A.1 RAN Induced Location Request (RI-LR)

38.8563GPPRelease 16Study on local NR positioning in NR Radio Access Network (RAN)TS

The LMC should be able to support location service requests from functions internal to the NG-RAN node, this type of location request can be called RAN Induced Location Request (RI-LR). The LMC is ideally suited to handle RI-LR since the necessary operations are internal to the RAN and can therefore be handled locally.

Note: whether service request can come from an internal function of the serving NG-RAN node should be check with SA groups.

Figure A.1 illustrates the steps applicable to the UE and NG-RAN node in case of RI-LR involving LMC.

In this scenario, the UE is assumed to be in connected mode prior to step 1. The procedure assumes that the NG-RAN node is authorized to use the LCS service to obtain the target UE location estimation, and that notification and/or verification of location by the UE is not needed, e.g. which may be indicated in UDM privacy subscription for the UE and signaled to the serving gNB by the serving AMF as part of signaling connection establishment.

Figure A.1: RI-LR involving LMC

The steps of Figure A.1 are as follows: The steps of Figure 5.2.1.1-1 are as follows:

1. Some function in the NG-RAN node (e.g. RRM, MDT) requests some location service (e.g. positioning) for a target UE to the LMC using signaling internal to the NG-RAN node.

2. The NG-RAN node (LMC) sends an LCS Indication message to the AMF, indicating that UE positioning is being performed locally (LCS session start). The LCS Indication message includes information about the "local" LCS Request that may be useful for the AMF (location management information), e.g. the same or subset of information contained in a "normal" location service request (e.g. MT-LR) such as Location Quality of Service information.

3. The AMF stores the relevant location management information in the UE location context, to be used for coordination of concurrent LCS requests, e.g. if the AMF receives an MT-LR while there is an active location session at the LMC for the same UE.

4a. The LMC may instigate location procedures internal to the NG-RAN node – e.g. to obtain positioning measurements or assistance data. The LMC may also instigate location procedures with neighbor NG-RAN nodes – e.g. to obtain assistance data such as PRS configuration of TPs served by the neighbor NG-RAN node(s).

4b. The LMC may instigate location procedures with the UE – e.g. to obtain a location estimate or positioning measurements or to transfer location assistance data to the UE.

5. The LMC responds to the requesting function in the NG-RAN node and includes any needed results – e.g. success or failure indication and, if requested and obtained, a location estimate for the UE.

6. If the response in step 5 ends the local LCS session, the NG-RAN node (LMC) sends an LCS Indication message to the AMF indicating that positioning is no longer being performed locally for the target UE (LCS session stop).

Note: Steps 2 and 6 assume that AMF awareness of RI-LR is needed to enable coordination and coexistence with LMF as described in subclause 5.3. SA2 involvement may be needed.

Annex B (informative):
Change history

Change history

Date

Meeting

Tdoc

CR

Rev

Cat

Subject/Comment

New version

2019-8-26

RAN3 #105

R3-184476

First Skeleton provided

0.0.0

2019-8-31

RAN3 #105

Include the agreed TP in R3-194760

0.1.0

2019-10-24

RAN3 #105bis

Include the agreed TP in R3-196223, R3-196224, R3-196225, R3-196226

0.2.0

2019-11-25

RAN3 #106

Include the agreed TP in R3-197698, R3-197695, R3-197790, R3-197697, editorial changes and remove FFSs

0.3.0

2019-12

RAN #86

One-step approval

1.0.0

2019-12

RAN#86

TS approved by TSG RAN plenary

16.0.0