Content for  TS 23.401  Word version:  19.0.0

The PDN-GW may request for each PDN connection independently whether the MME shall report changes of ECGI/eNodeB ID/TAI (by using the "MS Info Change Reporting Action" parameter) and/or the UE entering/leaving a Presence Reporting Area (by using the "Presence Reporting Area Action" parameter) and/or whether the MME shall report changes of user CSG information (by using "CSG Information Reporting Action" parameter) to the PDN-GW. This reporting (any combination of "MS Info Change Reporting Action" and/or "Presence Reporting Area Action" and/or "CSG Information Reporting Action") may be controlled by the PDN-GW at the following procedures:

• Attach,
• Tracking Area Update (when inducing a Modify Bearer procedure to the PDN-GW),
• Inter-RAT Mobility to E-UTRAN (when inducing a Modify Bearer procedure to the PDN-GW),
• Dedicated bearer activation,
• PDN-GW initiated bearer modification with bearer QoS update,
• PDN-GW initiated bearer modification without bearer QoS update,
• UE requested PDN connectivity,
• UE requested bearer resource modification.

The "Presence Reporting Area Action" and "Presence Reporting Area Information" parameters apply to all procedures listed above but, within this specification, their usage has only been described in the message flows related with the Attach and the UE requested PDN connectivity procedures. The reporting of UE entering/leaving a Presence Reporting Area is further described in clause 5.9.2.2. The PDN-GW may also request the MME to stop any of the above mentioned types of reporting. The MME shall obey the last explicit instruction received from the PDN-GW or source MME. During both mobility management and session management procedures, the MME shall indicate to the PDN-GW the support of reporting location changes (using the MS Info Change Reporting support indication):

• If ECGI/eNodeB ID/TAI information is permitted to be sent to the PDN-GW according to MME operator's policy,
• If CSG information is permitted to be sent to the PDN-GW according to MME operator's policy.

The MME may be configured to report ECGI/eNodeB ID/TAI changes only when one or more E-RAB(s) are established. Otherwise the MME shall report ECGI/eNodeB ID/TAI changes as soon as detected. If the level of support changes during a mobility management procedure then the MME shall indicate the current level of support to the S-GW and shall in addition provide ECGI/eNodeB ID/TAI even if the PDN-GW has not requested this information. This could for example happen during MME change when the level of support indicated by the old MME is not the same as in the new MME. At change of Serving Node (MME/S4-SGSN), the old Serving Node provides the new serving node with "MS Info Change Reporting Action" as previously requested by the PDN-GW. The new Serving Node takes the "MS Info Change Reporting Action" immediately into account with the exception that, at mobility between a S4-SGSN and a MME, the new MME (respectively S4-SGSN) does not take into account the "MS Info Change Reporting Action" received from the S4-SGSN (respectively MME) but assumes that no location information change reporting is requested for the target RAT. At a change of RAT type between EUTRAN and UTRAN or between EUTRAN and GERAN, if location information change reporting is required in the target RAT, the PDN-GW shall request "MS Info Change Reporting Action" from the new Serving Node (MME or S4-SGSN). Upon inter-RAT mobility, if the target MME/S4-SGSN supports location information change reporting, the target MME/S4-SGSN shall include the User Location Information in the Create Session Request / Modify Bearer Request, regardless of whether location Information change reporting had been requested in the previous RAT by the PDN-GW. The PDN-GWPDN-GW shall not request the MME to report location changes if it has not received the indication for corresponding support from the MME. The following procedure shall be used for location change reports to the PDN-GWPDN-GW where the report is not combined with other mobility management or session management signalling. The procedure shall only apply when the MME has been explicitly requested to report location changes. The following procedure can be used for MO Exception Data Counter reporting where the report is not combined with other mobility management or session management signalling. The MME only includes the MO Exception data counter if the RRC establishment cause is set to "MO exception data" and the UE is accessing via the NB-IoT RAT. The MME maintains the MO Exception Data Counter for Serving PLMN Rate Control purposes (see clause 4.7.7.2). The MME may immediately send the MO Exception Data Counter to the Serving-GW. Alternatively, in order to reduce signalling, the MME may send the MO Exception Data Counter to the Serving-GW as described in TS 29.274. The SGW and PDN-GWPDN-GW indicate each use of this RRC establishment cause by the related counter on its CDR. Figure 5.9.2.1-1 represents the ECGI change triggering a report of change in ECGI, and/or the User CSG information change triggering a report of change in user CSG information. The Figure also shows the reporting of a TAI change and/or when a UE enters or leaves a Presence Reporting Area.

In some use cases policy control/charging decisions, such as QoS modification or charging rate change depend on whether the UE is located inside or outside a specific area of interest (Presence Reporting Area), and especially on whether the UE enters or leaves that specific area of interest. A Presence Reporting Area can be:

• Either a "UE-dedicated Presence Reporting Area", defined in the subscriber profile and composed of a short list of TAs/RAs, or eNodeBs and/or cells/SAs in a PLMN;
• Or a "Core Network predefined Presence Reporting Area", predefined in MME/SGSN and composed of a short list of TAs/RAs, or eNodeBs and/or cells/SAs in a PLMN.

The reporting of changes of UE presence in Presence Reporting Area is for a specific UE and is triggered as defined in TS 23.203. The PDN-GW may request to Start/Stop reporting of changes of UE presence for one or more Presence Reporting Area(s) by using the Presence Reporting Area Action parameter. For UE-dedicated Presence Reporting Areas, the reporting request (Start) shall contain the PRA identifier(s) and the list(s) of TAs/RAs, or eNodeBs and/or cells/SAIs composing the Presence Reporting Area(s). For Core Network predefined Presence Reporting Areas, the reporting request (Start) shall contain the PRA identifier(s). The request to Stop a reporting contains the PRA identifier(s). Each Core Network predefined Presence Reporting Area can be configured with a priority level in the MME/S4-SGSN. In order to prevent overload, the MME/S4-SGSN may set the reporting for one or more of the received Presence Reporting Area(s) to inactive under consideration of the priority configured for each of Core Network predefined Presence Reporting Area(s), while storing the reporting request for this Presence Reporting Area in the user context. Upon reception of a request for change of UE presence in Presence Reporting Area reporting, the MME/S4-SGSN shall report to the PDN-GW via the SGW the Presence Reporting Area Information comprising the PRA identifier(s) and indication(s) on whether the UE is inside or outside the Presence Reporting Area(s). If the UE is in ECM-IDLE state, the MME may either bring the UE into ECM-CONNECTED state, or, report based on the UE's last known location and when the UE was there. One or more Presence Reporting Area may be set for a given PDN connection at a time. The serving node if needed only sets the reporting of UE presence in a Presence Reporting Area to inactive when receiving the reporting request for this Presence Reporting Area. If the MME/S4-SGSN decides to set the reporting of UE presence in one or more of the received Presence Reporting Area(s) to inactive, the MME/S4-SGSN shall also report the inactive Presence Reporting Area(s). The MME/S4-SGSN shall notify the PDN-GW when the UE enters or leaves a Presence Reporting Area, and no notifications are sent for UE movements inside or outside a Presence Reporting Area. The report of the change of UE presence in Presence Reporting Area shall contain the Presence Reporting Area Information comprising the PRA identifier(s) and indication(s) on whether the UE is inside or outside the area(s). A report shall be sent if the UE presence is different to the last one reported. The MME/S4-SGSN may be configured with a PRA identifier which refers to a Set of Core Network predefined Presence Reporting Areas. The PDN-GW may request Start reporting for this Set of Presence Reporting Areas by only indicating this PRA identifier in the Presence Reporting Area Action. When the Presence Reporting Area(s) to be reported belong to a set of Core Network predefined Presence Reporting Areas in which the MME/S4-SGSN is requested to report on change of UE presence, the MME/S4-SGSN shall additionally add to the report the PRA identifier of the Set of Core Network predefined Presence Reporting Areas. Upon change of serving EPC node (MME, S4-SGSN), the PRA identifier(s) and if provided by the PDN-GW the list(s) of Presence Reporting Area elements are transferred for all PDN connections as part of MM Context information to the target serving node during the mobility procedure. If one or more Presence Reporting Area(s) was set to inactive, the target serving node may decide to reactivate one or more of the inactive Presence Reporting Area(s). The target serving node indicates per PDN connection to the corresponding PDN-GW the PRA identifier(s) and whether the UE is inside or outside the Presence Reporting Area(s) as well as the inactive Presence Reporting Area(s), if any.