Sign in Subscribe

5g pcf call flow

Last updated on 

The 5G Packet Control Function (PCF) plays a crucial role in the 5G core network, specifically in the control and management of policy and charging. PCF manages the policies for user data and ensures that they align with the operator's business rules and subscriber agreements. Here's a simplified overview of a 5G PCF call flow:

  1. UE (User Equipment) Attach:
    • The User Equipment initiates the attach procedure by sending an Attach Request to the Access and Mobility Management Function (AMF).
    • The AMF authenticates the UE and establishes a security context.
  2. Registration with the PCF:
    • After successful authentication, the AMF registers the UE with the PCF.
    • The PCF allocates resources and establishes policies for the UE.
  3. Policy and Charging Control (PCC) Establishment:
    • The PCF communicates with the Policy and Charging Rules Function (PCRF) to establish PCC rules for the UE.
    • PCRF determines the policies for the user based on operator-defined rules and subscriber profiles.
  4. PDU Session Establishment:
    • The PCF communicates with the Session Management Function (SMF) to establish a PDU (Packet Data Unit) session for the UE.
    • SMF is responsible for managing the data plane connectivity.
  5. Policy Enforcement during Data Session:
    • As the UE engages in data sessions, the PCF enforces the established policies. This includes managing Quality of Service (QoS), applying traffic steering policies, and ensuring compliance with operator-defined rules.
  6. Dynamic PCC Rule Update:
    • The PCF monitors the session and may dynamically update PCC rules based on real-time conditions, such as network congestion or changes in user behavior.
  7. UE Detach:
    • When the UE detaches or ends the session, the PCF is notified. The PCF may release allocated resources and update charging information.
  8. Interworking with Charging System:
    • The PCF interacts with the Charging Function (CHF) to ensure accurate charging and billing for the user's data usage.

The 5G PCF call flow involves interactions with various other network functions, such as AMF, PCRF, SMF, and CHF. Additionally, the PCF relies on the use of policies and rules to manage the user's data sessions effectively. The dynamic nature of 5G networks allows for real-time adjustments to policies, enabling efficient resource utilization and a better user experience.