4.2.1 UE-Initiated

29.2133GPPPolicy and charging control signalling flows and Quality of Service (QoS) parameter mappingRelease 17TS

4.2.1.1 AF located in the HPLMN

This clause is applicable if an IP-CAN Session is being released by the UE and the AF is located in the HPLMN.

Figure 4.2.1.1.1: UE-Initiated IP-CAN Session Termination – AF located in the HPLMN

In the following procedures, the V-PCRF is included to depict the roaming scenarios. H-PCRF acts as the PCRF for non-roaming UEs.

1. If case 2b applies (as defined in clause 4.0), the BBERF receives a request to remove the IP-CAN session. In case 2a, the request goes transparently through the BBERF. In all cases, the PCEF receives a request to remove the IP-CAN Session. The form of the Remove IP-CAN Session Request depends upon the type of the IP-CAN.

2. If case 2b applies (as defined in clause 4.0), the BBERF-initiated Gateway Control Session Termination procedure as defined in clause 4.4.4 (BBERF-Initiated Gateway Control Session Termination) is initiated.

3. For the non-roaming case, and for the case when the UE is roaming in a Home Routed scenario, the PCEF sends a CCR to the H-PCRF, indicating the IP-CAN Session termination. The PCEF requests the termination of the Gx session using the CC-Request-Type AVP set to the value TERMINATION_REQUEST. If the usage monitoring is enabled, the PCEF informs the H-PCRF about the resources that have been consumed by the user since the last report. If the Required-Access-Info AVP is included in any PCC Rule, the PCEF informs the H-PCRF about the access network information. If NAS-RAN-Cause feature is supported the PCEF informs the H-PCRF about the access network information and the failure cause(s), if available.

For the case when the UE is roaming in a Visited Access scenario, steps 3a~3b are executed instead of step 3:

3a. The PCEF sends a CCR to the V-PCRF, indicating the IP-CAN Session termination. The PCEF requests the termination of the Gx session using the CC-Request-Type AVP set to the value TERMINATION_REQUEST. If the usage monitoring is enabled, the PCEF informs the V-PCRF about the resources that have been consumed by the user since the last report. If the Required-Access-Info AVP is included in any PCC Rule, the PCEF informs the V-PCRF about access network information.

3b If there is an active TDF session between the TDF and the V-PCRF, for roaming UE with visited access, the TDF Session termination is initiated as defined in Section 4.6.2. For this case, the PCRF described in Section 4.6.2 acts as a V-PCRF.

3c. If congestion reporting is active for the user id and PDN id, for roaming UE with visited access, the V-PCRF initiates a UE context removal as defined in clause 4.8.5.

3d. The V-PCRF sends the CCR to the H-PCRF. If case 2b or case 1 applies and this is the last subsession associated with the S9 session, the V-PCRF sends a CCR to the H-PCRF to request the termination of the S9 session using the CC-Request-Type AVP set to the value TERMINATION_REQUEST. Otherwise, the V-PCRF sends a CCR to the H-PCRF with a CC-Request-Type AVP set to the value UPDATE_REQUEST and a Subsession-Enforcement-Info within which the Subsession-Operation AVP set to value TERMINATION to request the termination of the conresponding S9 subsession.

NOTE 1: If the usage monitoring is enabled on PCEF and/or TDF, the V-PCRF gathers the reports and provides them all to H-PCRF in the single CCR message.

4. The H-PCRF identifies the AF sessions that are bound to IP flows of the removed IP-CAN Session.

5. For the non-roaming case, and for the case when the UE is roaming in a Home Routed scenario, the H-PCRF acknowledges the Gx session termination by sending a CCA to the PCEF.

For the case when the UE is roaming in a Visited Access scenario, steps 5a~5c are executed instead of step 5:

5a. The H-PCRF acknowledges the S9 session or subsession termination by sending a CCA to the V-PCRF.

5b. The V-PCRF removes the information related to the terminated IP-CAN Session.

5c. The V-PCRF acknowledges the Gx session termination by sending a CCA to the PCEF.

6. The PCEF sends a response to the Remove IP-CAN Session Request. The form of the Remove IP-CAN Session Response depends upon the type of the IP-CAN. Step 6 may be executed in parallel with step 3 or 3a (as applicable).

7. If there is an activeTDF session between the TDF and the H-PCRF, for non-roaming UE/roaming UE with home routed access, the TDF Session termination is initiated as defined in Section 4.6.2.

NOTE 2: Step 7 can occur anytime after step 3.

For each AF session identified in step 4 as bound to the IP-CAN Session being removed, steps 7-11 are executed:

8. If congestion reporting is active for the user id and PDN id, for non-roaming UE or UE is roaming in home routed case, the H-PCRF initiates a UE context removal as defined in clause 4.8.5.

NOTE 3: Step 8 can occur anytime after step 3.

9. The H-PCRF indicates the session abort to the H-AF by sending an ASR to the H-AF.

10. The H-AF responds by sending an ASA to the H-PCRF.

11. The H-AF sends an STR to the H-PCRF to indicate that the session has been terminated.

12. The H-PCRF responds by sending an STA to the H-AF. If the provided PCC rules are related to an AF session associated with a sponsor, usage thresholds were provided by the H-AF earlier, and the H-PCRF has usage data that has not yet been reported to the H-AF, the H-PCRF informs the H-AF about the resources that have been consumed by the user since the last report. If the BBERF in step 2 or PCEF in step 3 reports the access network information and if the AF requested the H-PCRF to report access network information previously and/or the RAN-NAS-Cause feature is supported, the H-PCRF informs the H-AF about the access network information and/or RAN/NAS/TWAN/Untrusted WLAN failure cause(s) if available.

13. If this is the last IP-CAN session for this subscriber the Final Spending Limit Report Request as defined in clause 4.7.3 is sent. If any existing IP-CAN sessions for this subscriber require policy counter status reporting, the Intermediate Spending Limit Report Request as defined in clause 4.7.2 can be sent to alter the list of subscribed policy counters.

14. If case 2a applies (as defined in clause 4.0), the Gateway Control and QoS Rules Provision procedure as defined in clause 4.4.3 (Gateway Control and QoS Rules Provision) may be initiated to remove the QoS rules associated with the IP‑CAN session being terminated. This applies e.g. in case the Gateway Control Session remains to serve other IP‑CAN sessions.

Alternatively, if UE acquires a care of address (CoA) that is used for the S2c reference point and the H-PCRF determines that all QoS rules are to be removed and the Gateway Control Session to be terminated, the PCRF-initiated Gateway Control Session Termination procedure as defined in clause 4.4.4 (PCRF-Initiated Gateway Control Session Termination) is initiated. This applies e.g. in case the UE is detached and the CoA acquired by the UE is not used for any other IP‑CAN session.

15. The H-PCRF sends a cancellation notification request to the SPR if it has subscribed such notification. The H-PCRF stores the remaining usage allowance in the SPR if all IP-CAN sessions of the user to the same APN are terminated. Step 14 may be initiated any time after step 5 or 5a (as applicable).

16. The SPR sends a response to the H-PCRF.

NOTE 4: For steps 14 and 15: The details associated with the Sp reference point are not specified in this Release. The SPR’s relation to existing subscriber databases is not specified in this Release.

17. If the H-PCRF has provided traffic steering control information to the TSSF for the IP-CAN session, the H-PCRF initiates the St session termination procedure to the TSSF to remove the traffic steering control information associated to the UE IPv4 address and/or to the UE IPv6 prefix for the terminated IP-CAN session according to the subclause 4.9.3.

NOTE 5: Step 17 can be initiated any time after step 5.

4.2.1.2 AF located in the VPLMN

This clause is applicable only for the Visited Access scenario for the case when an IP-CAN Session is being released by the UE and the AF is located in the VPLMN.

Figure 4.2.1.2.1: UE-Initiated IP-CAN Session Termination – AF located in the VPLMN

If the AF resides in the VPLMN, the V‑PCRF proxies AF session signalling over S9 between the V-AF and the H‑PCRF.

1 In order to perform UE initiated IP-CAN Session Termination Procedures, step 1 through step 8: as specified in Figure 4.2.1.1.1: UE Initiated IP-CAN Session Termination – AF Located in the HPLMN are executed.

For each AF session identified in step 4 (Figure 4.2.1.1.1) as bound to the IP-CAN Session being removed steps 2-10 are executed:

2. The H-PCRF indicates the session abort to the V-AF in VPLMN by sending an ASR to the V-PCRF.

3. The V-PCRF proxies the ASR to the V-AF.

4. The V-AF responds by sending an ASA to the V-PCRF.

5. The V-PCRF proxies the ASA to the H-PCRF.

6. The V-AF sends an STR to the V-PCRF to indicate that the session has been terminated.

7. The V-PCRF proxies the STR to the H-PCRF.

8. The H-PCRF responds by sending an STA to the V-PCRF.

9. The V-PCRF proxies the STA to the V-AF.

10. Step 13 through step 16: as specified in Figure 4.2.1.1.1: UE Initiated IP-CAN Session Termination – AF Located in the HPLMN are executed, as needed.

NOTE: For steps 15 and 16: the details associated with the Sp reference point are not specified in this Release. The SPR’s relation to existing subscriber databases is not specified in this Release.