNB and target gNB coordinate the handover process to ensure a seamless transition.
  7. Data Transfer:
    • Once the connection is established, data can be transferred between the UE and the network.
  8. Call Release:
    • When the communication session is complete or the UE moves out of coverage, a call release procedure is initiated.
    • The network elements release resources and update their states accordingly.