Section: 5.4.2.2 HSS Initiated Subscribed QoS Modification
Content: The HSS Initiated Subscribed QoS Modification for a GTP-based S5/S8 is depicted in figure 5.4.2.2-1. Figure 5.4.2.2-1: HSS Initiated Subscribed QoS Modification NOTE 1: For a PMIP-based S5/S8, procedure steps (A) and steps (B) are defined in TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [2]. Steps 3, 4, 5, 7 and 8 concern GTP based S5/S8. 1. The HSS sends an Insert Subscriber Data (IMSI, Subscription Data) message to the MME. The Subscription Data includes EPS subscribed QoS (QCI, ARP) and the subscribed UE-AMBR and APN-AMBR. 1a. The MME updates the stored Subscription Data and acknowledges the Insert Subscriber Data message by returning an Insert Subscriber Data Ack (IMSI) message to the HSS (see clause 5.3.9.2). 2a If only the subscribed UE-AMBR has been modified, the MME calculates a new UE-AMBR value as described in clause 4.7.3 and may then signal a modified UE-AMBR value to the eNodeB by using S1-AP UE Context Modification Procedure. The HSS Initiated Subscribed QoS Modification Procedure ends after completion of the UE Context Modification Procedure. 2b. If the QCI and/or ARP and/or subscribed APN-AMBR has been modified and there is related active PDN connection with the modified QoS Profile the MME sends the Modify Bearer Command (EPS Bearer Identity, EPS Bearer QoS, APN-AMBR) message to the Serving GW. The EPS Bearer Identity identifies the default bearer of the affected PDN connection. The EPS Bearer QoS contains the EPS subscribed QoS profile to be updated. 3. The Serving GW sends the Modify Bearer Command (EPS Bearer Identity, EPS Bearer QoS, APN-AMBR) message to the PDN GW. 4. If PCC infrastructure is deployed, the PDN GW informs the PCRF about the updated EPS Bearer QoS and APN-AMBR. The PCRF sends new updated PCC decision to the PDN GW. This corresponds to the PCEF-initiated IP-CAN Session Modification procedure as defined in TS 23.203[ Policy and charging control architecture ]  [6]. The PCRF may modify the APN-AMBR and the QoS parameters (QCI and ARP) associated with the default bearer in the response to the PDN GW as defined in TS 23.203[ Policy and charging control architecture ]  [6]. 5. The PDN GW modifies the default bearer of each PDN connection corresponding to the APN for which subscribed QoS has been modified. If the subscribed ARP parameter has been changed, the PDN GW shall also modify all dedicated EPS bearers having the previously subscribed ARP value unless superseded by PCRF decision. The PDN GW then sends the Update Bearer Request (EPS Bearer Identity, EPS Bearer QoS, TFT, APN-AMBR) message to the Serving GW. NOTE 2: As no PTI is included the MME use protocol specific details, as described in TS 29.274[ 3GPP Evolved Packet System (EPS); Evolved General Packet Radio Service (GPRS) Tunnelling Protocol for Control plane (GTPv2-C); Stage 3 ]  [43], to determine if the Update Bearer Request was triggered by this procedure or not. 6. If the QCI and/or ARP parameter(s) have been modified, steps 3 to 10, as described in clause 5.4.2.1, Figure 5.4.2.1-1, are invoked. If neither the QCI nor the ARP have been modified, but instead only the APN-AMBR was updated, steps 3 to 8, as described in clause 5.4.3, Figure 5.4.3-1, are invoked. 7. The Serving GW acknowledges the bearer modification to the PDN GW by sending an Update Bearer Response (EPS Bearer Identity, User Location Information (ECGI)) message. If the bearer modification fails the PDN GW deletes the concerned EPS Bearer. 8. The PDN GW indicates to the PCRF whether the requested PCC decision was enforced or not by sending a Provision Ack message.