14 5G Location and Positioning Services

21.9163GPPRelease 16Release descriptionTS

14.1 5G positioning services (5G_HYPOS)

800049

Stage 1 of 5G_HYPOS – 5G positioning services

5G_HYPOS

S1

SP-180329

Ries, Lionel, ESA

760006

Study on positioning use cases

FS_5G_HYPOS

S1

SP-170589

Ries, Lionel, ESA

Summary based on the input provided by ESA in SP-200943.

Positioning features and high-accuracy are becoming more and more important for many verticals involved with 5G.

This work item specifies functional requirements as well as KPI to support enhanced positioning services in the 5G systems. It addresses a wide variety of services and use cases, including (but not limited to) regulatory requirements in support of emergency calls and first responder operations, new services in multiple verticals covering for instance industry, logistics, eHealth and aerial.

Emphasis has been put, among other, on improving accuracy, seamless positioning in the entire 5G coverage, flexibility, features to further enable and combine multiple positioning technologies RAT-dependent, RAT-independent such as GNSS and TBS). The work also covers energy efficiency of the positioning function, being key for many use cases such as, for instance, asset tracking.

The work item 5G_HYPOS provides the stage 1 specifications to enable enhanced and more accurate positioning in 5G systems. The positioning services and specifications aim multiple service levels involving different types of UE (e.g. UE for Location Based Services, asset tracking devices, machine-type UE, transportation, etc.), and which can refer to RAT-dependent positioning technologies, RAT-independent positioning technologies (e.g. GNSS, TBS), and/or a combination of several of those.

Functional requirements for positioning services are reported in chapter 6.27 of TS 22.261 [2]. They cover aspects such as configuration of the positioning service capabilities and features, for instance to allow the operators to manage the combination and hybridization of multiple positioning technologies or to report positioning related information to authorized third parties.

KPI for positioning services are reported in chapter 7.3 of TS 22.261 [2]. Several KPIs, such as accuracy, availability, coverage (indoor, outdoor, 5G positioning service area or 5G enhanced positioning service area, etc.) are sorted in 7 Positioning Service Levels, with accuracy ranging from 10 meters for Service Level 1 down to 0.2 meters for Service Level 7. These Service Levels have been coordinated with the needs of industry automation use cases, as specified in TS 22.104 (Service requirements for cyber-physical control applications in vertical domains, [3]), to facilitate the work in subsequent working groups.

Finally, as the work also identified the importance of trusted positioning information to support regulatory and commercial applications, some requirements relating to the integrity and protection of the positioning information and measurements have been introduced in chapter 8.7 of TS 22.261 [2].

The requirements have translated into work in subsequent working groups (SA2, SA3, RAN) and for RAN, in new specifications in: TS 38.215 (NR Physical Layer measurements, [4]), TS 38.305 (Stage 2 functional specification of UE positioning in NG-RAN, [5]), TS 37.355 (LTE Positioning Protocol, [6]), TS 38.455 (NR Positioning Protocol A, [7]) and TS 38.331 (UE radio transmission and reception, [8]) which defines evolution of RAT-dependent technologies for NR, as well as it introduces new features and capabilities in LPP to enable cm-level accuracy positioning with High-Accuracy GNSS (HAGNSS). These specifications address UE-based, UE-assisted methods, and broadcast of information / corrections using RRC System Information messages.

The performance targets for RAT-dependent techniques in Release 16 NR Positioning are matching the TS 22.261 Service Level 1 (<10m) positioning requirements in the case of outdoor users and the SL2 (<3m) requirements in the case of indoor users. High-accuracy GNSS, based on State Space Representation corrections (SSR), has been added to the list of positioning techniques supported by LPP and it is able to meet service levels captured in TS 22.261 for majority of outdoor users with its expected performance (<1m) .

References

List of related CRs: select "TSG Status = Approved" in:
https://portal.3gpp.org/ChangeRequests.aspx?q=1&workitem=800049,760006

[1] Tdoc SP-180329, “New WID on 5G positioning services (5G_HYPOS)”

[2] TS 22.261 Service requirements for the 5G system; Stage 1

[3] TS 22.104 Service requirements for cyber-physical control applications in vertical domains; Stage 1

[4] TS 38.215 “NR Physical Layer measurements”

[5] TS 38.305 “Stage 2 functional specification of UE positioning in NG-RAN”

[6] TS 37.355 “LTE Positioning Protocol (LPP)”

[7] TS 38.455 “NR Positioning Protocol A (NRPPa)”

[8] TS 38.331 “UE radio transmission and reception”

14.2 Enhancement to the 5GC LoCation Services

830102

Enhancement to the 5GC LoCation Services

5G_eLCS

S2

SP-181119

Ming Ai, CATT

780028

Study on Enhancement to the 5GC Location Services

FS_eLCS

S2

SP-180734

Ming Ai, CATT

810035

Study on Security of the enhancement to the 5GC location services

FS_eLCS_Sec

S3

SP-180694

Wei Zhou, CATT

820016

Stage 2 of 5G_eLCS

5G_eLCS

S2

SP-181119

Ming Ai, CATT

830003

CT aspects of 5G_eLCS

5G_eLCS

ct

CP-190014

Tingfang Tang, CATT

830044

CT1 aspects of 5G_eLCS

5G_eLCS

C1

CP-191064

Tingfang Tang, CATT

830045

CT3 aspects of 5G_eLCS

5G_eLCS

C3

CP-191064

Tingfang Tang, CATT

830046

CT4 aspects of 5G_eLCS

5G_eLCS

C4

CP-191064

Tingfang Tang, CATT

Summary based on the input provided by CATT in SP-191223.

This work item defines the stage 2 of the service-based architecture used for location services in the 5G system, and corresponding Network Functions (NFs), NF services and procedures, to meet the service requirements defined in TS 22.261 [1] and TS 22.071 [2].

The Location Services, specified in TS 23.273 [3], include aspects of both regulatory and commercial nature.

The architecture and signalling procedures in NG-RAN are defined in TS 38.305 [4].

Following aspects have been specified for 5G Location Services:

– Service based 5G location architecture, including roaming and non-roaming, Function description of per Network Functions, etc.

– General Concepts, e.g. Type of Location Requests, LCS Quality of services;

– High Level Features, e.g. LMF selection, UE LCS privacy handling;

– Location Service Procedures, which includes

– 5GC-MT-LR Procedure

– 5GC-MO-LR Procedure

– Deferred 5GC-MT-LR Procedure for Periodic, Triggered and UE Available Location Events

– LMF Change Procedure

– Unified Location Service Exposure Procedure

– Low Power Periodic and Triggered 5GC-MT-LR Procedure

– Bulk Operation of LCS Service Request Targeting to Multiple UEs

– Procedures to Support Non-3GPP Access

– Procedures dedicated to Support Regulatory services

– UE Assisted and UE Based Positioning Procedure

– Network Assisted Positioning Procedure

– Obtaining Non-UE Associated Network Assistance Data

– UE Location Privacy Setting Procedure

– Procedures with interaction between 5GC and EPC

– Support of Concurrent Location Request;

– Network Function Services, e.g. LMF services, GMLC services.

References

List of related CRs: select "TSG Status = Approved" in:
https://portal.3gpp.org/ChangeRequests.aspx?q=1&workitem=830102,780028,810035,820016,830003,830044,830045,830046

[1] TS 22.261: "5G system; Services, operations and procedures of charging using Service Based Interface (SBI)"

[2] TS 22.071: "Service requirements for next generation new services and markets; Stage 1"

[3] TS 23.273: "5G System (5GS) Location Services (LCS); Stage 2"

[4] TS 38.305: "Stage 2 functional specification of User Equipment (UE) positioning in NG-RAN".

14.3 NR positioning support

830077

NR positioning support

NR_pos

R1

RP-191156

Intel

800092

Study on NR positioning support

FS_NR_pos

R1

RP-181399

Intel

830073

Study on local NR positioning in NG-RAN

FS_NR_local_pos

R3

RP-190754

CMCC

830177

Core part: NR positioning support

NR_pos-Core

R1

RP-190752

Intel

830277

Perf. part: NR positioning support

NR_pos-Perf

R4

RP-190752

Intel

Summary based on the input provided by Intel Corporation in RP-201987.

In the presented work item [1] 3GPP defined framework for NR based positioning of UEs, including definition of new reference signals, physical layer measurements, procedures and higher layer protocols for support of NR RAT-dependent and RAT-independent positioning technologies. This completed normative work [2] is a continuation of the 3GPP Rel.16 study item on NR Positioning Support [3]. The main motivation behind this work is to support accurate UE positioning in NR technology by utilizing RAT-dependent and RAT-independent solutions.

RAT-dependent positioning techniques

In the NR positioning WI 3GPP specified support for the following RAT-dependent positioning techniques (defined in TS 37.355):

• DL TDOA – Downlink Time Difference of Arrival

• DL AoD – Downlink Angle of Departure

• UL TDOA – Uplink Time Difference of Arrival

• UL AoA – Uplink Angle of Arrival (Azimuth and Zenith)

• Multi-RTT – Multi Round Trip Time

• NR E-CID – NR Enhanced Cell ID

These positioning methods may be supported in UE-based, UE-assisted/LMF-based, and NG-RAN node assisted versions.

Table 1: Supported versions of UE positioning methods (defined in TS38.305)

Method

UE-based

UE-assisted, LMF-based

NG-RAN node assisted

DL-TDOA

Yes

Yes

No

DL-AoD

Yes

Yes

No

Multi-RTT

No

Yes

Yes

NR E-CID

No

Yes

Yes

UL-TDOA

No

No

Yes

UL-AoA

No

No

Yes

Physical layer signals and measurements: In order to support RAT-dependent positioning solutions, the following new reference signals and new physical layer measurements were specified:

• Reference signals (defined in TS 38.211)

o DL Positioning Reference Signals (DL PRS)

o UL Sounding Reference Signals (SRS) for positioning

• Physical layer measurements (defined in TS 38.215)

o UE measurements

– DL PRS-RSRP (downlink positioning reference signals – reference signal receiver power): Applied for DL AoD, DL TDOA, Multi-RTT

– DL RSTD (downlink reference signal time difference): Applied for DL TDOA

– UE Rx – Tx time difference: Applied for Multi-RTT

o NG-RAN (gNB) measurements

– UL RTOA (uplink relative time of arrival): Applied for UL TDOA

– UL SRS reference signal received power (UL SRS-RSRP): Applied for UL TDOA, UL AoA, Multi-RTT

– gNB Rx – Tx time difference: Applied for Multi-RTT:

– UL AoA (uplink angle of arrival): Applied for UL AoA and E-CID

In addition, the existing RRM measurements were reused for NR E-CID support: CSI-RSRP, CSI-RSRQ, SS-RSRP, SS-RSRQ.

Downlink positioning reference signal (DL PRS): they are allocated and transmitted periodically with configurable periodicity and time offset with respect to SFN0. The DL PRS configuration is done per DL positioning frequency layer that defines multiple DL PRS resource sets associated with different transmission/reception points (TRPs) and characterized by the same DL PRS subcarrier spacing, transmission bandwidth, cyclic prefix length, DL PRS Point A and offset with respect to DL PRS Point A. DL PRS resource set may contain multiple DL PRS resources, where each DL PRS resource is associated with certain spatial transmission direction of DL PRS from a given TRP (beam) and characterized by configurable number of symbols, resource element pattern, initial comb-offset, offset in slots, symbols and DL PRS sequence ID.

DL PRS is single port signal that can be configured as quasi-collocated with SSB index or other DL PRS resources. The configuration of DL PRS is provided as a part of UE assistance information. DL PRS transmissions can be muted according to configured bitmaps for each DL PRS resource set that control the DL PRS resource set transmission period or DL PRS resource repetition transmission within a DL PRS transmission period.

Uplink sounding reference signals for positioning: they are defined based on NR UL SRS with modified staggered RE pattern and disabled frequency hopping. The UL SRS for positioning are defined through configuration of UL SRS resource sets for positioning, where each set may contain multiple UL SRS resources for positioning. UL SRS resource for positioning is characterized by number of symbols, transmission bandwidth, RE pattern, time offset and may be associated with UE TX beam. UL SRS resources for positioning can be spatially related with SSB indexes or DL PRS resource index as well as reference signal for UL open loop power control towards serving and neighbor cells (defined for UL SRS for positioning).

LMF may recommend the spatial relation and pathloss reference to the gNB for SRS configuration. LMF may also request activation and deactivation of non-periodic SRS transmission to the gNB.

Broadcast of Assistance Data: this can be included in positioning System Information Blocks (posSIBs) which are carried in RRC System Information (SI) messages. The UE may request posSI by means of on-demand SI request in RRC_IDLE/RRC_INACTIVE and also request posSIBs by means of on-demand SI request in RRC_ CONNECTED.

For each assistance data element, a separate posSIB-type is defined. Each posSIB may be ciphered by the LMF using the 128-bit Advanced Encryption Standard (AES) algorithm (with counter mode), either with the same or different ciphering key.

RAT independent positioning techniques: PPP and RTK, are already supported in Rel-15 LPP. In Rel-16, LPP is extended to support GNSS SSR (PPP-RTK support) based on the “Compact SSR” definitions specified for QZSS for both LTE and NR. Following additional information are added to be transferred from the LMF to UE:

– SSR Phase Bias

– SSR STEC Corrections

– SSR Gridded Correction

– SSR URA

– SSR Correction Points

Positioning network architecture: In the positioning architecture specified in TS 38.305 and TS 38.401, the LMF is connected to the NG-RAN node through the AMF. The NG-RAN node may control several TRPs. Both split (i.e. CU/DU) and non-split NG-RAN architectures are supported. The NRPPa and the F1AP protocols have been extended to support the positioning methods listed above.

UE DL PRS processing requirements: For defined physical layer measurements DL-RSTD, DL PRS-RSRP and UE Rx-Tx time difference in Rel16, the requirements on the measurement time were defined. These requirements are applicable for the case when measurement gap is configured to UE. The UE processing capabilities specified in TS 37.355 are taken into account to derive total DL PRS measurement delay.

Measurement gaps: On top of legacy measurement gap patterns, the new measurement gap patterns with > 6ms measurement gap length (MGL) were introduced in Rel16 for NR positioning.

MG length (ms)

MG period (ms)

20

160

10

80

These two gap patterns can be requested by the UE and configured by the network only when the UE is configured via LPP with NR positioning measurements and can only be used during the corresponding positioning measurement period. The supported measurement gaps are applicable for DL PRS and NR/LTE RRM measurements i.e. new gaps are not shared between PRS and 2G/3G RRM measurements.

References

List of related CRs: select "TSG Status = Approved" in:
https://portal.3gpp.org/ChangeRequests.aspx?q=1&workitem=830077,800092,830073,830177,830277

[1] RP-190752, “New WID: NR Positioning Support”, Intel Corporation, Ericsson

[2] RP-201835, “Status Report to TSG on NR Positioning Support”, Intel Corporation

[3] TR 38. 855 “Study on NR positioning support” v16.0.0