Reference information for reference signal time difference

Abstract

A method is disclosed that includes: selecting at least one user device from one or more candidate user devices as a reference for reference signal time difference, RSTD, measurements; measuring RSTD between at least two reference signals, the at least two reference signals including at least sidelink positioning reference signals (SLRSs) received from the at least one user device selected as the reference; and transmitting a report including at least one of an identifier of the at least one user device selected as the reference for RSTD measurements, an identifier of a resource associated with the SLRSs received from the at least one user device, synchronization resource information indicating at least one synchronization resource for the at least one user device, or a timestamp of the SLRSs received from the at least one user device.

Description

[Technical Field]

[0001] The following exemplary embodiments relate to wireless communications and positioning. [Background technology]

[0002] Positioning techniques may be used to estimate the physical location of a device. It is desirable to improve positioning accuracy to more accurately estimate the location of a device. Summary of the Invention

[0003] The scope of protection sought for various exemplary embodiments is set forth in the independent claims. The exemplary embodiments and features described herein that do not fall within the scope of the independent claims, if any, are to be construed as examples useful for understanding the various embodiments.

[0004] According to an aspect, there is provided an apparatus in a radio access network comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: select at least one user device from one or more candidate user devices as a reference for reference signal time difference (RSTD) measurements; measure RSTD between at least two reference signals, the at least two reference signals including at least one sidelink positioning reference signal (SLRS) received from the at least one user device selected as the reference; and transmit a report to a network element of a core network, the report including at least one of an identifier of the at least one user device selected as reference for RSTD measurements, an identifier of a resource associated with the SLRS received from the at least one user device, synchronization resource information indicating at least one synchronization resource for the at least one user device, or a timestamp of the SLRS received from the at least one user device.

[0005] According to another aspect, an apparatus in a radio access network is provided, comprising: means for selecting at least one user device from one or more candidate user devices as a reference for reference signal time difference (RSTD) measurements; means for measuring RSTD between at least two reference signals, the at least two reference signals including at least a sidelink positioning reference signal (SLRS) received from the at least one user device selected as the reference; and means for transmitting to a network element of a core network a report comprising at least one of an identifier of the at least one user device selected as the reference for RSTD measurements, an identifier of a resource associated with the SLRS received from the at least one user device, synchronization resource information indicating at least one synchronization resource for the at least one user device, or a timestamp of the SLRS received from the at least one user device.

[0006] According to another aspect, there is provided a method, the method comprising: selecting, by an apparatus in a radio access network, at least one user device from one or more candidate user devices as a reference for reference signal time difference (RSTD) measurements; measuring, by the apparatus, RSTD between at least two reference signals, the at least two reference signals including at least one sidelink positioning reference signal (SLRS) received from the at least one user device selected as the reference; and transmitting, by the apparatus, a report to a network element of a core network, the report comprising at least one of an identifier of the at least one user device selected as the reference for RSTD measurements, an identifier of a resource associated with the SLRS received from the at least one user device, synchronization resource information indicating at least one synchronization resource for the at least one user device, or a timestamp of the SLRS received from the at least one user device.

[0007] According to another aspect, there is provided a computer program comprising instructions that, when executed by an apparatus in a radio access network, cause the apparatus to at least: select at least one user device from one or more candidate user devices as a reference for reference signal time difference (RSTD) measurements; measure RSTD between at least two reference signals, the at least two reference signals including at least sidelink positioning reference signals (SLRSs) received from the at least one user device selected as the reference; and transmit a report to a network element of a core network, the report comprising at least one of an identifier of the at least one user device selected as reference for RSTD measurements, an identifier of a resource associated with the SLRSs received from the at least one user device, synchronization resource information indicating at least one synchronization resource for the at least one user device, or a timestamp of the SLRSs received from the at least one user device.

[0008] According to another aspect, there is provided a computer-readable medium comprising program instructions that, when executed by an apparatus in a radio access network, cause the apparatus to at least: select at least one user device from one or more candidate user devices as a reference for reference signal time difference (RSTD) measurements; measure RSTD between at least two reference signals, the at least two reference signals including at least a sidelink positioning reference signal (SLRS) received from the at least one user device selected as the reference; and transmit a report to a network element of a core network, the report including at least one of an identifier of the at least one user device selected as reference for RSTD measurements, an identifier of a resource associated with the SLRS received from the at least one user device, synchronization resource information indicating at least one synchronization resource for the at least one user device, or a timestamp of the SLRS received from the at least one user device.

[0009] According to another aspect, there is provided a non-transitory computer-readable medium comprising program instructions that, when executed by an apparatus in a radio access network, cause the apparatus to at least: select at least one user device from one or more candidate user devices as a reference for reference signal time difference (RSTD) measurements; measure RSTD between at least two reference signals, the at least two reference signals including at least sidelink positioning reference signals (SLRSs) received from the at least one user device selected as the reference; and transmit a report to a network element of a core network, the report including at least one of an identifier of the at least one user device selected as reference for RSTD measurements, an identifier of a resource associated with the SLRSs received from the at least one user device, synchronization resource information indicating at least one synchronization resource for the at least one user device, or a timestamp of the SLRSs received from the at least one user device.

[0010] According to an aspect, there is provided an apparatus in a core network comprising: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to: receive from a target user device a report including at least one of: an identifier of at least one user device selected as a reference for measuring a reference signal time difference (RSTD), an identifier of a resource associated with a sidelink positioning reference signal (SLRS) used to measure the RSTD, synchronization resource information indicating at least one synchronization resource of the at least one user device selected as a reference for measuring the RSTD, or a timestamp of a sidelink positioning reference signal (SLRS) used to measure the RSTD; and estimate a location of the target user device based at least in part on the report.

[0011] According to another aspect, an apparatus in a core network is provided, the apparatus comprising: means for receiving from a target user device a report including at least one of an identifier of at least one user device selected as a reference for measuring a reference signal time difference (RSTD), an identifier of a resource associated with a sidelink positioning reference signal used to measure the RSTD, synchronization resource information indicating at least one synchronization resource of the at least one user device selected as a reference for measuring the RSTD, or a timestamp of the sidelink positioning reference signal used to measure the RSTD; and means for estimating a location of the target user device based at least in part on the report.

[0012] According to another aspect, there is provided a method, comprising: receiving, by an apparatus in a core network, from a target user device, a report including at least one of an identifier of at least one user device selected as a reference for measuring a reference signal time difference (RSTD), an identifier of a resource associated with a sidelink positioning reference signal used to measure the RSTD, synchronization resource information indicating at least one synchronization resource of the at least one user device selected as a reference for measuring the RSTD, or a timestamp of the sidelink positioning reference signal used to measure the RSTD; and estimating, by the apparatus, a location of the target user device based at least in part on the report.

[0013] According to another aspect, there is provided a computer program comprising instructions that, when executed by an apparatus in a core network, cause the apparatus to: receive from a target user device a report including at least one of an identifier of at least one user device selected as a reference for measuring a reference signal time difference (RSTD), an identifier of a resource associated with a sidelink positioning reference signal used to measure the RSTD, synchronization resource information indicating at least one synchronization resource of the at least one user device selected as a reference for measuring the RSTD, or a timestamp of the sidelink positioning reference signal used to measure the RSTD; and estimate a location of the target user device based at least in part on the report.

[0014] According to another aspect, there is provided a computer-readable medium comprising program instructions that, when executed by an apparatus in a core network, cause the apparatus to: receive from a target user device a report including at least one of an identifier of at least one user device selected as a reference for measuring a reference signal time difference (RSTD), an identifier of a resource associated with a sidelink positioning reference signal used to measure the RSTD, synchronization resource information indicating at least one synchronization resource of the at least one user device selected as a reference for measuring the RSTD, or a timestamp of a sidelink positioning reference signal used to measure the RSTD; and estimate a location of the target user device based at least in part on the report.

[0015] According to another aspect, there is provided a non-transitory computer-readable medium comprising program instructions that, when executed by an apparatus in a core network, cause the apparatus to: receive from a target user device a report including at least one of an identifier of at least one user device selected as a reference for measuring a reference signal time difference (RSTD), an identifier of a resource associated with a sidelink positioning reference signal (SLRS) used to measure the RSTD, synchronization resource information indicating at least one synchronization resource of the at least one user device selected as a reference for measuring the RSTD, or a timestamp of a sidelink positioning reference signal (SLRS) used to measure the RSTD; and estimate a location of the target user device based at least in part on the report.

[0016] According to an aspect, there is provided an apparatus in a radio access network comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least receive, from a network element of a core network, a threshold value for a time difference between receiving a downlink positioning reference signal and transmitting a sidelink positioning reference signal, and transmit, to a target user device, the sidelink positioning reference signal based on at least the threshold value, wherein the time difference between receiving the downlink positioning reference signal and transmitting the sidelink positioning reference signal is less than the threshold value.

[0017] According to another aspect, there is provided an apparatus in a radio access network, comprising: means for receiving, from a network element of a core network, a threshold for a time difference between receiving a downlink positioning reference signal and transmitting a sidelink positioning reference signal; and means for transmitting, to a target user device, the sidelink positioning reference signal based on at least the threshold, wherein the time difference between receiving the downlink positioning reference signal and transmitting the sidelink positioning reference signal is less than the threshold.

[0018] According to another aspect, there is provided a method, the method comprising: receiving, by an apparatus in a radio access network, from a network element of a core network, a threshold value for a time difference between receiving a downlink positioning reference signal and transmitting a sidelink positioning reference signal; and transmitting, by the apparatus, a sidelink positioning reference signal to a target user device based on at least the threshold value, wherein the time difference between receiving the downlink positioning reference signal and transmitting the sidelink positioning reference signal is less than the threshold value.

[0019] According to another aspect, there is provided a computer program comprising instructions that, when executed by an apparatus in a radio access network, cause the apparatus to at least: receive from a network element of a core network a threshold value for a time difference between receiving a downlink positioning reference signal and transmitting a sidelink positioning reference signal; and transmit the sidelink positioning reference signal to a target user device based on at least the threshold value, wherein the time difference between receiving the downlink positioning reference signal and transmitting the sidelink positioning reference signal is less than the threshold value.

[0020] According to another aspect, there is provided a computer-readable medium comprising program instructions that, when executed by an apparatus in a radio access network, cause the apparatus to at least receive from a network element of a core network a threshold value for a time difference between receiving a downlink positioning reference signal and transmitting a sidelink positioning reference signal, and transmit the sidelink positioning reference signal to a target user device based on at least the threshold value, wherein the time difference between receiving the downlink positioning reference signal and transmitting the sidelink positioning reference signal is less than the threshold value.

[0021] According to another aspect, there is provided a non-transitory computer-readable medium comprising program instructions that, when executed by an apparatus in a radio access network, cause the apparatus to at least: receive from a network element of a core network a threshold value for a time difference between receiving a downlink positioning reference signal and transmitting a sidelink positioning reference signal; and transmit, based on at least the threshold value, the sidelink positioning reference signal to a target user device, wherein the time difference between receiving the downlink positioning reference signal and transmitting the sidelink positioning reference signal is less than the threshold value.

[0022] In the following, various exemplary embodiments will be described in more detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 illustrates an example of a cellular communication network. [Figure 2] FIG. 10 illustrates an example of a time difference of arrival from a sidelink positioning reference signal and a downlink positioning reference signal. [Figure 3] 1 is a signal transmission diagram in accordance with an exemplary embodiment; [Figure 4] 1 is a signal transmission diagram in accordance with an exemplary embodiment; [Figure 5] 1 is a signal transmission diagram in accordance with an exemplary embodiment; [Figure 6] 1 is a flowchart according to an example embodiment. [Figure 7] 1 is a flowchart according to an example embodiment. [Figure 8] 1 is a flowchart according to an example embodiment. [Figure 9] FIG. 1 illustrates an example of an apparatus. [Figure 10] FIG. 1 illustrates an example of an apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0024] The following embodiments are illustrative. Although this specification may refer to "an," "one," or "some" embodiments in several places in the text, this does not necessarily mean that each reference is to the same embodiment or that a particular feature only applies to a single embodiment. Single features of different embodiments may be combined to provide other embodiments.

[0025] In the following, different exemplary embodiments are described using radio access architectures based on Long Term Evolution Advanced (LTE-A), New Radio (NR, 5G), beyond 5G, or sixth generation (6G) as examples of access architectures to which the exemplary embodiments may be applied, without, however, limiting the exemplary embodiments to such architectures. It will be clear to those skilled in the art that the exemplary embodiments may also be applied to other types of communication networks with appropriate means by appropriately adjusting parameters and procedures. Some examples of other options for suitable systems may be a universal mobile telecommunications system (UMTS) radio access network (UTRAN or E-UTRAN), Long Term Evolution (LTE, essentially the same as E-UTRAN), a wireless local area network (WLAN or Wi-Fi), Worldwide Interoperability for Microwave Access (WiMAX), Bluetooth, personal communications services (PCS), ZigBee, wideband code division multiple access (WCDMA), systems using ultra-wideband (UWB) technology, sensor networks, mobile ad-hoc networks (MANET), and Internet Protocol multimedia subsystem (IMS), or any combination thereof.

[0026] 1 shows an example of a simplified system architecture showing several elements and functional entities, all of which are logical units whose implementation may differ from that shown. The connections shown in FIG. 1 are logical connections; the actual physical connections may differ. It will be apparent to one skilled in the art that the system may have functions and structures other than those shown in FIG. 1.

[0027] The exemplary embodiment is however not limited to the system given as an example, and a person skilled in the art may apply the solution to other communication systems that have the required characteristics.

[0028] The example of FIG. 1 shows a portion of an exemplary radio access network.

[0029] FIG. 1 illustrates an access node (AN) 104, such as an evolved Node B (eNB, abbreviated as eNodeB) or next generation Node B (gNB, abbreviated as gNodeB), providing a radio cell, and user devices 100 and 102 configured to be wirelessly connected with one or more communication channels within the radio cell. The physical link from the user device to the access node may be referred to as an uplink (UL) or reverse link, and the physical link from the access node to the user device may be referred to as a downlink (DL) or forward link. A user device may communicate directly with another user device via sidelink (SL) communication. It should be appreciated that the access node or its functionality may be performed by using any node, host, server, or access point, or other entity suitable for such use.

[0030] A communication system may include two or more access nodes, in which case the access nodes may be configured to communicate with each other through links (wired or wireless) designed for that purpose. These links may be used for signal transmission and also for routing data from one access node to another. An access node may be a computing device configured to control radio resources of a communication system to which the access node is coupled. An access node may also be referred to as a base station, base transceiver station (BTS), access point, or any other type of interfacing device, including a relay station, capable of operating in a wireless environment. An access node may include or be coupled to a transceiver. From the access node's transceiver, a connection may be provided to an antenna unit that establishes a bidirectional radio link to a user device. The antenna unit may include multiple antennas or antenna elements. The access node may be further connected to a core network 110 (core network (CN) or next generation core (NGC)). Depending on the deployed technology, the access node may be connected on the CN side to a serving gateway (S-GW, routes and forwards user data packets), packet data network gateway (P-GW) for providing user device connectivity to external packet data networks, user plane function (UPF), mobility management entity (MME), or access and mobility management function (AMF), etc.

[0031] With regard to positioning, the service-based architecture (core network) may comprise an AMF 111 and a location management function (LMF) 112. The AMF may provide location information for call processing, policy, and billing to other network functions in the core network and other entities that request positioning of terminal devices. The AMF may receive and manage location requests from several sources: mobile-originated location requests (MO-LR) from user devices and mobile-terminated location requests (MT-LR) from other functions in the core network or from other network elements. The AMF may select an LMF for a given request and use its positioning service to trigger a positioning session. The LMF may then perform positioning upon receiving such a request from the AMF. The LMF may manage resources and timing of positioning activities. The LMF may use the Namf_Communication service over the NL1 interface to request positioning of the user device from one or more access nodes, or the LMF may communicate with the user device through N1 for UE-based or UE-assisted positioning. The positioning may include an estimation of the location, and the LMF may also estimate the movement or accuracy of the location information when requested. In relation to the connection, the AMF is between the access node and the LMF and may therefore be closer to the access node than the LMF.

[0032] A user device represents one type of device to which resources over the air interface may be allocated and assigned, and therefore any features described herein with respect to a user device may also be implemented using a corresponding device such as a relay node.

[0033] An example of such a relay node may be a Layer 3 relay (self-backhauling relay) for an access node. A self-backhauling relay node may also be called an integrated access and backhaul (IAB) node. An IAB node may comprise two logical parts: a mobile termination (MT) part that handles the backhaul link (i.e., the link between the IAB node and a donor node, also known as a parent node), and a distributed unit (DU) part that handles the access link (i.e., the child link between the IAB node and a user device and / or between the IAB node and other IAB nodes (multi-hop scenarios).

[0034] Another example of such a relay node may be a Layer 1 relay, called a repeater, which may amplify signals received from an access node and forward the signals to a user device and / or may amplify signals received from a user device and forward the signals to the access node.

[0035] A user device may be referred to as a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, or user equipment (UE), to name a few. A user device may refer to a portable computing device, including a wireless mobile communication device operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: mobile station (mobile phone), smartphone, personal digital assistant (PDA), handset, device using a wireless modem (such as an alarm or measurement device), laptop and / or touchscreen computer, tablet, game console, notebook, multimedia device, reduced capability (RedCap) device, wireless sensor device, or any device integrated into a vehicle.

[0036] It should be appreciated that a user device may be almost exclusively an uplink-only device, an example of which may be a camera or video camera that loads images or video clips onto the network. A user device may also be a device capable of operating in an Internet of Things (IoT) network, a scenario in which objects may have the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction. A user device may utilize the cloud. In some applications, a user device may comprise a small, portable, or wearable device with wireless components (such as a watch, earphones, or glasses), and computation may be performed in the cloud or in another user device. A user device (or, in some exemplary embodiments, a Layer 3 relay node) may be configured to perform one or more of the user equipment functions.

[0037] The various techniques described herein may be applied to cyber-physical systems (CPSs)—systems of cooperating computational elements that control physical entities. CPSs may enable the execution and utilization of vast numbers of interconnected ICT devices (sensors, actuators, processors, microcontrollers, etc.) embedded in physical objects at different locations. Mobile cyber-physical systems, in which the physical systems in question may have inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals.

[0038] Furthermore, although the device is shown as a single entity, it may be implemented as different units, processors and / or memory units (not all shown in FIG. 1).

[0039] 5G allows for many more base stations or nodes than LTE (the so-called small cell concept), including macro sites operating in cooperation with smaller stations using multiple input-multiple output (MIMO) antennas and employing various radio technologies depending on service needs, use cases, and / or available spectrum. 5G mobile communications may support a wide range of use cases and related applications, including video streaming, augmented reality, different methods of data sharing, and various forms of machine-type applications (such as massive machine-type communication (mMTC) including vehicle safety, different sensors, and real-time control). 5G may have multiple air interfaces, namely, sub-6 GHz, cm-wave, and mm-wave, and may also be integrated with existing legacy radio access technologies such as LTE. Integration with LTE may be performed, at least in early phases, as a system in which macro coverage may be provided by LTE and 5G air interface access may come from small cells through aggregation to LTE. In other words, 5G may support both inter-RAT interoperability (e.g., LTE-5G) and inter-RI interoperability (interoperability between air interfaces such as sub-6 GHz-cm wave-mm wave). One concept that may be used in 5G networks may be network slicing, in which multiple independent and dedicated virtual sub-networks (network instances) may be created within substantially the same infrastructure to run services with different requirements in terms of latency, reliability, throughput, and mobility.

[0040] The current architecture in LTE networks may be fully distributed in the radio and fully centralized in the core network. Low-latency applications and services in 5G may require content to be closer to the radio, which leads to local breakout and multi-access edge computing (MEC). 5G may enable analytics and knowledge generation to occur at the source of the data. This approach may require effective utilization of resources that may not be continuously connected to the network, such as laptops, smartphones, tablets, and sensors. MEC may provide a distributed computing environment for application and service hosting. MEC may have the ability to store and process content close to cellular subscribers for faster response times. Edge computing may cover a wide range of technologies, such as wireless sensor networks, mobile data acquisition, mobile signature analysis, collaborative distributed peer-to-peer ad hoc networking, and processing that can also be categorized as cloud / fog computing and grid / mesh computing, dew computing, mobile edge computing, cloudlets, distributed data storage and retrieval, autonomous self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and / or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications).

[0041] The communications system may be able to communicate with or use services provided by one or more other networks 113, such as the public switched telephone network or the Internet. The communications network may be able to support the use of cloud services, e.g., at least part of the core network operations may be implemented as cloud services (this is illustrated in FIG. 1 by "cloud" 114). The communications system may comprise a central control entity or the like that provides facilities for networks of different operators to cooperate, e.g., in spectrum sharing.

[0042] An edge cloud may be joined to a radio access network (RAN) by utilizing network function virtualization (NFV) and software defined networking (SDN). Using an edge cloud may mean that access node operations are at least partially implemented in a server, host, or node operatively coupled to a remote radio head (RRH) or radio unit (RU), or an access node comprising a radio part. It is also possible that node operations may be distributed among multiple servers, nodes, or hosts. Application of a Cloud RAN architecture allows RAN real-time functions to be implemented on the RAN side (in the distributed unit, DU 105) and non-real-time functions to be implemented in a centralized manner (in the central unit, CU 108).

[0043] It should also be understood that the distribution of functions between core network operations and access node operations may differ from or even not exist in LTE. Some other technological advances that may be used include big data and all-IP, which may change the way networks are built and managed. 5G (or New Radio, NR) networks may be designed to support multiple hierarchies in which MEC servers may be located between the core and access nodes. It should be recognized that MEC may also be applied in 4G networks.

[0044] 5G may utilize non-terrestrial communications, such as satellite communications, to augment or complement 5G service coverage by providing backhauling. Potential use cases may include providing service continuity for machine-to-machine (M2M) or Internet of Things (IoT) devices or for passengers aboard vehicles, or ensuring service availability for critical communications and future rail, maritime, and aviation communications. Satellite communications may utilize geostationary earth orbit (GEO) satellite systems, as well as low earth orbit (LEO) satellite systems, particularly mega-constellations (systems in which hundreds of (nano)satellites are deployed). A given satellite 106 in a mega-constellation may cover several satellite-enabled network entities, creating on-ground cells. On-ground cells may be created through on-ground relay nodes or by access nodes 104 located on-ground or within the satellite.

[0045] 6G networks are expected to employ flexible decentralized and / or distributed computing systems and architectures and ubiquitous computing, with local spectrum licensing, spectrum sharing, infrastructure sharing, and intelligent automated management underpinned by mobile edge computing, artificial intelligence, short packet communications, and blockchain technologies. Key features of 6G may include intelligent connected management and control capabilities, programmability, integrated sensing and communications, reduced energy footprint, reliable infrastructure, scalability, and affordability. In addition, 6G also opens up new use cases covering the integration of location and sensing capabilities to system definitions for unifying user experiences across the physical and digital worlds.

[0046] It is apparent to those skilled in the art that the illustrated system is only a partial example of a wireless access system, and in practice, the system may include multiple access nodes, a user device may be able to access multiple wireless cells, and the system may include other devices such as physical layer relay nodes or other network elements, etc. At least one of the access nodes may be a Home eNodeB or a Home gNodeB.

[0047] Furthermore, an access node may be divided into a radio unit (RU) comprising a radio transceiver (TRX), i.e., a transmitter (Tx) and a receiver (Rx), one or more distributed units (DUs) that may be used for so-called Layer 1 (L1) processing and real-time Layer 2 (L2) processing, and a central unit (CU) (also known as a centralized unit) that may be used for non-real-time L2 and Layer 3 (L3) processing. The CU may be connected to one or more DUs, for example, by using an F1 interface. Such a division may enable centralization of the CU with respect to the cell site and the DU, while the DU may be more decentralized and remain at the cell site. The CU and DU together may be referred to as a baseband or baseband unit (BBU). The CU and DU may be included in a radio access point (RAP).

[0048] A CU may be defined as a logical node that hosts higher layer protocols, such as radio resource control (RRC), service data adaptation protocol (SDAP), and / or packet data convergence protocol (PDCP), of an access node. A DU may be defined as a logical node that hosts radio link control (RLC), medium access control (MAC), and / or physical (PHY) layers of an access node. The operation of the DU may be at least partially controlled by the CU. A CU may comprise a control plane (CU-CP), which may be defined as a logical node that hosts RRC and the control plane portion of the CU's PDCP protocol for the access node. A CU may further comprise a user plane (CU-UP), which may be defined as a logical node that hosts the user plane portion of the CU's PDCP and SDAP protocols for the access node.

[0049] A cloud computing platform may be used to run the CU and / or DU. The CU may run on the cloud computing platform, which may be referred to as a virtualized CU (vCU). In addition to the vCU, there may be a virtualized DU (vDU) running on the cloud computing platform. Furthermore, a combination may exist, where the DU may use a so-called bare-metal solution, e.g., an application-specific integrated circuit (ASIC) or a customer-specific standard product (CSSP) system-on-a-chip (SoC) solution. It should also be understood that the distribution of functionality between the above-mentioned access node units or between different core network operations and access node operations may vary.

[0050] Furthermore, within the geographical area of ​​the wireless communication system, multiple radio cells of different types may be provided. The radio cells may be macrocells (or umbrella cells), which may be large cells with a diameter of up to tens of kilometers, or small cells such as microcells, femtocells, or picocells. The access nodes of FIG. 1 may provide any type of these nodes. The cellular wireless system may be implemented as a multi-layer network including several types of radio cells. In a multi-layer network, one access node may provide one or more radio cells of one type, and therefore multiple access nodes may be required to provide such a network structure.

[0051] To achieve the need for improved deployment and performance of communication systems, the concept of a "plug-and-play" access node may be introduced. A network that may be able to use the "plug-and-play" access node may include a Home Node B gateway or HNB-GW (not shown in FIG. 1) in addition to a Home eNodeB or Home gNodeB. The HNB-GW, which may be installed in an operator's network, may aggregate traffic from multiple Home eNodeBs or Home gNodeBs back to the core network.

[0052] Positioning techniques may be used to estimate the physical location of a user device. Herein, a user device to be positioned is referred to as a target UE or target user device. In wireless positioning, multiple positioning anchors at known locations may transmit and / or receive one or more positioning reference signals (PRS) to / from the target UE. In the uplink, a sounding reference signal (SRS) may be used as the positioning reference signal. For example, a multilateration technique may then be used to locate (position) the target UE with respect to the positioning anchor. A positioning anchor may also be referred to herein as an anchor, anchor node, multilateration anchor, or reference point. A positioning anchor may be, for example, a radio access node (in uplink / downlink positioning), a transmission and reception point (TRP) (in uplink / downlink positioning), or another UE (in sidelink positioning).

[0053] Sidelink (SL) positioning refers to a positioning approach in which a target UE utilizes the sidelink (i.e., the PC5 interface) to position itself in an absolute manner (in the case of absolute positioning, where the target UE's coordinates are obtained in the form of global or local Cartesian coordinates) or in a relative manner (in the case of relative positioning, where the target UE's location is estimated with respect to another entity, e.g., another non-stationary or anchor UE). In the case of UE-assisted positioning, the target UE utilizes the sidelink to obtain positioning measurements and reports the measurements to a network entity, such as a location management function (LMF). Sidelink positioning may also be used to obtain ranging information. Ranging refers to determining the distance and / or direction between the target UE and another entity, such as an anchor UE.

[0054] Sidelink positioning involves the use of a supporting UE or a set of supporting UEs, called "anchor UE(s)," to assist the target UE in its positioning session. Anchor UE support can be performed in various ways, including the anchor UE estimating the target UE's location, the anchor UE providing positioning assistance data to the target UE over the sidelink, and / or the anchor UE transmitting and / or receiving reference signals, such as sidelink positioning reference signals (SL PRS), to / from the target UE for positioning.

[0055] The SL PRS is a reference signal transmitted over the sidelink for positioning. The SL PRS (pre-)configuration may include at least one of the (pre-)configured parameters of the SL PRS such as its bandwidth, time-frequency resources including periodicity, an identifier associated with the sidelink positioning reference signal resource, and an identifier associated with a set of sidelink positioning reference signal resources (other parameters are not excluded).

[0056] For example, in NR, the following positioning techniques may be used: downlink time difference of arrival (DL-TDOA), uplink time difference of arrival (UL-TDOA), downlink angle of departure (DL-AoD), uplink angle of arrival (UL-AoA), and / or multi-cell round trip time (multi-RTT). RAT-dependent and RAT-independent NR positioning techniques may both be used. RAT is an abbreviation for Radio Access Technology.

[0057] DL-TDOA and UL-TDOA were introduced in NR Release 16 and further enhanced in NR Release 17. To perform trilateration and estimate the location of a target UE, DL-TDOA techniques rely on measuring the reference signal time difference (RSTD) of DL positioning reference signals transmitted from multiple TRP locations, while UL-TDOA techniques rely on relative time of arrival (RTOA) measurements measured at multiple TRP locations. One drawback of TDOA techniques is the need for strict synchronization between TRPs to have high positioning accuracy.

[0058] As explained above, DL-TDOA relies on RSTD measurements, where the target UE measures the relative time of arrival to a reference. The reporting of this measurement in the NR Release 17 specification (TS.37.335) is as follows: NR-DL-TDOA-SignalMeasurementInformation-r16 ::= SEQUENCE { dl-PRS-ReferenceInfo-r16 DL-PRS-ID-Info-r16, nr-DL-TDOA-MeasList-r16 NR-DL-TDOA-MeasList-r16, ... } NR-DL-TDOA-MeasList-r16 ::= SEQUENCE (SIZE(1..nrMaxTRPs-r16)) OF NR-DL-TDOA-MeasElement-r16 NR-DL-TDOA-MeasElement-r16 ::= SEQUENCE { dl-PRS-ID-r16 INTEGER (0..255), nr-PhysCellID-r16 NR-PhysCellID-r16 OPTIONAL, nr-CellGlobalID-r16 NCGI-r15 OPTIONAL, nr-ARFCN-r16 ARFCN-ValueNR-r15 OPTIONAL, nr-DL-PRS-ResourceID-r16 NR-DL-PRS-ResourceID-r16 OPTIONAL, nr-DL-PRS-ResourceSetID-r16 NR-DL-PRS-ResourceSetID-r16 OPTIONAL, It can be seen as.

[0059] From the above, it can be seen that the measurement report for DL-TDOA depends on both the dl-PRS-ReferenceInfo-r16 and the resource ID or resource set ID of another PRS.

[0060] NR Release 16 / 17 positioning supported DL-TDOA techniques based on DL PRS. DL-TDOA techniques may require the target UE to measure multiple RSTD measurements from multiple TRPs and / or cells, and DL-TDOA techniques may require a single reference to calculate RSTD. In NR Release 16 / 17, single reference timing is determined based on a specific TRP, PRS resource set, and / or PRS resource.

[0061] In NR Release 18, TDOA techniques may be based on either or both SL PRS and DL PRS. However, the current specification is not sufficient to support hybrid sidelink time difference of arrival (SL-TDOA), which may use RSTD measurements from SL PRS and DL PRS. Similarly, the current specification is not sufficient to support SL-TDOA techniques, which may use RSTD measurements from two SL PRSs transmitted from two different UEs. These measurements may be referred to as SL RSTD measurements, TDOA measurements, or SL TDOA measurements. For example, without any changes to the specification, the target UE would not be able to use the SL PRS as a reference for RSTD measurements. Therefore, the target UE would report RSTD for the DL PRS and then RSTD for the SL PRS. Without RSTD between the reference DL PRS and the reference SL PRS, it may not be possible to use all reported RSTDs in a single positioning estimate.

[0062] Some example embodiments may provide configuration and reporting of RSTD measurement reference information to support TDOA based on DL and SL PRS. The reference information may be required to support DL-TDOA and higher layer signaling "dl-PRS-ReferenceInfo-r16" introduced in NR Release 16.

[0063] Some example embodiments may provide support for SL-TDOA through the SL PRS, and for hybrid SL-TDOA through the SL PRS and DL PRS.

[0064] It should be noted that RSTD may also be referred to as TDOA, but for simplicity, TDOA will be referred to herein as RSTD.

[0065] Some exemplary embodiments are described below using principles and terminology of 5G technology, however, without limiting the exemplary embodiments to 5G communication systems.

[0066] In some exemplary embodiments, the target UE measures RSTD from specific DL PRS resources and SL PRS resources. The LMF may or may not configure SL PRS resources. However, the target UE may use a different reference for RSTD than that configured by the LMF, so that the target UE selects the anchor UE and the SL PRS resources transmitted from the anchor UE for RSTD measurement reports. Similarly, the target UE may be able to use one or more RSTD references and report reference information.

[0067] If the target UE uses a single RSTD reference, the LMF may perform the location estimation algorithm using the single reference. The LMF may request the target UE to use a single RSTD reference for hybrid SL-TDOA from SL-PRS and DL-PRS resources. The LMF may instruct the target UE to use the RSTD reference from the anchor UE and / or SL PRS resources transmitted from the anchor UE with specific synchronization resources; other synchronization resources may not be allowed (e.g., an SL-UE using a gNB as its synchronization resource may be allowed, but an SL-UE using a global navigation satellite system as its synchronization resource may not be allowed). In this specification, SL-UE may refer to an anchor UE transmitting an SL PRS used as a reference for RSTD measurements. The target UE may report reference information to be used, which may include at least one of a specific anchor UE ID, an SL-PRS resource ID, synchronization resource information of the anchor UE (e.g., a cell ID or global navigation satellite system) if known by the target UE, a specific timestamp for the transmitted SL-PRS resource ID of the anchor UE, and / or the location of the anchor UE at that timestamp. The LMF may require a timestamp to determine the location of the anchor UE at a particular time if the target UE does not provide location information of the anchor UE.

[0068] For example, the target UE may report reference information including at least one of 1) an anchor UE ID, or 2) an anchor UE ID and an SL-PRS resource ID transmitted from the anchor UE. Furthermore, if one or more SL PRS resource sets are configured, the target UE may report reference information including at least an anchor UE ID, an SL PRS resource set ID, and an SL PRS resource ID, where the SL PRS resources are included in the SL PRS resource set and are transmitted from the anchor UE. The reported reference information may further include synchronization resource information and / or a timestamp.

[0069] As an example, assume that the LMF requests the target UE to use an SL-UE with synchronization resources of gNB#2 as an RSTD reference, and the synchronization resources of the SL-UE (e.g., denoted as UE#1) are gNB#2. An SL-UE with synchronization resources of gNB#2 means that the SL-UE is synchronized with gNB#2. In this case, the target UE may report the following RSTD measurements: RSTD from TRP#1 and UE#1, RSTD from TRP#2 and UE#1, and RSTD from UE#2 and UE#1. Note that TRP#1 and / or TRP#2 may be within gNB#2 or within a different gNB. If these TRP#1 and / or TRP#2 are within gNB#1, the LMF may compensate for the time synchronization error between gNB#1 and gNB#2 in the RSTD measurements. As the RSTD reference information, the target UE may report at least one of the SL-PRS resource, the ID of UE#1, and / or the timestamp of the SL-PRS transmission from UE#1.

[0070] If the target UE uses multiple RSTD references, the LMF may need to run the location estimation algorithm multiple times using different references. The UE may be permitted to use multiple RSTD references for hybrid SL-TDOA from SL-PRS and DL-PRS resources. The LMF may instruct the target UE to use one or more RSTD references from SL PRS resources with specific synchronization resources, or the LMF may provide a list of synchronization resources allowed for RSTD references. For example, an SL-UE using PCI#1 and PCI#2 as synchronization resources may be permitted for RSTD references. PCI stands for Physical Cell Identity. The target UE may report the reference information used, which may include a specific anchor UE ID, SL-PRS resource ID, the anchor UE's synchronization resource information (e.g., cell ID or global navigation satellite system), a specific timestamp for the anchor UE's transmitted SL-PRS resource ID, and the anchor UE's location at that timestamp, if the target UE knows it. The LMF may require a timestamp to determine the anchor UE's location at a specific time if the target UE does not provide the anchor UE's location information. This reporting of RSTD reference information may be reported in addition to the current reporting of the RSTD reference. For example, the target UE may be able to report two RSTD references, whereby the target UE may report a TRP ID (e.g., TRP#1), a PRS resource set ID, and / or a PRS resource ID via higher layer signaling (e.g., "dl-PRS-ReferenceInfo-r16"), and the target UE may also report an anchor UE ID (e.g., UE#1 ID), an SL-PRS resource ID, synchronization resource information (e.g., a cell ID), and a timestamp. Note that this timestamp does not indicate the measurement time for DL ​​PRS, but indicates the measurement time for the SL-PRS resource.

[0071] As an example, assume that the target UE measures the following RSTD measurements and reports them to the LMF, as described below with reference to FIG.

[0072] 2 shows an example of TDOA from SL PRSs and DL PRSs. In this example, a first TRP 211 (TRP#1) may transmit a first DL PRS (DL PRS#1) to a target UE 200. A second TRP 212 (TRP#2) may transmit a second DL PRS (DL PRS#2) to a target UE 200. A first UE 201 (UE#1) may transmit a first SL PRS (SL PRS#1) to a target UE 200. A second UE 202 (UE#2) may transmit a second SL PRS (SL PRS#2) to a target UE 200.

[0073] For example, the target UE 200 may use the first UE 201 (UE#1) and the second TRP 212 (TRP#2) as an RSTD reference for RSTD measurements. In this example, the target UE 200 may measure and report the following RSTD measurements to the LMF 220: RSTD from the first TRP 211 (TRP#1) and the first UE 201 (UE#1), RSTD from the second TRP 212 (TRP#2) and the first UE 201 (UE#1), RSTD from the second UE 202 (UE#2) and the first UE 201 (UE#1), RSTD from the first TRP 211 (TRP#1) and the second TRP 212 (TRP#2), and RSTD from the second UE 202 (UE#2) and the second TRP 212 (TRP#2). TRP#1 and / or TRP#2 may be within the same gNB or within different gNBs.

[0074] For example, assume that the synchronization resource of UE#1 is cell#1 and TRP#2 is located in cell#2. If the LMF knows the time synchronization information between cell#1 and cell#2, the LMF may modify the RSTD measurement so that the RSTD measurement has a single reference timing.

[0075] In one example, the target UE may inform the LMF whether the reference was used only for RSTD measurements between DL PRS resources or whether the reference was also used for RSTD measurements between DL PRS and SL PRS.

[0076] Of further note, the target UE may report one or more of the anchor UEs to the LMF as candidates for RSTD reference, and the target UE may propose a specific timestamp for the anchor UE to transmit the SL PRS.

[0077] When the target UE measures RSTD measurements from the SL PRS transmitted from the anchor UE, the LMF may need the location of the anchor UE at a particular timestamp.

[0078] If the LMF already has prior knowledge about the location of the anchor UE or the target UE provides location information of the anchor UE to be used as a reference, the target UE does not need to take any further action to obtain location information of the anchor UE. Two options are considered here. First, the LMF may instruct the anchor UE to perform UE-based positioning and report its location information. Second, the LMF may attempt to estimate the location of the anchor UE. For example, the LMF may attempt to estimate the location of the anchor UE based on a RAT-independent or RAT-dependent technique using DL PRS and / or UL SRS.

[0079] The LMF may instruct the anchor UE to measure the DL PRS and transmit the SL PRS within a specific (short) time period that takes into account the mobility of the target UE. To this end, the LMF may configure the anchor UE with a threshold for the time difference between DL PRS reception and SL PRS transmission. In other words, the LMF may instruct the measurement behavior of the anchor UE, i.e., the anchor UE may measure the DL PRS and transmit the SL PRS within the configured time gap instructed by the threshold.

[0080] FIG. 3 illustrates a signaling diagram according to an exemplary embodiment.

[0081] 3, in block 301, the LMF transmits assistance data including DL PRS resource configuration to a target UE. The target UE may be involved in a SL-TDOA positioning session with one or more anchor UEs. The LMF may be referred to as a network element of a core network.

[0082] The LMF may provide the reference information to the target UE through higher layer signaling, for example, "dl-PRS-ReferenceInfo-r16" of the LTE positioning protocol (LPP). Based on the current LPP structure, the LMF may provide the cell ID, TRP ID, PRS resource set ID, and PRS resource ID.

[0083] Alternatively or additionally, the target UE and / or one or more anchor UEs may be configured by sidelink positioning reference signals (SL PRS) by the gNB and / or LMF. The target UE and / or one or more anchor UEs may be configured by candidate time-frequency resources for transmission and reception of sidelink positioning reference signals by the gNB and / or LMF.

[0084] At block 302, the target UE sends a capability report to the LMF. The capability report indicates at least whether the target UE supports sidelink positioning.

[0085] In block 303, the LMF sends an instruction to the target UE to use one or more references for SL-TDOA based on one or more allowed synchronization resources and / or one or more disallowed synchronization resources.

[0086] In other words, the LMF may indicate one or more allowed synchronization resources for reference for RSTD measurements, and anchor UEs that use the one or more allowed synchronization resources may be considered as candidates for RSTD measurements.

[0087] Alternatively or additionally, the LMF may indicate one or more synchronization resources that are not allowed for reference, and anchor UEs using these synchronization resources may not be considered as candidates for RSTD measurements.

[0088] For example, the LMF may indicate that an anchor UE using a gNB as a synchronization resource is allowed as a candidate for referencing, but an anchor UE using a global navigation satellite system (GNSS) as a synchronization resource is not allowed as a candidate for referencing.

[0089] The LMF may indicate whether the target UE should use a single reference or multiple references to measure RSTD.

[0090] At block 304, the target UE reports identifiers of one or more anchor UEs as candidates for reference for SL-TDOA to the LMF. In other words, the target UE reports identifiers of one or more candidate UEs to the LMF. The one or more candidate UEs may be synchronized to one synchronization resource of one or more allowed synchronization resources. The one or more candidate UEs may not be synchronized to one or more disallowed synchronization resources. The one or more candidate UEs may be anchor UEs (or supporting UEs or auxiliary UEs) used for SL positioning. The one or more candidate UEs may be referred to herein as one or more candidate user devices.

[0091] In block 305, based on the identifiers of one or more candidate UEs, the LMF sends a request for positioning measurement reporting to one or more candidate UEs, and the LMF configures one or more candidate UEs with a threshold for the time difference between the timestamp for DL ​​PRS reception and the timestamp for SL PRS transmission. For example, the time difference may be defined as (timestamp #1 for DL ​​PRS reception) - (timestamp #2 for SL PRS transmission) < the configured threshold. In other words, a given anchor UE may measure the DL PRS and transmit the SL PRS within the configured time gap indicated by the threshold.

[0092] At block 306, the gNB (or a TRP connected to the gNB) transmits the DL PRS to the target UE and to one or more candidate UEs. Alternatively, the target UE and one or more candidate UEs may receive the DL PRS from different gNBs or TRPs.

[0093] At block 307, one or more candidate UEs transmit a SL PRS to the target UE.

[0094] At block 308, based on the request for positioning measurement reporting, one or more candidate UEs measure and report their DL positioning measurements based on the DL PRS received by the given anchor UE from the gNB (or TRP) to the LMF.

[0095] At block 309, the target UE determines or selects at least one anchor UE from the one or more candidate UEs as a reference for RSTD measurements.

[0096] At block 310, the target UE measures RSTD between at least two reference signals, where the at least two reference signals include at least SL PRS received from at least one anchor UE selected as a reference. The at least two reference signals may further include at least one DL PRS received from a network element of the radio access network (e.g., a gNB or a TRP) or an SL PRS received from another UE. In other words, the target UE may measure RSTD from specific DL PRS resources and SL PRS resources, or from two SL PRS resources from different anchor UEs.

[0097] In block 311, the target UE reports the measured RSTD and reference information for the measured RSTD to the LMF, for example, via the LTE Positioning Protocol (LPP). The reference information includes at least one of an identifier of at least one anchor UE selected as a reference, an identifier of a resource associated with an SL PRS transmitted from the at least one anchor UE, synchronization resource information of the at least one anchor UE, and / or a timestamp of the SL PRS transmitted by the at least one anchor UE. The target UE may report a timestamp for the RSTD measurement. The measured RSTD and reference information may be reported in the same report or may be reported separately.

[0098] The synchronization resource information indicates at least one synchronization resource used by the at least one anchor UE. For example, the synchronization resource information may indicate at least one of an access node such as a gNB, an NR cell ID (NCI), a physical cell identity, a physical cell identity and synchronization signal block (SSB) identity, a physical cell identity and a transmit and receive point (TRP) identity, or a global navigation satellite system (GNSS).

[0099] The timestamp of the SL PRS received from the at least one anchor UE may indicate the reception time of the SL PRS at the target UE or the transmission time of the SL PRS at the at least one anchor UE to be used as a reference.

[0100] The reference information may further include the location of at least one anchor UE at a timestamp (ie, the location at the time indicated by the timestamp) if the location is known by the target UE.

[0101] If RSTD is measured between a DL PRS and a SL PRS, the report may indicate that the reference is valid for the DL PRS and the SL PRS. If RSTD is measured between two SL PRS, the report may indicate that the reference is valid for the SL PRS.

[0102] At block 312, the LMF estimates the location of the target UE based on RSTD measurements collected from the target UE and / or DL ​​positioning measurements provided by at least one anchor UE.

[0103] If the target UE uses a single RSTD reference, the LMF may perform the location estimation algorithm using the single reference.

[0104] If the UE uses multiple RSTD references, the LMF may need to run the location estimation algorithm multiple times with different references.

[0105] 4 shows a signaling diagram according to an exemplary embodiment. In this exemplary embodiment, the target UE may propose a timestamp for the anchor UE to measure the DL PRS or transmit the SL PRS at a specific time in the future. Based on the proposal from the target UE, the LMF may request the anchor UE to measure the DL PRS and / or transmit the SL PRS at a specific time in the future.

[0106] 4, in block 401, the LMF transmits assistance data including DL PRS resource configuration to a target UE. The target UE may be involved in a SL-TDOA positioning session with one or more anchor UEs. The LMF may be referred to as a network element of a core network.

[0107] The LMF may provide the reference information to the target UE through higher layer signaling, for example, LTE Positioning Protocol (LPP) "dl-PRS-ReferenceInfo-r16". Based on the current LPP structure, the LMF may provide the cell ID, TRP ID, PRS resource set ID, and PRS resource ID.

[0108] Alternatively or additionally, the target UE and / or one or more anchor UEs may be configured by sidelink positioning reference signals (SL PRS) by the gNB and / or LMF. The target UE and / or one or more anchor UEs may be configured by candidate time-frequency resources for transmission and reception of sidelink positioning reference signals by the gNB and / or LMF.

[0109] At block 402, the target UE sends a capability report to the LMF. The capability report indicates at least whether the target UE supports sidelink positioning.

[0110] In block 403, the LMF sends an instruction to the target UE to use one or more references included in the candidate UE of one or more granted synchronization resources for SL-TDOA.

[0111] In other words, the LMF may indicate one or more allowed synchronization resources for reference for RSTD measurements, and anchor UEs that use the one or more allowed synchronization resources may be considered as candidates for RSTD measurements.

[0112] Alternatively or additionally, the LMF may indicate one or more synchronization resources that are not allowed for reference, and anchor UEs using these synchronization resources may not be considered as candidates for RSTD measurements.

[0113] For example, the LMF may indicate that an anchor UE using a gNB as a synchronization resource is allowed as a candidate for reference, but an anchor UE using a GNSS as a synchronization resource is not allowed as a candidate for reference.

[0114] The LMF may indicate whether the target UE should use a single reference or multiple references to measure RSTD.

[0115] At block 404, the target UE reports identifiers of one or more anchor UEs as candidates for reference for SL-TDOA to the LMF. In other words, the target UE reports identifiers of one or more candidate UEs to the LMF. The one or more candidate UEs may be synchronized to one synchronization resource of one or more allowed synchronization resources. The one or more candidate UEs may not be synchronized to one or more disallowed synchronization resources. The one or more candidate UEs may be anchor UEs (or supporting UEs or auxiliary UEs) used for SL positioning. The one or more candidate UEs may be referred to herein as one or more candidate user devices.

[0116] The target UE may send one or more proposed future timestamps to the LMF to measure DL PRS at or transmit SL PRS from one or more candidate UEs. Alternatively, the target UE may send one or more proposed future timestamps directly to one or more candidate UEs via the sidelink.

[0117] In block 405, based on the identifiers of one or more candidate UEs, the LMF sends a request for positioning measurement reporting to one or more candidate UEs, and the LMF configures one or more candidate UEs with a threshold for the time difference between the timestamp for DL ​​PRS reception and the timestamp for SL PRS transmission. For example, the time difference may be defined as (timestamp #1 for DL ​​PRS reception) - (timestamp #2 for SL PRS transmission) < configured threshold. In other words, a given anchor UE may measure the DL PRS and transmit the SL PRS within the configured time gap.

[0118] The LMF may provide one or more candidate UEs with one or more specific timestamps to measure DL PRS or transmit SL PRS at the timestamps. The one or more specific timestamps may be based on one or more proposed future timestamps provided by the target UE. For example, the LMF may request one or more candidate UEs to measure DL PRS or transmit SL PRS at one or more proposed future timestamps.

[0119] At block 406, the gNB (or a TRP connected to the gNB) transmits the DL PRS to the target UE and to one or more candidate UEs. Alternatively, the target UE and one or more candidate UEs may receive the DL PRS from different gNBs or TRPs.

[0120] The one or more candidate UEs transmit the SL PRS to the target UE at block 407. The one or more candidate UEs may measure the DL PRS or transmit the SL PRS at a time indicated by at least one timestamp of the one or more timestamps requested by the LMF (or suggested by the target UE).

[0121] At block 408, based on the request for positioning measurement reporting, one or more candidate UEs measure and report their DL positioning measurements based on the DL PRS received by the given anchor UE from the gNB (or TRP) to the LMF.

[0122] At block 409, the target UE determines or selects at least one anchor UE from the one or more candidate UEs as a reference for RSTD measurements.

[0123] At block 410, the target UE measures RSTD between at least two reference signals, where the at least two reference signals include at least SL PRS received from at least one anchor UE selected as a reference. The at least two reference signals may further include at least one DL PRS received from a network element of the radio access network (e.g., a gNB or a TRP) or an SL PRS received from another UE. In other words, the target UE may measure RSTD from specific DL PRS resources and SL PRS resources, or from two SL PRS resources from different anchor UEs.

[0124] In block 411, the target UE reports the measured RSTD and reference information for the measured RSTD to the LMF, for example, via LPP. The reference information includes at least one of an identifier of at least one anchor UE selected as a reference, an identifier of a resource associated with an SL PRS transmitted from the at least one anchor UE, synchronization resource information of the at least one anchor UE, and / or a timestamp of an SL PRS transmitted by the at least one anchor UE. The target UE may report a timestamp for the RSTD measurement. The measured RSTD and reference information may be reported in the same report or may be reported separately.

[0125] The synchronization resource information indicates at least one synchronization resource used by the at least one anchor UE. For example, the synchronization resource information may indicate at least one of an access node such as a gNB, an NR cell ID (NCI), a physical cell identity, a physical cell identity and SSB identity, a physical cell identity and TRP identity, or a GNSS.

[0126] The timestamp of the SL PRS received from the at least one anchor UE may indicate the reception time of the SL PRS at the target UE or the transmission time of the SL PRS at the at least one anchor UE to be used as a reference.

[0127] The reference information may further include the location of at least one anchor UE at a timestamp (ie, the location at the time indicated by the timestamp) if the location is known by the target UE.

[0128] If RSTD is measured between a DL PRS and a SL PRS, the report may indicate that the reference is valid for the DL PRS and the SL PRS. If RSTD is measured between two SL PRS, the report may indicate that the reference is valid for the SL PRS.

[0129] At block 412, the LMF estimates the location of the target UE based on RSTD measurements collected from the target UE and / or DL ​​positioning measurements provided by at least one anchor UE.

[0130] If the target UE uses a single RSTD reference, the LMF may perform the location estimation algorithm using the single reference.

[0131] If the UE uses multiple RSTD references, the LMF may need to run the location estimation algorithm multiple times with different references.

[0132] 5 shows a signaling diagram according to an exemplary embodiment, in which the LMF requests the anchor UE to report its location at a specific timing based on UE-based positioning using RAT-dependent or RAT-independent techniques.

[0133] 5, in block 501, an LMF transmits assistance data including a DL PRS resource configuration to a target UE. The target UE may be involved in an SL-TDOA positioning session with one or more anchor UEs. The LMF may be referred to as a network element of a core network.

[0134] The LMF may provide the reference information to the target UE through higher layer signaling, for example, LTE Positioning Protocol (LPP) "dl-PRS-ReferenceInfo-r16". Based on the current LPP structure, the LMF may provide the cell ID, TRP ID, PRS resource set ID, and PRS resource ID.

[0135] Alternatively or additionally, the target UE and / or one or more anchor UEs may be configured by sidelink positioning reference signals (SL PRS) by the gNB and / or LMF. The target UE and / or one or more anchor UEs may be configured by candidate time-frequency resources for transmission and reception of sidelink positioning reference signals by the gNB and / or LMF.

[0136] At block 502, the target UE sends a capability report to the LMF. The capability report indicates at least whether the target UE supports sidelink positioning.

[0137] In block 503, the LMF sends an instruction to the target UE to use one or more references included in the candidate UE of one or more granted synchronization resources for SL-TDOA.

[0138] In other words, the LMF may indicate one or more allowed synchronization resources for reference for RSTD measurements, and anchor UEs that use the one or more allowed synchronization resources may be considered as candidates for RSTD measurements.

[0139] Alternatively or additionally, the LMF may indicate one or more synchronization resources that are not allowed for reference, and anchor UEs using these synchronization resources may not be considered as candidates for RSTD measurements.

[0140] For example, the LMF may indicate that an anchor UE using a gNB as a synchronization resource is allowed as a candidate for reference, but an anchor UE using a GNSS as a synchronization resource is not allowed as a candidate for reference.

[0141] The LMF may indicate whether the target UE should use a single reference or multiple references to measure RSTD.

[0142] At block 504, the target UE reports identifiers of one or more anchor UEs as candidates for reference for SL-TDOA to the LMF. In other words, the target UE reports identifiers of one or more candidate UEs to the LMF. The one or more candidate UEs may be synchronized to one synchronization resource of one or more allowed synchronization resources. The one or more candidate UEs may not be synchronized to one or more disallowed synchronization resources. The one or more candidate UEs may be anchor UEs (or supporting UEs or auxiliary UEs) used for SL positioning. The one or more candidate UEs may be referred to herein as one or more candidate user devices.

[0143] In block 505, based on the identifiers of the one or more candidate UEs, the LMF measures the DL PRS at one or more specific timestamps and sends a request to the one or more candidate UEs to report corresponding location information of the one or more candidate UEs to the LMF.

[0144] At block 506, the LMF sends a request to the target UE to report RSTD measurements taken at one or more specific timestamps, where the one or more specific timestamps indicated to the target UE may be the same as the one or more specific timestamps indicated to the one or more candidate UEs.

[0145] At block 507, the gNB (or a TRP connected to the gNB) transmits the DL PRS to the target UE and to one or more candidate UEs. Alternatively, the target UE and one or more candidate UEs may receive the DL PRS from different gNBs or TRPs.

[0146] At block 508, one or more candidate UEs transmit a SL PRS to the target UE.

[0147] Based on the request to report location information, one or more candidate UEs report their location information and corresponding timestamps to the LMF in block 509. The location information indicates the location of the given candidate UE at the corresponding timestamp.

[0148] At block 510, the target UE determines or selects at least one anchor UE from the one or more candidate UEs as a reference for RSTD measurements.

[0149] In block 511, the target UE measures RSTD between at least two reference signals, where the at least two reference signals include at least SL PRS received from at least one anchor UE selected as a reference. The at least two reference signals may further include at least one DL PRS received from a network element of the radio access network (e.g., a gNB or a TRP) or an SL PRS received from another UE. In other words, the target UE may measure RSTD from specific DL PRS resources and SL PRS resources, or from two SL PRS resources from different anchor UEs. The measurements are performed at one or more specific timestamps indicated by the LMF.

[0150] At block 512, the target UE reports the measured RSTD and reference information for the measured RSTD to the LMF, for example, via LPP. The reference information includes at least one of an identifier of at least one anchor UE selected as a reference, an identifier of a resource associated with an SL PRS transmitted from the at least one anchor UE, synchronization resource information of the at least one anchor UE, and / or a timestamp of the SL PRS transmitted by the at least one anchor UE. The target UE may report a timestamp of the RSTD measurement. The measured RSTD and reference information may be reported in the same report or may be reported separately.

[0151] The synchronization resource information indicates at least one synchronization resource used by the at least one anchor UE. For example, the synchronization resource information may indicate at least one of an access node such as a gNB, an NR cell ID (NCI), a physical cell identity, a physical cell identity and SSB identity, a physical cell identity and TRP identity, or a GNSS.

[0152] The timestamp of the SL PRS received from the at least one anchor UE may indicate the reception time of the SL PRS at the target UE or the transmission time of the SL PRS at the at least one anchor UE to be used as a reference.

[0153] If RSTD is measured between a DL PRS and a SL PRS, the report may indicate that the reference is valid for the DL PRS and the SL PRS. If RSTD is measured between two SL PRS, the report may indicate that the reference is valid for the SL PRS.

[0154] At block 513, the LMF estimates the location of the target UE based on RSTD measurements collected from the target UE and / or location information provided by at least one anchor UE.

[0155] If the target UE uses a single RSTD reference, the LMF may perform the location estimation algorithm using the single reference.

[0156] If the UE uses multiple RSTD references, the LMF may need to run the location estimation algorithm multiple times with different references.

[0157] 6 shows a flowchart according to an example embodiment of a method implemented by an apparatus such as, comprising, or included in a user device in a radio access network. The user device may also be referred to as a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, user equipment (UE), target UE, or target user device. The user device may correspond to user device 100 of FIG. 1.

[0158] Referring to FIG. 6, at block 601, at least one user device is selected from one or more candidate user devices as a reference for reference signal time difference (RSTD) measurements.

[0159] In block 602, the RSTD is measured between at least two reference signals, the at least two reference signals including at least a sidelink positioning reference signal (SL PRS) received from at least one user device selected as a reference. For example, the at least two reference signals may further include at least one of a downlink positioning reference signal received from a network element of a radio access network or a sidelink reference signal received from another user device.

[0160] In block 603, a report is sent to a network element (e.g., LMF) of the core network, the report including at least one of an identifier of at least one user device selected as a reference for RSTD measurements, an identifier of a resource associated with a sidelink positioning reference signal received from the at least one user device, synchronization resource information indicating at least one synchronization resource of the at least one user device, or a timestamp of a sidelink positioning reference signal received from the at least one user device.

[0161] The apparatus may further transmit a measurement report to a network element of the core network indicating the measured RSTD associated with at least one user device selected as a reference for the RSTD measurement. The measurement report may be transmitted together with or separately from the above-mentioned report.

[0162] 7 shows a flowchart according to an example embodiment of a method performed by an apparatus such as, comprising, or included in a network element of a core network. The network element may correspond to the LMF 112 of FIG. 1.

[0163] Referring to FIG. 7, in block 701, a report is received from a target user device, the report including at least one of: an identifier of at least one user device selected as a reference for measuring a reference signal time difference (RSTD); an identifier of a resource associated with a sidelink positioning reference signal (SL PRS) used to measure the RSTD; synchronization resource information indicating at least one synchronization resource of the at least one user device selected as a reference for measuring the RSTD; or a timestamp of a sidelink positioning reference signal used to measure the RSTD.

[0164] At block 702, a location of the target user device is estimated based at least in part on the report.

[0165] The apparatus may further receive a measurement report from the target user device indicating a measured RSTD associated with at least one user device selected as a reference for the RSTD measurement, and the location of the target user device may be estimated based at least in part on the measured RSTD. The measurement report may be received together with or separately from the report mentioned above.

[0166] 8 shows a flowchart according to an example embodiment of a method implemented by an apparatus such as, comprising, or included in a user device in a radio access network. The user device may also be referred to as a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, user equipment (UE), anchor UE, or anchor user device. The user device may correspond to the user device 102 of FIG. 1.

[0167] Referring to FIG. 8, in block 801, a threshold is received from a network element (e.g., LMF) of a core network, the threshold being for a time difference between receiving a downlink positioning reference signal (DL PRS) and transmitting a sidelink positioning reference signal (SL PRS).

[0168] At block 802, a sidelink positioning reference signal is transmitted to the target user device based on at least a threshold, wherein a time difference between receiving the downlink positioning reference signal and transmitting the sidelink positioning reference signal is less than the threshold.

[0169] The blocks, associated functions, and information exchanges (messages) described above with reference to Figures 3-8 are not in absolute chronological order, and some of them may be performed simultaneously or in a different order than described. Other functions may be performed between or among them as well, other information may be sent, and / or other rules may apply. Some of the blocks, or portions of the blocks, or one or more pieces of information may also be omitted or replaced by a corresponding block, portion of the block, or one or more pieces of information.

[0170] As used herein, "at least one of the following: <list of two or more elements>" )" and "at least one of <list of two or more elements>" )" and similar phrases where a list of two or more elements is joined by "and" or "or" mean at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0171] In some exemplary embodiments, the UE may be instructed by the network that a DL PRS resource can be used as a reference for DL ​​RSTD, DL PRS-RSRP, and UE Rx-Tx time difference measurements in the higher layer parameter nr-DL-PRS-ReferenceInfo. The reference indicated to the UE by the network can also be used by the UE to determine how to apply the higher layer parameters nr-DL-PRS-ExpectedRSTD and nr-DL-PRS-ExpectedRSTD-Uncertainty. The UE expects the reference to be indicated whenever it expects to receive a DL PRS. This reference provided by nr-DL-PRS-ReferenceInfo may include a dl-PRS-ID, a DL PRS resource set ID, and optionally, a single DL PRS resource ID or a list of DL PRS resource IDs. The UE may use different DL PRS resources or different DL PRS resource sets to determine the reference for RSTD measurements while the condition that the used DL PRS resource belongs to a single DL PRS resource set is met. If the UE chooses to use a different reference than that indicated by the network, it is expected to report the dl-PRS-ID, DL PRS resource ID, or DL ​​PRS resource set ID used to determine the reference. For the reported reference, the UE may report whether this reference is valid only for DL ​​PRSs or whether this reference is valid for DL ​​PRSs and SL PRSs as well for RSTD measurements. If the UE chooses to use a different reference than that indicated by the network, it is expected to report the UE ID, SL PRS resource ID, UE synchronization resource information, and the timestamp of the transmitted SL PRS resource ID.If the report does not include reference information for RSTD measurements from SL and DL PRS resources, the network may prioritize nr-DL-PRS-ReferenceInfo to assume the reference for RSTD measurements. The UE may be instructed by the network to use a single RSTD reference from SL PRS resources with a specific synchronization resource, and the UE may be expected to report the used RSTD reference.

[0172] A further consideration is that the UE may report an RSTD reference, but the reported RSTD reference may not be the reference for the reported RSTD measurement. For example, the UE may report TRP#1 and UE#1 as the reference for the RSTD measurement. If the UE is permitted by the network to report RSTD from TRP#2 and UE#2, there may be a rule for the LMF to assume what the reference for the reported RSTD measurement is. In this case, one option is for the LMF to assume the DL PRS instead of the SL PRS as the RSTD reference.

[0173] In some example embodiments, if the LMF does not have proper knowledge about the anchor UE, it may only configure the current reference configuration (reference configuration for DL-PRS). However, the target UE may still use the SL-UE as the SL-TDOA reference, and the target UE may replace the configured current reference with the SL-UE / SL-PRS for SL-TDOA.

[0174] The target UE may be allowed to use and report multiple references. For example, the LMF may allow the use of multiple RSTD references if it supports running separate location estimation algorithms, such as least squares (LS), for a given reference. The target UE may then have more flexibility for reporting RSTD measurements. For example, the UE may select one TRP and one anchor UE as the reference, or the UE may select two different anchor UEs as the reference. Furthermore, even if the target UE selects two references, the LMF may perform further calculations to effectively use a single reference. If the UE reports a specific TRP as the DL-TDOA reference and the UE reports an SL-UE as the SL-TDOA reference, but the TRP is within the gNB, the SL-UE may be synchronized to the same gNB.

[0175] 9 illustrates an example of an apparatus 900 in a radio access network, an apparatus comprising means for performing the method of FIG. 6, the method of FIG. 8, or any other exemplary embodiment described above. For example, the apparatus 900 may be an apparatus such as, comprising, or included in a user device. The user device may correspond to one of the user devices 100, 102 of FIG. 1. The user device may also be referred to as a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, a terminal device, user equipment (UE), an anchor UE, a target UE, or a target user device.

[0176] The device 900 comprises at least one processor 910. The at least one processor 910 interprets computer program instructions and processes data. The at least one processor 910 may comprise one or more programmable processors. The at least one processor 910 may comprise programmable hardware with embedded firmware, or alternatively or additionally, may comprise one or more application-specific integrated circuits (ASICs).

[0177] The at least one processor 910 is coupled to the at least one memory 920. The at least one processor is configured to write / read data to / from the at least one memory 920. The at least one memory 920 may comprise one or more memory units. The memory units may be volatile or nonvolatile. It is noted that there may be one or more memory units of nonvolatile memory and one or more memory units of volatile memory, or alternatively, one or more memory units of nonvolatile memory, or alternatively, one or more memory units of volatile memory. The volatile memory may be, for example, random access memory (RAM), dynamic random access memory (DRAM), or synchronous dynamic random access memory (SDRAM). The nonvolatile memory may be, for example, read-only memory (ROM), programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), flash memory, optical storage, or magnetic storage. In general, memory may be referred to as a non-transitory computer-readable medium. The term "non-transitory," as used herein, refers to a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation regarding data storage persistence (e.g., RAM vs. ROM). At least one memory 920 stores computer-readable instructions, which are executed by at least one processor 910 to implement one or more of the exemplary embodiments described above. For example, a non-volatile memory stores the computer-readable instructions, and the at least one processor 910 executes the instructions using a volatile memory for temporary storage of data and / or instructions. The computer-readable instructions may also be referred to as computer program code.

[0178] The computer-readable instructions may be pre-stored in at least one memory 920, or alternatively or additionally, the computer-readable instructions may be received by the apparatus via an electromagnetic carrier signal and / or copied from a physical entity such as a computer program product. Execution of the computer-readable instructions by the at least one processor 910 causes the apparatus 900 to implement one or more of the exemplary embodiments described above. That is, the at least one processor and at least one memory storing instructions may provide a means for providing or effecting the performance of any of the methods and / or blocks described above.

[0179] In the context of this document, "memory" or "computer-readable media" or "computer-readable medium" may be any non-transitory medium or vehicle or means that can contain, store, communicate, propagate, or transport instructions for use by or in connection with an instruction execution system, apparatus, or device such as a computer. The term "non-transitory," as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation regarding data storage persistence (e.g., RAM vs. ROM).

[0180] The device 900 may further include or be connected to an input unit 930. The input unit 930 may include one or more interfaces for receiving input. The one or more interfaces may include, for example, one or more temperature, motion, and / or orientation sensors, one or more cameras, one or more accelerometers, one or more microphones, one or more buttons, and / or one or more touch detection units. Additionally, the input unit 930 may include an interface to which external devices may connect.

[0181] The device 900 may comprise an output unit 940. The output unit may comprise or be connected to one or more displays capable of rendering visual content, such as a light emitting diode (LED) display, a liquid crystal display (LCD), and / or a liquid crystal on silicon (LCoS) display. The output unit 940 may further comprise one or more audio outputs. The one or more audio outputs may be, for example, loudspeakers.

[0182] The device 900 further comprises a connectivity unit 950. The connectivity unit 950 enables wireless connectivity to one or more external devices. The connectivity unit 950 comprises at least one transmitter and at least one receiver, which may be integrated into the device 900 or to which the device 900 may be connected. The at least one transmitter comprises at least one transmit antenna, and the at least one receiver comprises at least one receive antenna. The connectivity unit 950 may comprise an integrated circuit or a set of integrated circuits that provide wireless communication capabilities for the device 900. Alternatively, the wireless connectivity may be a hardwired application-specific integrated circuit (ASIC). The connectivity unit 950 may comprise one or more components, such as a power amplifier, a digital front end (DFE), an analog-to-digital converter (ADC), a digital-to-analog converter (DAC), a frequency converter, a (de)modulator, and / or encoder / decoder circuitry, controlled by a corresponding control unit.

[0183] It is noted that the apparatus 900 may further comprise various components not shown in Figure 9. The various components may be hardware components and / or software components.

[0184] 10 illustrates an example of an apparatus 1000 in a core network, an apparatus comprising means for performing the method of FIG. 7, or any other exemplary embodiment described above. For example, the apparatus 1000 may be an apparatus such as, comprising, or included in a network element of the core network. The network element may correspond to the LMF 112 of FIG. 1. The network element may be referred to, for example, as a network node or a location server.

[0185] The apparatus 1000 may include, for example, circuitry or a chipset applicable to implementing one or more of the exemplary embodiments described above. The apparatus 1000 may also be an electronic device including one or more electronic circuitry. The apparatus 1000 may include communication control circuitry 1010, such as at least one processor, and at least one memory 1020 storing instructions that, when executed by the at least one processor, cause the apparatus 1000 to implement one or more of the exemplary embodiments described above. Such instructions may include, for example, computer program code (software) 1022, where the at least one memory and the computer program code (software) 1022 are configured to, with the at least one processor, cause the apparatus 1000 to implement one or more of the exemplary embodiments described above. Herein, computer program code may then refer to instructions that, when executed by the at least one processor, cause the apparatus 1000 to implement one or more of the exemplary embodiments described above. That is, at least one processor and at least one memory storing instructions may provide the means for providing or effecting the performance of any of the methods and / or blocks described above.

[0186] The processor is coupled to the memory 1020. The processor is configured to write / read data to / from the memory 1020. The memory 1020 may comprise one or more memory units. The memory units may be volatile or nonvolatile. It is noted that there may be one or more units of nonvolatile memory and one or more units of volatile memory, or alternatively, one or more units of nonvolatile memory, or alternatively, one or more units of volatile memory. The volatile memory may be, for example, random access memory (RAM), dynamic random access memory (DRAM), or synchronous dynamic random access memory (SDRAM). The nonvolatile memory may be, for example, read-only memory (ROM), programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), flash memory, optical storage, or magnetic storage. In general, memory may be referred to as a non-transitory computer-readable medium. The term "non-transitory," as used herein, refers to a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation regarding data storage persistence (e.g., RAM versus ROM). The memory 1020 stores computer-readable instructions that are executed by the processor. For example, non-volatile memory stores computer-readable instructions, and the processor executes the instructions using volatile memory for temporary storage of data and / or instructions.

[0187] The computer-readable instructions may be pre-stored in memory 1020, or alternatively or additionally, the computer-readable instructions may be received by the device via an electromagnetic carrier signal and / or copied from a physical entity such as a computer program product. Execution of the computer-readable instructions causes the device 1000 to perform one or more of the functions described above.

[0188] The memory 1020 may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and / or removable memory. The memory may comprise a configuration database for storing configuration data. For example, the configuration database may store a current neighbor cell list and, in some exemplary embodiments, the frame structure used in detected neighbor cells.

[0189] The device 1000 may further comprise a communication interface 1030 comprising hardware and / or software for providing communication connectivity according to one or more communication protocols. The communication interface 1030 comprises at least one transmitter (Tx) and at least one receiver (Rx), which may be integrated into the device 1000 or to which the device 1000 may be connected. The communication interface 1030 may comprise one or more components, such as a power amplifier, a digital front end (DFE), an analog-to-digital converter (ADC), a digital-to-analog converter (DAC), a frequency converter, a (de)modulator, and / or encoder / decoder circuitry, controlled by a corresponding control unit.

[0190] The communication interface 1030 provides the device with wireless communication capabilities for communicating in a cellular communication system. The communication interface may, for example, provide a radio interface to one or more user devices. The device 1000 may further comprise another interface towards a core network, such as a network coordinator device or AMF, and / or to an access node of the cellular communication system.

[0191] It is noted that the apparatus 1000 may further comprise various components not shown in Figure 10. The various components may be hardware components and / or software components.

[0192] As used in this application, the term "circuitry" may refer to one or more or all of the following: a) hardware-only circuit implementations (such as implementations with only analog and / or digital circuitry), and b) combinations of hardware circuitry and software, for example, (where applicable): i) combinations of analog hardware circuitry and / or digital hardware circuitry with software / firmware, and ii) any portion of a hardware processor with software (including digital signal processors, software, and memory that work together to cause a device such as a mobile phone to perform various functions), and c) hardware circuitry and / or processors, such as a microprocessor or portion of a microprocessor, that require software (e.g., firmware) to operate, but the software may be absent when not required for operation.

[0193] This definition of circuitry applies to all uses of the term in this application, including in any claim. As a further example, as used in this application, the term circuitry also covers merely a hardware circuit or processor (or processors), or certain portions of a hardware circuit or processor and its (or their) associated software and / or firmware implementations. The term circuitry also covers, for example, a baseband integrated circuit, or a processor integrated circuit for a mobile device, or similar integrated circuit in a server, cellular network device, or other computing or network device, if applicable to particular claim elements.

[0194] The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or a combination thereof. In a hardware implementation, the apparatus of the exemplary embodiments may be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), graphics processing units (GPUs), processors, controllers, microcontrollers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. In a firmware or software implementation, the implementation may be implemented through modules (e.g., procedures, functions, etc.) of at least one chipset that perform the functions described herein. Software code may be stored in a memory unit and executed by a processor. The memory unit may execute within the processor or external to the processor. In the latter case, the memory unit may be communicatively coupled to the processor by various means, as is known in the art. Furthermore, the components of the systems described herein may be rearranged and / or supplemented by additional components to facilitate accomplishing various aspects, etc., described with respect to the components, and the components are not limited to the precise configurations set forth in the given figures, as will be recognized by those skilled in the art.

[0195] It will be obvious to those skilled in the art that as technology advances, the concept of the present invention may be implemented in various ways. The embodiments are not limited to the exemplary embodiments described above, but may vary within the scope of the claims. Therefore, all words and expressions should be interpreted broadly and are intended to illustrate, not limit, exemplary embodiments.

Claims

1. 1. An apparatus in a radio access network, comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform at least: selecting at least one user device from the one or more candidate user devices as a reference for a reference signal time difference (RSTD) measurement; measuring an RSTD between at least two reference signals, the at least two reference signals including at least a sidelink positioning reference signal received from the at least one user device selected as the reference; transmitting to a network element of a core network a report comprising an identifier of the at least one user device selected as the reference for the RSTD measurements, identifiers of resources associated with the sidelink positioning reference signals received from the at least one user device, synchronization resource information indicating at least one synchronization resource of the at least one user device, and timestamps of the sidelink positioning reference signals received from the at least one user device. A device that performs the following.

2. 2. The apparatus of claim 1, further configured to transmit, to the network element of the core network, a measurement report indicating the measured RSTD associated with the at least one user device selected as the reference for the RSTD measurement.

3. 2. The apparatus of claim 1, wherein the at least two reference signals further comprise at least one of a downlink positioning reference signal received from a network element of the radio access network or a sidelink reference signal received from another user device.

4. 4. The apparatus of claim 3, wherein the report indicates that the reference is to be used for measuring the RSTD between the downlink positioning reference signal and the sidelink positioning reference signal received from the at least one user device selected as the reference.

5. 10. The apparatus of claim 1, wherein the synchronization resource information indicates at least one of an access node, a cell identity, a physical cell identity, the physical cell identity and a synchronization signal block identity, the physical cell identity and a transmitting and receiving point identity, or a global navigation satellite system.

6. 2. The apparatus of claim 1, wherein the timestamp of the sidelink positioning reference signal received from the at least one user device indicates a time of reception of the sidelink positioning reference signal at the apparatus.

7. The apparatus of claim 1 , wherein the report further includes a location of the at least one user device at the timestamp, the at least one user device being selected as the reference.

8. further configured to receive an indication from the network element of the core network indicating one or more allowed synchronization resources for the reference; The apparatus of claim 1 , wherein the one or more candidate user devices are synchronized to at least one of the one or more allowed synchronization resources.

9. further configured to receive an indication from the network element of the core network indicating one or more synchronization resources that are not allowed for the reference; The apparatus of claim 1 , wherein the one or more candidate user devices are not synchronized to the one or more synchronization resources that are not permitted.

10. 2. The apparatus of claim 1, further configured to transmit to the at least one user device or to the network element of the core network one or more proposed timestamps for measuring a downlink positioning reference signal at the at least one user device or transmitting the sidelink positioning reference signal from the at least one user device.

11. The apparatus of claim 1 , further adapted to report identifiers of the one or more candidate user devices to the network element of the core network.

12. further configured to receive, from the network element of the core network, an indication to use a single reference for measuring the RSTD; The apparatus of claim 1 , wherein the at least one user device is selected based at least in part on the indication to use the single reference, and the at least one user device comprises a single user device.

13. further receiving an indication from the network element of the core network to use multiple references to measure the RSTD; The apparatus of claim 1 , wherein the at least one user device is selected based at least in part on the indication to use the multiple references.

14. 1. An apparatus in a core network, comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform at least: receiving from a target user device a report comprising an identifier of at least one user device selected as a reference for measuring a Reference Signal Time Difference (RSTD), an identifier of a resource associated with a sidelink positioning reference signal used to measure the RSTD, synchronization resource information indicating at least one synchronization resource of the at least one user device selected as the reference for measuring the RSTD, and a timestamp of the sidelink positioning reference signal used to measure the RSTD; estimating a location of the target user device based at least in part on the report; and A device that performs the following.

15. 15. The apparatus of claim 14, further configured to receive, from the target user device, a measurement report indicating the measured RSTD associated with the at least one user device selected as the reference for measuring the RSTD, and to estimate the location of the target user device based at least in part on the measured RSTD.

16. 15. The apparatus of claim 14, wherein the report indicates that the reference is used to measure the RSTD between a downlink positioning reference signal and the sidelink positioning reference signal.

17. 15. The apparatus of claim 14, wherein the synchronization resource information indicates at least one of an access node, a cell identity, a physical cell identity, the physical cell identity and a synchronization signal block identity, the physical cell identity and a transmitting and receiving point identity, or a global navigation satellite system.

18. 15. The apparatus of claim 14, wherein the timestamp of the sidelink positioning reference signal indicates a time of reception of the sidelink positioning reference signal at the target user device or a time of transmission of the sidelink positioning reference signal at the at least one user device.

19. The apparatus of claim 14 , wherein the report further includes a location of the at least one user device at the timestamp, the at least one user device being selected as the reference for measuring the RSTD.

20. The apparatus of claim 14 , further adapted to transmit an indication to the target user device indicating one or more allowed synchronization resources for the reference.

21. The apparatus of claim 14 , further adapted to send an indication to the target user device indicating one or more synchronization resources that are not allowed for the referencing.

22. The apparatus of claim 14 , further configured to receive, from the target user device, identifiers of one or more candidate user devices for the reference, the one or more candidate user devices comprising at least the at least one user device.

23. 23. The apparatus of claim 22, further configured to transmit to the one or more candidate user devices a threshold for a time difference between receiving a downlink positioning reference signal and transmitting the sidelink positioning reference signal based on the identifiers of the one or more candidate user devices.

24. receiving from the target user device one or more proposed timestamps for measuring downlink positioning reference signals at the one or more candidate user devices or transmitting the sidelink positioning reference signals from the one or more candidate user devices; transmitting a request to the one or more candidate user devices to measure the downlink positioning reference signal or transmit the sidelink positioning reference signal at the one or more proposed timestamps.

23. The apparatus of claim 22, further adapted to:

25. sending a request to the one or more candidate user devices to report locations and corresponding timestamps of the one or more candidate user devices; receiving, based on the request, a report from the one or more candidate user devices indicating the location and the corresponding timestamp of the one or more candidate user devices; and The apparatus of claim 22 , wherein the location of the target user device is estimated based at least in part on the location of the at least one user device included in the one or more candidate user devices.

26. 15. The apparatus of claim 14, further adapted to transmit to the target user device an instruction to use a single reference to measure the RSTD, wherein the at least one user device comprises a single user device.

27. The apparatus of claim 14 , further adapted to transmit to the target user device an instruction to use multiple references to measure the RSTD.

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