Section: 4.16.2.1.2 AM Policy Association Modification with old PCF during AMF relocation
Content: This procedure is applicable to Case C. In this case, AMF relocation is performed without PCF change in handover procedure and registration procedure. Figure 4.16.2.1.2-1: AM Policy Association Modification with the old PCF during AMF relocation This procedure concerns both roaming and non-roaming scenarios. 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: 1. [Conditional] When the old AMF and the new AMF belong to the same PLMN, the old AMF transfers to the new AMF the AM Policy Association information including Policy Control Request Trigger(s) and the PCF ID. For the roaming case, the new AMF receives V-PCF ID. 2. Based on local policies, the new AMF decides to establish an AM Policy Association with the (V-)PCF and contacts the (V-)PCF identified by the PCF ID received in step 1. 3. The new AMF sends Npcf_AMPolicyControl_Update to the (V-)PCF to update the AM Policy Association with the (V-)PCF. The request may include the following information: Policy Control Request Trigger which has been met, Subscribed Service Area Restrictions (if updated), subscribed RFSP index (if updated) which are retrieved from the UDM during the update location procedure and may include access type and RAT, PEI, ULI, UE time zone, service network. The (V-)PCF updates the stored information provided by the old AMF with the information provided by the new AMF. In the non-roaming case, the PCF may subscribe to Analytics from NWDAF as defined in clause 6.1.1.3 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20]. If the PCF determines a change to policy counter status reporting is required, it may alter the subscribed list of policy counters using the Initial, Intermediate or Final Spending Limit Report Retrieval procedures as defined in clause 4.16.8. When AMF utilizes an NWDAF, it may add the NWDAF serving the UE identified by the NWDAF instance ID. Per NWDAF service instance the Analytics ID(s) are also included. 4. The (V-)PCF may update the policy decision based on the information provided by the new AMF and responds to the Npcf_AMPolicyControl_Update service operation providing access and mobility related policy information as defined in clause 6.5 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20]. If an AF has previously subscribed to request for allocation of service area coverage outcome event the (V-)PCF checks if reporting is needed, using the Policy Control Request Trigger that was met (see step 1) as input, then 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]. 5. The AMF deploys the access and mobility related policy information, which includes storing the Service Area Restrictions, provisioning Service Area Restrictions to the UE and provisioning the RFSP index, UE-AMBR, Service Area Restrictions 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.