Section: 4.16.2.2 AM Policy Association Modification initiated by the PCF
Content: The AM Policy Association modification procedure may be initiated by an internal PCF event or by PCF obtaining pertinent analytics information from an NWDAF. The following procedure is applicable to AM Policy Association modification due to Case B. Figure 4.16.2.2-1: AM Policy Association Modification initiated by the PCF The procedure driven by a PCF internal event applies to both roaming and non-roaming scenarios and when driven by NWDAF or CHF, applies only to non-roaming scenarios. An AM Policy Association is established, with the V-PCF in case of roaming or with the PCF in a non-roaming case as described in clause 4.16.1.2 before this procedure is triggered. In the non-roaming case the role of the V-PCF is performed by the PCF. For the roaming scenarios, the V-PCF interacts with the AMF. NOTE: The V-PCF/PCF stores the access and mobility related policy information provided to the AMF. 1. [Conditional] The PCF determines internally that the new status of the UE context requires new policies, potentially triggered by an AF as described in clause 4.15.6.9 or by a notification from the UDR or optionally, the CHF provides a Spending Limit Report to the PCF as described in clause 4.16.8. This may be triggered by obtaining pertinent analytics information from an NWDAF as described in clause 6.1.1.3 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20]. 2. The (V-)PCF in case of roaming and PCF in a non-roaming case makes a policy decision. The PCF may also decide to subscribe to a new Analytics ID from NWDAF as described in clause 6.1.1.3 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20]. 3. The (V-)PCF in the roaming case and the PCF in a non-roaming case sends Npcf_AMPolicyControl_UpdateNotify including AM Policy Association ID associated with the SUPI defined in TS 29.507[ 5G System; Access and Mobility Policy Control Service; Stage 3 ]  [32]. The policy update may include Service Area Restrictions, UE-AMBR, RFSP index value and RFSP in Use Validity Time, access stratum time distribution indication, Uu time synchronization error budget, clock quality detail level and optionally clock quality acceptance criteria. If an AF has previously subscribed to event request for allocation of service area coverage outcome in step 1, the (V-)PCF checks if the allocated service area coverage was changed and sends a respective notification to the AF using Npcf_AMPolicyAuthorization_Notify as defined in clause 6.1.3.18 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20]. 4. The AMF deploys and stores the updated access and mobility related policy information, which includes storing the Service Area Restrictions and Policy Control Request Trigger of AM Policy Association, provisioning of the Service Area Restrictions to the UE, provisioning the RFSP index, UE-AMBR, Service Area Restrictions to the NG-RAN, optionally the access stratum time distribution indication, Uu time synchronization error budget, clock quality detail level and optionally clock quality acceptance criteria to the NG-RAN and request for notification of SM Policy association establishment and termination to a list of (DNN, S-NSSAI)(s) together with PCF for the UE binding information.