Content for  TS 23.273  Word version:  18.5.0

The AMF invokes the Nlmf_Location_DetermineLocation service operation towards the LMF to request the current location of the UE, which includes the QoS requirement and UE connectivity state per access type.

The LMF determines the positioning access type and the positioning method based on the UE/network positioning capability, the QoS requirement and UE connectivity state per access type received from the AMF and the locally configured operator policy. The LMF may also determine the access type for transmission of an LPP message to the UE (e.g. in order to ensure the UE will be in a connected state for the selected positioning access type). When the LPP protocol in TS 37.355 is determined to be used to obtain location information from the UE and the UE has both 3GPP and non-3GPP access, the AMF shall decide which access type should be used to transmit the location information if the LMF did not select an access type. For example, if the UE is in CM-IDLE state in 3GPP access and in CM-CONNECTED state in Non-3GPP access, AMF may prefer to select the N3IWF/TNGF/W-AGF to relay positioning signalling to UE, rather than performing paging procedures via the 3GPP access. When the NRPPa protocol in TS 38.455 is determined to be used to obtain location information from the NG-RAN or N3IWF/TNGF/W-AGF:

• In the case that 3GPP Access is determined to be used to transmit the location information, the Network Assisted Positioning procedure in step 3b and/or the obtaining Non-UE Associated Network Assistance Data procedure in step 3c shall be performed.
• In the case that non-3GPP Access is determined to be used to obtain the location information, the Network Assisted Positioning procedure in step 3e shall be performed.
• When the LPP protocol in TS 37.355 is determined to be used to obtain location information from the UE:
• In the case that 3GPP Access is determined to be used to relay the location information, the UE Assisted and UE Based Positioning procedure in step 3a shall be performed.
• In the case that non-3GPP Access is determined to be used to relay the location information, the UE Assisted and UE Based Positioning procedure in step 3d shall be performed.

This step is same as the UE Assisted and UE Based Positioning procedure in clause 6.11.1.

This step is same as the Network Assisted Positioning procedure in clause 6.11.2 with the difference that step 1 of clause 6.11.2 includes the selected Access Type (i.e. 3GPP access). The AMF forwards the Network Positioning message to the NG-RAN in step 3 of clause 6.11.2 based on the received Access Type.

This step is same as the Obtaining Non-UE Associated Network Assistance Data procedure in clause 6.11.3.

This step is same as the UE Assisted and UE Based Positioning procedure in clause 6.11.1 with the following difference:

• The NG-RAN in clause 6.11.1 is replaced by the N3IWF/TNGF/W-AGF in Figure 6.9.1-1;
• Steps 2 and 5 in clause 6.11.1 are omitted;
• The location information returned by the UE can include information specified in clause 5.3.1.

This step is same as the Network Assisted Positioning procedure in clause 6.11.2 with the following difference:

• The NG-RAN in clause 6.11.2 is replaced by the N3IWF/TNGF/W-AGF in Figure 6.9.1-1;
• Steps 2 and 4 in clause 6.11.2 are omitted;
• The Access Type, i.e. non-3GPP access type, which is selected to provide the location information is included in step 1 of clause 6.11.2. The AMF forwards the Network Positioning message to the N3IWF/TNGF/W-AGF based on the received Access Type in step 1 of clause 6.11.2.
• The location information returned in step 5 of clause 6.11.2 is specified in clause 5.3.1.

The UE is replaced by 5G-RG in the case of wireline access type.

The step is same as step 1 in clause 6.1.1 or clause 6.3.1.

The step is same as step 2 in clause 6.1.1 or clause 6.3.1.

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. The HGMLC selects one access type and its associated AMF based on the UDM returned information in step 3, QoS requirement, CM state(s) per Access type of the UE, PLMN identity and/or the locally configured operator policy.

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 clause 9.1.1 of TS 23.271). 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.