WO2024141150A1 - Ue positioning based on reference signal received power - Google Patents

Abstract

A received signal power difference corresponds to a beamforming gain difference between two overlapping beams reported by a device. By exploiting the beam pattern knowledge related to the beamforming gains of the two selected overlapping beams, the direction of arrival of the device can be estimated by mapping the beamforming gain difference corresponding to the received signal power difference to at least one direction of arrival..

Description

DESCRIPTION UE POSITIONING BASED ON REFERENCE SIGNAL RECEIVED POWER TECHNICAL FIELD [0001] Various example embodiments relate generally to methods and apparatus for UE positioning. BACKGROUND [0002] The present disclosure is for example applicable to a telecommunication system such as a 5G (fifth generation) network using the 5G NR (New Radio) as radio access technology (RAT) defined by 3GPP. [0003] In Release 16, the positioning work has been conducted in 3GPP for native NR positioning and solutions based on timing advance (TA) or Angle-of-Arrival (AoA) estimation have been proposed. As NR is a beam-based access system using beamforming procedure, usually a beam is first selected for the UE and then the positioning reference signal (e.g. SRS, Sounding reference signal, for UL and PRS, Positioning Reference Signal, for DL) is transmitted to the UE using the selected beam. Using the reference signal, the timing advance or AoA of the UE can be estimated. Then positioning methods, such as cross-bearing, may be applied to determine the position of the UE. [0004] These standardized solutions constitute a procedure of two steps: the first step is to find a good beam to carry the reference signal and the second step is to use the reference signal to estimate UE’s position. Because the second step depends on the first step, finding a good beam is crucial to the positioning accuracy. This raises the problem of finding the good beam, which triggers the need for further enhancement for beam management, e.g., beam acquisition and beam failure recovery. On the other hand, to improve the beam management performance, methods using UE’s position information to select the best beam have been proposed. Therefore, the UE positioning and beam management problems are inextricably linked (“chicken-egg problem”). [0005] Another issue for the standardized solutions is the high memory and high computational complexity or associated costs. [0006] In this context, time-difference based positioning methods have been proposed for low-cost devices (e.g. Reduced Capability, RedCap, UEs) such TDoA (Time Difference of Arrival) but these methods fail to provide sufficient multipath resolution due to very limited PRS/SRS bandwidth supported by these low-cost devices and these time difference-based methods for localizing low cost devices suffer from lack of timing resolution in narrow band devices. [0007] There is also a need for UE positioning methods for which the accuracy is improved with zero extra signaling or radio resource overhead. SUMMARY [0008] The scope of protection is set out by the independent claims. The embodiments, examples and features, if any, described in this specification that do not fall under the scope of the protection are to be interpreted as examples useful for understanding the various embodiments or examples that fall under the scope of protection. [0009] According to a first aspect, a method comprises: obtaining a mapping function mapping beamforming gain differences and pairs of beam indexes with directions of arrival defined with respect to a first device, wherein a pair of beam indexes consists of indexes identifying two distinct and overlapping beams sent by the first device during beam sweeping procedure; obtaining a first respectively second beam index identifying a first respectively second beam reported by a second device during a beam reporting procedure, where the second beam overlaps the first beam; obtaining a first received signal power difference computed based on a first received signal power measured by the second device for the first beam and a second received signal power measured by the second device for the second beam; determining a direction of arrival of the second device with respect to the first device based on at least a first direction of arrival obtained by applying the mapping function to a beamforming gain difference corresponding to the first received signal power difference and the pair of beam indexes consisting of the first and second beam indexes. [0010] The first beam may be the best beam reported by the second device in a first set of beams and the second beam may be the best beam reported by the second device in a second set of beams. [0011] A beamforming gain difference and a pair of beam indexes may be mapped with at least two directions of arrival. A beamforming gain difference and a pair of beam indexes may be mapped with one direction of arrival. [0012] At least one of the first received signal power and the second received signal power may be a Reference Signal Received Power, RSRP. [0013] The mapping function may be implemented by a look-up table. [0014] The mapping may be based on the beamforming patterns used for beams in the first and second sets of beams, where the beamforming patterns defines beamforming gains in a plurality of directions used for beams. [0015] A direction of arrival may be mapped with a beamforming gain difference and a given pair of beam indexes when the difference between the beamforming gains used in the direction of arrival for the two beams identified by the concerned pair of beam indexes is equal to the beamforming gain difference. [0016] The method may comprise: obtaining a third beam index identifying a third beam reported by a second device; determining a second direction of arrival of the second device with respect to the first device by applying the mapping function to a beamforming gain difference corresponding to the first received signal power difference and the pair of beam indexes consisting of the first and second beam indexes; selecting one of the first and second directions of arrival on the basis of the third beam index, wherein the selected direction of arrival corresponds to a direction that is closer to the boresight direction of the third beam. [0017] The third beam may be the second best beam reported by the second device in the first or second set of beams. [0018] The method may comprise: obtaining a second received signal power difference computed based on the first received signal power and a third received signal power measured by the second device for the third beam; determining a third direction of arrival of the second device with respect to the first device by applying the mapping function to a beamforming gain difference corresponding to the second received signal power difference and the pair of beam indexes consisting of the first and third beam indexes; selecting as the direction of arrival of the second device with respect to the first device, one of the first and second directions of arrival of the second device that is the closest to the third direction of arrival. [0019] The first device may be a base station and the second device may be a user equipment or vice versa. [0020] The method may comprise: reporting the direction of arrival of the second device with respect to the first device by a user equipment to a base station or by a base station to a Location Management Function or by a Location Management Function to a base station or by a base station to a user equipment. [0021] The method may comprise: receiving at least one of the mapping function, the first and second beam indexes and the first and second received signal power by a Location Management Function from a user equipment or from a base station. [0022] The method may comprise: receiving at least one of the mapping function, the first and second beam indexes and the first and second received signal power by a user equipment from a base station. [0023] The method may comprise: receiving at least one of the mapping function, the first and second beam indexes and the first and second received signal power by a base station from a user equipment by a Location Management Function or by a base station. [0024] According to another aspect, an apparatus comprises means for performing a method comprising: obtaining a mapping function mapping beamforming gain differences and pairs of beam indexes with directions of arrival defined with respect to a first device, wherein a pair of beam indexes consists of indexes identifying two distinct and overlapping beams sent by the first device during beam sweeping procedure; obtaining a first respectively second beam index identifying a first respectively second beam reported by a second device during a beam reporting procedure, where the second beam overlaps the first beam; obtaining a first received signal power difference computed based on a first received signal power measured by the second device for the first beam and a second received signal power measured by the second device for the second beam; determining a direction of arrival of the second device with respect to the first device based on at least a first direction of arrival obtained by applying the mapping function to a beamforming gain difference corresponding to the first received signal power difference and the pair of beam indexes consisting of the first and second beam indexes. [0025] The apparatus may comprise means for performing one or more or all steps of the method according to the first aspect. The means may include circuitry configured to perform one or more or all steps of a method according to the first aspect. The means may include at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform one or more or all steps of a method according to the first aspect. [0026] According to another aspect, an apparatus comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform: obtaining a mapping function mapping beamforming gain differences and pairs of beam indexes with directions of arrival defined with respect to a first device, wherein a pair of beam indexes consists of indexes identifying two distinct and overlapping beams sent by the first device during beam sweeping procedure; obtaining a first respectively second beam index identifying a first respectively second beam reported by a second device during a beam reporting procedure, where the second beam overlaps the first beam; obtaining a first received signal power difference computed based on a first received signal power measured by the second device for the first beam and a second received signal power measured by the second device for the second beam; determining a direction of arrival of the second device with respect to the first device based on at least a first direction of arrival obtained by applying the mapping function to a beamforming gain difference corresponding to the first received signal power difference and the pair of beam indexes consisting of the first and second beam indexes. [0027] The instructions, when executed by the at least one processor, may cause the apparatus to perform one or more or all steps of a method according to the first aspect. [0028] According to another aspect, a computer program comprises instructions that, when executed by an apparatus, cause the apparatus to perform: obtaining a mapping function mapping beamforming gain differences and pairs of beam indexes with directions of arrival defined with respect to a first device, wherein a pair of beam indexes consists of indexes identifying two distinct and overlapping beams sent by the first device during beam sweeping procedure; obtaining a first respectively second beam index identifying a first respectively second beam reported by a second device during a beam reporting procedure, where the second beam overlaps the first beam; obtaining a first received signal power difference computed based on a first received signal power measured by the second device for the first beam and a second received signal power measured by the second device for the second beam; determining a direction of arrival of the second device with respect to the first device based on at least a first direction of arrival obtained by applying the mapping function to a beamforming gain difference corresponding to the first received signal power difference and the pair of beam indexes consisting of the first and second beam indexes. [0029] The instructions may cause the apparatus to perform one or more or all steps of a method according to the first aspect. [0030] According to another aspect, a non-transitory computer readable medium comprises program instructions stored thereon for causing an apparatus to perform at least the following: obtaining a mapping function mapping beamforming gain differences and pairs of beam indexes with directions of arrival defined with respect to a first device, wherein a pair of beam indexes consists of indexes identifying two distinct and overlapping beams sent by the first device during beam sweeping procedure; obtaining a first respectively second beam index identifying a first respectively second beam reported by a second device during a beam reporting procedure, where the second beam overlaps the first beam; obtaining a first received signal power difference computed based on a first received signal power measured by the second device for the first beam and a second received signal power measured by the second device for the second beam; determining a direction of arrival of the second device with respect to the first device based on at least a first direction of arrival obtained by applying the mapping function to a beamforming gain difference corresponding to the first received signal power difference and the pair of beam indexes consisting of the first and second beam indexes. [0031] The program instructions may cause the apparatus to perform one or more or all steps of a method according to the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS [0032] Example embodiments will become more fully understood from the detailed description given herein below and the accompanying drawings, which are given by way of illustration only and thus are not limiting of this disclosure. [0033] FIG.1 illustrates principles of a positioning method according to an example. [0034] FIG.2 illustrates aspects of a positioning method according to an example. [0035] FIG.3 is a flow diagram of a positioning method according to an example. [0036] FIGS.4A-4B show flow diagrams illustrating aspects of a positioning method according to examples. [0037] FIGS.5A-5B illustrate aspects of the proposed positioning method according to examples. [0038] FIG.6 is a block diagram illustrating an exemplary hardware structure of an apparatus according to an example. [0039] It should be noted that these drawings are intended to illustrate various aspects of devices, methods and structures used in example embodiments described herein. The use of similar or identical reference numbers in the various drawings is intended to indicate the presence of a similar or identical element or feature. DETAILED DESCRIPTION [0040] Detailed example embodiments are disclosed herein. However, specific structural and/or functional details disclosed herein are merely representative for purposes of describing example embodiments and providing a clear understanding of the underlying principles. However, these example embodiments may be practiced without these specific details. These example embodiments may be embodied in many alternate forms, with various modifications, and should not be construed as limited to only the embodiments set forth herein. In addition, the figures and descriptions may have been simplified to illustrate elements and / or aspects that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, many other elements that may be well known in the art or not relevant for the understanding of the invention. [0041] An angle-based method to position a device using passive sensing is disclosed herein. The method does not need the two steps positioning procedure presented in introduction. The method does not need to trigger any extra reference signals, so even PRS (Positioning Reference Signal) is not needed. The proposed method only utilizes the existing beam(s) reporting defined in the current standard. As a consequence, the proposed method provides a basic sensing service for UE positioning with no standard modification, requiring negligible costs and resources to implement, that decorrelates the positioning problem from the beam management problem and without the bandwidth related drawbacks of the low-cost devices. [0042] The method can be implemented in the existing standardized networks such as 5G NR and the forthcoming 5G Advanced. Further improvement in UE positioning accuracy could be achieved by incorporating very light changes to standard, making it suitable to also provide standard impact potential for future 6G networks. [0043] The positioning method allows to estimate the Direction of Arrival (DoA) of a device (e.g. a UE). The positioning method may be based on the two-level beam reporting procedure specified in the 3GPP standard (see e.g.3GPP TS 37.355, TS 38.305). [0044] Takings as example the UE positioning by an access node that receives the UE beam reporting, beam indexes and the associated received signal power values (e.g. RSRP, Reference Signal Received Power, in a 3GPP context) measured by the UE for any two overlapping beams reported by the UE for the two levels, the received signal power difference between the two overlapping beams can be calculated for the UE. This received signal power difference corresponds to a beamforming gain difference between the two overlapping beams. Then, exploiting the beam pattern knowledge related to the beamforming gains of the two selected overlapping beams, the DoA of the device can be estimated by mapping the beamforming gain difference corresponding to the received signal power difference to at least one DoA with respect to the base station, e.g. the boresight of the antenna panel of the base station. [0045] The principles disclosed herein are applicable to 2D beamforming 3D beamforming scenario. The principles disclosed herein are applicable to estimation by a base station of a DoA of a UE or to estimation by a UE of a DoA of a base station. The principles disclosed herein are applicable for received signal power difference, that may be computed for example based on RSRP values reported by a UE or any other received signal power values measured by a device. [0046] FIG.1 illustrates aspects of the positioning method in the example case with a UE 100 and a base station 110. [0047] FIG.1 illustrates the positioning method with a 2D beamforming procedure but the positioning method is likewise applicable to 3D beamforming procedure. [0048] In the two-level beam reporting procedure specified in current 3GPP standard, the UE 100 first reports to the base station 110 a first beam index from a first set of beams (e.g. a set of fat beams) and then, within the coverage of the selected fat beam, a second beam index from a second set of beams (e.g. a set of thin beams). [0049] Note here that the two selected beams, the first fat beam 151 and the second thin beam 152, are overlapping but with different spatial patterns as illustrated by FIG.1. The terms “fat and thin beams” are used herein to facilitate the distinction between the two sets of beams and the two selected beam but the terms “wide and narrow beams” may equivalently be used. The positioning method disclosed herein works for any arbitrary beam grid deployment (e.g. any beam spacing and directivity for the cell). In addition, the positioning accuracy does not depend on beam granularity. As long as the beam grid is fixed and deployed in a cell, the proposed method can estimate the DoA of UE with improved accuracy based on a received signal power difference (for example a RSRP difference) for two overlapping beams. [0050] The positioning method disclosed herein focuses on the LoS (Line-of-Sight) cases where a dominant direct path exists. For the NLoS (Non-Line-of-Sight) cases the beam or the reference signal over the beam bounces and redirects at the reflectors, which creates multiple images of the target and blurs its real position, making it a more challenging task to be handled by more advanced sensing/localization methods. [0051] As shown in Figure 1, the beam 151 is the first selected beam (e.g. fat beam) identified by index ^^^_^^^ from a first level of beam reporting and the RSRP value reported by the UE for this first selected beam is ^^^^_^^^. The beam 152 is the second selected beam (e.g. thin beam) by index ^^^_^^^^ from a second level of beam reporting and the RSRP value reported by the UE for this second selected beam is ^^^^_^^^^. [0052] A pair (^^^_^, ^^^^_^) represents herein information of a beam report, the pair including a reported beam index ^^^_^ and a corresponding reported RSRP value ^^^^_^. Let ^ represent the DoA of the UE, then ^_^^^ ⁽^⁾ and ^_^^^^ ⁽^⁾ represent the beamforming gain (e.g. in dB scale) in direction of ^ for the selected fat beam and the selected thin beam respectively. The dots 161 and 162 represented in FIG.1 correspond to a spatial positions for which the beamforming gain are known for the DoA corresponding to the angle ^. [0053] The corresponding reported RSRP values (in dB scale) are such that

where ^^ (in dB scale) is a common term that accounts for the pathloss along a path between the access node 120 and the UE 110, including all losses of transmit power, transmit antenna gain, and other related losses and gains due to the radio channel between the access node 120 and the UE 110. The path loss depends on the radio channel between the access node 120 and the UE 110 but is independent of the beamforming gains. Then the RSRP difference is such that: ^^^^_^^^ - ^^^^_^^^^ = ^_^^^ ⁽^⁾ - ^_^^^^ ⁽^⁾ [0054] This means this RSRP difference corresponds (e.g. is equal) to the beamforming gain difference for ^ between the selected fat beam ^^^_^^^ and the selected thin beam ^^^_^^^^. [0055] Also because the beam patterns - and especially the beamforming gains with respect to the directions covered by a beam - are known by access node (e.g. this is a priori knowledge once the beam grid deployment is done) and the beamforming gain difference between the two beams with different beam width is different for different ^ values, the beamforming gain difference can be used to determine the angle ^, i.e. the DoA of the UE. [0056] As a consequence, the RSRP difference between two reported beams corresponds to a beamforming gain difference between the two reported beams, and the RSRP difference can be used to calculate the DoA of the UE, knowing the beam patterns. This property can be expressed by defining a mapping function ^ that maps a DoA with a RSRP difference (or likewise a beamforming gain difference) and a given pair of beam indexes (^^^_^, ^^^_^). For example: ^ = ^( ^^^^_^^^ − ^^^^_^^^^) = ^(^_^^^ ⁽^⁾ − ^_^^^^ ⁽^⁾) = ^(^_^^^^(^))

represents the beamforming gain difference, as a function of ^ for the two selected beams. [0057] In one or more embodiments with low implementation complexity, a loop-up function is used for implementing the mapping function of the RSRP difference with the DoA ^. Other embodiments, such as curve fitting, may also be used but with an expense of complexity. Here, we provide an example of the lookup table based implementation embodiment. [0058] As an example, we assume that there are in total 4 fat beams X_^^^ (X=1 to 4) in a first set of beams and 16 thin beams X_^^^^ (X=1 to 16) in a second set of beam. The overlapping beams of the first and second sets of beams are associated, for example in the way defined below: 1_^^^ → 1_^^^^, 2_^^^^, 3_^^^^, 4_^^^^, 2_^^^ → 5_^^^^, 6_^^^^, 7_^^^^, 8_^^^^, 3_^^^ → 9_^^^^, 10_^^^^, 11_^^^^, 12_^^^^,

where the association

^_^^^^ means that the ^^{^^} thin beam is overlapping with the ^^{^^} fat beam in the beam grid deployment, that is, the main lobe of the thin beam is intersecting with the main lope of the fat beam. Then the look up table that maps beamforming gain difference values with DoA value can be implement as shown: 1_^^^ 2_^^^ …. ^_^^^^ ⁽ _^ ⁾ 1_^^^^ 2_^^^^ 3_^^^^ 4_^^^^ 5_^^^^ 6_^^^^ 7_^^^^ 8_^^^^ …. (dB) Y1 …. ⋮ …. YN …. [0059] The number of rows of the table and the mapped ^ values depend on the beam grid deployed for a radio cell and may be fixed once the beam grid is fixed. The number of rows corresponds to a number of sampled beamforming gain difference values Y₁ to Y_N and has an impact on the accuracy with which the mapping is done. [0060] For a given RSRP difference computed based on RSRP values reported by a device, a corresponding beamforming gain difference is searched in the lookup table. Since there may be no beamforming gain difference that is equal to the RSRP difference: the closest beamforming gain difference may be used to find the DoA mapped with the RSRP difference or an interpolation be performed on the DoA mapped with the two or more closest beamforming gain differences to compute the DoA mapped with the current RSRP difference. [0061] FIG.2 illustrate the DoA estimation ambiguity resulting from symmetric beam pattern. [0062] It is noted that in this example, due to symmetric beam patterns, estimation ambiguity may exist when two or more DoAs can be mapped to one beamforming gain difference value by a mapping function. As shown in FIG.2, the curve 200 represent the beamforming gain difference as a function of the DoA ^ between a selected fat beam and a selected thin beam. In this example, two angles

and ^_^ can be mapped to the same beamforming gain difference value. [0063] For solving this ambiguity, multiple beam reporting can be configured and used for the UE. When the UE is configured with multiple beam reporting, the UE measures RSRP for all beams and select several best N (N>1) beams to report. In FIG.2, the best fat beam is B2 and the best thin beam is B11. If the second best thin beam for the UE is the left one B12, then the DoA should be

that is that is closer to the boresight direction ^_^^ of second best beam B12. Likewise, if the second best thin beam is the right one B13 then the DoA should be ^_^ that is closer to the boresight direction of the beam B13. [0064] A direction that closer to the boresight direction of a beam may be determined based on angle values. In one dimension, it is based on the absolute value of the difference between two angles, e.g. ^|^_^^ − ^_^ ^| or ^|^_^^ −

In two-dimension case (both azimuth and elevation), it is based on the angle difference between the two directions (candidate direction and the boresight direction). [0065] Another way to solve the ambiguity is to explore UE’s beam reporting history. For example, if in FIG.2, the UE reports the left thin beam B12 at least once as the best beam in history though most of the time the UE reports the beam B11 as the best, then the that is closer to the boresight direction of the beam B12 in the history should be the DoA of the UE as the reporting history never include the beam B13 whose boresight direction is closer to the other angle ^_^. [0066] To solve the ambiguity problem, multiple (more than two) beam reports for overlapping beams may be used to narrow down the angle range of the UE position, therefore improving the DoA estimation accuracy. Besides, exploring the symmetricity of the beams (so the angle range is halfed) or using a thin-thin overlapping beam pair instead of a fat-thin overlapping beam pair can be used to improve the accuracy. [0067] FIG.3 is a flowchart illustrating a position method according to an example. The steps of the method may be implemented by a host apparatus, e.g. a UE, gNB or LMF according to any example described herein. [0068] In the below description, the first device may be a base station (e.g. gNB) or LMF and the second device may be a user equipment or vice versa. [0069] While the steps are described in a sequential manner, the man skilled in the art will appreciate that some steps may be omitted, combined, performed in different order and / or in parallel. [0070] In step 310, a mapping function mapping beamforming gain differences and pairs of beam indexes with directions of arrival defined with respect to a first device is obtained. A pair of beam indexes consists of indexes identifying two distinct and overlapping beams sent by the first device during beam sweeping procedure. [0071] A beamforming gain difference and a pair of beam indexes may be mapped with at least two directions of arrival. A beamforming gain difference and a pair of beam indexes may be mapped with (only) one direction of arrival. [0072] The mapping function may be implemented by a look-up table. [0073] The mapping may be based on the beamforming patterns used for beams in the first and second sets of beams, where the beamforming patterns defines beamforming gains in a plurality of directions used for beams. A direction of arrival may be mapped with a beamforming gain difference and a given pair of beam indexes when the difference between the beamforming gains used in the direction of arrival for the two beams identified by the concerned pair of beam indexes is equal to the beamforming gain difference. [0074] In step 320, a first respectively second beam index identifying a first respectively second beam reported by a second device during a beam reporting procedure are obtained. The second beam overlaps the first beam. [0075] The first beam may be the best beam reported by the second device in a first set of beams and the second beam may be the best beam reported by the second device in a second set of beams. [0076] In step 330, a first received signal power difference computed based on a first received signal power measured by the second device for the first beam and a second received signal power measured by the second device for the second beam is obtained. [0077] In step 340, a direction of arrival of the second device with respect to the first device is determined based on at least a first direction of arrival obtained by applying the mapping function to a beamforming gain difference corresponding to the first received signal power difference and the pair of beam indexes consisting of the first and second beam indexes. [0078] In step 340, in case of ambiguity for determining the direction of arrival, for example when a beamforming gain difference and a pair of beam indexes is mapped with at least two directions of arrival, further steps may be used. [0079] A a third beam index identifying a third beam reported by a second device may be obtained. The third beam may for example be the second best beam reported by the second device in the first or second set of beams. [0080] A second direction of arrival of the second device with respect to the first device may be determined by applying the mapping function to a beamforming gain difference corresponding to the first received signal power difference and the pair of beam indexes consisting of the first and second beam indexes. [0081] Then the ambiguity may be solved by selecting one of the first and second directions of arrival on the basis of the third beam index, wherein the selected direction of arrival corresponds to a direction that is closer to the boresight direction of the third beam. [0082] In one or more embodiments, the ambiguity may be solved by using the available mapping as follows. A second received signal power difference computed based on the first received signal power and a third received signal power measured by the second device for the third beam is obtained. Then a third direction of arrival of the second device with respect to the first device is determined by applying the mapping function to a beamforming gain difference corresponding to the second received signal power difference and the pair of beam indexes consisting of the first and third beam indexes. The ambiguity may be solved by selecting as the direction of arrival of the second device with respect to the first device, one of the first and second directions of arrival of the second device that is the closest to the third direction of arrival. [0083] The proposed positioning method can be implemented for the positioning of any device for which at least two beam reports with beam indexes and received signal power measured values are available. It may be applied not only to UE positioning but also to access nodes or base station positioning, e.g. for gNB positioning. The DoA may be determined for a base station with respect to a user equipment or vice-versa. The determination of the DoA may be performed by the base station, by the UE, or by a third device. Further, the mapping function may be determined for a device by the concerned device or another device on the basis of the beam patterns used by the concerned device. The measured received signal power values may be, for measurements performed by UE, RSRP, Reference Signal Received Power, values. [0084] Further, the DoA determined by a device may be reported to another device. For example, the DoA may be reported by a base station to a Management Function (LMF) and / or by a LMF to a base station and / or by a base station to a user equipment. [0085] Likewise, the mapping function (or beam patterns) may be determined by a device and be reported to another device that is configured to perform the determination of the DoA. The device that is configured to perform the determination of the DoA may be configured to obtain at least one of the mapping function, the beam indexes of the overlapping beams and the measured received signal power values. [0086] At least one of the mapping function, the beam indexes of the overlapping beams and the measured received signal power values may be received by a LMF from a user equipment or by a LMF from a base station. At least one of the mapping function, the beam indexes of the overlapping beams and the measured received signal power values may be received by a user equipment from a base station. At least one of the mapping function, the beam indexes of the overlapping beams and the measured received signal power values may be received by a base station from a user equipment by a LMF and/or by a base station. [0087] An access node may be any type of base station (eNB, gNB, gNB-DU, gNB- CU, etc). At least part of the functionalities of the access node may also be carried out by a network device (like a network node, a server, a host device, a host system) which is operably coupled to a transceiver (such as a remote radio head for example) and which may include other functions (such as an OAM function or another network function that may be used for implementing features in a NWDAF, Network Data Analytics Function, etc). [0088] A user equipment, UE, (or user terminal, user device) may refer to a computing device that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (MS), a mobile phone, a radio cell phone, a smartphone, a personal digital assistant (PDA), a handset, a device using a wireless modem (alarm or measurement device, etc.), a laptop and/or touch screen computer, a tablet, a phablet, a game console, a notebook, and a multimedia device, as examples. [0089] Depending on the involved devices, several signaling scenarios may be used. Several example use cases are described by reference to FIGS.4A and 4B. [0090] FIG.4A shows a flowchart of a method for a first use case according to one or more example embodiments. While the steps are described in a sequential manner, the man skilled in the art will appreciate that some steps may be omitted, combined, performed in different order and / or in parallel. [0091] The steps involve a UE, a base station (e.g. gNB), a LMF and LCS (Location Service). [0092] In steps 410-415, positioning set up is performed. [0093] In step 410, a Location Service Request is sent from a LCS to a LMF. [0094] In step 411, the LMF sends to the UE a request for capabilities concerning the capability of the UE in supporting localization and positioning service. For example, how much bandwidth the UE could support. [0095] In step 412, in response the UE sends to the LMF its capabilities. [0096] In step 413, the UE sends to the LMF a request for assistance data [0097] In step 415, Positioning Reference Signal configuration is performed between the UE, the gNB and the LMF. [0098] In steps 416-418, beam measurements are performed for DL positioning of the UE. [0099] In step 416, the gNB sends first fat beams. A first fat beam is received by the UE. [00100] In step 417, the gNB sends second thin beams. A second fat beam is received by the UE. [00101] In step 418, the UE performs RSRP measurements on the first fat beam and the second thin beam and reports the measurements to at least one or the gNB and the LMF. The LMF and / or gNB may be configured to determine the DoA of the UE using a mapping function (e.g. a mapping table). [00102] FIG.4B shows a flowchart of corresponding to other use cases according to one or more example embodiments. The steps involve a UE, a base station (e.g. gNB) and a LMF. [00103] For downlink positioning of a UE (in a UE assisted case corresponding to case #1 in FIG. 4B), the beam report, the beam indexes and the associated RSRP difference may be reported (step 421, e.g. using LPP) from UE to LMF. The LMF may be configured to determine the DoA of the UE using a mapping function (e.g. a mapping table). Here the gNB’s beam patterns may be signaled by the gNB to LMF to allow the LMF to generate the mapping function or the mapping function may be signaled by the gNB to LMF. [00104] In another embodiment for downlink positioning of a UE (in a UE based case corresponding to case #2 in FIG. 4B), the beam report, the beam indexes and the associated RSRP difference are not reported from UE to LMF, but the mapping function and/ or beam patterns and RSRP information allowing the determination of the mapping function are signaled (step 422, e.g. using LPP) from LMF to UE. The UE may be configured to determine the DoA based on the mapping function and report (step 423, e.g. using LPP) the DoA to the LMF. Here the gNB’s beam patterns may be signaled by the gNB to LMF to allow the LMF to generate the mapping function or the mapping function may be signaled by the gNB to LMF. [00105] In another embodiment for downlink positioning of a UE (suitable for UEs in RRC_INACTIVE state) in a UE assisted case corresponding to case #3 in FIG. 4B, the beam report, the beam indexes and the associated RSRP difference may be reported (step 424, e.g. using RRC) from UE to gNB and then reported (step 425, e.g. using NRPPa) from gNB to LMF. The LMF may be configured to determine the DoA of the UE using a mapping function. Here the gNB’s beam patterns may be signaled by the gNB to LMF to allow the LMF to generate the mapping function or the mapping function may be signaled by the gNB to LMF. [00106] In another embodiment for downlink positioning in a UE based case corresponding to case #4 in FIG.4B, the beam report, the beam indexes and the associated RSRP difference are not reported from UE to gNB. The mapping function and/or beam patterns and RSRP information allowing the determination of the mapping function may be signaled from LMF to gNB (step 426, e.g. using NRPPa) and from gNB to UE (step 427, e.g. using RRC). The UE may then be configured to determine the DoA and report the DoA to gNB (step 428, e.g. using RRC) and from gNB to the LMF (step 429, e.g. using NRPPa). Here the gNB’s beam patterns may be signaled by the gNB to LMF. [00107] For two levels beam reporting downlink positioning of a UE, the LMF may configure either directly the UE or the UE via gNB the two level beam reporting in order to measure at least two overlapping beams. This could be done by configuring and triggering separate semi-persistent or aperiodic DL CSI-RS (PRS) or leveraging the existing beam reporting procedure via SSB or periodic DL CSI-RS measurement. [00108] For uplink positioning of gNB with respect to a UE, a gNB may perform received signal power measurements for received repeated SRS for two overlapping beams received from UE. The gNB may report the beam indexes and the associated received signal power difference to the LMF. A mapping function between the beamforming gain difference and DoA or the gNB’s beam patterns may be signaled from gNB to LMF. The LMF may be configured to determine the DoA of the gNB with respect to a UE using a mapping function stored by the LMF (e.g. either the mapping function received from the gNB or a mapping function determined by the LMF based on the beam patterns signaled by the gNB). The advantage in this UL implementation is the decoupling of positioning procedure from beam reporting procedure, which minimizes the standard specification effort. [00109] For uplink positioning of gNB with respect to a UE, the LMF may configure either directly the UE or the UE via gNB to send repeated UL SRS. This could be done by configuring and triggering separate semi-persistent or aperiodic SRS or leveraging the existing beam management procedure via periodic SRS transmission. [00110] The accuracy of the method can be evaluated in various manners. [00111] Suppose that we have a 120 degree cell for the angle range, and in current standard the SSB based RSRP report is within a range from -140 dBm to -40 dBm with 1dB resolution. Simple calculation leads us to 1.2 degree resolution for the DoA estimation based on the proposed method, i.e.1dB RSRP difference is mapped to 1.2 degree of angle difference, assuming a linear dependency between the DoA and the RSRP difference. [00112] In 3GPP TS 38.133 (see Table 10.1.2.1.1-1), the SSB-RSRP intra frequency absolute accuracy in FR1 (Frequency range 1 as defined in clause 5.1 of TS 38.104), normal condition, is of ±4.5 dB: in such case the accuracy of the proposed positioning method is around ±5 degree. Thus the accuracy of the proposed positioning method depends on accuracy of the UE measurement for RSRP reporting. [00113] FIGS. 5A-5B illustrate the resolution and accuracy of the proposed positioning method in an example embodiment with fat and thin beams. [00114] The beamforming gain of the beam patterns of the two beams (which can be used to calculate the RSRP difference) as a function of the beam angle of arrival/departure are plotted for two different positions of the UE corresponding to two DoAs. All angles here are defined with respect to the boresight direction of the array. The main beams of beam 51 and 52 point to the 0-degre direction (the boresight direction of the array) whereas the main beam of beam 53 points to the 10-degre direction. As shown in FIGS. 5A-5B, the beamforming gain of a fat beam using 4-element ULA (Uniform Linear Array) antenna array points to its boresight as a function of the angle of arrival/departure (curves 51 of FIGS.5A- 5B), and the beamforming gain of a thin beam using the 16-element ULA points as a function of the angle of arrival/departure at 0 degree (curve 52 of FIG.5A) and at 10 degrees respectively (curve 53 of FIG.5B) are shown. [00115] Beam grid optimization will guarantee that if a beam is selected by a UE, the UE will reside in the main lobe of the beam. So one can consider only the RSRP difference between the two main lobes of the fat beam and the thin beam. As can be seen from FIGS. 5A-5B that either for the 0 degree or the 10 degrees thin beam case, the RSRP difference of 20 dB range can be mapped to around 10 degree of angle range. Thus the resolution is actually around 0.5 degree per 1dB RSRP difference. With a ±4.5 dB RSRP measurement error, the accuracy of the proposed positioning method will be around ±2 degree. [00116] The proposed positioning method can be seen as pseudo passive sensing, without introducing any extra reference signal overhead or control signaling overhead. The proposed positioning method can position the UE with high accuracy. [00117] The proposed positioning method explores the hidden sensing capability in the network, without any standard modification, and can provide sensing service for the positioning use case. [00118] The proposed positioning method can be implemented with very low complexity, e.g. a look up table is sufficient. Besides, the proposed method does not require high bandwidth of dedicated positioning reference signal transmission since the angular methods (DoA) are able to operate at narrower bandwidth than time based methods (ToA). Therefore, it could also be applied to the low cost devices, e.g. RedCap UEs. [00119] The proposed positioning method can be implemented in a framework with beam reports based on one or more reference signals or a combination of reference signals (e. g. CSI-RS, Channel State Information Reference Signal (PRS), SSB and SRS). [00120] The proposed positioning method may be implemented for radio telecommunication systems, including a fifth generation (5G) network or 6G network. It is applicable to prior or subsequent generations of radio telecommunication systems where analog beamforming is used. The positioning method disclosed herein could be implemented for example in 5G and 5G Advanced base stations at mm-wave band where large phase array with grid-of-beam implementation. The positioning method disclosed herein may also be implemented in RFIC/beam-control module to improve their DoA estimation accuracy. [00121] It should be appreciated by those skilled in the art that any functions, engines, block diagrams, flow diagrams, state transition diagrams, flowchart and / or data structures described herein represent conceptual views of illustrative circuitry embodying the principles of the invention. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes. [00122] Although a flow chart may describe operations as a sequential process, many of the operations may be performed in parallel, concurrently or simultaneously. Also some operations may be omitted, combined or performed in different order. A process may be terminated when its operations are completed but may also have additional steps not disclosed in the figure or description. A process may correspond to a method, function, procedure, subroutine, subprogram, etc. When a process corresponds to a function, its termination may correspond to a return of the function to the calling function or the main function. [00123] Each described function, engine, block, step described herein can be implemented in hardware, software, firmware, middleware, microcode, or any suitable combination thereof. [00124] When implemented in software, firmware, middleware or microcode, instructions to perform the necessary tasks may be stored in a computer readable medium that may be or not included in a host apparatus or host system. The instructions may be transmitted over the computer-readable medium and be loaded onto the host apparatus or host system. The instructions are configured to cause the host apparatus or host system to perform one or more functions disclosed herein. For example, as mentioned above, according to one or more examples, at least one memory may include or store instructions, the at least one memory and the instructions may be configured to, with at least one processor, cause the host apparatus or host system to perform the one or more functions. Additionally, the processor, memory and instructions, serve as means for providing or causing performance by the host apparatus or host system of one or more functions disclosed herein. [00125] The host apparatus or host system may be a general-purpose computer and / or computing system, a special purpose computer and / or computing system, a programmable processing apparatus and / or system, a machine, etc. The host apparatus or host system may be or include or be part of: a user equipment, client device, mobile phone, laptop, computer, network element, data server, network resource controller, network apparatus, router, gateway, network node, computer, cloud-based server, web server, application server, proxy server, etc. [00126] FIG. 6 illustrates an example embodiment of an apparatus 9000. The apparatus 9000 may be a device or be included in a device as disclosed herein. The apparatus 9000 may be used for performing one or more or all steps of a positioning method disclosed herein. [00127] As represented schematically by FIG.6, the apparatus 9000 may include at least one processor 9010 and at least one memory 9020. The apparatus 9000 may include one or more communication interfaces 9040 (e.g. network interfaces for access to a wired / wireless network, including Ethernet interface, WIFI interface, etc) connected to the processor and configured to communicate via wired / non wired communication link(s). The apparatus 9000 may include user interfaces 9030 (e.g. keyboard, mouse, display screen, etc) connected with the processor. The apparatus 9000 may further include one or more media drives 9050 for reading a computer-readable storage medium (e.g. digital storage disc 9060 (CD-ROM, DVD, Blue Ray, etc), USB key 9080, etc). The processor 9010 is connected to each of the other components 9020, 9030, 9040, 9050 in order to control operation thereof. [00128] The memory 9020 may include a random access memory (RAM), cache memory, non-volatile memory, backup memory (e.g., programmable or flash memories), read-only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD) or any combination thereof. The ROM of the memory 9020 may be configured to store, amongst other things, an operating system of the apparatus 9000 and / or one or more computer program code of one or more software applications. The RAM of the memory 9020 may be used by the processor 9010 for the temporary storage of data. [00129] The processor 9010 may be configured to store, read, load, execute and/or otherwise process instructions 9070 stored in a computer-readable storage medium 9060, 9080 and / or in the memory 9020 such that, when the instructions are executed by the processor, causes the apparatus 9000 to perform one or more or all steps of a method described herein for the concerned apparatus 9000. [00130] The instructions may correspond to program instructions or computer program code. The instructions may include one or more code segments. A code segment may represent a procedure, function, subprogram, program, routine, subroutine, module, software package, class, or any combination of instructions, data structures or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted via any suitable technique including memory sharing, message passing, token passing, network transmission, etc. [00131] When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. The term “processor” should not be construed to refer exclusively to hardware capable of executing software and may implicitly include one or more processing circuits, whether programmable or not. A processor or likewise a processing circuit may correspond to a digital signal processor (DSP), a network processor, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a System-on-Chips (SoC), a Central Processing Unit (CPU), an arithmetic logic unit (ALU), a programmable logic unit (PLU), a processing core, a programmable logic, a microprocessor, a controller, a microcontroller, a microcomputer, a quantum processor, any device capable of responding to and/or executing instructions in a defined manner and/or according to a defined logic. Other hardware, conventional or custom, may also be included. A processor or processing circuit may be configured to execute instructions adapted for causing the host apparatus or host system to perform one or more functions disclosed herein for the host apparatus or host system. [00132] A computer readable medium or computer readable storage medium may be any tangible storage medium suitable for storing instructions readable by a computer or a processor. A computer readable medium may be more generally any storage medium capable of storing and/or containing and/or carrying instructions and/or data. The computer readable medium may be a non-transitory computer readable medium. The term “non- transitory”, as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). [00133] A computer-readable medium may be a portable or fixed storage medium. A computer readable medium may include one or more storage device like a permanent mass storage device, magnetic storage medium, optical storage medium, digital storage disc (CD- ROM, DVD, Blue Ray, etc), USB key or dongle or peripheral, a memory suitable for storing instructions readable by a computer or a processor. [00134] A memory suitable for storing instructions readable by a computer or a processor may be for example: read only memory (ROM), a permanent mass storage device such as a disk drive, a hard disk drive (HDD), a solid state drive (SSD), a memory card, a core memory, a flash memory, or any combination thereof. [00135] In the present description, the wording "means configured to perform one or more functions" or “means for performing one or more functions” may correspond to one or more functional blocks comprising circuitry that is adapted for performing or configured to perform the concerned function(s). The block may perform itself this function or may cooperate and / or communicate with other one or more blocks to perform this function. The "means" may correspond to or be implemented as "one or more modules", "one or more devices", "one or more units", etc. The means may include at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause an apparatus or system to perform the concerned function(s). [00136] As used in this application, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) combinations of hardware circuits and software, such as (as applicable) : (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions); and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.” [00137] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, an integrated circuit for a network element or network node or any other computing device or network device. [00138] The term circuitry may cover digital signal processor (DSP) hardware, network processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), etc. The circuitry may be or include, for example, hardware, programmable logic, a programmable processor that executes software or firmware, and/or any combination thereof (e.g. a processor, control unit/entity, controller) to execute instructions or software and control transmission and receptions of signals, and a memory to store data and/or instructions. [00139] The circuitry may also make decisions or determinations, generate frames, packets or messages for transmission, decode received frames or messages for further processing, and other tasks or functions described herein. The circuitry may control transmission of signals or messages over a radio network, and may control the reception of signals or messages, etc., via one or more communication networks. [00140] Although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of this disclosure. As used herein, the term "and/or," includes any and all combinations of one or more of the associated listed items. [00141] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the," are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," and/or "including," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. [00142] While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof. [00143] LIST OF MAIN ABBREVIATIONS [00144] AoA Angle of Arrival [00145] AoD Angle of Departure [00146] BS Base Station [00147] CSI-RS Channel State Information Reference Signal [00148] CU Central Unit [00149] DL Downlink [00150] UL Uplink [00151] DoA Direction of Arrival [00152] DU Distributed Unit [00153] LMF Location Management Function [00154] LoS Line of Sight [00155] LPP LTE Positioning Protocol [00156] NLoS Non-Line-of-Sight [00157] NRPPa NR Positioning Protocol A [00158] O-CU Open-Central Unit [00159] O-DU Open-Distributed Unit [00160] ORAN Open Radio Access Network [00161] PRS Positioning Reference Signal [00162] RRC Radio Resource Control [00163] RSRP Reference Signal Received Power [00164] SRS Sounding reference signal [00165] ToA Time of Arrival [00166] UE User Equipment [00167] ULA Uniform Linear Array

Claims

CLAIMS 1. A method comprising: obtaining a mapping function mapping beamforming gain differences and pairs of beam indexes with directions of arrival defined with respect to a first device, wherein a pair of beam indexes consists of indexes identifying two distinct and overlapping beams sent by the first device during beam sweeping procedure; obtaining a first respectively second beam index identifying a first respectively second beam reported by a second device during a beam reporting procedure, where the second beam overlaps the first beam; obtaining a first received signal power difference computed based on a first received signal power measured by the second device for the first beam and a second received signal power measured by the second device for the second beam; determining a direction of arrival of the second device with respect to the first device based on at least a first direction of arrival obtained by applying the mapping function to a beamforming gain difference corresponding to the first received signal power difference and the pair of beam indexes consisting of the first and second beam indexes. 2. The method of claim 1, wherein the first beam is the best beam reported by the second device in a first set of beams and the second beam is the best beam reported by the second device in a second set of beams. 3. The method of claim 1 or 2, wherein a beamforming gain difference and a pair of beam indexes is mapped with at least two directions of arrival. 4. The method of claim 1 o 2, wherein a beamforming gain difference and a pair of beam indexes is mapped with one direction of arrival. 5. The method according to any of the preceding claims, wherein the mapping function is implemented by a look-up table. 6. The method according to any of the preceding claims, wherein the mapping is based on the beamforming patterns used for beams in the first and second sets of beams, where the beamforming patterns defines beamforming gains in a plurality of directions used for beams. 7. The method according to any of the preceding claims, wherein a direction of arrival is mapped with a beamforming gain difference and a given pair of beam indexes when the difference between the beamforming gains used in the direction of arrival for the two beams identified by the concerned pair of beam indexes is equal to the beamforming gain difference. 8. The method according to any of the preceding claims, comprising obtaining a third beam index identifying a third beam reported by a second device; determining a second direction of arrival of the second device with respect to the first device by applying the mapping function to a beamforming gain difference corresponding to the first received signal power difference and the pair of beam indexes consisting of the first and second beam indexes; selecting one of the first and second directions of arrival on the basis of the third beam index, wherein the selected direction of arrival corresponds to a direction that is closer to the boresight direction of the third beam. 9. The method according to claim 8 and 2, wherein the third beam is the second best beam reported by the second device in the first or second set of beams. 10. The method according to claim 8 and 2, comprising obtaining a second received signal power difference computed based on the first received signal power and a third received signal power measured by the second device for the third beam; determining a third direction of arrival of the second device with respect to the first device by applying the mapping function to a beamforming gain difference corresponding to the second received signal power difference and the pair of beam indexes consisting of the first and third beam indexes; selecting as the direction of arrival of the second device with respect to the first device, one of the first and second directions of arrival of the second device that is the closest to the third direction of arrival. 11. The method according to any of the preceding claims, wherein the first device is a base station and the second device is a user equipment or vice versa. 12. The method according to any of the preceding claims, wherein at least one of the first received signal power and the second received signal power is a Reference Signal Received Power, RSRP. 13. The method according to any of the preceding claims, comprising: reporting the direction of arrival of the second device with respect to the first device by a user equipment to a base station or by a base station to a Location Management Function or by a Location Management Function to a base station or by a base station to a user equipment. 14. The method according to any of claims 1 to 13, comprising: receiving at least one of the mapping function, the first and second beam indexes and the first and second received signal power by a Location Management Function from a user equipment or from a base station. 15. The method according to any of claims 1 to 13, comprising: receiving at least one of the mapping function, the first and second beam indexes and the first and second received signal power by a user equipment from a base station. 16. The method according to any of claims 1 to 13, comprising: receiving at least one of the mapping function, the first and second beam indexes and the first and second received signal power by a base station from a user equipment by a Location Management Function or by a base station. 17. An apparatus comprising means for performing a method according to any of the preceding claims. 18. An apparatus according to claim 16, wherein the means comprise - at least one processor; - at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform the method.