WO2025035293A1

WO2025035293A1 - Device discovery for sidelink

Info

Publication number: WO2025035293A1
Application number: PCT/CN2023/112662
Authority: WO
Inventors: Mao Cai; Stepan Kucera
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Priority date: 2023-08-11
Filing date: 2023-08-11
Publication date: 2025-02-20
Anticipated expiration: 2026-02-11

Abstract

Example embodiments of the present disclosure relate to device discovery for sidelink. In an aspect, a first terminal device obtains an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device. The first terminal device transmits, during a discovery procedure for the sidelink positioning procedure, a broadcast message comprising the identifier list. In this way, the efficiency of the discovery process and the signaling overhead may be reduced without extensive one-to-one communications.

Description

DEVICE DISCOVERY FOR SIDELINK

FIELD

Example embodiments of the present disclosure generally relate to the field of communication, and in particular, to terminal devices, network entities, methods apparatuses and a computer readable storage medium for device discovery for sidelink (SL) .

BACKGROUND

In the communication technology, there is a constant evolution ongoing in order to provide efficient and reliable solutions for utilizing wireless communication networks. Each new generation has its own technical challenges for handling different situations and processes that are needed to connect and serve devices connected to wireless networks. To meet the demand for wireless data traffic having increased since deployment of 4th generation (4G) communication systems, efforts have been made to develop an improved 5th generation (5G) , pre-5G, 6G or beyond communication systems.

Currently, different positioning technologies are studied to meet various accuracy requirements and different network coverage use cases. Sidelink positioning/ranging is identified as important to meet high accuracy use cases, especially when global navigation satellite system (GNSS) coverage is unavailable. Recently, standardization of sidelink positioning/ranging is being continuously pushed. However, a solution of device discovery for sidelink is still incomplete and needs further study.

SUMMARY

In general, example embodiments of the present disclosure provide a solution for device discovery for sidelink.

In a first aspect, there is provided a first terminal device. The first terminal device comprises at least one processor and at least one memory storing instructions. When executed by the at least one processor, the instructions cause the first terminal device at least to: obtain an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and transmit, during a discovery procedure for the sidelink positioning procedure, a broadcast message comprising the identifier list.

In a second aspect, there is provided a second terminal device. The second terminal device comprises at least one processor and at least one memory storing instructions. When executed by the at least one processor, the instructions cause the second terminal device at least to: receive, from a first terminal device, a broadcast message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and determine whether the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device.

In a third aspect, there is provided a first network entity. The first network entity comprises at least one processor and at least one memory storing instructions. When executed by the at least one processor, the instructions cause the first network entity at least to:transmit, to a first terminal device, an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and transmit, to a second terminal device, at least one identifier of at least one attribute set satisfied by the second terminal device.

In a fourth aspect, there is provided a second network entity. The second network entity comprises at least one processor and at least one memory storing instructions. When executed by the at least one processor, the instructions cause the second network entity at least to: receive, from a first network entity, a match query message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for a first terminal device and an identifier of the second terminal device; and based on determining that the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device, transmit, to the first network entity, a message indicative of matching between the identifier list and the at least one identifier.

In a fifth aspect, there is provided a method. The method comprises: obtaining, at a first terminal device, an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and transmitting, during a discovery procedure for the sidelink positioning procedure, a broadcast message comprising the identifier list.

In a sixth aspect, there is provided a method. The method comprises: receiving, at a second terminal device from a first terminal device, a broadcast message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and determining whether the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device.

In a seventh aspect, there is provided a method. The method comprises: transmitting, at a first network entity and to a first terminal device, an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and transmitting, to a second terminal device, at least one identifier of at least one attribute set satisfied by the second terminal device.

In an eighth aspect, there is provided a method. The method comprises: receiving, at a second network entity and from a first network entity, a match query message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for a first terminal device and an identifier of the second terminal device; and based on determining that the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device, transmitting, to the first network entity, a message indicative of matching between the identifier list and the at least one identifier.

In a ninth aspect, there is provided an apparatus. The apparatus comprises: means for obtaining an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and means for transmitting, during a discovery procedure for the sidelink positioning procedure, a broadcast message comprising the identifier list.

In a tenth aspect, there is provided an apparatus. The apparatus comprises: means for receiving, from a first terminal device, a broadcast message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and means for determining whether the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device.

In an eleventh aspect, there is provided an apparatus. The apparatus comprises: means for transmitting, to a first terminal device, an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and means for transmitting, to a second terminal device, at least one identifier of at least one attribute set satisfied by the second terminal device.

In a twelfth aspect, there is provided an apparatus. The apparatus comprises: means for receiving, from a first network entity, a match query message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for a first terminal device and an identifier of the second terminal device; and means for based on determining that the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device, transmitting, to the first network entity, a message indicative of matching between the identifier list and the at least one identifier.

In a thirteenth aspect, there is provided a first terminal device . The first terminal device comprises: obtaining circuitry configured to obtain an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and transmitting circuitry configured to transmit, during a discovery procedure for the sidelink positioning procedure, a broadcast message comprising the identifier list.

In a fourteenth aspect, there is provided a second terminal device. The second terminal device comprises: receiving circuitry configured to receive, from a first terminal device, a broadcast message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and determining circuitry configured to determine whether the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device.

In a fifteenth aspect, there is provided a first network entity. The first network entity comprises: transmitting circuitry configured to transmit, to a first terminal device, an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and transmitting circuitry configured to transmit, to a second terminal device, at least one identifier of at least one attribute set satisfied by the second terminal device.

In a sixteenth aspect, there is provided a second network entity. The second network entity comprises: receiving circuitry configured to receive, from a first network entity, a match query message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for a first terminal device and an identifier of the second terminal device; and transmitting circuitry configured to based on determining that the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device, transmit, to the first network entity, a message indicative of matching between the identifier list and the at least one identifier.

In a seventeenth aspect, there is provided a non-transitory computer-readable storage medium comprising program instructions. The program instructions, when executed by an apparatus, cause the apparatus to perform at least the method according to any one of the above fifth to eighth aspect.

In an eighteenth aspect, there is provided a computer program comprising instructions. The instructions, when executed by an apparatus, cause the apparatus to perform at least the method according to any one of the above fifth to eighth aspect.

It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments will now be described with reference to the accompanying drawings, in which:

Fig. 1 illustrates an example of a network environment in which some example embodiments of the present disclosure may be implemented;

Fig. 2A illustrates a flowchart illustrating a communication process in accordance with some example embodiments of the present disclosure;

Fig. 2B illustrates a flowchart illustrating a communication process of obtaining an identifier list for a SL positioning procedure in accordance with some example embodiments of the present disclosure;

Fig. 2C illustrates a flowchart illustrating a communication process in accordance with some example embodiments of the present disclosure;

Fig. 2D illustrates a flowchart illustrating a communication process in accordance with some example embodiments of the present disclosure;

Fig. 3A illustrates a flowchart illustrating a Model A discovery procedure in an out-of-coverage case in accordance with some example embodiment of the present disclosure;

Fig. 3B illustrates a flowchart illustrating a Model B discovery procedure in an out-of-coverage case in accordance with some example embodiment of the present disclosure;

Fig. 4A illustrates a flowchart illustrating a procedure of obtaining DP_IDs in an in-coverage case in accordance with some example embodiment of the present disclosure;

Fig. 4B illustrates a flowchart illustrating a Model A discovery procedure with discovery profiles in an in-coverage case in accordance with some example embodiment of the present disclosure;

Fig. 4C illustrates a flowchart illustrating a Model B discovery procedure with discovery profiles in an in-coverage case in accordance with some example embodiment of the present disclosure;

Fig. 5A illustrates a flowchart illustrating a procedure for SL-MO-LR in accordance with some example embodiment of the present disclosure;

Fig. 5B illustrates a flowchart illustrating a procedure for SL-MT-LR in accordance with some example embodiment of the present disclosure;

Fig. 5C illustrates a flowchart illustrating a procedure for SL-MT-LR for periodic, triggered location events in accordance with some example embodiment of the present disclosure;

Fig. 6 illustrates a flowchart of an example method implemented at a first terminal device in accordance with some example embodiments of the present disclosure;

Fig. 7 illustrates a flowchart of an example method implemented at a second terminal device in accordance with some example embodiments of the present disclosure;

Fig. 8 illustrates a flowchart of an example method implemented at a first network entity in accordance with some example embodiments of the present disclosure;

Fig. 9 illustrates a flowchart of an example method implemented at a second network entity in accordance with some example embodiments of the present disclosure;

Fig. 10 illustrates a simplified block diagram of a device that is suitable for implementing some example embodiments of the present disclosure; and

Fig. 11 illustrates a block diagram of an example of a computer-readable medium in accordance with some example embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar elements.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein may be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

References in the present disclosure to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof. 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.

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

(ii) 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 (for example, 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.

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a NR NB (also referred to as a gNB) , a Remote Radio Unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology. In the following description, the terms “network device” and “network node” may be used interchangeably.

The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE) , a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , or an Access Terminal (AT) . The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) , an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD) , a vehicle, a drone, a medical device and applications (for example, remote surgery) , an industrial device and applications (for example, a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts) , a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. In the following description, the terms “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

As mentioned above, in recent years, 5G NR positioning has attracted much attention in the wireless communication world. Embodiments of this disclosure relates to 5G NR positioning as studied by the third generation partnership project (3GPP) in the enhanced positioning work item (WI) of Release 18. In particular, it concerns reference UE discovery and selection for SL positioning purposes.

The discovery process for ranging &SL in TS 23.586 is same as legacy proximity-based service (ProSe) defined in TS 23.304. As a result, the search for appropriate SL positioning reference UEs is basically blind following a trial-and-error approach. Thus, the discovery process for ranging &SL is complex and lengthy and requires extensive signaling and processing by the UEs /devices. There is a need to enhance the discovery process for sidelink.

Fig. 1 illustrates a schematic diagram of a communication environment 100 in which some embodiments of the present disclosure can be implemented. As shown in Fig. 1, the communication environment 100, which may also be referred to as a communication network 100 or a communication system 100, includes an access network device 110, a core network 140, a terminal device 120-1, a terminal device 120-2, a terminal device 120-3 and a terminal device 120-4 (collectively referred to as terminal devices 120) .

The access network device 110 may support communications with the core network 140, or with another network entity (not shown in Fig. 1) , or both. The core network 140 may comprise multiple network entities, such as at least one access and mobility management function (AMF) , at least one location management function (LMF) , at least one policy control function (PCF) , at least one unified data management function (UDM) and so on.

The access network device 110 manages a cell 112 and serves the terminal device 120-1 and the terminal device 120-2 in the cell 112. To transmit data and/or control information, the terminal device 120-1 and the terminal device 120-2 can perform communications with the access network device 110, respectively. In particular, as illustrated in the exemplary scenario of Fig. 1, the terminal device 120-1 may communicate with the access network device 110 via a communication link 115-1, and the terminal device 120-2 may communicate with the access network device 110 via a communication channel 115-2. For transmissions from the access network device 110 to the terminal device 120-1 or 120-2, the communication link 115-1 or 115-2 may be referred to as a downlink, whereas for transmissions from the terminal device 120-1 or 120-2 to the access network device 110, the communication link 115-1 or 115-2 may alternatively be referred to as an uplink.

In addition to the communication links 115-1 and 115-2, the terminal device 120-1 and the terminal device 120-2 can perform a sidelink transmission, which is also referred to as a device-to-device (D2D) communication, via a sidelink 125-1 between the terminal device 120-1 and the terminal device 120-2. For example, in the exemplary scenario of Fig. 1, the terminal device 120-1 is to perform a sidelink transmission 130-1 to the terminal device 120-2 via the sidelink 125-1. In some embodiments, the sidelink transmission 130-1 may be performed on unlicensed band in which various wireless devices based on different wireless technologies share the same wireless spectrum.

As shown in Fig. 1, the terminal devices 120-3 and 120-4 may be outside of the coverage range (namely, outside of the cell 112) of the access network device 110. For the terminal devices 120-3 and 120-4, only sidelink resource selections may exist. For example, the terminal device 120-1 and the terminal device 120-3 can perform a sidelink transmission via a sidelink 125-2 between the terminal device 120-1 and the terminal device 120-3. The terminal device 120-2 and the terminal device 120-4 can perform a sidelink transmission via a sidelink 125-3 between the terminal device 120-2 and the terminal device 120-4. The terminal device 120-3 and the terminal device 120-4 can perform a sidelink transmission via a sidelink 125-4 between the terminal device 120-3 and the terminal device 120-4. Although not shown in Fig. 1, sidelink transmissions may be performed between the terminal device 120-1 and the terminal device 120-4 and between the terminal device 120-2 and the terminal device 120-3 via respective sidelinks.

In some embodiments, the access network device 110 may be absent in the communication environment 100. In other words, the terminal devices 120-1, 120-2, 120-3 and 120-4 as well as possibly other terminal devices (not shown) may be outside of the coverage range (namely, outside of the cell 112) of the access network device 110. In such cases, only sidelink resource selections may exist between the terminal devices 120-1, 120-2, 120-3, 120-4 and possibly other terminal devices not shown in Fig. 1.

As used herein, the term “sidelink transmission” generally refers to any transmission performed from one terminal device to another terminal device. The sidelink transmission may be used for transmitting any data or control information associated with sidelink communications, for example, sidelink data, sidelink control information, sidelink feedback information, or the like. As used herein, the term “sidelink channel” may generally refer to any channel used for sidelink communications, for example, Physical Sidelink Shared Channel (PSSCH) , Physical Sidelink Control Channel (PSCCH) , Physical Sidelink Discovery Channel (PSDCH) , Physical Sidelink Broadcast Channel (PSBCH) , Physical Sidelink Feedback Channel (PSFCH) , and other existing or future sidelink channels.

Although the core network device 140, the access network device 110 and the terminal devices 120-1, 120-2, 120-3 and 120-4 are described in the communication environment 100 of Fig. 1, embodiments of the present disclosure may equally apply to any other suitable communication devices in communication with one another. That is, embodiments of the present disclosure are not limited to the exemplary scenarios of Fig. 1. In this regard, it is noted that although the access network device 110 is schematically depicted as a base station and the terminal devices 120 are schematically depicted as mobile phones in Fig. 1, it is understood that these depictions are exemplary in nature without suggesting any limitation. In other embodiments, the access network device 110 and the terminal devices 120 may be any other communication devices, for example, any other wireless communication devices.

In case the terminal devices 120-1, 120-2, 120-3 and 120-4 are vehicle-mounted terminal devices, communication relate to them may be referred to as a V2X communication. More generally, although not shown in Fig. 1, the V2X communication related to the terminal devices 120 may comprise a communication channel between the terminal devices 120 and any other communication device, including but not limited to, an infrastructure device, another vehicle-mounted terminal device, a device of a pedestrian, a roadside unit, or the like. Furthermore, although not shown, all the communication links as shown in Fig. 1 may be via one or more relays.

It is to be understood that the particular number of various communication devices, the particular number of various communication links, the particular number of other elements, and the particular shape of the cell 112 as shown in Fig. 1 is for illustration purpose only without suggesting any limitations. The communication environment 100 may include any suitable number of communication devices, any suitable number of communication links, any suitable number of other elements and any suitable shape of the cell 112 adapted for implementing embodiments of the present disclosure. In addition, it should be appreciated that there may be various wireless as well as wireline communications (if needed) among all of the communication devices.

Communication in the communication environment 100 may be implemented according to any proper communication protocol (s) , comprising but not limited to, cellular communication protocols of the first generation (1G) , the second generation (2G) , the third generation (3G) , the fourth generation (4G) and the fifth generation (5G) , NR-U and the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and/or any other protocols currently known or to be developed in the future. Moreover, such communication may utilize any appropriate wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA) , Frequency Division Multiple Access (FDMA) , Time Division Multiple Access (TDMA) , Frequency Division Duplex (FDD) , Time Division Duplex (TDD) , Multiple-Input Multiple-Output (MIMO) , Orthogonal Frequency Division Multiple (OFDM) , Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and/or any other technologies currently known or to be developed in the future.

In 3GPP SA2#157, ranging &SL stage 2 has defined the Release 18 architecture for ranging &SL in TS 23.586. The discovery process defined for ranging &SL reuses the legacy procedure as defined in ProSe TS 23.304. For instance, Model A discovery for latest Release 18 ranging is defined in clause 6.4.2.1 in TS 23.586, which is the same as legacy Model A discovery defined in clause 6.3.2 in TS 23.304. For Model B discovery, ranging &SL location service (LCS) is also the same as ProSe as per clause 6.4.2 of TS 23.586.

However, the ProSe procedure and the ranging &SL procedure have different use cases. In ProSe, as per TS 23.304, “5G ProSe Direct Discovery is defined as the process that detects and identifies another UE in proximity via NR PC5 reference point. ” ProSe has the purpose of discovering relay UEs for a remote UE. In ranging &SL, as per TS 23.586, the discovery process is meant to serve multi-lateration purposes of “the determination of the distance between two UEs or more UEs and/or the direction of one UE (i.e. target UE) from another UE (i.e. reference UE) via PC5 interface” .

The actual geometrical distribution of the reference UEs with respect to the target UE and each other is critical in ranging &SL, not just the sheer proximity of the reference UEs to the target UE as in ProSe. Furthermore, SL positioning is fundamentally based on multi-lateration. Thus, multiple reference UEs must be discovered. Moreover, these UEs must satisfy minimum capability requirements defined in clause 6 in TS 23.586 and clause 6.20 in TS 23.273 that are unknown to the UEs during the initial discovery phase.

As the ranging &SL discovery mechanisms copy the basic functionality of ProSe, the search for appropriate SL positioning reference UEs is basically blind following a trial-and-error approach. Such discovery process is complex and lengthy and requires extensive signaling and processing by the UEs/devices. Obviously, such discovery process is an impractical design. In particular, if a unicast is used for discovery and capability exchange (e.g., when 1-to-1 communications based on unicast is proposed to be used as a default mode of communication even in dense multi-UE topologies) , the process would be lengthy and extremely inefficient when all UEs with overlapping capabilities are involved in the discovery process.

Various UE roles are needed based on the procedures in SL LCS. These UE roles are decided during the discovery process based on the capabilities (and runtime parameters/environments) of these UEs. There are multiple logical and conceptual UE roles. Meanwhile, UE platforms are mainly android and IOS, thus, related devices are highly homogenized. In this case, if there are hundreds of UE nearby to be discovered, it is likely that most of those UEs could express the same roles including all the options of located UE /reference UE/positioning server UE. This means that there could be many UEs being discovered and their roles can be identical or inter-changeable. There is no intelligence that discoverer UE could assign a correct role to each UE.

Another issue is that as per TS 23.586, there might be a ripple effect of unlimited spreading of discovery process. In particular, a target UE may trigger or perform a discovery process and a list of nearby located UE (s) can be discovered and selected. Then, the discovered nearby located UE could also be re-located in a new session in which the discovered nearby located UE will take the role of ‘a target UE’ as defined in clause 6.20.1, “Target UE sends a request to the located UE (s) to trigger 5GC-MO-LR procedure to let the located UE (s) acquire their own absolute location. ” When more nearby located UEs become target UE (s) and more new LCS sessions are established, the affected area could expand endlessly. Since the ranging &SL LCS is a service with multiple UEs/devices involved, there is a need to filter out unnecessary UEs and avoid potential massive signaling.

Only the core network (LMF/AMF) with a complete view may have sufficient information to filter out unnecessary UEs to be discovered and leave the effective roles for the procedures to achieve the target QoS. For example, as defined in TS 23.586, LMF performs a UE filtering after the discovery process: “Target UE sends the multiple discovered candidate Located UEs to the LMF for the selection. ” However, it still takes a lengthy and confusing discovery process, and cannot solve the issue of the ripple effect of unlimited spreading of discovery process. For instance, a SL-MO-LR procedure is defined in TS 23.273, clause 6.20. In this procedure, step 2 “UE discovery” and step 3 “Establish secure links” could be lengthy and confusing in a high density area. LMF selection after step 9 “Nlmf_Location_Determine Location Request” is also not useful in solving the issue.

In view of the above discussions and analysis, some embodiments of the present disclosure provide a solution for device discovery. This will be described in connection with Figs. 2A-11.

Fig. 2A illustrates a flowchart illustrating a communication process 200A in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the communication process 200A will be described with reference to Fig. 1. It would be appreciated that although the communication process 200A has been described referring to the network environment 100 of Fig. 1, this communication process 200A may be likewise applied to other similar communication scenarios.

The process 200A may involve a first terminal device 220-1 and a second terminal device 220-2. The first terminal device 220-1 and the second terminal device 220-2 may be implemented as any of the terminal devices 120 as illustrated in Fig. 1. For example, the first terminal device 220-1 may be the terminal device 120-1 or 120-2 in coverage range, or the terminal device 120-3 or 120-4 out of coverage range, or possibly another terminal device not shown in Fig. 1. Similarly, the second terminal device 220-2 may be the terminal device 120-1 or 120-2 in coverage range, or the terminal device 120-3 or 120-4 out of coverage range, or possibly another terminal device not shown in Fig. 1.

In the communication process 200A, the first terminal device 220-1 obtains 201 an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device. The first terminal device 220-1 transmits 202, during a discovery procedure for the sidelink positioning procedure, a broadcast message 203 comprising the identifier list. The second terminal device 220-2 receives 204 the broadcast message 203 from the first terminal device 220-1 and determine 205 whether the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device 220-2.

The attribute set may be defined to represent a UE general capability class. By transmitting an identifier of an attribute set, the UE general capability class may be indicated without the need for a transfer of full and detailed UE capability information. In some embodiments, the attribute set may be extended to be related to dynamically generated information not necessarily directly related to UE capability, such as UE status information and environment information. In this way, the efficiency and accuracy of UE filtering and selection may be improved and the signaling overhead in the discovery process may be reduced without extensive one-to-one communications.

In some embodiments, an attribute set may comprise a type of a location request. For example, the location request may be a mobile-terminated location request (MT-LR) , a mobile-originated location request (MO-LR) , network-induced location request (NI-LR) or other possible types of location request.

Alternatively or additionally, the attribute set may comprise at least one role of a terminal device during the discovery procedure. For example, the attribute set may comprise role information of a terminal device during a discovery process. The role information may comprise allowed roles such as located UE, LCS client UE, SL reference UE, positioning server UE, etc. defined in 3GPP TS 23.586 (clause 3.1) . A terminal device may take different UE roles in different areas. The Application Layer ID of a terminal device may assign or may be assigned with different UE roles. For example, in the case of a MT-LR, location requests from different application functions (AFs) may utilize different UE roles for a single terminal device.

Alternatively or additionally, the attribute set may comprise capability information of the terminal device. In one example, the capability information may comprise at least one location services (LCS) and ranging capability. Alternatively or additionally, the capability information may comprise at least one capability defined in at least one of a long term evolution (LTE) positioning protocol (LPP) or a ranging/sidelink positioning protocol (RSPP/SLPP) . For example, the capability information may comprise at least one of LCS and ranging capabilities contained in 5G mobility management (5GMM) capabilities, UE capabilities defined in LPP as per 3GPP TS 37.355, or UE capabilities defined in RSPP/SLPP as per 3GPP TS 33.355.

Alternatively or additionally, the attribute set may comprise status information of the terminal device. The status information may comprise related UE status information defined in 3GPP TS 38.523, such as a last-known location and related positioning data (including positioning methods) , etc.

Alternatively or additionally, the attribute set may comprise environment information of the terminal device. In one example, the environment information may comprise at least one enhanced cell identified (ECID) measurement. Alternatively or additionally, the environment information may comprise at least one runtime QoS context for the sidelink positioning procedure. For example, the environment information may comprise NR ECID measurements defined as measurement control system in the RRC protocol in clause 4.3.10 of TS 38.305 and/or QoS parameters for the ranging &SL after the discovery (e.g. as defined by PCF) .

In some embodiments, the first terminal device 220-1 may obtain the identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device based on pre-configuration, e.g., from an operator policy. Such implementations especially apply for the case where the first terminal device 220-1 is out of coverage.

Alternatively, in order to obtain the identifier list, the first terminal device 220-1 may receive the identifier list from a first network entity (e.g., an AMF) during a registration procedure of the first terminal device 220-1. In other words, the identifier list corresponding to the attribute set list for the sidelink positioning procedure for the first terminal device may be previously received and locally stored in the first terminal device 220-1. Such implementations especially apply for the case where the first terminal device 220-1 was initially in coverage but is currently out of coverage.

In an example embodiment, during an initial registration procedure or a periodic registration procedure, the terminal device may be configured with an identifier list corresponding to an attribute set list for the sidelink positioning procedure for the terminal device when the terminal device has a ranging &SL positioning capability. For example, the core network (e.g., the AMF) may combine the registration information of the terminal device with subscription data of the terminal device (e.g., obtained by querying the UDM) and reply the allowed identifier list corresponding to the allowed attribute set list for the sidelink positioning procedure in a registration accept reply.

In some embodiments, in order to obtain the identifier list, the first terminal device 220-1 may receive a request message for the sidelink positioning procedure. The request message may comprise the identifier list. If the request message is received, the discovery procedure may be initiated and the first terminal device 220-1 may transmit the broadcast message 203. For example, the first terminal device 220-1 may receive the identifier list corresponding to the attribute set list for the sidelink positioning procedure for the first terminal device when a positioning procedure for NI-LR or MT-LR of the first terminal device 220-1 is initiated. In an example, when a LMF triggers the positioning request, the core network may define the positioning QoS and identify the minimum required capability for reference UEs to be discovered by the first terminal device 220-1. An identifier list corresponding to the attribute set list satisfying the positioning QoS and minimum required capability is provided to the first terminal device 220-1 to discover terminal devices in the same or similar class. Such implementations especially apply for the case where the first terminal device 220-1 is in coverage.

In some implementations, the request message may further comprise a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device. The broadcast message 203 may also comprise the routing identifier. With the indicated routing identifier, the second terminal device 220-2 receiving the broadcast message 203 may be able to query the same second network entity for the identifier matching.

In some examples, if the first terminal device 220-1 is in coverage, the first terminal device 220-1 may query the core network for the identifier list when the first terminal device 220-1 triggers the positioning process. Reference is now made to Fig. 2B, which illustrates a flowchart illustrating a communication process 200B of obtaining an identifier list for a SL positioning procedure in accordance with some example embodiments of the present disclosure. The communication process 200B may be regarded as a specific example implementation of the step 201 in the process 200A.

For the purpose of discussion, the communication process 200B will be described with reference to Fig. 1. It would be appreciated that although the communication process 200B has been described referring to the network environment 100 of Fig. 1, this communication process 200B may be likewise applied to other similar communication scenarios. The process 200B may involve a first terminal device 220-1, a first network entity 240-1 and a second network entity 240-2. The first terminal device 220-1 may be implemented as any of the terminal devices 120 as illustrated in Fig. 1. The first network entity 240-1 and the second network entity 240-2 may be network elements of the core network 140 as illustrated in Fig. 1. For example, the first network entity 240-1 may be implemented as a control plane entity that manages access and mobility (e.g., a mobility management entity (MME) or an AMF) . The second network entity 240-2 may be implemented as a location server, such as a LMF.

As shown in Fig. 2B, in order to obtain the identifier list, the first terminal device 220-1 may transmit 211 a query message 212 comprising an identifier of the first terminal device to a first network entity. The first network entity 240-1 may then transmit 213 a query message 214 to the second network entity 240-2. The query message 214 may comprise the information in the query message 212. The second network entity 240-2 may determine the identifier list based on the query message. In some embodiments, the second network entity 240-2 may determine the identifier list at least based on a query to a UDM or a PCF. For example, the second network entity 240-2 may utilize a gateway mobile location center (GMLC) to query a UDM for the identifier list. Alternatively, the second network entity 240-2 may query the UDM directly for the identifier list.

The second network entity 240-2 may transmit 215 the identifier list and a routing identifier of the second network entity 240-2 to the first network entity 240-1. The first network entity 240-1 may then forward 217 the identifier list and the routing identifier 216 to the first terminal device 220-1 as a response message to the query message 212.

If the response message received from the first network entity 220-1 comprises the identifier list, the first terminal device 220-1 may transmit the broadcast message 203. For example, when a positioning procedure for MO-LR of the first terminal device 220-1 is initiated, the first terminal device 220-1 may transmit a query message to the core network, and the core network may determine whether the location of the first terminal device 220-1 is available. If the location of the first terminal device 220-1 is available in some manners, the core network may provide the location information of the first terminal device 220-1 to the first terminal device 220-1. If the location of the first terminal device 220-1 is unavailable, the core network may transmit a response message comprising the identifier list corresponding to the attribute set list for the sidelink positioning procedure for the first terminal device. The first terminal device 220-1 may then perform a discovery procedure for the sidelink positioning procedure based on the identifier list.

In some implementations, the response message may further comprise a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device. The broadcast message 203 may also comprise the routing identifier. With the indicated routing identifier, the second terminal device 220-2 receiving the broadcast message 203 may be able to query the same second network entity for the identifier matching.

In some embodiments, the first network entity 240-1 may also transmit a report of the first terminal device 220-1 to the second network entity 240-2 so as to assist the second network entity 240-2 to determine the identifier list. The report of the first terminal device may comprise at least one role of the first terminal device during a discovery procedure, e.g., role information of the first terminal device during a discovery process as per 3GPP TS 23.586. Alternatively or additionally, the report of the first terminal device may comprise capability information of the first terminal device, e.g., LCS and ranging capabilities contained in 5GMM capabilities, UE capabilities defined in LPP as per 3GPP TS 37.355, or UE capabilities defined in RSPP/SLPP as per 3GPP TS 33.355. Alternatively or additionally, the report of the first terminal device may comprise status information of the first terminal device, e.g., related UE status information defined in 3GPP TS 38.523. Alternatively or additionally, the report of the first terminal device may comprise environment information of the first terminal device, e.g., NR ECID measurements or runtime QoS context for a SL positioning procedure.

In some embodiments, the first terminal device 220-1 may also transmit a report of the first terminal device 220-1 to the first network entity 240-1 so as to enable the first network entity 240-1 to synchronize the related information of the first terminal device 220-1. The report transmitted from the first terminal device 220-1 to the first network entity 240-1 may comprise at least one role of the first terminal device during a discovery procedure. Alternatively or additionally, the report of the first terminal device may comprise capability information of the first terminal device to be synchronized. Alternatively or additionally, the report of the first terminal device may comprise status information of the first terminal device to be synchronized. Alternatively or additionally, the report of the first terminal device may comprise environment information of the first terminal device to be synchronized. The first network entity 240-1 may then combine or merge the information received from the first terminal device 220-1 and the information of first terminal device 220-1 stored/tracked by the first network entity 240-1.

In some embodiments, the query message 212 may be an uplink (UL) non-access stratum (NAS) TRANSPORT message or a MO-LR message or a supplementary service message. In some embodiments, the query message 212 may be based on a QoS for the SL positioning procedure. For example, in case of the first network entity 240-1 triggers the positioning process, it is the target UE that directly knows the required positioning QoS. The first network entity 240-1 may thus indicates the second network entity 240-2 about the required UE attribute sets satisfying the required positioning QoS in the query message 212.

Turning back to Fig. 2A, in some embodiments, the second terminal device 220-2 may obtain the at least one identifier of at least one attribute set satisfied by the second terminal device 220-2 based on pre-configuration, e.g., from an operator policy. The second terminal device 220-2 may then determine the matching between the identifier list and the at least one pre-configured identifier. Such implementations especially apply for the case where the second terminal device 220-2 is out of coverage.

Alternatively, in order to obtain the at least one identifier, the second terminal device 220-2 may receive the at least one identifier from a first network entity (e.g., an AMF) during a registration procedure of the second terminal device 220-2. In other words, the at least one identifier of at least one attribute set satisfied by the second terminal device 220-2 may be previously received and locally stored in the second terminal device 220-2. The second terminal device 220-2 may then determine the matching between the identifier list and the at least one identifier locally-stored. Such implementations especially apply for the case where the second terminal device 220-2 was initially in coverage but is currently out of coverage.

In an example embodiment, during an initial registration procedure or a periodic registration procedure, the terminal device may be configured with at least one identifier of at least one attribute set satisfied by the terminal device when the terminal device has a ranging &SL positioning capability. For example, the core network (e.g., the AMF) may combine the registration information of the terminal device with subscription data of the terminal device (e.g., obtained by querying the UDM) and reply the allowed identifier list corresponding to the allowed at least one identifier of at least one attribute set satisfied by the second terminal device in a registration accept reply.

In some examples, if the second terminal device 220-2 is in coverage, the second terminal device 220-2 may determine the matching between the identifier list and the at least one identifier with the assistance of the core network. Reference is now made to Fig. 2C, which illustrates a flowchart illustrating a communication process 200C in accordance with some example embodiments of the present disclosure. The communication process 200C may be regarded as a specific example implementation of the step 205 in the process 200A.

For the purpose of discussion, the communication process 200C will be described with reference to Fig. 1. It would be appreciated that although the communication process 200C has been described referring to the network environment 100 of Fig. 1, this communication process 200C may be likewise applied to other similar communication scenarios. The process 200C may involve a second terminal device 220-2, a first network entity 240-1 and a second network entity 240-2. The second terminal device 220-2 may be implemented as any of the terminal devices 120 as illustrated in Fig. 1. The first network entity 240-1 and the second network entity 240-2 may be network elements of the core network 140 as illustrated in Fig. 1. For example, the first network entity 240-1 may be implemented as a control plane entity that manages access and mobility (e.g., a mobility management entity (MME) or an AMF) . The second network entity 240-2 may be implemented as a location server, such as a LMF.

As shown in Fig. 2C, in order to determine whether the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device, the second terminal device 220-2 may transmit 221 a first match query message 222 to the first network entity 240-1. The first match query message 222 may comprise the identifier list, an identifier of the second terminal device and a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device.

The first network entity 240-1 may receive 223 the first match query message 222 and transmit 224 a second match query message 225 to the second network entity 240-2. The second match query message 225 may comprise the identifier list and an identifier of the second terminal device 220-2. In some embodiments, the second match query message 225 may comprise information associated with the first match query message 222 and the identifier of the second terminal device 220-2. In some embodiments, the first match query message 222 may be an UL NAS TRANSPORT message or a MO-LR message or a supplementary service message.

The second network entity 240-2 may receive 226 the second match query message 225 and determine 227 whether the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device. If the identifier list matches the at least one identifier, the second network entity 240-2 may transmit 228 a match response message 229 indicative of the matching to the first network entity 240-1. The first network entity 240-1 may receive 230 the match response message 229 and transmit 231 the match response message 229 to the second terminal device 220-2. The second terminal device 220-2 may receive 232 the match response message 229 and determine whether the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device based on the match response message 229. In this way, a network-assisted discovery procedure is designed.

In some embodiments, the second network entity 240-2 may determine the at least one identifier of the at least one attribute set satisfied by the second terminal device at least based on a query to a UDM or a PCF. For example, the second network entity 240-2 may utilize a GMLC to query a UDM for the at least one identifier. Alternatively, the second network entity 240-2 may query the UDM directly for the at least one identifier.

In some embodiments, the information associated with the first match query message 222 may comprise the identifier list. The first network entity 240-1 may also transmit a report of the second terminal device 220-2 to the second network entity 240-2 so as to assist the second network entity 240-2 to determine the at least one identifier. In some implementations, the second match query message may comprise the report of the second terminal device. The second network entity 240-2 may determine the at least one identifier of the at least one attribute set satisfied by the second terminal device at least based on the match query message.

The report of the second terminal device may comprise at least one role of the second terminal device during a discovery procedure, e.g., role information of the second terminal device during a discovery process as per 3GPP TS 23.586. Alternatively or additionally, the report of the second terminal device may comprise capability information of the second terminal device, e.g., LCS and ranging capabilities contained in 5GMM capabilities, UE capabilities defined in LPP as per 3GPP TS 37.355, or UE capabilities defined in RSPP/SLPP as per 3GPP TS 33.355. Alternatively or additionally, the report of the second terminal device may comprise status information of the second terminal device, e.g., related UE status information defined in 3GPP TS 38.523. Alternatively or additionally, the report of the second terminal device may comprise environment information of the second terminal device, e.g., NR ECID measurements or runtime QoS context for a SL positioning procedure.

In some embodiments, the first network entity 240-1 may determine a subset of identifiers from the identifier list and transmit the second match query message 225 comprising the subset of identifiers to the second network entity 240-2. The subset of identifiers may be determined based on at least one of the following: at least one role of the second terminal device during a discovery procedure; capability information of the second terminal device; status information of the second terminal device; or environment information of the second terminal device.

In some implementations, the second terminal device 220-2 may also transmit a report of the second terminal device 220-2 to the first network entity 240-1 so as to enable the first network entity 240-1 to synchronize the related information of the second terminal device 220-2. The report transmitted from the second terminal device 220-2 to the first network entity 240-1 may comprise at least one role of the second terminal device during a discovery procedure. Alternatively or additionally, the report of the second terminal device may comprise capability information of the second terminal device to be synchronized. Alternatively or additionally, the report of the second terminal device may comprise status information of the second terminal device to be synchronized. Alternatively or additionally, the report of the second terminal device may comprise environment information of the second terminal device to be synchronized. The first network entity 240-1 may then combine or merge the information received from the second terminal device 220-2 and the information of second terminal device 220-2 stored/tracked by the first network entity 240-1.

Turning back to Fig. 2A, if the second terminal device 220-2 determines that the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device 220-2, the second terminal device 220-2 may transmit a response message indicative of the matching to the first terminal device.

In some embodiments, the first terminal device may transmit a message indicative of the matching to the second network entity. The second network entity may then determine whether to select the second terminal device for the sidelink positioning procedure and transmit the determination result to the first terminal device. In one implementation, in order to determine whether to select the second terminal device for the sidelink positioning procedure, the second network entity may transmit, to the first network entity, a request for checking a capability of the second terminal device. The first network entity may determine a subscription of the second terminal device and determine capability information of the second terminal device based on a query to a UDM or a PCF. The first network entity may transmit the subscription and the capability information of the second terminal device to the second network entity. The second network entity may determine whether to select the second terminal device for the sidelink positioning procedure based on the subscription and the capability information of the second terminal device.

In one example implementation, with the process 200A, the first terminal device 220-1 may discover at least one terminal device satisfying at least one identifier matching the identifier list. The first terminal device 220-1 may then report the discovered terminal devices and optionally the respective matched identifiers to the second network entity. The second network entity may then check the concrete capability for reported terminal devices with the first network entity and select the most appropriate terminal devices for the sidelink positioning procedure of the first terminal device.

Fig. 2D illustrates a flowchart illustrating a communication process 200D in accordance with some example embodiments of the present disclosure. The communication process 200D may be regarded as a specific example implementation of the steps 201 and 205 in the process 200A.

For the purpose of discussion, the communication process 200D will be described with reference to Fig. 1. It would be appreciated that although the communication process 200D has been described referring to the network environment 100 of Fig. 1, this communication process 200D may be likewise applied to other similar communication scenarios. The process 200D may involve a first terminal device 220-1, a second terminal device 220-2 and a first network entity 240-1. The first and second terminal device 220-2 may be implemented as any of the terminal devices 120 as illustrated in Fig. 1. The first network entity 240-1 may be a network element of the core network 140 as illustrated in Fig. 1. For example, the first network entity 240-1 may be implemented as a control plane entity that manages access and mobility (e.g., a mobility management entity (MME) or an AMF) .

As shown in Fig. 2C, the first network entity 240-1 may transmit 241, to the first terminal device 220-1, an identifier list 242 corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device 220-1. The first terminal device 220-1 may receive 243 the identifier list 242 and perform subsequent operations in the process 200A. The first network entity 240-1 may transmit 244, to the second terminal device 220-2, at least one identifier 245 of at least one attribute set satisfied by the second terminal device. The second terminal device 220-2 may receive 246 the at least one identifier 245 and perform subsequent operations in the process 200A.

In some embodiments, the identifier list 242 may be transmitted to the first terminal device during a registration procedure of the first terminal device. Alternatively, the first network entity 240-1 may forward, from a second network entity to the first terminal device, a request message for the sidelink positioning procedure, wherein the request message may comprise the identifier list and a routing identifier of the second network entity. Alternatively, the identifier list 242 may be transmitted to the first terminal device 220-1 based on the process 200B as shown in Fig. 2B.

In some embodiments, the at least one identifier 245 may be transmitted to the second terminal device during a registration procedure of the second terminal device. Alternatively, the at least one identifier 245 may be transmitted to the second terminal device 220-2 based on the process 200C as shown in Fig. 2C.

There are three cases for the ranging and sidelink positioning discovery process, namely, an in-coverage case where all related terminal devices are accessible to 5G core network (5GC) over a Uu interface, an out-of-coverage case where relevant terminal devices are not accessible to 5GC, and a partial-coverage case where some of relevant terminal devices are not accessible and some accessible to 5GC. For the purpose of illustration, references are first made to Figs. 3A-3B which illustrates example discovery procedures in an out-of-coverage case and then to Figs. 4A-4C which illustrates example discovery procedures in an in-coverage case to help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. It is to be understood that implementations for the partial-coverage case are also within the scope of the present disclosure.

Fig. 3A illustrates a flowchart illustrating a Model A discovery procedure 300A in an out-of-coverage case in accordance with some example embodiment of the present disclosure. For the purpose of discussion, the communication process 300A will be described with reference to Fig. 1. It would be appreciated that although the communication process 300A has been described referring to the network environment 100 of Fig. 1, this communication process 300A may be likewise applied to other similar communication scenarios. The communication process 300A may be regarded as a specific example implementation of the process 200A of Fig. 2A.

The process 300A may involve a first UE 320-1, a second UE 320-2, a third UE 320-3 and a fourth UE 320-4. The UEs 320-1 to 320-4 may be implemented as any of the UEs 120 as illustrated in Fig. 1. In particular, the UEs 320-1 to 320-4 may be the UE 120-3 or 120-4 and possibly other UEs not shown in Fig. 1 out of coverage range. In the process 300A, the first UE 320-1 serves as a discoverer UE (also referred to as an announcing UE) , and the UEs 320-1 to 320-4 serve as discoveree UEs (also referred to as monitoring UEs) . Throughout the present disclosure, the terms “attribute set” and “discovery profile (DP) ” may be used interchangeably and the terms “an identifier of an attribute set” and “a DP_ID” may be used interchangeably. The discovery profiles may be part of the UE subscription and be identified by discovery profile IDs (DP_IDs) .

In the communication process 300A, the discoverer UE 320-1 may broadcast 302 a ranging &SL positioning announcement message including DP_IDs. The DP_IDs may be associated with discovery profiles for a SL positioning procedure for the discoverer UE 320-1. In some examples, the DP_IDs may be obtained based on the pre-configuration, e.g., from an operator policy. Alternatively, the DP_IDs may be pre-provisioned during a registration procedure. For example, during an initial registration procedure or a periodic registration procedure of the discoverer UE 320-1, if the discoverer UE 320-1 has a ranging &SL positioning capability, the AMF may combine the registration information of the discoverer UE 320-1 with subscription data of the discoverer UE 320-1 (obtained by querying the UDM) and reply the discoverer UE 320-1 with the allowed DP_ID list in a Registration Accept reply.

The discoveree UEs may determine whether DP_IDs in the announcement message match with its pre-configured/pre-provisioned acceptable DP_ID list. The acceptable DP_ID list may be associated with discovery profiles satisfied by the discoveree UEs. In some examples, the acceptable DP_ID list may be obtained based on the pre-configuration, e.g., from an operator policy. Alternatively, the acceptable DP_ID list may be pre-provisioned during a registration procedure. In the example process 300A, the discoveree UE 320-2 determines 304 that DP_IDs in the announcement message match with its pre-configured/pre-provisioned acceptable DP_ID list. The discoveree UE 320-3 determines 306 that DP_IDs in the announcement message match with its pre-configured/pre-provisioned acceptable DP_ID list. The discoveree UE 320-4 determines 308 that DP_IDs in the announcement message match with its pre-configured/pre-provisioned acceptable DP_ID list. Based on such DP_ID matching, theses discoveree UEs may then continue the SL LCS procedure.

Fig. 3B illustrates a flowchart illustrating a Model B discovery procedure 300B in an out-of-coverage case in accordance with some example embodiment of the present disclosure. For the purpose of discussion, the communication process 300B will be described with reference to Fig. 1. It would be appreciated that although the communication process 300B has been described referring to the network environment 100 of Fig. 1, this communication process 300B may be likewise applied to other similar communication scenarios. The communication process 300B may be regarded as a specific example implementation of the process 200A of Fig. 2A.

The process 300B may involve a first UE 320-1, a second UE 320-2, a third UE 320-3 and a fourth UE 320-4. The same reference numerals are used to denote the elements or components described in Fig. 3B having the same operations as the elements or components described in Fig. 3A, and detailed description thereof will be omitted.

In the communication process 300B, the discoverer UE 320-1 may broadcast 312 a ranging &SL positioning solicitation message including DP_IDs. The DP_IDs may be associated with discovery profiles for a SL positioning procedure for the discoverer UE 320-1. In some examples, the DP_IDs may be obtained based on the pre-configuration, e.g., from an operator policy. Alternatively, the DP_IDs may be pre-provisioned during a registration procedure.

The discoveree UEs may determine whether DP_IDs in the solicitation message match with its pre-configured/pre-provisioned acceptable DP_ID list. The acceptable DP_ID list may be associated with discovery profiles satisfied by the discoveree UEs. In some examples, the acceptable DP_ID list may be obtained based on the pre-configuration, e.g., from an operator policy. Alternatively, the acceptable DP_ID list may be pre-provisioned during a registration procedure. In the example process 300B, the discoveree UE 320-2 determines 314 that DP_IDs in the solicitation message match with its pre-configured/pre-provisioned acceptable DP_ID list and transmits 322 a response message indicative of the matching to the discoverer UE 320-1. The discoveree UE 320-3 determines 316 that DP_IDs in the solicitation message match with its pre-configured/pre-provisioned acceptable DP_ID list and transmits 324 a response message indicative of the matching to the discoverer UE 320-1. The discoveree UE 320-4 determines 318 that DP_IDs in the solicitation message do not match with its pre-configured/pre-provisioned acceptable DP_ID list. Based on such determination, the discoveree UE 320-4 does not respond to the solicitation message.

Fig. 4A illustrates a flowchart illustrating a procedure 400A of obtaining DP_IDs in an in-coverage case in accordance with some example embodiment of the present disclosure. For the purpose of discussion, the communication process 400A will be described with reference to Fig. 1. It would be appreciated that although the communication process 400A has been described referring to the network environment 100 of Fig. 1, this communication process 400A may be likewise applied to other similar communication scenarios. The communication process 400A may be regarded as a specific example implementation of the process 200A of Fig. 2A.

The process 400A may involve a discoverer UE 420-1, a serving AMF 440-1 and a serving LMF 440-2 of the discoverer UE 420-1. The discoverer UE 420-1 may be implemented as any of the UEs 120 as illustrated in Fig. 1. In particular, the discoverer UE 420-1 may be the UE 120-1 or 120-2 and possibly other UEs not shown in Fig. 1 in coverage range. The serving AMF 440-1 and the serving LMF 440-2 may be network elements of the core network 140 as illustrated in Fig. 1.

In the communication process 400A, the discoverer UE 420-1 may transmit 401 a DP_ID query message to the serving AMF 440-1. The DP_ID query message may comprise the UE_ID of the discoverer UE 420-1 and the serving cell. The DP_ID query message may be an UL NAS TRANSPORT message, a MO-LR message, or a supplementary service. The UE_ID from the discoverer UE 420-1 may be the Application Layer ID which can be converted to GPSI/SUPI when querying to the UDM. The serving AMF 440-1 may transmit 402 the DP_ID query message to the serving LMF 440-2.

The serving LMF 440-2 may provide the accepted DP_ID (s) for the SL positioning procedure of the discoverer UE 420-1. For example, the serving LMF 440-2 may use the GMLC to query the UDM for the accepted DP_ID (s) . Alternatively, the serving LMF 440-2 may query the UDM directly. The serving LMF 440-2 may transmit 403 the DP_ID query response comprising the accepted DP_ID (s) to the serving AMF 440-1. The serving AMF 440-1 may then forward 404 the DP_ID query response to the discoverer UE 420-1. The discoverer UE 420-1 may then perform 405 a discovery process based on the accepted DP_ID (s) . In this way, the discoverer UE 420-1 may obtain the accepted DP_ID (s) for the SL positioning procedure of the discoverer UE 420-1 from its subscription data in 5GC. The accepted DP_ID (s) for the SL positioning procedure of the discoverer UE may be different for different use cases (e.g., LMF triggered or UE triggered) , different capabilities, different internal status, and different external environment.

In some embodiments, the positioning request may be triggered by the serving LMF 440-2, e.g., in the MT-LR/NI-LR case. In such events, the discoverer UE 420-1 may not need to transmit the DP_ID query message to obtain the accepted DP_ID (s) for the SL positioning procedure. The core network may define the positioning QoS and identify the minimum required capability for reference UEs to be discovered by the discoverer UE. At least one DP_ID may be given to the discoverer UE to discover UEs in this or similar profile class. The discoverer UE may then discovers the UEs (i.e., discoveree UEs) with the given DP_ID and report theses discoveree UEs (and optionally DP_IDs if there a variety of DP_IDs) to the serving LMF 440-2. The serving LMF 440-2 may then check with the serving AMF 440-1 about the concrete capability for reported discoveree UEs and selects the most appropriate discoveree UEs for the SL positioning procedure.

In some embodiments, the positioning request may be triggered by the discoverer UE 420-1. In such events, the discoverer UE 420-1 know directly the required positioning QoS. The discoverer UE 420-1 may thus (optionally) notify the serving LMF 440-2 on the required DP_IDs for the SL positioning procedure. Then, a selective profile-driven discovery follows as in the MT-LR/NI-LR case, followed by a selection of discoveree UEs based on the collaboration of LMF and AMF.

With an integrated view in 5GC, the LMF is able to perform the permission /filtering /selection of both discoverer and discoveree UE instances, avoid unnecessary discovery signaling, optimize the UE roles in the ranging &SL procedures and optimize the ranging &SL procedures.

The discovery profiles may be part of the UE subscription and may be identified by DP_IDs. Each UE may be provisioned with multiple DP_IDs and include the list of DP_IDs in discovery announcing and response messages. For the in-coverage case, the discovery process may use the DP_IDs from the subscription data of the UE in 5GC. For example, the in-coverage discoverer UE may query its serving LMF for the accepted /allowed /filtered subset of the DP_IDs in the discovery announcing. The DP_IDs correspond to discovery profile for SL positioning of the discoverer UE. The discoveree UEs may consult the network (via the LMF or via the AMF) on specific details of particular discovery profiles or DP_IDs to determine whether it satisfies discovery profiles matching the allowed DP_IDs of the discoverer UE. For example, the in-coverage discoveree UE may query the same LMF instance by using the routing ID of the LMF serving the discoverer UE and then process the announce message.

In other words, both the discoverer UE and the discoveree UEs use the same LMF instance by using the same routing ID. The discoverer UE may use its own serving LMF’s routing ID in a NAS message. Alternatively, the discoverer UE may use the routing ID instructed by AMF/LMF at step 404 in Fig. 4A. The discoverer UE may then transmit the routing ID in a discovery broadcast message (e.g., an announcing message in Model A, or a solicitation message in Model B) . The discoveree UE then utilizes the routing ID in the broadcast message to access the same LMF instance of the discoverer UE.

Fig. 4B illustrates a flowchart illustrating a Model A discovery procedure 405A with discovery profiles in an in-coverage case in accordance with some example embodiment of the present disclosure. For the purpose of discussion, the communication process 405A will be described with reference to Fig. 1. It would be appreciated that although the communication process 405A has been described referring to the network environment 100 of Fig. 1, this communication process 405A may be likewise applied to other similar communication scenarios. The communication process 405A may be regarded as a specific example implementation of the step 405 in the process 400 of Fig. 4A or the step 205 in the process 200A of Fig. 2A.

The process 405A may involve a discoverer UE 420-1, a discoveree UE 420-2, a serving AMF 440-1 and a serving LMF 440-2 of the discoverer UE 420-1. The discoveree UE 420-2 may be implemented as any of the UEs 120 as illustrated in Fig. 1. In particular, the discoveree UE 420-2 may be the UE 120-1 or 120-2 and possibly other UEs not shown in Fig. 1 in coverage range. The same reference numerals are used to denote the elements or components described in Fig. 4B having the same operations as the elements or components described in Fig. 4A, and detailed description thereof will be omitted.

In the communication process 405A, the discoverer UE 420-1 may broadcast 411 a ranging &SL positioning announcement message including DP_IDs and a routing ID associated with the serving LMF 440-2 of the discoverer UE 420-1. The DP_IDs may be associated with discovery profiles for a SL positioning procedure for the discoverer UE 420-1. For example, the DP_IDs may correspond to the DP_IDs in the DP_ID query response message in the process 400 in Fig. 4A and may be determined by the LMF 440-2. The discoveree UE 420-2 receiving the announcement message may transmit 412 a DP_ID match query message to the serving AMF 440-1. The DP_ID match query message may comprise the UE_ID of the discoveree UE 420-2, the serving cell and contents in the announcement message including DP_IDs and the routing ID.

The serving AMF 440-1 may transmit 413 the DP_ID match query message to the serving LMF 440-2 based on the routing ID. The serving LMF 440-2 may determine whether the discoveree UE 420-2 satisfies discovery profiles with DP_IDs that match the DP_IDs in the DP_ID match query message. If yes, the serving LMF 440-2 may transmit 414 the DP_ID match query response message comprising the matched DP_IDs to the serving AMF 440-1. The serving AMF 440-1 may forward the DP_ID match query response message to the discoveree UE 420-2. The discoveree UE 420-2 may thus determine that there is a match between the DP_IDs in the broadcast message received from the discoverer UE 420-1 and the DP_IDs corresponding to discovery profiles satisfied by the discoveree UE 420-2.

If the serving LMF 440-2 determines DP_IDs in the broadcast message received from the discoverer UE 420-1 do not correspond to discovery profiles satisfied by the discoveree UE 420-2, the serving LMF 440-2 may transmit 414 the DP_ID match query response message comprising an indication of no matching to the serving AMF 440-1. The serving AMF 440-1 may forward the DP_ID match query response message to the discoveree UE 420-2. The discoveree UE 420-2 may thus determine that there is no match between the DP_IDs in the broadcast message received from the discoverer UE 420-1 and the DP_IDs corresponding to discovery profiles satisfied by the discoveree UE 420-2.

Fig. 4C illustrates a flowchart illustrating a Model B discovery procedure 405B with discovery profiles in an in-coverage case in accordance with some example embodiment of the present disclosure. For the purpose of discussion, the communication process 405B will be described with reference to Fig. 1. It would be appreciated that although the communication process 405B has been described referring to the network environment 100 of Fig. 1, this communication process 405B may be likewise applied to other similar communication scenarios. The communication process 405B may be regarded as a specific example implementation of the step 405 in the process 400 of Fig. 4A or the step 205 in the process 200A of Fig. 2A.

The process 405B may involve a discoverer UE 420-1, a discoveree UE 420-2, a serving AMF 440-1 and a serving LMF 440-2 of the discoverer UE 420-1. The same reference numerals are used to denote the elements or components described in Fig. 4C having the same operations as the elements or components described in Figs. 4A and 4B, and detailed description thereof will be omitted.

The process 405B differs from the process 405A in that the discoverer UE 420-1 broadcasts 421 a solicitation message in the process 405B and the discoveree UE transmits 426 a response message based on the DP_ID match query response message. If discoveree UE 420-2 determines that there is no match between the DP_IDs in the broadcast message received from the discoverer UE 420-1 and the DP_IDs corresponding to discovery profiles satisfied by the discoveree UE 420-2, the discoveree UE 420-2 would not respond to the solicitation message. If the discoveree UE 420-2 determines that there is a match between the DP_IDs in the broadcast message received from the discoverer UE 420-1 and the DP_IDs corresponding to discovery profiles satisfied by the discoveree UE 420-2, the discoveree UE 420-2 would transmit 426 a response message indicative of the matching to the discoverer UE 420-1.

It should be noted that a located UE may be considered as in-coverage or accessible to 5GC (directly or through a relay UE, etc. ) . The procedure 400 in Fig. 4A may also apply to a located UE when it becomes a new discoverer UE to update its location. The ripple effect can be alleviated or eliminated by assigning the same routing ID of the original serving LMF of original discoverer UE to the discoveree UEs. Then, the original serving LMF has the overall/complete view of all located UEs and the discoverer UE to address the ripple effect.

According to some embodiments of the present disclosure, considering to the different capabilities required in different procedures, the so-called “discovery profiles” or “attribute sets” are designed to streamline the discovery process in Ranging &SL and make it more selective and accurate. Different levels of positioning QoS are associated with specific minimum capability requirements and associated with different attribute sets. In an example implementation, an identifier corresponding to an attribute set (or a DP_ID) may be given to the discoverer UE for selective discovery of UEs satisfying such attribute set. The discoverer UE may then discover UEs with the given “identifier/DP_ID” and report them to the LMF. The LMF may then check with the AMF about the concrete capability for reported UEs. The AMF may then further query subscription of these UEs and/or query PCF for related roles and capabilities of these UEs.

In accordance with some example embodiments of the present disclosure, when AMF/LMF is involved, the discovery procedure could be defined as a network assisted discovery and 3GPP TS 23.273 may be enhanced.

Fig. 5A illustrates a flowchart illustrating a procedure for SL-MO-LR in accordance with some example embodiment of the present disclosure. In particular, Fig. 5A illustrates an enhancement to the procedure of SL-MO-LR as defined in Figure 6.20.1-1 in clause 6.20.1 in 3GPP TS 23.273. Clause 6.20.1 in 3GPP TS 23.273 may be updated as follows:

Fig. 5B illustrates a flowchart illustrating a procedure for SL-MT-LR in accordance with some example embodiment of the present disclosure. In particular, Fig. 5B illustrates an enhancement to the procedure of SL-MT-LR as defined in Figure 6.20.3-1 in clause 6.20.3 in 3GPP TS 23.273. Clause 6.20.3 in 3GPP TS 23.273 may be updated as follows:

Fig. 5C illustrates a flowchart illustrating a procedure for SL-MT-LR for periodic, triggered location events in accordance with some example embodiment of the present disclosure. In particular, Fig. 5B illustrates an enhancement to the procedure of SL-MT-LR for periodic, triggered location events as defined in Figure 6.20.4-1 in clause 6.20.4 in 3GPP TS 23.273. Clause 6.20.4 in 3GPP TS 23.273 may be updated as follows:

Fig. 6 illustrates a flowchart of an example method 600 implemented at a first terminal device in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 600 will be described from the perspective of the first terminal device 220-1 with reference to Figs. 2A-2D.

At block 610, the first terminal device 220-1 obtains an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device. At block 620, the first terminal device 220-1 transmits, during a discovery procedure for the sidelink positioning procedure, a broadcast message comprising the identifier list.

In some example embodiments, in order to obtain the identifier list, the first terminal device 220-1 may receive the identifier list from a first network entity during a registration procedure of the first terminal device. Alternatively, the first terminal device 220-1 may obtain the identifier list based on pre-configuration.

In some example embodiments, in order to obtain the identifier list, the first terminal device 220-1 may receive a request message for the sidelink positioning procedure, wherein the request message comprises the identifier list and a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device, wherein the first terminal device is caused to transmit the broadcast message based on determining that the request message is received.

In some example embodiments, in order to obtain the identifier list, the first terminal device 220-1 may transmit, to a first network entity, a query message comprising an identifier of the first terminal device; and receive, from the first network entity, a response message comprising the identifier list and a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device. The first terminal device 220-1 may further transmit the broadcast message based on determining that the response message comprising the identifier list is received from the first network entity.

In some example embodiments, the query message may be one of the following: an uplink (UL) non-access stratum (NAS) TRANSPORT message; a mobile-originated location request (MO-LR) message; or a supplementary service message. In some example embodiments, the query message may be based on a quality of service (QoS) for the sidelink positioning procedure.

In some example embodiments, the query message may further comprise at least one of the following: at least one role of the first terminal device during the discovery procedure; capability information of the first terminal device to be synchronized; status information of the first terminal device to be synchronized; or environment information of the first terminal device to be synchronized. In some example embodiments, the broadcast message may further comprise a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device.

In some example embodiments, the first terminal device 220-1 may further receive, from a second terminal device, a response message indicative of matching between the identifier list and at least one identifier of at least one attribute set satisfied by the second terminal device.

In some example embodiments, the first terminal device 220-1 may further transmit, to a second network entity, a message indicative of the matching; and receive, from the second network entity, an indication of whether to select the second terminal device for the sidelink positioning procedure.

In some example embodiments, an attribute set in the attribute set list comprises at least one of the following: a type of a location request; at least one role of a terminal device during the discovery procedure; capability information of the terminal device; status information of the terminal device; or environment information of the terminal device.

In some example embodiments, the capability information comprises at least one of the following: at least one location services (LCS) and ranging capability; or at least one capability defined in at least one of a long term evolution (LTE) positioning protocol (LPP) or a ranging/sidelink positioning protocol (RSPP/SLPP) .

In some example embodiments, the environment information comprises at least one enhanced cell identified (ECID) measurement or at least one runtime QoS context for the sidelink positioning procedure. In some example embodiments, the first network entity is an access and mobility management function (AMF) . In some example embodiments, the second network entity is a location management function (LMF) .

Fig. 7 illustrates another flowchart of an example method 700 implemented at a network device in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 500 will be described from the perspective of the second terminal device 220-2 with reference to Figs. 2A-2D.

At block 710, the second terminal device 220-2 receives, from a first terminal device, a broadcast message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device. At block 720, the second terminal device 220-2 determines whether the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device.

In some example embodiments, the second terminal device 220-2 may further receive, during a registration procedure of the second terminal device, the at least one identifier from a first network entity. Alternatively, the second terminal device 220-2 may further obtain the at least one identifier based on pre-configuration.

In some example embodiments, the broadcast message further comprises a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device.

In some example embodiments, in order to determine whether the identifier list matches the at least one identifier, the second terminal device 220-2 may transmit, to a first network entity, a match query message comprising the identifier list, an identifier of the second terminal device and the routing identifier of the second network entity; and receive, from the first network entity, a match response message indicative of matching between the identifier list and the at least one identifier of the at least one attribute set satisfied by the second terminal device.

In some example embodiments, the match query message is one of the following: an uplink (UL) non-access stratum (NAS) TRANSPORT message; a mobile-originated location request (MO-LR) message; or a supplementary service message.

In some example embodiments, the match query message further comprises at least one of the following: at least one role of the second terminal device during a discovery procedure; capability information of the second terminal device to be synchronized; status information of the second terminal device to be synchronized; or environment information of the second terminal device to be synchronized.

In some example embodiments, based on determining that the identifier list matches the at least one identifier, the second terminal device 220-2 may further transmit, to the first terminal device, a response message indicative of matching between the identifier list and the at least one identifier of the at least one attribute set satisfied by the second terminal device.

In some example embodiments, an attribute set in the attribute set list or the at least one attribute set comprises at least one of the following: a type of a location request; at least one role of a terminal device during the discovery procedure; capability information of the terminal device; status information of the terminal device; or environment information of the terminal device.

Fig. 8 illustrates another flowchart of an example method 800 implemented at a network device in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 800 will be described from the perspective of the first network entity 240-1 with reference to Figs. 2A-2D.

At block 810, the first network entity 240-1 transmits, to a first terminal device, an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device. At block 820, the first network entity 240-1 transmits, to a second terminal device, at least one identifier of at least one attribute set satisfied by the second terminal device.

In some example embodiments, the identifier list is transmitted to the first terminal device during a registration procedure of the first terminal device. In some example embodiments, in order to transmit the identifier list, the first network entity 240-1 may receive, from a second network entity, a request message for the sidelink positioning procedure, wherein the request message comprises the identifier list and a routing identifier of the second network entity; and transmit, to the first terminal device, the request message.

In some example embodiments, in order to transmit the identifier list, the first network entity 240-1 may receive, from the first terminal device, a query message comprising an identifier of the first terminal device; transmit, to a second network entity, the query message; receive, from the second network entity, the identifier list and a routing identifier of the second network entity; and transmit, to the first terminal device, the identifier list and the routing identifier.

In some example embodiments, the first network entity 240-1 may further transmit, to the second network entity, a report of the first terminal device, wherein the report comprises at least one of the following: at least one role of the first terminal device during a discovery procedure; capability information of the first terminal device; status information of the first terminal device; or environment information of the first terminal device.

In some example embodiments, the query message is one of the following: an uplink (UL) non-access stratum (NAS) TRANSPORT message; a mobile-originated location request (MO-LR) message; or a supplementary service message. In some example embodiments, the query message is based on a quality of service (QoS) for the sidelink positioning procedure.

In some example embodiments, the query message further comprises at least one of the following: at least one role of the first terminal device during the discovery procedure; capability information of the first terminal device to be synchronized; status information of the first terminal device to be synchronized; or environment information of the first terminal device to be synchronized. In some example embodiments, the at least one identifier is transmitted to the second terminal device during a registration procedure of the second terminal device.

In some example embodiments, the first network entity 240-1 may further receive, from the second terminal device, a first match query message comprising the identifier list, an identifier of the second terminal device, and a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device; transmit, to the second network entity, a second match query message comprising information associated with the first match query message and an identifier of the second terminal device; and receive, from the second network entity, a match response message indicative of matching between the identifier list and the at least one identifier of at least one attribute set satisfied by the second terminal device.

In some example embodiments, the information associated with the first match query message comprises the identifier list, the second match query message further comprises a report of the second terminal device, wherein the report comprises at least one of the following: at least one role of the second terminal device during a discovery procedure; capability information of the second terminal device; status information of the second terminal device; or environment information of the second terminal device.

In some example embodiments, the first network entity 240-1 may further determine a subset of identifiers from the identifier list based on at least one of the following: at least one role of the second terminal device during a discovery procedure; capability information of the second terminal device; status information of the second terminal device; or environment information of the second terminal device, wherein the information associated with the first match query message comprises the subset of identifiers.

In some example embodiments, the first match query message further comprises at least one of the following: at least one role of the second terminal device during a discovery procedure; capability information of the second terminal device to be synchronized; status information of the second terminal device to be synchronized; or environment information of the second terminal device to be synchronized.

In some example embodiments, the first match query message is one of the following: an uplink (UL) non-access stratum (NAS) TRANSPORT message; a mobile-originated location request (MO-LR) message; or a supplementary service message.

In some example embodiments, an attribute set among the attribute set list or the at least one attribute set comprises at least one of the following: a type of a location request; at least one role of a terminal device during the discovery procedure; capability information of the terminal device; status information of the terminal device; or environment information of the terminal device.

In some example embodiments, the environment information comprises at least one enhanced cell identified (ECID) measurement or at least one runtime QoS context for the sidelink positioning procedure.

In some example embodiments, the first network entity 240-1 may further receive, from a second network entity, a request for checking a capability of the second terminal device; determine a subscription of the second terminal device; determine capability information of the second terminal device based on a query to a unified data management function (UDM) or a policy control function (PCF) ; and transmit, to the second network entity, the subscription and the capability information of the second terminal device.

In some example embodiments, the first network entity is an access and mobility management function (AMF) . In some example embodiments, the second network entity is a location management function (LMF) .

Fig. 9 illustrates another flowchart of an example method 900 implemented at a network device in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 900 will be described from the perspective of the second network entity 240-2 with reference to Figs. 2A-2D.

At block 910, the second network entity 240-2 receives, from a first network entity, a match query message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for a first terminal device and an identifier of the second terminal device. At block 920, the second network entity 240-2 transmits, to the first network entity, a message indicative of matching between the identifier list and the at least one identifier based on determining that the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device.

In some example embodiments, the match query message further comprises a report of the second terminal device. The second network entity 240-2 may further determine the at least one identifier of the at least one attribute set satisfied by the second terminal device at least based on the match query message. The report comprises at least one of the following: at least one role of the second terminal device during a discovery procedure; capability information of the second terminal device; status information of the second terminal device; or environment information of the second terminal device.

In some example embodiments, the second network entity 240-2 may further determine the at least one identifier of the at least one attribute set satisfied by the second terminal device at least based on a query to a unified data management function (UDM) or a Policy Control Function (PCF) . In some example embodiments, the second network entity 240-2 may further transmit, to the first terminal device, a request message for the sidelink positioning procedure, wherein the request message comprises the identifier list and a routing identifier of the second network entity.

In some example embodiments, the second network entity 240-2 may further receive, from the first network entity, a query message comprising an identifier of the first terminal device; determine the identifier list; and transmit the identifier list and a routing identifier of the second network entity to the first network entity.

In some example embodiments, the second network entity 240-2 may further receive, from the first network entity, a report of the first terminal device, wherein the identifier list is determined at least based on the report of the first terminal device, wherein the report comprises at least one of the following: at least one role of the first terminal device during a discovery procedure; capability information of the first terminal device; status information of the first terminal device; or environment information of the first terminal device.

In some example embodiments, the identifier list is determined at least based on a query to a UDM/PCF. In some example embodiments, the second network entity 240-2 may further receive, from the first terminal device, a message indicative of the matching; and transmit, to the first terminal device, an indication of whether to select the second terminal device for the sidelink positioning procedure.

In some example embodiments, the second network entity 240-2 may further transmit, to the first network entity, a request for checking a capability of the second terminal device; receive, from the first the second network entity, the subscription and the capability information of the second terminal device; and determine whether to select the second terminal device for the sidelink positioning procedure.

In some example embodiments, the environment information comprises at least one enhanced cell identified (ECID) measurement or at least one runtime QoS context for the sidelink positioning procedure. In some example embodiments, the first network entity is an access and mobility management function (AMF) , and the second network entity is a location management function (LMF) .

In some example embodiments, an apparatus capable of performing the method 600 (for example, the first terminal device 220-1) may comprise means for performing the respective steps of the method 600. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some example embodiments, the apparatus comprises: means for obtaining an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and means for transmitting, during a discovery procedure for the sidelink positioning procedure, a broadcast message comprising the identifier list.

In some example embodiments, the means for obtaining the identifier list may comprise means for receiving, during a registration procedure of the first terminal device, the identifier list from a first network entity. In some example embodiments, the means for obtaining the identifier list may comprise means for obtaining the identifier list by pre-configuration.

In some example embodiments, the means for obtaining the identifier list may comprise means for receiving a request message for the sidelink positioning procedure, wherein the request message comprises the identifier list and a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device; wherein the first terminal device is caused to transmit the broadcast message based on determining that the request message is received.

In some example embodiments, the means for obtaining the identifier list may comprise means for transmitting, to a first network entity, a query message comprising an identifier of the first terminal device; and means for receiving, from the first network entity, a response message comprising the identifier list and a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device; wherein the first terminal device is caused to transmit the broadcast message based on determining that the response message comprising the identifier list is received from the first network entity.

In some example embodiments, the query message further comprises at least one of the following: at least one role of the first terminal device during the discovery procedure; capability information of the first terminal device to be synchronized; status information of the first terminal device to be synchronized; or environment information of the first terminal device to be synchronized.

In some example embodiments, the broadcast message further comprises a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device. In some example embodiments, the apparatus may further comprise means for receiving, from a second terminal device, a response message indicative of matching between the identifier list and at least one identifier of at least one attribute set satisfied by the second terminal device.

In some example embodiments, the apparatus may further comprise means for transmitting, to a second network entity, a message indicative of the matching; and means for receiving, from the second network entity, an indication of whether to select the second terminal device for the sidelink positioning procedure.

In some example embodiments, the apparatus further comprises means for performing other steps in some example embodiments of the method 600. In some example embodiments, the means comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the performance of the apparatus.

In some example embodiments, an apparatus capable of performing the method 700 (for example, the second terminal device 220-2) may comprise means for performing the respective steps of the method 700. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some example embodiments, the apparatus comprises: means for receiving, from a first terminal device, a broadcast message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and means for determining whether the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device.

In some example embodiments, the apparatus may further comprise means for receiving, during a registration procedure of the second terminal device, the at least one identifier from a first network entity; or means for obtaining the at least one identifier based on pre-configuration. In some example embodiments, the broadcast message further comprises a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device.

In some example embodiments, the means for determining whether the identifier list matches the at least one identifier comprises: means for transmitting, to a first network entity, a match query message comprising the identifier list, an identifier of the second terminal device and the routing identifier of the second network entity; and means for receiving, from the first network entity, a match response message indicative of matching between the identifier list and the at least one identifier of the at least one attribute set satisfied by the second terminal device.

In some example embodiments, the match query message is one of the following: an uplink (UL) non-access stratum (NAS) TRANSPORT message; a mobile-originated location request (MO-LR) message; or a supplementary service message. In some example embodiments, the match query message further comprises at least one of the following: at least one role of the second terminal device during a discovery procedure; capability information of the second terminal device to be synchronized; status information of the second terminal device to be synchronized; or environment information of the second terminal device to be synchronized.

In some example embodiments, the apparatus may further comprise means for: based on determining that the identifier list matches the at least one identifier, transmitting, to the first terminal device, a response message indicative of matching between the identifier list and the at least one identifier of the at least one attribute set satisfied by the second terminal device.

In some example embodiments, the apparatus further comprises means for performing other steps in some example embodiments of the method 700. In some example embodiments, the means comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the performance of the apparatus.

In some example embodiments, an apparatus capable of performing the method 800 (for example, the first network entity 240-1) may comprise means for performing the respective steps of the method 800. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some example embodiments, the apparatus comprises: means for transmitting, to a first terminal device, an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and means for transmitting, to a second terminal device, at least one identifier of at least one attribute set satisfied by the second terminal device.

In some example embodiments, the identifier list is transmitted to the first terminal device during a registration procedure of the first terminal device. In some example embodiments, the means for transmitting the identifier list comprises: means for receiving, from a second network entity, a request message for the sidelink positioning procedure, wherein the request message comprises the identifier list and a routing identifier of the second network entity; and means for transmitting, to the first terminal device, the request message.

In some example embodiments, the means for transmitting the identifier list comprises: means for receiving, from the first terminal device, a query message comprising an identifier of the first terminal device; means for transmitting, to a second network entity, the query message; means for receiving, from the second network entity, the identifier list and a routing identifier of the second network entity; and means for transmitting, to the first terminal device, the identifier list and the routing identifier.

In some example embodiments, the apparatus may further comprise means for transmitting, to the second network entity, a report of the first terminal device, wherein the report comprises at least one of the following: at least one role of the first terminal device during a discovery procedure; capability information of the first terminal device; status information of the first terminal device; or environment information of the first terminal device.

In some example embodiments, the apparatus may further comprise means for receiving, from the second terminal device, a first match query message comprising the identifier list, an identifier of the second terminal device, and a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device; means for transmitting, to the second network entity, a second match query message comprising information associated with the first match query message and an identifier of the second terminal device; and means for receiving, from the second network entity, a match response message indicative of matching between the identifier list and the at least one identifier of at least one attribute set satisfied by the second terminal device.

In some example embodiments, the apparatus may further comprise means for determining a subset of identifiers from the identifier list based on at least one of the following: at least one role of the second terminal device during a discovery procedure; capability information of the second terminal device; status information of the second terminal device; or environment information of the second terminal device, wherein the information associated with the first match query message comprises the subset of identifiers.

In some example embodiments, the apparatus may further comprise means for receiving, from a second network entity, a request for checking a capability of the second terminal device; means for determining a subscription of the second terminal device; means for determining capability information of the second terminal device based on a query to a unified data management function (UDM) or a policy control function (PCF) ; and means for transmitting, to the second network entity, the subscription and the capability information of the second terminal device.

In some example embodiments, the apparatus further comprises means for performing other steps in some example embodiments of the method 800. In some example embodiments, the means comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the performance of the apparatus.

In some example embodiments, an apparatus capable of performing the method 900 (for example, the second network entity 240-2) may comprise means for performing the respective steps of the method 900. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some example embodiments, the apparatus comprises: means for receiving, from a first network entity, a match query message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for a first terminal device and an identifier of the second terminal device; and means for based on determining that the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device, transmitting, to the first network entity, a message indicative of matching between the identifier list and the at least one identifier.

In some example embodiments, the match query message further comprises a report of the second terminal device. The apparatus may further comprise means for determining the at least one identifier of the at least one attribute set satisfied by the second terminal device at least based on the match query message. The report comprises at least one of the following: at least one role of the second terminal device during a discovery procedure; capability information of the second terminal device; status information of the second terminal device; or environment information of the second terminal device.

In some example embodiments, the apparatus may further comprise means for determining the at least one identifier of the at least one attribute set satisfied by the second terminal device at least based on a query to a unified data management function (UDM) or a Policy Control Function (PCF) .

In some example embodiments, the apparatus may further comprise means for transmitting, to the first terminal device, a request message for the sidelink positioning procedure, wherein the request message comprises the identifier list and a routing identifier of the second network entity.

In some example embodiments, the apparatus may further comprise means for receiving, from the first network entity, a query message comprising an identifier of the first terminal device; means for determining the identifier list; and means for transmitting the identifier list and a routing identifier of the second network entity to the first network entity.

In some example embodiments, the apparatus may further comprise means for receiving, from the first network entity, a report of the first terminal device. The identifier list is determined at least based on the report of the first terminal device, wherein the report comprises at least one of the following: at least one role of the first terminal device during a discovery procedure; capability information of the first terminal device; status information of the first terminal device; or environment information of the first terminal device.

In some example embodiments, the identifier list is determined at least based on a query to a UDM/PCF. In some example embodiments, the apparatus may further comprise means for receiving, from the first terminal device, a message indicative of the matching; and means for transmitting, to the first terminal device, an indication of whether to select the second terminal device for the sidelink positioning procedure.

In some example embodiments, the apparatus may further comprise means for transmitting, to the first network entity, a request for checking a capability of the second terminal device; means for receiving, from the first the second network entity, the subscription and the capability information of the second terminal device; and means for determining whether to select the second terminal device for the sidelink positioning procedure.

In some example embodiments, the apparatus further comprises means for performing other steps in some example embodiments of the method 900. In some example embodiments, the means comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the performance of the apparatus.

Fig. 10 illustrates a simplified block diagram of a device 1000 that is suitable for implementing some example embodiments of the present disclosure. The device 1000 may be provided to implement a communication device, for example, the first terminal device 220-1, the second terminal device 220-2, the first network entity 240-1 or the second network entity 240-2 as shown in Figs. 2A-2D. As shown, the device 1000 includes one or more processors 1010, one or more memories 1020 coupled to the processor 1010, and one or more communication modules 1040 coupled to the processor 1010.

The communication module 1040 is for bidirectional communications. The communication module 1040 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements.

The processor 1010 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1000 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

The memory 1020 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 1024, an electrically programmable read only memory (EPROM) , a flash memory, a hard disk, a compact disc (CD) , a digital video disk (DVD) , and other magnetic storage and/or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 1022 and other volatile memories that will not last in the power-down duration.

A computer program 1030 includes computer executable instructions that are executed by the associated processor 1010. The program 1030 may be stored in the ROM 1024. The processor 1010 may perform any suitable actions and processing by loading the program 1030 into the RAM 1022.

The embodiments of the present disclosure may be implemented by means of the program 1030 so that the device 1000 may perform any process of the disclosure as discussed with reference to Figs. 2A-2D. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

In some example embodiments, the program 1030 may be tangibly contained in a computer-readable medium which may be included in the device 1000 (such as in the memory 1020) or other storage devices that are accessible by the device 1000. The device 1000 may load the program 1030 from the computer-readable medium to the RAM 1022 for execution. The computer-readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like.

Fig. 11 illustrates a block diagram of an example of a computer-readable medium 1000 in accordance with some example embodiments of the present disclosure. The computer-readable medium 1100 has the program 1030 stored thereon. It is noted that although the computer-readable medium 1100 is depicted in form of CD or DVD in Fig. 11, the computer-readable medium 1100 may be in any other form suitable for carry or hold the program 1030.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects 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. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method 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.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the method 600, 700, 800 or 900 as described above with reference to Fig. 6, 7, 8 or 9. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of the present disclosure, the computer program codes or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer-readable medium, and the like.

The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. A computer-readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer-readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. 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) .

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in languages specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

A first terminal device comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to:

obtain an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and

transmit, during a discovery procedure for the sidelink positioning procedure, a broadcast message comprising the identifier list.
The first terminal device of claim 1, wherein the first terminal device is caused to obtain the identifier list by:

receiving, during a registration procedure of the first terminal device, the identifier list from a first network entity; or

pre-configuration.
The first terminal device of claim 1, wherein the first terminal device is caused to obtain the identifier list by:

receiving a request message for the sidelink positioning procedure, wherein the request message comprises the identifier list and a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device;

wherein the first terminal device is caused to transmit the broadcast message based on determining that the request message is received.
The first terminal device of claim 1, wherein the first terminal device is caused to obtain the identifier list by:

transmitting, to a first network entity, a query message comprising an identifier of the first terminal device; and

receiving, from the first network entity, a response message comprising the identifier list and a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device;

wherein the first terminal device is caused to transmit the broadcast message based on determining that the response message comprising the identifier list is received from the first network entity.
The first terminal device of claim 4, wherein the query message is one of the following:

an uplink (UL) non-access stratum (NAS) TRANSPORT message;

a mobile-originated location request (MO-LR) message; or

a supplementary service message.
The first terminal device of claim 4 or 5, wherein the query message is based on a quality of service (QoS) for the sidelink positioning procedure.
The first terminal device of any of claims 4-6, wherein the query message further comprises at least one of the following:

at least one role of the first terminal device during the discovery procedure;

capability information of the first terminal device to be synchronized;

status information of the first terminal device to be synchronized; or

environment information of the first terminal device to be synchronized.
The first terminal device of any of claims 1-7, wherein the broadcast message further comprises a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device.
The first terminal device of any of claims 1-8, wherein the first terminal device is further caused to:

receive, from a second terminal device, a response message indicative of matching between the identifier list and at least one identifier of at least one attribute set satisfied by the second terminal device.
The first terminal device of claim 9, wherein the first terminal device is further caused to:

transmit, to a second network entity, a message indicative of the matching; and

receive, from the second network entity, an indication of whether to select the second terminal device for the sidelink positioning procedure.
The first terminal device of any of claims 1-10, wherein an attribute set in the attribute set list comprises at least one of the following:

a type of a location request;

at least one role of a terminal device during the discovery procedure;

capability information of the terminal device;

status information of the terminal device; or

environment information of the terminal device.
The first terminal device of claim 7 or 11, wherein the capability information comprises at least one of the following:

at least one location services (LCS) and ranging capability; or

at least one capability defined in at least one of a long term evolution (LTE) positioning protocol (LPP) or a ranging/sidelink positioning protocol (RSPP/SLPP) .
The first terminal device of claims 7 or 11, wherein the environment information comprises at least one enhanced cell identified (ECID) measurement or at least one runtime QoS context for the sidelink positioning procedure.
The first terminal device of any of claims 2 or 4, wherein the first network entity is an access and mobility management function (AMF) .
The first terminal device of claim 8 or 10, wherein the second network entity is a location management function (LMF) .
A second terminal device comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to:

receive, from a first terminal device, a broadcast message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and

determine whether the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device.
The second terminal device of claim 16, wherein the second terminal device is further caused to:

receive, during a registration procedure of the second terminal device, the at least one identifier from a first network entity; or

obtain the at least one identifier based on pre-configuration.
The second terminal device of claim 16, wherein the broadcast message further comprises a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device.
The second terminal device of claim 18, wherein the second terminal device is caused to determine whether the identifier list matches the at least one identifier by:

transmitting, to a first network entity, a match query message comprising the identifier list, an identifier of the second terminal device and the routing identifier of the second network entity; and

receiving, from the first network entity, a match response message indicative of matching between the identifier list and the at least one identifier of the at least one attribute set satisfied by the second terminal device.
The second terminal device of claim 19, wherein the match query message is one of the following:

an uplink (UL) non-access stratum (NAS) TRANSPORT message;

a mobile-originated location request (MO-LR) message; or

a supplementary service message.
The second terminal device of claim 19 or 20, wherein the match query message further comprises at least one of the following:

at least one role of the second terminal device during a discovery procedure;

capability information of the second terminal device to be synchronized;

status information of the second terminal device to be synchronized; or

environment information of the second terminal device to be synchronized.
The second terminal device of any of claims 15-21, wherein second terminal device is further caused to:

based on determining that the identifier list matches the at least one identifier, transmit, to the first terminal device, a response message indicative of matching between the identifier list and the at least one identifier of the at least one attribute set satisfied by the second terminal device.
The second terminal device of any of claims 15-22, wherein an attribute set in the attribute set list or the at least one attribute set comprises at least one of the following:

a type of a location request;

at least one role of a terminal device during the discovery procedure;

capability information of the terminal device;

status information of the terminal device; or

environment information of the terminal device.
The second terminal device of claim 21 or 23, wherein the capability information comprises at least one of the following:

at least one location services (LCS) and ranging capability; or

at least one capability defined in at least one of a long term evolution (LTE) positioning protocol (LPP) or a ranging/sidelink positioning protocol (RSPP/SLPP) .
The second terminal device of claim 21 or 23, wherein the environment information comprises at least one enhanced cell identified (ECID) measurement or at least one runtime QoS context for the sidelink positioning procedure.
The second terminal device of any of claims 17, 19 and 20, wherein the first network entity is an access and mobility management function (AMF) .
The second terminal device of any of claims 18-20, wherein the second network entity is a location management function (LMF) .
A first network entity comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the first network entity at least to:

transmit, to a first terminal device, an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and

transmit, to a second terminal device, at least one identifier of at least one attribute set satisfied by the second terminal device.
The first network entity of claim 28, wherein the identifier list is transmitted to the first terminal device during a registration procedure of the first terminal device.
The first network entity of claim 28, wherein the first network entity is caused to transmit the identifier list by:

receiving, from a second network entity, a request message for the sidelink positioning procedure, wherein the request message comprises the identifier list and a routing identifier of the second network entity; and

transmitting, to the first terminal device, the request message.
The first network entity of claim 28, wherein the first network entity is caused to transmit the identifier list by:

receiving, from the first terminal device, a query message comprising an identifier of the first terminal device;

transmitting, to a second network entity, the query message;

receiving, from the second network entity, the identifier list and a routing identifier of the second network entity; and

transmitting, to the first terminal device, the identifier list and the routing identifier.
The first network entity of claim 31, wherein the first network entity is further caused to:

transmit, to the second network entity, a report of the first terminal device,

wherein the report comprises at least one of the following:

at least one role of the first terminal device during a discovery procedure;

capability information of the first terminal device;

status information of the first terminal device; or

environment information of the first terminal device.
The first network entity of claim 31 or 32, wherein the query message is one of the following:

an uplink (UL) non-access stratum (NAS) TRANSPORT message;

a mobile-originated location request (MO-LR) message; or

a supplementary service message.
The first network entity of any of claims 31-33, wherein the query message is based on a quality of service (QoS) for the sidelink positioning procedure.
The first terminal device of any of claims 31-34, wherein query message further comprises at least one of the following:

at least one role of the first terminal device during the discovery procedure;

capability information of the first terminal device to be synchronized;

status information of the first terminal device to be synchronized; or

environment information of the first terminal device to be synchronized.
The first network entity of any of claims 28-35, wherein the at least one identifier is transmitted to the second terminal device during a registration procedure of the second terminal device.
The first network entity of any of claims 28-35, wherein the first network entity is further caused to:

receive, from the second terminal device, a first match query message comprising the identifier list, an identifier of the second terminal device, and a routing identifier of a second network entity associated with the sidelink positioning procedure for the first terminal device;

transmit, to the second network entity, a second match query message comprising information associated with the first match query message and an identifier of the second terminal device; and

receive, from the second network entity, a match response message indicative of matching between the identifier list and the at least one identifier of at least one attribute set satisfied by the second terminal device.
The first network entity of claim 37, wherein the information associated with the first match query message comprises the identifier list, the second match query message further comprises a report of the second terminal device,

wherein the report comprises at least one of the following:

at least one role of the second terminal device during a discovery procedure;

capability information of the second terminal device;

status information of the second terminal device; or

environment information of the second terminal device.
The first network entity of claim 37, wherein the first network entity is further caused to:

determine a subset of identifiers from the identifier list based on at least one of the following:

at least one role of the second terminal device during a discovery procedure;

capability information of the second terminal device;

status information of the second terminal device; or

environment information of the second terminal device,

wherein the information associated with the first match query message comprises the subset of identifiers.
The first network entity of any of claims 37-39, wherein the first match query message further comprises at least one of the following:

at least one role of the second terminal device during a discovery procedure;

capability information of the second terminal device to be synchronized;

status information of the second terminal device to be synchronized; or

environment information of the second terminal device to be synchronized.
The first network entity of any of claims 37-40, wherein the first match query message is one of the following:

an uplink (UL) non-access stratum (NAS) TRANSPORT message;

a mobile-originated location request (MO-LR) message; or

a supplementary service message.
The first network entity of any of claims 28-41, wherein an attribute set among the attribute set list or the at least one attribute set comprises at least one of the following:

a type of a location request;

at least one role of a terminal device during the discovery procedure;

capability information of the terminal device;

status information of the terminal device; or

environment information of the terminal device.
The first network entity of any of claims 38-40 and 42, wherein the capability information comprises at least one of the following:

at least one location services (LCS) and ranging capability; or

at least one capability defined in at least one of a long term evolution (LTE) positioning protocol (LPP) or a ranging/sidelink positioning protocol (RSPP/SLPP) .
The first network entity of any of claims 38-40 and 42, wherein the environment information comprises at least one enhanced cell identified (ECID) measurement or at least one runtime QoS context for the sidelink positioning procedure.
The first network entity of any of claims 28-44, wherein the first network entity is further caused to:

receive, from a second network entity, a request for checking a capability of the second terminal device;

determine a subscription of the second terminal device;

determine capability information of the second terminal device based on a query to a unified data management function (UDM) or a policy control function (PCF) ; and

transmit, to the second network entity, the subscription and the capability information of the second terminal device.
The first network entity of any of claims 28-45, wherein the first network entity is an access and mobility management function (AMF) .
The first network entity of any of claims 30-35, 37-40 and 45, wherein the second network entity is a location management function (LMF) .
A second network entity comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the second network entity at least to:

receive, from a first network entity, a match query message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for a first terminal device and an identifier of the second terminal device; and

based on determining that the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device, transmit, to the first network entity, a message indicative of matching between the identifier list and the at least one identifier.
The second network entity of claim 48, wherein the match query message further comprises a report of the second terminal device, and the second network entity is further caused to:

determine the at least one identifier of the at least one attribute set satisfied by the second terminal device at least based on the match query message,

wherein the report comprises at least one of the following:

at least one role of the second terminal device during a discovery procedure;

capability information of the second terminal device;

status information of the second terminal device; or

environment information of the second terminal device.
The second network entity of claim 48, wherein the second network entity is further caused to:

determine the at least one identifier of the at least one attribute set satisfied by the second terminal device at least based on a query to a unified data management function (UDM) or a Policy Control Function (PCF) .
The second network entity of claim 48, wherein the second network entity is further caused to:

transmit, to the first terminal device, a request message for the sidelink positioning procedure, wherein the request message comprises the identifier list and a routing identifier of the second network entity.
The second network entity of claim 48, wherein the second network entity is further caused to:

receive, from the first network entity, a query message comprising an identifier of the first terminal device;

determine the identifier list; and

transmit the identifier list and a routing identifier of the second network entity to the first network entity.
The second network entity of claim 52, wherein the second network entity is further caused to:

receive, from the first network entity, a report of the first terminal device, wherein the identifier list is determined at least based on the report of the first terminal device,

wherein the report comprises at least one of the following:

at least one role of the first terminal device during a discovery procedure;

capability information of the first terminal device;

status information of the first terminal device; or

environment information of the first terminal device.
The second network entity of any of claims 48-53, wherein the identifier list is determined at least based on a query to a UDM/PCF.
The second network entity of any of claims 48-54, wherein the second network entity is further caused to:

receive, from the first terminal device, a message indicative of the matching; and

transmit, to the first terminal device, an indication of whether to select the second terminal device for the sidelink positioning procedure.
The second network entity of claim 55, wherein the second network entity is further caused to:

transmit, to the first network entity, a request for checking a capability of the second terminal device;

receive, from the first the second network entity, the subscription and the capability information of the second terminal device; and

determine whether to select the second terminal device for the sidelink positioning procedure.
The second network entity of any of claims 48-56, wherein an attribute set among the attribute set list or the at least one attribute set comprises at least one of the following:

a type of a location request;

at least one role of a terminal device during the discovery procedure;

capability information of the terminal device;

status information of the terminal device; or

environment information of the terminal device.
The second network entity of claim 57, wherein the capability information comprises at least one of the following:

at least one location services (LCS) and ranging capability; or

at least one capability defined in at least one of a long term evolution (LTE) positioning protocol (LPP) or a ranging/sidelink positioning protocol (RSPP/SLPP) .
The second network entity of any of claims 57-58, wherein the environment information comprises at least one enhanced cell identified (ECID) measurement or at least one runtime QoS context for the sidelink positioning procedure.
The second network entity of any of claims 48-59, wherein the first network entity is an access and mobility management function (AMF) , and the second network entity is a location management function (LMF) .
A method comprising:

obtaining, at a first terminal device, an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and

transmitting, during a discovery procedure for the sidelink positioning procedure, a broadcast message comprising the identifier list.
A method comprising:

receiving, at a second terminal device from a first terminal device, a broadcast message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and

determine whether the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device.
A method comprising:

transmitting, at a first network entity to a first terminal device, an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and

transmitting, to a second terminal device, at least one identifier of at least one attribute set satisfied by the second terminal device.
A method comprising:

receiving, at a second network entity from a first network entity, a match query message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for a first terminal device and an identifier of the second terminal device; and

based on determining that the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device, transmitting, to the first network entity, a message indicative of matching between the identifier list and the at least one identifier.
An apparatus comprising:

means for obtaining an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and

means for transmitting, during a discovery procedure for the sidelink positioning procedure, a broadcast message comprising the identifier list.
An apparatus comprising:

means for receiving, from a first terminal device, a broadcast message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and

means for determine whether the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device.
An apparatus comprising:

means for transmitting, to a first terminal device, an identifier list corresponding to an attribute set list for a sidelink positioning procedure for the first terminal device; and

means for transmitting, to a second terminal device, at least one identifier of at least one attribute set satisfied by the second terminal device.
An apparatus comprising:

means for receiving, from a first network entity, a match query message comprising an identifier list corresponding to an attribute set list for a sidelink positioning procedure for a first terminal device and an identifier of the second terminal device; and

means for based on determining that the identifier list matches at least one identifier of at least one attribute set satisfied by the second terminal device, transmitting, to the first network entity, a message indicative of matching between the identifier list and the at least one identifier.
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 claims 61-64.