Methods for enabling positioning of a wireless device, related nodes and a related wireless device

Abstract

A method is disclosed, performed by a retro-reflective node, for enabling positioning of a wireless device (WD). The method comprises receiving, from the WD, a first signal using a first plurality of antennas of the antenna array in a first retro-reflective configuration. The method comprises retransmitting the signal using the first plurality of antennas of the antenna array in the first retro-reflective configuration. The method comprises reconfiguring the retro-reflective configuration of the antenna array from the first retro-reflective configuration to a second retro-reflective configuration. The method comprises receiving, from the WD, a second signal using a second plurality of antennas of the antenna array in the second retro-reflective configuration. The method comprises retransmitting the signal using the plurality of antennas of the antenna array in the second retro-reflective configuration.

Description

[0001] METHODS FOR ENABLING POSITIONING OF A WIRELESS DEVICE, RELATED NODES

[0002] AND A RELATED WIRELESS DEVICE

[0003] The present disclosure pertains to the field of wireless communications. The present disclosure relates to methods for enabling positioning of a wireless device, a related retro-reflective node, a related wireless device, and a related radio network node.

[0004] BACKGROUND

[0005] In positioning systems, anchor nodes are of great value for the overall performance. Anchor nodes are a part of the positioning infrastructure and can take on many different forms. Examples of operations of anchor nodes are nodes that transmit pilots, to which a wireless device (WD) responds. Based on the response a Round Trip Time (RTT) may be computed by the anchor node. The RTT gives a distance to the WD from a known position of the anchor node, which is important for positioning of the WD. Another type of operation that an anchor node can carry out is to reflect / respond to a signal transmitted by the WD. Also in this case, the distance to the anchor node can be calculated based on RTT. Further, if the WD is equipped with multiple antennas, then the WD can estimate a direction towards the anchor. However, in a typical situation where the WD has limited spatial resolution, for example when the WD is a single antenna WD, the angle towards the anchor node cannot be computed. For such a WD, the only viable way to obtain angular information appears to be that the anchor is equipped with multiple antennas and estimates the spatial direction toward the WD. In a later stage, the anchor node may forward the estimated angle. This approach however requires high complexity at the anchor node, as it must scan for an incoming signal, perform baseband operations to calculate the angle, and then forward the estimate.

[0006] SUMMARY

[0007] Accordingly, there is a need for devices and methods for enabling positioning of a WD, which may mitigate, alleviate, or address the shortcomings existing and may provide positioning solution requiring a lower complexity at the anchor node.

[0008] A method is disclosed, performed by a retro-reflective node, such as a node having an antenna array with an adaptable retro-reflective configuration, for enabling positioning of a WD. The method comprises receiving, from the WD, a first signal using a first plurality of antennas of the antenna array in a first retro-reflective configuration. The method comprises retransmitting the signal using the first plurality of antennas of the antenna array in the first retro-reflective configuration. The method comprises reconfiguring the retro-reflective configuration of the antenna array from the first retro-reflective configuration to a second retro-reflective configuration. The method comprises receiving, from the WD, a second signal using a second plurality of antennas of the antenna array in the second retro-reflective configuration. The method comprises retransmitting the signal using the plurality of antennas of the antenna array in the second retro-reflective configuration.

[0009] Further, a retro-reflective node, such as a node having an antenna array with an adaptable retro-reflective configuration, is provided, the node comprising memory circuitry, processor circuitry, and a wireless interface, wherein the node is configured to perform any of the methods disclosed herein relating to the node having an antenna array with an adaptable retro-reflective configuration.

[0010] It is an advantage of the present disclosure that the retro-reflective node can use a substantially passive hardware architecture comprising a set of switches to switch its antenna array into a plurality of retro-reflective configurations for generating a plurality of spatially offset retro- reflected signals that the WD can use to estimate its relative angle to the retro-reflective node. The retro-reflected signal is reflected toward the origin of the received signal. For all retro- reflective configurations, the relative phase as observed by the WD, associated with the different configurations is directly related to the spatial direction of the WD in relation to the retro-reflective node. This reduces the complexity of the retro-reflective node required for enabling the positioning of the WD. Switching the retro-reflective configuration to reflect signals from the WD with reflective beams having offset center of origins generates a phase shift that relates to the angle to the WD from the retro reflective node. This allows a single antenna transmitter WDs to compute its spatial angle towards the retro-reflective node. Thereby, an overall complexity of the wireless communication network may be reduced.

[0011] A method is disclosed, performed by a WD, for positioning of the WD. The method comprises transmitting, to a retro-reflective node, such as a node having an antenna array with an adaptable retro-reflective configuration, a signal. The method comprises receiving, from the node having an antenna array with an adaptable retro-reflective configuration, a first reflected signal of the transmitted signal. The method comprises receiving, from the retro-reflective node, a second reflected signal of the transmitted signal. The method comprises determining, based on the first reflected signal and the second reflected signal a first measurement value indicative of a spatial direction of the wireless device relative to the node.

[0012] Further, a wireless device is provided, the wireless device comprising memory circuitry, processor circuitry, and a wireless interface, wherein the wireless device is configured to perform any of the methods disclosed herein relating to the wireless device. It is an advantage of the present disclosure that the WD based on a plurality of spatially offset reflections of a signal transmitted by the WD can estimate its relative angle in relation to the retro-reflective node. Since the retro-reflective node uses a plurality of retro-reflective configurations and the signal is reflected toward the origin of the signal transmitted from the WD. For all retro-reflective configurations, the relative phase associated with the different configurations is directly related to the spatial direction of the WD in relation to the retro- reflective node. The retro-reflective node can use a substantially passive hardware architecture to switch its antenna array into the plurality of retro-reflective configurations for generating a plurality of spatially offset retro-reflected signals. This reduces the complexity of the retro- reflective node required for enabling the positioning of the WD. Switching the retro-reflective configuration to reflect signals from the WD with offset reflective beams, allows the WD, such as a single antenna transmitter WD without any beam forming capability, to compute its spatial angle towards the retro-reflective node. By determining its spatial angle towards a plurality of retro-reflective nodes, the WD may determine its own position. By determining its spatial angle in relation to at least two retro-reflective nodes, the WD can determine its position in a two- dimensional space and / or a three-dimensional space. The claimed solution thus enables a WD based positioning with reduce complexity, since the WD simply has to measure a phase shift of the reflected signals and computes the spatial angle based on the phase shift. Since the position of the retro-reflective nodes are known, the WD can compute its position by determining its spatial angle towards a plurality of retro-reflective nodes. This solution thus reduces the complexity of the WD and the retro-reflective node required for estimating the position of the WD, and allows a single antenna transmitter WD without any beam forming capability to estimate its position in a simple manner. Thereby, an overall complexity of the wireless communication network may be reduced.

[0013] A method is disclosed, performed in a radio network node, for enabling positioning of a WD. The method comprises sending, to the WD, a signal configuring the WD to use a retro-reflective node to determine a position of the WD.

[0014] Further, a radio network node is provided, the 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 disclosed herein relating to the radio network node.

[0015] It is an advantage of the present disclosure that the radio network node can configure the WD to use a retro-reflective node to determine its angle towards the retro-reflective node, which allows the use of less complex retro-reflective nodes for positioning of WDs. Thereby, the overall complexity of the wireless communication network may be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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:

[0017] Fig. 1 is a diagram illustrating an example wireless communication system comprising an example radio network node, an example wireless device, and an example retro-reflective node according to this disclosure,

[0018] Fig. 2A-2C are diagrams illustrating example retro-reflective configurations of the retro-reflective node according to this disclosure,

[0019] Fig. 3 is a flow-chart illustrating an example method, performed in a retro-reflective node of a wireless communication system, for enabling positioning of a wireless device according to this disclosure,

[0020] Fig. 4 is a flow-chart illustrating an example method, performed in a wireless device of a wireless communication system, for positioning of the wireless device according to this disclosure,

[0021] Fig. 5 is a flow-chart illustrating an example method, performed in a radio network node of a wireless communication system, for enabling positioning of a wireless device according to this disclosure,

[0022] Fig. 6 is a block diagram illustrating an example retro-reflective node according to this disclosure,

[0023] Fig. 7 is a block diagram illustrating an example wireless device according to this disclosure, and

[0024] Fig. 8 is a block diagram illustrating an example radio network node according to this disclosure.

[0025] DETAILED DESCRIPTION

[0026] 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.

[0027] 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.

[0028] Fig. 1 is a diagram illustrating an example wireless communication system 1 comprising an example radio network node 400, example wireless device 300and an example retro-reflective node 500.

[0029] 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. The wireless communication system 1 may comprise one or more wireless device 300and one or more radio network nodes 400.

[0030] A radio network node disclosed herein refers to a radio access network node operating in the radio access network (RAN), such as one or more of: a base station, an evolved Node B, an eNB, a gNB in NR and an access point. In one or more examples, the RAN node is a functional unit which may be distributed in several physical units.

[0031] A wireless device may refer to one or more of: a mobile device and a user equipment (UE).

[0032] The wireless device 300 may be configured to communicate with the network node 400 via a wireless link (or radio access link) 10 .

[0033] The retro-reflective node 500 may refer to a node an antenna array with an adaptable retro- reflective configuration according to this disclosure. The retro-reflective node may be an anchor node having a known position and / or a coverage enhancing device (CED). The wireless communication system 1 of Fig. 1 may comprise one or more retro-reflective nodes 500. The retro-reflective node 500 may be configured to reflect and / or redirect signals between other components of the wireless communication system 1 , such as the wireless device 300 and the network node 400.

[0034] In the example shown in Fig. 1 , a first wireless device 300 may be configured to communicate with the radio network node 400 directly via a first wireless link 10 or via a second wireless link (or radio access link) 10A, 10B, in which the signals between the first wireless device 300 and the network node 400 are redirected by the retro-reflective node 500. The retro-reflective node 500 can be configured in one or more retro-reflective configuration(s) in which a signal transmitted by the WD 300 on the second wireless link 10A to the retro-reflective node 500 is reflected in the same direction back to the WD 300.

[0035] In one or more examples, the WD 300 may be a single antenna WD. A single antenna WD may only be able to provide an angular position relative to retro-reflective node, such as to the retro- reflective antenna array.

[0036] The current disclosure relates to methods for enabling positioning of a WD, such as for providing directional estimates, such as to provide estimates for one or more of elevation and azimuth for a spatial direction between a WD and a node having an antenna array with an adaptable retro-reflective configuration, such as an anchor node. The node having an antenna array with an adaptable retro-reflective configuration will hereinafter be referred to as a retro- reflective node, such as an adaptable retro-reflective node.

[0037] In one or more examples, the direction to the WD from the adaptable retro-reflective node can be represented as a tuple of angles <p, 0, where represents azimuth, such as an azimuth angle, and 0 represents elevation, such as an elevation angle. The angles <p, 0 are measured at a reference point of the retro-reflective node. In one or more example methods, the WD is located in a far field from the retro-reflective node. Using standard conventions, these can be represented, by a one-to-one mapping, as a pair of directional cosines using the following formulas: kx= sin(0) sin( ), ky= sin(0) cos( )

[0038] Thus, if the WD can be made aware of kxand / or ky, the direction of the WD towards the retro- reflective node can be estimated by the WD. The parameters kxand / or kymay be unknown to the retro-reflective node.

[0039] In one or more examples, the retro-reflective node, such as the adaptable retro-reflective node, comprises an antenna array, such as a uniform rectangular array (URA) having equally many antenna elements, such as M antenna elements, in both a horizontal dimension and a vertical dimension. In one or more examples, the number M is an odd number. The solution disclosed herein may be applicable to any retro-reflective antenna array having a shape with “pointreflection” symmetry with regards to a geometrical center point, such as an origin point, r0, which means that if the antenna array has an antenna element at rn, then it also has a corresponding antenna element at —(rn— r0), such as an associated symmetric element. According to one or more example methods, if some element is not reflecting, such as when it is inactive, then this antenna element is not required to have an associated symmetric element. The origin point r0of the antenna array does not need to coincide with an antenna element. There may be one such origin point for each retro-reflective configuration, such as three origin points comprising r0(1)for the first retro-reflective configuration, r2)for the second retro- reflective configuration, and r3)for the third retro-reflective configuration. The solution disclosed herein may be applied to any antenna configurations achieving the above-mentioned effect relating to point-reflection symmetry with regards to the center point, such as any cluster of antennas capable of generating retro-reflections with different configurations that give raise to a deterministic phase shift. In one or more examples, the solution disclosed herein applies to an adaptable retro-reflective node having an even numberM antenna elements, a linear antenna array (LRA), or an URA with unequal number of antennas in the vertical and horizontal directions.

[0040] According to the current disclosure, the antenna array of the adaptable retro-reflective node can be configured in a plurality of retro reflective configurations, such as modes, for providing signals to the WD indicative of one or more of and 0.

[0041] In one or more examples, the antenna array of the adaptable retro-reflective node is an amended version of a Van Atta array. A Van Atta array is an antenna array from which a received signal is reflected in the same direction as it arrived from. In a Van Atta array pairs of antennas, such as antenna elements, of the antenna array may be connected using a wiring length for connecting the respective antenna pairs corresponding to a factor, such as an integer multiple, of a wavelength ( ) of the signal. The wiring shown in Figs. 2A-2C is only for illustrative purposes, and the antenna elements may be connected internally in the retro-reflective node using for example cables and / or circuit boards. Other methods know by a person skilled in the art may also be used for connecting the antenna elements. Due to the wiring length between the connected antenna elements being a multiple of the wavelength, the phase of a signal entering a first antenna element of the antenna pair is the same as the phase of a signal leaving a second antenna element of the antenna pair. According to the current disclosure, the antenna array can be switched, for example by a set of switches, in the plurality of modes, such as retro- reflective configurations. Three example modes, such as retro-reflective configurations are described in relation to Figs. 2A-2C. Each retro reflective configuration may comprise a respective subset of active antenna elements and a respective subset of non-active antenna elements. An active antenna element can herein be seen as a signal received by the antenna element being relayed by a different antenna element paired with the receiving antenna element. A non-active antenna element can herein be seen as a signal received by a of the non-active antenna element not being relayed by the antenna array. In Figs. 2A-2C, an active antenna element is indicated as a white circle, while a non-active antenna element is indicated as a black circle. A signal being relayed or reflected can herein be seen as the signal being retransmitted without being digitally processed by the retro-reflective node.

[0042] Fig. 2A describes a first mode, such as a first retro-reflective configuration according to the current disclosure. In the first mode, the antenna array may operate essentially according to a conventional Van Atta array.

[0043] For example, a signal arriving at an antenna element (m,ri), 1 < m,n < M, where m indexes the vertical direction and n the horizontal direction of the antenna element in the antenna array can herein be denoted as smjl. A traditional Van Atta array would be implemented so that the signal is re-transmitted from antenna element (M + 1 - m, M + l — n).

[0044] According to one or more examples of the current disclosure, the first mode is configured according to Equations (1) and (2) below:

[0045] Fig. 2A illustrates the example first retro-reflective configuration for an antenna array with M=5. In this case, one active antenna element of the antenna array is paired, such as connected to, a second antenna element arranged at an equal distance from a center point of the antenna array, such as a common center point of the set of active antenna elements, as the first antenna element. In other words, a signal received at antenna element m=1 , n=1 , will according to Eq. 1 , be relayed from antenna element m=5, n=5, which are paired, such as connected via wiring. A signal received on an antenna element (m, 3) or (3, n), will however not be relayed in accordance with Eq. 2. The length of the wiring may be chosen so that they correspond to an integer multiple of the wavelength of the signal. The length of the wiring of different antenna element pairs may not have to be the same but may all correspond to a respective integer multiple of the wavelength of the signal. A common offset length may be added to the length of the wiring of different antenna element pairs. In one or more example methods, a radio channel between the WD and antenna element (m,n) can be represented as: where A is a real value representative of a path loss of the radio channel, and <pDLis a phase value of the downlink (DL) absorbing the distance between the WD and a reference point at the antenna array as well as the transmit filter at the WD. Correspondingly, the channel from antenna element (m,ri) to the WD becomes: where the phase value <pULof the uplink (UL) differs from <pDLdue to the receive filter at the WD.

[0046] A first reflected signal n at the WD for the first retro-reflective configuration, can thus be described as:

[0047] According to one or more example methods, the first reflected signal may be reference signal having a reference phase. The reference signal, such as the reference phase, may be used by the WD to determine estimates for one or more of elevation and azimuth for a spatial direction between the WD and the retro-reflective node.

[0048] Fig. 2B describes an example second mode, such as a second retro-reflective configuration, according to the current disclosure for an example antenna array having M = 5. In the example second mode, the retro-reflective configuration is shifted in a horizontal direction in relation to the first retro-reflective configuration. In the example second mode, the antenna array is configured according to Equations (4) and (5) below:

[0049] It follows that an example second reflected signal r2 to the WD using the second mode at the retro-reflective node, becomes:

[0050] By shifting the retro-reflective configuration in the horizontal direction, a geometrical center point of the second plurality of antennas, such as the second plurality of active antenna elements, is offset from a geometrical center point of the first plurality of antennas, such as the plurality of first active antennas. Fig. 2C describes an example third mode, such as a third retro-reflective configuration, according to the current disclosure for an example antenna array having M = 5. In the example third mode, the retro-reflective configuration is shifted in a vertical direction in relation to the first retro-reflective configuration. In the example third mode, the antenna array is configured according to Equations (7) and (8) below: is not retransmitted

[0051] It follows that an example third reflected signal r2to the WD using the third mode at the retro- reflective node, becomes:

[0052] By shifting the retro-reflective configuration in the vertical direction, a geometrical center point of the third plurality of antennas, such as the third plurality of active antenna elements, is offset from a geometrical center point of the first plurality of antennas, such as the plurality of first active antennas, and / or the second plurality of antennas, such as of the plurality of second active antennas.

[0053] In one or more example methods, corresponding modes may be applied to a linear Van Atta array. However, in this case only two estimates may be made, such as either azimuth or elevation, since the active antenna elements in the linear antenna array can only be shifted in one single direction.

[0054] In one or more example methods, a WD transmitting the signal receives the three reflected signals ri,r2>r3 from the retro-reflective node. Based on the received reflected signals the WD may determine the pair of directional cosines kxand kyaccording to the following equations (10) and (11 ):

[0055] In one or more example methods, one of the reflected signals is used as a reference signal, in relation to which a vertical or horizontal shift for the two other reflected signals is determined. In the example shown in equations 10 and 11 , the first reflected signal r is used as the reference signal, in relation to which a vertical or horizontal shift for the second reflected signal r2and the third reflected signal r3is determined.

[0056] As the WD and the retro-reflective node are not synchronized, the WD may not know what parts of the received reflected signal that correspond to the three parts ri, r2>r3> respectively. In one or more example methods, one of the reflected signals may be indicated as being the reference signal. In one or more example methods, one of the modes, such as the retro-reflective configuration used for reflecting the reference signal, may be allocated for a longer time than the other modes. For example, in the examples described above where the first reflected signal is the reference signal, more time may be allocated to mode 1 , such as to the first retro- reflective configuration. Thus, the WD may receive three different reflected signals, where one signal may last for a longer duration than the other two. Thereby, the WD can be made aware of which signal that corresponds to the reference signal.

[0057] In one or more example methods, a pattern may be encoded into the reflected signals by the retro-reflective node. This may for example be done by introducing a fourth mode, such as a fourth retro-reflective configuration where the antenna array is not reflecting anything. In other words, in the fourth mode all antenna elements of the antenna array may be non-active. The reference mode, such as for example the first mode, and the fourth mode may be applied interchangeably according to a pre-determined pattern, in order to encode a pattern into the signal. In one or more example methods, the pattern may be indicative of an identity of the retro-reflective node or may be indicative of which one of the signals is the reference signal. In one or more example methods, the pattern may be encoded by switching among the already proposed three modes, such as switching between the example modes 1 , 2, and 3.

[0058] In one or more example methods, the reference signal may be indicated in an activation signal and / or synchronization signal. In one or more example methods, the order of the mode transmitting the reference signal may be indicated. For example, the retro-reflective mode may indicate that the reference signal will be transmitted as one of the initial signal, the middle signal, and / or the last signal in the sequence of reflected signals.

[0059] To implement the adaptable retro-reflective configuration according to the disclosure, being configurable in three modes, a first antenna element of the antenna array can be connected to a switch having three pins, wherein each pin of the switch is connected to a respective second antenna element. Thereby, for each antenna element being connected to a switch, three different pairs of antenna elements can be created by switching the switch between the pins. In other words, each pin corresponds to a respective retro-reflective configuration. If we for example take antenna element 1 ,1 of Figs. 2A-2C as an example, in the example mode 1 the switch of the antenna element 1 ,1 is switched so that the antenna element 1 ,1 is connected to antenna element 5,5 of the M=5 antenna array. In example mode 2, the switch of antenna element 1 ,1 may be switched so that the antenna element 1 ,1 is connected to antenna element 5,4 of the M=5 antenna array. In example mode 3, the switch of antenna element 1 ,1 may be switched so that the antenna element 1 ,1 is connected to antenna element 4,5 of the M=5 antenna array. However, other patterns, such as antenna pairs, may also be used for the different modes, as long as they provide a lateral and / or vertical offset of the geometrical center point between the modes.

[0060] For the antenna array shown in Figs. 2A-2C, the antenna array is made for M = 5. Since the retro-reflective configuration requires antenna element pairs, only 24 antenna elements out of the 25 available antenna elements are used for the retro-reflective configurations. In this example, antenna element 3,3 is not used. Each of the 24 antenna elements used for the retro reflective configuration may be connected to a respective switch having three pins. All switches may be configured to the same mode, such as modes 1 ,2,3. By switching all switches to position 1 , the antenna array may be configured into the retro-reflective configuration according to mode 1 , etc.

[0061] Fig. 3 shows a flow diagram of an example method 100, performed by a retro-reflective node, such as a node having an antenna array with an adaptable retro-reflective configuration, such as a Van Atta array, according to the disclosure, for enabling positioning of a WD. The antenna array having an adaptable retro-reflective configuration can herein be seen as having an adaptable antenna array configuration. The retro-reflective node is a node having an antenna array with an adaptable retro-reflective configuration, such as the retro-reflective node disclosed herein, such as the retro-reflective node 500 of Fig. 1 , and Fig. 6. The adaptable retro-reflective configuration may be an adaptable retro-reflective antenna array configuration.

[0062] The method 100 comprises receiving S102, from the WD, a first signal using a first plurality of antennas of the antenna array in a first retro-reflective configuration. In one or more example methods, the first plurality of antennas is a reference subset of antennas of the antenna array. Receiving S102 corresponds to transmitting S202 performed in method 200 of Fig. 4.

[0063] In one or more example methods, the method comprises transmitting S103, to the WD, a signal indicative of the transmission of the signal using the first plurality of antennas of the antenna array in the first retro-reflective configuration. The signal indictive of the transmission of the signal using the first plurality of antennas of the antenna array in the first retro-reflective configuration may comprise information being indicative of the first signal being the reference signal. In one or more example methods, the information being indicative of the first signal being the reference signal can be encoded into the signal by the retro-reflective node. The encoding of the information into the signal may comprise switching the retro-reflective configuration between the first retro-reflective configuration and a fourth retro-reflective configuration, such as a non-reflective configuration. The reference retro-reflective configuration, such as for example the first retro-reflective configuration, and the fourth retro-reflective configuration may be applied interchangeably according to a pre-determined pattern, to encode a pattern into the signal. In one or more example methods, the pattern may be indicative of an identity of the retro-reflective node or may be indicative of which one of the reflected signals is the reference signal. Transmitting S103 corresponds to receiving S203 performed in method 200 of Fig. 4.

[0064] The method 100 comprises retransmitting S104 the signal, such as a first signal, using the first plurality of antennas of the antenna array in the first retro-reflective configuration. In other words, the method 100 may comprise retransmitting S104 the signal, such as a first signal, to the WD using the first plurality of antennas of the antenna array in the first retro-reflective configuration, such as retro-reflecting the first signal toward the origin of the received signal, e.g., being the wireless device. In one or more example methods, retransmitting S104 the signal using the first plurality of antennas, such as antenna elements, of the antenna array in the first retro-reflective configuration comprises activating the first plurality of antennas for a longer duration than activating a second plurality of antennas for retransmitting S108 the signal using the plurality of antennas of the antenna array in the second retro-reflective configuration. Retransmitting S104 corresponds to receiving S204 performed in method 200 of Fig. 4.

[0065] The method 100 comprises reconfiguring S105 the retro-reflective configuration of the antenna array from the first retro-reflective configuration to a second retro-reflective configuration. In one or more example methods, a geometrical center point of the plurality of antennas in the second retro-reflective configuration is offset from a geometrical center point of the plurality of antennas of the first retro-reflective configuration. The geometrical center point of the plurality of antennas being offset can herein be seen as the center of the beam origin of a beam using the retro- reflective configuration being offset. In one or more example methods, the first plurality antennas and the second plurality of antennas are symmetrically spaced around their respective geometrical center point. The geometrical center point of the second plurality of antennas may be offset from the geometrical center point of the first plurality of antennas in one or more of a vertical direction and a horizontal direction of the antenna array. The plurality of antennas being active in each of the retro-reflective configurations, such as in the first, second and third retro- reflective configurations, are split in pairs wherein the antenna elements in each pair are arranged at the same distance from the center point. The method 100 comprises receiving S106, from the WD, a second signal using a second plurality of antennas of the antenna array in the second retro-reflective configuration. Receiving S106 corresponds to transmitting S202 performed in method 200 of Fig. 4.

[0066] The method 100 comprises retransmitting S108 the signal, such as a second signal, using the plurality of antennas of the antenna array in the second retro-reflective configuration. In other words, the method 100 may comprise retransmitting S108 the signal, such as a second signal, to the WD using the second plurality of antennas of the antenna array in the second retro- reflective configuration, such as retro-reflecting the second signal toward the origin of the received signal, e.g., being the wireless device. The beam origin of the relayed second signal is offset from the beam origin of the first relayed signal. In one or more example methods, retransmitting S108 the second signal using the second plurality of antennas, such as antenna elements, of the antenna array in the second retro-reflective configuration comprises activating the second plurality of antennas for a shorter duration than activating the first plurality of antennas for retransmitting S104 the first signal using the plurality of antennas of the antenna array in the first retro-reflective configuration.

[0067] In one or more example methods, the method comprises reconfiguring S109 the retro-reflective configuration of the antenna array from the second retro-reflective configuration to a third retro- reflective configuration. In one or more example methods, the geometrical center point of the plurality of antennas in the third retro-reflective configuration is offset from a geometrical center point of the plurality of antennas of the first retro-reflective configuration and from a geometrical center point of the plurality of antennas of the second retro-reflective configuration. In one or more example methods, if the second retro-reflective configuration is offset in a vertical direction, the third retro-reflective retro configuration may be offset in a horizontal direction. In one or more example methods, if the second retro-reflective configuration is offset in a horizontal direction, the third retro-reflective retro configuration may be offset in a vertical direction.

[0068] In one or more example methods, the method comprises receiving S110, from the WD, a third signal using a third plurality of antennas of the antenna array in the third retro-reflective configuration. In one or more example methods, the geometrical center point of the third plurality of antennas is offset from the geometrical center point of the first plurality of antennas and the geometrical center point of the second plurality of antennas. In one or more example methods, the geometrical center point of the third plurality of antennas is offset from the geometrical center point of the first plurality of antennas and / or the geometrical center point of the second plurality of antennas in one or more of a vertical direction and a horizontal direction of the antenna array. Receiving S110 corresponds to transmitting S202 performed in method 200 of Fig. 4.

[0069] In one or more example methods, the method comprises retransmitting S112 the signal using the third plurality of antennas of the antenna array in the third retro-reflective configuration. In one or more example methods, retransmitting S112 the third signal using the third plurality of antennas, such as antenna elements, of the antenna array in the second retro-reflective configuration comprises activating the third plurality of antennas for a shorter duration than activating the first plurality of antennas for retransmitting S104 the first signal using the plurality of antennas of the antenna array in the first retro-reflective configuration.

[0070] In one or more example methods, the first signal and the second signal and / or the third signal are different parts of a continuous signal or separate signals. In one or more example methods, the WD may continuously transmit the signal while the retro-reflective node switches between the retro-reflective configurations. In this case, the first signal, and the second, an / or the third signal are different parts, such as parts offset in time, of a continuous signal. In one or more example methods, the WD may transmit a first separate signal for reflection using the first retro- reflective configuration, a second separate signal for reflection using the second retro-reflective configuration, and third separate signal for reflection using the third retro-reflective configuration.

[0071] Fig. 4 shows a flow diagram of an example method 200, performed by a wireless device according to the disclosure, for positioning of the WD. The wireless device is the wireless device disclosed herein, such as wireless device 300 of Fig. 1 , and Fig. 7.

[0072] In one or more example methods, the method 200 comprises receiving S201 from a radio network node, a signal configuring the WD to use a retro-reflective node, such as a retro- reflective array, to determine a position of the WD. In one or more example methods, the signal configuring the WD to use a retro-reflective node to determine a position of the WD comprises information indicative of a number of retro-reflective configurations, such as the number of retro- reflective modes, their sequence, and / or their respective durations. In one or more example methods, the information is indicative of a gap of inactivity, during which the retro-reflective node does not reflect or reflects inefficiently. A retro-reflective mode can herein also be referred to as a self-conjugating mode. In one or more examples, receiving S201 corresponds to sending S301 in the method 300 of Fig. 5.

[0073] In one or more example methods, the signal configuring the WD to use a retro-reflective node to determine a position of the WD comprises information indicative of whether the retro-reflective node is time-synchronized. The time-synchronization may be used by the WD to locate a beginning of the sequence of modes, such as the sequency of reflected signals. Upon the retro- reflective node being time-synchronized, the information may comprise an offset within a radio frame (which may be indicated in number of slots and / or symbols) and / or a periodicity suffice. Upon the retro-reflective node being non-synchronized, other methods may be used for the WD to locate the start of the sequence. In one or more example methods, the retro-reflective node may activate each of the self-conjugating modes, such as each of the retro-reflective configurations for different durations.

[0074] In one or more example methods, the signal may comprise a notification from the radio network node that retro-reflective nodes, such as nodes having van Atta arrays, such as van Atta anchors, are deployed in the environment of the WD. In one or more example methods, the signal, such as the notification, may be received by a broadcasted System Information Block (SIB) message. In one or more example methods, the signal may be a WD-specific Radio Resource control (RRC) signaling. In one or more example methods, the signaling may be sidelink signaling, where a WD notifies peer WDs about the presence of retro-reflective nodes. The notification may for example be received via sidelink when a WD is co-located with the retro-reflective node and the WD is responsible for the signaling for the retro-reflective node, for example when the retro-reflective node is a WD-type anchor.

[0075] In one or more example methods, the signal configuring the WD to use a retro-reflective array to determine a position of the WD comprises information indicative of frequency resources in which the WD can transmit signals to the node having an antenna array with an adaptable retro- reflective configuration. In one or more examples, the information may be indicative of resources blocks (RBs), such as a block of contiguous RBs. This block may comprise a plurality of retro-reflective channels, such as anchor channels, each consisting of one or more contiguous RBs. Different WDs may access different channels at the same time without their signals interfering with each other. In one or more example methods, the radio network node, or a coordinating WD, may grant access to retro-reflective channels for the WD. In one or more example methods, the access may be granted by the radio network node or the coordinating WD, in response to a request for access from the WD. In one or more example methods, the WD selects a retro-reflective channel at random when needed, based on pre-configured parameters to coordinate the random access. The selected channel may be selected out of the plurality of retro-reflective channels indicated by the radio network node.

[0076] In one or more example methods, the signal configuring the WD to use a retro-reflective array to determine a position of the WD comprises information indicative of time resources in which the WD can transmit signals to the node having an antenna array with an adaptable retro-reflective configuration.

[0077] Method 200 comprises transmitting S202, to a retro-reflective node, such as a node having an antenna array with an adaptable retro-reflective configuration, a signal. The signal may be a pilot signal, such as a Sounding Reference Signal (SRS). In one or more example methods, transmitting S202 may comprise transmitting one continuous signal and receiving the first reflected, such as relayed signal, and the second reflected signal, based on the one continuous signal. In one or more example methods, transmitting S202 comprises transmitting S202A a first signal. In one or more example methods, transmitting S202 comprises transmitting S202B a second signal. The second signal may be transmitted prior to or after receiving S204 the first reflected signal. In one or more example methods, transmitting S202 comprises transmitting S202C a third signal. The third signal may be transmitted prior to or after receiving S206 the second reflected signal. Transmitting S202 is similar to receiving S102, S106, and S110 in method 100 of Fig. 3. In one or more examples, transmitting S202A corresponds to receiving S102 in method 100 of Fig. 3. In one or more examples, transmitting S202B corresponds to receiving S106 in method 100 of Fig. 3. In one or more examples, transmitting S202C corresponds to receiving S110 in method 100 of Fig. 3.

[0078] In one or more example methods, the method 200 comprises receiving S203, from the retro reflective node, such as the node having an antenna array with an adaptable retro-reflective configuration, a signal indicative of the reflected signal out of the first reflected signal and the second reflected signal to be used as a reference signal. In one or more examples, receiving S203 corresponds to transmitting S103 in method 100 of Fig. 3.

[0079] Method 200 comprises receiving S204, from the retro reflective node, such as the node having an antenna array with an adaptable retro-reflective configuration, a first reflected signal of the transmitted signal. In one or more example methods, the first reflected signal is a reference signal. In one or more examples, receiving S204 corresponds to retransmitting S104 in method 100 of Fig. 3.

[0080] Method 200 comprises receiving S206, from the node having an antenna array with an adaptable retro-reflective configuration, a second reflected signal of the transmitted signal. In one or more examples, receiving S206 corresponds to retransmitting S108 in method 100 of Fig. 3.

[0081] Method 200 comprises determining S208, based on the first reflected signal, such as the reference signal, and the second reflected signal a first measurement value indicative of a spatial direction of the wireless device relative to the node. The first measurement value may be one of kxand ky. In other words, switching the retro-reflective configuration to reflect signals from the WD with reflective beams having offset center of origins generates a phase shift that relates to the angle to the WD from the retro reflective node. This allows a wireless device, such as a single antenna transmitter WD, to compute its spatial angle towards the retro-reflective node. Thereby, an overall complexity of the wireless communication network may be reduced. The first measurement value may be determined based on a phase shift, such as a phase shift determined based on the first reflected signal, such as the reference signal, and the second reflected signal.

[0082] In one or more example methods, method 200 comprises receiving S210, from the node having an antenna array with an adaptable retro-reflective configuration, a third reflected signal of the transmitted signal. In one or more examples, receiving S210 corresponds to retransmitting S112 in method 100 of Fig. 3.

[0083] In one or more example methods, the method 200 comprises determining S212, based on the first reflected signal, such as the reference signal, and the third reflected signal a second measurement value indicative of a spatial direction of the wireless device relative to the node. The second measurement value may be the other parameter of kxand kythat is not the first measurement value.

[0084] Fig. 5 shows a flow diagram of an example method 300, performed by a radio network node according to the disclosure, for enabling positioning of a WD. The radio network node is the radio network node disclosed herein, such as radio network node 400 of Fig. 1 , and Fig. 8.

[0085] The method 300 comprises sending S301 to the WD, a signal configuring the WD to use a retro-reflective array to determine a position of the WD. In one or more example methods, the signal configuring the WD to use a retro-reflective array to determine a position of the WD comprises information indicative of a number of retro-reflective configurations, their sequence, and / or their respective durations. In one or more example methods, the signal configuring the WD to use a retro-reflective array to determine a position of the WD comprises information indicative of whether the node having an antenna array with an adaptable retro-reflective configuration is time-synchronized. In one or more example methods, the signal configuring the WD to use a retro-reflective array to determine a position of the WD comprises information indicative of time and / or frequency resources in which the WD can transmit signals to the node having an antenna array with an adaptable retro-reflective configuration. In one or more examples, sending S301 corresponds to receiving S201 in method 100 of Fig. 3. Fig. 6 shows a block diagram of an example retro-reflective node 500 according to the disclosure. The retro-reflective node 500 comprises memory circuitry 501 , processor circuitry

[0086] 502, and a wireless interface 503. The retro-reflective node 500 may be configured to perform any of the methods disclosed in Fig. 3. In other words, the retro-reflective node 500 may be configured for enabling positioning of a WD.

[0087] The retro-reflective node 500 is configured to communicate with a user equipment, such as the WD disclosed herein, using a wireless communication system.

[0088] The wireless interface 503 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.

[0089] The retro-reflective node 500 is configured to receive, for example via the wireless interface

[0090] 503, from the WD, a first signal using a first plurality of antennas of the antenna array in a first retro-reflective configuration.

[0091] The retro-reflective node 500 is configured to retransmit, for example via the wireless interface 503, the signal using the first plurality of antennas of the antenna array in the first retro-reflective configuration.

[0092] The retro-reflective node 500 is configured to reconfigure, for example via the processor circuitry 502, the retro-reflective configuration of the antenna array from the first retro-reflective configuration to a second retro-reflective configuration.

[0093] The retro-reflective node 500 is configured to receive, for example via the wireless interface 503, from the WD, a second signal using a second plurality of antennas of the antenna array in the second retro-reflective configuration, and

[0094] The retro-reflective node 500 is configured to retransmit, for example via the wireless interface 503, the signal using the plurality of antennas of the antenna array in the second retro-reflective configuration.

[0095] Processor circuitry 502 is optionally configured to perform any of the operations disclosed in Fig. 3 (such as any one or more of S102, S103, S104, S105, S106, S108, S109, S110, S112). The operations of the retro-reflective node 500 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 501) and are executed by processor circuitry 502).

[0096] Furthermore, the operations of the retro-reflective node 500 may be considered a method that the retro-reflective node 500 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.

[0097] Memory circuitry 501 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), or other suitable device. In a typical arrangement, memory circuitry 401 may include a nonvolatile memory for long term data storage and a volatile memory that functions as system memory for processor circuitry 502. Memory circuitry 501 may exchange data with processor circuitry 502 over a data bus. Control lines and an address bus between memory circuitry 501 and processor circuitry 502 also may be present (not shown in Fig. 6). Memory circuitry 501 is considered a non-transitory computer readable medium. Memory circuitry 501 may be configured to store information, such as information regarding the retro-reflective configurations in a part of the memory.

[0098] Fig. 7 shows a block diagram of an example wireless device 300 according to the disclosure. The wireless device 300 comprises memory circuitry 301 , processor circuitry 302, and a wireless interface 303. The wireless device 300 may be configured to perform any of the methods disclosed in Fig. 4. In other words, the wireless device 300 may be configured for positioning of the wireless device.

[0099] The wireless device 300 is configured to communicate with a network node, such as the radio network node 400 and / or the retro-reflective node 500 disclosed herein, using a wireless communication system.

[0100] The wireless device 300 is configured to transmit a signal, such as via the wireless interface 303, to the retro-reflective node, such as a node having an antenna array with an adaptable retro-reflective configuration.

[0101] The wireless device 300 is configured to receive, such as via the wireless interface 303, from the retro-reflective node, a first reflected signal of the transmitted signal.

[0102] The wireless device 300 is configured to receive, such as via the wireless interface 303, from the retro-reflective node, a second reflected signal of the transmitted signal, and The wireless device 300 is configured to determine, such as via the processor circuitry 302, based on the first reflected signal and the second reflected signal a first measurement value indicative of a spatial direction of the wireless device relative to the retro-reflective node.

[0103] The wireless interface 303 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.

[0104] The wireless device 300 is optionally configured to perform any of the operations disclosed in Fig. 4 (such as any one or more of S201 , S202, S203, S204, S206, S208, S210, S212). The operations of the wireless device 300 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) and are executed by processor circuitry 302).

[0105] Furthermore, the operations of the wireless device 300 may be considered a method that the wireless device 300 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.

[0106] Memory circuitry 301 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), or other suitable device. In a typical arrangement, memory circuitry 301 may include a nonvolatile memory for long term data storage and a volatile memory that functions as system memory for processor circuitry 302. Memory circuitry 301 may exchange data with processor circuitry 302 over a data bus. Control lines and an address bus between memory circuitry 301 and processor circuitry 302 also may be present (not shown in Fig. 7). Memory circuitry 301 is considered a non-transitory computer readable medium.

[0107] Memory circuitry 301 may be configured to store information (such as information indicative of retro-reflective configurations of the retro-reflective node, and / or one or more measurement values) in a part of the memory.

[0108] Fig. 8 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. 5. In other words, the network node 400 may be configured for enabling positioning of a WD.

[0109] The network node 400 is configured to communicate with a wireless device, such as the WD 300 disclosed herein, and / or with the retro-reflective node 500 disclosed herein, using a wireless communication system.

[0110] 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.

[0111] The network node 400 is configured to send, for example via the wireless interface 403, to the WD, a signal configuring the WD to use a retro-reflective node to determine a position of the WD.

[0112] Processor circuitry 402 is optionally configured to perform any of the operations disclosed in Fig. 5 (such as any one or more of S301). The operations of the 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).

[0113] Furthermore, the operations of the network node 400 may be considered a method that the 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.

[0114] 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), or other suitable device. In a typical arrangement, memory circuitry 401 may include a nonvolatile 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. 8). Memory circuitry 401 is considered a non-transitory computer readable medium. Memory circuitry 401 may be configured to store information (such as information indicative of retro-reflective configurations of the retro-reflective node, and / or one or more measurement values) in a part of the memory. Examples of methods and products (node having an antenna array with an adaptable retro- reflective configuration, wireless device, and radio network node) according to the disclosure are set out in the following items:

[0115] Item 1 . A method performed by a retro-reflective node, for enabling positioning of a wireless device, WD, the method comprising: receiving (S102), from the WD, a first signal using a first plurality of antennas of the antenna array in a first retro-reflective configuration, retransmitting (S104) the signal using the first plurality of antennas of the antenna array in the first retro-reflective configuration, reconfiguring (S105) the retro-reflective configuration of the antenna array from the first retro-reflective configuration to a second retro-reflective configuration, receiving (S106), from the WD, a second signal using a second plurality of antennas of the antenna array in the second retro-reflective configuration, and retransmitting (S108) the signal using the plurality of antennas of the antenna array in the second retro-reflective configuration.

[0116] Item 2. The method according to Item 1 , wherein the first plurality of antennas is a reference subset of antennas of the antenna array.

[0117] Item 3. The method according to any one of the previous Items, wherein a geometrical center point of the second plurality of antennas is offset from a geometrical center point of the first plurality of antennas.

[0118] Item 4. The method according to Item 3, wherein the first plurality antennas and the second plurality of antennas are symmetrically spaced around their respective geometrical center point.

[0119] Item 5. The method according to Item 3 or 4, wherein the geometrical center point of the second plurality of antennas is offset from the geometrical center point of the first plurality of antennas in one or more of a vertical direction and a horizontal direction of the antenna array.

[0120] Item 6. The method according to any one of the previous Items, wherein the method comprises: reconfiguring (S109) the retro-reflective configuration of the antenna array from the second retro-reflective configuration to a third retro-reflective configuration, receiving (S110), from the WD, a third signal using a third plurality of antennas of the antenna array in the third retro-reflective configuration, and retransmitting (S112) the signal using the third plurality of antennas of the antenna array in the third retro-reflective configuration.

[0121] Item 7. The method according to Item 6, wherein the geometrical center point of the third plurality of antennas is offset from the geometrical center point of the first plurality of antennas and the geometrical center point of the second plurality of antennas.

[0122] Item 8. The method according to Item 7, wherein the geometrical center point of the third plurality of antennas is offset from the geometrical center point of the first plurality of antennas and / or the geometrical center point of the second plurality of antennas in one or more of a vertical direction and a horizontal direction of the antenna array.

[0123] Item 9. The method according to any one of the previous Items, wherein the first signal and the second signal and / or the third signal are different parts of a continuous signal or separate signals.

[0124] Item 10. The method according to any one of the previous Items, wherein retransmitting (S104) the signals using the first plurality of antennas of the antenna array in the first retro-reflective configuration comprises activating the first plurality of antennas for a longer duration than activating the second plurality of antennas for retransmitting (S108) the signal using the plurality of antennas of the antenna array in the second retro- reflective configuration.

[0125] Item 11. The method according to any one of the previous Items, wherein the method comprises: transmitting (S103), to the WD, a signal indicative of the transmission of the signal using the first plurality of antennas of the antenna array in the first retro- reflective configuration.

[0126] Item 12. A method performed by a wireless device, WD, for positioning of the wireless device, the method comprising: transmitting (S202), to a retro-reflective node, a signal, receiving (S204), from the retro-reflective node, a first reflected signal of the transmitted signal, receiving (S206), from the retro-reflective node, a second reflected signal of the transmitted signal, and determining (S208), based on the first reflected signal and the second reflected signal a first measurement value indicative of a spatial direction of the wireless device relative to the retro-reflective node.

[0127] Item 13. The method according to Item 12, wherein the method comprises: receiving (S210), from the retro-reflective node, a third reflected signal of the transmitted signal, and determining (S212), based on the first reflected signal and the third reflected signal a second measurement value indicative of a spatial direction of the wireless device relative to the retro-reflective node.

[0128] Item 14. The method according to any one of the Items 12 to 13, wherein the method comprises: receiving (S203), from the retro-reflective node, a signal indicative of the reflected signal out of the first reflected signal and the second reflected signal to be used as a reference signal.

[0129] Item 15. The method according to any one of the Items 12 to 14, wherein the first reflected signal is a reference signal.

[0130] Item 16. The method according to any one of the Items 12 to 15, wherein the method comprises: receiving (S201 ), from a radio network node, a signal configuring the WD to use a retro-reflective array to determine a position of the WD.

[0131] Item 17. The method according to Item 16, wherein the signal configuring the WD to use a retro-reflective array to determine a position of the WD comprises one or more of: information indicative of a number of retro-reflective configurations, their sequence, and / or their respective durations, information indicative of whether the node having an antenna array with an adaptable retro-reflective configuration is time-synchronized, information indicative of time and / or frequency resources in which the WD can transmit signals to the node having an antenna array with an adaptable retro- reflective configuration.

[0132] Item 18. A method performed in a radio network node, for enabling positioning of a wireless device, WD, the method comprising: sending (S301 ), to the WD, a signal configuring the WD to use a retro-reflective node to determine a position of the WD.

[0133] Item 19. The method according to Item 18, wherein the signal configuring the WD to use a retro-reflective node to determine a position of the WD comprises one or more of: information indicative of a number of retro-reflective configurations, their sequence, and / or their respective durations, information indicative of whether the retro-reflective node is time-synchronized, information indicative of time and / or frequency resources in which the WD can transmit signals to the retro-reflective node.

[0134] Item 20. A retro-reflective node comprising memory circuitry, processor circuitry, and a wireless interface, wherein the retro-reflective node is configured to perform any of the methods according to any of Items 1-11.

[0135] Item 21. A wireless device comprising memory circuitry, processor circuitry, and a wireless interface, wherein the wireless device is configured to perform any of the methods according to any of Items 12-17.

[0136] Item 22. 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 18-19.

[0137] 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.

[0138] It may be appreciated that Figures 1-8 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.

[0139] 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.

[0140] 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 claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as any sub-combination or variation of any sub-combination

[0141] It is to be noted that the word "comprising" does not necessarily exclude the presence of other elements or steps than those listed.

[0142] 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.

[0143] It is to be noted that the term "indicative of may be seen as “associated with”, “related to”, “descriptive of’, “characterizing”, and / or “defining”. The terms “indicative of”, “associated with”, “related to”, “descriptive of’, “characterizing”, and “defining” can be used interchangeably. The term “indicative of” can be seen as indicating a relation. For example, weight data indicative of weight may comprise one or more weight parameters.

[0144] It is to be noted that the word "based on" may be seen as “as a function of” and / or “derived from”. The terms “based on” and “as a function of’ can be used interchangeably. For example, a parameter determined “based on” a data set can be seen as a parameter determined “as a function of” the data set. In other words, the parameter may be an output of one or more functions with the data set as an input.

[0145] A function may be characterizing a relation between an input and an output, such as mathematical relation, a database relation, a hardware relation, logical relation, and / or other suitable relations.

[0146] 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.

[0147] 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.

[0148] 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 computerexecutable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and non-removable 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.

[0149] 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

CLAIMS1 . A method performed by a retro-reflective node, for enabling positioning of a wireless device, WD, the method comprising: receiving (S102), from the WD, a first signal using a first plurality of antennas of the antenna array in a first retro-reflective configuration, retransmitting (S104) the first signal using the first plurality of antennas of the antenna array in the first retro-reflective configuration, reconfiguring (S105) the retro-reflective configuration of the antenna array from the first retro-reflective configuration to a second retro-reflective configuration, receiving (S106), from the WD, a second signal using a second plurality of antennas of the antenna array in the second retro-reflective configuration, and retransmitting (S108) the second signal using the plurality of antennas of the antenna array in the second retro-reflective configuration.

2. The method according to claim 1 , wherein the first plurality of antennas is a reference subset of antennas of the antenna array.

3. The method according to any one of the previous claims, wherein a geometrical center point of the second plurality of antennas is offset from a geometrical center point of the first plurality of antennas.

4. The method according to claim 3, wherein the first plurality antennas and the second plurality of antennas are symmetrically spaced around their respective geometrical center point.

5. The method according to claim 3 or 4, wherein the geometrical center point of the second plurality of antennas is offset from the geometrical center point of the first plurality of antennas in one or more of a vertical direction and a horizontal direction of the antenna array.

6. The method according to any one of the previous claims, wherein the method comprises: reconfiguring (S109) the retro-reflective configuration of the antenna array from the second retro-reflective configuration to a third retro-reflective configuration,receiving (S110), from the WD, a third signal using a third plurality of antennas of the antenna array in the third retro-reflective configuration, and retransmitting (S112) the signal using the third plurality of antennas of the antenna array in the third retro-reflective configuration.

7. The method according to claim 6, wherein the geometrical center point of the third plurality of antennas is offset from the geometrical center point of the first plurality of antennas and the geometrical center point of the second plurality of antennas.

8. The method according to claim 7, wherein the geometrical center point of the third plurality of antennas is offset from the geometrical center point of the first plurality of antennas and / or the geometrical center point of the second plurality of antennas in one or more of a vertical direction and a horizontal direction of the antenna array.

9. The method according to any one of the previous claims, wherein the first signal and the second signal and / or the third signal are different parts of a continuous signal or separate signals.

10. The method according to any one of the previous claims, wherein retransmitting (S104) the signals using the first plurality of antennas of the antenna array in the first retro- reflective configuration comprises activating the first plurality of antennas for a longer duration than activating the second plurality of antennas for retransmitting (S108) the signal using the plurality of antennas of the antenna array in the second retro-reflective configuration.11 . The method according to any one of the previous claims, wherein the method comprises: transmitting (S103), to the WD, a signal indicative of the transmission of the signal using the first plurality of antennas of the antenna array in the first retro-reflective configuration.

12. A method performed by a wireless device, WD, for positioning of the wireless device, the method comprising: transmitting (S202), to a retro-reflective node, a signal, receiving (S204), from the retro-reflective node, a first reflected signal of the transmitted signal,receiving (S206), from the retro-reflective node, a second reflected signal of the transmitted signal, and determining (S208), based on the first reflected signal and the second reflected signal, a first measurement value indicative of a spatial direction of the wireless device relative to the node.

13. The method according to claim 12, wherein the method comprises: receiving (S210), from the retro-reflective node, a third reflected signal of the transmitted signal, and determining (S212), based on the first reflected signal and the third reflected signal a second measurement value indicative of a spatial direction of the wireless device relative to the retro-reflective node.

14. The method according to any one of the claims 12 to 13, wherein the method comprises: receiving (S203), from the retro-reflective node, a signal indicative of the reflected signal out of the first reflected signal and the second reflected signal to be used as a reference signal.

15. The method according to any one of the claims 12 to 14, wherein the first reflected signal is a reference signal.

16. The method according to any one of claims 12 to 15, wherein the method comprises: receiving (S201 ), from a radio network node, a signal configuring the WD to use a retro-reflective array to determine a position of the WD.

17. The method according to claim 16, wherein the signal configuring the WD to use a retro- reflective array to determine a position of the WD comprises one or more of: information indicative of a number of retro-reflective configurations, their sequence, and / or their respective durations, information indicative of whether the retro-reflective node is time-synchronized, information indicative of time and / or frequency resources in which the WD can transmit signals to the retro-reflective node.

18. A method performed in a radio network node, for enabling positioning of a wireless device, WD, the method comprising: sending (S301 ) to the WD, a signal configuring the WD to use a retro-reflective array to determine a position of the WD.

19. The method according to claim 18, wherein the signal configuring the WD to use a retro- reflective node to determine a position of the WD comprises one or more of: information indicative of a number of retro-reflective configurations, their sequence, and / or their respective durations, information indicative of whether the retro-reflective node is time-synchronized, information indicative of time and / or frequency resources in which the WD can transmit signals to the retro-reflective node.

20. A retro-reflective node comprising memory circuitry, processor circuitry, and a wireless interface, wherein the retro-reflective node is configured to perform any of the methods according to any of claims 1-11.

21. A wireless device comprising memory circuitry, processor circuitry, and a wireless interface, wherein the wireless device is configured to perform any of the methods according to any of claims 12-17.

22. 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 18-19.

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