Content for  TS 23.402  Word version:  18.3.0

If dynamic PCC is deployed, the PDN-GW initiated Bearer Deactivation procedure may for example be triggered due to 'IP-CAN session Modification procedure', as defined in TS 23.203. In this case, the resources associated with the PDN connection in the PDN-GW are released. If requested by the Application Function (e.g. P-CSCF), the PCRF may also include a request to provide the User Location Info and/or the Time zone to the PDN-GW.

The PDN-GW sends a Delete Bearer Request message (EPS Bearer Identity, Cause) to the TWAN. This message can include an indication that all bearers belonging to that PDN connection shall be released.

In multi-connection mode, if all bearers belonging to a PDN connection are released, then the UE is informed of the PDN connection release by means of a WLCP PDN Disconnection Request (PDN Connection ID). The UE acknowledges the disconnection request.

In multi-connection mode, if a dedicated bearer is marked for deletion in step 2 and multiple WLCP bearers are used, the TWAN sends a WLCP Bearer Delete message with a list of bearer identities to be deleted. The UE acknowledges the Bearer Delete Request.

If supported by the TWAN, the TWAN specific resources may be released in the TWAN. The details of this step are out of the scope of 3GPP.

The TWAN deletes the bearer contexts related to the Delete Bearer Request, and acknowledges the bearer deactivation to the PDN-GW by sending a Delete Bearer Response (EPS Bearer Identity) message. Additionally, the Delete Bearer Response includes the TWAN Identifier as described in clause 16.1.7, the Timestamp of this TWAN-Identifier and the UE Time Zone.

In the case where the resources corresponding to the PDN connection are released in PDN-GW, the PDN-GW informs the 3GPP AAA Server/HSS of the PDN disconnection. 8. The PDN-GW deletes the bearer context related to the deactivated S2a bearer. If the dedicated bearer deactivation procedure was triggered by receiving a PCC decision message from the PCRF, the PDN-GW indicates to the PCRF whether the requested PCC decision was successfully enforced by completing the PCRF-initiated IP-CAN Session Modification procedure or the PCEF initiated IP-CAN Session Modification procedure as defined in TS 23.203, proceeding after the completion of IP-CAN bearer signalling. If requested by the PCRF in step 1, the PDN-GW provides the User Location Information, that contains the TWAN Identifier and/or UE Time Zone that will be forwarded to the Application Function as defined in TS 23.203.

If dynamic PCC is deployed, the PCRF sends a PCC decision provision (QoS policy) message to the PDN-GW. If the Application Function (e.g. P-CSCF) requests it, the PCRF may also include a request to provide the User Location Information and/or the Time zone. This corresponds to the initial steps of the PCRF-Initiated IP-CAN Session Modification procedure or to the PCRF response in the PCEF initiated IP-CAN Session Modification procedure as defined in TS 23.203, up to the point that the PDN-GW requests IP-CAN Bearer Signalling. If dynamic PCC is not deployed, the PDN-GW may apply local QoS policy.

The PDN-GW uses this QoS policy to determine that a service data flow shall be aggregated to or removed from an active S2a bearer or that the authorized QoS of a service data flow has changed. The PDN-GW generates the TFT and updates the S2a bearer QoS to match the traffic flow aggregate. The PDN-GW then sends the Update Bearer Request (EPS bearer Identity, EPS bearer QoS, TFT) message to the trusted WLAN access network.

The TWAN sends WLCP Bearer Update Request with a list of modified bearers (Bearer ID, TFT, Bearer QoS information) to the UE if multiple WLCP bearers are used between the UE and TWAG. The UE stores and uses the updated TFT or Bearer QoS information for each Bearer Id. The UE acknowledges the WLCP Bearer Update Request by sending WLCP Bearer Update Response.

A TWAN specific resource allocation/modification procedure may be executed in this step. The details of this step are out of the scope of 3GPP.

The TWAN uses the uplink packet filter (UL TFT) to determine the mapping of traffic flows to the S2a bearer and acknowledges the S2a bearer modification to the PGW by sending an Update Bearer Response (EPS bearer Identity) message. Additionally, the Update Bearer Response includes the current TWAN Identifier as described in clause 16.1.7 and the UE Time Zone.

If the Bearer modification procedure was triggered by a PCC Decision Provision message from the PCRF, the PDN-GW indicates to the PCRF whether the requested PCC decision (QoS policy) could be enforced or not by sending a Provision Ack message allowing the completion of the PCRF-Initiated IP-CAN Session Modification procedure or the PCEF initiated IP-CAN Session Modification procedure as defined in TS 23.203, after the completion of IP-CAN bearer signalling. If requested by the PCRF in step1, the PDN-GW provides the User Location Information that contains the TWAN identifier and/or UE Time Zone that will be forwarded to the Application Function as defined in TS 23.203.

The HSS updates the User Profile as specified in clause 12.2.1.

If the QCI and/or ARP and/or subscribed APN-AMBR has been modified and there is a related active PDN connection with the modified QoS Profile, the trusted WLAN access network sends the Modify Bearer Command (EPS bearer Identity, EPS bearer QoS, APN AMBR) message to the PDN-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.

If PCC infrastructure is deployed, the PDN-GW informs the PCRF about the updated EPS bearer QoS. The PCRF sends the 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. 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.

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 S2a 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 TWAN.

The TWAN sends WLCP Bearer Update Request with a list of modified bearers (Bearer ID, TFT, Bearer QoS information) to the UE if multiple WLCP bearers are used between the UE and TWAG. The UE stores and uses the updated TFT or Bearer QoS information for each Bearer Id. The UE acknowledges the WLCP Bearer Update Request by sending a WLCP Bearer Update Response.

A TWAN specific resource allocation/modification procedure may be executed in this step. The details of this step are out of the scope of 3GPP.

The TWAN acknowledges the bearer modification to the PDN-GW by sending an Update Bearer Response (EPS bearer Identity) message. If the bearer modification fails the PDN-GW deletes the concerned S2a Bearer.

The PDN-GW indicates to the PCRF whether the requested PCC decision was enforced or not by sending a Provision Ack message.