Section: 4.16.14.2.1 Management of access and mobility related policy information at start and stop of application traffic
Content: This procedure applies when the AF provides a service coverage area or the indication of high throughput associated with the Application Identifer(s). Figure 4.16.14.2.1-1: Management of access and mobility related policy information at start and stop of application traffic 1. The AMF establishes an AM Policy Association for retrieving access and mobility related policy information, e.g. RFSP index value, as described in clause 4.16.1.2. 2. If the access and mobility related policy information depends on the application in use, then depending on operator policies in the PCF, the PCF may subscribe to the BSF, then step 3 follows, or provides its PCF binding information to the AMF in step 1 with the indication to be notified about the PCF for the PDU Session for a DNN, S-NSSAI, then step 4 follows. 3. The PCF for the UE determines that access and mobility related policy information (e.g. RFSP index value) depends on the detection of one or more application(s) in use, the DNN, S-NSSAI used to access each Application Id is configured in the PCF or retrieved from the UDR as part of the Application Data Set, then subscribes to the BSF to be notified when a PCF for the PDU Session for this SUPI is registered in the BSF, by invoking Nbsf_Management_Subscribe (SUPI, list of (DNN, S-NSSAI)(s)). Steps 4 and 5 are repeated for each PCF registered for a PDU Session to a (DNN, S-NSSAI) included in the Nbsf_Management. 4. The SMF establishes a SM Policy Association as described in clause 4.16.4. The allocated UE address/prefix, SUPI, DNN, S-NSSAI and the PCF address is registered in the BSF, as described in clause 6.1.1.2.2 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20]. 5a. If the PCF for the UE subscribed to the BSF, then the BSF notifies that a PCF for the PDU Session is registered in the BSF, by invoking Nbsf_Management_Notify (DNN, S-NSSAI, UE address(es), PCF address, PCF instance id, PCF Set ID, level of binding). When there are multiple PDU Sessions to the same (DNN, S-NSSAI) the BSF provides multiple notification to the PCF. 5b. If the PCF for the UE sent the request to notify that a PCF for the PDU Session is available to the AMF in step 1, then the PCF for the PDU Sessions sends Npcf_PolicyAuthorization_Notify (EventID set to SM Policy Association established, UE address, PCF address, PCF instance is, PCF Set ID) to the PCF indicated in the PCF binding information provided by the SMF. 6. The PCF for the UE subscribes to notifications of event "start/stop of application traffic" 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], using Npcf_PolicyAuthorization_Subscribe (UE address, EventId, EventFilter set to "list of Application Identifiers") to the PCF for the PDU Session to the DNN, S-NSSAI. The PCF for the PDU Session then generates PCC Rules including the Application Identifier in the SDF template, if there are multiple Application Identifiers included in the Npcf_PolicyAuthorization, the PCF generates PCC Rules for each Application Identifier. The response includes the NotificationCorrelationId. 7. The PCF installs PCC Rules and the Policy Control Request Trigger to detect "start/stop of application traffic" in the SMF. 8. The SMF detects that the Policy Control Request Trigger is met, then reports the start/stop of application traffic to the PCF serving the PDU Session. 9. The PCF for the UE is notified on the start/stop of application traffic by Npcf_PolicyAuthorization_Notify (NotificationCorrelationId, EventId set to "start/stop of application traffic", EventInformation including the ApplicationId). When the reporting of start and stop of a list of Application(s) was requested, the PCF for the PDU Session provides multiple notification to the PCF for the UE. 10. The PCF checks operator policies and then may change access and mobility related policy information (e.g. RFSP index value) based on the reporting of start/stop of application traffic. 11. The SM Policy Association is terminated as described in clause 4.16.6. The allocated UE address/prefix, SUPI, DNN, S-NSSAI and the PCF address are deregistered in the BSF. 12a. If the PCF for the UE subscribed to the BSF, then the BSF notifies that the PCF serving a PDU Session is deregistered in the BSF, by invoking Nbsf_Management_Notify (Binding Identifier for the PDU Session). 12b. If the PCF for the UE sent the request to notify that a PCF for the PDU Session is available to the AMF in step 1, then the PCF for the PDU Session sends Npcf_PolicyAuthoritation_Notify ((EventID set to SM Policy Association termination, Notification Correlation Id). NOTE: The PCF for the UE may subscribe to the notifications of newly registered PCF for the PDU Session and subscribe to the "start/stop of application traffic detection" events for multiple applications with different application identifiers. When PCF receives the notifications for multiple applications, the PCF for the UE can determine which access and mobility related policy information to apply based on local configuration and operator policy.