EP4595607A1

EP4595607A1 - Providing and supporting location services via direct device-to-device connections

Info

Publication number: EP4595607A1
Application number: EP23718776.0A
Authority: EP
Inventors: Hyung-Nam Choi; Robin Thomas; Dimitrios Karampatsis
Original assignee: Lenovo Singapore Pte Ltd
Current assignee: Lenovo Singapore Pte Ltd
Priority date: 2023-03-09
Filing date: 2023-04-18
Publication date: 2025-08-06
Also published as: CN120345314A; GB202506603D0; GB2639792A; WO2024083356A1

Abstract

The application relates to aspects of supporting UE location services via direct device-to-device connections between UEs (e.g. Sidelink connections). Accordingly, a mobile telecommunications network apparatus for implementing a determination of a target communication device location is provided. The apparatus includes a first interface configured to provide communication with a mobile telecommunications network via a radio unit, and a second interface configured to provide direct device-to-device communication within a proximity range via the radio unit. The apparatus is configured to establish a direct device-to-device connection to a communication device within the proximity range via the second interface. Subsequently, the apparatus transmits a location request message to the communication device via the established connection. The location request message comprises a request to determine the location of the target communication device and accuracy parameters indicating a target accuracy for the location determination. In response to the location request message, the apparatus receives a location response message from the communication device via the established connection, the location response message comprising data indicating the location of the target communication device determined in accordance with the accuracy parameters.

Description

Providing And Supporting Location Services Via Direct Device-To-Device Connections

BACKGROUND

Modern Public Land Mobile Networks (PLMN) support positioning services to connected user equipment (UE). The currently supported positioning technologies are either directly provided by a location function of the PLMN (RAT-dependent) or are independent from Radio Access Technology (RAT). Positioning techniques that are provided by the PLMN rely on a connection to a PLMN via a Radio Access Network (RAN) node such as an eNB, an NG-eNB, or a gNB. RAT- independent technologies can be performed by a single UE without coordination with the PLMN (e.g. positioning via a Global Navigation Satellite System, GNSS). RAT-dependent techniques may fail in situations where a UE is out-of-coverage of a RAN node. Even if a target UE is within coverage of a RAN node, the network-based location services may introduce an unacceptable latency. Additionally, RAT-independent technologies may not be available (e.g. in indoor scenarios) or may fail to meet the expected accuracy or latency requirements.

The 3GPP Release 16 introduced an extension of 5G new radio networks that allows direct device-to-device communication between UEs. This device-to-device communication standard is called Sidelink (SL) and uses the New Radio air interface of the 5G system. Sidelink provides a direct connection between UEs in proximity to each other. Sidelink may provide a basis for providing accurate and low latency positioning services that are available even outside the PLMN coverage. However, the currently available technologies do not provide robust and efficient positioning procedures based on direct device-to-device communication such as Sidelink.

SUMMARY

An aspect of the invention is to provide mobile telecommunications network apparatuses for implementing improved location services for determining a user equipment (UE) location via direct device-to-device connections.

In order to overcome the above deficiencies a mobile telecommunications network apparatus (i.e. a UE) is presented. The apparatus includes a first interface configured to provide communication with a mobile telecommunications network (e.g. a cellular network such as an LTE network or a 5G new radio network) via a radio unit. The apparatus further includes a second interface configured to provide direct device-to-device (i.e. UE-to-UE) communication within a proximity range via the radio unit. The apparatus comprises one or more processors configured to execute computer-readable instructions for implementing a determination of a target communication device location. The instructions cause the one or more processors to establish a direct device-to-device connection to a communication device (i.e. a UE) within the proximity range via the second interface, to transmit a location request message to the communication device via the established connection, and to receive a location response message from the communication device via the established connection. The location request message comprises a request to determine the location of the target communication device and one or more accuracy parameters indicating a target accuracy for the location determination. The one or more accuracy parameters comprise at least one of a relative accuracy parameter, an absolute accuracy parameter for a distance determination, and an absolute accuracy parameter for a direction determination. The location response message comprises data indicating a location of the target communication device determined in accordance with the one or more accuracy parameters.

In a further aspect a mobile communication network apparatus (i.e. a UE) is provided which includes a first interface configured to provide communication with a mobile telecommunications network (e.g. a cellular network such as an LTE network or a 5G new radio network) via a radio unit. The apparatus further includes a second interface configured to provide direct device-to- device communication within a proximity range via the radio unit. The apparatus comprises one or more processors configured to execute computer-readable instructions for implementing a determination of a target communication device location. The instructions cause the one or more processors to establish a direct device-to-device connection to a communication device (i.e. a UE) within the proximity range via the second interface, to receive a location request message from the communication device via the established connection, to determine the location of the target communication device, and to transmit a location response message to the communication device via the established connection. The location request message comprises a request to determine the location of the target communication device and one or more accuracy parameters indicating a target accuracy for the location determination. The one or more accuracy parameters comprise at least one of a relative accuracy parameter, an absolute accuracy parameter for a distance determination, and an absolute accuracy parameter for a direction determination. The determination of the location of the target location device is performed in accordance with the one or more accuracy parameters. The location response message comprises data indicating the determined location of the target communication device.

In another aspect a mobile telecommunications network apparatus (i.e. a UE) is provided which includes a first interface configured to provide communication with a mobile telecommunications network (e.g. a cellular network such as an LTE network or a 5G new radio network) via a radio unit. The apparatus further includes a second interface configured to provide direct device-to-device communication within a proximity range via the radio unit. The apparatus comprises one or more processors configured to execute computer-readable instructions for implementing discovery of communication devices for device location determination. The instructions cause the one or more processors to establish a direct device-to-device connection to a first communication device (i.e. a UE) within the proximity range via the second interface, to receive a positioning request message from the first communication device via the established connection, the positioning request message including a request to discover a second communication device (i.e. a UE) within the proximity range. Subsequently, the instructions cause the one or more processors to discover the second communication device in accordance with the received positioning request message and to transmit a positioning response message to the first communication device via the established connection indicating that the second communication device has been discovered.

In yet another aspect a mobile telecommunications network apparatus (i.e. a UE) is provided including a first interface configured to provide communication with a mobile telecommunications network (e.g. a cellular network such as an LTE network or a 5G new radio network) via a radio unit. The apparatus further comprises a second interface configured to provide direct device-to-device communication within a proximity range via the radio unit. The apparatus comprises one or more processors configured to execute computer-readable instructions for assisting in determining a location of a target communication device (i.e. a target UE). The instructions cause the one or more processors to establish a direct device-to-device connection to a communication device (i.e. a UE) within the proximity range via the second interface and to transmit an assistance data activation request message to the communication device via the established connection. The assistance data activation request message includes a request to activate the transmission of assistance data by transmitting a positioning reference signal to the target communication device. The assistance data activation request message is configured to cause the communication device to select a configuration type for the positioning reference signal and to transmit the positioning reference signal in accordance with the selected configuration type to the target communication device via a direct device-to-device connection. The configuration type specifies properties of the positioning reference signal, which is configured to enable the target communication device to perform measurements based on the positioning reference signal for determining the location of the target communication device. In a further aspect a mobile telecommunications network apparatus (i.e. a UE) is provided, the apparatus including a first interface configured to provide communication with a mobile telecommunications network (e.g. a cellular network such as an LTE network or a 5G new radio network) via a radio unit. The apparatus further includes a second interface configured to provide direct device-to-device communication within a proximity range via the radio unit. The apparatus comprises one or more processors configured to execute computer-readable instructions for assisting in determining a location of a target communication device (i.e. a target UE). The instructions cause the one or more processes to establish a direct device-to-device connection to a communication device (i.e. a UE) within the proximity range via the second interface and to receive an assistance data activation request message from the communication device via the established connection. The assistance data activation request message includes a request to activate the transmission of assistance data by transmitting a positioning reference signal to a target communication device. The instructions further cause the one or more processors, in response to receiving the assistance data activation request message, to select a configuration type for the positioning reference signal and to transmit the positioning reference signal in accordance with the selected configuration type to the target communication device over a direct device-to-device connection via the second interface. The configuration type specifies properties of the positioning reference signal. The positioning reference signal is configured to enable the target communication device to perform measurements based on the positioning reference signal for determining the location of the target communication device.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments and aspects of the invention will be described in the following description together with the accompanying drawings, wherein

Fig. 1 is a diagram showing a conventional 3GPP telecommunications network architecture for providing network-based location services to user equipment;

Fig. 2 is a diagram showing three exemplary network configurations in which location services may be provided;

Fig. 3 is a diagram illustrating an exemplary configuration of a mobile telecommunications network apparatus; Fig. 4 is an exemplary flow diagram showing a signal flow between a plurality of communication devices for client-initiated location determination of a target user equipment via direct device-to-device connections;

Fig. 5 is an exemplary flow diagram illustrating a signal flow between a plurality of communication devices for target-initiated location determination for a target user equipment via direct device-to-device connections;

Fig. 6 is an exemplary flow diagram showing a signal flow between a plurality of communication devices for an activation of assistance data transmission for locating a target user equipment; and

Fig. 7 is an exemplary flow diagram showing another signal flow between a plurality of communication devices for an activation of assistance data transmission for locating a target user equipment.

DETAILED DESCRIPTION

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings in which like reference numerals refer to like elements unless specified otherwise.

1. Support For Positioning In Mobile Communication Networks

In Release 15 (Rel-15) of the 3GPP standard, the 5G air interface (New Radio, NR) supports only Cell-ID and positioning methods that are independent of the radio access technology (RAT). Positioning of a UE with Cell-ID is based on the known positions of cell towers and the signal strength from the cell towers measured at the UE. The UE is able to identify the cell tower that sent the received signal by a Cell-ID of the cell tower, which is transmitted with the signal. Among the supported RAT-independent technologies is UE positioning via global navigation satellite systems (GNSS, e.g. GPS, Galileo, etc.).

In order to meet the positioning requirements for regulatory (i.e. emergency services) and commercial use cases (e.g. Industrial Internet of Things, I loT), additional positioning methods have been specified in 3GPP Release 16. These additional positioning methods include RAT- dependent methods in both supported frequency ranges FR1 and FR2 and RAT-independent positioning methods such as Precise Point Positioning (PPP) and Real-Time Kinematik (RTK). A list of RAT-dependent positioning methods that are supported in 3GPP Release 16 is provided in Table 1. These methods rely on the coordination of several PLMN network elements to provide positioning services for a target UE. Some of these methods can be performed by the target UE itself but rely on additional assistance from a location management function (LMF) of the network and/or one or more next generation radio access network (NG-RAN) nodes such as a gNB or an NG-eNB. Other supported methods are not performed by the target UE itself but by other network elements such as the LMF or an NG-RAN node.

Table 1

The supported positioning methods include Downlink and Uplink Time Difference of Arrival (DL-TDOA and UL-TDOA). In the Downlink variant, a UE receives a measurement signal (e.g. a Positioning Reference Signal, PRS) from at least three network transmission points (e.g. Transmission and Reception Points, TRPs in a 5G Network or separate base stations) and evaluates the differences in the arrival times of these signals. Together with the known positions of the transmission points, the UE is able to determine its own location. In the Uplink case, the measurement signal is sent by the UE and received by at least three network receivers (e.g. TRPs or base stations). Based on the time difference of the received signals and the positions of the receiver points the location of the UE can be determined.

The supported positioning methods Downlink Angle of Departure (DL-AoD) and Uplink Angle of Arrival (UL-AoA) are also based on a measurement signal (e.g. PRS) exchange between a target UE and a number of network points (i.e. TRPs or base stations). These techniques evaluate the angle of the signal at the UE (Downlink) or at the network point (Uplink) together with the known positions of the network points to determine the location (i.e. position) of the target UE.

In the Multi Round Trip Time (Multi-RTT) positioning method, the target UE position is determined based on measurements performed at both the target UE and network points (e.g. TRPs or base stations). The measurements performed at the UE and TRPs are time difference measurements between the transmission and the reception of the measurement signals, which are used by a network function (e.g. LMF) to determine the Round Trip Times and the resulting location of the target UE.

Finally, New Radio 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. According to TS 38.215 the UE measurements may include Synchronization Signal RSRP (SS- RSRP) or Synchronization Signal RSRQ (SS-RSRQ). Measurements at the base station (e.g. NG- eNB or gNB) may include Uplink Angle of Arrival and Timing advance.

The application of these techniques has been further improved in 3GPP Release 17, enabling conventional 5G positioning services to meet the positioning requirements for commercial use cases and specifically lloT use cases as listed in Table 2.

Table 2

In a 5G System (5GS) architecture that is applicable to the positioning of a target UE, the target UE position is determined either by the target UE itself or by a location server (e.g. an LMF) depending on the applied positioning method. For exchanging the positioning related information (e.g. location related measurements, location estimates, assistance data), 3GPP TS 37.355 specifies LTE Positioning Protocol (LPP). LPP is a point-to-point positioning protocol used between the location server (e.g. an LMF) and the target UE that supports positioning and location related services for a target device.

Fig. 1 shows an exemplary 5GS architecture 100 for positioning a target UE 110. Fig. 1 includes 5GS components relevant for LPP message transfer and additional components for providing LCS services. The latter will be discussed in detail in the next chapter.

An exemplary LPP message transfer between an LMF 140 and a target UE 110 may include the following components: a target UE 110, an NG-RAN node 120 (e.g. an NG-eNB or a gNB), an Access Mobility Management Function (AMF) 130 and an LMF 140. LPP messages are carried as transparent Protocol Data Units (PDUs) across intermediate network interfaces using the appropriate protocol.

In a first step, the LMF 140 sends an LPP message to the AMF 130. The LPP message may be the Request Capabilities message to request the target UE 110 to send its positioning capabilities. The AMF 130 may transport the received LPP message to the NG-RAN node 120 by including the LPP message into the LPP message container of the Downlink Non Access Stratum (DL NAS) Transport message. In a next step, the NG-RAN node 120 may transport the received LPP message container to the target UE 110 by including the LPP message container into the Radio Resource Control (RRC) DLlnformationTransfer message as specified in 3GPP TS 38.331. Upon receiving the Request Capabilities LPP message, the target UE 110 may generate the Provide Capabilities LPP message as a response. The target UE 110 may then send the Provide Capabilities LPP message to the NG-RAN node 120 by including the LPP message into the RRC ULInformationTransfer message as specified in TS 38.331. Next, the NG-RAN node 120 may transport the LPP message received from the target UE 110 to the AMF 130 by including the LPP message into the LPP message container of the UL NAS Transport message. Finally, the AMF 130 may extract the LPP message from the received NAS message/LPP message container and send it to the LMF 140.

2. Location Services

The Location Services (LCS) feature in 3GPP provides the mechanisms to support mobile location services for operators, subscribers and third-party service providers. Examples of location-based services include emergency services, tracking services, location-based information services (navigation, city sightseeing, location dependent content broadcast, mobile yellow pages etc.). The location information may be requested by and reported to a client (application) associated with a UE, or by a client within or attached to the 5G core (5GC). Referring again to Fig. 1 , the full system depicted in the Figure shows an exemplary LCS architecture where an external LCS client 160 requests the 5GC for the current location of the target UE 110.

The external LCS Client 160 interacts with a Gateway Mobile Location Centre (GMLC) 150 for the purpose of obtaining location information for one or more target UEs 110. The LCS Client 160 may reside in a UE and may be implemented as Hardware or Software (e.g. an application). GMLC 150 is the first node an external LCS client 160 accesses in a PLMN and works as a location server for location information to an external application. The LMF 140 manages the overall co-ordination and scheduling of resources required for the location of a target UE 110 that is registered with or accessing the 5GC. The LMF 140 also calculates or verifies a final location and any velocity estimate and may estimate the achieved accuracy. The LMF 140 processes the location services request, which may include transferring assistance data to the target UE 110 to assist with UE-based and/or UE-assisted positioning and/or may include positioning of the target UE 110. The LMF 140 then returns the position estimate for the target UE 110 back to the AMF 130. In the case of a location service requested by an entity other than the AMF 130 (e.g., a GMLC 150 or a target UE 110), the AMF 130 returns the location result to this entity. In the control plane (C-plane) the LMF 140 works as a location server.

The AMF 130 contains functionality responsible for managing positioning for a target UE 110 for all types of location requests. The AMF 130 receives a request for some location services associated with a particular target UE 110 from another entity (e.g., GMLC 150 or the target UE 110) or the AMF 130 itself decides to initiate some location service on behalf of a particular target UE 110 (e.g., for an emergency call from the target UE 110). The AMF 130 then sends a location services request to an LMF 140.

The NG-RAN node (e.g. NG-eNB or gNB) 120 is involved in the handling of various positioning procedures including the positioning of a target UE 110, the provision of location related information not associated with a particular target UE 110 and the transfer of positioning messages between an AMF 130 or LMF 140 and a target UE 110.

The target UE 110 is the UE whose absolute position or relative position is to be obtained by the network or by the target UE 110 itself. A relative position is determined relative to a reference location and an absolute position is determined within an absolute coordinate framework such as a global coordinate system.

NRPPa is the C-plane radio network layer signalling protocol between an NG-RAN node (e.g. NG-eNB, gNB) 120 and the LMF 140.

The following types of location requests are specified in 3GPP:

• Network Induced Location Request (NI-LR): A serving AMF 130 for a target UE 110 initiates localization of the target UE 110 for a regulatory service (e.g. an emergency call from the target UE 110) or for verification of a target UE 110 location (country or international area) for NR satellite access. • Mobile Terminated Location Request (MT-LR): An LCS client 160 external to or internal to a serving PLMN sends a location request to the PLMN for the location of a target UE 110.

• Mobile Originated Location Request (MO-LR): A target UE 110 sends a request to a serving PLMN for location related information for the target UE 110 itself.

3. NR Sidelink Communication And Discovery

Modern positioning use cases such as Vehicle-to-everything (V2X) use cases, public safety regulation requirements, Hot and other commercial use cases demand even higher accuracy requirements as achievable with the techniques introduced in 3GPP release 17. A possible solution to achieve higher accuracy and lower latency is Sidelink (SL) positioning. The aim of SL positioning is to determine the position of a target UE 110 by using SL positioning methods such as RTT-type solutions using SL, SL-AoA and SL-TDOA. These positioning methods rely on direct device-to-device communication over Sidelink instead of communication with PLMN network entities (e.g. RAN node, or LMF). SL positioning methods are based on a PRS that is transmitted over the PC5 interface (SL PRS).

Sidelink was introduced in 3GPP Release 16 providing direct device-to-device communication between UEs based on 5G radio technology. Sidelink uses the New Radio air interface of the 5GS. Hence, Sidelink communication is based on the same radio technology (e.g. physical layer) as the air interface (Uu interface) for connecting the UE to a 5G enabled base station (e.g. an NG-eNB or a gNB). This means that Sidelink transmits data between UEs via the same transmitters and receivers (or in some cases transceivers), the same antennas and the same frequency range or at least part of the same frequency range as the Uu interface uses for sending and receiving data packages from a gNB or an NG-eNB. Sidelink provides a direct connection between UEs in proximity to each other. Direct connection in this context means that messages transmitted via Sidelink are not relayed from a first UE to a second UE via one or more NG-RAN nodes 120 (e.g. an NG-eNB or a gNB) through the network. Since Sidelink only works within a proximity range, a Sidelink device-to-device connection between a first UE and a second UE may not be possible when the two UEs are too far away from each other. In such a case, a Sidelink connection may be relayed via a third UE that is within the proximity range of the first and the second UE.

Sidelink (SL) communication was introduced to support Vehicle-to-everything (V2X) and non-V2X services. The interface used for SL communication (transmission/reception) between two UEs in proximity is denoted as PC5. Fig. 2 shows the scenarios which are supported for SL communication where two UEs are located in-coverage (IC), partial coverage (PC) and out-of- coverage (OOC) of a cell. In the OOC scenario, a first UE 220 and a second UE 230 are both outside of a coverage range 210 of an NG-RAN node (e.g. NG-eNB or gNB) 120. Hence, neither UE 220 nor UE 230 can establish a connection to the NG-RAN node 120 via the air interface (a Uu interface). However, the UEs 220 and 230 are within a proximity range from each other and are able to establish a direct device-to-device (UE-to-UE) connection 240 (e.g. a Sidelink connection via the PC5 interface). The OOC scenario is not limited to two UEs. The scenario may include three or more UEs that are outside of the coverage range of an NG-RAN node 120 but can connect to at least one of the other UEs via a direct device-to-device connection 240.

In the PC scenario at least one UE 220 is within the coverage range 210 of NG-RAN node 120. Another UE 230 is outside of the coverage range of the NG-RAN node 120 but within the proximity range of UE 220. UE 220 is connected via the air interface 250 (e.g. a Uu interface) to the NG-RAN and communicates with network services (e.g. LMF 140) or with other UEs via the PLMN network. Since UE 230 is outside of the coverage range of an NG-RAN, UE 230 is not (directly) connected to the PLMN network over an air interface connection 250 to an NG-RAN 120. However, UE 230 can communicate over a direct device-to-device connection 240 (e.g. a Sidelink connection via the PC5 interface) with UE 220. The scenario is not limited to two UEs and might instead include three or more UEs, where at least one UE is outside of an NG-RAN nodes coverage range 210 but within a proximity range of another UE within the NG-RAN nodes coverage range 210 such that the two UEs are able to communicate over a direct device-to-device connection 240 (e.g. a Sidelink connection via the PC5 interface).

The IC scenario relates to a situation where two or more UEs (e.g. UE 220 and UE 230) are within the coverage range 210 of an NG-RAN node 120 and are connected to the NG-RAN 120 node via the air interface 250 (e.g Uu interface). Hence, all UEs are able to communicate with network services (e.g. LMF 140) or with other UEs via the PLMN network. Additionally, at least some of the two or more UEs (e.g. UE 220 and UE 230) are within a proximity range from each other and are connected over a direct device-to-device connection 240 (e.g. a Sidelink connection via the PC5 interface), thereby being able to communicate with each other without relaying the communication over the PLMN network.

The transmission and reception of user traffic over the direct device-to-device interface 240 (e.g. PC5 interface) may be supported for unicast, groupcast and broadcast transmission. The transmission and reception of signalling traffic over the interface may be supported only for unicast transmission. A direct device-to-device connection 240 (e.g. Sidelink connection) over PC5 is defined as a logical connection between a pair of Source and Destination Layer-2 IDs. Source and Destination Layer-2 IDs identify the sender and the target of the direct device-to-device communication (e.g. Sidelink communication), respectively. For a cast type a corresponding pair of a Source Layer-2 ID and a Destination Layer-2 ID is used. The 3GPP Sidelink communication is based on the 3GPP Proximity-based Services (ProSe) feature.

In order to enable direct device-to-device communication (e.g. Sidelink communication) between UEs (e.g. UE 220 and UE 230) in proximity, a discovery procedure may need to be performed by the UEs (e.g. Sidelink discovery). The discovery procedure (e.g. Sidelink discovery procedure) may be used by UE(s) (e.g. UE 220) to discover or to be discovered by other UE(s) (e.g. UE 230) in proximity. For instance, UE 220 that wants to discover other UE(s) in proximity may transmit a discovery message over an interface for direct device-to-device communication (e.g. the PC5 interface). Other UE(s) (e.g. UE 230) in proximity may monitor the discovery message and if they want to be discovered they may respond with a discovery response message. After discovery, UE 220 can establish a direct device-to-device communication connection 240 (e.g. Sidelink connection) with each of the UE(s) (e.g. UE 230) which responded. NR Sidelink communication and discovery are described in 3GPP TS 23.304.

One of the challenges in developing robust procedures for SL positioning is that a SL positioning procedure has to address a number of different coverage scenarios (i.e. IC, PC and OOC scenarios) and as a result of these scenarios has to provide efficient support for both PC5- only-based and joint PC5-Uu-based operation scenarios.

4. Sidelink Positioning Terminologies

The embodiments enable UE positioning via direct device-to-device communication (e.g. Sidelink communication) in all three discussed coverage scenarios. This is achieved by coordinated interaction of a number of UEs or other devices. The below listed terms are used to refer to roles of particular UEs or other devices participating in a positioning session via direct device-to-device communication (e.g. Sidelink positioning session):

An initiator device initiates a positioning or ranging session (e.g. a Sidelink positioning or ranging session). In the IC or PC scenarios, an initiator device may be a network entity (e.g. NG- eNB, gNB, AMF, LMF), a UE or a roadside unit (RSU). In the OOC scenario an initiator device may be a UE or a UE-type RSU. A responder device responds to a positioning or ranging session (e.g. a Sidelink positioning or ranging session) from an initiator device. In the IC or PC scenarios, a responder device may be a network entity (e.g. NG-eNB, gNB, AMF, LMF), a UE or a roadside unit (RSU). In the OOC scenario a responder device may be a UE or a UE-type RSU.

A target UE (such as target UE 110) is the UE of interest whose position (absolute or relative) is to be obtained by the network (IC or PC scenarios) or by the UE itself (IC, PC and OOC scenarios).

An anchor UE supports the positioning of a target UE (e.g. target UE 110), e.g., by transmitting and/or receiving reference signals for positioning, providing positioning-related information, etc., over a direct device-to-device interface (e.g. the PC5 interface). An anchor UE may also be referred to as Sidelink Reference UE.

An assistant UE supports ranging/positioning via direct device-to-device connection 240 between an anchor UE and a target UE (e.g. target UE 110) over a direct device-to-device interface (e.g. a PC5 interface), when the direct ranging or positioning between the anchor UE and the target UE 110 cannot be supported (e.g. because the target UE 110 and anchor UE are not within the proximity range). The measurements, the results of the ranging, or the results of the positioning between the assistant UE and the anchor UE and that between the assistant UE and the target UE 110 are determined and used to derive the ranging or positioning results between the target UE 110 and the anchor UE.

A positioning server UE (e.g. Sidelink positioning server UE) offers location calculation for positioning and ranging based services (e.g. Sidelink positioning and ranging). A positioning server UE interacts with other UEs over a direct device-to-device interface (e.g. PC5 interface) as necessary in order to calculate the location of the target UE 110. The target UE 110 or anchor UE can act as a positioning server UE if the respective UEs support location calculation.

A positioning client UE or client UE (e.g. Sidelink positioning client UE) is a third-party UE, other than the anchor UE and the target UE 110, which initiates a ranging or positioning service request on behalf of the application residing on it. In some embodiments the target UE 110 initiates the ranging or positioning service request itself and thereby acts as a client UE.

In addition to the above-described roles of UE or devices within UE positioning procedures, the following terms are relevant for the subsequent discussion: Sidelink positioning refers to positioning of a UE using reference signals transmitted over direct device-to-device communication via a respective interface (e.g. Sidelink and the PC5 interface), to obtain absolute position, relative position, or ranging information.

Ranging refers to the determination of the distance and/or the direction (e.g. angle) between a target UE 110 and another entity, e.g. an anchor UE.

Fig. 3 depicts an exemplary configuration of a mobile telecommunications network apparatus 300 that may participate in the subsequently described procedures related to the determination of the location of a target UE 110 (e.g. positioning or ranging) in one of the roles described above. The depicted mobile telecommunications network apparatus 300 may act as a target UE (e.g. target UE 110), an anchor UE, a positioning server UE, an assistant UE and/or a client UE.

The mobile telecommunications network apparatus 300 comprises a memory 320, a processor 330, UE-to-UE interface 340, network interface 350 and radio unit 360. Memory 320 may be a volatile memory (e.g. DRAM or SRAM) or a non-volatile memory (e.g. SDD or HDD storage). Memory 320 stores computer-readable instructions 310. Processor 330 is configured to execute instructions 310. Executing the instructions 310 may cause processor 330 to implement positioning procedures such as the procedures presented in Figs. 4 to 7. Processor 330 controls network interface 350 and UE-to-UE interface 340. Network interface 350 is configured to connect the apparatus to a mobile telecommunications network (e.g. a PLMN such as an LTE network or a 5G NR network). Network interface 350 may provide an air interface 250 (e.g. a Uu interface) configured to connect the apparatus to a RAN node or an NG-RAN node (e.g. an eNB, NG-eNB or a gNB).

UE-to-UE interface 340 is configured to provide one or more direct device-to-device connections (e.g. Sidelink connections) to one or more other mobile telecommunications network apparatuses 300. UE-to-UE interface 340 may be a PC5 interface for providing Sidelink connections. A direct device-to-device connection does not involve network elements other than UEs. In particular, direct device-to-device connections do not include connections to the PLMN via an NG-RAN node (e.g. an eNB, NG-eNB or a gNB). Network interface 350 and/or UE-to-UE interface 340 may be implemented in software by computer-readable instructions 310. Alternatively or additionally, Network interface 350 and/or UE-to-UE interface 340 may be implemented fully or in part in specialized hardware such as specialized integrated circuits. Radio unit 360 provides the radio technology for implementing connections over network interface 350 and UE-to-UE interface 340. Radio unit 360 comprises transmitters and receivers or transceivers (not shown) configured to transmit and receive radio signals over one or more antennas 370. Antennas 370 are configured to transmit and receive radio signals within a frequency range that corresponds to the supported radio technology (e.g. LTE or 5G NR). Interfaces 350 and 340 are configured to provide communication and establish connections via radio unit 360 using the same radio technology (e.g. LTE or 5G NR).

5. Extending Device Positioning To Direct Device-To-Device Connections

In order to support positioning in operation scenarios where only direct device-to-device communication is available or where direct device-to-device communication is preferable (e.g. PC5-only-based operation scenarios) the following exemplary procedures for performing target LIE 110 location determination (e.g. positioning or ranging) are presented.

Fig. 4 relates to an exemplary positioning procedure initiated by a client LIE 430. The presented procedure can be performed using only direct device-to-device communication (e.g. PC5-only operation). The described procedure is applicable for all coverage scenarios. The following types of UEs are participating in the positioning session (e.g. Sidelink positioning session): target UE 405, anchor UE 410, positioning server UE 420, and client UE 430.

In some embodiments, target UE 405 may support only UE-assisted Sidelink positioning methods, where UE-assisted Sidelink positioning methods imply that the target UE 405 provides Sidelink positioning and/or Uu positioning measurements to another entity for positioning calculation. The determined position may comprise of absolute location information, relative location information, ranging information for a distance or ranging information for a direction.

In a first step, the client UE 430 wants to know the current location of the target UE 405. Client UE 430 starts a discovery procedure 440 (e.g. a Sidelink discovery procedure) via UE-to- UE interface 340 to discover other UEs in proximity. In one embodiment, client UE 430 discovers only the positioning server UE 420 in this discovery procedure. In another embodiment, client UE 430 may discover other UEs (e.g. the anchor UE 410 and/or the target UE 405) besides the positioning server UE 420 in this discovery procedure 440. Accordingly, steps 450 to 465 may be skipped depending on which UEs have been discovered in the discovery step 440.

In step 445, client UE 430 establishes a direct device-to-device communication connection (e.g. a Sidelink connection) via UE-to-UE interface 340 (e.g. PC5 interface) with the positioning server UE 420 and transmits a location request message to positioning server UE 420 via the established connection. The location request message comprises a request to determine the location of target UE 405. The location request message may be an MT-LR request message and may include a MT-LR Type parameter. The MT-LR Type parameter may support values to enable client UE 430 to request for the estimation of the ranging distance and ranging direction of target UE 405. The ranging distance may refer to the distance of the target UE 405 to another entity (e.g. anchor UE 410). Client UE 430 may request the estimation of the ranging distance by specifying the value “Ranging distance estimate” for the MT-LR Type parameter. Ranging direction may refer to the direction (e.g. an angle) between the target UE 405 and another entity (e.g. anchor UE 410). Client UE 430 may request the estimation of the ranging direction by specifying the value “Ranging direction estimate” for the MT-LR Type parameter.

The location request message comprises one or more accuracy parameters indicating a target accuracy for the location determination. The one or more accuracy parameters comprise at least one of a relative accuracy parameter, an absolute accuracy parameter for a distance determination (e.g. a ranging distance determination), and an absolute accuracy parameter for a direction determination (e.g. a ranging direction determination). The location request comprising a relative accuracy parameter relates to a relative location estimate request. The one or more accuracy parameters may be Quality of Service (QoS) parameters (e.g. LCS QoS parameters) and may comprise at least one of a horizontal relative accuracy parameter, a vertical relative accuracy parameter, a ranging distance absolute accuracy parameter, a ranging direction absolute accuracy parameter, a ranging distance relative accuracy parameter, and a ranging direction relative accuracy parameter. The horizontal relative accuracy parameter, the vertical relative accuracy parameter, the ranging distance absolute accuracy parameter, the ranging distance relative accuracy parameter, and the ranging direction relative accuracy parameter may have respective values that specify the respective accuracy in an appropriate unit of length (e.g. meter, centimeter, inches, or feet). The ranging direction absolute accuracy parameter and the ranging direction relative accuracy parameter may have values that specify the respective accuracy in an appropriate angle unit (e.g. degree or radians). The respective values of the accuracy parameters specify an accuracy (ora maximal error) that is to be achieved in determining the location of target UE 405.

If a relative location estimate or ranging estimate (e.g. a ranging distance estimate or a ranging direction estimate) is requested, then a reference location point may be needed to which the relative location, the ranging distance, and/or the ranging direction can be determined. In this case the location request message may contain a location of a reference location point. This reference location point may be e.g. the client UE’s 430 own position or another known UE position. An exemplary location request message may include the information as shown in Table 3 amongst other information.

Table 3

Assuming the client 430 did not already discover the anchor UE 410 in step 440, the positioning server UE 420 starts another discovery procedure 450 (e.g. a Sidelink discovery procedure) via its UE-to-UE interface 340 to discover target UE 405. In some embodiments the positioning server UE 420 is not able to directly discover target UE 405, instead the positioning server UE 420 is able to discover the anchor UE 410. In other implementations, one or more anchor UEs 410 may be discovered. The number of anchor UE(s) 410, which may be discovered, may depend on the positioning method configured by the positioning server UE 420, e.g., SL- TDoA, SL-RTT variants (single-sided or double-sided RTT). In other embodiments, target UE 405 is discovered in step 450, in this case steps 455 to 465 may be skipped.

In step 455, the positioning server UE 420 establishes a direct device-to-device communication connection (e.g. a Sidelink connection) via UE-to-UE interface 340 (e.g. PC5 interface) with the anchor UE 410 and sends a positioning request message (e.g. a Sidelink positioning request message) to anchor UE 410 via the established connection. The request message includes the request to discover target UE 405 for determining the target UEs location (e.g. Sidelink positioning). The positioning request message may be a Sidelink Positioning Protocol (SLPP) message e.g. an SL positioning request message. In one implementation, the positioning request message contains a parameter “Discovery type” with value “SL positioning”. In another implementation, the request message further contains an embedded discovery message. Generally, the positioning request message (e.g. Sidelink positioning request message) may be used by a first (SL) UE (in this case, a positioning server UE 420) to request a second (SL) UE (in this case, the anchor UE 410) to discover a third (SL) UE (in this case, the target UE 405) for (SL) positioning.

In step 460, anchor UE 410 starts another discovery procedure (e.g. a Sidelink discovery procedure) via its UE-to-UE interface 340 to discover the target UE 405. After discovery, the anchor UE 410 establishes a direct device-to-device communication connection (e.g. a Sidelink connection) via UE-to-UE interface 340 (e.g. PC5 interface) with the target UE 405.

In step 465, anchor UE 410 sends a positioning response message (e.g. a Sidelink positioning response message) to positioning server UE 420 via the established direct device-to- device connection. The positioning response message comprises an indication that target UE 405 has been discovered. The positioning response message may be a SLPP message e.g. an SL positioning response message. Generally, the positioning response message (e.g. Sidelink positioning request message) may be used by a first (SL) UE (in this case, anchor UE 410) to indicate to a second (SL) UE (in this case, positioning server UE 420) that a third (SL) UE (in this case, target UE 405) has been discovered for (SL) positioning.

Subsequently, the positioning server UE 420, anchor UE 410 and target UE 405 perform positioning procedures in step 470. These procedures may include an SL positioning capability transfer between the target UE 405 and the positioning server UE 420. Furthermore, in some embodiments, target UE 405 or positioning server UE 420 may transmit an assistance data activation request to anchor UE 410 via the respective established direct device-to-device connection. The assistance data activation request message may include a request to activate the transmission of assistance data by transmitting a positioning reference signal (PRS) to target UE 405. The assistance data activation request may also include the characteristics of the PRS (e.g. an SL-PRS) transmission, e.g. start time and duration, frequency range (FR1/FR2), resource bandwidth, comb size, resource repetition, muting configuration, power control parameters etc. The assistance data activation request message may be an SLPP message e.g. an SL assistance data activation request. Generally, the assistance data activation request is used by a first (SL) UE (in this case, target UE 405 or positioning server UE 420) to request a second (SL) UE (in this case, anchor UE 410) to transmit (SL-)PRS for (SL) positioning. The (SL-)PRS is a signal that is received by target UE 405 (or in some cases by an assistant UE) from anchor UE 410 via the established direct device-to-device connection and enables the target UE 405 (or the assistant UE) to perform measurements (e.g. AoD, ToF, TDOA or RTT) based on the PRS (e.g. SL-PRS) that allow the calculation of a distance to anchor UE 410 or a direction (e.g. an angle) to anchor UE 410. In some cases, depending on the applied positioning method (e.g. an SL positioning method), a plurality of anchor UEs 410 are involved in the target UE 405 positioning (e.g. the SL- TDOA positioning method requires multiple anchor UEs 410) and target UE 405 may request and receive PRS from each of the plurality of anchor UEs 410 to perform the measurements. Based on these measurements the positioning server UE 420 determines the absolute or relative location of target UE 405. In response to receiving the assistance data activation request, anchor UE 410 selects a configuration type for the PRS e.g. in accordance with its positioning capabilities and current load. The configuration type determines the characteristics (i.e. the properties) of the PRS. The anchor UE 410 then transmits the PRS in accordance with the selected configuration type. The target UE 405 receives the PRS via the direct device-to-device interface (e.g. the PC5 interface), performs the measurements and transmits the result of the measurements to positioning server UE 420, which then may determine the requested location of target UE 405.

Depending on the coverage situation (e.g. IC or PC scenarios) the location determination may be additionally assisted by the PLMN network (e.g. by LMF 140 or RAN 120) or may be alternatively entirely performed by a PLMN location function (e.g. by LMF 140).

After determining the location of target UE 405, the positioning server UE 420 transmits in step 475 a location response message to client UE 430 over the established direct device-to- device connection. The location response message includes the requested and determined location information for the target UE 405. The location response message may be an MT-LR response message and may include one or more accuracy parameters (e.g. included in a LCS MT-LR Result parameter) indicating an achieved accuracy for the location determination. The one or more accuracy parameters comprise at least one of a relative accuracy parameter, an absolute accuracy parameter for a distance determination (e.g. a ranging distance determination), and an absolute accuracy parameter for a direction determination (e.g. a ranging direction determination). The one or more accuracy parameters may comprise at least one of a horizontal relative accuracy parameter, a vertical relative accuracy parameter, a ranging distance absolute accuracy parameter, a ranging direction absolute accuracy parameter, a ranging distance relative accuracy parameter, and a ranging direction relative accuracy parameter. The horizontal relative accuracy parameter, the vertical relative accuracy parameter, the ranging distance absolute accuracy parameter, the ranging distance relative accuracy parameter, and the ranging direction relative accuracy parameter may have respective values that specify the respective accuracy in an appropriate unit of length (e.g. meter, centimeter, inches, or feet). The ranging direction absolute accuracy parameter and the ranging direction relative accuracy parameter may have values that specify the respective accuracy in an appropriate angle unit (e.g. degree or radians). The respective values of the accuracy parameters specify an accuracy (or a maximal error) that has been achieved in the location determination of target UE 405.

In one embodiment, the various discovery procedures performed in steps 440, 450 and 460 may be performed jointly in one step, with the aim of discovering the desired UEs (positioning server UE 420, one or more anchor UEs 410, target UE 405) in a single shot. If any of the UEs cannot be discovered in a first try, then the discovery procedure may also be repeated based on certain criteria, including the periodicity of discovery procedures, number of configured times in which to initiate a discovery procedure, etc.

Turning now to Fig. 5, which shows a signal flow for an exemplary positioning procedure initiated by a target UE 502 for determining its own location based on direct device-to-device connections (e.g. SL connections) between a number of UEs. The presented procedure can be performed using only direct device-to-device communication (e.g. PC5-only operation). The described procedure is applicable for all coverage scenarios. The following types of UEs are participating in the positioning session (e.g. a Sidelink positioning session): target UE 502 (which also acts as a client UE), anchor UE 504, positioning server UE 506.

In some embodiments target UE 502 may support only UE-assisted SL positioning methods, where UE-assisted SL positioning methods imply that the target UE 502 provides Sidelink positioning and/or Uu positioning measurements to another entity for the positioning calculation. The determined position may comprise of absolute location information, relative location information, ranging information for a distance, or ranging information for a direction.

In a first step, target UE 502 wants to know its own current location. Target UE 502 starts a discovery procedure 510 (e.g. a Sidelink discovery procedure) via its UE-to-UE interface 340 to discover other UEs in proximity. In one embodiment, target UE 502 discovers only anchor UE 504. In another embodiment, target UE 502 may discover other UEs (e.g. additional anchor UEs 504 and/or positioning server UE 506) besides the anchor UE 504 in discovery procedure 510. Accordingly, steps 515 to 525 may be skipped depending on whether or not the positioning Server UE 506 has been discovered in the first discovery procedure in step 510.

Subsequent to the discovery of anchor UE 504, target UE 502 establishes a direct device- to-device communication connection (e.g. a Sidelink connection) via UE-to-UE interface 340 (e.g. PC5 interface) with anchor UE 504. Assuming the target UE 502 did not already discover the positioning server UE 506 in step 510, target UE 502 sends a positioning request message (e.g. a Sidelink positioning request message) in step 515 to anchor UE 504 via the established connection. The request message includes the request to discover positioning server UE 506 for determining the target UEs location. The positioning request message may be an Sidelink Positioning Protocol (SLPP) message e.g. an SL positioning request message. In one implementation, the positioning request message contains a parameter “Discovery type” with value “SL positioning”. In another implementation, the request message further contains an embedded discovery message. Generally, the positioning request message (e.g. the Sidelink positioning request message) may be used by a first (SL) UE (in this case, target UE 502) to request a second (SL) UE (in this case, anchor UE 504) to discover a third (SL) UE (in this case, positioning server UE 506) for (SL) positioning.

In step 520, anchor UE 504 starts another discovery procedure (e.g. a Sidelink discovery procedure) via its UE-to-UE interface 340 to discover the positioning server UE 506. After the discovery of positioning server UE 506, anchor UE 504 establishes a direct device-to-device communication connection (e.g. a Sidelink connection) via its UE-to-UE interface 340 (e.g. a PC5 interface) with positioning server UE 506.

Anchor UE 504 in step 525 transmits a positioning response message (e.g. an Sidelink positioning response message) to target UE 502 comprising an indication that positioning server UE 506 has been discovered. The positioning response message may be an SLPP message e.g. an SL positioning response message. Generally, the positioning response message (e.g. Sidelink positioning request message) may be used by a first (SL) UE (in this case, anchor UE 504) to indicate to a second (SL) UE (in this case, target UE 502) that a third (SL) UE (in this case, positioning server UE 506) has been discovered for positioning (e.g. SL positioning).

In step 530, target UE 502 transmits a location request message to anchor UE 504 via the earlier established connection. The location request message comprises a request to determine the location of target UE 502 itself. The location request message may be an MO-LR request message and may include an MO-LR Type parameter. The MO-LR Type parameter may support values to enable target UE 502 to request the estimation of the ranging distance and ranging direction of target UE 502. Ranging distance may refer to the distance of the target UE 502 to another entity (e.g. anchor UE 504). Target UE 502 may request the estimation of the ranging distance by specifying the value “Ranging distance estimate” for the MO-LR Type parameter. Ranging direction may refer to the direction (e.g. an angle) between target UE 502 and another entity (e.g. anchor UE 504). Target UE 502 may request the estimation of the ranging direction by specifying the value “Ranging direction estimate” for the MO-LR Type parameter. The location request message comprises one or more accuracy parameters indicating a target accuracy for the location determination. The one or more accuracy parameters comprise at least one of a relative accuracy parameter, an absolute accuracy parameter for a distance determination (e.g. a ranging distance determination), and an absolute accuracy parameter for a direction determination (e.g. a ranging direction determination). The location request comprising a relative accuracy parameter relates to a relative location estimate request. The one or more accuracy parameters may be Quality of Service (QoS) parameters (e.g. LCS QoS parameters) and may comprise at least one of a horizontal relative accuracy parameter, a vertical relative accuracy parameter, a ranging distance absolute accuracy parameter, a ranging direction absolute accuracy parameter, a ranging distance relative accuracy parameter, and a ranging direction relative accuracy parameter. The horizontal relative accuracy parameter, the vertical relative accuracy parameter, the ranging distance absolute accuracy parameter, the ranging distance relative accuracy parameter, and the ranging direction relative accuracy parameter may have respective values that specify the respective accuracy in an appropriate unit of length (e.g. meter, centimeter, inches, or feet). The ranging direction absolute accuracy parameter and the ranging direction relative accuracy parameter may have values that specify the respective accuracy in an appropriate angle unit (e.g. degree or radians). The respective values of the accuracy parameters specify an accuracy (or a maximal error) that is to be achieved in the location determination of target UE 502.

If a relative location estimate or ranging estimate (e.g. a ranging distance estimate or a ranging direction estimate) is requested then a reference location point is needed to which the relative location, the ranging distance, and/or the ranging direction can be determined. In this case the location request message may contain a location of a reference location point. This reference location point may be e.g. the position of the anchor UE 504 or another known UE position. An exemplary location request message may include the information as shown in Table 4 amongst other information. Response time Value in seconds

Location Type

Table 4

In step 535, anchor UE 504 forwards the request message to positioning server UE 506.

Subsequently, positioning server UE 506, anchor UE 504 and target UE 502 perform positioning procedures in step 540. These procedures may include an SL positioning capability transfer between the target UE 502 and the positioning server UE 506. Furthermore, in some embodiments, target UE 502 or positioning server UE 506 may transmit an assistance data activation request to anchor UE 504 via the respective established direct device-to-device connection. The assistance data activation request message may include a request to activate the transmission of assistance data by transmitting a positioning reference signal (PRS) to target UE 502. The assistance data activation request may also include the characteristics of the PRS (e.g. SL-PRS) transmission, e.g. start time and duration, frequency range (FR1/FR2), resource bandwidth, comb size, resource repetition, muting configuration, power control parameters etc. The assistance data activation request message may be an SLPP message e.g. an SL assistance data activation request. Generally, the assistance data activation request is used by a first (SL) UE (in this case, target UE 502 or positioning server UE 506) to request a second (SL) UE (in this case, anchor UE 504) to transmit (SL-)PRS for (SL) positioning. The (SL-)PRS is a signal that is received by target UE 502 (or in some cases by an assistant UE) from anchor UE 504 via the established direct device-to-device connection and enables the target UE 502 (or the assistant UE) to perform measurements (e.g. AoD, ToF, TDOA or RTT) that allow the calculation of a distance to anchor UE 504 or a direction (e.g. an angle) to anchor UE 504. In some cases, depending on the applied positioning method (e.g. a SL positioning method), a plurality of anchor UEs 504 are involved in the target UE positioning (e.g. the SL-TDOA positioning method requires multiple anchor UEs 504) and target UE 502 may request and receive PRS from each of the plurality of anchor UEs 504 to perform the measurements. Based on these measurements the positioning server UE 506 determines the absolute or relative location of target UE 502. In response to receiving the assistance data activation request, anchor UE 504 selects a configuration type for the PRS e.g. in accordance with its positioning capabilities and current load. The configuration type determines the characteristics (i.e. the properties) of the PRS. The anchor UE 504 then transmits the PRS in accordance with the selected configuration type. The target UE 502 receives the PRS via the direct device-to-device interface, performs the measurements and transmits the result of the measurements to positioning server UE 506, which then may determine the requested location of target UE 502. Depending on the coverage situation (e.g. IC or PC scenarios) the location determination may be additionally assisted by the PLMN network (e.g. by LMF 140 or RAN 120) or may be alternatively entirely performed by a PLMN location function (e.g. by LMF 140).

After determining the location of target UE 502, the positioning server UE 506 transmits in step 545 a location response message to anchor UE 504 over the established direct device-to- device connection. The location response message includes the requested and determined location information of target UE 502. The location response message may be an MO-LR response message and may include one or more accuracy parameters (e.g. included in an LCS MO-LR Result parameter) indicating an achieved accuracy for the location determination. The one or more accuracy parameters comprise at least one of a relative accuracy parameter, an absolute accuracy parameter for a distance determination (e.g. a ranging distance determination), and an absolute accuracy parameter for a direction determination (e.g. a ranging direction determination). The one or more accuracy parameters may comprise at least one of a horizontal relative accuracy parameter, a vertical relative accuracy parameter, a ranging distance absolute accuracy parameter, a ranging direction absolute accuracy parameter, a ranging distance relative accuracy parameter, and a ranging direction relative accuracy parameter. The horizontal relative accuracy parameter, the vertical relative accuracy parameter, the ranging distance absolute accuracy parameter, the ranging distance relative accuracy parameter, and the ranging direction relative accuracy parameter may have respective values that specify the respective accuracy in an appropriate unit of length (e.g. meter, centimeter, inches, or feet). The ranging direction absolute accuracy parameter and the ranging direction relative accuracy parameter may have values that specify the respective accuracy in an appropriate angle unit (e.g. degree or radians). The respective values of the accuracy parameters specify an accuracy (or a maximal error) that has been achieved in the location determination of target UE 502. In step 550, anchor UE 504 forwards the response message to target UE 502.

Fig. 6 illustrates a signal flow for an exemplary positioning procedure initiated by a target UE 604. The presented procedure can be performed using only direct device-to-device communication (e.g. PC5-only operation). The described procedure is applicable for all coverage scenarios. The following types of UEs are participating in the positioning session (e.g. Sidelink positioning session): target UE 604 and anchor UE 608. Target UE 604 also acts as a positioning server UE and a client UE. In some embodiments, target UE 604 may support UE-assisted and UE-based SL positioning methods, where UE-assisted SL positioning methods imply that target UE 604 provides SL positioning and/or Uu positioning measurements to another entity for positioning calculation, while UE-based SL positioning methods imply that target UE 604 performs positioning calculation internally (acting as a positioning server UE). The determined position may comprise of absolute location information, relative location information, ranging information for a distance, or ranging information for a direction.

In a first step, target UE 604 wants to know its own current location. Since target UE 604 works also as a positioning server UE (e.g. an SL positioning server UE), only the support of anchor UE(s) 608 is required for the target UE positioning. Target UE 604 starts a discovery procedure 610 (e.g. a Sidelink discovery procedure) via its UE-to-UE interface 340 to discover one or more anchor UEs 608 in proximity.

Subsequent to the discovery of anchor UE 608, target UE 604 establishes a direct device- to-device communication connection (e.g. a Sidelink connection) via its UE-to-UE interface 340 (e.g. PC5 interface) with one or more anchor UEs 608. In step 620, target UE 604 transmits an assistance data activation request to anchor UE 608 via the established direct device-to-device connection. The assistance data activation request message includes a request to activate the transmission of assistance data by transmitting a positioning reference signal (PRS) to target UE 604. The assistance data activation request may also include the characteristics of the PRS (e.g. SL-PRS) transmission, e.g. start time and duration, frequency range (FR1/FR2), resource bandwidth, comb size, resource repetition, muting configuration, power control parameters etc. The assistance data activation request message may be an SLPP message e.g. an SL assistance data activation request. Generally, the assistance data activation request is used by a first (SL) UE (in this case, target UE 604) to request a second (SL) UE (in this case, anchor UE 608) to transmit (SL-)PRS for (SL) positioning. In response to receiving the assistance data activation request, anchor UE 608 selects a configuration type for the PRS e.g. in accordance with its positioning capabilities and current load. The configuration type determines the characteristics (i.e. the properties) of the PRS. In some implementations, the request message may be conveyed using the SLPP RequestAssistanceData message.

In step 630, a data activation response may be optionally transmitted from anchor UE 608 to the target UE 604 over the established connection. The response message may include the PRS configuration type that has been selected by anchor UE 608 in accordance with its e.g. (SL) positioning capabilities and/or current load. In some implementations, the response message may be conveyed using the SLPP ProvideAssistanceData message. In another implementation, the SL assistance data may be provided to target UE 604 in an unsolicited manner.

In step 640, anchor UE 608 transmits the PRS (e.g. a SL-PRS) to target UE 604 via the established direct device-to-device connection (e.g. connection 240) in accordance with the selected configuration type. The PRS is configured to enable the target UE 604 to perform measurements based on the PRS (e.g. AoD, ToF, TDOA or RTT) that allow the calculation of a distance to anchor UE 608 or a direction (e.g. an angle) to anchor UE 608.

In step 650, target UE 604 receives the PRS (e.g. a SL-PRS) from anchor UE 608 and performs the measurements based on the PRS (e.g. AoD, ToF, TDOA or RTT), allowing the calculation of a distance to anchor UE 608 or a direction (e.g. an angle) to anchor UE 608. In some cases, depending on the applied positioning method (e.g. an SL positioning method), a plurality of anchor UEs 608 are involved in the target UE positioning (e.g. the SL-TDOA positioning method requires multiple anchor UEs 608) and target UE 604 may request and receive PRS from each of the plurality of anchor UEs 608 to perform the measurements. Target UE 604 acting as a positioning server UE may process the measurements to determine the absolute or relative location of target UE 604.

Turning now to an exemplary positioning procedure initiated by a client UE 706 as illustrated in Fig. 7. The presented procedure can be performed using only direct device-to-device communication (e.g. PC5-only operation). The described procedure is applicable for all coverage scenarios. The following types of UEs are participating in the positioning session (e.g. Sidelink positioning session): target UE 702, anchor UE 704, and client UE 706. Target UE 702 also acts as a positioning server UE. In some embodiments, target UE 702 may support UE-assisted and UE-based SL positioning methods, where UE-assisted SL positioning methods imply that target UE 702 provides SL positioning and/or Uu positioning measurements to another entity for positioning calculation, while UE-based SL positioning methods imply that target UE 702 performs positioning calculation internally (acting as a positioning server UE). The determined position may comprise of absolute location information, relative location information, ranging information for a distance, or ranging information for a direction.

In a first step, the client UE 706 wants to know the current location of the target UE 702. The client UE 706 starts a discovery procedure (e.g. a SL discovery procedure) 710 to discover other UEs in proximity. The remaining procedure assumes that the client UE 706 was able to discover the target UE 702 and the anchor UE 704. However, as described with respect to Fig. 4, client UE 706 may not find the target UE 702 in some cases in the discovery process as the target UE 702 may for instance not be in the proximity range for a direct device-to-device connection. In this case additional discovery steps e.g. according to steps 455, 460 and 465 or 515, 520 and 525 may be necessary to discover all UEs that are needed to perform the positioning process, in particular to discover target UE 702. In step 720 client UE 706 establishes a direct device-to-device communication connection (e.g. a Sidelink connection) via UE-to-UE interface 340 (e.g. PC5 interface) with the target UE 702 acting as a positioning server UE and transmits a location request message to the target UE 702 via the established connection. The location request message comprises a request to determine the location of target UE 702. The location request message has the same properties as the location request message transmitted in step 445 between the client UE 430 and positioning server UE 420. In particular, the location request message may comprise accuracy parameters and may be an MT-LR request as described with reference to step 445 of Fig. 4.

In step 730, target UE 702 acting as a positioning server UE establishes a direct device- to-device communication connection (e.g. a Sidelink connection) via its UE-to-UE interface 340 (e.g. PC5 interface) with anchor UE 704 and transmits an assistance data activation request to anchor UE 704 via the established direct device-to-device connection. The assistance data activation request message includes a request to activate the transmission of assistance data by transmitting a positioning reference signal (PRS) to target UE 702. The assistance data activation request may also include the characteristics of the PRS (e.g. SL-PRS) transmission, e.g. start time and duration, frequency range (FR1/FR2), resource bandwidth, comb size, resource repetition, muting configuration, power control parameters etc. The assistance data activation request message may be an SLPP message e.g. an SL assistance data activation request. Generally, the assistance data activation request is used by a first (SL) UE (in this case, target UE 702 acting as a positioning server UE) to request a second (SL) UE (in this case, anchor UE 704) to transmit a (SL-)PRS for (SL) positioning. In response to receiving the assistance data activation request, anchor UE 704 selects a configuration type for the PRS e.g. in accordance with its positioning capabilities and/or current load. The configuration type determines the characteristics (i.e. the properties) of the PRS. In some implementations, the request message may be conveyed using the SLPP RequestAssistanceData message.

In step 740, a data activation response may be optionally transmitted from anchor UE 704 to the target UE 702 over the established connection. The response message may include the PRS configuration type that has been selected by anchor UE 704. In some implementations, the response message may be conveyed using the SLPP ProvideAssistanceData message. In another implementation, the SL assistance data may be provided to target UE 702 in an unsolicited manner.

In step 750, anchor UE 704 transmits the PRS (e.g. an SL-PRS) to target UE 702 via the established direct device-to-device connection (e.g. connection 240) in accordance with the selected configuration type. The PRS is configured to enable the target UE 702 to perform measurements based on the PRS (e.g. AoD, ToF, TDOA or RTT) that allow the calculation of a distance to anchor UE 704 or a direction (e.g. an angle) to anchor UE 704.

In step 760, target UE 702 receives the PRS (e.g. an SL-PRS) from anchor UE 704 via the established direct device-to-device connection and performs the measurements based on the PRS (e.g. AoD, ToF, TDOA or RTT), allowing the calculation of a distance to anchor UE 704 or a direction (e.g. an angle) to anchor UE 704. In some cases, depending on the applied positioning method (e.g. an SL positioning method), a plurality of anchor UEs 704 are involved in the target UE 702 positioning (e.g. the SL-TDOA positioning method requires multiple anchor UEs 704) and target UE 702 may request and receive PRS from each of the plurality of anchor UEs 704 to perform the measurements. Target UE 702 acting as a positioning server UE may process the measurements to determine the absolute or relative location of target UE 702.

After determining the location of target UE 702, target UE 702 acting as a positioning server UE transmits in step 770 a location response message to client UE 706 over the established direct device-to-device connections. Note, that in case the client UE 706 was not able to detect the target UE 702 in the first discovery step, the client UE 706 may not have a direct connection to the target UE 702. In this case, the anchor UE 704 may have discovered the target UE 702 in a second discovery step (e.g. according to 455, 460 and 465 of Fig. 4) and may have established a direct device-to-device connection to target UE 702. In this situation, target UE 702 acting as a positioning server UE may transmit the location response message to anchor UE 704 over the established direct device-to-device connection and anchor UE 704 may forward the location response message to client UE 706 via their direct device-to-device connection.

In any case, the location response message includes the requested and determined location information of target UE 702. Furthermore, the location response message may have the same properties as the location response message of step 475. Specifically, the location response message may be an MT-LR response message and may include one or more accuracy parameters (e.g. included in an LCS MT-LR Result parameter) indicating an achieved accuracy for the location determination as described in more detail with respect to step 475 of Fig. 4.

The methods and apparatuses presented in the above-discussed embodiments enable the efficient determinations of the relative or absolute location of a mobile telecommunications network apparatus (i.e. a UE such as target UE 702) without relying on network location services (such as LMF 140). As a result, the discussed embodiments support positioning (e.g. SL positioning) in all communication scenarios (i.e. IC, PC and OOC scenarios), including PC5-only-based operation scenarios. Additionally, various types of UEs supporting direct device-to-device connections (e.g. SL UEs support SL connections via a PC5 interface) participating in a positioning session (e.g. an SL positioning session) can be supported. The described embodiments support stable positioning (e.g. SL positioning) even in one of the following cases: a positioning server UE (e.g. a SL positioning server UE) is out-of-coverage, no SL positioning and/or ranging capable LMF 140 is available, LMF 140 decides that a positioning server UE (e.g. a SL positioning server UE) executes the result calculation, a positioning server UE (e.g. a SL positioning server UE) decides on its own to do PC5-only positioning and/or ranging, and/or a positioning server UE (e.g. an SL positioning server UE) has no LPP capabilities but only SLPP capabilities. It is further noted that although the described embodiments enable target UE positioning independent of network-based location or positioning services (such as LMF 140), in cases where all (IC scenario) or some (PC scenario) of the UEs which take part in the described embodiments (e.g. target UEs 405, 502, 604, 702, anchor UEs 410, 504, 608, 704, positioning server UEs 420, 506 and/or client UEs 430, 706) are within a coverage range of an NG-RAN node (e.g. an NG-eNB or a gNB) the target UE location determination may be additionally supported by network location services (e.g. LMF 140).

In the above description of Fig. 4 to 7 target UEs 405, 502, 604, 702 correspond to each other in the sense that they all comply with the role of a target UE as defined in chapter 4. The same applies to anchor UEs 410, 504, 608 and 704 with respect to the role as an anchor UE. Similarly, positioning server UEs 420, 506 also correspond to each other. Although they have combined functionalities, with respect to their functionality as positioning server UEs as defined in chapter 4, UEs 604 and 702 correspond to each other and to positioning server UEs 420, 506. Finally, client UEs 430, 706 and target UEs 502 and 702 having combined functionalities correspond to each other in their functionality as client UEs. It is further noted that all the above UEs may be implemented in accordance with mobile telecommunications network apparatus 300. The terms mobile telecommunications network apparatus and communication device are used interchangeably in this description. Further, combined functionalities implemented in the target UEs 604 and 702 of the processes described with respect to Figs. 6 and 7 may be implemented as separate UEs having only one of the combined roles. Hence, the functionalities performed by target UE 604 of figure 6 could alternatively be implemented by a target UE and a separate client UE. Similarly, the functionalities performed by target UE 702 of figure 7 could alternatively be implemented by three separate UEs: a target UE, a client UE and a positioning server UE.

The above described features may be implemented as a computer-implemented method by different mobile telecommunications network apparatuses in a mobile telecommunications network. Additionally, the computer-implemented methods may be embodied as instructions on a computer-readable medium. Accordingly, the present description relates to computer- implemented methods for performing target UE positioning and to computer-readable media and mobile telecommunications network apparatuses that implement these methods. All the above described network functions (e.g. AMF 130 or LMF 140) may be computer functions that run on either a standalone computer server that implements the corresponding functions or different network functions that may share one or more computer servers.

The embodiments presented herein are not to be understood as restricted to only the described specific combination of features performed by hardware and/or software entities. In particular, other possible embodiments may comprise any combination of features from described embodiments. Moreover, features described in the context of a certain embodiment may also be comprised in other embodiments without being explicitly presented as such. Embodiments may comprise more or less features than described. Further, software and hardware entities may perform more or less features than described in certain embodiments. A software or hardware entity may also perform features that are described in the context of other software or hardware entities. In addition, steps described in a certain order in the context of a method may be performed in any other reasonable order. It is to be understood that the present description encompasses all embodiments that arise from these alternative combinations of features and entities.

While the invention has been described with respect to the physical embodiments constructed in accordance therewith, it will be apparent to those skilled in the art that various modifications, variations and improvements of the present invention may be made in light of the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the disclosure. In addition, those areas in which it is believed that those of ordinary skill in the art are familiar, have not been described herein in order to not unnecessarily obscure the invention described herein. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrative embodiments, but only by the scope of the appended claims.

6. List of Acronyms

3GPP 3^rd Generation Partnership Project

5GS 5G System

A-GNSS Assisted GNSS

AMF Access and Mobility Management Function

AoA Angle of Arrival

AoD Angle of Departure CM Connection Management

DL Downlink

DL TDOA Downlink Time Difference of Arrival

E-CID Enhanced Cell ID

FR Frequency Range

GMLC Gateway Mobile Location Centre

GNSS Global Navigation Satellite System

GPSI Generic Public Subscription Identifier

HW Hardware

IC In-coverage

HoT Industrial IoT

IOT Internet of Things

KPI Key Performance Indicator

LCS Location Services

LMF Location Management Function

LPP LTE Positioning Protocol

LTE Long Term Evolution

MO-LR Mobile-Originated Location request

MT-LR Mobile-Terminated Location request

Multi-RTT Multi Round Trip Time

NAS Non Access Stratum

NG-RAN Next Generation RAN

NI-LR Network Induced Location Request

NR New Radio

NRPPa NR Positioning Protocol A

OOC Out-of-coverage

PC Partial coverage

PDU Protocol Data Unit

PHY Physical Layer

PLMN Public Land Mobile Network

PPP Precise Point Positioning

ProSe Proximity-based services

PRS Positioning Reference Signal

PSAP Public Safety Answering Point

QoS Quality of Service RAN Radio Access Network

RAT Radio Access Technology

RRC Radio Resource Control

RSU Roadside Unit RTK Real-Time Kinematic

SL Sidelink

SLPP Sidelink Positioning Protocol

SUPI Subscription Permanent Identifier

SW Software TDOA Time Difference of Arrival

ToF Time of Flight

TTFF Time To First Fix

UE User Equipment

UL Uplink

V2X Vehicle-to-Everything

WID Work Item Description

Claims

1. A mobile telecommunications network apparatus including a first interface configured to provide communication with a mobile telecommunications network via a radio unit, and a second interface configured to provide direct device-to-device communication within a proximity range via the radio unit, the apparatus comprising: one or more processors configured to execute computer-readable instructions for implementing a determination of a target communication device location, the instructions causing the one or more processors to: establish a direct device-to-device connection to a communication device within the proximity range via the second interface; transmit a location request message to the communication device via the established connection, the location request message comprising a request to determine the location of the target communication device and one or more accuracy parameters indicating a target accuracy for the location determination, wherein the one or more accuracy parameters comprise at least one of a relative accuracy parameter, an absolute accuracy parameter for a distance determination, and an absolute accuracy parameter for a direction determination; and receive a location response message from the communication device via the established connection, the location response message comprising data indicating the location of the target communication device determined in accordance with the one or more accuracy parameters.

2. The mobile telecommunications network apparatus of claim 1 , wherein the mobile telecommunications network apparatus is the target communication device.

3. The mobile telecommunications network apparatus of claim 2, wherein the communication device is an anchor UE configured to support the determination of the location of the target communication device, and wherein the instructions further cause the one or more processors to: transmit a positioning request message to the anchor UE via the established connection, the positioning request message including a request to discover another communication device within the proximity range, wherein the positioning request message is configured to cause the anchor UE to discover the other communication device in accordance with the received positioning request message; and receive a positioning response message from the anchor UE via the established connection indicating that the other communication device has been discovered.

4. The mobile telecommunications network apparatus of claim 2 or 3, wherein the communication device is an anchor UE configured to support the determination of the location of the target communication device, and wherein the instructions further cause the one or more processors to: receive a positioning reference signal from the anchor UE via the established connection; and perform measurements based on the positioning reference signal for determining the location of the target communication device.

5. The mobile telecommunications network apparatus of claim 1 , wherein the mobile telecommunications network apparatus is different from the target communication device.

6. The mobile telecommunications network apparatus of any one of the preceding claims, wherein the request to determine the location of the target communication device comprises at least one of a request to determine a ranging distance estimate for the target communication device and a request to determine a ranging direction estimate for the target communication device.

7. The mobile telecommunications network apparatus of any one of the preceding claims, wherein the communication device is a positioning server UE configured to determine the location of the target communication device, and wherein the location request message is configured to cause the communication device to determine the location of the target communication device in accordance with the one or more accuracy parameters.

8. The mobile telecommunications network apparatus of any one of the preceding claims, wherein the one or more accuracy parameters are Quality of Service, QoS parameters and comprise at least one of a horizontal relative accuracy parameter, a vertical relative accuracy parameter, a ranging distance absolute accuracy parameter, a ranging distance relative accuracy parameter, a ranging direction absolute accuracy parameter, and a ranging distance relative accuracy parameter. The mobile telecommunications network apparatus of any one of the preceding claims, wherein the one or more accuracy parameters comprise a relative accuracy parameter, wherein the request to determine the location of the target communication device comprises a request to determine the location of the target communication device relative to a reference location, and wherein the location request message further comprises data indicating the reference location. A mobile telecommunications network apparatus including a first interface configured to provide communication with a mobile telecommunications network via a radio unit, and a second interface configured to provide direct device-to-device communication within a proximity range via the radio unit, the apparatus comprising: one or more processors configured to execute computer-readable instructions for implementing discovery of communication devices for device location determination, the instructions causing the one or more processors to: establish a direct device-to-device connection to a first communication device within the proximity range via the second interface; receive a positioning request message from the first communication device via the established connection, the positioning request message including a request to discover a second communication device within the proximity range; discover the second communication device in accordance with the received positioning request message; and transmit a positioning response message to the first communication device via the established connection indicating that the second communication device has been discovered. The mobile telecommunications network apparatus of claim 10, wherein the instructions further cause the one or more processors to: establish another direct device-to-device connection to the second communication device via the second interface; and perform location determination for the first or the second communication device in cooperation with the first and second communication devices, wherein performing the location determination comprises exchanging messages with the first and the second communication device via the direct device-to-device connections to the first and second communication device. The mobile telecommunications network apparatus of one of claims 10 or 11 , wherein the first communication device is a positioning server UE configured to determine the location of a target communication device, the target communication device being the second communication device. The mobile telecommunications network apparatus of one of claims 10 or 11 , wherein the second communication device is a positioning server UE configured to determine the location of a target communication device, the target communication device being the first communication device. The mobile telecommunications network apparatus of one of claims 12 or 13, wherein the instructions further cause the one or more processors to: receive an assistance data activation request message from the positioning server UE, the assistance data activation request message including a request to activate a transmission of assistance data by transmitting a positioning reference signal to the target communication device; select a configuration type for the positioning reference signal, the configuration type specifying properties of the positioning reference signal; and transmit the positioning reference signal in accordance with the selected configuration type to the target communication device, wherein the positioning reference signal is configured to enable the target communication device to perform measurements based on the positioning reference signal for enabling the positioning server UE to determine the location of the target communication device. The mobile telecommunications network apparatus of claim 13, wherein the instructions cause the one or more processors to: receive a location request message from the target communication device, the location request message comprising a request to determine the location of the target communication device and one or more accuracy parameters indicating a target accuracy for the location determination, wherein the one or more accuracy parameters comprise at least one of a relative accuracy parameter, an absolute accuracy parameter for a distance determination, and an absolute accuracy parameter for a direction determination; transmit the location request message to the positioning server UE to cause the positioning server UE to determine the location of the target communication device determined in accordance with the one or more accuracy parameters; receive a location response message from the positioning server UE, the location response message comprising data indicating the location of the target communication device; and transmit the location response message to the target communication device. A mobile telecommunications network apparatus including a first interface configured to provide communication with a mobile telecommunications network via a radio unit, and a second interface configured to provide direct device-to-device communication within a proximity range via the radio unit, the apparatus comprising: one or more processors configured to execute computer-readable instructions for assisting in determining a location of a target communication device, the instructions causing the one or more processors to: establish a direct device-to-device connection to a communication device within the proximity range via the second interface; and transmit an assistance data activation request message to the communication device via the established connection, the assistance data activation request message including a request to activate the transmission of assistance data by transmitting a positioning reference signal to the target communication device, wherein the assistance data activation request message is configured to cause the communication device to: select a configuration type for the positioning reference signal, the configuration type specifying properties of the positioning reference signal; and transmit the positioning reference signal in accordance with the selected configuration type to the target communication device via a direct device-to-device connection, wherein the positioning reference signal is configured to enable the target communication device to perform measurements based on the positioning reference signal for determining the location of the target communication device.

17. The mobile telecommunications network apparatus of claim 16, wherein the instructions further cause the one or more processors to receive an assistance data activation response message from the communication device via the established connection, the assistance data activation response message including the selected configuration type of the positioning reference signal.

18. The mobile telecommunications network apparatus of one of claims 16 or 17, wherein the instructions further cause the one or more processors to: receive a location request message from the communication device via the established connection, the location request message comprising a request to determine the location of the target communication device and one or more accuracy parameters indicating a target accuracy for the location determination, wherein the one or more accuracy parameters comprise at least one of a relative accuracy parameter, an absolute accuracy parameter for a distance determination, and an absolute accuracy parameter for a direction determination; determine the location of the target communication device in accordance with the one or more accuracy parameters; and transmit a location response message to the communication device via the established connection, the location response message comprising data indicating the location of the target communication device.

19. The mobile telecommunications network apparatus of any one of claims 16 to 18, wherein the apparatus is further configured to determine the location of the target communication device.

20. The mobile telecommunications network apparatus of any one of claims 16 to 19, wherein the apparatus is the target communication device, wherein the instructions further cause the one or more processors to: receive the target positioning reference signal from the communication device via the established connection in accordance with the selected configuration type, perform measurements based on the positioning reference signal for determining the location of the target communication device.