Feature Description
PCF integrates with AMF through the Access and Mobility Policy Control Service by transmitting the access control and mobility management-related policies to the AMF. With this integration, PCF, and AMF interact and exchange information through the following procedures:
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The PCF creates and updates the policies, and deletes the policy association depending on the request that it receives from AMF during the UE registration.
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The PCF notifies the AMF when a policy that AMF has subscribed to is updated. Similarly, AMF is also notified when a policy context is deleted for a UE.
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Depending on the event triggers that PCF has subscribed to, AMF takes the appropriate actions such as update the location procedure when the Service Area Restriction change triggers occur. The Service Area Restriction change is triggered only when a location change happens or the UE is changed in the Presence Reporting Area (PRA).
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During the PCF-AMF communication, if the PCF accumulates session information that is stale which means AMF has a more recent version of the session, or the session in PCF is no longer valid, then PCF purges the stale sessions.
In a reference point representation, a point-to-point reference point defines the interactions between the NFs. The PCF communicates with AMF over N15, and with SMF over N7.

Th PCF-AMF framework is compliant with the definitions of 3GPP TS 23.502 [3], 3GPP TS 23.503 [4], and 3GPP TS 29.507.