Content for  TS 23.401  Word version:  18.4.0

The UE sends a Request Bearer Resource Modification (LBI, PTI, EPS Bearer Identity, QoS, TAD, Protocol Configuration Options) message to the MME. If the UE was in ECM-IDLE mode, this NAS message is preceded by the Service Request procedure. The TAD indicates one requested operation (add, modify, or delete packet filters). If traffic flows are added, the TAD includes the packet filter(s) (consisting of the packet filter information including packet filter precedence, but without a packet filter identifier) to be added. The UE also sends the QCI requested and GBR, if applicable, for the added traffic flows. If the UE wants to link the new packet filter(s) to an existing packet filter to enable the usage of existing bearer resources for the new packet filter(s), the UE shall provide an existing packet filter identifier together with the new packet filter(s). If the new packet filter(s) are not linked to an existing packet filter the UE shall provide at least one UL packet filter in the TAD. If a downlink only traffic flow(s) is to be added the UE shall provide an UL packet filter that effectively disallows any useful packet flows (see clause 15.3.3.4 of TS 23.060 for an example of such packet filter). If the UE wants to change the GBR in addition, the UE includes the GBR requirement of the EPS Bearer. The TAD is released when the procedure is completed. When only requesting for a modification of GBR (i.e. decrease or increase), the TAD shall include the existing packet filter identifier(s) for which the GBR change request applies to. The UE includes the GBR requirement of the EPS Bearer. The TAD is released when the procedure is completed. When requesting for a modification of packet filter(s) (e.g. change of port number), the TAD shall include packet filter identifier(s) for which the change request applies to together with the changed packet filter information. If the UE requests for deletion of traffic flows, the TAD includes the packet filter identifier(s) to be deleted. If the packet filters to be deleted were mapped to a GBR Bearer, the UE includes the new GBR requirement of the EPS Bearer. The UE sends the Linked Bearer Id (LBI) only when the requested operation is add, to indicate to which PDN connection the additional bearer resource is linked to. The EPS Bearer Identity is only sent when the requested operation is modify or delete. The Procedure Transaction Id is dynamically allocated by the UE for this procedure. The UE should ensure as far as possible that previously used PTI values are not immediately reused. The PTI is released when the procedure is completed. Protocol Configuration Options may be used to transfer application level parameters between the UE and the PDN-GW (see TS 23.228), and are sent transparently through the MME and the Serving-GW. If the PDN-GW indicated support for the 3GPP PS data off feature during PDN connection setup, the UE shall include in the PCO the 3GPP PS Data Off Support Indication, which indicates whether the user has activated or deactivated 3GPP PS Data Off.

The MME sends the Bearer Resource Command (IMSI, LBI, PTI, EPS Bearer Identity, QoS, TAD, Protocol Configuration Options) message to the selected Serving-GW. The MME validates the request using the Linked Bearer Id. The same Serving-GW address is used by the MME as for the EPS Bearer identified by the Linked Bearer Id received in the Request Bearer Resource Modification message.

The Serving-GW sends the Bearer Resource Command (IMSI, LBI, PTI, EPS Bearer Identity, QoS, TAD, Protocol Configuration Options) message to the PDN-GW. The Serving-GW sends the message to the same PDN-GW as for the EPS Bearer identified by the Linked Bearer Id.

The PDN-GW may either apply a locally configured QoS policy, or it may interact with the PCRF to trigger the appropriate PCC decision, which may take into account subscription information. This corresponds to the beginning of a 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. When interacting with PCRF, the PDN-GW provides to the PCRF the content of the TAD and, if applicable, the GBR change (increase or decrease) associated with the packet filter information contained in the TAD. The GBR change is either calculated from the current Bearer QoS and the requested Bearer QoS from the UE, or set to the requested GBR if the TAD indicates an add operation and no EPS Bearer Identity was received. If the TAD indicates an add operation, the requested QCI is also provided to the PCRF unless an existing packet filter identifier is provided together with the new packet filter. The PCC decision provision message may indicate that User Location Information and/or UE Time Zone information is to be provided to the PCRF as defined in TS 23.203. If the TAD operation is modify, delete, a request for changing the GBR, or add with a link to existing packet filter(s), then the PDN-GW provides to the PCRF the SDF filter identifier(s), previously assigned on Gx, that correspond to the received packet filter identifiers of the EPS bearer indicated by the received EPS bearer identity. If the PDN-GW detects that the 3GPP PS Data Off UE Status has changed, the PDN-GW shall indicate this event to the charging system for offline and online charging. If the 3GPP PS Data Off UE Status indicates that 3GPP PS Data Off is activated for the UE, the PDN-GW shall enforce the PCC rules for downlink traffic to be applied when 3GPP PS Data Off is activated, as described in TS 23.203.

If the request is accepted, either the Dedicated Bearer Activation Procedure (according to clause 5.4.1), the PDN-GW Initiated Bearer Deactivation Procedure (according to clause 5.4.4.1) or one of the Bearer Modification Procedures (according to clause 5.4.2.1 or 5.4.3) is invoked. The PTI allocated by the UE is used as a parameter in the invoked Dedicated Bearer Activation Procedure, the PDN-GW Initiated Bearer Deactivation Procedure or the Bearer Modification Procedure to correlate it to the UE Requested Bearer Resource Modification Procedure. This provides the UE with the necessary linkage to what EPS Bearer to be used for the new traffic flow aggregate. The PDN-GW shall not modify the QoS parameters requested by the UE. The PDN-GW inserts, modifies or removes packet filter(s) corresponding to the TAD into the TFT for the EPS bearer. If PCC is in use, the PDN-GW uses the service data flow filters as specified in the resulting PCC rule(s). The PDN-GW validates the state of the TFT settings of the PDN connection as defined in clause 15.3.0 of TS 23.060. If after the execution of all TAD operations the TFT of the dedicated EPS bearer contains only packet filters for the downlink direction, the PDN-GW shall add a packet filter which effectively disallows any useful packet flows in uplink direction (see clause 15.3.3.4 of TS 23.060 for an example of such a packet filter) to the TFT. When a new packet filter is inserted into a TFT, the PDN-GW assigns a new packet filter identifier which is unique within the TFT. The PDN-GW maintains the relation between the SDF filter identifier in the PCC rule received from the PCRF and the packet filter identifier of the TFT of this EPS bearer. If all of the packet filter(s) for a dedicated EPS bearer have been removed from the TFT, the PDN-GW performs the PDN-GW Initiated Bearer Deactivation Procedure. If the requested QoS is not granted (i.e. the requested QoS cannot be accepted or resources could not be allocated), or the resulting TFT settings of the PDN connection does not pass the validation, then the PDN-GW sends a Bearer Resource Failure Indication (with a cause indicating the reason why the request failed or was rejected) message, which shall be delivered to the UE.

If the PDN-GW interacted with the PCRF in step 4, the PDN-GW indicates to the PCRF whether the PCC decision could be enforced or not. This corresponds to the completion of 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 the PDN-GW indicates User Location Information and/or UE Time Zone Information to the PCRF as defined in TS 23.203.

The Master eNodeB sends a E-RAB Modification Indication message (eNodeB address(es) and TEIDs for downlink user plane for all the EPS bearers, CSG Membership Information, Secondary RAT usage data) to the MME. The Master eNodeB indicates for each bearer whether it is modified or not. If the PLMN has configured secondary RAT usage reporting and the eNodeB has Secondary RAT usage data to report, the Secondary RAT usage data is included. The eNodeB shall include the ECGI and, if Dual Connectivity is activated for the UE, the PSCell ID, in the E-RAB Modification Indication message. If the Secondary eNodeB is a hybrid access eNodeB, the Master eNodeB includes the CSG Membership Information for the SCG bearer(s) in the E-RAB Modification Indication message. The MME determines the CSG membership based on the CSG Membership Information as specified in TS 36.300, but does not update the User CSG Information in the Core Network. A failure of the CSG Membership Information verification does not impact the E-UTRAN initiated E-RAB modification procedure.

The MME sends a Modify Bearer Request (eNodeB address(es) and TEIDs for downlink user plane for all the EPS bearers, ISR Activated, User Location Information, PSCell ID, Secondary RAT usage data and indication to send it to PDN-GW) message per PDN connection to the Serving-GW, only for the affected PDN connections. If ISR was activated before this procedure, MME should maintain ISR. The UE is informed about the ISR status in the Tracking Area Update procedure. If the Serving-GW supports Modify Access Bearers Request procedure and if there is no need for the SGW to send the signalling to the PDN-GW, the MME may send a Modify Access Bearers Request (eNodeB address(es) and TEIDs for downlink user plane for all the EPS bearers, ISR Activated) to the Serving-GW to optimise the signalling. If the MME received Secondary RAT usage data in step 1, the MME shall include it in this message. If the MME received PSCell ID in step 1, the MME shall include it in this message. If Secondary RAT usage data was included and if PGW secondary RAT usage data reporting is active, the Serving-GW shall send Modify Bearer Request (Secondary RAT usage data) message to the PDN-GW for each PDN connection. The PDN-GW responds with Modify Bearer Response message to the Serving-GW.

The Serving-GW returns a Modify Bearer Response (Serving-GW address and TEID for uplink traffic) message to the MME as a response to a Modify Bearer Request message, or a Modify Access Bearers Response (Serving-GW address and TEID for uplink traffic) as a response to a Modify Access Bearers Request message. The Serving-GW starts sending downlink packets to the eNodeB using the newly received address and TEID.

In order to assist the reordering function in the Master eNodeB and/or Secondary RAN nodes, for the bearers that are switched between Master eNodeB and Secondary RAN nodes, the Serving-GW shall send one or more "end marker" packets on the old path immediately after switching the path as defined in clause 10.1.2.2 of TS 36.300.

The MME confirms the E-RAB modification with the E-RAB Modification Confirm (CSG Membership Status) message. The MME indicates for each bearer whether it was successfully modified, kept unmodified or already released by the EPC as defined in TS 36.413. For the EPS bearers that have not been switched successfully in the core network, it is the MME decision whether to maintain or release the corresponding EPS bearers. The eNodeB uses the CSG Membership Status to decide on further actions, as specified in TS 36.300.

The addition of an hybrid HeNB as the SeNodeB is triggered, providing the CSG-ID and the CSG Membership Information to the MeNodeB.

The Master eNodeB sends UE Context Modification Indication message to the MME, which includes the CSG Membership Information of the SeNodeB.

The MME verifies the CSG membership based on the provided CSG Membership Information as specified in TS 36.300, but does not update the User CSG Information in the Core Network. A failure of the CSG Membership Information verification does not impact the E-UTRAN UE Context Modification procedure.

The MME confirms the UE Context Modification Indication with the UE Context Modification Confirm (CSG Membership Status) message. If CSG Membership Information was not present in the UE Context Modification Indication message, the MME can not perform CSG Membership Information verification and does not provide CSG Membership Status in the UE Context Modification Confirm message.

If the CSG Membership Status returned by the MME is different from what was reported by the UE, the eNodeB may decide on further actions.