POSITIONING IN A WIRELESS COMMUNICATION NETWORK

Abstract

A method for operating a network node (100) in a wireless communication network is provided. The method comprises transmitting at least one beamformed signal (20-27). Each one of the at least one beamformed signal (20-27) is indicative of a respective positioning information. The respective positioning information is indicative of a respective virtual reference point (40-47) which is offset from a position of a transmit point (50) of the wireless communication network used for transmitting the at least one beamformed signal (20-27). The beamformed signal (20-27) is suitable for enabling a positioning measurement of a wireless communication device (200).

Claims

1. A method for operating a network node in a wireless communication network, the method comprising: transmitting at least one beamformed signal, wherein each one of the at least one beamformed signal is indicative of a respective positioning information, wherein the respective positioning information is indicative of a respective virtual reference point which is offset from a position of a transmit point of the wireless communication network used for transmitting the at least one beamformed signal, wherein the beamformed signal is suitable for enabling a positioning measurement of a wireless communication device.

2. The method of claim 1, further comprising: transmitting a message indicating that the respective positioning information of the at least one beamformed signal is indicative of the respective virtual reference point.

3. The method of claim 1, further comprising: transmitting a positioning information mapping indicative of a mapping of the respective positioning information to the respective virtual reference point for each of the at least one beamformed signal.

4. The method of claim 1, further comprising: transmitting a message indicating that the respective virtual reference points are dynamically changed with subsequent beamformed signals of a same transmit direction.

5. The method of claim 1, wherein the at least one beamformed signal comprises multiple beamformed signals, wherein the virtual reference points of the multiple beamformed signals are offset from the position of the transmit point along a respective transmit direction of the respective beamformed signal.

6. The method of claim 1, wherein the positioning information is indicative of a direction information for the device to determine its position based on the direction information, wherein the direction information is indicative of a respective transmit direction of the beamformed signal.

7. The method of claim 1, wherein the positioning information is indicative of a virtual timing information for the device to determine its position, wherein the virtual timing information is based on a distance between the virtual reference point and the position of the transmit point.

8. The method of claim 7, wherein the virtual timing information comprises a phase information to be used for transmitting the corresponding beamformed signal, wherein the phase information is based on a distance between the virtual reference point and the position of the transmit point.

9. The method of claim 1, wherein the positioning information is indicative of a timing correction information for the device to determine its position based on a timing information of the respective beamformed signal and the timing correction information, wherein the timing correction information is based on a distance between the virtual reference point and the position of the transmit point.

10. The method of claim 1, wherein the positioning information is indicative of a power correction information for the device to determine its position based on a received power of the respective beamformed signal and the power correction information, wherein the power correction information is based on a distance between the virtual reference point and the position of the transmit point.

11. The method of claim 1, further comprising: transmitting a power correction mapping indicative of a mapping of the respective positioning information to a power correction information for each of the at least one beamformed signal, the power correction information being used by the device to determine its position based on a received power of the respective beamformed signal and the power correction information, wherein the power correction information is based on a distance between the virtual reference point and the position of the transmit point.

12. The method of claim 10, wherein the power correction information is based additionally on a path propagation model.

13. The method of claim 1, wherein a transmit power used for transmitting the beamformed signal is based on a distance between the transmit point and the virtual reference point.

14. The method of claim 13, wherein the transmit power is based additionally on a path propagation model.

15. The method of claim 1, further comprising: determining, for each one of the at least one beamformed signal, the respective virtual reference point, wherein the respective virtual reference point is offset from the position of the transmit point of the wireless communication network used for transmitting the at least one beamformed signal.

16. The method of claim 1, further comprising: for each one of the at least one beamformed signal, determining the respective positioning information, wherein the respective positioning information is indicative of the respective virtual reference point.

17. A method for determining a position of a wireless communication device in a wireless communication network, the method comprising: receiving at least one beamformed signal, wherein each one of the at least one beamformed signal is indicative of a respective positioning information. receiving an indication indicating that the respective positioning information is indicative of a respective virtual reference point which is offset from a position of a transmit point of the wireless communication network used for transmitting the at least one beamformed signal, and determining the position of the wireless communication device based on the positioning information and the indication.

18. The method of claim 17, further comprising: receiving a message indicating that the respective positioning information of the at least one beamformed signal is indicative of the respective virtual reference point, determining the position of the wireless communication device based on the indication that the at least one beamformed signal is indicative of the respective virtual reference point.

19. The method of claim 17, further comprising: receiving a positioning information mapping indicative of a mapping of the respective positioning information to the respective virtual reference point for each of the at least one beamformed signal, determining the position of the wireless communication device based on the positioning information mapping.

20-26. (canceled)

27. A network node in a wireless communication network, the network node comprising: a transmitter configured to transmit at least one beamformed signal, control circuitry configured to determine, for each one of the at least one beamformed signal, a respective virtual reference point, wherein the respective virtual reference point is offset from a position of a transmit point of the wireless communication network used for transmitting the at least one beamformed signal, and determine, for each one of the at least one beamformed signal, a respective positioning information, wherein the respective positioning information is indicative of the respective virtual reference point, wherein the beamformed signal is suitable for enabling a positioning measurement of a wireless communication device.

28-30. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Embodiments of the invention will be described in more detail with reference to the accompanying drawings.

[0066] FIG. 1 shows schematically a wireless communication network comprising a network node and a wireless communication device.

[0067] FIG. 2 shows schematically a wireless communication network comprising a network node and a wireless communication device according to various examples.

[0068] FIG. 3 shows schematically a method according to various examples in which a virtual reference point is offset from a real transmit point.

[0069] FIG. 4 shows a flowchart of a message flow between a network node and a device according to various examples.

[0070] FIG. 5 shows a flowchart of a message flow between a network node and a device according to further examples.

[0071] FIG. 6 shows schematically a network node according to various examples.

[0072] FIG. 7 shows schematically a device according to various examples.

[0073] FIG. 8 shows a flowchart of a method performed by a network node according to various examples.

[0074] FIG. 9 shows a flowchart of a method performed by a device according to various examples.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0075] In the following, exemplary embodiments of the present invention will be described in more detail. It is to be understood that the features of the various exemplary embodiments described herein may be combined with each other unless specifically noted otherwise. Any coupling between components or devices shown in the figures may be a direct or indirect coupling unless specifically noted otherwise.

[0076] FIG. 2 illustrates a positioning technology using beamformed positioning reference signals. A beamformed positioning reference signal is a radio frequency signal which is transmitted in a defined direction using beamforming. Essentially, the beamformed positioning reference signal may have a main lobe in a defined direction and may thus essentially cover a certain sector only. An opening angle of the sector may be in a range of a few degrees, for example 5° to 30° in horizontal and/or vertical direction. The beamformed positioning reference signal may be transmitted in a downlink direction and may comprise information which enables a receiving device to determine its position based on information provided in the beamformed positioning reference signal only. Using a plurality of beamformed positioning reference signals from different directions may increase accuracy of positioning at the device. In the following, a beamformed positioning reference signal will also be called beamformed signal or positioning reference signal.

[0077] Returning to FIG. 2. A network node 100 comprises an antenna array 50 configured to transmit beamformed signals 20 to 27 in different directions 30 to 37. The antenna array 50 may comprise a plurality of antenna elements for establishing the transmission of the beamformed signals 20 to 27. The antenna array 50 may be located nearby the network node 100 or spaced apart from the network node 100. Each beamformed signal 20 to 27 is transmitted from the antenna array 50 such that the beamformed signals 20 to 27 share a common origin which is located at the antenna array 50. The origin or position of the transmit point from where the beamformed signals 20 to 27 are transmitted is the same for all beamformed signals 20 to 27 and corresponds to the position of the antenna array 50. Therefore, in the following, the position of the transmit point from where the beamformed signals 20 to 27 are transmitted will also be designated with reference sign 50, i.e. origin 50 or (real) transmit point 50.

[0078] Each beamformed signal 20 to 27 includes direction information indicating a direction of the beam. The directions of the beams are indicated in FIG. 2 by reference signs 30 to 37. Direction 30 indicates the direction of beamformed signal 20, direction 31 indicates the direction of beamformed signal 21, direction 32 indicates the direction of beamformed signal 22 and so on. The direction information may be indicated in the beamformed signal by an azimuth and elevation angle. However, in case a two dimensional positioning is required only, the direction information may be indicated in the beamformed signal by an azimuth only.

[0079] Each beamformed signal 20 to 27 includes a position information indicating a virtual origin from which each of the beamformed signals 20 to 27 is virtually transmitted. “Virtually transmitted” means that the beamformed signal has been physically transmitted from origin 50, but from the position information it appears as if the beamformed signal has been transmitted from a virtual reference point which is offset from the origin 50 along the direction of the corresponding beamformed signal. For example, beamformed signal 20 includes a position information indicating a virtual reference point 40 which is offset from the physical origin 50 along the direction 30. As can be seen in FIG. 2, the virtual reference point 40 is offset in the direction 30 “behind” the physical origin 50 as seen from a device which is allocated in a sector covered by the beamformed signal 20. Furthermore, as shown in FIG. 2, beamformed signal 21 includes a position information indicating a virtual reference point 41 which is offset from the physical origin 50 along the direction 31. The virtual reference point may also be offset such that it appears from the receiving device as if the virtual reference point is closer to the device than the physical origin 50. Such an example is shown in connection with beamformed signal 27. Beamformed signal 27 may include a position information indicating a virtual reference point 47 which is offset from the physical origin 50 along the direction 37. The virtual reference point 47 is offset in the direction 37 “in front of” the physical origin 50 as seen from a device which is located in a sector covered by the beamformed signal 27.

[0080] The position information indicating the origin may comprise an absolute global position or a relative position with respect to a predefined global position or a predefined reference system. Each beamformed signal 20 to 27 includes a virtual timing information which enables a receiving device to determine a distance between the device and the corresponding virtual reference point 40 to 47 based on the time of flight of the received beamformed signal 20 to 27. In the example shown in FIG. 2, a device 200 is located in a sector covered by beamformed signal 21. Upon receiving the beamformed signal 21, the device 200 may determine its position with respect to the virtual reference point 41 based on the direction information and virtual timing information included in the beamformed signal 21. In connection with the position information concerning the virtual reference point 41, the device 200 may determine its global position or relative position with respect to a reference system.

[0081] One effect of the above described concept is that, from an algorithm perspective, for the device 200 there is no difference whether its position estimate is based on the virtual origin 41 of the beamformed signal 21 or based on the “real” origin 50 of the beamformed signal 21. However, the network node 100 does not reveal its position. A limitation of the positions of the virtual reference points may be a time window in which the positioning reference signal needs to be transmitted. If the virtual position is too far away it may not hit the measurement window at the device.

[0082] FIG. 3 shows the above described concepts in more detail. The beamformed signal 21 may comprise a beamformed positioning reference signal (PRS). The virtual timing information included in the positioning reference signal 21 may indicate a timestamp information from which the receiving device 200 may determine the point of time when the positioning reference signal 21 was allegedly transmitted from the virtual reference point 41. The traveling time of the positioning reference signal 21 for propagating from the virtual reference point 41 to the device 200 may be determined based on the virtual timing information. For example, the network node 100 may add a delay or phase shift (either positive or negative depending on the direction in which the virtual reference point is offset from the origin 50 along the direction 31) to emulate that the beamformed signal 21 has traveled a longer or shorter distance than the actual distance from the origin 50. The delay represents the time it would take the beamformed signal to travel the distance between the virtual reference point 41 and the origin 50. The phase shift represents a shift in phase of the beamformed signal which would occur when the beamformed signal would travel from the virtual reference point 41 to the origin 50. In FIG. 3, the beamformed signal 21 is transmitted from the origin 50.

[0083] Usually, as shown in FIG. 1 without offset virtual reference points, the device 200 obtains a Time of Arrival (ToA). The ToA is determined by estimating time delay obtained from the cross-correlation output of the received PRS and a replica/stored PRS at the device 200. The replica/stored PRS may be synchronized to a network timing, for example to a frame structure of the network nodes defined in the communication network. For example, in LTE the network timing may be based on a transmission of synchronization signals, e.g. primary synchronization signal (PSS) and secondary synchronization signal (SSS), and in 5G NR the network timing may additionally be based on information of the synchronization signal block (SSB). The device 200 determines its position based on origin 50, the distance 60 and the direction 31.

[0084] According to the concepts shown in FIG. 2 and FIG. 3, the PRS generated at the network node is modified such that its virtual timing information is also a function of a distance 61 between origin 50 and the virtual reference point 41 and modified by:

Δt=(R −R)/c

[0085] wherein R′ is the location of virtual reference point 41, R is the location of origin 50, and c is the speed of light.

[0086] The PRS generated at the network node indicates a virtual timing information modified by Δt such that the device 200 receiving the generated PRS determines a traveling distance 61 for the PRS traveling from virtual reference point 41 to the device 200. The virtual timing information Δt is equivalent to the distance 62. As described above, the device 200 may perform cross-correlation of the received modified PRS and the replica/stored PRS. The cross-correlation output is further processed in order to obtain a time delay information. The time delay information is further used for determining the distance 61.

[0087] It is to be noticed that the virtual reference points 40 to 47 are different for each beamformed signal 20 to 27. The offsets for the virtual reference points 40 to 47 may be selected individually and may be different for each beamformed signal 20 to 27. However, all beamformed signals may have the same absolute offset, but in different directions. The same absolute offset may lead to the same time offset Δt to be applied for modifying the corresponding virtual timing information of the beamformed signals.

[0088] Furthermore, instead of a timing based distance determination, the distance between the device 200 and the virtual reference points 40 to 47 may be determined based on a reference signal received power (RSRP) based positioning. The distance between the origin 50 and the virtual reference points 40 to 47 may then be associated with a power offset Δp that corresponds to a path loss of Δp induced by the additional virtual propagation path 62. A power correction information may be included in the beamformed signal to provide information for the device 200 to determine the distance 61 between the virtual reference point 41 and the device 200 based on the received power.

[0089] Timing or power information required by the device 200 for determining the distance 61 may be provided in mapping information which may be communicated from the wireless communication network to the device 200 separately from transmitting the beamformed signals 20-27. The beamformed signals 20-27 may then only contain an identifier referencing to timing or power information in the mapping information. In further examples, the beamformed signals 20-27 may be transmitted in specific resources defined in the wireless communication network. The specific resources may be related to timing or power information in the mapping information. Thus, the amount of information communicated in the beamformed signals 20 to 27 may be reduced.

[0090] FIG. 4 shows a flowchart of communication between the network node 100 and the device 200. Steps and transmissions indicated with dashed lines may be optional.

[0091] In step 701 the network node 100 determines for each beamformed signal 20 to 27 a respective virtual reference point 40 to 47. The respective virtual reference points 40 to 47 are each offset from the position of the real transmit point or origin 50 (the antenna array 50 assigned to the network node 100) from which the beamformed signals 20 to 27 will be transmitted. Each of the virtual reference points 40 to 47 is offset from the position of the origin 50 along the respective transmit direction 30 to 37 of the respective beamformed signal 20 to 27.

[0092] In step 702 the network node 100 determines for each beamformed signal 20 to 27 a corresponding positioning information which indicates the respective virtual reference point 40 to 47 for the respective beamformed signal 20 to 27. The positioning information may indicate for example an absolute position of the respective virtual reference point with reference to earth or a relative position of the respective virtual reference point with reference to a reference system defined for the wireless communication network. At 703, the network node 100 and may transmit a message indicating the determined positioning information for the beamformed signals 20 to 27, i.e. the positions of the virtual reference points 40 to 47, for example the absolute position or the relative position of the virtual reference points in a coded form, for example as geographic coordinates. The message may comprise further information, for example a direction information indicating the direction of propagation of the beamformed signals 20 to 27. At 708, the network node 100 may transmit a beamformed signal indicating the positioning information. The beamformed signal may comprise a positioning reference signal. The beamformed signal may include or be indicative of further information, in particular a direction information indicating the direction of propagation of the beamformed signal with respect to the virtual reference point, and a virtual timing information which enables a device receiving the beamformed signal to determine, based on the virtual timing information, a traveling time of the beamformed signal from the virtual reference point to the device. Thus, the distance between the virtual reference point and the device can be estimated.

[0093] As explained above in connection with FIG. 3, the virtual reference point does not correspond to the real origin from which the beamformed signal is transmitted. Therefore, the virtual timing information may be determined such that it considers the propagation time from the real origin to the receiving device 200 (distance 60) and the propagation time from the virtual reference point to the real origin (distance 62). At 801 the device 200 may receive the message indicating the determined positioning information for the beamformed signals 20 to 27. At 806 the device 200 may receive the beamformed signal and may extract the absolute position or the relative position of the virtual reference point from the positioning information indicated in the received beamformed signal. Based on the absolute or relative position of the virtual reference point, the direction information and the virtual timing information, the device 200 may determine at 807 its own position, for example as an absolute position with respect to earth or a relative position with respect to a reference coordinate system.

[0094] In various examples, at 704 the network node 100 may transmit a message to the device 200. The message indicates that the positioning information provided in beamformed positioning reference signals does not indicate the real position of the origin of the beamformed signals, but virtual reference points. The device 200 may receive this message at 802. This information may be useful for the device 200 for the following reasons: When the device is moving, it may receive different beamformed signals from the same network node, but these different beamformed signals have different directions and consequently different virtual reference points. Thus, from the point of view of the device 200, the location of the network node 100 is varying. Due to this varying location, the device may not trust these positioning reference signals and may refuse them. However, by indicating that the positioning reference signals indicate virtual reference points, the device 200 may nevertheless trust in these positioning reference signals and may use them for determining its position. Further, a similar uncertainty may result at the device 200 when the network node 100 varies the virtual reference point for subsequently transmitted positioning reference signal having the same beamforming. However, transmitting the message in step 704 may be optional and the device may use the beamformed signals indicating the virtual reference points without knowing that the indicated virtual reference points do not indicate the real origin of the beamformed signal.

[0095] In further examples, the positioning information may comprise an identifier which identifies, in connection with a positioning information mapping described below, a relative or absolute position of the respective virtual reference point. In a corresponding positioning information mapping a relative or absolute position of the respective virtual reference points may be defined for each identifier.

[0096] In further example, the network node may determine for each beamformed signal 20 to 27 a corresponding resource defined in the wireless communication network. In a corresponding positioning information mapping, a relative or absolute position of the respective virtual reference points may be defined for each resource used for transmitting the beamformed signals 20 to 27.

[0097] For example, at 705 the network node may transmit a message indicating a positioning information mapping. This message may be transmitted once after the device 200 has registered at the network node 100, in regular terms, upon request from the device 200, upon a change in the mapping or according to any other trigger. The message including the mapping may be received by the device at 803.

[0098] The mapping may indicate an assignment of resources to virtual reference points. The resources may be resources defined in the communication network for transmitting downlink information, for example time-frequency resources. The beamformed signal may be transmitted at 708 using the resource assigned to the beamformed signal. The mapping may contribute to reduce the amount of data to be transmitted in the beamformed signals. For example, each beamformed signal may be transmitted at 708 by the network node 100 using the resource assigned to the corresponding beamformed signal; this transmission can implement the reference signal or, more specifically the PRS as described above. In particular, the transmission can have characteristics of a conventional PRS, e.g., sequence design, signal properties, bandwidth, QPSK sequence, etc. The device 200 may receive the beamformed signal at 806 and may determine, based on the mapping and the resource in which the beamformed signal was received, the virtual reference point assigned to this beamformed signal.

[0099] In other examples, the mapping may indicate an assignment of identifiers to virtual reference points. The network node 100 may transmit at 708 a beamformed signal indicating an identifier which is assigned to the virtual reference points of the beamformed signal. The device 200 may receive the beamformed signal at 806. Based on the mapping and the identifier, the device 200 may determine the virtual reference point assigned to this beamformed signal.

[0100] In further examples, the network node 100 may transmit at 706 a message indicating that the virtual reference points are changing dynamically. For example, the network node 100 may vary the position of the virtual reference points for a single direction after each transmission of the beamformed signal in the corresponding direction. In other examples, the network node 100 may vary the position of the virtual reference points in regular intervals. The device 200 may receive the message indicating that the virtual reference points are changing dynamically at 804. Communicating that the virtual reference points are changing dynamically may be useful for the device 200. The device may receive subsequence beamformed signals from the same network node in the same sector, but these subsequent beamformed signals have different origins because the virtual reference points are changing dynamically. Thus, from the point of view of the device 200, the location of the network node 100 is varying. The device may not trust these positioning reference signals and may refuse them. However, by indicating that the origins indicated in the positioning reference signals may change dynamically, the device 200 may nevertheless trust in these positioning reference signals and may use them for determining its position.

[0101] As described above, in step 702 the network node 100 determines for each beamformed signal 20 to 27 a corresponding positioning information which indicates the respective virtual reference point 40 to 47 determined for the respective beamformed signal 20 to 27. The device 200 may determine its position based on the virtual reference point, a direction information included in the beamformed signal, and the distance between the virtual reference points and the device 200. Instead of basing the distance determination on a virtual timing information included in the beamformed signal, the device 200 may utilize a power with which the beamformed signal is received at the device 200. For example, the network node 100 may transmit at 708 the beamformed signal with a predefined power. The device 200 may determine a path loss by comparing the predefined power used for transmitting the signal at the network node 100 with the power of the beamformed signal as received at the device 200 at 806. Based on the path loss, the device 200 may determine a length of a propagation path of the beamformed signal from the network node 100 to the device 200. As the network node does not include the position of the real origin of the beamformed signal, but the virtual reference point, the network node 100 may adapt the transmit power accordingly or may include a power correction information in the beamformed signal which may be used by the device 200 for correcting the received power such that the determined path loss corresponds to the distance between the virtual reference point and the device 200. A propagation path model may additionally be considered by the device 200 for determining the distance based on the path loss.

[0102] In further examples, the power correction information may comprise an identifier which identifies, in connection with a power correction information mapping, a corresponding power correction value for each beamformed signal. In the power correction information mapping, each beamformed signal may be identified based on the identifier or a resource in which the beamformed signal is transmitted.

[0103] In further examples, a timing correction factor for each beamformed signal may be communicated from the network node 100 to the device 200, for example in connection with the above described message indicating the positioning information (transmitted at 703). Each timing correction factor may be determined by the network node 100 and based on the corresponding offset between the origin 50 and the corresponding virtual transmit point 40 to 47. Instead of transmitting the beamformed signal using the virtual a timing information, the beamformed signal is transmitted using the real timing information at 708. The device 200 receives the beamformed signal at 806 and determines the distance between the device 200 and the virtual transmit point based on the real timing information and the timing correction factor.

[0104] The timing correction information may comprise an identifier which identifies, in connection with a timing correction information mapping, a corresponding timing correction value for each beamformed signal. In the timing correction information mapping, each beamformed signal may be identified based on the identifier or a resource in which the beamformed signal is transmitted.

[0105] For example, at 707 the network node 100 may transmit a message indicating the power correction information mapping or the timing correction information mapping. This message may be transmitted once after the device 200 has registered at the network node 100, in regular terms, upon request from the device 200, upon a change in the mapping or according to any other trigger. The message including the power correction information mapping or the timing correction information mapping may be received by the device at 806 and used by the device at 806 for determining its position.

[0106] FIG. 5 shows a further example for communicating positioning, timing and power related information to the device 200 by involving a location server. The location server may collect information from a network node currently serving the device 200 and may additionally collect information from neighboring network nodes which may also provide beamformed signals which may be processed by the device 200 for positioning purposes. As indicated in FIG. 5, some or all above described messages transmitted at 703 to 707 indicating the positioning information, the indication that the reference signals are based on virtual reference points, the positioning information mapping, the indication that the virtual reference points are changing dynamically, and/or the power or time correction mapping may be transmitted to the location server. The location server receives the corresponding messages at 901 to 905. The location server may collect the above messages from a plurality of network nodes, for example a base station currently serving the device and base stations of neighboring cells. The aforementioned communicating the information (703-707) may involve a positioning protocol signaling between network node(s) and location server, for example the LTE positioning A protocol (LPPa). The collected information may be transmitted at 906 to the device 200 which receives the configuration information at 808. Communicating the information to the device 200 may involve a positioning protocol signaling, for example the LTE positioning protocol (LPP). After being configured with the information received at 808, the network nodes may transmit beamformed signals indicating the corresponding positioning information at 708, and the device 200 may receive the beamformed signals at 806 for determining its position at 807 as described above. Thus, the beamformed signals transmitted at 708 can implement positioning reference signals, e.g., in accordance with a positioning protocol. The beamformed signals may comprise positioning reference signals configured according to the information communicated at 906/808.

[0107] FIG. 6 shows the network node 100 in more detail. The network node 100 may comprise for example an access node of the wireless communication network, for example an eNB of an LTE system or a gNB of a 5G NR system. The network node 100 may comprise control circuitry 101 and a transmitter 102. The network node 100 may comprise more components, in particular for example a receiver, but these components are not shown in the figure for clarity reasons. The network node 100 may comprise furthermore an antenna array 103 comprising a plurality of antenna elements 104. The antenna array 103 may comprise several tens or hundreds of antenna elements 104. The transmitter 102 may be configured to provide radio signals individually to each antenna element 104, for example with an individual phase and an individual power. This may enable the antenna array 103 to transmit beamformed signals as indicated and discussed above in connection with FIG. 2 and FIG. 3. The control circuitry 101 may comprise a controller or digital processor to control the transmitter 102 to transmit beamformed signals as described above in connection with FIG. 4 and FIG. 5 and as described below in connection with FIG. 8.

[0108] FIG. 7 shows the device 200 in more detail. The device 200 may comprise for example a mobile telephone, like smart phone, or an Internet of things (IoT) device. The device 200 may comprise control circuitry 201 and a receiver 202. The device 200 may comprise more components, in particular for example a transmitter and a user interface, but these components are not shown in the figure for clarity reasons. The device 200 may comprise furthermore an antenna 203 for receiving radio signals emitted from the network node 100. The control circuitry 201 may comprise a controller or digital processor configured to determine a position of the device 200 based on downlink signals received from the network node 100 as described above in connection with FIG. 4 and FIG. 5 and as described below in connection with FIG. 9.

[0109] FIG. 8 shows method steps 701 to 708 of a method 700 which may be performed by the network node 100. The method steps in dashed boxes may be considered as optional method steps. The method steps 701 to 708 correspond essentially to the steps and transmissions 701 to 708 described in FIG. 4.

[0110] In step 701, the network node 100 may determine, for each of a plurality of beamformed signals, a virtual reference point. The virtual reference points of the plurality of beamformed signals are offset from a position of a (real) transmit point from which the beamformed signals are transmitted. The transmit point may essentially be the position of the antenna array 103. In particular, each virtual reference point of a corresponding beamformed signal is offset from the position of the real transmit point along the respective transmit direction of the respective beamformed signal. The network node may be configured to transmit the plurality of beamformed signal such that each of the beamformed signals covers a sector in an environment of the network node. In step 702, the network node may determine for each of the plurality of beamformed signals a respective positioning information. The respective positioning information indicates the respective virtual reference point, for example as an absolute or relative geographical coordinate or an identifier or a resource as explained above in connection with FIG. 4. In step 703, the network node may transmit a message indicating the positioning information for each beamformed signal.

[0111] In step 704, the network node 100 may transmit a message indicating that the respective positioning information of the beamformed signals is indicative of a respective virtual reference point. Furthermore, in step 705, the network node may transmit a positioning information mapping which indicates a mapping of the respective positioning information, for example identifiers, to the respective virtual reference point for each of the beamformed signals. Furthermore, in step 706, the network node may transmit a message which indicates that the respective virtual reference points are dynamically changed with subsequent beamformed signals of the same transmit direction. In step 707 the network node may transmit a power correction mapping which indicates a mapping of the respective positioning information to a power correction information for each beamformed signal. The power correction information may be used by the device 200 to determine its position based on a received power of the respective beamformed signal and the power correction information. The power correction information is based on the distance between the virtual reference point and to the position of the transmit point. Additionally or as an alternative, in step 707 of the network node may transmit a time correction mapping which indicates a mapping of the respective positioning information to a time correction information for each beamformed signal.

[0112] Finally, in step 708, the network node 100 transmits at least one beamformed signal of the plurality of beamformed signals. The transmitted beamformed signal indicates the respective positioning information and may additionally indicate a direction information and/or a virtual timing information and/or a power correction information. The direction information indicates a respective transmit direction of the beamformed signal. The virtual timing information is based on the distance between the virtual reference points and the position of the transmit point. For example, the virtual timing information may indicate a transmission start time which does not correspond to the start time of the real transmission, but which is modified by a time duration required for a radio signal to travel from the virtual reference point to the real transmit point. The power correction information is also based on the distance between the virtual reference points and the position of the transmit point. For example, the power correction information may indicate a power loss experienced by a radio signal traveling from the virtual reference points to the real transmit point.

[0113] FIG. 9 shows a method 800 comprising method steps 801 to 807 which may be performed by the device 200. The method steps in dashed boxes may be optional. The method steps 801 to 807 correspond essentially to the steps and transmissions 801 to 807 described in FIG. 4.

[0114] In step 801, the device 200 may receive a message which indicates position information for beamformed signals which may be received and processed by the device 200. In step 802, the device 200 may receive a message which indicates that positioning information received in beamformed signals is indicative of a respective virtual reference point. Additionally or as an alternative, in step 803, the device 200 may receive a positioning information mapping which indicates a mapping of respective positioning information to respective virtual reference points for each of a plurality of beamformed signals. The device 100 may determine the position of the device 100 based on the received beamformed signals and the positioning information mapping. Furthermore, the device 100 may receive in step 804 a message indicating that the respective virtual reference points are dynamically changed with subsequent beamformed signals of a same transmitted direction. This information may also be considered by the device 100 when determining its position. Furthermore, in step 805, the device 100 may receive a power correction mapping which indicates a mapping of respective positioning information to power correction information for each received beamformed signal. The device 100 may use the power correction information retrieved from the power correction mapping when determining the position of the device 100 based on the received power of the respective beamformed signal. Additionally, in step 805, the device 100 may receive a timing correction mapping which indicates a mapping of respective positioning information to timing correction information for each received beamformed signal.

[0115] In step 806 the device 100 receives at least one beamformed signal which is indicative of the respective positioning information. The received beamformed signal may include further information, for example direction information and virtual timing information. In step 807, the device 100 determines, based on the information provided in the beamformed signal, its position additionally considering that the positioning information indicates the respective virtual reference point which is offset from a position of the transmit point from which the beamformed signal is actually transmitted.

[0116] To sum up, the position of the virtual reference point of a beamformed signal is randomly or deterministically selected along the propagation direction of the beamformed signal, in general anywhere along this beam at either side of the receiving device (if the device position is known) or at either side of the antenna array of the network node. This virtual position is broadcasted in each beamformed signal together with direction information and a timestamp (e.g. a start time of transmission). The beamformed positioning reference signal (PRS) is modified as function of a delay value, in which the delay represents the relative position between the virtual reference point and the true/real origin. The time stamp is defined to match the selected virtual position so that the receiving device can use the time stamp to estimate the distance between the device and the selected virtual position (i.e. ToF). If the virtual position is on the opposite side of the device than the antenna array, this time can be negative. The same beam can change the virtual position and the associated timestamp at different time occasions or frequency carriers. As an alternative, the distance between the device and the selected virtual position may be determined based on a power received at the device and a correspondingly provided power correction information.

[0117] The techniques described herein can support UE-based position by allowing the UE to perform both positioning measurements and positioning estimation. The techniques described herein are based on the finding that, generally, positioning estimation can only be performed once the UE knows a location of one or more reference points. In this case, the reference point(s) are the TRP(s)—i.e., transmit point(s)—that transmit positioning reference signal (PRS) for positioning measurement. The UE requires the absolute position of the transmit point(s). The absolute position of the transmit point(s) can be included in a broadcast transmission to all or some of the UEs. Here, it may be possible to limit the broadcast information size (e.g., only one reference point and the rests are the relative position to the reference point.

[0118] Broadcasting the true/absolute transmit point position(s) may expose some issues, particularly security issues.

[0119] According to various examples described herein, to increase security, the absolute position of the transmit point(s) is only transmitted to some UEs, but not all UEs connected to a cellular network. In this case, it could be the UE who request or has required subscriptions. This may limit the usage of UE-based positioning and the benefit is only applicable to some UEs.

[0120] Observation 1: Broadcasting the true position of a transmit point may not be desirable to the network operator and affect the deployment of the UE-based positioning in the real deployment.

[0121] Observation 2: Allowing (e.g., only) some UEs to obtain the true position(s) of transmit points may limit the usage of UE-based positioning.

[0122] According to the techniques described above, UE-based positioning can be supported without exposing the true reference point of the transmit point. This is based on virtual reference points provided to one or more UEs for the positioning estimation purpose. Virtual reference points can define a virtual position, i.e., a position with a relative non-disclosed distance from the true position.

[0123] Proposal 1: Support UE-based positioning by informing the UE of (e.g. unicast/broadcast) a virtual position of a transmit point associated with each beam.

[0124] As the true reference point(s) position is not to be used, the TRP needs to convey the relative distance information to the UE. It is possible to manipulate the PRS so that it behaves as if it originated from the virtual TRP position. This can be implemented in a transparent manner from a UE perspective.

[0125] Proposal 2: The usage of virtual reference point position for each beam can be supported by conveying the relative distance information in the PRS signal transparent to the UE algorithm.

[0126] In this document above, a Virtual Reference point is introduced, in order to not disclose the true TRP or base station location.