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5g pdu session establishment procedure

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The 5G Protocol Data Unit (PDU) session establishment procedure involves the setup of a communication session between a user equipment (UE) and the 5G core network. The PDU session is a logical connection through which data is transferred between the UE and the network. Here is a technical explanation of the 5G PDU session establishment procedure:

  1. UE Registration: Before establishing a PDU session, the UE needs to register with the 5G core network. This involves procedures like initial registration and authentication to ensure the identity and capabilities of the UE.
  2. Service Request: The UE initiates a service request to the 5G core network, indicating its intention to establish a PDU session. This request is typically triggered by the user or by an application requiring network connectivity.
  3. Session Management: The Session Management function in the 5G core network is responsible for handling PDU session-related procedures. It initiates the PDU session establishment procedure upon receiving the service request from the UE.
  4. Policy and Charging Control (PCC): The PCC function plays a crucial role in determining policy rules and charging aspects associated with the PDU session. It may involve checking subscription profiles and enforcing policies related to Quality of Service (QoS), traffic handling, etc.
  5. Authentication and Authorization: The UE undergoes authentication and authorization procedures to ensure that it is allowed to establish a PDU session. This involves validating the UE's identity and checking its subscription status.
  6. Access and Mobility Management: The Access and Mobility Management function handles the allocation of resources and mobility-related aspects, ensuring that the UE can access the desired service and maintain connectivity as it moves within the network.
  7. Bearer Setup: The establishment of a PDU session involves setting up one or more bearers. A bearer is a logical channel that carries user data with specific QoS characteristics. The network allocates resources and establishes bearers based on the negotiated QoS parameters.
  8. Data Forwarding: Once the bearers are set up, data can be forwarded between the UE and the network. This data forwarding may involve the establishment of a data path through the user plane, ensuring that user data is efficiently transmitted between the UE and the desired network destination.
  9. Session Establishment Confirmation: The 5G core network sends a confirmation to the UE, indicating that the PDU session has been successfully established. This confirmation may include details about the established bearers, QoS parameters, and other relevant information.

Throughout these steps, signaling messages are exchanged between the UE and the network nodes involved in the PDU session establishment. The signaling is based on protocols such as the Session Management Protocol (SMP) and other 3GPP-defined protocols. The details may vary based on the specific scenario and deployment configurations.