Section: 5.9.1 Location Reporting Procedure
Content: This procedure is used by an MME to request the eNodeB to report where the UE is currently located when the target UE is in ECM-CONNECTED state. The need for the eNodeB to continue reporting ceases when the UE transitions to ECM-IDLE. This procedure may be used for services that require accurate cell identification (e.g. for emergency services, lawful intercept, charging). When Dual Connectivity is activated, the PSCell information is only reported if requested by the MME. In the case of satellite access for Cellular IoT, this procedure may be used by the MME to determine the TAI where the UE is geographically located. Figure 5.9.1-1: Location Reporting Procedure 1) The MME sends a Location Reporting Control message to the eNodeB. The Location Reporting Control message shall identify the UE for which reports are requested, the requested location information and may contain information such as reporting type. Requested location information is TAI+EGCI, and if requested by the MME, PSCell ID. Reporting type indicates whether the message is intended to trigger: - a single stand-alone report about the current Cell ID serving the UE; or - start the eNodeB to report whenever the UE changes cell. In addition, the MME shall be able to control whether or not the RAN reports changes in the UE's PSCell ID. NOTE 1: Requesting reports whenever the UE changes cell can increase signalling load on multiple interfaces. Requesting reports for changes in PSCell ID can further increase signalling load. Hence it is recommended that any such reporting is only applied for a limited number of subscribers. 2) The eNodeB sends a Location Report message informing the MME about the location of the UE which shall include the requested location information. If the MME requests UE location, in the case of satellite access for Cellular IoT, the eNodeB provides all broadcast TAIs to the MME as part of the ULI. The eNodeB also reports the TAI where the UE is geographically located if this TAI can be determined. The cell and TAI reporting by eNodeB refer to a fixed cell and fixed TA in which a UE is geographically located. As part of the User Location Information, eNodeB also reports one or more TACs for the Selected PLMN as described in TS 36.413[ Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 Application Protocol (S1AP) ]  [36], but it is not guaranteed that the UE is always located in one of these TACs. 3) The MME can send a Cancel Location Reporting message to inform the eNodeB that it should terminate location reporting for a given UE. This message is needed only when the reporting was requested for a reporting period. NOTE 2: Location reporting is transferred during X2 handover, although new control signalling is not transferred during an active handover.