Content for  TS 23.273  Word version:  18.5.0

Steps 1-21 for the deferred 5GC-MT-LR procedure for periodic or triggered location events in clause 6.3.1 are performed with the following differences.

• At step 16 in clause 6.3.1, the LMF indicates to the UE that DL positioning, RAT Independent positioning or no positioning will be used for subsequent location reporting events when the UE is in RRC INACTIVE state. If DL positioning or RAT independent positioning will be used, the LMF includes an LPP positioning message in the LCS Periodic-Triggered Invoke Request sent to the UE at step 16, where the LPP positioning message requests DL location measurements, RAT independent location measurements or a location estimate based on these location measurements. If no location of the UE is needed for event reporting or if a location based on a Cell ID will suffice for the location QoS, the LMF does not include an LPP positioning message in the LCS Periodic-Triggered Invoke Request sent to the UE at step 16.

The UE enters RRC INACTIVE state some time before an event is detected at step 22 or step 31 in clause 6.3.1. If the UE is not in RRC INACTIVE state when an event is detected at step 22 or step 31 in clause 6.3.1, then the UE follows the procedure described for steps 22-31 in clause 6.3.1 to report the event to the LMF and to the LCS Client or AF.

The UE monitors for and detects a trigger event as described for step 22 in clause 6.3.1.

If DL positioning or RAT independent positioning was indicated at step 1, the UE obtains the location measurements or location estimate requested in the LPP message received in step 1. If DL positioning or RAT independent positioning was not indicated at step 1, this step is skipped.

The UE sends an RRC Resume Request with small data transmission (SDT) to a receiving gNB node in the NG-RAN. The RRC Resume Request includes an RRC UL Information Transfer message containing an UL NAS TRANSPORT message that includes a supplementary services event report message. If DL positioning or RAT independent positioning was indicated at step 1, the UE includes an LPP positioning message in the supplementary services event report message that includes the location measurements or location estimate obtained at step 4. If DL positioning or RAT independent positioning was not indicated at step 1, the UE does not include an LPP positioning message in the supplementary services event report message. The event report message also includes other information described in step 25 in clause 6.3.1 (e.g. the type of event being reported). The UL NAS TRANSPORT message also include the deferred routing identifier received in step 16 in clause 6.3.1.

The receiving gNB node forwards the UL NAS TRANSPORT message to the serving AMF in an N2 Uplink NAS Transport message.

The AMF checks the integrity of the NAS message and deciphers its contents. The AMF then invokes an Namf_Communication_N1MessageNotify service operation to forward the event report to the serving LMF as described for step 25 in clause 6.3.1.

The LMF invokes an Namf_Communication_N1N2MessageTransfer operation to return an acknowledgment for the event report as described for step 26 in clause 6.3.1.

The AMF forwards the acknowledgment to the receiving gNB node in a DL NAS TRANSPORT message which is encapsulated in an N2 Downlink NAS Transport message.

The receiving gNB node sends a Subsequent DL SDT message to the UE and includes the NAS message received in step 10.

The receiving gNB node sends an RRC Release message to the UE to keep the UE in RRC INACTIVE state.

Following step 11, the UE remains in RRC INACTIVE state.

If a location estimate is needed for event reporting, the LMF determines the UE location using the location measurements or location estimate received at step 7 or a Cell ID provided by the AMF at step 7.

Steps 28-31 for clause 6.3.1 are performed to send the event report to the LCS client or AF.