5.16 MME-initiated procedure on UE’s CSG membership change

23.4013GPPGeneral Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) accessRelease 18TS

If the UE is in ECM-CONNECTED state and connected via a CSG cell and the MME detects that the UE’s CSG membership to that cell has expired, the MME shall send an S1AP UE CONTEXT MODIFICATION REQUEST message to the eNodeB which includes an indication that the CSG membership of the UE has expired. The eNodeB receiving this indication may initiate a handover to another cell. If the UE is not handed over the eNodeB should initiate the S1 release procedure with an appropriate cause. The MME initiates S1 release after a configurable time if the UE is not handed over or released by the CSG cell. If the CSG membership expires for a UE with ongoing emergency bearer service, no indication that the CSG membership of the UE has expired is sent to the eNodeB and the MME shall deactivate all non-emergency PDN connections.

If the UE is in ECM-CONNECTED state and connected via a hybrid cell and the MME detects that the UE’s CSG membership to that cell has changed or expired, and the CSG Information Reporting Action indicates User CSG Information shall be reported to the P‑GW then the MME shall modify the last known CSG membership and send a Change Notification message to the Serving GW with User CSG Information to indicate the CSG membership change. The Serving GW shall send the Change Notification message with the User CSG Information to the PDN GW. The MME shall also send the S1AP UE CONTEXT MODIFICATION REQUEST message to the eNodeB which includes an indication of whether the UE is a CSG member. Based on this information the eNodeB may perform differentiated treatment for CSG and non-CSG members. MME shall release the impacted LIPA PDN connection if the LIPA CSG authorization data for this CSG cell is no longer valid due to UE’s CSG membership changed or expired.