EP4691120A1

EP4691120A1 - A method for enabling sidelink positioning, related wireless devices, and a related radio network node

Info

Publication number: EP4691120A1
Application number: EP24707518.7A
Authority: EP
Inventors: Basuki PRIYANTO; Anders Berggren; Yujie Zhang
Original assignee: Sony Europe BV; Sony Group Corp
Current assignee: Sony Europe BV; Sony Group Corp
Priority date: 2023-04-05
Filing date: 2024-02-23
Publication date: 2026-02-11
Also published as: CN120958931A; WO2024208485A1

Abstract

Disclosed is a method, performed in a first wireless device for enabling sidelink positioning. The method comprises receiving, from a second wireless device, a sidelink reference signal for positioning. The method comprises transmitting, to the second wireless device, positioning feedback information indicative of a quality of the received sidelink reference signal for positioning.

Description

A METHOD FOR ENABLING SIDELINK POSITIONING, RELATED WIRELESS DEVICES, AND A RELATED RADIO NETWORK NODE

The present disclosure pertains to the field of wireless communications. The present disclosure relates to a method for enabling sidelink positioning, a related first wireless device, a related second wireless device, and a related radio network node. BACKGROUND

Sidelink positioning is currently discussed in 3GPP Rel-18. Sidelink positioning is a mechanism where at least two wireless devices (WDs) can perform positioning estimation based on a positioning measurement in a first WD. The positioning measurement itself is based on a received sidelink reference signal for positioning transmitted by a second WD and received by the first WD.

There are at least two WDs involved in sidelink positioning, one is the WD transmitting the sidelink reference signals for positioning, which may herein be referred to as a sidelink transmitting wireless device (SL-Tx-WD), and the other one is the WD receiving the sidelink reference signal for positioning, which may herein be referred to as a sidelink reference signal receiving WD (SL-Rx-WD). The SL-Tx-WD transmits sidelink reference signals for positioning in a sidelink resource (such as a resource within a sidelink resource pool) and the SL-Rx-WD received the sidelink reference signal for positioning and may perform a positioning measurement, such as a timing difference measurement, a received signal strength measurement, and an angle-based measurement. The positioning measurement result can be further processed by the SL-Rx-WD (for example to obtain a relative distance) or it can also be reported to one or more other entity/entities, such as to the SL-Tx-WD, another WD, and/or to a network node.

Ideally, the transmission from the SL-Tx-WD to SL-Rx-WD results in a good positioning measurement, such that a positioning estimation can be accurately obtained. However, due to the nature of radio propagation, a good positioning measurement result may not always be obtained. Limited transmit power, limited bandwidth transmission, blocking or an obstacle between both WDs, a long distance between WDs are among the factors that may negatively affect the positioning measurement. The positioning estimation based on bad positioning measurement results in inaccurate positioning estimation. Hence, the positioning estimation may not be useful at all for determining the positioning of the WD.

SUMMARY

Accordingly, there is a need for devices and methods for enabling sidelink positioning, which may mitigate, alleviate, or address the shortcomings existing and may provide an improved positioning accuracy of the WD.

Disclosed is a method, performed in a first WD for enabling sidelink positioning. The method comprises receiving, from a second WD, a sidelink reference signal for positioning. The method comprises transmitting, to the second WD, positioning feedback information indicative of a quality of the received sidelink reference signal for positioning.

Further, a first WD comprising memory circuitry, processor circuitry, and a wireless interface is provided. The first WD is configured to perform any of the methods disclosed herein.

It is an advantage of the present disclosure that the first WD can inform the second WD and/or a network node about the quality of the received signal which enables the WD to, based on the quality, initiate a retransmission of the sidelink reference signal for positioning. The first WD may for example inform the first WD and/or the network node that the quality of the received sidelink reference signal for positioning does not meet a quality criterion, which may cause an inaccurate positioning of the first WD. By providing a feedback mechanism which enables the first WD to transmit sidelink positioning feedback information, the second WD is enabled to react on a relatively short notice/period by for example performing a retransmission of the sidelink reference signal for positioning, which can increase the quality of the positioning measurement resulting in improved positioning estimation accuracy.

Disclosed is a method, performed in a second wireless device, for handling sidelink positioning of a first wireless device. The method comprises transmitting, to the first wireless device, a sidelink reference signal for positioning. The method comprises receiving, from the first wireless device, positioning feedback information indicative of a quality of the sidelink reference signal for positioning received by the first wireless device.

Further, a second wireless device comprising memory circuitry, processor circuitry, and a wireless interface is provided. The second wireless device is configured to perform any of the methods disclosed herein.

It is an advantage of the present disclosure that the second WD can be informed by the first WD about the quality of the received reference signal for positioning, which enables the WD to, based on the quality, initiate a retransmission of the sidelink reference signal for positioning. The second WD may for example be informed by the first WD that the quality of the received sidelink reference signal for positioning does not meet a quality criterion, which may cause an inaccurate positioning of the first WD. By providing a feedback mechanism which enables the second WD to receive sidelink positioning feedback information, the second WD can react on a short notice by for example performing a retransmission of the sidelink reference signal for positioning, which can increase the quality of the positioning measurement resulting in improved positioning estimation accuracy.

Disclosed is a method, performed in a radio network node, for enabling sidelink positioning of a first wireless device via a second wireless device. The method comprises providing, to at least one of the first wireless device and the second wireless device, resources for transmission of a sidelink reference signal for positioning. The method comprises receiving, from the at least one of the first wireless device and the second wireless device, positioning feedback information indicative of a quality of the received sidelink reference signal for positioning.

Further, a radio network node comprising memory circuitry, processor circuitry, and a wireless interface is provided. The radio network node is configured to perform any of the methods disclosed herein.

It is an advantage of the present disclosure that the radio network node can be informed by the first WD about the quality of the received reference signal for positioning, which enables the WD to, based on the quality, initiate a retransmission of the sidelink reference signal for positioning. The radio network node may for example be informed or indicated by the first WD that the quality of the received sidelink reference signal for positioning does not meet a quality criterion, which may cause an inaccurate positioning of the first WD. In another example, the radio network node may for example be informed or indicated by the first WD that the first WD require resources for the retransmission of sidelink reference signal for positioning. By providing a feedback mechanism which enables the radio network node to receive sidelink positioning feedback information, the radio network node can react to the feedback information by scheduling a retransmission of the sidelink reference signal for positioning, which can increase the quality of the positioning measurement resulting in improving positioning estimation accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present disclosure will become readily apparent to those skilled in the art by the following detailed description of examples thereof with reference to the attached drawings, in which:

Fig. 1 is a diagram illustrating an example wireless communication system comprising an example network node and example wireless devices according to this disclosure,

Fig. 2 is a flow-chart illustrating an example method, performed in a first wireless device, for enabling sidelink positioning according to this disclosure,

Fig. 3 illustrates an example slot format for transmission of sidelink positioning feedback information according to this disclosure,

Fig. 4 illustrates an example association of slots for transmitting sidelink reference signals and sidelink positioning feedback information according to this disclosure,

Figs. 5A-5B illustrate an example resource mapping for transmission of sidelink positioning feedback information according to this disclosure,

Fig. 6 is a flow-chart illustrating an example method, performed in a second wireless device, for handling sidelink positioning of a first wireless device according to this disclosure,

Fig. 7 is a flow-chart illustrating an example method, performed in a radio network node, for enabling sidelink positioning of a first wireless device via a second wireless device according to this disclosure, Fig. 8 is a block diagram illustrating an example first wireless device according to this disclosure,

Fig. 9 is a block diagram illustrating an example second wireless device according to this disclosure,

Fig. 10 is a block diagram illustrating an example network node according to this disclosure, and

Fig. 11 is a signaling diagram illustrating an example communication between a first wireless device, a second wireless device, and a sidelink resource allocation node according to this disclosure, and

Fig. 12 is a signaling diagram illustrating an example communication between a first wireless device, a second wireless device, and a radio network node according to this disclosure.

DETAILED DESCRIPTION

Various examples and details are described hereinafter, with reference to the figures when relevant. It should be noted that the figures may or may not be drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the examples. They are not intended as an exhaustive description of the disclosure or as a limitation on the scope of the disclosure. In addition, an illustrated example needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular example is not necessarily limited to that example and can be practiced in any other examples even if not so illustrated, or if not so explicitly described.

The figures are schematic and simplified for clarity, and they merely show details which aid understanding the disclosure, while other details have been left out. Throughout, the same reference numerals are used for identical or corresponding parts.

Fig. 1 is a diagram illustrating an example wireless communication system 1 comprising an example radio network node 400, an example core network node 600, and one or more wireless device(s) 300, such as a first WD 300A and a second WD 300B. The first WD 300A may be a target wireless device, and the second WD 300B may be an assisting WD 300B according to this disclosure. In one or more examples, the target wireless device 300A is a moving WD. In one or more examples, the assisting wireless device 300B is a WD having a known, such as a fixed location. As discussed in detail herein, the present disclosure relates to a wireless communication system 1 comprising a cellular system, for example, a 3GPP wireless communication system.

A radio network node disclosed herein refers to a radio access network node operating in the radio access network, such as a base station, an evolved Node B, eNB, gNB in NR. In one or more examples, the RAN node is a functional unit which may be distributed in several physical units. A radio network node has at least one transmission and reception point (TRP) for the communication with the wireless device(s).

A core network, CN, node disclosed herein refers to a network node operating in the core network, such as in the Evolved Packet Core Network, EPC, and/or a 5G Core Network, 5GC. Examples of CN nodes in EPC include a Mobility Management Entity, MME and/or a positioning node, such as a Location Management Function (LMF).

In one or more examples, the CN node is a functional unit which may be distributed in several physical units.

The wireless communication system 1 described herein may comprise one or more wireless devices 300, one or more radio network nodes 400, and/or one or more CN nodes. The radio network nodes may be one or more of a base station, an eNB, a gNB and/or an access point. The one or more WDs 300 may comprise moving WDs, such as vehicles and/or Vulnerable Road Users (VRU)s (pedestrians, bikers, etc.), and WDs having fixed locations, such as Road Side Units (RSU)s, Positioning Reference Units (PRUs).

A WD may refer to a mobile device and/or a user equipment (UE). The one or more wireless devices 300, 300A, 300B may be configured to communicate with the network node 400 via a wireless link (or radio access link) 10. The wireless link 10 may be set up via a Uu interface between the one or more WDs and the radio network node 400.

The core network node 600 may be configured to communicate with the radio network node 400 via a link 12, such as a wired and/or wireless link, and/or with the one or more wireless devices 300, 300A, via the radio network node 400.

The wireless devices 300, 300A, 300B may be configured to communicate directly with each other via a sidelink 20, such as without communicating via the radio network node 400. The sidelink 20 may be a wireless link, such as via a PC5 interface.

Positioning of one or more of the WDs 300 may be performed using different techniques, such as sidelink positioning and/or direct-link positioning. The sidelink positioning uses the PC5 interface, such as the sidelink 20, to communicate sidelink reference signals for positioning between a plurality of WDs 300. The direct-link positioning uses the Uu interface between the WD to be positioned and one or more radio network nodes, such as the wireless link 10.

During sidelink positioning, there are two types of WDs that are interacting, as described in 3GPP TR 38.859 Version 18.0.0. The first type of WD is the WD to be positioned, which may herein be referred to as a target WD. The term target WD can be used for the WD to be positioned both in sidelink positioning and/or direct-link positioning. The second type of WD interacting during the sidelink positioning is a WD supporting positioning of target WD, for example by transmitting and/or receiving reference signals for positioning and/or providing positioning-related information over the SL interface. The second type of WD may herein be referred to as an assisting WD. The assisting WD is a WD assisting the target WD in the positioning procedure. The assisting WD may have a known, such as a fixed location, or may be a moving WD, such as a WD having a position that varies over time. When the assisting WD meets certain requirements, such as when the position and/or location is known or fixed, the assisting WD may be referred to as an anchor WD, in accordance with 3GPP TR 38.859.

During sidelink positioning a sidelink reference signal for positioning is transmitted between the target WD and the assisting WD. The sidelink reference signal for positioning is transmitted by one of the target WD and the assisting WD and received by the other. The WD receiving the sidelink reference signal is herein referred to as the SL-Rx-WD 300A and the WD transmitting the sidelink reference signal is herein referred to as the SL-Tx-WD 300B.

Ideally, the transmission from the SL-Tx-WD 300B to the SL-Rx-WD 300A should result in a good positioning measurement, such that a positioning estimation of the target WD can be accurately obtained. However, due to the nature of radio propagation, a good positioning measurement result may not always be obtained. Limited transmit power, limited bandwidth transmission, blocking or an obstacle between both WDs, and a long distance between the WDs are among the factors that may negatively affect the positioning measurement. The positioning estimation based on bad positioning measurement results in inaccurate positioning estimation. Hence, the positioning estimation may not be useful at all for determining the positioning of the WD.

To improve the positioning accuracy of the target WD, the current disclosure provides a solution where the SL-Tx-WD 300B can be informed whether the SL-Rx-WD 300A can obtain a good positioning measurement result or not. By knowing this information, the SL-Tx-WD 300B can perform necessary actions, such as a retransmission of the sidelink reference signal for positioning. In order for the SL-Tx-WD 300B to obtain this information, a feedback mechanism between the SL-Rx-WD 300A and the SL-Tx-WD 300B is introduced.

A feedback mechanism between WDs in sidelink has been adopted for data communication purposes, such as for indicating a success or failure of a data transmission. This feedback mechanism is based on Hybrid Automatic Repeat Request (HARQ) that has been well deployed in LTE and 5G NR for communication over the Uu interface.

In sidelink communication, HARQ feedback is used to indicate the success or failure of data transmissions between two sidelink WDs, with involving a radio network node, such as in sidelink Mode 1 . When a WD transmits data to another device in sidelink communication, the SL-Tx-WD may employ forward error correction (FEC) and error detection codes (EDC) together with the data package. Subsequently, the SL-Rx-WD may decode the FEC and the EDC to identify a reception status and report it to the SL-Tx-WD using one of three feedback types: acknowledgement (ACK), negative acknowledgement (NACK), or no response. In one or more example methods, the ACK may be reported upon the reception being successful. In one or more example methods, the NACK may be reported upon the reception being unsuccessful. In one more example methods, no response is sent when a sidelink control information (SCI) associated with a data transmission is not decoded successfully.

In case of a NACK or no response, the SL-Tx-WD may perform a HARQ retransmission. However, the HARQ feedback and retransmission mechanism currently only exists for data communication, but not for positioning procedures.

Accordingly, the current disclosure provides a feedback mechanism for transmission of sidelink reference signal transmission from the SL-Rx-WD 300A to the SL-Tx-WD 300B based on the positioning measurement at the SL-Rx-WD 300A of the received sidelink reference signal for positioning transmitted by SL-Tx-WD 300B.

Fig. 2 shows a flow-chart of an example method 100, performed in a first WD according to the disclosure, for enabling sidelink positioning. The first WD is the first WD disclosed herein, such as the SL-Rx-WD 300A of Fig. 1 , Fig. 9, Fig. 12, and Fig. 13.

In one or more example methods, the method 100 comprises providing S101 , to a sidelink resource allocating node, information indicative of the first WD’s capability to transmit positioning feedback information. The information indicative of the first WD’s capability to transmit positioning feedback information may indicate whether the first WD is capable of perform the positioning feedback mechanism or not. In one or more example methods, the information indicative of the first WD’s capability to transmit positioning feedback information is indicative of the first WDs capability to perform a certain measurement (such as RSRP only, but not LOS, or vice versa). In one or more example methods, the information indicative of the first WD’s capability to transmit positioning feedback information comprises the first WD’s capability on processing sidelink reference signals for positioning. The resource allocating node may be a radio network node, such as in sidelink Mode 1 , or the second WD, such as the SL-Tx-WD, in sidelink Mode 2. In one or more example methods, the first WD may provide the information to the radio network node via the second WD.

In one or more example methods, the method 100 comprises obtaining S103 feedback configuration information indicative of a configuration to be used for transmitting positioning feedback information.

In one or more example methods, the feedback configuration information is indicative of one or more of: an availability of a positioning feedback mechanism, whether positioning feedback information is to be transmitted or not, resources for providing positioning feedback information, a positioning measurement type to be used for determining positioning feedback information, and one or more thresholds for transmitting positioning feedback information. The availability of the positioning feedback mechanism may be indicative of whether the positioning feedback mechanism is available to be used in the network, such as whether the positioning feedback mechanism is supported by the network. The information indicative of whether positioning feedback is to be transmitted or not may be indicative of whether the feedback mechanism is activated or not. The positioning measurement type may be indicative of which positioning measurement(s) to be used for the feedback mechanism, such as for determining the quality of the received sidelink reference signal for positioning, when the feedback mechanism is activated. The one or more thresholds for transmitting positioning feedback information may be indicative of thresholds to be used when measuring the quality of the sidelink reference signal for positioning, to determine whether feedback is to be provided and/or what type of feedback to provide in the positioning feedback information. The one or more thresholds may be associated with a respective rule set for determining the quality. For example, the SL-Tx-WD or a radio network node, such as the radio network node serving the first WD, may (pre-)assign the first WD with a specific rule set that is to be used for determining the quality of the received sidelink reference signal for positioning. The rule set to be used can be indicated by an index of the rule set and a corresponding threshold. The index of the rule set can be associated with a respective measurement, such as measurement type. In one or more examples, a first example rule set is associated with a Reference Signal Received Power (RSRP) measurement and may have an RSRP threshold (RSRPth) of for example -70dBm. The first example rule set may be indicated as {rule set #1 with RSRPth = -70dBm}, which indicates that an RSRP measurement is to be performed and that the threshold to be applied to the RSRP measurement is -70dBm. Further thresholds and/or rule sets may be provided and/or indicated for other quality measurements, such as measurements relating to Line-of-Sight (LOS) indicator, first path average ratio (FPAR), amplitude consistency at different antenna elements, and/or phase consistency at different antenna elements. The threshold may be provided as an absolute value or a relative value. The relative value may be a percentage relative to a maximum value. The LOS indicator may be a relative value of the LOS, such as a value between 0 and 1 where 1 is indicative of LOS. In one or more example methods, the positioning feedback information comprises one or more of a power preference, such as a preferred power for the further transmission of sidelink reference signals for positioning, bandwidth (BW) information, bandwidth part (BWP) information, resource pool information, and/or a number of repetitions of the sidelink reference signal for positioning, etc.

In one or more example methods, the feedback configuration information may be obtained by retrieving the feedback configuration information from a database. This may be the case if no instructions are received. The database can be preconfigured and stored within the WD itself.

In one or more example methods, the feedback configuration information may be obtained, such as received, from a second WD, such as from the SL-Tx-WD. In one or more example methods, the feedback configuration information or at least a part of the feedback configuration information, such as the information indicative of the activation of the feedback mechanism and/or the one or more thresholds, can be obtained, such as received, from a network node, such as a radio network node or an LMF. The network node may provide the information indicative of the activation of the feedback mechanism to indicate whether the feedback mechanism is enabled or not in an entire coverage area of the radio network node, and/or to indicate that the feedback mechanism is for certain WDs only. In one or more example methods, the radio network node and/or the LMF may have knowledge of a correspondence between RSRP and a positioning accuracy, based on, for example, historical data. Based on this knowledge, the network node may estimate the threshold, such as a minimum RSRP requirement, to meet a quality criterion, such as a desired positioning accuracy.

In one or more example methods, the feedback configuration information may be received from the second WD and/or the network node, in response to the first WD

In one or more example methods, other measurements on the sidelink reference signal for positioning, such as one or more of FPAR, the LOS indicator and/or NLOS indicator, and the amplitude and/or phase consistency at different antenna elements may be used as a threshold for determining the positioning feedback information, such as the ACK/NACK of the received sidelink reference signal for positioning.

The obtaining step S103 corresponds to the transmitting step S203 performed by the second WD disclosed in relation to Fig. 6 and is similar to the step S901 performed by the radio network node. In other words, the feedback configuration information obtained in step S103 may correspond to the feedback configuration information transmitted in step S203 or the in step S901.

The method 100 comprises receiving S105, from a second WD, a sidelink reference signal for positioning. The sidelink reference signal for positioning may be received with a first sidelink reference signal configuration. The sidelink reference signal configuration may comprise a bandwidth for sidelink reference signals for positioning, a resource allocation, such as a time and/or frequency allocation, and/or different transmit power. In one or more example methods, receiving S105 comprises receiving sidelink reference signals for positioning from a plurality of second WDs. Receiving S105 corresponds to the transmitting step S205 performed by the second WD disclosed in relation to Fig. 6.

In one or more example methods, the method 100 comprises determining S107, based on the received sidelink reference signal, the quality of the received sidelink reference signal for positioning. In one or more example methods, determining comprises performing a positioning measurement to measure the quality of the sidelink reference signal for positioning. The positioning measurement may be one or more of a signal strength measurement, an RSRP measurement, a LOS measurement, and a Time Difference of Arrival (TDOA) measurement, on the received sidelink reference signal for positioning. Upon the measurement result meeting a quality criterion, such as being equal to or above a threshold associated with the measurement, the first WD may determine to provide positive feedback in the positioning feedback information. Upon the measurement result failing to meet the quality criterion, such as being below the threshold associated with the measurement, the first WD may determine to provide negative feedback in the positioning feedback information. The threshold may be the threshold indicated in the feedback configuration information, such as in the one or more rule sets indicated in the feedback configuration information. In one or more example methods, the threshold may be an RSRP threshold.

The method 100 comprises transmitting S109, to the second WD or to a network node, such as the radio network node and/or the LMF, positioning feedback information indicative of a quality of the received sidelink reference signal for positioning. The transmitting step S109 corresponds to the receiving step S207 performed by the second WD disclosed in relation to Fig. 6. In other words, the positioning feedback information transmitted in S109 corresponds to the positioning feedback information received in S207.

The positioning feedback information may be based on the quality and/or the threshold of a positioning measurement and/or a combination of positioning measurement, such as based on RSRP, and/or LOS classifications.

In one or more example methods, the positioning feedback information comprises one or more of: an acknowledgement (ACK) indicating that the quality of the received sidelink reference signal for positioning meets a quality criterion, a non-acknowledgement (NACK) indicating that the quality of the received sidelink reference signal for positioning fails to meet a quality criterion, and a soft value, such as an absolute value indicative of the quality of the received sidelink reference signal for positioning or a relative value indicative of the quality of the received sidelink reference signal for positioning. In one or example methods, the positioning feedback information comprises positive or negative feedback, such as the ACK or the NACK. The positive feedback, such as the ACK, may indicate that the quality of the positioning measurement is meets the quality criterion or is equal to or above the threshold. The positive feedback may be represented in one bit, where “1” means that the positioning measurement is based on LOS or a measurement value, such as an RSRP value, meeting the quality criterion and “0” means NLOS or the measurement value failing to meet the quality criterion. In one or example methods, the positioning feedback information comprises soft- values representing the quality, such as absolute or relative values. For example, a LOS indicator being “0.9” may indicate that the positioning measurement is almost LOS, where 1 indicates LOS.

In one or more example methods, the positioning feedback information is transmitted in a physical sidelink channel dedicated for transmission of positioning feedback information. The physical sidelink channel dedicated for transmission of positioning feedback information may herein be referred to as a physical sidelink positioning feedback channel (PSPFCH)

In one or more example methods, the physical sidelink channel dedicated for transmission of positioning feedback information is associated to one or more WDs and/or one or more sidelink positioning resource occasion.

In one or more example methods, the physical sidelink channel dedicated for transmission of positioning feedback information is allocated in at least one Orthogonal Frequency-Division Multiplexing, OFDM, symbol within a slot containing sidelink reference signals for positioning.

Fig. 3 illustrates an example slot with an OFDM symbol comprising the PSPFCH. The resource, such as the time and/or frequency resource, for transmitting the positioning feedback information from the first WD may be allocated in a new physical channel, such as the PSPFCH, in a sidelink resource within a sidelink resource pool for carrying positioning feedback information (positive or negative) associated with the transmission of sidelink reference signal for positioning. In one or more example methods, the resources associated with the PSPFCH are pre-configured by the radio network node via RRC signaling or DCI to the second WD, such as to the SL-Tx-WD. The second WD may then forward the resource allocation to the first WD, such as in the feedback configuration information. To activate the resources for PSPFCH, the second WD, such as the SL-Tx-WD may indicate in the feedback configuration information that the positioning feedback is enable or disabled, for example via Sidelink Control Information format 2 (SCI-2^nd) carried by a Physical Sidelink Shared Channel (PSSCH) in the slot. The PSPFCH may be allocated in a slot that enables sidelink positioning feedback. The PSPFCH may be separated from the resources allocated for transmission of sidelink reference signals for positioning in a Time Division Multiplexed (TDM) manner, such that the OFDM symbols allocated for the sidelink reference signals for positioning are different than the OFDM symbols allocated for the PSPFCH. In one or more example slots, an Automatic Gain Control (AGC) symbol and a guard symbol is introduced together with the PSPFCH. As can be seen in Fig. 3, in one or more example methods, the AGC symbol may be allocated prior to the PSPFCH, and the guard symbol may be allocated after the PSPFCH symbol. In Fig. 3, the time unit T corresponds to a time duration of one OFDM symbol.

In one or more example methods, the physical sidelink channel dedicated for transmission of positioning feedback information is allocated in every N slot(s) containing sidelink reference signals for positioning, in which N >= 1. In other words, the positioning feedback in PSPFCH can be transmitted periodically once per N slots. In one or more example methods, N can be selected from {1 , 2, 4, 8, 16} etc. The value of N may be dynamically adjusted. For example, a radio network node may configure N = 1 , such that the SL-Tx-WD can receive the positioning feedback frequently in each slot. To allow the first WD, such as the SL-Rx-WD, sufficient time to process the sidelink reference signals for positioning and to transmit positioning feedback information, a minimum slot interval K between the slot comprising sidelink reference signal for positioning and the slot comprising the associated PSPFCH may be defined. For example, if the sidelink reference signal for positioning is transmitted in slot i, then the corresponding PSPFCH should be in a slot equal to or later than slot (i+K) that contains the PSPFCH. The value of K can be selected from various options, such as {1 , 2, 3}, etc. The mapping between the slot with SL-PRS and the associated slot with PSPFCH can be determined by N and K. In one or more example methods, the information indicative of the first WD’s capability to transmit positioning feedback information comprises the first WD’s capability on processing sidelink reference signals for positioning, which may affect the decision of K value. Fig. 4 illustrates an example association between a slot comprising sidelink reference signals for positioning and a corresponding slot with PSPFCH in a slot level. In this example, the periodicity of the PSPFCH is N = 2 and the minimum slot interval K = 2. According to the minimum slot interval, the feedback for the sidelink reference signals for positioning in slot i=1 is supposed to be feedbacked in slot i = 3. However, in the example shown in Fig. 4 no PSPFCH is allocated in slot i = 3. The feedback for the sidelink reference signals for positioning in slot i=1 may therefore be fed back in the next slot having PSPFCH (such as in slot i =4) instead. In such case, one PSPFCH may carry positioning feedback information for the sidelink positioning reference signals from two previous slots.

In one or more example methods, the first WD may transmit positioning feedback information associated with transmissions of sidelink reference signals for positioning from a plurality of SL-Tx-WDs. This may for example be the case for groupcast operation, where the first WD receives sidelink reference signals for positioning from a plurality of SL-Tx-WDs. In one or more example methods, the positioning feedback information for the transmissions from the different SL-Tx-WDs may be Frequency Division Multiplexed (FDMed) or Code Division Multiplexed (CDMed) in one PSPFCH symbol.

In one or more example methods, the PSPFCH is split into multiple segments. Each segment contains multiple feedback Physical Resource Blocks (PRBs) associated with each slot. The number of segments may be determined by, such as based on, a number of subchannels and associated slots in the resource pool. Fig. 5A illustrates an example PSPFCH mapping in which the PSPFCH is split into multiple segments. In the example shown in the Fig. 5A, where one PSPFCH is associated with two slots, such as slots i=1 and i=2, and each slot only has one sub-channel in the frequency domain, the number of segments in the PSPFCH is two (2 slots x 1 subchannel for each slot). In other words, the PSPFCH is split into two segments. A first segment, such as segment #1 of Fig. 5A, may contain positioning feedback information for the sidelink reference signals for positioning transmitted in slot i=1 and subchannel#! , while a second segment, such as segment #2, may contain positioning feedback information for the sidelink reference signals for positioning transmitted in slot i=1 and subchannel#! . The first segment, such as segment #1 , may be allocated with lower PRB indexes than the second segment, such as segment #2, such that the first segment is allocated in lower frequency resources than the second segment.

In one or more example methods, each segment can be further split into multiple PRBs 21 , 22 in the frequency domain and/or code domain (in case of using CDM), carrying ACK/NACK information. Fig. 5B illustrates a split of the first segment 2 and the second segment 22 into multiple PRBs. When the segments are split into multiple PRBs, there may be a one-to- one mapping between the PRBs for positioning feedback information, such as ACK/NACK, and the number of sidelink reference signals for positioning received in the corresponding slot. In other words, if slot i=1 contains sidelink reference signals for positioning from three SL-Tx-WDs, there may be three PRBs in segment #! for transmitting respective positioning feedback information associated with the sidelink reference signals for positioning from three SL-Tx-WDs. The number of PRBs in one PSPFCH segment may be indicated by a parameter M_set. M_set may be calculated by the number of associated resources and the total number of PRBs in PSPFCH. In one or more example methods, M_set is calculated as M_set = floor(M/(N*L)), where M is number of PRBs in PSPFCH, L is the number of associated sub-channels and N is the number of associated slots. In the example shown in Fig. 5A-5B, L = 1 , N = 2. If the total number of PRBs M=100, M_set = 100/(1*2) = 50 PRBs.

In one or more example methods, the mapping between sidelink reference signals for positioning and the PRB index in each segment is determined by an identifier of the first WD, such as the SL-Rx-WD, and an identifier of the second WD, such as the SL-Tx-WD. The respective identifiers may be a Rx WD ID for the first WD and a Tx WD ID for the second WD, which may be carried in the SCI-2^nd via PSSCH. In one or more example methods, there may be a one-to-one mapping between a source ID/destination ID and the PRB ID. For example, the PRB ID = mod(source ID + destination ID, M_set). The source ID herein is the ID of the SL-Tx- WD and the destination ID is the ID of the SL-Rx-WD.

For example, the positioning feedback information for a first sidelink reference signal, in Fig. 5A-5B referred to as SL-PRS#1 , transmitted from a first SL-Tx-WD (such as having a Tx- WD ID = 1 ) to the SL-Rx-WD (such as having a Rx-WD ID = 2) may be carried in PRB #1 of the corresponding segment. For each transmission of sidelink reference signals for positioning, there are two associated IDs (the source ID and the destination ID), which may be carried by SCI-2^nd. The first WD may obtain these two IDs by decoding the SCI-2^nd and may use these two IDs to determine the PRB in which the positioning feedback information is to be transmitted. In one or more example methods, the method 100 comprises, upon the positioning feedback information being indicative of the quality of the received sidelink reference signal for positioning not meeting a quality criterion, receiving S111 , from the second WD, further sidelink reference signal for positioning, such as a retransmission of the sidelink reference signal for positioning. The receiving step S111 corresponds to the transmitting step S209B performed by the second WD disclosed in relation to Fig. 6.

Fig. 6 shows a flow-chart of an example method 200, performed in a second wireless device, WD, according to the disclosure, for handling sidelink positioning of a first WD. The second WD is the second WD disclosed herein, such as the SL-Tx-WD 300B of Fig. 1 , Fig. 9, Fig. 11 , and Fig. 12

In one or more example methods, the method 200 comprises receiving S201 , from the first WD, information indicative of the first WD’s capability to transmit positioning feedback information. The information indicative of the first WD’s capability to transmit positioning feedback information may indicate whether the first WD is capable of perform the positioning feedback mechanism or not. In one or more example methods, the information indicative of the first WD’s capability to transmit positioning feedback information is indicative of the first WDs capability to perform a certain measurement (such as RSRP only, but not LOS, or vice versa, or any other measurement). In one or more example methods, the information indicative of the first WD’s capability to transmit positioning feedback information comprises the first WD’s capability to process sidelink reference signals for positioning. The second WD may forward the information indicative of the first WD’s capability to transmit positioning feedback information to the radio network node. The receiving step S201 corresponds to the providing step S101 performed by the first WD disclosed in relation to Fig. 2. In other words, the information indicative of the first WD’s capability to transmit positioning feedback information received in step S201 corresponds to the information indicative of the first WD’s capability to transmit positioning feedback information provided in step S101.

In one or more example methods, the method 200 comprises transmitting S203, to the first WD, feedback configuration information indicative of a configuration to be used for transmitting positioning feedback information. In one or more example methods, the second WD may receive the feedback configuration information from a radio network node and prior to transmitting the feedback configuration information to the first WD. In one or more example methods, the feedback configuration information is indicative of one or more of an availability of the feedback mechanism, whether positioning feedback information is to be transmitted or not, resources for providing positioning feedback information, a positioning measurement type to be used for determining positioning feedback information, and one or more thresholds for transmitting positioning feedback information. The availability of the positioning feedback mechanism may be indicative of whether the positioning feedback mechanism is available to be used in the network, such as whether the positioning feedback mechanism is supported by the network. The information indicative of whether positioning feedback is to be transmitted or not may be indicative of whether the feedback mechanism is activated or not. The positioning measurement type may be indicative of which positioning measurement(s) to be used for the feedback mechanism, such as for determining the quality of the received sidelink reference signal for positioning, when the feedback mechanism is activated. The one or more thresholds for transmitting positioning feedback information may be indicative of thresholds to be used when measuring the quality of the sidelink reference signal for positioning, to determine whether feedback is to be provided and/or what type of feedback to provide in the positioning feedback information. The one or more thresholds may be associated with a respective rule set for determining the quality.

In one or more example methods, the second WD may (pre-)assign the first WD with a specific rule set that is to be used for determining the quality of the received sidelink reference signal for positioning. The second WD may indicate the rule set to be used by providing an index of the rule set and a corresponding threshold in the feedback configuration information. The index of the rule set can be associated with a respective measurement, such as measurement type. In one or more example methods, thresholds and/or rule sets may be provided and/or indicated for one or more measurements, such as measurements relating to signal strength, RSRP, a LOS indicator, FPAR, amplitude consistency at different antenna elements, and/or phase consistency at different antenna elements. The threshold may be provided as an absolute value or a relative value. The relative value may be a percentage relative to a maximum value. The LOS indicator may be a relative value of the LOS, such as a value between 0 and 1 where 1 is indicative of LOS. The transmitting step S203 corresponds to the obtaining step S103 performed by the first WD disclosed in relation to Fig. 2. In other words, the feedback configuration information transmitted in step S203 corresponds to the feedback configuration information obtained in step S103.

The method 200 comprises transmitting S205, to the first WD, a sidelink reference signal for positioning. The sidelink reference signal for positioning may be transmitted with a first sidelink reference signal configuration. The sidelink reference signal configuration may comprise a bandwidth for sidelink reference signals for positioning, a resource allocation, such as a time and/or frequency allocation, and/or different transmit power. Transmitting S205 corresponds to the receiving step S105 performed by the first WD disclosed in relation to Fig. 2.

The method 200 comprises receiving S207, from the first WD, positioning feedback information indicative of a quality of the sidelink reference signal for positioning received by the first WD.

In one or more example methods, the positioning feedback information is received in a physical sidelink channel dedicated for transmission of positioning feedback information. The positioning feedback information may be based on the quality and/or the threshold of a positioning measurement and/or a combination of positioning measurement, such as based on RSRP, and/or LOS classifications. In one or more example methods, the positioning feedback information comprises one or more of an acknowledgement (ACK) indicating that the quality of the received sidelink reference signal for positioning meets a quality criterion, a non-acknowledgement (NACK) indicating that the quality of the received sidelink reference signal for positioning fails to meet a quality criterion, and a soft value, such as an absolute value indicative of the quality of the received sidelink reference signal for positioning or a relative value indicative of the quality of the received sidelink reference signal for positioning. In one or example methods, the positioning feedback information comprises positive or negative feedback, such as the ACK or the NACK. The positive feedback, such as the ACK, may indicate that the quality of the positioning measurement is meets the quality criterion or is equal to or above the threshold. The positive feedback may be represented in one bit, where “1” means that the positioning measurement is based on LOS or a measurement value, such as an RSRP value, meeting the quality criterion and “0” means NLOS or the measurement value failing to meet the quality criterion. In one or example methods, the positioning feedback information comprises soft-values representing the quality, such as absolute or relative values. For example, a LOS indicator being “0.9” may indicate that the positioning measurement is almost LOS, where 1 indicates LOS.

In one or more example methods, the positioning feedback information is received in the PSPFCH. In one or more example methods, the PSPFCH is associated to one or more WDs and/or one or more sidelink positioning resource occasion.

In one or more example methods, the physical sidelink channel dedicated for transmission of positioning feedback information is allocated in at least one Orthogonal Frequency-Division Multiplexing, OFDM, symbol within a slot containing sidelink reference signals for positioning. The receiving step S207 corresponds to the transmitting step S107 performed by the first WD disclosed in relation to Fig. 2. In other words, the positioning feedback information received in S207 corresponds to the positioning feedback information transmitted in S109 and the PSPFCH corresponds to the PSPFCH described in S109 and in Fig. 3-5B.

In one or more example methods, the method 200 comprises initiating S209, based on the positioning feedback information, a further transmission of sidelink reference signal for positioning. In one or more example methods, the feedback information is used by the second WD, such as the SL-Tx-WD, to initiate further transmission, such as retransmission, of sidelink reference signals for positioning. For example, upon the positioning feedback information being indicative of the quality of the sidelink reference signal for positioning not meeting the quality criterion, such as upon receiving negative feedback, such as a NACK, from the first WD, the second WD may initiate a retransmission of sidelink reference signals for positioning accordingly. The retransmission aims for better positioning accuracy by allowing the first WD to measure on a signal having higher quality. In one or more example methods, initiating S209 comprises sending S209A, to a radio network node, a request for resources for the further transmission of sidelink reference signal for positioning. Upon the positioning feedback information being negative, such as being indicative of the quality of the sidelink reference signal for positioning not meeting the quality criterion, the second WD may determine that a further transmission (retransmission) of sidelink reference signals for positioning is required. The second WD may request resources for the further transmission of sidelink reference signals for positioning from a radio network node, such as from the radio network node serving the first WD and/or the second WD. In one or more example methods, the second WD sends the request to radio network node as soon as it receives the negative feedback, such as the positioning feedback information indicative of the quality of the sidelink reference signal for positioning not meeting the quality criterion.

In one or more example methods, the second WD sends the request to the radio network node prior to the first transmission of sidelink reference signals for positioning, such as sends a request for preconfigured resources for the retransmission. In this case, upon the second WD receiving positive feedback, such as positioning feedback information being indicative of the quality of the sidelink reference signal for positioning meeting the quality criterion, the second WD may send a cancellation of the preconfigured resources to the radio network node, so that the preconfigured resources can be freed up.

In one or more example methods, initiating S209 comprises receiving S209B, from the radio network node, sidelink reference signal configuration for further transmission of sidelink reference signals for positioning, such as a second sidelink reference signal configuration.

In one or more example methods, initiating S209 comprises transmitting S209C, to the first WD, further sidelink reference signal for positioning. In one or more example methods, the second WD transmits the further sidelink reference signals for positioning, such as retransmits the sidelink reference signals for positioning, with the same sidelink reference signal configuration as the first transmission, such as the transmission performed in S205. In one or more example methods, the second WD transmits the further sidelink reference signal, such as the retransmission, with a different sidelink reference signal configuration than the first transmission, such as with a different bandwidth, a different time/frequency allocation, and/or a different transmit power. In one or more example methods, such as when the first transmission of sidelink reference signals for positioning is transmitted to a plurality of first WD, such as a plurality of SL-Rx-WDs, the second WD can selectively retransmit sidelink reference signals for positioning to a subset of the SL-Rx-WDs.

In one or more example methods, the further sidelink reference signals are transmitted in a preconfigured resource for further transmission of the sidelink reference signal for positioning, or in a resource for further transmission of the sidelink reference signal for positioning received from the resource allocating node in response to transmitting the request for resources for the further transmission of sidelink reference signal.

The transmitting step S209B corresponds to the receiving step S111 performed by the first WD disclosed in relation to Fig. 2.

Fig. 7 shows a flow-chart of an example method 900, performed in a radio network node according to this disclosure, for enabling sidelink positioning of a first WD via a second WD. The radio network node is the radio network node disclosed herein, such as radio network node 400 of Fig. 1 , Fig. 10, Fig. 11 , and Fig. 12.

In one or more example methods, the method 900 comprises transmitting S901 , to at least one of the first WD and the second WD, feedback configuration information indicative of a configuration to be used for transmitting positioning feedback information. This information can be provided in higher layer signaling, such as RRC signaling. In one or more example methods, the feedback configuration information is indicative of one or more of an availability of the feedback mechanism, whether positioning feedback information is to be transmitted or not, resources for providing positioning feedback information, a positioning measurement type to be used for determining positioning feedback information, and one or more thresholds for transmitting positioning feedback information. The transmitting step S901 is similar to the obtaining step S103 performed by the first WD disclosed in relation to Fig. 2 and is similar to the transmitting step S203 performed by the second WD.

The method 900 comprises providing S902, to at least one of the first WD and the second WD, first sidelink reference signal configuration. This information can be provided in higher layer signaling, such as RRC signaling. The first sidelink reference signal configuration may be indicative of resources for transmission of a sidelink reference signal for positioning. In one or more example methods, the resources for transmission of a sidelink reference signal for positioning may be comprised in the feedback configuration information transmitted in S901.

In one or more example methods, the method 900 comprises receiving S904, from at least one of the first WD and the second WD, information indicative of the first WD’s capability to transmit positioning feedback information. In one or more example methods, the information indicative of the first WD’s capability to transmit positioning feedback information. The information indicative of the first WD’s capability to transmit positioning feedback information may indicate whether the first WD is capable of perform the positioning feedback mechanism or not. In one or more example methods, the information indicative of the first WD’s capability to transmit positioning feedback information is indicative of the first WDs capability to perform a certain measurement (such as RSRP only, but not LOS, or vice versa, or any other measurement). In one or more example methods, the information indicative of the first WD’s capability to transmit positioning feedback information comprises the first WD’s capability to process sidelink reference signals for positioning. The receiving step S904 corresponds to the providing step S101 performed by the first WD disclosed in relation to Fig. 2.

The method 900 comprises receiving S905, from the at least one of the first WD and the second WD, positioning feedback information indicative of a quality of the received sidelink reference signal for positioning. In one or more example methods, the positioning feedback information comprises a request for resources for a further transmission of a sidelink reference signal for positioning. The positioning feedback information may be received directly from the first WD or via the second WD. This information can be received via lower layer signaling, such as a control channel, a shared channel, or a feedback channel. The receiving step S905 corresponds to the providing step S109 performed by the first WD disclosed in relation to Fig. 2.

In one or more example methods, the method 900 comprises determining S907 a sidelink reference signal configuration for further transmission, such as retransmission, of sidelink reference signal for positioning.

In one or more example methods, the second sidelink reference signal configuration, such as the resources being allocated, is determined in response to receiving the positioning feedback information. In one or more example methods, the sidelink reference signal configuration for further transmission is different to the sidelink reference signal configuration for the first transmission, such as has a different bandwidth, a different time/frequency allocation, and/or a different transmit power.

In one or more example methods, the second sidelink reference signal configuration for further transmission is preconfigured and may be provided with the first sidelink reference signal configuration for transmission of a sidelink reference signal for positioning, transmitted in S902.

In one or more example methods, the method 900 comprises providing S909, to at least one of the first WD and the second WD, the second sidelink reference signal configuration for further transmission of sidelink reference signal for positioning.

Fig. 8 shows a block diagram of an example first wireless device 300A according to the disclosure, such as a SL-Rx-WD. The first WD 300A comprises memory circuitry 301A, processor circuitry 302A, and a wireless interface 303A. The first WD 300A may be configured to perform any of the methods disclosed in Fig. 2. In other words, the first WD 300A may be configured to enable sidelink positioning.

The first WD 300A is configured to communicate with a second WD, such as the second WD disclosed herein, using a wireless communication system.

The first WD 300A is configured to receive (such as via the wireless interface 303A), from the second WD, a sidelink reference signal for positioning.

The first WD 300A is configured to transmit (such as via the wireless interface 303A), to the second WD, positioning feedback information indicative of a quality of the received sidelink reference signal for positioning. The wireless interface 303A is configured for wireless communications via a wireless communication system, such as a 3GPP system, such as a 3GPP system supporting one or more of: New Radio, NR, Long Term Evolution, LTE, Narrow-band loT, NB-loT, and Long Term Evolution - enhanced Machine Type Communication, LTE-M, and 3GPP system operated in licensed bands or unlicensed bands.

The first WD 300A is optionally configured to perform any of the operations disclosed in Fig. 2 (such as any one or more of: S101 , S103, S105, S107, S109, S111). The operations of the first WD 300A may be embodied in the form of executable logic routines (for example, lines of code, software programs, etc.) that are stored on a non-transitory computer readable medium (for example, memory circuitry 301 A) and are executed by processor circuitry 302A.

Furthermore, the operations of the first WD 300A may be considered a method that the first WD 300A is configured to carry out. Also, while the described functions and operations may be implemented in software, such functionality may also be carried out via dedicated hardware or firmware, or some combination of hardware, firmware and/or software.

Memory circuitry 301 A may be one or more of: a buffer, a flash memory, a hard drive, a removable media, a volatile memory, a non-volatile memory, a random access memory (RAM), and any other suitable device. In a typical arrangement, memory circuitry 301A may include a non-volatile memory for long term data storage and a volatile memory that functions as system memory for processor circuitry 302A. Memory circuitry 301 A may exchange data with processor circuitry 302A over a data bus. Control lines and an address bus between memory circuitry 301 A and processor circuitry 302A also may be present (not shown in Fig. 8). Memory circuitry 301A is considered a non-transitory computer readable medium.

Memory circuitry 301 A may be configured to store a sidelink reference signal, a quality of a received sidelink reference signal, feedback configuration information, information indicative of the first WD’s capability to transmit positioning feedback information, further sidelink reference signal for positioning in a part of the memory.

Fig. 9 shows a block diagram of an example second wireless device 300B according to the disclosure, such as a SL-Tx-WD. The second WD 300B comprises memory circuitry 301 B, processor circuitry 302B, and a wireless interface 303B. The second WD 300B may be configured to perform any of the methods disclosed in Fig. 8. In other words, the second WD 300B may be configured to handle sidelink positioning of a first WD.

The second WD 300B is configured to communicate with the first WD using a wireless communication system.

The second WD 300B is configured to transmit (such as via the wireless interface 303B), to the first WD, a sidelink reference signal for positioning. The second WD 300B is configured to receive (such as via the wireless interface 303B), from the first WD, positioning feedback information indicative of a quality of the sidelink reference signal for positioning received by the first WD.

The wireless interface 303B is configured for wireless communications via a wireless communication system, such as a 3GPP system, such as a 3GPP system supporting one or more of: New Radio, NR, Long Term Evolution, LTE, Narrow-band loT, NB-loT, and Long Term Evolution - enhanced Machine Type Communication, LTE-M, and 3GPP system operated in licensed bands or unlicensed bands.

The second WD 300B is optionally configured to perform any of the operations disclosed in Fig. 6 (such as any one or more of: S201 , S203, S205, S207, S209, S209A, S209B). The operations of the second WD 300B may be embodied in the form of executable logic routines (for example, lines of code, software programs, etc.) that are stored on a non-transitory computer readable medium (for example, memory circuitry 301 B) and are executed by processor circuitry 302B.

Furthermore, the operations of the second WD 300B may be considered a method that the second WD 300B is configured to carry out. Also, while the described functions and operations may be implemented in software, such functionality may also be carried out via dedicated hardware or firmware, or some combination of hardware, firmware and/or software.

Memory circuitry 301 B may be one or more of: a buffer, a flash memory, a hard drive, a removable media, a volatile memory, a non-volatile memory, a random access memory (RAM), and any other suitable device. In a typical arrangement, memory circuitry 301 B may include a non-volatile memory for long term data storage and a volatile memory that functions as system memory for processor circuitry 302B. Memory circuitry 301 B may exchange data with processor circuitry 302B over a data bus. Control lines and an address bus between memory circuitry 301 B and processor circuitry 302B also may be present (not shown in Fig. 9). Memory circuitry 301A is considered a non-transitory computer readable medium.

Memory circuitry 301 B may be configured to store positioning feedback information, information indicative of a first WD’s capability to transmit positioning feedback information, feedback configuration, further sidelink reference signal in a part of the memory.

Fig. 10 shows a block diagram of an example radio network node 400 according to the disclosure. The radio network node 400 comprises memory circuitry 401 , processor circuitry 402, and a wireless interface 403. The radio network node 400 may be configured to perform any of the methods disclosed in Fig. 7. In other words, the network node 400 may be configured to enable sidelink positioning of a first WD via a second WD.

The network node 400 is configured to communicate with the first WD and/or the second WD using a wireless communication system. The radio network node 400 is configured to provide (such as, via the wireless interface 403 and/or processor circuitry 402), to at least one of the first WD and the second WD, resources for transmission of a sidelink reference signal for positioning.

The radio network node 400 is configured to receive (such as, via the wireless interface 403), from the at least one of the first WD and the second WD, positioning feedback information indicative of a quality of the received sidelink reference signal for positioning.

The wireless interface 403 is configured for wireless communications via a wireless communication system, such as a 3GPP system, such as a 3GPP system supporting one or more of: New Radio, NR, Long Term Evolution, LTE, Narrow-band loT, NB-loT, and Long Term Evolution - enhanced Machine Type Communication, LTE-M, and 3GPP system operated in licensed bands or unlicensed bands.

Processor circuitry 402 is optionally configured to perform any of the operations disclosed in Fig. 7 (such as any one or more of S301 , S302, S304, S305, S309). The operations of the radio network node 400 may be embodied in the form of executable logic routines (for example, lines of code, software programs, etc.) that are stored on a non-transitory computer readable medium (for example, memory circuitry 401 ) and are executed by processor circuitry 402.

Furthermore, the operations of the radio network node 400 may be considered a method that the radio network node 400 is configured to carry out. Also, while the described functions and operations may be implemented in software, such functionality may also be carried out via dedicated hardware or firmware, or some combination of hardware, firmware and/or software.

Memory circuitry 401 may be one or more of: a buffer, a flash memory, a hard drive, a removable media, a volatile memory, a non-volatile memory, a random access memory (RAM), and any other suitable device. In a typical arrangement, memory circuitry 401 may include a non-volatile memory for long term data storage and a volatile memory that functions as system memory for processor circuitry 402. Memory circuitry 401 may exchange data with processor circuitry 402 over a data bus. Control lines and an address bus between memory circuitry 401 and processor circuitry 402 also may be present (not shown in Fig. 10). Memory circuitry 401 is considered a non-transitory computer readable medium.

Memory circuitry 401 may be configured to store positioning feedback information, a resource configuration, information indicative of the WD’s capability to transmit positioning feedback information in a part of the memory.

Fig. 11 is a signaling diagram illustrating an example communication 500 between a first WD 300A, a second WD 300B, and a network node, such as a radio network node 400 and/or a core network node 600 for positioning, such as an LMF, according to this disclosure. The first WD 300A may be a SL-Rx-WD and the second WD 300B may be a SL-Tx-WD. The signaling from the WD to the LMF may be transparent via the radio network node. In one or more examples, the first WD 300A transmits, to the network node 400, 600, a request 502 for feedback configuration information. The feedback configuration information may be indicative of a configuration to be used for transmitting positioning feedback information 512. In one or more example methods, the feedback configuration information can be indicative of a rule set for determining a quality of a received sidelink reference signal for positioning and/or for transmitting positioning feedback information. In one or more example methods, the feedback configuration information can be indicative of a resource configuration, such as which resource to be used for PSPFCH, a slot format, etc.

In one or more examples, the network node, such as the radio network node 400 and/or the LMF 600, transmits feedback configuration information 503 indicative of a configuration to be used for transmitting the positioning feedback information, to the first WD 300A. In one or more example methods, the feedback configuration information 503 comprises a rule set that is to be used for determining the quality of the received sidelink reference signal for positioning and/or for transmission of the positioning feedback information. In one or more example methods, the feedback configuration information can be indicative of a resource configuration, such as which resource to be used for PSPFCH, a slot format, etc. The feedback configuration information 504 corresponds to the feedback configuration information obtained by the first WD in S103 of Fig. 2.

In one or more examples, the first WD 300A provides (such as, transmits) to the sidelink resource allocating node, information 504 indicative of the first WD’s capability to transmit positioning feedback information. For example, the information 504 indicative of the first WD’s capability to transmit positioning feedback information 512 may comprise the first WD’s capability to process sidelink reference signals for positioning. The information 504 corresponds to the information provided by the first WD 300A in S101 of Fig. 2.

In one or more examples, the network node 400, 600 determines resources for transmission of sidelink reference signals for positioning and sends an indication of the resources for transmission of sidelink reference signals for positioning 506 to the first WD 300A and/or the second WD 300B. In other words, the sidelink resource allocation node may determine one or more resource configurations (such as, a resource pre-configuration and/or a resource reservation) for transmission of sidelink reference signals for positioning associated with the at least one of the first WD 300A and the second WD 300B. In other words, the network node 400, 600 may determine, such as allocate, resources for transmission of sidelink reference signals for positioning via one or more of: a Physical Sidelink Control Channel (PSCCH), a PSSCH. This may be similar to S902 and/or to S907 performed by the radio network node 400 in Fig. 7.

The second WD 300B transmits, to the first WD 300B, the sidelink reference signal 508 for positioning. The sidelink reference signal 508 corresponds to the sidelink reference signal received by the first WD 300A in S105 of Fig. 2 and transmitted by the second WD 300B in S205 of Fig. 6.

In one or more examples, the first WD 300A determines whether a quality of the received sidelink reference signal for positioning meets a quality criterion 510. The first WD 300A may determine whether the quality of the received sidelink reference signal for positioning meets the quality criterion 510 based on a positioning measurement and/or combination of positioning measurements (such as based on RSRP, and/or LOS classifications). For example, the first WD 300A may determine that the received sidelink reference signal for positioning meets the quality criterion 510 when a positioning measurement is equal to or above a quality threshold. In one or more examples, the first WD 300A may determine that the received sidelink reference signal for positioning does not meet the quality criterion 510 when a positioning measurement is below the quality threshold. This corresponds to S107 performed by the first WD in Fig. 2.

The first WD 300A transmits, to the second WD 300B and/or to the network node 400, 600, positioning feedback information 512 indicative of the quality of the received sidelink reference signal 508 for positioning. For example, the positioning feedback information 512 can comprise a positive feedback, such as an ACK, when the received sidelink reference signal for positioning meets the quality criterion. For example, the positioning feedback information 512 can comprise a negative feedback, such as a NACK, when the received sidelink reference signal for positioning fails to meet the quality criterion. The positioning feedback information 512 corresponds to the positioning feedback information transmitted by the first WD 300A in S109 of Fig. 2 and the positioning feedback information received by the second WD in S207 of Fig. 6. In one or more examples, the positioning feedback information 512 comprises negative feedback, such as feedback information being indicative of the quality of the received reference signals for positioning not meeting a quality criterion. The second WD 300B may initiate a further transmission, such as a retransmission, of sidelink reference signal 514 for positioning in response to the positioning feedback information 512 comprising the negative feedback. In other words, the second WD 300B may perform a retransmission of sidelink reference signal 514 for positioning. The further transmission of sidelink reference signals 514 for positioning corresponds to the further transmission of sidelink reference signals for positioning initiated by the second WD 300B in S209 of Fig. 6 and received by the first WD 300A in S109 of Fig. 2.

Fig. 12 is a signaling diagram illustrating an example communication 700 between the first WD 300A, the second WD 300B, and the radio network node 400 according to this disclosure.

In one or more examples, the radio network node 400 transmits, to at least one of the first WD 300A and the second WD 300B, feedback configuration information 702 indicative of a configuration to be used for transmitting and/or receiving positioning feedback information. The feedback configuration information 504 corresponds to the feedback configuration information obtained by the first WD in S103 of Fig. 2 and is similar to the feedback configuration information transmitted from the second WD 300B to the first WD 300A in S203. The second WD 300B may receive the feedback configuration information from the radio network node 400 and may forward the information to the first WD 300A in S203.

In one or more examples, the first WD 300A transmits, to the second WD 300B and/or to the radio network node 400, information 704, indicative of the first WD’s capability to transmit the positioning feedback information. The information 704 corresponds to the information provided by the first WD 300A in S101 of Fig. 2 and received by the second WD 300B in S201 and by the radio network node 400 in S904 of Fig. 7.

In one or more examples, the second WD 300B transmits, to the radio network node 400, a request 706 for performing a transmission of sidelink reference signals for positioning with feedback.

In one or more examples, the radio network node 400 assigns, based on the request 706, resources 708 for transmission of the sidelink reference signal for positioning, such as in a set of resources, such as a slot, comprising resources for transmitting positioning feedback information. In one or more examples, the radio network node 400 transmits and/or provides, to the second WD 300B, information 710 indicative of the resources 708 for transmission of the sidelink reference signal 712 for positioning.

The second WD 300B transmits, to the first WD 300A, a sidelink reference signal 712 for positioning. The sidelink reference signal 712 for positioning may be transmitted in the indicated resources 708. The sidelink reference signal 712 for positioning corresponds to the sidelink reference signal for positioning transmitted by the second WD 300B in S205 of Fig. 6 and received by the first WD in S105 of Fig. 2.

In one or more examples, the first WD 300A determines 714 whether a quality of the received sidelink reference signal 712 for positioning meets a quality criterion. The first WD 300A may determine whether the quality of the received sidelink reference signal 712 for positioning meets the quality criterion based on a positioning measurement and/or combination of positioning measurements (such as based on RSRP, and/or LOS classifications). For example, the first WD 300A may determine that the received sidelink reference signal 712 for positioning meets the quality criterion 714 when a positioning measurement is equal to or above a quality threshold. In one or more examples, the first WD 300A may determine that the received sidelink reference signal 712 for positioning does not meet the quality criterion 714 when a positioning measurement is below the quality threshold. Determining 714 corresponds to S107 performed by the first WD 300A in Fig. 2.

The first WD 300A transmits, to the second WD 300B, positioning feedback information 716 indicative of the quality of the received sidelink reference signal 712 for positioning. For example, the positioning feedback information 716 can comprise positive feedback, such as an ACK, when the received sidelink reference signal 712 for positioning meets the quality criterion 714. For example, the positioning feedback information 716 can comprise negative feedback, such as a NACK, when the received sidelink reference signal 712 for positioning fails to meet the quality criterion 714. The positioning feedback information 716 corresponds to the positioning feedback information transmitted by the first WD in S109 of Fig. 2 and received by the second WD 300B in S207 of Fig. 6.

In one or more examples, the second WD 300B, upon the positioning feedback information comprising an indication that the quality of the received sidelink reference signals fails to meet the quality criterion, initiates a further transmission of sidelink reference signal for positioning. In other words, the second WD 300B may perform a retransmission of sidelink reference signals for positioning. In one or more example methods, the second WD 300B transmits, to the radio network node 400, a request 718 for resources for the further transmission of sidelink reference signal for positioning. The request 718 corresponds to the request transmitted by the second WD 300B in S209A of Fig. 6 and is similar to the positioning feedback information received by the radio network node 400 in S907 of Fig. 7.

The radio network node 400 may assign and resources for transmission of the further sidelink reference signal for positioning and may transmit, to the second WD 300B, a sidelink reference signal configuration 720, such as a second sidelink reference signal configuration, for further transmission of sidelink reference signal. The sidelink reference signal configuration 720 may be indicative of resources to be used for the further transmission, such as retransmission, of the sidelink reference signals for positioning. The configuration may be the same as the configuration of the previous transmission or may be different configuration (e.g., different bandwidth, different frequency allocation, etc.). The sidelink reference signal configuration 720 corresponds to the sidelink reference signal configuration received by the second WD 300B in S209B of Fig. 6 and to second sidelink reference signal configuration provided by the radio network node 400 in S909 of Fig. 7.

In one or more example methods, the second WD 300B may transmit, to the first WD 300B, the further sidelink reference signal 722 for positioning, such as according to the second sidelink reference signal configuration 720. The sidelink reference signal 722 corresponds to the sidelink reference signal transmitted by the second WD 300B in S209C of Fig. 6 and to sidelink reference signal received by the first WD 300A in S111 of Fig. 2.

Examples of methods and products (first WD, second WD and radio network node) according to the disclosure are set out in the following items:

Item 1 . A method performed in a first wireless device, WD, for enabling sidelink positioning, the method comprising: receiving (S105), from a second WD, a sidelink reference signal for positioning, and transmitting (S109), to the second WD, positioning feedback information indicative of a quality of the received sidelink reference signal for positioning.

Item 2. The method according to Item 1 , wherein the method comprises: determining (S107), based on the received sidelink reference signal, the quality of the received sidelink reference signal for positioning.

Item 3. The method according to Item 1 or 2, wherein the method comprises: obtaining (S103) feedback configuration information indicative of a configuration to be used for transmitting positioning feedback information.

Item 4. The method according to Item 3, wherein the feedback configuration information is indicative of one or more of: an availability of a positioning feedback mechanism, whether positioning feedback information is to be transmitted or not, resources for providing positioning feedback information, a positioning measurement type to be used for determining positioning feedback information, and one or more thresholds for transmitting positioning feedback information.

Item 5. The method according to any one of the previous Items, wherein the positioning feedback information is transmitted in a physical sidelink channel dedicated for transmission of positioning feedback information.

Item 6. The method according to Item 5, wherein the physical sidelink channel dedicated for transmission of positioning feedback information is associated to one or more WDs and/or one or more sidelink positioning resource occasion.

Item 7. The method according to any one of the Items 5 to 6, wherein the physical sidelink channel dedicated for transmission of positioning feedback information is allocated in at least one Orthogonal Frequency-Division Multiplexing, OFDM, symbol within a slot containing sidelink reference signals for positioning.

Item 8. The method according to any one of the Items 5 to 7, wherein the physical sidelink channel dedicated for transmission of positioning feedback information is allocated in every N slot(s) containing sidelink reference signals for positioning, in which N >= 1. Item 9. The method according to any one of the previous Items, wherein the method comprises: providing (S101), to a sidelink resource allocating node, information indicative of the first WD’s capability to transmit positioning feedback information.

Item 10. The method according to any one of the previous Items, wherein the positioning feedback information comprises one or more of: an acknowledgement, ACK, indicating that the quality of the received sidelink reference signal for positioning meets a quality criterion, a non-acknowledgement, NACK, indicating that the quality of the received sidelink reference signal for positioning fails to meet a quality criterion, an absolute value indicative of the quality of the received sidelink reference signal for positioning, and a relative value indicative of the quality of the received sidelink reference signal for positioning.

Item 11. The method according to any one of the previous Items, wherein the method comprises: upon the positioning feedback information being indicative of the quality of the received sidelink reference signal for positioning not meeting a quality criterion, receiving (S105), from the second WD, further sidelink reference signal for positioning.

Item 12. A method performed in a second wireless device, WD, for handling sidelink positioning of a first WD, the method comprising: transmitting (S205), to the first WD, a sidelink reference signal for positioning, and receiving (S207), from the first WD, positioning feedback information indicative of a quality of the sidelink reference signal for positioning received by the first WD.

Item 13. The method according to Item 12, wherein the method comprises: initiating (S209), based on the positioning feedback information, a further transmission of sidelink reference signal for positioning.

Item 14. The method according to Item 13, wherein initiating (S209) comprises: sending (S209A), to a sidelink resource allocating node, a request for resources for the further transmission of sidelink reference signal for positioning. Item 15. The method according to Item 13 or 14, wherein initiating (S209) comprises: transmitting (S209B), to the first WD, further sidelink reference signal for positioning.

Item 16. The method according to Item 15, wherein the further sidelink reference signals are transmitted in a preconfigured resource for further transmission of the sidelink reference signal for positioning, or in a resource for further transmission of the sidelink reference signal for positioning received from the resource allocating node in response to transmitting the request for resources for the further transmission of sidelink reference signal.

Item 17. The method according to any one of the Items 12 to 16, wherein the method comprises: transmitting (S203), to the first WD, feedback configuration information indicative of a configuration to be used for transmitting positioning feedback information.

Item 18. The method according to Item 17, wherein the feedback configuration information is indicative of one or more of: an availability of the feedback mechanism, whether positioning feedback information is to be transmitted or not, resources for providing positioning feedback information, a positioning measurement type to be used for determining positioning feedback information, and one or more thresholds for transmitting positioning feedback information.

Item 19. The method according to any one of the Items 12 to 18, wherein the positioning feedback information is received in a physical sidelink channel dedicated for transmission of positioning feedback information.

Item 20. The method according to any one of the Items 12 to 19, wherein the method comprises: receiving (S201 ), from the first WD, information indicative of the first WD’s capability to transmit positioning feedback information.

Item 21. The method according to any one of the Items 12 to 20, wherein the positioning feedback information comprises one or more of: an acknowledgement, ACK, indicating that the quality of the received sidelink reference signal for positioning meets a quality criterion, a non-acknowledgement, NACK, indicating that the quality of the received sidelink reference signal for positioning fails to meet a quality criterion, an absolute value indicative of the quality of the received sidelink reference signal for positioning, and a relative value indicative of the quality of the received sidelink reference signal for positioning.

Item 22. A method performed in a radio network node, for enabling sidelink positioning of a first WD via a second WD, wherein the method comprises: providing (S302), to at least one of the first WD and the second WD, resources for transmission of a sidelink reference signal for positioning, and receiving (S305), from the at least one of the first WD and the second WD, positioning feedback information indicative of a quality of the received sidelink reference signal for positioning.

Item 23. The method according to Item 22, wherein the positioning feedback information comprises a request for resources for a further transmission of a sidelink reference signal for positioning.

Item 24. The method according to Item 22 or 23, wherein the method comprises: providing (S309), to at least one of the first WD and the second WD, a resource configuration for a further transmission of sidelink reference signal for positioning.

Item 25. The method according to any one of the Items 22 to 24, wherein the method comprises: transmitting (S301 ), to at least one of the first WD and the second WD, feedback configuration information indicative of a configuration to be used for transmitting positioning feedback information.

Item 26. The method according to any one of the Items 22 to 25, wherein the method comprises: receiving (S304), from at least one of the first WD and the second WD, information indicative of the WD’s capability to transmit positioning feedback information.

Item 27. The method according to any one of the Items 22 to 26, wherein the method comprises: determining (S307) a resource configuration for further transmission of sidelink reference signal for positioning.

Item 28. The method according to Item 27, wherein the resource configuration is determined in response to receiving the positioning feedback information.

Item 29. A method performed in a radio network node, for enabling sidelink positioning of a first WD via a second WD, wherein the method comprises: providing (S309), to at least one of the first WD and the second WD, a resource configuration for a further transmission of sidelink reference signal for positioning upon a quality of a sidelink reference signal transmitted using a first resource configuration fails to meet a quality criterion.

Item 30. A first wireless device comprising memory circuitry, processor circuitry, and a wireless interface, wherein the first wireless device is configured to perform any of the methods according to any of Items 1-11.

Item 31. A second wireless device comprising memory circuitry, processor circuitry, and a wireless interface, wherein the second wireless device is configured to perform any of the methods according to any of Items 12-21.

Item 32. A radio network node comprising memory circuitry, processor circuitry, and a wireless interface, wherein the radio network node is configured to perform any of the methods according to any of Items 22-28.

The use of the terms “first”, “second”, “third” and “fourth”, “primary”, “secondary”, “tertiary” etc. does not imply any particular order, but are included to identify individual elements. Moreover, the use of the terms “first”, “second”, “third” and “fourth”, “primary”, “secondary”, “tertiary” etc. does not denote any order or importance, but rather the terms “first”, “second”, “third” and “fourth”, “primary”, “secondary”, “tertiary” etc. are used to distinguish one element from another. Note that the words “first”, “second”, “third” and “fourth”, “primary”, “secondary”, “tertiary” etc. are used here and elsewhere for labelling purposes only and are not intended to denote any specific spatial or temporal ordering. Furthermore, the labelling of a first element does not imply the presence of a second element and vice versa.

It may be appreciated that Figures comprise some circuitries or operations which are illustrated with a solid line and some circuitries, components, features, or operations which are illustrated with a dashed line. Circuitries or operations which are comprised in a solid line are circuitries, components, features, or operations which are comprised in the broadest example. Circuitries, components, features, or operations which are comprised in a dashed line are examples which may be comprised in, or a part of, or are further circuitries, components, features, or operations which may be taken in addition to circuitries, components, features, or operations of the solid line examples. It should be appreciated that these operations need not be performed in order presented. Furthermore, it should be appreciated that not all of the operations need to be performed. The example operations may be performed in any order and in any combination. It should be appreciated that these operations need not be performed in order presented. Circuitries, components, features, or operations which are comprised in a dashed line may be considered optional.

Other operations that are not described herein can be incorporated in the example operations. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations.

Certain features discussed above as separate implementations can also be implemented in combination as a single implementation. Conversely, features described as a single implementation can also be implemented in multiple implementations separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations, one or more features from a Itemed combination can, in some cases, be excised from the combination, and the combination may be Itemed as any sub-combination or variation of any sub-combination

It is to be noted that the word "comprising" does not necessarily exclude the presence of other elements or steps than those listed.

It is to be noted that the words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements.

It should further be noted that any reference signs do not limit the scope of the claims, that the examples may be implemented at least in part by means of both hardware and software, and that several "means", "units" or "devices" may be represented by the same item of hardware.

Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than or equal to 10% of, within less than or equal to 5% of, within less than or equal to 1 % of, within less than or equal to 0.1% of, and within less than or equal to 0.01 % of the stated amount. If the stated amount is 0 (e.g., none, having no), the above recited ranges can be specific ranges, and not within a particular % of the value. For example, within less than or equal to 10 wt./vol. % of, within less than or equal to 5 wt./vol. % of, within less than or equal to 1 wt./vol. % of, within less than or equal to 0.1 wt./vol. % of, and within less than or equal to 0.01 wt./vol. % of the stated amount. The various example methods, devices, nodes, and systems described herein are described in the general context of method steps or processes, which may be implemented in one aspect by a computer program product, embodied in a computer-readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and nonremovable storage devices including, but not limited to, Read Only Memory (ROM), Random Access Memory (RAM), compact discs (CDs), digital versatile discs (DVD), etc. Generally, program circuitries may include routines, programs, objects, components, data structures, etc. that perform specified tasks or implement specific abstract data types. Computer-executable instructions, associated data structures, and program circuitries represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

Although features have been shown and described, it will be understood that they are not intended to limit the claimed disclosure, and it will be made obvious to those skilled in the art that various changes and modifications may be made without departing from the scope of the claimed disclosure. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. The claimed disclosure is intended to cover all alternatives, modifications, and equivalents.

Claims

1 . A method performed in a first wireless device, WD, for enabling sidelink positioning, the method comprising: receiving (S105), from a second WD, a sidelink reference signal for positioning, and transmitting (S109), to the second WD, positioning feedback information indicative of a quality of the received sidelink reference signal for positioning.

2. The method according to claim 1 , wherein the method comprises: determining (S107), based on the received sidelink reference signal, the quality of the received sidelink reference signal for positioning.

3. The method according to claim 1 or 2, wherein the method comprises: obtaining (S103) feedback configuration information indicative of a configuration to be used for transmitting positioning feedback information.

4. The method according to claim 3, wherein the feedback configuration information is indicative of one or more of: an availability of a positioning feedback mechanism, whether positioning feedback information is to be transmitted or not, resources for providing positioning feedback information, a positioning measurement type to be used for determining positioning feedback information, and one or more thresholds for transmitting positioning feedback information.

5. The method according to any one of the previous claims, wherein the positioning feedback information is transmitted in a physical sidelink channel dedicated for transmission of positioning feedback information.

6. The method according to claim 5, wherein the physical sidelink channel dedicated for transmission of positioning feedback information is associated to one or more WDs and/or one or more sidelink positioning resource occasion.

7. The method according to any one of the claims 5 to 6, wherein the physical sidelink channel dedicated for transmission of positioning feedback information is allocated in at least one Orthogonal Frequency-Division Multiplexing, OFDM, symbol within a slot containing sidelink reference signals for positioning.

8. The method according to any one of the claims 5 to 7, wherein the physical sidelink channel dedicated for transmission of positioning feedback information is allocated in every N slot(s) containing sidelink reference signals for positioning, in which N >= 1.

9. The method according to any one of the previous claims, wherein the method comprises: providing (S101), to a sidelink resource allocating node, information indicative of the first WD’s capability to transmit positioning feedback information.

10. The method according to any one of the previous claims, wherein the positioning feedback information comprises one or more of: an acknowledgement, ACK, indicating that the quality of the received sidelink reference signal for positioning meets a quality criterion, a non-acknowledgement, NACK, indicating that the quality of the received sidelink reference signal for positioning fails to meet a quality criterion, an absolute value indicative of the quality of the received sidelink reference signal for positioning, and a relative value indicative of the quality of the received sidelink reference signal for positioning.

11. The method according to any one of the previous claims, wherein the method comprises: upon the positioning feedback information being indicative of the quality of the received sidelink reference signal for positioning not meeting a quality criterion, receiving (S105), from the second WD, further sidelink reference signal for positioning.

12. A method performed in a second wireless device, WD, for handling sidelink positioning of a first WD, the method comprising: transmitting (S205), to the first WD, a sidelink reference signal for positioning, and receiving (S207), from the first WD, positioning feedback information indicative of a quality of the sidelink reference signal for positioning received by the first WD.

13. The method according to claim 12, wherein the method comprises: initiating (S209), based on the positioning feedback information, a further transmission of sidelink reference signal for positioning.

14. The method according to claim 13, wherein initiating (S209) comprises: sending (S209A), to a sidelink resource allocating node, a request for resources for the further transmission of sidelink reference signal for positioning.

15. The method according to claim 13 or 14, wherein initiating (S209) comprises: transmitting (S209B), to the first WD, further sidelink reference signal for positioning.

16. The method according to claim 15, wherein the further sidelink reference signals are transmitted in a preconfigured resource for further transmission of the sidelink reference signal for positioning, or in a resource for further transmission of the sidelink reference signal for positioning received from the resource allocating node in response to transmitting the request for resources for the further transmission of sidelink reference signal.

17. The method according to any one of the claims 12 to 16, wherein the method comprises: transmitting (S203), to the first WD, feedback configuration information indicative of a configuration to be used for transmitting positioning feedback information.

18. The method according to claim 17, wherein the feedback configuration information is indicative of one or more of: an availability of the feedback mechanism, whether positioning feedback information is to be transmitted or not, resources for providing positioning feedback information, a positioning measurement type to be used for determining positioning feedback information, and one or more thresholds for transmitting positioning feedback information.

19. The method according to any one of the claims 12 to 18, wherein the positioning feedback information is received in a physical sidelink channel dedicated for transmission of positioning feedback information.

20. The method according to any one of the claims 12 to 19, wherein the method comprises: receiving (S201 ), from the first WD, information indicative of the first WD’s capability to transmit positioning feedback information.

21. The method according to any one of the claims 12 to 20, wherein the positioning feedback information comprises one or more of: an acknowledgement, ACK, indicating that the quality of the received sidelink reference signal for positioning meets a quality criterion, a non-acknowledgement, NACK, indicating that the quality of the received sidelink reference signal for positioning fails to meet a quality criterion, an absolute value indicative of the quality of the received sidelink reference signal for positioning, and a relative value indicative of the quality of the received sidelink reference signal for positioning.

22. A method performed in a radio network node, for enabling sidelink positioning of a first WD via a second WD, wherein the method comprises: providing (S302), to at least one of the first WD and the second WD, resources for transmission of a sidelink reference signal for positioning, and receiving (S305), from the at least one of the first WD and the second WD, positioning feedback information indicative of a quality of the received sidelink reference signal for positioning.

23. The method according to claim 22, wherein the positioning feedback information comprises a request for resources for a further transmission of a sidelink reference signal for positioning.

24. The method according to claim 22 or 23, wherein the method comprises: providing (S309), to at least one of the first WD and the second WD, a resource configuration for a further transmission of sidelink reference signal for positioning.

25. The method according to any one of the claims 22 to 24, wherein the method comprises: transmitting (S301 ), to at least one of the first WD and the second WD, feedback configuration information indicative of a configuration to be used for transmitting positioning feedback information.

26. The method according to any one of the claims 22 to 25, wherein the method comprises: receiving (S304), from at least one of the first WD and the second WD, information indicative of the WD’s capability to transmit positioning feedback information.

27. The method according to any one of the claims 22 to 26, wherein the method comprises: determining (S307) a resource configuration for further transmission of sidelink reference signal for positioning.

28. The method according to claim 27, wherein the resource configuration is determined in response to receiving the positioning feedback information.

29. A first wireless device comprising memory circuitry, processor circuitry, and a wireless interface, wherein the first wireless device is configured to perform any of the methods according to any of claims 1-11 .

30. A second wireless device comprising memory circuitry, processor circuitry, and a wireless interface, wherein the second wireless device is configured to perform any of the methods according to any of claims 12-21.

31. A radio network node comprising memory circuitry, processor circuitry, and a wireless interface, wherein the radio network node is configured to perform any of the methods according to any of claims 22-28.