The step is same as step 3 in clause 6.1.1
or clause 6.3.1
with the difference that when the UE is served by more than one AMF the UDM provides to the HGMLC for each access type,
serving AMF identity with the corresponding PLMN Id,
possibly a VGMLC address.
When the HGMLC identifies that the UE is served by different PLMNs according to the returned information from the UDM in step 3 it may retrieve the CM state(s) per Access Type from the candidate AMFs by using Namf_EventExposure
service, or from the UDM using Nudm_EventExposure
service. For each access type the HGMLC selects one access type and its associated AMF based on the UDM returned information in step 3, QoS requirement, CM state(s) of the UE, PLMN identity and/or the locally configured operator policy.
The locally configured operator policy in the HGMLC can include access type and CM state and PLMN priority for positioning. For example, the local policy can be 3GPP access first and/or connected state first and/or V-PLMN and/or H-PLMN first.
The HGMLC forwards the location request to the VGMLC-1 and may include the V-AMF-1 identity received in step 3 and the target UE identity (e.g. SUPI).
The VGMLC-1 invokes the Namf_Location_ProvideLocation_Request service operation to forward the location request to the V-AMF-1. Then the V-LMF-1 receives the location request from the V-AMF-1.
This step is same as step 2-3 of the Common Positioning Procedures in clause 6.9.1
The VGMLC-1 receive the location service response from the V-LMF-1 and for a request for an immediate location, returns positioning results to the HGMLC. For an immediate location, the location service response contains positioning information, the information about the positioning method used and the indication of whether the obtained location estimate satisfies the requested LCS QoS (e.g. accuracy) or not (described in TS 23.271, clause 9.1.1
). For a request for a deferred location, the location service response indicates whether the location request was accepted.
For a request for an immediate location, if the HGMLC identifies that the location service response from the chosen PLMN meets required LCS QoS, it returns the results to the LCS Client directly. Otherwise, the HGMLC may forward the location request to another AMF (in another PLMN) so as to obtain the positioning result which can meet required LCS QoS shown as step 11. For a request for a deferred location, if the HGMLC identifies that location service was accepted (by the chosen PLMN), it returns this indication to the LCS Client directly. Otherwise, the HGMLC may forward the location request to another AMF (in another PLMN).
This step obtains the immediate positioning information or requests a deferred location from another PLMN, the details are the same as steps 5-9.
The HGMLC returns a location service response to the LCS client. For a request for immediate location, if the positioning result from the other PLMN meets the QoS requirement, the HGMLC returns it to the LCS client. Otherwise, the HGMLC returns final location service response without including any positioning result. For a request for deferred location, if the result from the other PLMN indicates acceptance of the location request, the HGMLC returns this to the LCS client. Otherwise, the HGMLC returns a final location service response indicating failure of the deferred location request.