GB2632339A

GB2632339A - Method, apparatus and computer program

Info

Publication number: GB2632339A
Application number: GB2311996.9A
Authority: GB
Inventors: Keshavamurthy Prajwal; Michalopoulos Diomidis
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2023-08-04
Filing date: 2023-08-04
Publication date: 2025-02-05
Also published as: GB202311996D0; WO2025031623A1

Abstract

There is provided an apparatus comprising means for: receiving, from one or more second user equipments in a sidelink (SL) positioning session with a first user equipment, respective 5 reference user equipment selection assistance information; selecting a reference user equipment from among the one of the one or more second user equipments based on the reference user equipment selection assistance information; and sending, to the selected reference user equipment, an indication that it has been selected as the reference user equipment for the sidelink positioning session.

Description

METHOD, APPARATUS AND COMPUTER PROGRAM

FIELD

The present application relates to a method, apparatus, system and computer program and in particular but not exclusively to sidelink positioning.

BACKGROUND

A communication system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, base stations and/or other nodes by providing carriers between the various entities involved in the communications path. A communication system can be provided for example by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, video, electronic mail (email), text message, multimedia and/or content data and so on. Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.

In a wireless communication system at least a part of a communication session between at least two stations occurs over a wireless link. Examples of wireless systems comprise public land mobile networks (PLMN), satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN). Some wireless systems can be divided into cells, and are therefore often referred to as cellular systems.

A user can access the communication system by means of an appropriate communication device or terminal. A communication device of a user may be referred to as user equipment (UE) or user device. A communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other users. The communication device may access a carrier provided by a station, for example a base station of a cell, and transmit and/or receive communications on the carrier.

The communication system and associated devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and/or parameters which shall be used for the connection are also typically defined. One example of a communications system is UTRAN (3G radio). Other examples of communication systems are the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology and so-called 5G or New Radio (NR) networks. NR is being standardized by the 3rd Generation Partnership Project (3GPP).

SUMMARY

According to an aspect, there is provided an apparatus comprising means for: receiving, from one or more second user equipments in a sidelink positioning session with a first user equipment, respective reference user equipment selection assistance information; selecting a reference user equipment from among the one of the one or more second user equipments based on the reference user equipment selection assistance information; and sending, to the selected reference user equipment, an indication that it has been selected as the reference user equipment for the sidelink positioning session.

The apparatus may further comprise means for: sending, to the one or more second user equipments, a request for the reference user equipment selection assistance information, wherein the receiving the reference user equipment selection assistance information may be based on sending the request.

The apparatus may be a server user equipment or an apparatus for a location management function, and the apparatus may further comprise means for: sending, to the first user equipment, information indicating the identity of the selected reference user equipment.

The apparatus may be the first user equipment, and the apparatus may further comprise means for: receiving, from a location management function or server user equipment, configuration information indicating one or more conditions for reference user equipment selection, wherein selecting the reference user equipment may be further based on the received configuration information.

The apparatus may further comprise means for: sending, to the location management function or server user equipment, information indicating the identity of the selected reference user equipment.

The one or more conditions may comprise one or more of: tolerable ratio of uninterrupted availability of the reference user equipment over a duration of the sidelink positioning session; acceptable stability of a time reference of the reference user equipment; allowable location uncertainty of the reference user equipment; and allowable mobility status of the reference user equipment.

The reference user equipment selection assistance information may comprise one or more of: availability information of the second user equipment; synchronization information of the second user equipment; location information of the second user equipment; and mobility information of the second user equipment.

The availability information may comprise information indicating an expected availability and/or unavailability of the second user equipment to support the sidelink positioning session of the first user equipment; the synchronization information may comprise information indicating a time reference of the second user equipment; the location information may comprise information indicating a location of the second user equipment and information indicating an uncertainty of the location of the second user equipment; and the mobility information may comprise information indicating one or more of: a relative velocity of the second user equipment, a relative trajectory of the second user equipment, and a proximity of the second user equipment.

According to an aspect, there is provided an apparatus comprising means for: sending, to a first user equipment in a sidelink positioning session with one or more second user equipments, configuration information indicating one or more conditions for reference user equipment selection.

The apparatus may further comprise means for: receiving, from the first user equipment, information indicating a selected reference user equipment.

The apparatus may be one of: a server user equipment or an apparatus for a location management function.

According to an aspect there is provided a second user equipment comprising means for: sending, to an apparatus, reference user equipment selection assistance information for selecting a reference user equipment in a sidelink positioning session between a first user equipment and at least one second user equipment including the second user equipment.

The second user equipment may further comprise means for: receiving, from the apparatus, a notification that the second user equipment has been selected as the reference user equipment for the sidelink positioning session.

The second user equipment may further comprise means for: receiving, from the apparatus, a request for the reference user equipment selection assistance information, wherein the sending the reference user equipment selection assistance information may be based on receiving the request.

The apparatus may comprise one of: the first user equipment; an apparatus for a location management function; or a server user equipment.

According to an aspect, there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from one or more second user equipments in a sidelink positioning session with a first user equipment, respective reference user equipment selection assistance information; select a reference user equipment from among the one of the one or more second user equipments based on the reference user equipment selection assistance information; and send, to the selected reference user equipment, an indication that it has been selected as the reference user equipment for the sidelink positioning session.

The at least one processor may further cause the apparatus to: send, to the one or more second user equipments, a request for the reference user equipment selection assistance information, wherein the receiving the reference user equipment selection assistance information may be based on sending the request.

The apparatus may be a server user equipment or an apparatus for a location management function, and the at least one processor may further cause the apparatus to: send, to the first user equipment, information indicating the identity of the selected reference user equipment.

The apparatus may be the first user equipment, and the at least one processor may further cause the apparatus to: receive, from a location management function or server user equipment, configuration information indicating one or more conditions for reference user equipment selection, wherein the at least one processor may further cause the apparatus to select the reference user equipment based on the received configuration information.

The at least one processor may further cause the apparatus to: send, to the location management function or server user equipment, information indicating the identity of the selected reference user equipment.

The reference user equipment selection assistance information may comprises one or more of: availability information of the second user equipment; synchronization information of the second user equipment; location information of the second user equipment; and mobility information of the second user equipment.

According to an aspect, there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: send, to a first user equipment in a sidelink positioning session with one or more second user equipments, configuration information indicating one or more conditions for reference user equipment selection.

The at least one processor may further cause the apparatus to: receive, from the first user equipment, information indicating a selected reference user equipment.

According to an aspect, there is provided a second user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the second user equipment at least to: send, to an apparatus, reference user equipment selection assistance information for selecting a reference user equipment in a sidelink positioning session between a first user equipment and at least one second user equipment including the second user equipment.

The at least one processor may further cause the second user equipment to: receiving, from the apparatus, a notification that the second user equipment has been selected as the reference user equipment for the sidelink positioning session.

The at least one processor may further cause the second user equipment to: receive, from the apparatus, a request for the reference user equipment selection assistance information, wherein the at least one processor may further cause the second user equipment to send the reference user equipment selection assistance information based on receiving the request.

According to an aspect, there is provided a method comprising: receiving, from one or more second user equipments in a sidelink positioning session with a first user equipment, respective reference user equipment selection assistance information; selecting a reference user equipment from among the one of the one or more second user equipments based on the reference user equipment selection assistance information; and sending, to the selected reference user equipment, an indication that it has been selected as the reference user equipment for the sidelink positioning session.

The method may further comprise: sending, to the one or more second user equipments, a request for the reference user equipment selection assistance information, wherein the receiving the reference user equipment selection assistance information may be based on sending the request.

The method may be performed by a server user equipment or an apparatus for a location management function, and the method may further comprise: sending, to the first user equipment, information indicating the identity of the selected reference user equipment.

The method may be performed by the first user equipment, and the method may further comprise: receiving, from a location management function or server user equipment, configuration information indicating one or more conditions for reference user equipment selection, wherein selecting the reference user equipment may be further based on the received configuration information.

The method may further comprise: sending, to the location management function or server user equipment, information indicating the identity of the selected reference user equipment. 10 The one or more conditions may comprise one or more of: tolerable ratio of uninterrupted availability of the reference user equipment over a duration of the sidelink positioning session; acceptable stability of a time reference of the reference user equipment; allowable location uncertainty of the reference user equipment; and allowable mobility status of the reference user equipment.

According to an aspect, there is provided a method comprising: sending, to a first user equipment in a sidelink positioning session with one or more second user equipments, configuration information indicating one or more conditions for reference user equipment selection.

The method may further comprise: receiving, from the first user equipment, information indicating a selected reference user equipment.

The method may be performed by one of: a server user equipment or an apparatus for a location management function.

According to an aspect there is provided a method comprising: sending, to an apparatus, reference user equipment selection assistance information for selecting a reference user equipment in a sidelink positioning session between a first user equipment and at least one second user equipment including the second user equipment.

The method may further comprise: receiving, from the apparatus, a notification that the second user equipment has been selected as the reference user equipment for the sidelink positioning session.

The method may further comprise: receiving, from the apparatus, a request for the reference user equipment selection assistance information, wherein the sending the reference user equipment selection assistance information may be based on receiving the request.

The reference user equipment selection assistance information may comprise one or more of availability information of the second user equipment; synchronization information of the second user equipment; location information of the second user equipment; and mobility information of the second user equipment.

According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, from one or more second user equipments in a sidelink positioning session with a first user equipment, respective reference user equipment selection assistance information; selecting a reference user equipment from among the one of the one or more second user equipments based on the reference user equipment selection assistance information; and sending, to the selected reference user equipment, an indication that it has been selected as the reference user equipment for the sidelink positioning session.

The instructions, when executed by the apparatus, may cause the apparatus to further perform: sending, to the one or more second user equipments, a request for the reference user equipment selection assistance information, wherein the receiving the reference user equipment selection assistance information may be based on sending the request.

The apparatus may be a server user equipment or an apparatus for a location management function, and the instructions, when executed by the apparatus, may cause the apparatus to further perform: sending, to the first user equipment, information indicating the identity of the selected reference user equipment.

The apparatus may be the first user equipment, and the instructions, when executed by the apparatus, may cause the apparatus to further perform: receiving, from a location management function or server user equipment, configuration information indicating one or more conditions for reference user equipment selection, wherein selecting the reference user equipment may be further based on the received configuration information.

The instructions, when executed by the apparatus, may cause the apparatus to further perform: sending, to the location management function or server user equipment, information indicating the identity of the selected reference user equipment.

According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: sending, to a first user equipment in a sidelink positioning session with one or more second user equipments, configuration information indicating one or more conditions for reference user equipment selection.

The instructions, when executed by the apparatus, may cause the apparatus to further perform: receiving, from the first user equipment, information indicating a selected reference user equipment.

According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by a second user equipment, cause the second user equipment to perform at least the following: sending, to an apparatus, reference user equipment selection assistance information for selecting a reference user equipment in a sidelink positioning session between a first user equipment and at least one second user equipment including the second user equipment.

The instructions, when executed by the second user equipment, may cause the second user equipment to further perform: receiving, from the apparatus, a notification that the second user equipment has been selected as the reference user equipment for the sidelink positioning session.

The instructions, when executed by the second user equipment, may cause the second user equipment to further perform: receiving, from the apparatus, a request for the reference user equipment selection assistance information, wherein the sending the reference user equipment selection assistance information may be based on receiving the request.

According to an aspect, there is provided a non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the method according to any of the preceding aspects.

In the above, many different embodiments have been described. It should be appreciated that further embodiments may be provided by the combination of any two or more of the embodiments described above.

DESCRIPTION OF FIGURES

Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which: Figure 1 shows a representation of a network system according to some example 15 embodiments; Figure 2 shows a representation of a control apparatus according to some example embodiments; Figure 3 shows a representation of an apparatus according to some example embodiments; Figure 4 illustrates an example sidelink positioning scenario; Figure 5 shows methods according to some examples; and Figures 6 and 7 show signalling exchanges according to some examples.

DETAILED DESCRIPTION

A non-exhaustive list of some abbreviations used throughout the present disclosure is provided below for reference: 3GPP 3rd Generation Partnership Project DL Downlink ID Identifier lloT Industrial Internet of Things LMF Location Management Function NR New Radio SL Sidelink PRS Positioning Reference Signal RTT Round-Trip Time Rx Receiver / Receive TDOA Time Difference of Arrival (TDOA) TRP Transmit Receive Point Tx Transmitter / Transmit V2X Vehicle-to-anything UE User Equipment UL Uplink In the following certain embodiments are explained with reference to mobile communication devices capable of communication via a wireless cellular system and mobile communication systems serving such mobile communication devices. Before explaining in detail the exemplifying embodiments, certain general principles of a wireless communication system, access systems thereof, and mobile communication devices are briefly explained with reference to Figures 1, 2 and 3 to assist in understanding the technology underlying the described examples.

Figure 1 shows a schematic representation of a 5G system (5GS). The 5GS may be comprised by a terminal or user equipment (UE), a 5G radio access network (5GRAN) or next generation radio access network (NG-RAN), a 5G core network (5GC), one or more application function (AF) and one or more data networks (DN).

The 5G-RAN may comprise one or more gNodeB (GNB) or one or more gNodeB (GNB) distributed unit functions connected to one or more gNodeB (GNB) centralized unit functions. The 5GC may comprise the following entities: Network Slice Selection Function (NSSF); Network Exposure Function; Network Repository Function (NRF); Policy Control Function (PCF); Unified Data Management (UDM); Application Function (AF); Authentication Server Function (AUSF); an Access and Mobility Management Function (AMF); and Session Management Function (SMF). Figure 1 also shows the various interfaces (N1, N2 etc.) that may be implemented between the various elements of the system.

Figure 2 illustrates an example of a control apparatus 200 for controlling a function of the 5GRAN or the 5GC as illustrated on Figure 1. The control apparatus may comprise at least one random access memory (RAM) 211a, at least on read only memory (ROM) 211b, at least one processor 212, 213 and an input/output interface 214. The at least one processor 212, 213 may be coupled to the RAM 211a and the ROM 211b. The at least one processor 212, 213 may be configured to execute an appropriate software code 215. The software code 215 may for example allow to perform one or more steps to perform one or more of the present aspects. The software code 215 may be stored in the ROM 211b. The control apparatus 200 may be interconnected with another control apparatus 200 controlling another function of the 5GRAN or the 5GC. In some embodiments, each function of the 5GRAN or the 5GC comprises a control apparatus 200. In alternative embodiments, two or more functions of the 5GRAN or the 5GC may share a control apparatus.

Figure 3 illustrates an example of a terminal 300, such as the terminal illustrated on Figure 1. The terminal 300 may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a user equipment, a mobile station (MS) or mobile device such as a mobile phone or what is known as a 'smart phone', a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, an Internet of things (loT) type communication device or any combinations of these or the like. The terminal 300 may provide, for example, communication of data for carrying communications. The communications may be one or more of voice, electronic mail (email), text message, multimedia, data, machine data and so on.

The terminal 300 may receive signals over an air or radio interface 307 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 3 transceiver apparatus is designated schematically by block 306. The transceiver apparatus 306 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

The terminal 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The at least one processor 301 is coupled to the RAM 302b and the ROM 302a. The at least one processor 301 may be configured to execute an appropriate software code 308. The software code 308 may for example allow to perform one or more of the present aspects. The software code 308 may be stored in the ROM 302a.

The processor, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 304. The device may optionally have a user interface such as key pad 305, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided depending on the type of the device.

In some situations it may be necessary or beneficial to determine the position/location of a UE (which may be referred to herein as "UE positioning"), for example in Vehicle-to-anything (V2X) applications.

In some examples, UE positioning may be implemented using sidelink (SL) communication. UE positioning using SL communication may be referred to herein as "SL positioning".

In some examples, SL positioning may be based on transmissions of SL positioning reference signals (PRS) by one or more anchor UEs to be received by a target UE. Here, the target UE is the UE to be positioned and the one or more anchor UEs are one or more UEs supporting the positioning of the target UE. The target UE may be positioned using, for example, SL time difference on arrival (TDOA) methods, or SL PRS exchange between the anchor UE(s) and target UE in SL (multi-)round trip time (RTT) methods. Some methods may enable localization of the target UE and/or ranging of target UE with respect to a reference UE (e.g. anchor UE) within latency and accuracy requirements of the corresponding SL positioning mechanism.

Reference is made to Figure 4, which illustrates an example SL positioning scenario where a target UE (UE-T) is performing SL positioning by receiving SL PRS from three anchor UEs (UE-A1, UE-A2 and UE-A3) and determining its location using SL TDOA method. Here, the anchor UEs provide SL PRS assistance information (including SL PRS) to the target UE. While not shown in Figure 4, in some scenarios (e.g., when within the coverage area of a base station), a location management function (LMF) may coordinate the SL positioning where the SL PRS transmissions from anchor UEs, the reference UE for SL positioning, etc. may be configured by the LMF.

In general, for TDOA methods the time difference of arrival of PRS with respect to a reference time may be used for position estimation. In some examples, such as Uu-based NR positioning, the reference time can be based on a transmit-receive point (TRP). For example, in DL positioning, a UE may measure a reference signal time difference (RSTD) for different PRS with respect to a received time of a PRS from the reference TRP. The LMF may configure the UE with the reference TRP. Alternatively, the UE may itself select reference TRP and report the selected TRP to the LMF.

In SL TDOA there may also be a need for a reference time. Accordingly, a reference UE may be introduced. In some examples, a SL reference signal time difference (SL RSTD) may be defined as the SL relative timing difference between the UE j and the reference UE i, defined as TSubframe_SL-Rxj TSubframe_SL-Rxi, where: * TSubframe_SL-Rxj is the time when the UE receives the start of one subframe from UE j. ;* TSubframeSL-Rxi is the time when the UE receives the corresponding start of one subframe from UE i that is closest in time to the subframe received from UE j.

As used herein, 'reference UE' refers to the UE which is used for reference timing in SL positioning (e.g., RSTD measurement and report). In some examples, a reference UE for SL positioning at a target UE may be one of the anchor UEs that are supporting the target UE.

Therefore there is a need to select the reference UE to enable SL TDOA methods of UE positioning. A random or suboptimal selection of the reference UE may impact the SL positioning accuracy, since that positioning accuracy may depend on the accuracy of the RSTD reports, which may lead to suboptimal performance.

For example, since measurements performed for all anchor UEs may be with respect to the reference UE, in case of any reference timing issue (e.g. instability of time-reference of the reference UE), the SL RSTD measured may not be accurate and hence may lead to poor SL positioning accuracy performance. Furthermore, location uncertainty of the reference UE may also impact the accuracy performance.

Furthermore, the reference UE selection may involve information exchange / signalling between a set of UEs (e.g. target UEs, candidate anchor/reference UEs) and network entities (e.g. LMF). Hence, frequent change of reference UE may lead to a large signalling overhead and latency.

Some examples may provide mechanisms for reference UE selection to address one or more of these problems.

Reference is made to Figure 5, which shows methods according to some examples.

At 500, a method comprises receiving, from one or more second user equipments in a sidelink positioning session with a first user equipment, respective reference user equipment selection assistance information.

At 502, the method comprises selecting a reference user equipment from among the one of the one or more second user equipments based on the reference user equipment selection assistance information.

At 504, the method comprises sending, to the selected reference user equipment, an indication that it has been selected as the reference user equipment for the sidelink positioning session.

The method of steps 500-504 may be performed by one of: the first user equipment, a server user equipment, or a location management function.

At 506, a method comprises sending, to a first user equipment in a sidelink positioning session with one or more second user equipments, configuration information indicating one or more conditions for reference user equipment selection.

The method of step 506 may be performed by a server user equipment or a location management function.

At 508, a method comprises sending, to an apparatus, reference user equipment selection assistance information for selecting a reference user equipment in a sidelink positioning session between a first user equipment and at least one second user equipment including the second user equipment.

The method of step 508 may be performed by a second user equipment. The apparatus may comprise one of: the first user equipment, a server user equipment, or a location management function.

In some examples, the first UE may be a target UE, e.g. the UE that is being positioned. In some examples the second UE may be an anchor UE, e.g. a UE that assists or supports a positioning session (e.g. a sidelink positioning session) of the first UE.

In some examples a node (e.g. target UE) may be configured to perform reference UE selection. The selection may be based on reference UE selection assistance information. The reference UE selection assistance information may comprise one or more of: availability information of candidate refence UEs; synchronization information of the candidate refence UEs; location information of the candidate reference UEs; and mobility information of the candidate refence UEs.

In some examples the availability information of a candidate reference UE may comprise information indicating an expected availability of the candidate reference UE. In some examples the availability information may comprise information indicating that a candidate reference UE intends to become unavailable. For example, the candidate reference UE may intend to become unavailable after a certain amount of time and drop out of the positioning session. Such UEs may be deprioritized as reference UEs to avoid additional overhead for "resetting" the positioning session (and set a new reference UE) once the reference UE is lost.

In some examples the target UE may determine, based on the availability information of a candidate reference UE, a ratio of the candidate reference UE's expected uninterrupted availability (in time duration) for the positioning session and the intended duration of the positioning session.

For example, for a SL positioning session intended to last 10 minutes, the target UE may determine a ratio of 0.8 for a first candidate UE that indicates an expected availability of 8 minutes availability during the intended SL positioning session duration, and a ratio of 0.5 for a second candidate UE that indicates an expected availability of 5 minutes availability during the intended SL positioning session duration. The target UE may in some examples prioritize the first candidate reference UE over the second candidate reference UE to maximize the amount of time of the intended SL positioning session before having to reselect the reference U E. In some examples, the synchronization information of a candidate reference UE may indicate a synchronization level of the candidate reference UE. The synchronization information may comprise at least a stability of the time reference of the candidate reference UE. The synchronization information may indicate a time reference (e.g. gNB) of the candidate reference UE.

In some examples, the location information of a candidate refence UE may comprise an indication of the location of the candidate reference U E and may further comprise an indication of the uncertainty of the location of the candidate reference UE. The location of the reference UE may impact the positioning performance (e.g., in terms of positioning accuracy) with respect to the target UE location.

In some examples, the mobility information of a candidate reference UE may comprise information indicating the mobility of the candidate reference UE -for example one or more of relative velocity, relative trajectory, proximity. In some examples, candidate reference UEs with high mobility may be deprioritized due to the relatively high uncertainty of their absolute location.

In some examples, a node (e.g. UE) may receive a reference UE selection configuration from another node, such as an LMF or server UE. A server UE may be understood as being a UE that performs configuring of SL PRS for SL positioning -for example configuring anchor UEs transmitting a SL PRS (which may also be referred to as "DL-like SL positioning") or configuring target UE(s) transmitting SL PRS (which may also be referred to as "UL-like SL positioning"). The UE selection configuration may comprise reference UE selection conditions based on the aforementioned information. That is to say, in some examples the other node (e.g. LMF, server UE) may obtain the UE assistance information from the candidate reference UEs and select the reference UE based on the reference UE selection assistance information. In other examples, the node (e.g. UE) may autonomously perform reference UE selection based on the aforementioned information.

Reference is made to Figure 6, which shows a signalling exchange according to some examples. In the example of Figure 6, the target UE obtains the reference UE selection assistance information and performs the selection of the reference UE.

At 600, the target UE (UE-T) may establish a SL positioning session with a first anchor UE (UE-A1) and second anchor UE (UE-A2).

Establishing a SL positioning session may involve a signalling exchange between UE-T and UE-A1 and UE-A2, which may include at least anchor discovery procedure, capability information, as well as SL PRS configuration information pertaining to the SL PRS transmitted by the anchor UEs UE-A1 and UE-A2. The SL positioning session may be considered a DL-like SL TDOA SL positioning session.

The UE-T may need to select a reference UE among anchor UEs, for example for performing SL RSTD measurement.

At 602, the LMF or server UE may send configuration information to the target UE. The configuration information may comprise information indicating one or more conditions for the reference UE selection. The conditions may include one or more of: a) Tolerable ratio of uninterrupted availability of the reference UE over positioninci session duration.

The tolerable ratio of uninterrupted availability over positioning session duration may indicate the overhead the network can tolerate.

The ratio may depend on a signalling overhead level that the network (or server UE) can tolerate. For example, if a high overhead can be tolerated the network may allow for multiple changes of the reference UE; whereas if low or zero additional overhead can be tolerated the network may configure the target UE to force only few (or zero) changes of the reference UE.

b) Acceptable stability of time reference of the reference UE.

The network or server UE may configure the target UE with a level of acceptable stability of time reference of the reference UE.

In some examples a UE may be considered to have a stable time reference if the synchronization reference (SyncRef) source of the UE is gNB; or if a percentage of anchor UEs sharing the same SyncRef source as the candidate reference is above a certain threshold.

The configuration of the time reference stability thresholds may follow the QoS of the positioning session, which may be available at LMF and/or server UE.

c) Allowable location uncertainty of reference UE. The LMF or server UE may configure the target UE with an allowable location uncertainty to select the reference UE accordingly. 25 d) Allowable mobility status of reference UE.

o Similar to location uncertainty, the LMF or server UE may configure the target UE with an allowable mobility status to select the reference UE accordingly. This may include, e.g. whether the anchor UE is mobile or static and if mobile, information on its velocity etc. At 604, the target UE may send a request for reference UE selection assistance information to the anchor UEs, and at 606 the target UE may receive the requested reference UE selection assistance information from the anchor UEs. The reference UE selection assistance information may be as described previously.

In some examples the request message sent at 604 may comprise an additional Information Element (1E) to an anchor discovery message. The anchor discovery message may be sent as part of establishing the SL positioning session at 600, or prior to establishing the SL positioning session. The request message for the reference UE selection assistance information may include a request for at least one of: o Prospective (estimated) uninterrupted availability in units of time for the anchor UE, where the availability refers to the availability of anchor UE supporting the positioning session of the target UE; o A synchronization reference source of anchor UE; o Location certainty or uncertainty of anchor UE, e.g. the level of confidence on the anchor UE's information on its own location; and o Mobility information of anchor UE, e.g. whether the anchor UE is mobile or static and if mobile, information on its velocity vector (that is speed and direction of movement), etc. In some examples steps 604 and 606 may be omitted, for example if the target UE already has the UE selection assistance information about the anchor UEs (e.g., from previous SL positioning session, or from information exchanged during SL positioning establishment).

At 608, the target UE selects a reference UE based on the configuration information (received from the network or server UE at 602) and the UE selection assistance information (received from the anchor UEs at 606 or previously).

In some examples the target UE may determine the ratio of (candidate reference UE availability) over (positioning session duration).

In some examples the target UE may determine the stability of the candidate reference UE with respect to their synchronization source (e.g., whether it is gNB) and with respect to the percentage of anchor UEs which share the same synchronization reference source as the candidate reference.

In some examples the target UE may determine the impact on the positioning accuracy for a candidate reference UE based on the location uncertainty and mobility information of the candidate reference UE.

In some examples, the target UE may determine a mobility status of the candidate reference UE based on the mobility information. For example, if the mobility information indicates that the UE is mobile and moving with a certain velocity vector (that is speed and direction of movement), the target UE may determine that the mobility status of the candidate reference UE is allowable or unallowable.

The target UE may then select the reference UE from among the candidate reference UEs based on the determined information.

At 610, the target UE may send information indicating the identity of the selected reference UE to the LMF or server UE.

At 612, the target UE may notify the selected candidate reference UE that it has been selected as a reference UE for the positioning session. In the example shown in Figure 6, this is the first anchor UE (UE-A1). In some examples, the target UE may send, to the other anchor UEs, a notification of the selected reference UE.

Reference is made to Figure 7, which shows a signalling exchange according to some examples. In the example of Figure 7, the LMF (or server UE) obtains the reference UE selection assistance information and performs the selection of the reference UE, and then indicates the selection to the UE.

At 700, as described previously in relation to Figure 6, the target UE (UE-T) may establish a SL positioning session with a first anchor UE (UE-A1) and second anchor UE (UE-A2).

At 702, the LMF (or server UE) may send a request for reference UE selection assistance information to the anchor UEs, and at 704 the target UE may receive the requested reference UE selection assistance information from the anchor UEs. The reference UE selection assistance information may be as described previously.

In some examples the request message sent at 702 may comprise a request for at least one of: o Prospective (estimated) uninterrupted availability in units of time for the anchor UE, where the availability refers to the availability of anchor UE supporting the positioning session of the target UE; o A synchronization reference source of anchor UE; o Location certainty or uncertainty of anchor UE, e.g. the level of confidence on the anchor UE's information on its own location; and o Mobility information of anchor UE, e.g. whether the anchor UE is mobile or static and if mobile, information on its velocity vector (that is speed and direction of movement), etc. At 706, the LMF (or server UE) may select a reference UE based on the UE selection assistance information (received from the anchor UEs at 702). The LMF (or server UE) may employ a similar selection mechanism to the described above in relation to Figure 6.

For example, the selection of the reference UE may be further based on configuration information. The configuration information may comprise information indicating one or more conditions for the reference UE selection. The conditions may include one or more of: a) Tolerable ratio of uninterrupted availability of the reference UE over positioning session duration. The tolerable ratio of uninterrupted availability over positioning session duration may indicate the overhead the network can tolerate.

The ratio may depend on a signalling overhead level that the network (or server UE) can tolerate. For example if a high overhead can be tolerated the network may allow for multiple changes of the reference UE; whereas if low or zero additional overhead can be tolerated the network may select a reference UE with the intention of there being only few (or zero) changes of the reference U E. b) Acceptable stability of time reference of the reference UE.

The selection may be based on a level of acceptable stability of time reference of the reference UE.

c) Allowable location uncertainty of reference UE.

The LMF or server UE may select the reference UE based on an allowable location uncertainty.

d) Allowable mobility status of reference UE.

Similar to location uncertainty, the LMF or server UE may select the reference UE based on an allowable mobility status. This may include, e.g. whether the anchor UE is mobile or static and if mobile, information on its velocity vector (that is speed and direction of movement), etc. At 708, the LMF (or server UE) may send information indicating the identity of the selected reference UE to the target UE.

At 710, the LMF (or server UE) may notify the selected reference UE, that it has been selected as a reference UE for the SL positioning session.

Some examples have therefore been provided whereby the selection of the reference UE is based on UE selection assistance information and configuration information. Some examples may thus select a reference UE for a SL positioning session that best suits the network requirements. For example, when the network determines that little or no additional signalling overhead can be tolerated, the network may configure the target UE to select (or the network itself may select) a reference UE that is most stable and most likely to be available for the entire duration of the SL positioning session, even if this comes at a cost of lower positioning accuracy. Likewise, if additional overhead can be tolerated, the network may configure the target UE to select (or the network itself may select) a reference UE that is less stable or likely to become unavailable during the SL positioning session (thereby being more likely to lead to reference UE reselection), which may allow the selection of a reference UE that provides a higher positioning accuracy. Some examples may therefore enhance SL positioning session procedures.

In some examples, there is provided an apparatus comprising means for: receiving, from one or more second user equipments in a sidelink positioning session with a first user equipment, respective reference user equipment selection assistance information; selecting a reference user equipment from among the one of the one or more second user equipments based on the reference user equipment selection assistance information; and sending, to the selected reference user equipment, an indication that it has been selected as the reference user equipment for the sidelink positioning session.

In some examples there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from one or more second user equipments in a sidelink positioning session with a first user equipment, respective reference user equipment selection assistance information; select a reference user equipment from among the one of the one or more second user equipments based on the reference user equipment selection assistance information; and send, to the selected reference user equipment, an indication that it has been selected as the reference user equipment for the sidelink positioning session.

In some examples, there is provided an apparatus comprising means for: sending, to a first user equipment in a sidelink positioning session with one or more second user equipments, configuration information indicating one or more conditions for reference user equipment selection.

In some examples there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: send, to a first user equipment in a sidelink positioning session with one or more second user equipments, configuration information indicating one or more conditions for reference user equipment selection.

In some examples there is provided a second user equipment comprising means for: sending, to an apparatus, reference user equipment selection assistance information for selecting a reference user equipment in a sidelink positioning session between a first user equipment and at least one second user equipment including the second user equipment.

there is provided a second user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the second user equipment at least to: send, to an apparatus, reference user equipment selection assistance information for selecting a reference user equipment in a sidelink positioning session between a first user equipment and at least one second user equipment including the second user equipment.

It is understood that references in the above to various network functions (e.g., to an LMF, etc.) may comprise apparatus that perform at least some of the functionality associated with those network functions. Further, an apparatus comprising a network function may comprise a virtual network function instance of that network function.

It should be understood that the apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and/or reception. Although the apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities.

It is noted that whilst some embodiments have been described in relation to 5G networks, similar principles can be applied in relation to other networks and communication systems. Therefore, although certain embodiments were described above by way of example with reference to certain example architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein.

It is also noted herein that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

As used herein, "at least one of the following: <a list of two or more elements>" and "at least one of <a list of two or more elements>" and similar wording, where the list of two or more elements are 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 the elements.

In general, the various embodiments may be implemented in hardware or special purpose circuitry, software, logic or any combination thereof. Some aspects of the disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

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 in only analog and/or digital circuitry) and (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (h) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation." This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

The embodiments of this disclosure may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and/or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computer-executable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it.

Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The physical media is a non-transitory media.

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 on data storage persistency (e.g., RAM vs. ROM).

The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

Embodiments of the disclosure may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process.

Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

The scope of protection sought for various embodiments of the disclosure is set out by the independent claims. The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the disclosure.

The foregoing description has provided by way of non-limiting examples a full and informative description of the exemplary embodiment of this disclosure. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this disclosure will still fall within the scope of this invention as defined in the appended claims. Indeed, there is a further embodiment comprising a combination of one or more embodiments with any of the other embodiments previously discussed.

Claims

CLAIMS1. An apparatus comprising means for: receiving, from one or more second user equipments in a sidelink positioning session with a first user equipment, respective reference user equipment selection assistance information; selecting a reference user equipment from among the one of the one or more second user equipments based on the reference user equipment selection assistance information; and sending, to the selected reference user equipment, an indication that it has been selected as the reference user equipment for the sidelink positioning session.
2. The apparatus of claim 1, further comprising means for: sending, to the one or more second user equipments, a request for the reference user equipment selection assistance information, wherein the receiving the reference user equipment selection assistance information is based on sending the request.
3. The apparatus of claim 1 or 2, wherein the apparatus is a server user equipment or an apparatus for a location management function, and wherein the apparatus further comprises means for: sending, to the first user equipment, information indicating the identity of the selected reference user equipment.
4. The apparatus of claim 1 or 2, wherein the apparatus is the first user equipment, and wherein the apparatus further comprises means for: receiving, from a location management function or server user equipment, configuration information indicating one or more conditions for reference user equipment selection, wherein selecting the reference user equipment is further based on the received configuration information.
5. The apparatus of claim 4, further comprising means for: sending, to the location management function or server user equipment, information indicating the identity of the selected reference user equipment.
6. The apparatus of claim 4 or 5, wherein the one or more conditions comprise one or more of: tolerable ratio of uninterrupted availability of the reference user equipment over a duration of the sidelink positioning session; acceptable stability of a time reference of the reference user equipment; allowable location uncertainty of the reference user equipment; and allowable mobility status of the reference user equipment.
7. The apparatus of any preceding claim, wherein the reference user equipment selection assistance information comprises one or more of availability information of the second user equipment; synchronization information of the second user equipment; location information of the second user equipment; and mobility information of the second user equipment.
8. The apparatus of claim 7, wherein: the availability information comprises information indicating an expected availability and/or unavailability of the second user equipment to support the sidelink positioning session of the first user equipment; the synchronization information comprises information indicating a time reference of the second user equipment; the location information comprises information indicating a location of the second user equipment and information indicating an uncertainty of the location of the second user equipment; and the mobility information comprises information indicating one or more of: a relative velocity of the second user equipment, a relative trajectory of the second user equipment, and a proximity of the second user equipment.
9. An apparatus comprising means for: sending, to a first user equipment in a sidelink positioning session with one or more second user equipments, configuration information indicating one or more conditions for reference user equipment selection.
10. The apparatus of claim 9, wherein the one or more conditions comprise one or more 35 of: tolerable ratio of uninterrupted availability of the reference user equipment over a duration of the sidelink positioning session; acceptable stability of a time reference of the reference user equipment; allowable location uncertainty of the reference user equipment; and allowable mobility status of the reference user equipment.
11. The apparatus of claim 9 or 10, further comprising means for: receiving, from the first user equipment, information indicating a selected reference user equipment.
12. The apparatus of any of claims 9 to 11, wherein the apparatus is one of: a server user equipment or an apparatus for a location management function.
13. A second user equipment comprising means for: sending, to an apparatus, reference user equipment selection assistance information for selecting a reference user equipment in a sidelink positioning session between a first user equipment and at least one second user equipment including the second user equipment.
14. The second user equipment of claim 13, further comprising means for: receiving, from the apparatus, a notification that the second user equipment has been selected as the reference user equipment for the sidelink positioning session. 20
15. The second user equipment of claim 13 or 14, further comprising means for: receiving, from the apparatus, a request for the reference user equipment selection assistance information, wherein the sending the reference user equipment selection assistance information is based on receiving the request.
16. The second user equipment of any of claims 13 to 15, wherein the reference user equipment selection assistance information comprises one or more of: availability information of the second user equipment; synchronization information of the second user equipment; location information of the second user equipment; and mobility information of the second user equipment.
17. The second user equipment of claim 16, wherein: the availability information comprises information indicating an expected availability and/or unavailability of the second user equipment to support the sidelink positioning session of the first user equipment; the synchronization information comprises information indicating a time reference of the second user equipment; the location information comprises information indicating a location of the second user equipment and information indicating an uncertainty of the location of the second user equipment; and the mobility information comprises information indicating one or more of: a relative velocity of the second user equipment, a relative trajectory of the second user equipment, and a proximity of the second user equipment.
18. The second user equipment of any of claims 13 to 17, wherein the apparatus comprises one of: the first user equipment; an apparatus for a location management function; or a server user equipment.
19. An apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from one or more second user equipments in a sidelink positioning session with a first user equipment, respective reference user equipment selection assistance information; select a reference user equipment from among the one of the one or more second user equipments based on the reference user equipment selection assistance information; and send, to the selected reference user equipment, an indication that it has been selected as the reference user equipment for the sidelink positioning session.
20. An apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: send, to a first user equipment in a sidelink positioning session with one or more second user equipments, configuration information indicating one or more conditions for reference user equipment selection.
21. A second user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the second user equipment at least to: send, to an apparatus, reference user equipment selection assistance information for selecting a reference user equipment in a sidelink positioning session between a first user equipment and at least one second user equipment including the second user equipment.
22. A method comprising: receiving, from one or more second user equipments in a sidelink positioning session with a first user equipment, respective reference user equipment selection assistance information; selecting a reference user equipment from among the one of the one or more second user equipments based on the reference user equipment selection assistance information; and sending, to the selected reference user equipment, an indication that it has been selected as the reference user equipment for the sidelink positioning session
23. A method comprising: sending, to a first user equipment in a sidelink positioning session with one or more second user equipments, configuration information indicating one or more conditions for reference user equipment selection.
24. A method comprising: sending, to an apparatus, reference user equipment selection assistance information for selecting a reference user equipment in a sidelink positioning session between a first user equipment and at least one second user equipment including the second user equipment.