WO2024170154A1

WO2024170154A1 - Method, apparatus and computer program

Info

Publication number: WO2024170154A1
Application number: PCT/EP2024/050116
Authority: WO
Inventors: Taylan SAHIN; Prajwal KESHAVAMURTHY
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2023-02-17
Filing date: 2024-01-04
Publication date: 2024-08-22
Anticipated expiration: 2025-08-17
Also published as: GB202302310D0; GB2627284A; CN120476562A

Abstract

There is provided an apparatus comprising: means for obtaining congestion information related to a sidelink positioning; and means for determining, based on the obtained congestion information, sidelink positioning reference signal configuration information to be used for the sidelink positioning.

Description

METHOD, APPARATUS AND COMPUTER PROGRAM

FIELD

[0001] The present application relates to an apparatus, method and computer program. In particular, but not exclusively, the present application relates to congestion in a communication system.

BACKGROUND

[0002] A communication system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, base stations and/or other nodes by providing carriers between the various entities involved in the communications path. A communication system can be provided for example by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, video, electronic mail (email), text message, multimedia and/or content data and so on. Nonlimiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.

[0003] The communication system and associated devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and/or parameters which shall be used for the connection are also typically defined. One example of a communications system is UTRAN (3G radio). Other examples of communication systems are the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology and so-called 5G or New Radio (NR) networks. NR is being standardized by the 3rd Generation Partnership Project (3GPP). The Internet of Things (loT) comprises a network of physical devices which can communicate over the Internet. The “Internet of Everything” has been referred to as a networked connection of people, process, data, and things.

SUMMARY

[0004] According to a first aspect there is disclosed an apparatus comprising: means for obtaining congestion information related to a sidelink positioning; and means for determining, based on the obtained congestion information, sidelink positioning reference signal configuration information to be used for the sidelink positioning.

[0005] According to an example, the apparatus comprises means for comprising means for obtaining location information of one or more user devices for determining the sidelink positioning reference signal configuration information.

[0006] According to an example, the congestion information comprises one or more of: channel busy ratio; channel occupancy ratio. [0007] According to an example, the congestion information indicates that a first user device of the one or more user devices is experiencing a relatively high level of congestion and a second user device of the one or more user devices is experiencing a relatively low level of congestion.

[0008] According to an example, the sidelink positioning reference signal configuration information is configured for reducing the usage of radio resources at the first user device.

[0009] According to an example, the sidelink positioning reference signal configuration information is configured for increasing the usage of resources at the second user device.

[0010] According to an example, the second user device comprises a stand-by user device to the sidelink positioning, and the apparatus comprises means for causing the second user device to become active in the sidelink positioning.

[0011] According to an example, the sidelink positioning reference signal configuration information for one or more user devices comprises at least one transmission parameter, the at least one transmission parameter comprising at least one of: bandwidth; transmission frequency; transmission power.

[0012] According to an example, the apparatus comprises means for storing a mapping table for use when performing the determining sidelink positioning reference signal configuration information.

[0013] According to an example, the mapping table provides a mapping of a congestion level at the apparatus to a percentage of one or more user devices experiencing a congestion level below a threshold, and a mapping to sidelink positioning reference signal configuration information to be selected.

[0014] According to an example, the apparatus comprises a coordinating apparatus that comprises means for determining sidelink positioning reference signal configuration information for a plurality of respective user devices to use when transmitting positioning reference signals in the sidelink positioning.

[0015] According to an example, the apparatus comprises one of: a target user equipment to be positioned; a base station; a location management function.

[0016] According to an example, the apparatus comprises an anchor user device in the sidelink positioning.

[0017] According to an example, the anchor user device comprises means for determining sidelink positioning reference signal configuration information for the anchor user device itself to use when transmitting positioning reference signals in the sidelink positioning.

[0018] According to an example, the apparatus comprises means for receiving the congestion information. [0019] According to some examples, the means for receiving the congestion information is configured to receive the congestion information from one or more of: the one or more user equipment; a base station; a location management function.

[0020] According to a second aspect, there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: obtain congestion information related to a sidelink positioning; and determine, based on the obtained congestion information, sidelink positioning reference signal configuration information to be used for the sidelink positioning.

[0021] According to a third aspect, there is provided an apparatus comprising circuitry for obtaining congestion information related to a sidelink positioning; and determining, based on the obtained congestion information, sidelink positioning reference signal configuration information to be used for the sidelink positioning.

[0022] According to a fourth aspect, there is provided a method, comprising: obtaining congestion information related to a sidelink positioning; and determining, based on the obtained congestion information, sidelink positioning reference signal configuration information to be used for the sidelink positioning.

[0023] According to an example, the method comprises obtaining location information of one or more user devices for determining the sidelink positioning reference signal configuration information.

[0024] According to an example, the congestion information comprises one or more of: channel busy ratio; channel occupancy ratio.

[0025] According to an example, the congestion information indicates that a first user device of the one or more user devices is experiencing a relatively high level of congestion and a second user device of the one or more user devices is experiencing a relatively low level of congestion.

[0026] According to an example, the sidelink positioning reference signal configuration information is configured for reducing the usage of radio resources at the first user device.

[0027] According to an example, the sidelink positioning reference signal configuration information is configured for increasing the usage of resources at the second user device.

[0028] According to an example, the method comprises determining, by the apparatus comprising a coordinating apparatus, sidelink positioning reference signal configuration information for a plurality of respective user devices to use when transmitting positioning reference signals in the sidelink positioning.

[0029] According to an example, the method comprises determining, by an apparatus in an anchor user device, sidelink positioning reference signal configuration information for the anchor user device itself to use when transmitting positioning reference signals in the sidelink positioning. [0030] According to a fifth aspect there is provided a non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: obtaining congestion information related to a sidelink positioning; and determining, based on the obtained congestion information, sidelink positioning reference signal configuration information to be used for the sidelink positioning.

[0031] According to a sixth aspect there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least the following: obtaining congestion information related to a sidelink positioning; and determining, based on the obtained congestion information, sidelink positioning reference signal configuration information to be used for the sidelink positioning.

[0032] According to a seventh aspect there is provided a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: obtaining congestion information related to a sidelink positioning; and determining, based on the obtained congestion information, sidelink positioning reference signal configuration information to be used for the sidelink positioning.

[0033] According to an eighth aspect there is provided a computer program comprising instructions stored thereon for performing at least the following: obtaining congestion information related to a sidelink positioning; and determining, based on the obtained congestion information, sidelink positioning reference signal configuration information to be used for the sidelink positioning.

DESCRIPTION OF FIGURES

[0034] Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which:

[0035] Figure 1 schematically shows parts of a communication system according to an example;

[0036] Figure 2 is a signalling diagram according to an example;

[0037] Figure 3 is a signalling diagram according to an example;

[0038] Figure 4 is a signalling diagram according to an example;

[0039] Figure 5 is a signalling diagram according to an example;

[0040] Figure 6 shows a representation of a wireless communication device according to an example;

[0041] Figure 7 shows a representation of a control apparatus according to an example;

[0042] Figure 8 is a flow chart of a method according to an example;

[0043] Figure 9 is a schematic representation of non-volatile memory media.

DETAILED DESCRIPTION

[0044] The present disclosure relates to sidelink (SL) positioning. A “sidelink” connection enables direct communication between two devices, without the participation of a base station in the transmission and reception of data traffic between the two devices. For example, SL communication may occur between two user equipment (UE). In SL positioning, UEs transmit and/or receive SL positioning reference signals (SL PRS) to each other via an SL interface. On these transmitted/received signals, the UEs may perform one or more of time-, angle-, or power-based measurements. Using these measurements, the UEs can then calculate a position estimate. The position estimation could be in terms of absolute or relative location, or a range (for example relative distance and/or angle).

[0045] It is currently under discussion in 3GPP whether SL PRS can be transmitted in dedicated SL resource pools, or using resource pools shared with other SL traffic.

[0046] SL is expected to support high density of users with high amount of traffic (e.g., large number of vehicles in an urban intersection transmitting cooperation awareness messages every 100 ms). To avoid quality of service (QoS) degradation under high channel utilization, congestion control mechanisms have been introduced for SL communications, particularly for autonomous SL resource allocation, such as “mode 2” in 5G NR or RA “mode 4” in LTE.

[0047] Rel. 16 does not specify a particular congestion control algorithm, but defines related metrics and possible countermeasures to reduce the channel congestion. These metrics include Channel Busy Ratio (CBR) and the Channel occupancy Ratio (CR):

• CBR is defined as the ratio of occupied resources (determined by high received signal energy (S-RSSI)) in the most recent 100 subframes. CBR is a measurement of recent congestion present in the resource pool.

• CR estimates the channel occupancy generated by a transmitter UE. CR counts the total number of subchannels a UE has and will transmit in during a window of up to 1000 ms including the current subframe. CR is thus a measurement of how much resource a UE has recently, and will soon, claim.

[0048] Each SL packet is associated with a single priority value which is based on the QoS requirements of the message, passed down to the physical layer from upper layers. The priority value is transmitted in the first-stage sidelink control information (SCI) associated with each transport block.

[0049] A UE can be (pre-)configured with a set of CBR ranges to each of which is linked a CR-limit. When a UE finds its CR exceeds the CR-limit for the CBR range it currently measures, it should reduce its CR to not exceed the limit. How this is done is up to UE implementation.

[0050] A UE can modify the following transmission parameters per resource pool to reduce channel load:

1 . Number of sub-channels: the UE can reduce its CR by limiting the number of subchannels it can utilize. If a UE needs to fit a transport block (TB) to a reduced number of sub-channels, it can utilize, e.g., a higher order modulation and coding scheme (MCS).

2. Number of (re-)transmissions: the UE can reduce its CR by limiting the number of (re-)transmissions.

3. Transmission power: the UE can decrease the CBR by reducing its transmission power. If the CBR decreases to values within lower CBR ranges, the UE can utilize a higher CR limit

[0051] Packet priority and CBR can each also be (pre-)configured with mappings to ranges of values of transmission parameters, e.g., a range of MCS values, and/or a range of numbers of subchannels, etc. In this case, the UE chooses its transmission parameters from within the range corresponding to the prevailing PPPP (ProSe Per-Packet Priority) and/or CBR.

[0052] A potential problem, identified in the present disclosure, is that SL positioning may suffer from SL congestion. For example, SL congestion may be caused by a high density of users generating frequent message traffic, which is typical in, for example, vehicle-to- everything (V2X) use cases.

[0053] When legacy congestion control mechanisms are applied, SL PRS can be subject to a reduced number of subchannels. This may lead to reduced bandwidth, less frequent transmissions, or reduced transmit power. This may all lead to degradation of the positioning QoS, for example in terms of accuracy and latency.

[0054] Considering that a positioning service may be life-critical to many use cases (e.g., V2X, public safety), the present disclosure identifies that enhancements to the congestion control mechanisms may be needed, so that the positioning service does not suffer from degraded QoS under high channel load.

[0055] The present disclosure identifies that an SL positioning session typically involves multiple UEs. This differs from SL communication, which is typically between two UEs. An SL positioning session may also involve exchange of SL PRS or positioning-related messages between the multiple UEs. Moreover, different UEs may use different cast types, e.g. unicast/groupcast/broadcast, within a single session. As an example, for sidelink time difference of arrival (SL-TDOA) positioning method (DL-TDOA-like), multiple anchor UEs would transmit SL PRS to a target UE. The target UE may be considered as a UE to be positioned (i.e. a UE whose position or location is to be determined), and an anchor UE may be considered as a UE that supports the positioning of the target UE. When outside of network coverage, in some examples UEs may use a UE-autonomous scheme, and the configuration and resource allocation of the transmissions can be determined or coordinated by the target UE or another UE, without any gNB or location management function (LMF) involvement. The present disclosure identifies that such settings in SL positioning may open-up new possibilities to combat congestion.

[0056] Thus, as will be described in more detail below, the present disclosure proposes, inter alia, a new mechanism and related signaling, which performs congestion control during SL positioning of a target UE. In examples, the congestion control mechanism enables positioning support to be coordinated between multiple anchor UEs. For example, a positioning support load (such as bandwidth allocation and/ or periodicity) may be distributed or offloaded (partially or fully) from one or more anchor UEs that are experiencing relatively high congestion to one or more anchor UEs that are experiencing relatively low congestion. In other words, anchor UEs with low congestion can provide assistance to the positioning effort, to reduce the burden on highly congested UEs. In examples, spatial distribution (i.e. location diversity) amongst anchor UEs may be leveraged to improve positional accuracy. For example, positioning accuracy may be enhanced in congested situations by offloading the SL congestion over the spatial domain depending on the dynamic load conditions at different locations that the anchor UEs reside (e.g. from overloaded areas to under-loaded areas). In some examples, the concept is referred to as SL Positioning Congestion Control (SPCC).

[0057] Thus, for a group of UEs participating in a SL positioning session to position a target UE, SL PRS configuration of a UE may be determined based at least on the congestion level measurement (such as CBR and CR), and location of one or more of the UEs in the session. Two main schemes are broadly proposed:

1 . A centralized scheme involving a coordinator entity. The coordinator entity could be a UE, such as the target UE. The coordinator entity could also be another UE such as an anchor UE. The coordinator could also be a network entity, such as an LMF or gNB. In examples, the coordinator entity configures SL PRS for each UE in the session that transmits SL PRS, e.g. anchor UEs. Here, each anchor UE reports its channel congestion level to the coordinating entity. Each anchor UE may also report its own location to the coordinator entity. Where the anchor UEs report their location as well as congestion level, this enables the location information to be used to determine how useful an anchor UE may be to the positioning procedure of the target UE. For example, if a lot of anchor UEs are located close to each other, then spreading the SL PRS load to another UE that is located elsewhere may be more useful than spreading the load to another co-located anchor UE. This is because in some examples positioning accuracy of the target UE is optimized where there is a geographical spread of the anchor UEs.

2. A distributed scheme, where each anchor UE that transmits SL PRS in the positioning session autonomously determines its own SL PRS configuration. For example, each anchor UE may autonomously determine its own SL PRS configuration based on a (pre-)configured rule. For example, the (pre-) configured rule may be a mapping rule which maps congestion level and geographical area of a UE and other UEs to SL PRS configuration of the UE. Here, each UE reports its channel congestion level and location to all the other member UEs. In some examples of the distributed scheme, a UE (e.g., target UE) collects congestion- related measurements from all UEs and distributes this information to each UE (e.g., groupcasts all measurements).

[0058] Figure 1 schematically shows a system comprising a target UE 102 and anchor UEs 104 and 106. Of course, in practice there may be more than two anchor UEs. UEs may also be referred to as user devices. A network entity is also shown at 108. For example, the network entity 108 may comprise an LMF or a gNB. For the purpose of the foregoing, it may be assumed that there is an SL positioning session in which the anchor UEs 104 and 106 transmit SL PRS messages to help with positioning of the target UE 102. As mentioned above, the anchor UEs 104 and 106 may also transmit messages related to their position. The network or the coordinator entity may then determine which positioning scheme to use (i.e. centralized or distributed). The network or coordinator entity may then transmit the information of which scheme to use to any UEs joining the session. In some examples the session is (pre-) configured with SPSCC enable/disable conditions that depend on at least the number of anchor UEs in the session.

[0059] The centralized and distributed schemes are discussed in more detail in-turn below. Centralized scheme

[0060] Reference is first made to Figure 2, which shows communication between a coordinator entity 202 (in this case a target UE), a first anchor UE 204 (UE1) and a second anchor UE 206 (UE2).

[0061] During a sidelink positioning session, the first anchor UE 204 and the second anchor UE 206 transmit SL PRS to the target UE 202 (coordinator UE) based on a first SL PRS configurations (e.g., Config1_A, Config2_A). This is shown at S201 and S202. In some examples, the intended receiver of SL PRS (e.g., the target UE 202) conducts positioning- related measurements on the SL PRS. These measurements may include one or more of time-based measurements (for example, time of arrival); phased-based measurements (for example carrier phase measurements); angular based measurements (for example angle of arrival); and/or power-based measurements (for example RSRP reference signal received power). In some examples, the SL PRS are transmitted according to SL PRS configurations that are pre-configured in the anchor UEs 204 and 206. In this example, initially anchor UE 204 is using an SL_PRS configuration Config1_A, and anchor UE 206 is using an SL_PRS configuration Config2_A. [0062] At S203 and S204, the first anchor UE 204 and the second anchor UE 206 report information including congestion-related metrics to the coordinator UE 202. For example, the congestion related metrics may comprise one or more of SL CBR and CR. In the example of Figure 2, anchor UE 204 is reporting a high congestion value, and anchor UE 206 is reporting a low congestion value. The anchor UEs 204 and 206 may also report their location to the target UE 202. In some examples, the reporting by the anchor UEs 204 and 206 may be periodic. In some examples the reporting by the anchor UEs 204 and 206 is event-triggered. For example, a triggering event may be a request by the coordinator UE 202. A triggering event may additionally or alternatively be a channel congestion threshold being reached. The threshold may be (pre-) configured by the coordinator UE 202 or the network.

[0063] At S205, based on the information received from the anchor UEs 204 and 206, the coordinator UE determines updated or new SL PRS configurations (e.g., second SL PRS configuration (Config1_B, Config2_B) for the anchor UEs 204 and 206. For example, for the anchor UEs that report high level of congestion (e.g., high CBR and high CR), the coordinator UE 202 may change or alter the configuration to an SL PRS configuration with a reduced bandwidth and/or periodicity of SL PRS transmission, reporting frequency. Likewise, for anchor UEs that report low level of congestion (e.g., low CBR and low CR), the coordinator UE 202 may increase SL PRS bandwidth and/or periodicity of SL PRS transmission. The coordinator UE 202 may consider positioning-related measurements, that were measured by using SL PRSs of S201 and S202, when determining the new SL PRS configurations. For example, based on the current measurements, if the target UE cannot satisfy its positioning QoS requirements (e.g., accuracy, latency), it may configure new SL PRS with higher bandwidth and/or frequency.

[0064] In some examples, one or more other entities may determine new SL PRS configurations. The intended receiver of the SL PRS transmissions may report its measurements and/or provide feedback on the transmissions (e.g., as indicative of an increase/decrease in bandwidth, frequency, and/or power etc.).

[0065] The new configurations are transmitted to the first anchor UE 204 and second anchor UE 206 at S206 and S207 respectively. For example at S206, a configuration Config1_B is sent to anchor UE 204, and the Config1_B may be a lower bandwidth than Config1_A. Likewise at S207 a Config2_B is sent to anchor UE 206, and the Config2_B may be a higher bandwidth than Config2_A.

[0066] The anchor UEs 204 and 206 then transmit subsequent SL PRS in accordance with the updated configurations (Config1_B and Config2_B), as shown at S208 and S209.

[0067] Figure 3 shows another example of the centralized scheme. In the example of Figure 3 the coordinator entity is a network entity such as an LMF or a gNB 308. [0068] At S301 and S302, the first anchor UE 304 and the second anchor UE 306 report information including congestion-related metrics to the coordinator entity 308. For example, the congestion related metrics may comprise one or more of SL CBR and CR. The anchor UEs 304 and 306 may also report their location to the coordinator entity 308. In the example of Figure 3, anchor UE 304 is reporting a high congestion value, and anchor UE 306 is reporting a low congestion value. In some examples, the reporting by the anchor UEs 304 and 306 may be periodic. In some examples the reporting by the anchor UEs 304 and 306 may be event-triggered. For example, a triggering event may be a request by the coordinator entity 308. A triggering event may additionally or alternatively be a channel congestion threshold being reached. The threshold may be (pre-)configured by the coordinator entity 302 or the network.

[0069] At S303, based on the information received from the anchor UEs 304 and 306, the coordinator entity 308 determines updated or new SL PRS configurations (second SL PRS configurations (e.g., Config1_B and Config2_B) forthe anchor UEs 304 and 306. For example, for the anchor UEs that report high level of congestion (e.g., high CBR and high CR), the coordinator entity 308 may change or alter the configuration to an SL PRS configuration with a reduced bandwidth and/or periodicity of SL PRS transmission. Likewise, for anchor UEs that report low level of congestion (e.g., low CBR and low CR), the coordinator entity 308 may increase SL PRS bandwidth and/or periodicity of SL PRS transmission.

[0070] The new SL PRS configurations are transmitted to the first anchor UE 304 and second anchor UE 306 at S304 and S305, respectively. For example, at S304, a configuration Config1_B is sent to anchor UE 304. For example, Config1_B may be a lower bandwidth than Config 1_A. Likewise at S305 a Config2_B is sent to anchor UE 306. Config2_B may be a higher bandwidth than Config2_A.

[0071] In some examples, in addition to or alternative to SL PRS configurations of existing anchor UEs being modified, the coordinator entity (e.g. UE or LMF or gNB) may decide to suspend (or mute or deactivate) SL PRS transmission of a specific anchor UE, and/or trigger (or initiate or enable) and configure SL PRS transmission of a new UE that was not previously within the session.

[0072] For example, an anchor UE may be in a stand-by mode. In this context, by “stand-by mode” is meant that the UE is standing by to send SL PRS. In some examples, stand-by anchors are chosen along with “active” anchors during anchor selection. A stand-by anchor acts as anchor to the session only when activated/triggered. Then, the coordinator entity may decide to deactivate a specific anchor UE and activate the stand-by anchor UE instead, for example based on the CBR measurements and/or location of the active UE and the stand-by UE. Error! Reference source not found, illustrates such a scenario, which shows communication between a coordinator entity 402 (e.g UE or LMF or gNB), a first anchor UE 404 and a second anchor UE 406. In the example of Figure 4 anchor UE 406 is considered to be a stand-by anchor UE that is experiencing a low CBR.

[0073] At S401 , the coordinator entity 402 sends a stand-by indication to anchor UE 406, informing UE 406 that it is a stand-by anchor UE.

[0074] As shown at S402, the anchor UE 404 is sending SL PRS to coordinator entity 402, for example according to a first SL PRS configuration (e.g., Config1_A). The coordinator entity may perform positioning-related measurements based on the SL PRS, and this may be used at S405 afterward.

[0075] At S403 and S404 the anchor UE 404 and stand-by anchor UE 406 are sending information related to congestion related metrics to the coordinator entity 402. For example, the metrics includes SL CBR and/or CR. In the example of Figure 4, anchor UE 404 reports high value congestion metrics and anchor UE 406 reports low value congestion metrics. The anchor UE 404 and stand-by anchor UE 406 may also send information of their location at this stage.

[0076] At S405, the coordinator entity 402 determines new SL PRS configurations (e.g., second SL PRS configurations) for the anchor UEs. In this example, the coordinator entity 402 determines that stand-by anchor UE 406 is more suitable than active anchor 404 (for example because anchor 404 had higher congestion than anchor 406, and/or because anchor 404 was located in a less optimal position than stand-by anchor 406). In some embodiments, at S405, the coordinator entity may not change the SL PRS configuration that was configured to the standby UE, and the coordinator may activate the standby UE without further configuration.

[0077] Accordingly, at S406 the coordinator entity 402 sends a notification to anchor UE 404, to deactivate anchor UE 404.

[0078] At S407 the coordinator entity 402 sends a notification to stand-by anchor 406, to activate UE 406 into an active anchor role. At this stage (or in a separate stage), the coordinating entity 402 may also send an SL PRS configuration to anchor UE 406 (e.g. Config2_A or Config 2_B). In this case, the SL PRS configuration may be the updated/new SL PRS configuration or old SL PRS configuration. Alternatively, the UE 406 may have been preconfigured with an SL PRS configuration to employ once activated. Alternatively, the coordinator entity 402 only transmits the activation notification to the standby UE, and the standby UE may transmit the SL PRS based on pre-configured SL PRS configuration.

[0079] Then, at S408 the anchor 406 (which is now active and no longer stand-by) begins sending SL PRS to coordinator entity 402, in accordance with its SL PRS configuration. Distributed scheme

[0080] Reference is made to Figure 5, which shows communication between a target UE 502, a first anchor UE 504 and a second anchor UE 506. [0081] As shown at S501 and S502, the anchor UEs are sending SL PRS to target UE 502. For example, the SL PRS may be sent according to first SL PRS configurations that have been (pre-)configured in the anchor UEs 504 and 506. For example, anchor UE 504 is transmitting SL PRS according to a configuration Config1_A, and anchor UE 506 is transmitting SL PRS according to a configuration Config2_A. The target UE 502 may perform positioning-related measurements based on the SL PRSs received at S501 and S502, and this measurement result may be used for determining new SL PRS configurations.

[0082] In contrast to the centralized mechanism, in the distributed scheme the anchor UEs 504 and 506 do not report congestion related metrics back to target UE 502. Rather, in the distributed scheme the anchor UEs in a session (or at least some of them) share the congestion related metrics with each other.

[0083] In the example of Figure 5, anchor UE 504 reports congestion related metrics to anchor UE 506, and vice versa. For example, the congestion related metrics may comprise one or more of SL CBR and CR. In the example of Figure 5, anchor UE 504 is experiencing high values of congestion and anchor UE 506 is experiencing low values of congestion. The anchor UEs 504 and 506 may also share their location information with each other. At S505, the target UE may transmit a measurement report and/or feedback on SL PRS transmissions to the anchor UE’s 504, 506. These may be separately reported or reported together.

[0084] Based on the information received at S504 and/or at S505, the anchor UE 504 determines a new SL PRS configuration (i.e. , the second SL PRS configuration (Config1_B)) for itself at S506. In addition, SL PRS configuration determination may also consider QoS requirement of the target UE.

[0085] Based on the information received at S503 and/or at S505, the anchor UE 506 determines a new SL PRS configuration (i.e., the third SL PRS configuration (Config2_B)) for itself at S507. In addition, SL PRS configuration determination may also consider QoS requirement of the target UE.

[0086] At S508 the anchor UE 504 informs the target UE 502 of its new SL PRS configuration (Config 1_B). For example, the new configuration may have a lower bandwidth than Config1_A (since anchor UE 504 was experiencing high congestion). For example, the new configuration may be considered Config1_B, which is different from Config1_A.

[0087] At S509 the anchor UE 506 informs the target UE 502 of its new SL PRS configuration (Config 2_B). For example, the new configuration may have a higher bandwidth than Config2_A (since anchor UE 506 was experiencing low congestion). For example, the new configuration may be considered Config2_B, which is different from Config2_A.

[0088] As shown at S510 and S511 , the anchor UE 504 and anchor UE 506 begin sending SL PRSs to target UE 502 with their new configurations, respectively. [0089] Reference is made back to S506 and S507, where each anchor UE 504 and 506 determines a new SL PRS for itself. As discussed, in some examples each anchor UE 504 and 506 does this autonomously, for example without being sent a new SL PRS configuration from a coordinator entity. [0090] In some examples, each anchor UE stores a mapping rule, and uses this mapping rule when determining the new SL PRS configuration. In some examples the mapping rule is stored at each anchor UE 504 and 506 as a look-up-table (LUT). An example LUT is shown in Table 1 below.

Table 1 : SL PRS Config and CBR mapping table

[0091] As shown, the table maps different SL PRS configurations (e.g. bandwidth and periodicity) to different congestion metric values (e.g. CBR or CR) of the UE that is using the mapping table (e.g. an anchor UE), and different percentages of other UEs (e.g. other anchor UEs) in the SL positioning session (for example based on percentage of other anchor UEs with a congestion metric (e.g. CBR or CR) below a certain threshold).

[0092] Take an example where anchor UE 504 wants to determine the SL PRS configuration that it needs to apply. In this example, say 0 to 25% of anchor UEs in the session have a congestion metric (e.g. SL CBR) below a certain threshold (e.g. 0.75). In some examples, anchor UE 504 will have learnt this information by communication with other anchor UEs (e.g. anchor UE 506). Then, the first row in column 1 of the table would be looked at. Then, say for example that the anchor UE 504 is experiencing a congestion metric that is CBR_level_2 (e.g. 0.34 to 0.66). Then the anchor UE 504 looks to the second sub-row within the first row of the second column of the table (CBR_level_2 (e.g. 0.34 to 0.66). Then, reading along the table, anchor UE 504 determines that it needs to apply SL_PRS Config_2. Other anchor UEs e.g. anchor UE 506 will perform a similar process.

[0093] Thus, it will be appreciated that in some examples an anchor UE collects CBR info of other UEs (for example other anchor UEs) to determine related PRS configuration. In another example, the congestion metric information (e.g. CBR or CR) of other UEs may be collected by an anchor UE from a centralized entity (e.g., gNB or LMF).

[0094] In some examples, the mapping table itself, and for example the pre-determined thresholds therein, is determined by a network entity such as an LMF. In other examples the content of the mapping table may be determined by a gNB or a UE, and then shared with other entities such as anchor UEs.

[0095] In some examples, the mapping table may also consider the spatial distribution of anchor UEs. For example, the mapping table may have a column that contains information of relative location of the target UE to each anchor UE (e.g. distance from each other, direction etc.). For example, the spatial distribution of UEs may be represented by relative and/or absolute location of UEs. Values may be provided in metres, in some examples (though of course other units such as cm, km etc. may be used). In some examples the information of spatial distribution is dynamically updated to account for mobile UEs. In some examples the updating is periodic. In some examples the updating is trigger based e.g., upon a UE moving a distance greater than a threshold value, X m.

[0096] In some examples, the mapping table may also consider the QoS requirement of target UE. For example, the mapping table may have a column that indicates QoS level of the target UE. The QoS parameters may include, e.g., accuracy and/or latency.

[0097] In some examples the information of spatial distribution of anchor UEs comprises Geometric Dilution of Precision (GDOP) information.

[0098] In some examples an inter-UE distance between anchor UEs may be considered. For example, the first column in Table 1 could then include additional information such as, “% of other UEs with SL CBR below a threshold SL CBR_thr_1 (e.g. 0.75) and average inter-UE distance above a certain threshold (e.g. 50m)”.

[0099] In some examples, Table 1 (or a similar Table), could also be used in the centralized scheme. For example, where new SL PRS values are determined at S205 in Figure 2 or S303 in Figure 3, Table 1 (or a similar Table) may be used.

[0100] In some examples, one aspect of a selected SL PRS configuration comprises transmit power. That is, according to some examples a transmit power of SL PRS by an anchor UE is dependent on a chosen configuration.

[0101] It will be appreciated that the proposed concepts allow a target UE to position itself with high accuracy, even when one or more of its anchor UEs face higher SL congestion. That is, according to some examples, adaptation of an SL positioning session is performed, to reduce or mitigate the effect of SL congestion at one or more anchor UEs on performance of the session.

[0102] Figure 6 illustrates an example of a terminal 600. The terminal 600 may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a user device, user equipment, a mobile station (MS) or mobile device such as a mobile phone or what is known as a ’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, an Internet of things (loT) type communication device or any combinations of these or the like. The terminal 600 may provide, for example, communication of data for carrying communications. The communications may be one or more of voice, electronic mail (email), text message, multimedia, data, machine data and so on.

[0103] The terminal 600 may receive signals over an air or radio interface 607 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 6 transceiver apparatus is designated schematically by block 606. The transceiver apparatus 606 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

[0104] The terminal 600 may be provided with at least one processor 601 , at least one ROM 602a, at least one RAM 602b and other possible components for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 604.

[0105] The device may optionally have a user interface such as keypad 605, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display 608, a speaker and a microphone may be provided depending on the type of the device.

[0106] UEs, such as target UEs and anchor UEs discussed in Figures 1 to 5 may take the form of a UE as schematically shown in Figure 6.

[0107] Figure 7 shows an example of a control apparatus for a communication system, for example to be coupled to and/or for controlling a station of an access system, such as a RAN node, e.g. a base station, gNB, a central unit of a cloud architecture ora node of a core network such as an MME or S-GW, a scheduling entity such as a spectrum management entity, an LMF or a server or host. The control apparatus may be integrated with or external to a node or module of a core network or RAN. In some embodiments, base stations comprise a separate control apparatus unit or module. In other embodiments, the control apparatus can be another network element such as a radio network controller or a spectrum controller. In some embodiments, each base station may have such a control apparatus as well as a control apparatus being provided in a radio network controller. The control apparatus 700 can be arranged to provide control on communications in the service area of the system. The control apparatus 700 comprises at least one memory 701 , at least one data processing unit 702, 703 and an input/output interface 704. Via the interface the control apparatus can be coupled to a receiver and a transmitter of the base station. The receiver and/or the transmitter may be implemented as a radio front end or a remote radio head. For example, the control apparatus 700 or processor 701 can be configured to execute an appropriate software code to provide the control functions. A network entity, such as an LMF or gNB, discussed with respect to e.g. Figure 1 and Figure 3 may take the form of a control apparatus as shown in Figure 7.

[0107] Figure 8 is a flow chart of a method according to an example. The flow chart of Figure 8 may be viewed from the perspective of an apparatus. For example, the apparatus may be a coordinator entity. The coordinator entity may be or provided in a UE (e.g., a target UE; an anchor UE) or may be or provided in a network entity (e.g., an LMF; gNB). As shown at S801 , the method comprises obtaining congestion information related to a sidelink positioning. As shown at S802, the method comprises determining, based on the obtained congestion information, sidelink positioning reference signal configuration information to be used for the sidelink positioning. Figure 8 describes parts of the signal flows of Figures 2 to 5, and the other parts of Figures 2 to 5 can be adapted to Figure 8.

[0108] Figure 9 shows a schematic representation of non-volatile memory media 900a (e.g. computer disc (CD) or digital versatile disc (DVD)) and 900b (e.g. universal serial bus (USB) memory stick) storing instructions and/or parameters 902 which when executed by a processor allow the processor to perform one or more of the steps of the method of Figure 8. [0109] It should be understood that the apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and/or reception. Although the apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities.

[0110] It is noted that whilst some embodiments have been described in relation to 5G networks, similar principles can be applied in relation to other networks and communication systems. Therefore, although certain embodiments were described above by way of example with reference to certain example architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein.

[0111] It is also noted herein that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

[0112] 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.

[0113] In general, the various embodiments may be implemented in hardware or special purpose circuitry, software, logic or any combination thereof. Some aspects of the disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0114] 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 (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0115] 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.

[0116] The embodiments of this disclosure may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and/or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computerexecutable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it.

[0117] Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The physical media is a non-transitory media.

[0118] 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).

[0119] The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

[0120] Embodiments of the disclosure may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

[0121] The scope of protection sought for various embodiments of the disclosure is set out by the independent claims. The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the disclosure.

[0122] The foregoing description has provided by way of non-limiting examples a full and informative description of the exemplary embodiment of this disclosure. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this disclosure will still fall within the scope of this invention as defined in the appended claims. Indeed, there is a further embodiment comprising a combination of one or more embodiments with any of the other embodiments previously discussed.

Claims

1. An apparatus comprising: means for obtaining congestion information related to a sidelink positioning; and means for determining, based on the obtained congestion information, sidelink positioning reference signal configuration information to be used for the sidelink positioning.

2. An apparatus according to claim 1 , comprising means for obtaining location information of one or more user devices for determining the sidelink positioning reference signal configuration information.

3. An apparatus according to claim 1 or claim 2, wherein the congestion information comprises one or more of: channel busy ratio; channel occupancy ratio.

4. An apparatus according to claim 2 or claim 3, wherein the congestion information indicates that a first user device of the one or more user devices is experiencing a relatively high level of congestion and a second user device of the one or more user devices is experiencing a relatively low level of congestion.

5. An apparatus according to claim 4, wherein the sidelink positioning reference signal configuration information is configured for reducing the usage of radio resources at the first user device.

6. An apparatus according to claim 4 or claim 5, wherein the sidelink positioning reference signal configuration information is configured for increasing the usage of resources at the second user device.

7. An apparatus according to any of claims 4 to 6, wherein the second user device comprises a stand-by user device to the sidelink positioning, and the apparatus comprises means for causing the second user device to become active in the sidelink positioning.

8. An apparatus according to any of claims 1 to 5, wherein the sidelink positioning reference signal configuration information for one or more user devices comprises at least one transmission parameter, the at least one transmission parameter comprising at least one of: bandwidth; transmission frequency; transmission power.

9. An apparatus according to any of claims 1 to 8, wherein the apparatus comprises means for storing a mapping table for use when performing the determining sidelink positioning reference signal configuration information.

10. An apparatus according to claim 9, wherein the mapping table provides a mapping of a congestion level at the apparatus to a percentage of one or more user devices experiencing a congestion level below a threshold, and a mapping to sidelink positioning reference signal configuration information to be selected.

11. An apparatus according to any of claims 1 to 10, wherein the apparatus comprises a coordinating apparatus that comprises means for determining sidelink positioning reference signal configuration information for a plurality of respective user devices to use when transmitting positioning reference signals in the sidelink positioning.

12. An apparatus according to claim 11 , comprising one of: a target user equipment to be positioned; a base station; a location management function.

13. An apparatus according to any of claims 1 to 10, wherein the apparatus comprises an anchor user device in the sidelink positioning.

14. An apparatus according to claim 13, wherein the anchor user device comprises means for determining sidelink positioning reference signal configuration information for the anchor user device itself to use when transmitting positioning reference signals in the sidelink positioning.

15. An apparatus according to any of claims 1 to 14, comprising means for receiving the congestion information.

16. A method, comprising: obtaining congestion information related to a sidelink positioning; and determining, based on the obtained congestion information, sidelink positioning reference signal configuration information to be used for the sidelink positioning.

17. The method according to claim 16 further comprising obtaining location information of one or more user devices for determining the sidelink positioning reference signal configuration information.

18. The method according to claim 16 or claim 17, wherein the congestion information comprises one or more of: channel busy ratio; channel occupancy ratio.

19. The method according to claim 17 or claim 18, wherein the congestion information indicates that a first user device of the one or more user devices is experiencing a relatively high level of congestion and a second user device of the one or more user devices is experiencing a relatively low level of congestion.

20. The method according to claim 19, wherein the sidelink positioning reference signal configuration information is configured for reducing the usage of radio resources at the first user device.

21. The method according to claim 19 or claim 20, wherein the sidelink positioning reference signal configuration information is configured for increasing the usage of resources at the second user device.

22. The method according to any of claims 16 to 21 , further comprising determining, by a coordinating apparatus, sidelink positioning reference signal configuration information for a plurality of respective user devices to use when transmitting positioning reference signals in the sidelink positioning.

23. The method according to claim 16 to 21, further comprising determining, by an apparatus in an anchor user device, sidelink positioning reference signal configuration information for the anchor user device itself to use when transmitting positioning reference signals in the sidelink positioning.

24. A computer program comprising instructions for causing an apparatus to perform at least the following: obtaining congestion information related to a sidelink positioning; and determining, based on the obtained congestion information, sidelink positioning reference signal configuration information to be used for the sidelink positioning.