Section: 4.15.6.9.2 Processing AF requests to influence access and mobility management policies targeting an individual UE
Content: This procedure is used for individual UEs when the request shall be applied independently of conditions related to the application traffic. Depending on the AF deployment (see clause 6.2.10 of TS 23.501[ System architecture for the 5G System (5GS) ]  [2]), the AF may interact with NFs of the Core Network either directly or via the NEF. The procedure for the direct case is described in Figure 4.15.6.9.2-1, while the procedure for the NEF-mediated case is described in Figure 4.15.6.9.2-2. Figure 4.15.6.9.2-1: Handling an AF request targeting an individual UE without using NEF This procedure concerns only non-roaming scenarios, i.e. to cases where the involved entities serving the UE (AF, PCF, BSF, AMF) belong to the home PLMN. 1. An AM Policy Association is established for a UE as described in clause 4.16.1. 2a. The AF searches the PCF for the UE using Nbsf_Management_Subscribe with SUPI or GPSI as input, indicating that it is searching for the PCF that handles the AM Policy Association of the UE. 2b. The BSF provides to the AF the identity of the PCF for the UE for the requested SUPI or GPSI via an Nbsf_Management_Notify operation. If a matching entry already exists in the BSF when step 2a is performed, this shall be immediately reported to the AF. 2c. The AF sends to the PCF for the UE its request for influencing the access and mobility management policy of the UE (identified by SUPI or GPSI) using Npcf_AMPolicyAuthorization (optionally providing a timer on how long this policy shall last, in which case the system behaviour upon expiration of this timer is as specified in TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20]). As part of the Npcf_AMPolicyAuthorization request, the AF may subscribe (within the Create and Update operations) or unsubscribe (within the Delete operation) to relevant events specified in clause 6.1.3.18 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20], e.g. events related to change of service area coverage. 3. The PCF takes a policy decision and then an AM Policy Association Modification procedure initiated by the PCF for the UE may be performed as described in clause 4.16.2.2. If the AF has subscribed to access and mobility management related events (i.e. request for service area coverage outcome) in step 2, the PCF reports the event (i.e. outcome of the request for service area coverage) to the AF. Figure 4.15.6.9.2-2: Handling an AF request targeting an individual UE using NEF This procedure concerns only non-roaming scenarios, i.e. to cases where the involved entities serving the UE (AF, NEF, PCF, BSF, AMF) belong to the home PLMN, or the AF belongs to a third party with which the home PLMN has an agreement. 1. An AM Policy Association is established for a UE as described in clause 4.16.1. 2a. The AF sends to NEF its request for influencing the access and mobility management policy of the UE (identified by GPSI) using Nnef_AMPolicyAuthorization (optionally providing a timer on how long this policy shall last, in which case the system behaviour upon expiration of this timer is as specified in TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20]). As part of the Nnef_AMPolicyAuthorization request, the AF may request to subscribe (within the Create and Update operations) or unsubscribe (within the Delete operation) for relevant events specified in clause 6.1.3.18 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20], e.g. events for request for service area coverage outcome. The NEF stores the request and sends a response to the AF. 2b. The NEF searches the PCF for the UE using Nbsf_Management_Subscribe with SUPI as input parameter, indicating that it is searching for the PCF that handles the AM Policy Association of the UE. 2c. The BSF provides to the NEF the identity of the PCF for the UE for the requested SUPI via an Nbsf_Management_Notify operation. If a matching entry already exists in the BSF when step 2b is performed, this shall be immediately reported to the NEF. 2d. The NEF sends to PCF for the UE the request for influencing the access and mobility management policy of the UE (identified by SUPI) using Npcf_AMPolicyAuthorization (having potentially translated GPSI to SUPI via UDM). As part of the Npcf_AMPolicyAuthorization request, the NEF may subscribe or unsubscribe (according to what the AF requested in step 2a) for relevant events specified in clause 6.1.3.18 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20], e.g. events for change of service area coverage. 2e. The NEF informs the AF about events to which the AF has potentially subscribed (i.e. events for change of service area coverage) using Nnef_AMPolicyAuthorization_Notify. 3. The PCF takes a policy decision and then an AM Policy Association Modification procedure initiated by the PCF for the UE may be performed as described in clause 4.16.2.2. If the AF has subscribed to access and mobility management related events i.e. request for service area coverage outcome in step 2, then the PCF reports the event (i.e. outcome of the request for service area coverage) to the AF as described in clause 4.16.2.2.