WO2023117057A1

WO2023117057A1 - Devices and methods for sidelink positioning in a mobile communication network

Info

Publication number: WO2023117057A1
Application number: PCT/EP2021/087023
Authority: WO
Inventors: Qi Wang; Xitao Gong; Richard Stirling-Gallacher
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2021-12-21
Filing date: 2021-12-21
Publication date: 2023-06-29

Abstract

A user equipment, UE, (130) for a mobile communication network (100) is disclosed. The UE (130) is configured to receive sidelink positioning discovery information from a network node (110, 120) of the mobile communication network (100), e.g. a radio access network, RAN, node (120) and/or a network entity implementing a location server (110) of the mobile communication network (100). The UE (130) is further configured to transmit a sidelink positioning discovery signal based on the sidelink positioning discovery information and/or receive a sidelink positioning discovery signal based on the sidelink positioning discovery information. Moreover, a correspondingly configured RAN node (120) and network entity implementing a location server (110) of the mobile communication network (100) are disclosed.

Description

DEVICES AND METHODS FOR POSITIONING IN A MOBILE COMMUNICATION

NETWORK

TECHNICAL FIELD

The present disclosure relates to mobile communication networks. More specifically, the present disclosure relates to devices and methods for positioning, i.e. determining a position of a UE in a mobile communication network.

BACKGROUND

Localization has been identified as one of the enabling technologies for next generation mobile communication networks. The radio access technology (RAT) dependent positioning techniques rely on the measurements obtained using reference signals transmitted in the downlink (DL) and/or uplink (UL), namely between a target device, such as a user equipment, UE, and one or multiple reference radio access network (RAN) nodes, e.g. base stations or transmit-receive points (TRPs). These measurements are collected either by a network entity implementing a location server, i.e. by the location management function (LMF) in the core network, or by the UEs. Based on the collected measurements, the position of the UEs can be determined.

However, according to a study carried out by 3GPP, given the stringent location requirements of commercial use cases, especially for industry verticals, conventional technologies have certain limits. For instance, as the distance between a UE and a reference RAN node increases, the DL/UL positioning measurement links may be lost or blocked by obstacles. This poses performance limits to localization given the RAN node deployment in terms of coverage and density.

SUMMARY

It is an objective of the present disclosure to provide improved devices and methods for positioning, i.e. determining a position of a UE in a mobile communication network.

The foregoing and other objectives are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures. According to a first aspect a user equipment, UE, for a mobile communication network is provided. The UE is configured to receive sidelink positioning discovery information from a network node of the mobile communication network. The network node may be a radio access network, RAN, node and/or a network entity implementing a location server of the mobile communication network, e.g. a location management function, LMF, in a core network, a local location management functionality in a RAN node or in a UE. The UE is further configured to transmit a sidelink positioning discovery signal based on the sidelink positioning discovery information and/or receive a sidelink positioning discovery signal based on the sidelink positioning discovery information. Thus, the UE according to the first aspect allows configuration of measurements over sidelink for improving the availability and accuracy of RAT dependent positioning in a mobile communication network.

As used herein “sidelink positioning discovery information” indicates the configuration of the sidelink positioning discovery signal transmitted or received by the UE. In further embodiments described below the location server may determine a transmit (TX) UE and/or a receive (RX) UE as well as their configuration for carrying out the sidelink positioning discovery based on a-priori location information and/or positioning measurements in the downlink and/or uplink. The location server may also configure the conditions or events that trigger a TX UE to transmit a sidelink discovery signal and a RX UE to receive this signal.

In a further possible implementation form, the UE is configured to discover a further UE based on the sidelink positioning discovery signal for performing sidelink positioning with the further UE. The UE may be configured to receive the sidelink positioning discovery information using the LTE Positioning Protocol (LPP).

In a further possible implementation form, the sidelink positioning discovery information comprises one or more of: time-frequency scheduling information of the sidelink positioning discovery signal, in particular, one or more resource pools for sidelink positioning discovery; one or more network identifiers, e.g. PLMN/SNPN identities, indicative of one or more networks for which the sidelink positioning discovery information applies; and geographical information indicative of one or more geographical regions for which the sidelink positioning discovery information applies. In a further possible implementation form, the UE is configured to transmit the sidelink positioning discovery signal based on the sidelink positioning discovery information and wherein the sidelink positioning discovery information comprises one or more of: information indicative of a transmission power for transmitting the sidelink positioning discovery signal; spatial direction information for transmitting the sidelink positioning discovery signal, such as an angle of departure, AoD, a beam index, an orientation and/or an antenna reference point index; and/or information indicative of one or more triggering conditions for triggering the transmission of the sidelink positioning discovery signal, such as threshold values for the positioning accuracy, uncertainty, measurement quality, receive signal power from network nodes, the number of network nodes which satisfy specified thresholds.

In a further possible implementation form, the UE is further configured to receive a sidelink positioning discovery measurement report request from the network node, e.g. the RAN node and/or the network entity implementing the location server, and to receive the sidelink positioning discovery signal via a sidelink, wherein the UE is configured to generate a sidelink positioning discovery measurement report based on the sidelink positioning discovery measurement report request and the sidelink positioning discovery signal.

In a further possible implementation form, the UE is configured to transmit the sidelink positioning discovery measurement report to the network node, e.g., a RAN node of the mobile communication network, and/or the network entity implementing the location server, and/or a further UE of the mobile communication network. The discovery measurement reports may be provided, for instance, to the LMF as location information using the LPP procedure. In case of the discovery measurement reports being provided to a specific UE, the sidelink discovery location information may be conveyed via the PC5 interface, i.e. using the PC5 signalling protocol.

In a further possible implementation form, the sidelink positioning discovery measurement report request comprises one or more of: information indicative of one or more measurements related to the sidelink positioning discovery signal, such as a RSRP, a receive signal strength indicator, a RX-TX time difference, a number of RSRPs and additional paths; information indicative of one or more measurements on a downlink and/or an uplink signal, such as RSRP or receive signal strength, indication of LoS/NLoS path availability; information indicative of one or more RAN node’s identities associated with the UE; information indicative of a reporting threshold for the sidelink positioning discovery measurement report in terms of a measurement quality indication; information indicative of a destination of the sidelink positioning discovery measurement report, namely either the location server or a specific UE indicated by an identity; and information about a number, a periodicity and/or a start time of the sidelink positioning discovery measurement report and one or more further sidelink positioning discovery measurement reports.

In a further possible implementation form, the sidelink positioning discovery signal comprises one or more of the following: a pre-defined physical signal associated with the UE; a data payload; and a reference signal for demodulation and measurements.

In a further possible implementation form, the data payload comprises a sidelink positioning discovery measurement request and/or scheduling information for transmitting the sidelink positioning discovery measurement report to a further UE of the mobile communication network and/or the location server.

In a further possible implementation form, the UE is further configured to transmit a sidelink positioning reference signal to a further UE for determining a position of the UE and/or the further UE. The UE may be further configured to receive a sidelink positioning reference signal from a further UE and to transmit information about the received sidelink positioning reference signal to the location server for determining a position of the UE.

In a further possible implementation form, the UE is further configured to receive a sidelink positioning reference signal from a further UE and to determine a position of the UE and/or the further UE based on the received sidelink positioning reference signal. According to a second aspect a method of operating a user equipment, UE, for a mobile communication network is provided. The method comprises the steps of: receiving sidelink positioning discovery information from a network node; transmitting a sidelink positioning discovery signal based on the sidelink positioning discovery information; and/or receiving a sidelink positioning discovery signal based on the sidelink positioning discovery information.

The method according to the second aspect of the present disclosure can be performed by the UE according to the first aspect of the present disclosure. Thus, further features of the method according to the second aspect of the present disclosure result directly from the functionality of the UE according to the first aspect of the present disclosure, as well as its different implementation forms described above and below.

According to a third aspect a radio access network, RAN, node for a mobile communication network is provided. The RAN node is configured to transmit a sidelink positioning discovery configuration to a network entity implementing a location server of the mobile communication network, e.g. location management function, LMF, in a core network, a local location management functionality in a RAN node or in a UE, wherein the “sidelink positioning discovery configuration” indicates one or more resources and/or configuration provided by the RAN node for transmission and/or reception of sidelink positioning discovery signals by one or more UEs of the mobile communication network. Thus, the RAN node according to the third aspect allows radio resource coordination among multiple RAN nodes for sidelink positioning discovery.

In a further possible implementation form, the sidelink positioning discovery configuration comprises one or more of: information about time-frequency allocation and/or a configuration of the sidelink positioning discovery signal, such as, one or more resource pools shared among multiple UEs for sidelink positioning discovery signal transmission; information about one or more carrier frequency indices or frequency band indicators with respect to the sidelink capability of the RAN node, the one or more UEs and/or a further UE receiving the sidelink positioning discovery signal; one or more network identifiers, e.g. PLMN/SNPN identities, indicative of one or more networks for which the sidelink positioning discovery configuration applies; and information indicating that one or more sidelink radio resources are intended for sidelink positioning discovery and/or sidelink positioning measurement.

In a further possible implementation form, the sidelink positioning discovery configuration comprise one or more configuration parameters and/or one or more indications indicative of one or more pre-defined configuration parameters.

In a further possible implementation form, the RAN node is configured to transmit a sidelink positioning discovery configuration to the network entity implementing the location server of the mobile communication network, e.g. LMF, in response to receiving a sidelink positioning discovery configuration request from the network entity implementing the location server.

In a further possible implementation form, the sidelink positioning discovery configuration request comprises one or more of: information about one or more parameters for generating the sidelink positioning discovery signal; an indication about a selected sidelink positioning discovery configuration of a plurality of pre-defined sidelink positioning discovery configurations; and information about an identity of the one or more UEs and/or an identity of a further UE transmitting and/or receiving the sidelink positioning discovery signal.

In a further possible implementation form, the RAN node is configured to: transmit sidelink positioning discovery information to the one or more UEs; and/or receive sidelink positioning discovery information from the network entity implementing the location server.

According to a fourth aspect a method of operating a radio access network, RAN, node for a mobile communication network is provided. The method comprises the step of: transmitting a sidelink positioning discovery configuration to a network entity implementing a location server of the mobile communication network, e.g. location management function, LMF, in a core network, a local location management functionality in a RAN node or in a UE, wherein the sidelink positioning discovery configuration indicates one or more resources and/or a configuration provided by the RAN node for transmission and/or reception of a sidelink positioning discovery signal by one or more UEs of the mobile communication network. The method according to the fourth aspect of the present disclosure can be performed by the RAN node according to the third aspect of the present disclosure. Thus, further features of the method according to the fourth aspect of the present disclosure result directly from the functionality of the RAN node according to the third aspect of the present disclosure, as well as its different implementation forms described above and below.

According to a fifth aspect a network entity of a mobile communication network is provided, wherein the network entity is configured to implement a location server of the mobile communication network, e.g. location management function, LMF, in a core network, a local location management functionality in a RAN node or in a UE. The location server is configured to receive a sidelink positioning discovery configuration from one or more RAN nodes of the mobile communication network, wherein the sidelink positioning discovery configuration indicates one or more resources and/or a configuration provided by the one or more RAN nodes for transmission and/or reception of a sidelink positioning discovery signal by an UE of the mobile communication network. The location server is further configured to transmit sidelink positioning discovery information based on the sidelink positioning discovery configuration to one or more UEs of the mobile communication network. Thus, the network entity implementing the location server according to the fifth aspect allows efficient provision of coordinated radio resource and parameter configurations of the sidelink positioning discovery signal to the UEs in a mobile communication network.

In a further possible implementation form, the location server is configured to generate the sidelink positioning discovery information based on the sidelink positioning discovery configuration.

In a further possible implementation form, the location server is further configured to transmit a sidelink positioning discovery configuration request to at least one RAN node of the mobile communication network and to receive a sidelink positioning discovery configuration in response to the sidelink positioning discovery configuration request for transmitting and/or receiving a sidelink positioning discovery signal by one or more UEs via a sidelink of the mobile communication network.

In a further possible implementation form, the sidelink positioning discovery configuration request comprises one or more of: one or more parameter configurations for generating the sidelink positioning discovery signal; an indication about a selected sidelink positioning discovery configuration of a plurality of pre-defined sidelink positioning discovery configurations; and information about an identity of one or more UEs.

In a further possible implementation form, the location server is further configured to transmit the sidelink positioning discovery configuration request, in response to one or more of: a request from the one or more UEs; a request from a further entity; an insufficient positioning accuracy of the one or more UEs; and an insufficient measurement quality on a downlink and/or an uplink of the one or more UEs, such as a reference signal receiver power (RSRP), number of Line-of-Sight (LoS)/Non-Line-of_Sight (NLoS) paths, spatial direction information (Angle of Departure (AoD), Angle of Arrival (AoA), beam index), power consumption.

In a further possible implementation form, the sidelink positioning discovery information comprises one or more of: information about time-frequency allocation and/or a configuration of the sidelink positioning discovery signal, such as, one or more resource pools shared among multiple UEs for sidelink positioning discovery signal transmission; information about one or more carrier frequency indices or frequency band indicators with respect to the sidelink capability of the RAN node, the one or more UEs and/or a further UE; one or more network identifiers, e.g. PLMN/SNPN identities, indicative of one or more networks for which the sidelink positioning discovery information applies; and information indicating that the one or more sidelink radio resources are intended for sidelink positioning discovery and/or sidelink positioning measurement.

In a further possible implementation form, the sidelink positioning discovery information comprises one or more of: information indicative of a transmission power for transmitting the sidelink positioning discovery signal by the one or more UEs; spatial direction information for transmitting the sidelink positioning discovery signal by the one or more UEs, such as an angle of departure, AoD, a beam index, an orientation and/or an antenna reference point index; and/or information indicative of one or more triggering conditions for triggering the transmission of the sidelink positioning discovery signal, such as threshold values for the positioning accuracy, uncertainty, measurement quality, receive signal power from network nodes, the number of network nodes which satisfy specified thresholds.

In a further possible implementation form, the location server is configured to transmit a sidelink positioning discovery measurement report request to one or more UEs and/or and to receive, in response, a respective sidelink positioning discovery measurement report from one or more UEs based on the sidelink positioning discovery measurement report request.

In a further possible implementation form, the location server is configured to determine the UE for transmitting a sidelink positioning reference signal to a further UE and/or receiving a sidelink positioning reference signal from a further UE for determining a position of the UE and/or the further UE.

According to a sixth aspect a method of operating a network entity of a mobile communication network is provided, wherein the network entity is configured to implement a location server of the mobile communication network, e.g. location management function, LMF, in a core network, a local location management functionality in a RAN node or in a UE. The method comprises the steps of: receiving a sidelink positioning discovery configuration from one or more RAN nodes of the mobile communication network, wherein the sidelink positioning discovery configuration indicates one or more resources and/or a configuration provided by the one or more RAN nodes for transmission and/or reception of a sidelink positioning discovery signal by one or more UEs of the mobile communication network; and transmitting sidelink positioning discovery information based on the sidelink positioning discovery configuration to one or more UEs of the mobile communication network.

The method according to the sixth aspect of the present disclosure can be performed by the network entity implementing the location server according to the fifth aspect of the present disclosure. Thus, further features of the method according to the sixth aspect of the present disclosure result directly from the functionality of the network entity implementing the location server according to the fifth aspect of the present disclosure, as well as its different implementation forms described above and below.

According to a seventh aspect, a computer program product is provided, comprising a computer-readable storage medium for storing program code which causes a computer or a processor to perform the method according to the second aspect, the method according to the fourth aspect or the method according to the sixth aspect, when the program code is executed by the computer or the processor.

Details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments of the present disclosure are described in more detail with reference to the attached figures and drawings, in which:

Fig. 1 shows a schematic diagram illustrating a mobile communication network, including a plurality of UEs according to an embodiment, a plurality of RAN nodes according to an embodiment and a network entity implementing a location server according to an embodiment;

Fig. 2 shows a signalling diagram illustrating a sidelink positioning discovery procedure according to an embodiment;

Fig. 3 shows a signalling diagram illustrating a procedure for obtaining sidelink positioning discovery configuration according to an embodiment;

Fig. 4 shows a signalling diagram illustrating a procedure for providing sidelink positioning discovery information using LLP according to an embodiment;

Fig. 5 shows a signalling diagram illustrating a procedure for providing sidelink positioning discovery information using system information block, SIB, according to an embodiment; Fig. 6 shows a signalling diagram illustrating a procedure for requesting and reporting sidelink positioning discovery measurements according to an embodiment;

Fig. 7 shows a schematic diagram illustrating a mobile communication network, including a plurality of RAN nodes according to an embodiment and a network entity implementing a location server according to an embodiment;

Fig. 8 shows a signalling diagram illustrating a procedure for configuring predefined resource pools for sidelink positioning discovery according to an embodiment for the mobile communication network of figure 7;

Fig. 9 shows a schematic diagram illustrating a mobile communication network, including a plurality of RAN nodes according to an embodiment and a network entity implementing a location server according to an embodiment;

Fig. 10 shows a signalling diagram illustrating a procedure for dynamic allocation of resource pools for sidelink positioning discovery according to an embodiment for the mobile communication network of figure 9;

Fig. 11 shows a signalling diagram illustrating a procedure for enhancing network-based positioning with inter-UE sidelink positioning cooperation discovery according to an embodiment;

Fig. 12 shows a schematic diagram illustrating a mobile communication network, including a plurality of UEs in the form of vehicles and a plurality of RAN nodes according to an embodiment;

Fig. 13 shows a signalling diagram illustrating a procedure for enhancing UE-based positioning with inter-UE sidelink positioning cooperation discovery according to an embodiment;

Fig. 14 shows a flow diagram illustrating a method of operating a UE according to an embodiment;

Fig. 15 shows a flow diagram illustrating a method of operating a RAN node according to an embodiment; and Fig. 16 shows a flow diagram illustrating a method of operating a network entity implementing a location server according to an embodiment.

In the following, identical reference signs refer to identical or at least functionally equivalent features.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following description, reference is made to the accompanying figures, which form part of the disclosure, and which show, by way of illustration, specific aspects of embodiments of the present disclosure or specific aspects in which embodiments of the present disclosure may be used. It is understood that embodiments of the present disclosure may be used in other aspects and comprise structural or logical changes not depicted in the figures. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

For instance, it is to be understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if one or a plurality of specific method steps are described, a corresponding device may include one or a plurality of units, e.g. functional units, to perform the described one or plurality of method steps (e.g. one unit performing the one or plurality of steps, or a plurality of units each performing one or more of the plurality of steps), even if such one or more units are not explicitly described or illustrated in the figures. On the other hand, for example, if a specific apparatus is described based on one or a plurality of units, e.g. functional units, a corresponding method may include one step to perform the functionality of the one or plurality of units (e.g. one step performing the functionality of the one or plurality of units, or a plurality of steps each performing the functionality of one or more of the plurality of units), even if such one or plurality of steps are not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary embodiments and/or aspects described herein may be combined with each other, unless specifically noted otherwise.

Figure 1 shows a schematic diagram illustrating an exemplary scenario for RAT dependent positioning in a mobile communication network 100, including a plurality of UEs 130 according to an embodiment, a plurality of RAN or network nodes 120 according to an embodiment and a network entity implementing a location server 110 according to an embodiment. In an embodiment, the location server may provide a location management function (LMF). The RAN or network nodes 120 with precisely known location are utilized as the positioning references. In the exemplary scenario shown in figure 1 , for the target “UE 1 ” 130, only one link to the “network node 1 ” 120 can be utilized for positioning measurements. The Line-of-Sight links to the other network nodes 120 are either blocked (e.g. “network node 2 “) or with insufficient reception (e.g. “network node 3 and 4”). In order to achieve the required Location Service (LCS) Quality of Service (QoS), e.g. accuracy and/or latency, embodiments disclosed herein allow a cooperation among the plurality of UEs by establishing sidelink measurement links to neighboring UEs 130 and jointly inferring the position(s) thereof. Although every additional cooperating UE 130 provides additional location information in theory, the measurement and communication among UEs 130 consumes resource in terms of time, spectrum, energy and computational power. Hence, embodiments disclosed herein allow discovering the highly informative UEs 130 with which to proceed with sidelink positioning measurements and to achieve LCS QoS while efficiently utilizing the communication resources in the mobile communication network 100.

Thus, embodiments disclosed herein provide a procedure for the discovery of sidelink positioning measurement links. For the example shown in figure 1 , embodiments disclosed herein allow discovering the measurement link between UE 1 and UE 2 and that between UE 1 and UE 3 (instead of the others), since they provide interconnection of multiple network reference nodes 120. More specifically for positioning of the target UE 1 , UE 2 and UE 3 provides location information associated with the network nodes 2, 3 and 4 which were not reachable by the UE 1 , leading to potential performance improvement.

The determination of cooperating UEs implemented by embodiments disclosed herein may be based on three aspects, namely, network geometry including the location information of the reference RAN nodes 120 and the UEs 130, measurements between the reference RAN nodes 120 and the UEs 130, and measurements between the UEs 130. For RAT-dependent positioning, the former two may be obtained at the location server, i.e. location management function (LMF) 110, in the network 100 or at the UE 130 using conventional methods. Embodiments disclosed herein provide a sidelink positioning discovery procedure for obtaining inter-UE measurements at the location server 110 or at the UE 130. A centralized network function, e.g. the LMF 110, may coordinate the radio resources for the inter-UE sidelink positioning discovery so that cooperative positioning of the UEs 130 may be enabled efficiently.

In an embodiment, the sidelink positioning discovery procedure may comprise the four main stages shown in figure 2. A first main stage 201 is referred to as "Obtain sidelink positioning discovery configuration" in figure 2. The general goal of the sidelink positioning discovery is to discover neighboring UEs 130 which may provide location information associated with different reference RAN nodes 120, e.g. gNBs, TRPs. Therefore, in an embodiment, radio resource coordination among multiple RAN nodes of the cellular network 100 may be performed. The network entity implementing a loction server, e.g. the LMF 110, may obtain the radio resource for sidelink positioning discovery. This resource may be either dedicated to a specific UE 130 or shared among multiple UEs 130. The resource may be either dedicated for sidelink positioning discovery or shared for both sidelink positioning discovery and measurements. This prerequisite stage may be triggered by the location server 110 due to one or more of the following events: the required quality of service (QoS) of the location service (LCS) of one or a group of UEs 130 is not achieved; a measurement quality or report on the downlink and/or uplink is insufficient (such as reference signal receiver power (RSRP), the number of Line-of-Sight (LoS)/Non-Line-of_Sight (NLoS) paths, spatial direction information (Angle of Departure (AoD), Angle of Arrival (AoA), beam index), power consumption); and/or a request by one or more of the plurality of UEs 130 for positioning enhancement, i.e. obtaining more detailed information about the UE's position. For the UE-based positioning another trigger may be a LCS service request from an application running on the respective UE or external clients, which triggers sidelink positioning, e.g. a relative positioning. The further stages of the sidelink positioning discovery procedure illustrated in figure 2 will be described in more detail further below.

Figure 3 shows steps of a protocol (herein referred to as "New Radio Positioning Protocol A (NRPPa)") implemented by embodiments disclosed herein for sidelink positioning discovery configuration transfer. In a protocol step 301 the LMF 110 may initiate the procedure by sending a sidelink positioning discovery configuration request to a specific RAN node 120. The request message may consist of an explicit parameter configuration of the sidelink positioning discovery signal or an activation of one or more pre-defined sidelink positioning discovery configurations at the RAN node 120. The request may also comprise the identities of the UEs 130 of interest. In a further protocol step 303, based on the request received in protocol step 301 , the RAN node 120 provides the response to the LMF 110. In an embodiment, this response message may include information about a time-frequency allocation and/or sidelink positioning discovery signal configuration of one or more of the plurality of UEs 130, in particular information about one or multiple resource pools shared among multiple UEs 130 for sidelink positioning discovery signal transmission (the resource pool configuration may include parameters such as time-frequency scheduling information, power control parameters and the like).

In an embodiment, the response message sent by the RAN node 120 to the LMF 110 in the protocol step 303 may include carrier frequency indices or frequency band indicators with respect to the sidelink capability of the RAN node 120 and/or the UEs 130 (priority indicators if multiple bands are supported). It may be indicated that unlicensed band should be used for sidelink positioning discovery.

In an embodiment, the response message sent by the RAN node 120 to the LMF 110 in the protocol step 303 may include a PLMN identity, a SNPN identity and/or network identifier, indicating one or more networks, e.g. the network 100, for which the sidelink positioning discovery information is valid. If in the protocol step 301 the LMF 100 requests the RAN node 120 to activate one or more pre-defined sidelink positioning discovery configurations, a confirmation may be sent by the RAN node 120 to the LMF 110.

In an embodiment, the response message sent by the RAN node 120 to the LMF 110 in the protocol step 303 may further include an indication that the resource is for sidelink positioning discovery and/or sidelink positioning measurement.

In a further protocol step 301 the LMF 110 may request a sidelink positioning discovery configuration update from a respective RAN node 120. The message may include the parameters to be updated and/or the periodicity of such an update. The updated sidelink positioning discovery configuration is provided to the LMF 110 in the protocol step 305.

The protocol illustrated in figure 3 and implemented by devices according to an embodiment allows a centralized network entity implementing the location server 110, e.g. the LMF in the core network, to obtain information about the radio resource configuration from multiple RAN nodes 120 and further coordinate the radio resource for sidelink positioning discovery procedure within the coverage of multiple RAN nodes 120. Moreover, the protocol illustrated in figure 3 and implemented by devices according to an embodiment may facilitate sidelink positioning measurements among UEs 130 at the edge of or in areas of overlapping cells.

A second stage 202 of figure 2, where the sidelink positioning discovery procedure is configured, will be described in the following under further reference to figures 4 and 5. In an embodiment, the LMF 110 may determine the transmit (TX) UE 130a and/or the receive (RX) UE 130b as well as their configuration for carrying out the sidelink positioning discovery based on a-priori location information and/or positioning measurements in the downlink and/or uplink. The LMF 110 may also configure the conditions or events that trigger the TX UE 130a to transmit a sidelink positioning discovery signal and the RX UE to receive. The configuration, in particular, of the radio resource, provided to the UEs 130a,b by the LMF 110 is not necessarily the same as described in the context of figure 3. This configuration may be transferred to the corresponding UEs 130 as positioning assistance data using LTE Positioning Protocol (LPP) procedures, as shown in a step 401 of figure 4. The data transmitted in step 401 of figure 4 may comprise sidelink positioning discovery information

The sidelink positioning discovery information may comprise the following information: time-frequency scheduling information of the sidelink positioning discovery signal, in particular, resource pools for sidelink positioning discovery; PLMN/SNPN identities and/or other network identifier(s) indicating the scope that the sidelink positioning discovery information applies (the presence of these identities or identifiers may also imply that the UE 130 has been authorized to carry out the sidelink positioning discovery procedure within the identified PLMN/SNPN); one or more identifiers of geographical information, e.g. a geographical region, where the sidelink positioning discovery information applies; and/or triggering conditions or events of the sidelink positioning discovery signal transmission or reception, e.g. thresholds of positioning accuracy, uncertainty, measurement quality, receive signal power from reference RAN nodes 120, the number of reference RAN nodes 120 which satisfy specified thresholds.

Specifically for the TX UE 130a the sidelink positioning discovery information may comprise one or more of the following: a transmit power with respect to the determined discovery range as illustrated in figure 1 ; and/or spatial direction information, e.g. angular information in global or local coordinates, beam index, orientation and antenna reference point index, and the like, which reflects the geometry of the desired reference nodes. For instance, for the example shown in figure 1 , UE 1 may transmit a sidelink positioning discovery signal using different antenna panels than for receiving from network node 1 , in order to explore the environment using the sidelink channel. UE 2 may be configured to detect sidelink positioning discovery signal using different antenna panels than for receiving from network node 3 and 4. location information obtained by the RX UE 130b.

Optionally in case of sidelink positioning discovery information which are not associated to a specific UE 130, e.g. shared time frequency resources among multiple UEs 130, resource pool and triggering conditions, a System Information Block (SIB) may be used for transfer of sidelink positioning discovery information, as illustrated in step 501 of figure 5. The sidelink positioning discovery information is provided to a RAN node 120 by the LMF 110, then broadcasted as SIB to the UEs 130.

The steps illustrated in figures 4 and 5 allow a centralized network entity, e.g. location server 110, the LMF, to provide the sidelink positioning discovery information to the UEs according to location service’s requirements and optimize resource consumption while achieving the LCS QoS. It requires least functionality to be added on the UE side, while offers potential enhancement for network-based positioning schemes. For the case of UE- based positioning, a UE 130 may also start to transmit or receive a sidelink positioning discovery signal autonomously according to the pre-configuration provided in the sidelink positioning discovery information.

A further stage 203 of the sidelink discovery procedure of figure 2 for providing a discovery measurement report is illustrated in figure 6. The LMF 110 may request the RX UE(s) 130b to measure the sidelink positioning discovery signal and to provide the discovery measurement report (step 601 of figure 6). As illustrated by steps 603a and 603b of figure 6, the measurement report may be transferred either to the LMF 110a as location information using the LPP procedure, or to the TX UE 130a over the PC5 interface.

In an embodiment, the request for the sidelink positioning discovery measurement report of step 601 may comprise information about requested measurements on the sidelink positioning discovery signal, e.g. RSRP, receive signal strength indicator, RX-TX time difference, number of RSRPs and additional paths. In an embodiment, the request for the sidelink positioning discovery measurement report of step 601 may comprise information about requested measurements on the downlink and/or uplink, e.g. RSRP or receive signal strength, reference RAN nodes’ identities, indication of LoS/NLoS path availability. In an embodiment, the request for the sidelink positioning discovery measurement report of step 601 may further comprise information about a reporting threshold in terms of measurement quality indication; information about a reporting destination, namely either the LMF 110 or a specific UE 130a indicated by an identity; and/or information about the number, periodicity, and/or start time of the discovery measurement reports.

As already mentioned above, the sidelink discovery measurement reports may be provided to the LMF 110 as location information using the standard LPP procedure (including the sidelink positioning discovery measurement reports) or to a specific UE 130 using the PC5 interface and PC5 signaling protocol. The reporting destination UE 130 may be the TX UE 130a (as shown in figure 6) or another UE 130.

The protocol illustrated in figure 6 allows a centralized network entity implementing the location server 110, e.g. the LMF, to enable cooperating UE determination in the network 100 at the LMF 110 or at a specific UE 130, such as the TX UE 130a. The LMF 110 may control the reporting overhead by adjusting the configuration. It also facilitates UE-based positioning, where a UE 130 obtains sidelink positioning discovery measurements using a pre-configured setting provided or indicated by the network.

For the sidelink positioning discovery stage 204 of figure 2 the TX UE 130a transmits a sidelink positioning discovery signal based on the sidelink positioning discovery information received. The sidelink positioning discovery signal may be transmitted periodically or semi-persistently. It may consist of at least one of the following: a predefined physical signal associated with a specific UE identity, a data payload, and/or a reference signal for demodulation and measurements. The data payload may contain the requested location information or assistance data as well as the scheduling information for the measurement reporting over the sidelink, according to which the RX UE(s) 130b sends the measurement report(s) to a specific UE 130 over the PC5 interface. As a result of the sidelink positioning discovery stage 204 of figure 2 either the location server 110 in a stage 205a of figure 2 or the TX UE 130a and/or the RX UE(s) 130b in a stage 205b of figure 2 may select the direct link to configure the sidelink positioning reference signal.

Thus, based on the sidelink positioning discovery information, sidelink positioning discovery signals are only transmitted by the selected TX UE 130a when needed. Moreover, this type of discovery signal may consume less communication resources than typical positioning reference signals for obtaining positioning measurements. This is because the discovery signal may serve as a sounding process to discover neighboring UEs 130 which may provide additional location information. Based on the initial measurements of the sidelink positioning discovery signal, the location server 110, e.g. LMF in the network or a specific UE 130 may determine which link to be considered for sidelink positioning measurements and/or which link to be used for which positioning measurements.

Thus, embodiments disclosed herein allow a sidelink positioning discovery procedure based on the a-priori information obtained at the location server 110, e.g. LMF. This allows a UE 130 to explore the environment for additional location information using one or more sidelink links under the guidance of the location server. It complements the RAT- dependent positioning using downlink and/or uplink measurements and may improve positioning availability with low overhead. This network-assisted sidelink positioning discovery procedure further enables centralized inter-UE cooperation optimization at the centralized network entity implementing the location server 110, e.g. the LMF or at a location management functionality in a RAN node or a specific UE 130.

Figure 7 shows a further embodiment with the location server 110 coordinating sidelink positioning discovery using pre-configured resources. In this embodiment a RAN node 120 may provide the pre-defined radio resource configuration for sidelink positioning discovery. This may be indicated using a parameter in the capability information of the RAN node 120. The pre-defined radio resource may be obtained, activated and/or configured by the location server 110. In the exemplary embodiment shown in figure 7 each of three exemplary RAN nodes 120 in the form of a first gNB 1 , a second gNB 2 and a third gNB 3 may be pre-configured with a number of resource pools which can be used for sidelink positioning discovery. The location server 110 may obtain these preconfigured resource pools and activate them for either transmission or reception of a sidelink discovery signal. This allows a UE 130 transmitting a sidelink positioning discovery signal in the coverage of one RAN node to be monitored by the RX UE(s) 130b in the coverage of the other RAN nodes.

Figure 8 shows the corresponding signaling diagram for the embodiment shown in figure 7 using NRPPa. In a first step 801 the LMF 110 obtains the respective pre-defined resource pool for sidelink positioning discovery from the three gNBs 120 using sidelink positioning discovery configuration request described above. In Step 2, the three gNBs 120 provide the sidelink positioning discovery configuration response to the LMF 110, which contains the resource pool pre-defined by each gNB 120. Based on the requirements of sidelink positioning discovery and the coarse location information of the involved UEs 130, the LMF 110 may activate the sidelink positioning discovery resource pool 1 at gNB 1 as transmit pool and the pool 4 at gNB 2 and the pool 7 at gNB 3 as receive pool. The activation may be included as parameters in the sidelink discovery configuration requests, as shown in a respective third step 805 for the three gNBs 120. In a respective fourth step 807 the requested configurations may be confirmed or rejected by the involved gNBs 120

Figure 9 shows a further embodiment with the location server 110 coordinating sidelink positioning discovery using dynamically allocated resources. In this embodiment a common resource allocation from multiple gNBs 120 for sidelink positioning discovery may be obtained. For instance, the LMF 110 may request a TX resource pool allocation X from a gNB 1 for sidelink positioning discovery and then requests the other involved gNBs 120, i.e. gNB 2 and gNB 3 in the exemplary embodiment of figure 9, to set the pool X as the TX and/or RX resource pools for sidelink positioning discovery.

Figure 10 shows the corresponding signaling diagram for the embodiment shown in figure 9 using NRPPa. In a first step 1001 the LMF 100 sends a sidelink positioning discovery configuration request (referred to as NRPPa message) to the gNB 1 120, requesting for a TX resource pool for sidelink positioning discovery. The LMF 110 may request to the RAN node that a TX UE attached to if the TX UE has been determined. In a second step 1003, the gNB 1 provides a response with the resource configuration for sidelink positioning discovery, e.g. SLpos_discRP_X. In respective third steps 1005a and 1005b, the LMF 100 sends sidelink positioning discovery configuration request included inNRPPa messages to the gNB 2 and gNB3, requesting to configure the SLpos_discRP_X as receive pool. The configuration of SLpos_discRP_X is included in the sidelink positioning discovery configuration request, i.e. the NRPPa message. In a respective fourth step 1007a and 1007b the requested configuration is acknowledged or rejected by the respective gNB 120.

In the conventional network-based positioning scheme, a location server, i.e. LMF, configures the positioning reference signals in the downlink and/or uplink, obtains measurement reports and determines the respective position of the target UEs. By means of the sidelink positioning discovery procedure implemented by embodiments disclosed herein, the location server 110 according to an embodiment may determine to trigger inter-UE positioning cooperation in case that localization performance enhancement is needed. A procedure according to an exemplary embodiment is shown in figure 11 and described in the following.

The LMF may carry out the conventional network-based positioning procedure using only the positioning measurements in the downlink and/or uplink. The required LCS QoS may not be achieved due to insufficient number of reference nodes 120, limited positioning measurement quality, e.g. RSRP, number of LoS/NLoS paths, angular information (AoA, AoD, beam index) and/or power consumption. Based on the positioning measurements obtained over downlink and/or uplink, the estimated location information of the involving UEs 130 as well as the causes for the positioning error causes, the LMF 110 may determine which UE 130 to send a sidelink positioning discovery signal (e.g. “UE 1” 130 in the example of figure 1) and which UEs are configured to monitor (e.g. “UE 2, 3, 4, 5” 130 in the example of figure 1). At this stage, neither the UEs 130 nor the LMF 110 may have decided which and how the inter-UE links are to be utilized for positioning, namely, which positioning reference signals to be configured between which UEs 130 for cooperative positioning.

In a first step 1101 of figure 11 the LMF 110 obtains radio resource by sending a sidelink positioning discovery configuration request message to the RAN node 120 that serves UE 1 , UE 2 and UE 3 and receives the response correspondingly (step 1103). This makes sure that the UEs 130 in the inter-sector area may communicate with each other using the coordinated radio resource. The obtained radio resource configuration may be allocated for the specific UEs 130 indicated by the LMF, e.g. time-frequency allocation, start time, duration of transmission as well as transmit power indicators. This applies to the licensed band where radio resources can be schedule by the RAN nodes 120. The obtained response message may also contain non-UE associated configuration of the sidelink positioning discovery signal, e.g. frequency band index, channel index, resource pool and/or number of transmissions, and the like. Based on the radio access capability of the involved UEs 130, the RAN node 120 may recommend the LMF 110 to configure the sidelink positioning discovery to be carried out in the unlicensed band.

In a further step 1105 the LMF 110 determines the TX UE(s) 130 and the RX UE(s) 130 among the plurality of UEs 130 and provides sidelink positioning discovery information as positioning assistance data using LPP as described above. Specifically for the TX UE(s) 130a (e.g. UE 1), the sidelink positioning discovery information may include transmit power related configurations corresponding to the desired discovery range, spatial direction information, such as angle, beam index, antenna index which aims to discover UEs 130 in the complement direction of the network node 1 with downlink measurements. If the neighbor UEs has been discovered in the proximity of the TX UE by the network 100, the neighbor UEs’ identities may be provided to the TX UE. The LMF 110 may only configure the latest start time, number of transmissions and/or TX power information without providing specific scheduling information. The UEs 130 may carry out the sidelink positioning discovery procedure using a shared spectrum, i.e. unlicensed band.

Optionally, in a further step 1107 of figure 11 , the sidelink positioning discovery information may be conveyed to the RAN nodes 120 by the LMF 110 and broadcasted as on-demand System Information Block (SIB). Examples include time-frequency allocation, e.g. resource pools, frequency band indicator, channel index, start time/slot number, periodicity, and number of repetition. This allocated time-frequency resource, e.g. resource pool, may be dedicated for sidelink positioning discovery or shared with transmission of other signals such as sidelink positioning measurements or sidelink communication. This may be indicated as well.

In a further step 1109 of figure 11 the LMF 110 configures the RX UEs 130b to detect and provide measurement reports of the sidelink positioning discovery signal to the LMF 110, e.g. RSRPs, reference signal index, antenna or beam indicator, additional path information in case that LoS/NLoS information is desired. Conditions or thresholds may be applied for reporting.

In a further step 1111 the TX UE 130a transmits a sidelink positioning discovery signal as configured. The RX UE(s) 130b measure the sidelink positioning discovery signal according to the received configuration and report the measurements to the LMF via LPP signaling (step 1113 of figure 11). Based on the inter-UE measurements, downlink and/or uplink measurements and location information of the RAN nodes 120 and the UEs 130, the LMF determines whether and how to configure the reference signal for positioning measurements between the UE 130a and the UE 130b (step 1115 of figure 11).

The sidelink positioning discovery procedure shown in figure 11 allows improving positioning availability with manageable sidelink measurement overhead. Given the scenario illustrated in Figure 1 , UE 1 cannot be localized using trilateration based positioning methods. With the cooperating UEs discovered by means of the embodiments disclosed herein, inter-UE positioning measurements between UE 1 and UE 2, UE 1 and UE 3 may be configured according to the LCS QoS requirements. A centralized inter-UE cooperation optimization scheme may be implemented at the location server 110, so that no additional computational capability is required at the participating UEs 130 for cooperative positioning.

For RAT-dependent UE-based positioning defined in 3GPP [TS38.305], a UE obtains reference signal configuration, positioning measurements and location information of the reference nodes and calculates its own position. According to embodiments disclosed herein, in order to enable inter-UE cooperation positioning over the sidelink, a UE 130 according to an embodiment may request the location served 10 according to an embodiment for a (pre-)configuration of sidelink positioning discovery. This may be triggered by the UE 130 based on its own capability and/or insufficient positioning information obtained from downlink and/or uplink. Figure 12 shows a corresponding exemplary embodiment, where inter-vehicle cooperation discovery is configured for UE- based positioning. As shown in figure 12, three vehicles, i.e. UEs 130 drive on the street from the coverage of RAN node A towards RAN node B. Inter-vehicle links may be discovered by embodiments disclosed herein to complement the positioning measurements over the downlink given the measurement quality degradation on the sector edge. Although which measurements to consider for positioning calculation may be determined by each individual UE 130, the radio resource and/or the LCS QoS may be managed by the network. After UE 1 carried out the sidelink positioning discovery, it may determine to cooperate with UE 2 instead of all those that can be heard in its vicinity. A corresponding procedure according to an exemplary embodiment is shown in figure 13 and described in the following.

In a first step 1301 of figure 13 the UE 130a requests positioning assistance data containing sidelink positioning discovery information from the LMF 110. The UE 130a may obtain this configuration and store it as pre-configuration and/or have it updated periodically.

In case that the radio resource configuration is not available at the LMF 110, the LMF sends a sidelink positioning discovery configuration request to the RAN node 120 and obtains the sidelink positioning discovery configuration (steps 1303 and 1305 of figure 13). The obtained radio resource configuration may be allocated for the specific UEs 130 indicated by the LMF 110, e.g. time-frequency allocation, start time, duration/number of transmission as well as transmit power indicators. This applies to the licensed band where radio resources can be scheduled by the RAN node(s) 120. The obtained response message may also contain a non-UE associated configuration of the sidelink positioning discovery signal, e.g. frequency band index, channel index, resource pool, maximum transmit power and/or number of transmissions etc. Based on the radio access capability of the involved UEs 130, the RAN node(s) 120 may recommend the LMF 110 to configure sidelink positioning discovery to be carried out in the unlicensed band.

In a further step 1307 the LMF 110 provides positioning assistance data containing the sidelink positioning discovery information. The sidelink positioning discovery information may include the parameters already described above. In order to enable sidelink positioning discovery procedure autonomously triggered at a UE 130 while minimizing the required resources, the triggering thresholds or events may be configured by the LMF 110. It may include, for instance, an instantaneous positioning error, or measurement quality on the downlink and/or uplink, motion change, number of network nodes detected, timer expiry and the like. For instance, the UE 1 in the example shown in figure 11 may trigger sidelink positioning discovery signal transmission using the front antenna in the driving direction while degraded reception of the network node 1 is observed.

In an optional further step 1309 the common information of sidelink positioning discovery information can be broadcasted using SIB. This information may apply to a specific zone or geographical area where inter-UE cooperation is supported.

In a further step 1311 of figure 13 the LMF 110 may configure the RX UEs 130b to monitor the sidelink positioning discovery signal and to provide measurement reports as well as its location information under certain conditions. This report may be sent to the TX UE 130a over the PC5 interface in case that the cooperation between the UEs 130 is determined at the TX UE 130a. Otherwise, based on the obtained measurements, the RX UE 130b may determine how or whether to further exploit the direct link for positioning measurement.

As shown in figure 13, steps 1301 to 1311 may be carried out prior to the actual positioning process as pre-configuration. Thus, it may be utilized for UEs 130 in the partial or out-of-coverage scenarios or as enhancement of UE-based positioning. In a further step 1313 the TX UE 130a transmits a sidelink positioning discovery signal based on the received configuration, i.e. triggered by a pre-configured event. In case that the measurement report is required at the TX UE 130a, the RX UE 130b may provide it to the TX UE 130a using the PC5 interface (step 1315). Based on the measurement report received from the responding UEs 130b, the TX UE 130a determines whether to obtain positioning reference signal for this direct link (step 1317). The embodiment shown in figure 13 illustrates that the sidelink positioning discovery information may be introduced as pre-configuration, enabling UE autonomous sidelink positioning discovery. By careful design of the triggering condition(s) depending on the specific application scenario, it is possible to avoid flooding the sidelink transmission resources with unnecessary positioning measurements.

Figure 14 shows a flow diagram illustrating a method 1400 for operating a UE 130 according to an embodiment. The method 1400 comprises a step 1401 of receiving sidelink positioning discovery information from a network node, e.g. a network entity implementing a location server 110 or a RAN node 120. The method further comprises a step 1403a of transmitting a sidelink positioning discovery signal based on the sidelink positioning discovery information. Alternatively or additionally, the method further comprises a step 1403b of receiving a sidelink positioning discovery signal based on the sidelink positioning discovery information.

The method 1400 can be performed by each of the plurality of UEs 130 according to an embodiment. Thus, further features of the method 1400 result directly from the functionality of an UE 130 as well as the different embodiments thereof described above and below.

Figure 15 shows a flow diagram illustrating a method 1500 for operating a RAN node 120 according to an embodiment. The method 1500 comprises a step 1501 of transmitting a sidelink positioning discovery configuration to a network entity implementing the location server 110 of the mobile communication network 100, wherein the sidelink positioning discovery configuration indicates one or more resources and/or a configuration provided by the RAN node 120 for transmission and/or reception of a sidelink positioning discovery signal by one or more of the plurality of UEs 130 of the mobile communication network 100. The method 1500 can be performed by each of the plurality of RAN nodes 120 according to an embodiment. Thus, further features of the method 1500 result directly from the functionality of a RAN node 120 as well as the different embodiments thereof described above and below.

Figure 16 shows a flow diagram illustrating a method 1600 for operating a network entity implementing a location server 110 of the mobile communication network 100, wherein the network entity is configured to implement a location management function in a core network of the mobile communication network. The method 1600 comprises a step 1601 of receiving a sidelink positioning discovery configuration from one or more of the plurality of RAN nodes 120 of the mobile communication network 100, wherein the sidelink positioning discovery configuration indicates one or more resources and/or a configuration provided by the one or more RAN nodes 120 for transmission and/or reception of a sidelink positioning discovery signal by one or more of the plurality of UEs 130 of the mobile communication network 100. The method 1600 further comprises a step 1603 of transmitting sidelink positioning discovery information based on the sidelink positioning discovery configuration to one or more of the plurality of UEs 130 of the mobile communication network 100.

The method 1600 can be performed by the network entity implementing the location server 110 according to an embodiment. Thus, further features of the method 1600 result directly from the functionality of the location server 110 as well as the different embodiments thereof described above and below.

The person skilled in the art will understand that the "blocks" ("units") of the various figures (method and apparatus) represent or describe functionalities of embodiments of the present disclosure (rather than necessarily individual "units" in hardware or software) and thus describe equally functions or features of apparatus embodiments as well as method embodiments (unit = step).

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus, and method may be implemented in other manners. For example, the described embodiment of an apparatus is merely exemplary. For example, the unit division is merely a logical function division and may be another division in an actual implementation. For example, a plurality of units or components may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented by using some interfaces. The indirect couplings or communication connections between the apparatuses or units may be implemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.

In addition, functional units in the embodiments of the disclosure may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units may be integrated into one unit.

Claims

1 . A user equipment, UE, (130) for a mobile communication network (100), wherein the UE (130) is configured to: receive sidelink positioning discovery information from a network node (110, 120) of the mobile communication network (100); transmit a sidelink positioning discovery signal based on the sidelink positioning discovery information; and/or receive a sidelink positioning discovery signal based on the sidelink positioning discovery information.

2. The UE (130) of claim 1 , wherein the UE (130) is configured to discover a further UE (130) based on the sidelink positioning discovery signal for performing sidelink positioning with the further UE (130).

3. The UE (130) of claim 1 or 2, wherein the sidelink positioning discovery information comprises one or more of: time-frequency scheduling information of the sidelink positioning discovery signal; one or more network identifiers indicative of one or more networks for which the sidelink positioning discovery information applies; and geographical information indicative of one or more geographical regions for which the sidelink positioning discovery information applies.

4. The UE (130) of any one of the preceding claims, wherein the UE (130) is configured to transmit the sidelink positioning discovery signal based on the sidelink positioning discovery information and wherein the sidelink positioning discovery information comprises one or more of: information indicative of a transmission power for transmitting the sidelink positioning discovery signal; spatial direction information for transmitting the sidelink positioning discovery signal; and/or

28 information indicative of one or more triggering conditions for triggering the transmission of the sidelink positioning discovery signal.

5. The UE (130) of any one of the preceding claims, wherein the UE (130) is further configured to receive a sidelink positioning discovery measurement report request from the network node (110, 120) and to receive the sidelink positioning discovery signal, wherein the UE (130) is configured to generate a sidelink positioning discovery measurement report based on the sidelink positioning discovery measurement report request and the sidelink positioning discovery signal.

6. The UE (130) of claim 5, wherein the UE (130) is configured to transmit the sidelink positioning discovery measurement report to the network node (110, 120) and/or a further UE (130) of the mobile communication network (100), wherein the network node (110, 120) comprises a location server (110) or a RAN node (120).

7. The UE (130) of claim 5 or 6, wherein the sidelink positioning discovery measurement report request comprises one or more of: information indicative of one or more measurements related to the sidelink positioning discovery signal; information indicative of one or more measurements on a downlink and/or an uplink signal; information indicative of one or more RAN node identities associated with the UE (130); information indicative of a reporting threshold for the sidelink positioning discovery measurement report in terms of a measurement quality indication; information indicative of a destination of the sidelink positioning discovery measurement report; and information about a number, a periodicity and/or a start time of the sidelink positioning discovery measurement report and one or more further sidelink positioning discovery measurement reports.

8. The UE (130) of any one of the preceding claims, wherein the sidelink positioning discovery signal comprises one or more of the following: a pre-defined physical signal associated with the UE (130); a data payload; and a reference signal for demodulation and measurements.

9. The UE (130) of claim 8, wherein the data payload comprises a sidelink positioning discovery measurement request and/or scheduling information for transmitting the sidelink positioning discovery measurement report to a further UE (130) of the mobile communication network (100) and/or the location server(110).

10. The UE (130) of any one of the preceding claims, wherein the UE (130) is further configured to transmit a sidelink positioning reference signal to a further UE (130) for determining a position of the UE (130) and/or the further UE (130).

11 . The UE (130) of any one of the preceding claims, wherein the UE (130) is further configured to receive a sidelink positioning reference signal from a further UE (130) and to determine a position of the UE (130) and/or the further UE (130) based on the received sidelink positioning reference signal.

12. A method (1400) of operating a user equipment, UE, (130) for a mobile communication network (100), wherein the method (1400) comprises: receiving (1401) sidelink positioning discovery information from a network node (110, 120); transmitting (1403a) a sidelink positioning discovery signal based on the sidelink positioning discovery information; and/or receiving (1403b) a sidelink positioning discovery signal based on the sidelink positioning discovery information.

13. A radio access network, RAN, node (120), for a mobile communication network (100), wherein the RAN node (120) is configured to: transmit a sidelink positioning discovery configuration to a network entity implementing a location server (110) of the mobile communication network (100), wherein the sidelink positioning discovery configuration indicates one or more resources and/or a configuration provided by the RAN node (120) for transmission and/or reception of a sidelink positioning discovery signal by one or more UEs (130) of the mobile communication network (100).

14. The RAN node (120) of claim 13, wherein the sidelink positioning discovery configuration comprises one or more of: information about time-frequency allocation and/or a configuration of the sidelink positioning discovery signal; information about one or more carrier frequency indices or frequency band indicators with respect to the sidelink capability of the RAN node (120), the one or more UEs (130) and/or a further UE (130) receiving the sidelink positioning discovery signal; one or more network identifiers indicative of one or more networks for which the sidelink positioning discovery configuration applies; and information indicating that one or more sidelink radio resources are intended for sidelink positioning discovery and/or sidelink positioning measurement.

15. The RAN node (120) of claim 13 or 14, wherein the sidelink positioning discovery configuration comprise one or more configuration parameters and/or one or more indications indicative of one or more pre-defined configuration parameters.

16. The RAN node (120) of any one of claims 13 to 15, wherein the RAN node is configured to transmit a sidelink positioning discovery configuration to the network entity implementing the location server (110), in response to receiving a sidelink positioning discovery configuration request from the network entity implementing the location server (110).

17. The RAN node (120) of claim 16, wherein the sidelink positioning discovery configuration request comprises one or more of: information about one or more parameters for generating the sidelink positioning discovery signal; an indication about a selected sidelink positioning discovery configuration of a plurality of pre-defined sidelink positioning discovery configurations; and information about an identity of the one or more UEs (130) and/or an identity of a further UE (130) transmitting and/or receiving the sidelink positioning discovery signal.

18. The RAN node (120) of any one of claims 13 to 17, wherein the RAN node (120) is configured to: transmit sidelink positioning discovery information to the one or more UEs (130); and/or receive sidelink positioning discovery information from the network entity implementing the location server (110).

19. A method (1500) of operating a radio access network, RAN, node (120) for a mobile communication network (100), wherein the method (1500) comprises: transmitting (1501) a sidelink positioning discovery configuration to a network entity implementing a location server (110) of the mobile communication network (100), wherein the sidelink positioning discovery configuration indicates one or more resources and/or a configuration provided by the RAN node (120) for transmission and/or reception of a sidelink positioning discovery signal by one or more UEs (130) of the mobile communication network (100).

20. A network entity (110) of a mobile communication network (100), wherein the network entity (110) is configured to implement a location server (110) of the mobile communication network (100), wherein the location server (110) is configured to: receive a sidelink positioning discovery configuration from one or more RAN nodes (120) of the mobile communication network (100), wherein the sidelink positioning discovery configuration indicates one or more resources and/or a configuration provided by the one or more RAN nodes (120) for transmission and/or reception of a sidelink positioning discovery signal by an UE (130) of the mobile communication network (100); and transmit sidelink positioning discovery information based on the sidelink positioning discovery configuration to one or more UEs (130) of the mobile communication network (100).

21 . The network entity (110) of claim 20, wherein the location server (110) is configured to generate the sidelink positioning discovery information based on the sidelink positioning discovery configuration.

22. The network entity (110) of claim 20 or 21 , wherein the location server (110) is further configured to transmit a sidelink positioning discovery configuration request to at least one RAN node (120) of the mobile communication network (100) and to receive a sidelink positioning discovery configuration in response to the sidelink positioning

32 discovery configuration request for transmitting and/or receiving a sidelink positioning discovery signal by one or more UEs (130) of the mobile communication network (100).

23. The network entity (110) of claim 22, wherein the sidelink positioning discovery configuration request comprises one or more of: one or more parameters for generating the sidelink positioning discovery signal; an indication about a selected sidelink positioning discovery configuration of a plurality of pre-defined sidelink positioning discovery configurations; and information about an identity of one or more UEs (130).

24. The network entity (110) of claim 22 or 23, wherein the location server (110) is further configured to transmit the sidelink positioning discovery configuration request, in response to one or more of: a request from the one or more UEs (130); a request from a further entity; an insufficient positioning accuracy of the one or more UEs (130); and an insufficient measurement quality on a downlink and/or an uplink of the one or more UEs (130).

25. The network entity (110) of any one of claims 20 to 24, wherein the sidelink positioning discovery information comprises one or more of: information about time-frequency allocation and/or a configuration of the sidelink positioning discovery signal; information about one or more carrier frequency indices or frequency band indicators with respect to the sidelink capability of the RAN node (120), the one or more UEs (130) and/or a further UE (130); one or more network identifiers indicative of one or more networks for which the sidelink positioning discovery information applies; and information indicating that the one or more sidelink radio resources are intended for sidelink positioning discovery and/or sidelink positioning measurement.

26. The network entity (110) of any one of claims 20 to 25, wherein the sidelink positioning discovery information comprises one or more of: information indicative of a transmission power for transmitting the sidelink positioning discovery signal by the one or more UEs (130);

33 spatial direction information for transmitting the sidelink positioning discovery signal by the one or more UEs (130); and/or information indicative of one or more triggering conditions for triggering the transmission of the sidelink positioning discovery signal.

27. The network entity (110) of any one of claims 20 to 26, wherein the location server (110) is configured to transmit a sidelink positioning discovery measurement report request to one or more UEs (130) and to receive a sidelink positioning discovery measurement report from one or mores UE (130) based on the sidelink positioning discovery measurement report request.

28. The network entity (110) of any one of claims 20 to 27, wherein the location server (110) is configured to determine the UE (130) for transmitting a sidelink positioning reference signal to a further UE (130) and/or receiving a sidelink positioning reference signal from a further UE (130) for determining a position of the UE (130) and/or the further UE (130).

29. A method (1600) of operating a network entity (110) of a mobile communication network (100), wherein the network entity (110) is configured to implement a location server (110) of the mobile communication network (100), wherein the method (1600) comprises: receiving (1601) a sidelink positioning discovery configuration from one or more RAN nodes (120) of the mobile communication network (100), wherein the sidelink positioning discovery configuration indicates one or more resources and/or a configuration provided by the one or more RAN nodes (120) for transmission and/or reception of a sidelink positioning discovery signal by one or more UEs (130) of the mobile communication network (100); and transmitting (1603) sidelink positioning discovery information based on the sidelink positioning discovery configuration to one or more UEs (130) of the mobile communication network (100).

30. A computer program product comprising a computer-readable storage medium for storing program code which causes a computer or a processor to perform the method

34 (1400) of claim 12, the method (1500) of claim 19, or the method (1600) of claim 29 when the program code is executed by the computer or the processor.

35