Improvements in and relating to localisation in a telecommunication network

Abstract

A method of conducting localisation based on proximity Services (ProSe) for a set of User Equipment (UE) in a 5G network by initiating a 5G ProSe direct communication between UEs of the set and a reference UE to relay location information from a remote UE, which is included in the set of UEs, via the reference UE and a 5G core (5GC) entity (e.g. a location management function, LMF). Alternatively, the role of the reference UE may be fulfilled by a Positional Reference Unit (PRU). The method may further comprise the set of UEs registering ProSe capabilities with an application management function (AMF), for example to give an intention to select a UE from the set of UEs or from outside the set of UEs as the reference UE, if the UE is device-to-device (D2D) range. Three different purposes are disclosed: signalling overhead reduction, out-of-coverage localisation and under range extension. The common feature of the embodiments is the leveraging and enhancement of 5G Prose Direct Communication and 5G ProSe UE-to-Network Relay techniques to support location reporting. The disclosure allows ProSe to support the obtaining of location estimates or assistance data for a group of UEs.

Description

5 The present invention relates to localisation in a telecommunication network. Localisation, in this context, refers to the process of the network determining the location of one or more User Equipments, UEs, in the network. Localisation may also be known as positioning and both terms are used interchangeably in the art. 10 Embodiments of the present invention relate to the use of Proximity Services (ProSe) based D2D (Device to Device) localisation, which can be applied for localisation in different scenarios, from in-coverage group, or set, of UEs to range extension in connecting out-of-coverage UEs. A common feature of embodiments of the invention is the leveraging and enhancement of Fifth Generation (5G) ProSe Direct Communication and 5G ProSe UE-to-Network Relay techniques 15 to support location reporting. Embodiments of the invention provide enhanced messaging between different functions to orchestrate this ProSe based localisation. Further, additional embodiments, including the configuration of LPI (Localisation Privacy Indication) are disclosed. 3GPP SA2 completed the eLCS (enhanced Location Services) phase 2 work item in Release 20   17 and produced related updates to TS 23.273. Currently, discussions are ongoing regarding the content for Release 18 SA2 work, due to start in January 2022, and there is strong support for both localisation and ProSe topic continuation. D2D (Device to Device) based localisation will be prominent in SA2 Release 18, as there is also a strong interest in the RAN counterpart, the NR-sidelink based positioning. 25 A problem in the prior art is that there is currently no means provided to allow ProSe to support the obtaining of location estimates or assistance data for a group or set of UEs. This problem falls between the domains of Localisation, ProSe and Relaying. 30 It is an aim of embodiments of the present invention to address shortcomings in the prior-artand provide an improved localisation solution. According to the present invention there is provided an apparatus and method as set below. Other features of the invention will be apparent from the description which follows. 35 According to an aspect of the invention, a solution is provided whereby ProSe based D2D localisation can be conducted for a group of UEs or set of UEs for the purpose of one or more of: signalling overhead reduction; out-of-coverage localisation; and under range extension. Embodiments of the invention provide an architectural arrangement to initiate a 5G ProSe direct communication and a 5G ProSe UE-to-Network Relay to share location information between a remote UE and 5G core (5GC) (e.g. a Location Management Function, LMF). 5 Furthermore, a privacy issue may arise in these scenarios, as the UEs must pass their location information through a ProSe-enabled UE (as lead UE or a ProSe UE-to-Network Relay) which would want to know such a lead UE before giving privacy consent. Embodiments of the invention provide a solution to achieve this LPI and update the 5GC (e.g. the LMF) on this LPI. 10 Embodiments of the invention enhance 5G ProSe Direct Communication and 5G ProSe UE-to-Network Relay and associated capabilities for location reporting. In the following, reference is made to a Lead UE and / or a UE-to-Network Relay. The skilled person will understand that, depending on the context, the lead UE may act as a UE-to-Network Relay. 15 For the purposes of this invention, it is worth noting that the functionality of a 5G ProSe UE-to-Network Relay (or lead UE) is assumed to be carried out by a so-called Reference UE, so the terms 5G ProSe UE-to-Network Relay and Reference UE can be used indistinctly. In addition to the relaying capabilities proposed in this invention, a Reference UE is understood to determine 20 a reference plane and reference direction when performing ranging or sidelink positioning between two or more UEs, as defined in 3GPP TR 23.700-86 [1], In addition, a UE acting as Reference UE to other UEs may also act as Positioning Reference Unit (PRU) to the network, whereby a PRU is defined as a UE with known location to the network that may assist with the enhancement of the positioning performance of other UE(s), as defined in 3GPP TS 38.305 [2], 25 According to an aspect of the present invention, there is provided a system of localisation whereby a Location Management Function, LMF, in the network is arranged to access certain other functions in the network to orchestrate this localisation, both in in-coverage and out-of-coverage scenarios. 30 In an embodiment, out-of-coverage localisation and / or under-range extension are achieved by means of configuring the LMF to orchestrate the localisation activity and to have contact with such other network functions as are required. In a preferred embodiment, this contact is direct contact. Details of this contact and the means by which this can be achieved are shown in the 35 accompanying figures. A first aspect provides a method of conducting localisation based on Proximity Services, ProSe, (e.g. ProSe based D2D localisation) for a set of User Equipments, UEs, in a 5G network comprising the set of UEs, an Access and Mobility Management Function, AMF, a Location Management Function, LMF, and a ProSe Application Server, AS, for example for a purpose of signalling overhead reduction and / or range extension, by initiating a 5G ProSe direct communication, for example between UEs of the set of UEs and a reference UE, for example included in the set of UEs, to share and / or relay location information between and / or from a 5 remote UE, included in the set of UEs, for example via the reference UE and / or a 5G core, 5GC, (e.g. a 5GC entity) for example the LMF; wherein the method comprises: authorizing and configuring, by the ProSe application server or the PCF, a UE of the set of UEs as the reference UE, through which the other UEs of the set of UEs relay location information to 10 the 5GC and the LMF; requesting, by the LMF, location data from multiple UEs of the set thereof, via the reference UE; and initiating, by the reference UE, side-link based positioning for the multiple UEs of the set thereof, including: obtaining, by the reference UE through the side-link, position estimates from the set 15 of UEs; obtaining, by the reference UE through the side-link, which UE of the set of UEs would carry out UE based positioning; obtaining, by the reference UE through the side-link, positioning assistance data from the set of UEs; and / or executing, by the reference UE through the sidelink, a side-link based positioning method and gaining position information of the group of UEs. 20 In one example, the method comprises registering, by the set of UEs, ProSe capabilities thereof the AMF, for example with an intention to select a UE from the set of UEs or from outside the set of UEs if the UE is in D2D range, as a reference UE. In one example, the role of the reference UE is fulfilled by a PRU (Positional Reference Unit), as defined in 3GPP Release 18. 25 In one example, registering, by the set of UEs, the ProSe capabilities thereof with the AMF comprises giving, by the set of UEs to the AMF, Location Privacy Indicators, LPIs, for localisation based on ProSe thereof. In one example, the method comprises starting, by the LMF, localisation procedures. In one example, the method comprises identifying, by the LMF, the set of UEs with certain group or collective behaviour. In one example, the method identifying, by the LMF, the set of UEs with certain group or 35 collective behaviour is based on internal logic within the LMF or input data from other Network Functions, NFs. In one example, identifying, by the LMF, the set of UEswith certain group or collective behaviour comprises considering, by the LMF, all UEs within an area of interest for ProSe based localisation, leaving any grouping or pairing to direct discovery protocol of the ProSe. 5 In one example, the method comprises checking, by the LMF, the ProSe capabilities of the set of UEs registered with the AMF. In one example, the method comprises requesting or subscribing, by the LMF, a newly defined service of the ProSe AS to initiate relay for location reporting for the set of UEs; or interacting, 10 by the LMF with a Policy Control Function, PCF, to initiate relay for location reporting for the set of UEs. In one example, the reference UE is outside the set of UEs but still within D2D range or, the reference UE role is fulfilled by a PRU (Positional Reference Unit). 15 In one example, the method comprises configuring or provisioning the reference UE with special Relay Service Codes, RSCs, authorized for location reporting, optionally wherein the special RSCs are provided by the PCF or already provisioned in the Mobile Equipment, ME, or the reference UE, or configured in the universal integrated circuit card, UICC. 20 In one example, the method comprises authorizing, configuring or provisioning, by the ProSe application server or the PCF, the other UEs of the set thereof with special RSCs authorized for location reporting, optionally wherein the special RSCs are provided by the PCF or already provisioned in the ME or configured in the UICC. 25 In one example, the method comprises conducting ProSe Relay Discovery on the identified set of UEs with special RSCs based on either Discovery Model A or Discovery Model B, wherein the Discovery Model A and the Discovery Model B are defined in TS 23.303 and TS 23.304, respectively. 30 In one example, the method comprises establishing connections over PC5 between the reference UE and the other UEs of the set thereof, for the discovered set of UEs. In one example, the method comprises responding or notifying, by the ProSe AS or the PCF to 35 the LMF, when the relay configuration is complete. In one example, the method comprises relaying, by the reference UE, location reporting data back to the LMF. In one example, the method is carried out with the support of a PRU (Positional Reference Unit) instead of a reference UE. In one example, the signalling overhead reduction is by means of positioning protocol messages 5 and / or range extension by gaining location information of UEs outside the network coverage area. In one example, the location information is passed onto a Location Service, LCS, client, through the AMF and a Gateway Mobile Location Centre, GMLC. 10 A second aspect provides a 5G network comprising a set of UEs, an Access and Mobility Management Function, AMF, a Location Management Function, LMF, and a ProSe Application Server, AS, configured to implement the method according to the first aspect. 15   Although a few preferred embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims. For a better understanding of the invention, and to show how embodiments of the same may be 20 carried into effect, reference will now be made, by way of example only, to the accompanying diagrammatic drawings in which: Figure 1 shows a representation of a first scenario according to an embodiment of the invention; 25 Figure 2 shows a representation of a second scenario according to an embodiment of the invention; Figure 3 shows a message flow associated with the first scenario; and 30 Figure 4 shows a message flow associated with the second scenario. A first embodiment of the present invention relates to a first Scenario concerned with reducing an overhead associated with location signalling. 35 Many high-volume localisation applications (such as stadium / theme park / train platform entry and shopping mall visitor tracking) show intrinsic group or collective behaviour patterns among the users. These joint patterns can be identified and effectively used in D2D based localisation to reduce the signalling overheads significantly. Architectural support for D2D based localisation has not yet discussed in standardisation meetings, and is likely to be a key topic for a future release. In this scenario, all the UEs would be ‘in coverage’, i.e. the 5GC (e.g. an LMF) would be able to communicate with the individual UEs directly. The LMF would preferably identify possible UEs to perform localisation in D2D mode. This also 5 requires interaction with 5GC (e.g. AMF, the ProSe application server, PCF or UDM), as will be outlined below, to check the ProSe capabilities of the UEs and to check the updated LPI status of each UE to share location information through another UE (e.g. a lead or a ProSe UE-to-Network Relay). Even with a sub-set of the initially identified UEs, significant savings in positioning protocol message overheads (e.g. LPP) between the UE and the network can be 10 achieved as shown in [3], A depiction of a location signalling reduction in this scenario 1 is shown in Figure 1, which shows a stadium 1 having a 5G-NR access point 10 having an associated coverage area 11. Within the coverage area are a plurality of individual users. Some of these users may be considered as 15 one or more identified user groups 20, as set out above. A second embodiment relates to localisation through non-public network range extension. In this scenario, D2D links are used to extend the range of a network, in particular a Private or 20 Non-Public Network (NPN). In this example, the network whose range is extended is an Industry loT (lloT) network, where the NPN spans the area of the industry site and is operable to locate all the people and connected devices (lorries, forklifts etc) within the site for reasons such as process efficiency orsafety / security. 25 Figure 2 shows a representation of this scenario. A factory or similar environment has an lloT network which has a coverage area depicted by 100. Outside this area, there is a PLMN 120. There may be related people or devices just outside the site (and beyond the NPN full coverage area), where the NPN network will have a legitimate reason or benefit in localizing such devices. 30 As an example, these devices may be lorries 110 carrying supplies to the site, which are waiting in a queue to get clearance to enter. As the NPN Access Points (APs) will have weaker coverage as the queue extends beyond the range of the NPN, the NPN has to rely on the Public network (PLMN) if this is available at the site. However, extra payments will have to be made to the PLMN to get this service and delays in the service can also occur, both of which are undesirable. 35 An alternative and a cost / time efficient solution is to utilize the D2D (i.e. ProSe) connection capability between the devices (or UEs) of the lorries in this scenario. Such D2D links are shown by the arrows between the lorries 110. The First lorry in the queue (i.e. the one nearset the factory) will have reasonable coverage from the NPN and can be localized through the NPN Access Points (APs). The first lorry (or device) can request the use of D2D capability from subsequent lorries in the queue - for them to be localized through D2D. Furthermore, for this localisation process, relaying messages through the lead UE (i.e. the first lorry) can be configured. 5 This example shows a form of range extension of the NPN, achieved through the first device in the queue, which has good connections to the NPN. The range of the NPN is effectively extended by means of the D2D links between the first and subsequent lorries. In this way, a remote lorry which would be unreachable for being beyond the range of the NPN, can still be 10 localised by the NPN via use of the D2D link(s) between the remote lorry and the NPN, possibly via one or more intermediate lorries. Returning to the first embodiment, Figure 3 shows a message flow diagram associated with this embodiment. 15 One of the main benefits of identifying intrinsic groups 20 within the plurality of users shown in Figure 1 and using ProSe within the group or set of UEs to relay location information back to the 5GC (e.g. LMF) in this scenario is the overhead reduction in positioning protocol messages. It is assumed that there is a periodic localisation request from a Location Services (LCS) client and 20 the initial localisation steps are already conducted, and the LMF has started individual tracking of the UEs. In some applications (e.g. in private networks), the UEs will readily share the location information with any other member UEs, so it can be assumed that the LPI is already granted for ProSe scenarios before the start of the localisation process. The associated call flow is shown in Figure 3 and details of the individual steps follow. 25 At step 0, the ProSe capabilities of the UEs 200, 201 will be registered with the AMF 210 beforehand. A new Information Element (IE) may be registered as part of this step indicating the support for location reporting in addition to other ProSe capabilities. Also, the LPI for ProSe based localisation may be given by the UE’s at this stage, again to the AMF 210. 30 When the localisation request comes from the LCS 260 client for a high-volume application, the LMF 220 will start the localisation procedures as in a default scenario for periodic location requests, as given by TS23.273, section 6.3.1. 35 At step 1, the LMF 220 may identify a set of UEs 200, 201 with certain group or collective behaviour and thus can take steps to initiate the ProSe based localisation for these UEs. This can be based on internal logic within LMF or input data from other Network Functions (NFs). Alternatively, the LMF 220 may consider all UEs within an area of interest for ProSe based localisation, leaving any grouping or pairing to the direct discovery protocol of the ProSe. At Step 2, the LMF 220 will check the ProSe capabilities registered for the UEs (in Step 0), with the AMF210. 5 At Step 3, for the UEs supporting ProSe capability (including also location reporting), the LMF 210, will request or subscribe to a newly defined service of the ProSe application server 230 to initiate Relay for location reporting. As an alternative, the LMF 210 may interact with Policy Control Function (PCF) 230 instead of ProSe application server 230 for step 3. 10 At Step 4, the ProSe application server (or the PCF) 230 will authorize and configure a UE as lead UE 201 or a ProSe UE-to-Network Relay through which the other UEs 200 can relay location information to the 5GC and LMF 220. The lead UE 201 is configured or provisioned with special Relay Service Codes (RSCs) authorized for location reporting. This is provided by the PCF 230 or already provisioned in the ME (Mobile Equipment) or UE, or configured in the 15 universal integrated circuit card (UICC). At step 5, the ProSe application server (or the PCF) 230 will authorize, configure or provision other UEs with special RSCs authorized for location reporting. This is provided by the PCF 230 or already provisioned in the ME or configured in the UICC. 20 At Step 6, the ProSe Relay Discovery on the UEs identified in Steps 1-3, is conducted with special RSCs based on either model A or Model B. The Discovery Model A and Discovery Model B are known in the prior art as defined in TS 23.303 and TS 23.304. 25 At step 7, once discovered, the connections between the lead UE 201 or a ProSe UE-to-Network Relay and the other UEs 200 are established over PC5. At step 8, the ProSe application server (or PCF) 230 will respond or notify to the LMF 220, when the relay configuration is complete (e.g. based on a notification received by AMF 210 or SMF 30 (not shown) from the ProSe UE-to-Network Relay after completion). It is not necessary to establish any UP (User Plane) PDU (Protocol Data Unit) session for such special RSCs between the ProSe UE-to-Network Relay and network as such RSCs may not be associated with any specific PDU session parameters. 35 At step 9, the LMF 220 will request location data from multiple UEs 200, via the lead UE 201 or ProSe UE-to-Network Relay. At step 10, the lead UE 201 or ProSe UE-to-Network Relay will initiate side-link based positioning for the multiple UEs 200 (as instructed by the LMF 220 in step 9). This may include obtaining position estimates from the group of UEs 200, who would carry out UE based positioning, obtaining positioning assistance data from these UEs or even executing a side-link based positioning method (and gaining position information of the group of UEs). Whatever the method used, the lead UE 201 or ProSe UE-to-Network Relay will collect this data through the side-link 5 in step 10. At step 11, the UEs 200 will provide this data over PC5 communication session to the lead UE 201 as established in step 7-8. 10 At step 12, the lead UE 201 or ProSe UE-to-Network Relay will relay location reporting data back to the LMF 220. This can be over NAS MM messages via the AMF 210 or NAS SM messages via SMF (not shown). The signalling overhead reduction comes by means of positioning protocol messages (e.g. LPP) from the lead UE 201 or ProSe UE-to-Network Relay to the LMF 220. If the location information from multiple UEs is concatenated into fewer protocol 15 messages at the lead UE 201 or at the ProSe UE-to-Network Relay, then there are significant signalling overhead savings, when compared to prior art techniques where such a direct link between the lead UE 201 and the LMF 22 is not possible. In steps 13-15, the location information is passed onto the LCS client 260, through the AMF 210 20 and the Gateway Mobile Location Centre (GMLC) 240. These steps are not changed from the default location responses in the prior art in section 6.3.1 of TS23.273. The configuration (or provisioning) of the lead UE 201 or other UEs in step 4 or step 5 can be considered as part of ProSe Policy, as one component in UE Route Selection Policy (URSP) or 25 as part of any other side link / ranging policies to be configured (or provisioned) to the Sidelink Positioning-enabled UEs for this purpose. Special RSCs in steps 4 to 6 (or step 8) can be replaced by any other ProSe identifiers or side link identifiers exchanged as part of discovery operations for Sidelink Positioning and Ranging 30 in order to authorize location reporting. As will be appreciated, the direct messaging between the lead UE 201 and the LMF 220 reduces the signalling overhead significantly. 35 In the previous description, relating to Figure 3, it was assumed that the LPI is provided to the AMF 210 before the ProSe based localisation process begins. However, in some situations, the UEs 200, 201 would want to provide or update their LPI (e.g. on the fly or in real time). This is especially true in cases where the networks are more open to subscribers and where the set of UEs, groups and lead UEs are chosen from a wide variety of UEs. In another embodiment of this invention, the AMF 210 advises the LMF 220 and / or GMLC 240 of the need for LPI, in step 2. The LMF 220 and / or GMLC 240 will then indicate the need for LPI to the ProSe application server (or PCF) 230, in the message in step 3. The ProSe application 5 server (or PCF) 230, in steps 4 and 5, will indicate to the UEs (lead UE 201 or ProSe UE-to-Network Relay and other UEs 200) to provide the new LPI to the AMF 210. The UEs (this can be a subset of UEs if all of the UEs do not agree on using ProSe for localisation in this context) will provide the LPI in NAS messaging to the AMF 210 at this stage, and the AMF 210 will record these LPIs in the User Data Repository (UDR), to be accessed via the Unified Data Management 10 function (UDM) 250. These steps are additional steps, positioned between steps 5 and 6 in the message flow shown in Figure 3. The LMF 220 and / or GMLC 240 then checks the LPI status with the UDM 250 in a new step, preceding step 9. 15 Once the LMF 220 and / or the GMLC 240 receives the LPI indications from the UDM 250, the LMF 220 (or LMF 220 on notification from GMLC 240) only selects the UEs who have given a positive LPI. The LMF 220 requests the location information for these UEs from the lead UE 201 or ProSe UE-to-Network Relay in step 9. The remaining steps will follow, as in Figure 3, for this 20 subset of UEs. Referring again to Figure 2 and the scenario depicted therein, this embodiment relates to a situation where out-of-coverage UEs can Relay their location through an in-coverage UE, for commercial applications. A Private NPN is assumed in this illustration, where all UEs (and 25 devices) within and coming into the NPN have given their privacy consent to be localized by the NPN. This range extension situation occurs when some of the UEs 110 are just outside the NPN 100, waiting for entry into the industry premises. However, these UEs or devices would not have given their privacy consent to be localized through another ‘lead’ UE or ProSe UE-to-Network Relay. In this case, explicit LPI is needed to proceed with the ProSe based localisation and then 30 Relaying. This issue is addressed in the following. Figure 4 shows a call flow according to this embodiment of the invention. The entities here share reference numerals with similar entities in Figure 3, but it will be appreciated that each may perform different functions depending upon the exact embodiment. The steps are labelled 0 to 35    18, but this numbering is distinct from that shown in Figure 3, At step 0, the call flow starts registration including new 5G ProSe capabilities. With a multiple UE localisation request by the LCS client 260. The LMF 220 carries out these localisations as per the default MT-LR procedure detailed in section 6.1.2 in TS 23.273, known in the prior art. At Step 1, the LMF 220 notices that some of the UEs 200 or devices needing localisation are not within the NPN 100. 5 At Step 2, the LMF 220 makes ProSe capability checks for these devices (from Step 1) with the AMF 210. These ProSe capabilities would have been registered with the AMF previously, or even the wider PLMN can be used by the AMF to carry out these capability checks, as part contained in TS 23.700-07, ‘Study on enhanced support of Non-Public Networks (NPN)’. 10 At Step 3, for the UEs that show ProSe capability, the LMF 220 requests the ProSe Application Server (or PCF) 230 to initiate ProSe configuration, through UE(s) at the cell edge of the NPN. At Steps 4 and 5, the ProSe authorization, configuration and provisioning is carried out by the ProSe Application Server (or the PCF) 230. The lead UE 201 configuration at the cell edge can 15 be done through the NPN, but for the other ‘remote’ UEs, the configuration is done based on parameters already provisioned in the ME or UE or configured in the UICC. At steps 6 and 7 the relay discovery for the special RSC’s used and the establishment of a PC5 communication session are executed. These steps are similar to steps 6 and 7 of Fig. 3 and so 20 are not described again. CXI At Step 8, the ProSe AS or the PCF 230 respond back to the LMF 220, indicating the establishment of the Relay links. This step is similar to step 8 of Fig. 3. 25 At Step 9, the UEs provide LPI through NAS messaging to the AMF 210. This step is optional, as in some cases, the UE configuration itself can carry this consent for localisation in the relay mode. Physically, these messages are relayed through by the lead UE 201. The LPI are then recorded in the UDR and managed by UDM 250, as shown in step 10. 30 For step 11, there are two possible variants. In the first variant (step 11a), the LMF 220 accesses the AMF 210 to acquire an update of the LPI information. The AMF 210 exchanges messages with the UDM 250 and then the AMF 210 can report back to the LMF 220. In the second variant (step 11b), the LMF 220 (either itself or in coordination with the GMLC 240) directly accesses the UDM 250 for LPI information for these multiple UEs. Step 11b is the quicker option but 35 requires some changes to the capabilities of LMF 220 to enable this direct access. At Step 12, for the UEs who provide positive LPI, the LMF 220 will request the lead UE 201 to provide the location information Steps 13-8 are similar to steps 10-15 shown in Fig. 3, so further description is omitted for brevity. The configuration (or provisioning) of the lead UE 201 or other UEs in step 4 or step 5 can be considered as part of ProSe Policy, as one component in UE Route Selection Policy (URSP) or 5 as part of any other side link / ranging policies to be configured (or provisioned) to the Sidelink Positioning -enabled UEs for this purpose. Special RSCs in steps 4 to 7 can be replaced by any other ProSe identifiers or side link identifiers exchanged as part of discovery operations for Sidelink Positioning and Ranging in order to 10 authorize location reporting. At least some of the example embodiments described herein may be constructed, partially or wholly, using dedicated special-purpose hardware. Terms such as ‘component’, ‘module’ or ‘unit’ used herein may include, but are not limited to, a hardware device, such as circuitry in the form 15 of discrete or integrated components, a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks or provides the associated functionality. In some embodiments, the described elements may be configured to reside on a tangible, persistent, addressable storage medium and may be configured to execute on one or more processors. These functional elements may in some embodiments include, by way of 20 example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Although the example embodiments have been described with reference to the components, modules and units discussed herein, 25 such functional elements may be combined into fewer elements or separated into additional elements. Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. 30 Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of others. [1 ] 3GPP TR 23.700-86: Study on Architecture Enhancement to support Ranging based 35 services and sidelink positioning [2] 3GPP TS 38.305: NG Radio Access Network (NG-RAN); Stage 2 functional specification of User Equipment (UE) positioning in NG-RAN CXI CXI [3] M. Hunukumbure, O. Kolawole, D. M. Gutierrez-Estevez, “Optimising UWB based Location Tracking in Smartphones through the Support of 5G”, IEEE ICCE conference, Las Vegas, Jan. 2022.

Claims

1. A method of conducting localisation based on Proximity Services, ProSe, for a set of User Equipments, UEs, in a 5G network comprising the set of UEs, an Access and Mobility5 Management Function, AMF, a Location Management Function, LMF, and a ProSe Application Server, AS, by initiating a 5G ProSe direct communication between UEs of the set of UEs and a reference UE, to relay location information from a remote UE, included in the set of UEs, via the reference UE and the LMF;wherein the method comprises:10 authorizing and configuring, by the ProSe application server or the PCF, a UE of the set of UEs as the reference UE, through which the other UEs of the set of UEs relay location information to the 5GC and the LMF;requesting, by the LMF, location data from multiple UEs of the set thereof, via the reference UE; and15 initiating, by the reference UE, side-link based positioning for the multiple UEs of the set thereof, including: obtaining, by the reference UE through the side-link, position estimates from the set of UEs; obtaining, by the reference UE through the side-link, which UE of the set of UEs would carry out UE based positioning; obtaining, by the reference UE through the side-link, positioning assistance data from the set of UEs; and / or executing, by the reference UE through the side-20 link, a side-link based positioning method and gaining position information of the group of UEs.

2. The method according to claim 1, comprising registering, by the set of UEs, ProSe capabilities thereof with the AMF, with an intention to select a UE from the set of UEs or from outside the set of UEs if the UE is in D2D range, as the reference UE.

253. The method according to claim 2, wherein registering, by the set of UEs, the ProSe capabilities thereof with the AMF comprises giving, by the set of UEs to the AMF, Location Privacy Indicators, LPIs, for localisation based on ProSe thereof.30   4. The method according to any of claims 2 to 3, comprising, starting, by the LMF, localisationprocedures.

5. The method according to any previous claim, comprising identifying, by the LMF, the set of UEs with certain group or collective behaviour.

6. The method according to claim 5, wherein identifying, by the LMF, the set of UEs with certain group or collective behaviour is based on internal logic within the LMF or input data from other Network Functions, NFs.

7. The method according to claim 5, wherein identifying, by the LMF, the set of UEs with certain group or collective behaviour comprises considering, by the LMF, all UEs within an area of interest for ProSe based localisation, leaving any grouping or pairing to direct discovery protocol of the ProSe.

58. The method according to any of claims 2 to 7, comprising checking, by the LMF, the ProSe capabilities of the set of UEs registered with the AMF.

9. The method according to any previous claim, comprising requesting or subscribing, by the 10 LMF, a newly defined service of the ProSe AS to initiate relay for location reporting for the set of UEs; or interacting, by the LMF with a Policy Control Function, PCF, to initiate relay for location reporting for the set of UEs.15   10. The method according to any previous claim, comprising configuring or provisioning thereference UE with special Relay Service Codes, RSCs, authorized for location reporting.

11. The method according to any previous claim, comprising authorizing, configuring or provisioning, by the ProSe application server or the PCF, the other UEs of the set thereof with20 special RSCs authorized for location reporting.

12. The method according to any of claims 4 to 11, comprising conducting ProSe Relay Discovery on the identified set of UEs with special RSCs based on either Discovery Model A or Discovery Model B, wherein the Discovery Model A and the Discovery Model B are defined in25 TS 23.303 and TS 23.304, respectively.

13. The method according to claim 12, comprising establishing connections over PC5 between the reference UE and the other UEs of the set thereof, for the discovered set of UEs.30   14. The method according to any previous claim comprising responding or notifying, by theProSe AS or the PCF to the LMF, when the relay configuration is complete.

15. The method according to any previous claim, comprising relaying, by the reference UE, location reporting data back to the LMF.

16. The method according to any previous claim, wherein the signalling overhead reduction is by means of positioning protocol messages and / or range extension by gaining location information of UEs outside the network coverage area.CXI17. The method according to any previous claim, wherein the location information is passed onto a Location Service, LCS, client, through the AMF and a Gateway Mobile Location Centre, GMLC.

18. A 5G network comprising a set of UEs, an Access and Mobility Management Function, AMF, 5 a Location Management Function, LMF, and a ProSe Application Server, AS, configured to implement the method according to any previous claim.

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