Section: 4.16.12.1.2 UE Policy Association Modification with old PCF during AMF relocation
Content: This procedure addresses the scenario where a UE Policy Association Modification with the old PCF during AMF relocation. Figure 4.16.12.1.2-1: Policy Association Modification with the old PCF during AMF relocation This procedure addresses both roaming and non-roaming scenarios. In the non-roaming case the V-PCF is not involved. In the roaming case, the AMF interacts with the V-PCF and the V-PCF interacts with the H-PCF. 1. [Conditional] When the old AMF and the new AMF belong to the same PLMN, the old AMF transfers to the new AMF the UE Policy Association information including policy control request trigger(s) and the PCF ID(s). For the roaming case, the new AMF receives both V-PCF ID and H-PCF ID. 2. Based on local policies, the new AMF decides to re-use the UE policy association for the UE Context with the (V-)PCF and contacts the (V)-PCF identified by the PCF ID received in step 1. NOTE: The scenario that only the H-PCF is reused by the new AMF but the V-PCF is not reused is not considered in this Release. 3. The new AMF sends Npcf_UEPolicyControl_Update to the (V-)PCF to update the UE policy association with the (V-)PCF. If a Policy Control Request Trigger condition is met, the information matching the trigger condition may also be provided by the new AMF. In the roaming case, step 4 and 5 are executed, otherwise step 6 follows. 4. The V-PCF forwards the information received from new AMF in step 3 to the (H-)PCF. 5. The H-PCF replies to the V-PCF. In 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]. 6. The (V-)PCF updates the stored information provided by the old AMF with the information provided by the new AMF. The (V-)PCF sends a Npcf_UEPolicyControl Update Response to the AMF. 7. The (H-)PCF may create the UE policy container including UE policy information as defined in clause 6.6 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20]. In the case of roaming the H-PCF may include the UE policy container in the Npcf_UEPolicyControl UpdateNotify Request. 8. The V-PCF sends a response to H-PCF using Npcf_UEPolicyControl UpdateNotify Response. Steps 9, 10 and 11 are the same as steps 8, 9 and 10 of procedure UE Policy Association Establishment in clause 4.16.11.