8.9 NR Enhanced cell ID positioning methods

38.3053GPPNG Radio Access Network (NG-RAN)Release 17Stage 2 functional specification of User Equipment (UE) positioning in NG-RANTS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

8.9.1 General

NR Enhanced Cell ID (NR E-CID) positioning refers to techniques which use UE and/or NR radio resource related measurements to improve the UE location estimate. In the case of uplink NR E-CID inter-RAT E-UTRA measurements reported by UE may also be used.

NOTE 1: For NR E-CID positioning methods the UE reports only the measurements that it has available rather than being required to take additional measurement actions. Therefore, the measurement gap request procedure described in clause 7.4.1.1 is not applicable for NR E-CID positioning methods.

NR E-CID measurements may include:

UE measurements (TS 38.215 [37]):

– SS Reference signal received power (SS-RSRP);

– SS Reference Signal Received Quality (SS-RSRQ);

– CSI Reference signal received power (CSI-RSRP);

– CSI Reference Signal Received Quality (CSI-RSRQ).

The UE measurements above may be aggregated at cell level or measured per SSB or CSI-RS resource.

NR E-CID UE measurements for other RAT may include:

– E-UTRA Reference signal received power (RSRP);

– E-UTRA Reference Signal Received Quality (RSRQ);

NOTE 2: The above E-UTRA measurements by UE are only used for Uplink NR E-CID positioning.

gNB measurements (TS 38.215 [37]):

– UL Angle of Arrival (azimuth and elevation);

– Timing advance (T_ADV).

Various techniques exist to use these measurements to estimate the location of the UE. The specific techniques are beyond the scope of this specification.

8.9.2 Information to be transferred between NG-RAN/5GC Elements

This clause defines the information that may be transferred between LMF and UE and from gNB to LMF.

8.9.2.1 Information that may be transferred from the LMF to UE

UE-assisted NR Enhanced Cell-ID location does not require any assistance data to be transferred from the LMF to the UE.

UE-Based NR Enhanced Cell-ID location is not supported in this version of the specification.

8.9.2.2 Information that may be transferred from the UE to LMF

The information that may be signalled from UE to the LMF is listed in table 8.9.2.2-1.

Table 8.9.2.2-1: Information that may be transferred from UE to the LMF

Information	UE‑assisted
SS Reference signal received power (SS-RSRP)	Yes
SS Reference Signal Received Quality (SS-RSRQ)	Yes
CSI Reference signal received power (CSI-RSRP)	Yes
CSI Reference Signal Received Quality (CSI-RSRQ)	Yes
NR Cell Global Identifier, Physical Cell ID	Yes

8.9.2.3 Information that may be transferred from the gNB to LMF

The information that may be transferred from gNB to the LMF is listed in table 8.9.2.3-1.

Table 8.9.2.3-1: Information that may be transferred from gNB to the LMF

Information

UL Angle of Arrival (azimuth and elevation)

Cell Portion ID

NR Measurement Results List:

– SS Reference signal received power (SS-RSRP)

– SS Reference Signal Received Quality (SS-RSRQ)

– CSI Reference signal received power (CSI-RSRP)

– CSI Reference Signal Received Quality (CSI-RSRQ)

– NR Cell Global Identifier /Physical Cell ID

– Timing Advance (T_ADV)

E-UTRA Measurement Results List:

– E-UTRA Physical Cell ID

– E-UTRA Reference Signal Received Power (RSRP)

– E-UTRA Reference Signal Received Quality (RSRQ)

Both cell-level and beam-level measurements for SS-RSRP, SS-RSRQ, CSI-RSRP and CSI-RSRQ are supported.

8.9.3 Downlink NR E-CID Positioning Procedures

The procedures described in this clause support NR E-CID related measurements obtained by the UE and provided to the LMF using LPP. The term "downlink" is intended to indicate that from the LMF perspective the involved measurements are provided by the UE; this set of procedures might also be considered as "UE-assisted, LMF-based NR E-CID".

8.9.3.1 Capability Transfer Procedure

The Capability Transfer procedure for NR E-CID positioning is described in clause 7.1.2.1.

8.9.3.2 Assistance Data Transfer Procedure

Assistance data transfer is not required for NR E-CID positioning.

8.9.3.3 Location Information Transfer Procedure

The purpose of this procedure is to enable the LMF to request position measurements from the UE, or to enable the UE to provide location measurements to the LMF for position calculation.

8.9.3.3.1 LMF-initiated Location Information Transfer from UE

Figure 8.9.3.3-1 shows the Location Information Transfer operations for the NR E-CID method from UE when the procedure is initiated by the LMF.

Figure 8.9.3.3.1-1: LMF-initiated Location Information Transfer Procedure.

(1) The LMF sends a LPP Request Location Information message to the UE for invocation of NR E-CID positioning. This request includes the NR E-CID measurements requested by the LMF and supported by the UE as listed in Table 8.9.2.2-1 together with a required response time.

(2) The UE sends an LPP Provide Location Information message to the LMF and reports the requested measurements that are available in the UE before the Response Time provided in step (1) elapsed. If the requested measurements are not available, or if the Response Time provided in step 1 elapsed before any of the requested measurements have been obtained, the UE returns any information that can be provided in an LPP message of type Provide Location Information which includes a cause indication for the not provided location information.

8.9.3.3.2 UE-initiated Location Information Delivery procedure

Figure 8.9.3.3.2-1 shows the Location Information Delivery procedure operations for the NR E-CID method when the procedure is initiated by the UE.

Figure 8.9.3.3.2-1: UE-initiated Location Information Delivery Procedure.

(1) The UE sends an LPP Provide Location Information message to the LMF. The Provide Location Information message may include any UE measurements already available at the UE.

8.9.4 Uplink NR E-CID Positioning Procedures

The procedures described in this clause support NR E-CID related measurements obtained by the serving gNB and provided to the LMF using NRPPa. The term "uplink" is intended to indicate that from the LMF perspective the involved measurements are provided by the serving gNB; this set of procedures might also be considered as "NG-RAN node assisted NR E-CID".

8.9.4.1 Capability Transfer Procedure

The Capability Transfer procedure is not applicable to UL NR E-CID positioning.

8.9.4.2 Assistance Data Transfer Procedure

Assistance data transfer is not required for UL NR E-CID positioning.

8.9.4.3 Location Information Transfer Procedure

The purpose of this procedure is to enable the LMF to request position measurements from the gNB.

Figure 8.9.4.3-1 shows the messaging between the LMF and the gNB to perform this procedure.

Figure 8.9.4.3-1: LMF-initiated Location Information Transfer Procedure

(1) The LMF sends an E-CID Measurement Initiation Request message to the serving gNB to request NR E-CID measurement information. The message includes indication of NR E-CID measurements requested and whether the result is expected only once or periodically.

(2) If the report characteristics in step 1 is set to "on demand", the gNB obtains the requested NR E-CID measurements and returns them in an E-CID Measurement Initiation Response message to the LMF. The E-CID Measurement Initiation Response message includes the obtained NR E-CID measurements as defined in the clause 8.9.2.3.

If the report characteristics in step 1 is set to "periodic", the gNB replies with an E-CID Measurement Initiation Response message without including any measurements in the message. The gNB then periodically initiates the E-CID Measurement Report procedure in step 3 for the NR E-CID measurements, with the requested reporting periodicity.

If the gNB is not able to accept the E-CID Measurement Initiation Request message in step 1, the gNB returns a failure message indicating the cause of the failure.

(3) The gNB periodically provides the NR E-CID measurements as defined in the clause 8.9.2.3 to the LMF if that was requested at step 1.

(4) If the previously requested NR E-CID measurements can no longer be reported, the gNB notifies the LMF by sending an E-CID Measurement Failure Indication message.

(5) When the LMF wants to terminate an ongoing NR E-CID measurement it sends an E-CID Measurement Termination Command message to the gNB.