Method for computer-aided passive localization of an object using a radio network

Abstract

Method for computer-aided passive localization of an object (O) by means of a radio network, wherein the radio waves of the radio network propagate in a spatial area along a number of propagation paths (PA1, PA2, PA3, PA4, PA1', ..., PAN') between a number of transmitters (TR, TR') and a number of receivers (RE, RE1', ..., REN'), wherein a respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN') represents a previously known transmission path of the radio waves of the radio network between a transmitter (TR, TR') and a receiver (RE, RE1', ..., REN') which are assigned to the respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN'), wherein a) at a particular measuring time from a number of measuring times, signal values ​​(α̂ i (t k)) of the radio network for the number of propagation paths (PA1, PA2, PA3, PA4, PA1', ..., PAN'), wherein the signal value for a respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN') is a signal strength measure of the radio waves received on the respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN') by the receiver (RE, RE1', ..., REN') of the respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN'), and b) from the signal values ​​obtained at the respective measurement time (α̂ i (t k)) the position of the object (O) within the spatial area is estimated at the respective measurement time, characterized in that the number of propagation paths (PA1, PA2, PA3, PA4, PA1', ..., PAN') comprises one or more predetermined propagation paths (PA1', ..., PAN'), wherein a respective predetermined propagation path (PA1', ..., PAN') contains one or more surface elements (4) arranged at previously known positions in the spatial area and each configured as a reconfigurable intelligent surface, for which the radiation characteristic of radio waves is configurable, which are emitted by the reconfigurable intelligent surface in response to incident radio waves, wherein radio waves are incident on a respective surface element (4) along the respective predetermined propagation path (PA1', ..., PAN'), which radio waves consist of radio waves from the transmitter (TR') of the respective predetermined propagation path (PA1', ..., PAN'), and the respective surface element (4) converts the radio waves falling thereon into radio waves which are emitted by the respective surface element (4) with a previously configured radiation characteristic, wherein at least a portion of the emitted radio waves reaches the receiver (RE1', ..., REN') of the respective predetermined propagation path (PA1', ..., PAN') along the respective predetermined propagation path.

Description

[0001] The invention relates to a method and a device for computer-aided passive localization of an object by means of a radio network.

[0002] It is known from the state of the art to use radio waves from a radio network, which are transmitted between corresponding transmitters and receivers, to spatially locate objects. Signal attenuation of the radio signals along their propagation paths between the respective transmitters and receivers is recorded and evaluated. This signal attenuation provides information about the position of the object to be located, because the physical size of the object reduces the signal strength along the propagation path the object is currently crossing.

[0003] The publication [1] describes a method for computer-aided localization of an object via radio waves, which analyses the signal strengths of the radio network on direct propagation paths, i.e. in line of sight between respective transmitters and receivers, in order to determine the position of the object.

[0004] The publication [2] describes a method for locating an object using a radio network, in which, in addition to signal strengths of the radio network on direct propagation paths between respective transmitters and receivers, signal strengths on so-called multi-path propagation paths are also taken into account, on which radio waves are transmitted with the interposition of reflections and scatterings.

[0005] To locate objects using the methods mentioned above, knowledge of the corresponding propagation paths is required. This knowledge can be obtained, for example, from the geometric dimensions of the spatial area in which the localization takes place, as well as the spatial positions of the radio network's transmitters and receivers.

[0006] Conventional localization methods have the disadvantage that the propagation paths of the radio waves for which signal attenuations are detected are fixed and cannot be adjusted.

[0007] The documents [5] and [6] each disclose methods for the active localization of an object by means of a radio network, wherein the object is a wireless communication device which receives radio signals of the radio network and evaluates them for localization.

[0008] The object of the invention is to provide a method for computer-aided passive localization of an object using a radio network in which the propagation paths used for localization can be adapted.

[0009] This object is achieved by the method according to claim 1. Further developments of the invention are defined in the dependent claims.

[0010] The inventive method for computer-aided passive localization of an object utilizes a radio network whose radio waves propagate in a spatial area along a number (preferably a plurality) of propagation paths between a number (preferably a plurality) of transmitters and a number (preferably a plurality) of receivers. Each propagation path represents a known transmission path of the radio waves of the radio network between a transmitter and a receiver, which are assigned to the respective propagation path.

[0011] In a step a) of the method according to the invention, signal values ​​of the radio network for the number of propagation paths are obtained at a respective measuring time from a number (preferably a plurality) of measuring times, wherein the signal value for a respective propagation path is a signal strength measure of the radio waves received on the respective propagation path by the receiver of the respective propagation path (i.e. by the receiver assigned to the respective propagation path). In particular, these signal values ​​are determined from the radio signal detected at the receiver by means of a method for channel estimation known per se, such as the algorithm from document [4]. In this case, the signal values ​​represent the change in signal strength or the signal strength relative to a time-averaged signal strength. The decrease in this signal strength can be used to detect signal attenuation caused by an object on or near the network.caused near a corresponding propagation path.

[0012] In a step b) of the method according to the invention, the position of the object within the spatial region at the respective measurement time is estimated from the signal values ​​obtained at the respective measurement time, for which purpose the method described in document [2] can be used, for example. The term “estimation of the position” is to be understood broadly. In particular, it is not necessarily necessary to specify a value for the position, but the estimated position can also be specified merely by a spatial section of the spatial region in which the object is located. In a simple variant, the position estimation can, for example, provide the result that the object is located on a certain propagation path or a certain section of a corresponding propagation path.

[0013] The method according to the invention is characterized in that the number of propagation paths comprises one or more specific propagation paths, which are referred to below as predefined propagation paths. Each predefined propagation path contains one or more surface elements arranged at known positions in the spatial domain and each configured as a reconfigurable intelligent surface. Reconfigurable intelligent surfaces, also referred to as RIS surfaces, are well known in the art and are described, for example, in publication [3].Reconfigurable intelligent surfaces generally refer to surfaces for which the radiation characteristics of radio waves emitted by the reconfigurable intelligent surface in response to incident radio waves are configurable. Thus, regardless of the angle of incidence at which radio waves strike the reconfigurable intelligent surface, re-radiation of radio waves with any radiation characteristics can be achieved.

[0014] In the method according to the invention, radio waves originating from radio waves of the transmitter of the respective predefined propagation path (i.e., the transmitter associated with the respective predefined propagation path) impinge on a respective surface element configured as a reconfigurable intelligent surface along the respective predefined propagation path. The radio waves impinging on the surface element can be radio waves emitted directly from the transmitter in line of sight to the surface element, or possibly also radio waves that have previously passed through scattering or reflecting objects or one or more other reconfigurable intelligent surfaces.

[0015] The respective surface element on the respective predetermined propagation path converts the radio waves falling thereon into radio waves which are emitted by the respective surface element with a previously configured radiation characteristic, wherein at least a portion of the emitted radio waves reaches the receiver of the respective predetermined propagation path (i.e., the receiver associated with the respective predetermined propagation path) along the respective predetermined propagation path.

[0016] The method according to the invention has the advantage that, through the use of reconfigurable intelligent surfaces, corresponding propagation paths can be appropriately adapted, or new propagation paths can be added or removed if necessary. This allows, for example, the accuracy of localization in certain subsections of the spatial area to be changed.

[0017] In a preferred embodiment of the invention, at least one of the predetermined propagation paths is a specific propagation path containing a single surface element (i.e., only one surface element) onto which radio waves fall along the specific propagation path in line of sight to the transmitter of the specific propagation path (i.e., the transmitter associated with the specific propagation path). At least a portion of the radio waves converted by the single surface element along the specific propagation path is received at the receiver of the specific propagation path (i.e., at the receiver associated with the specific propagation path) in line of sight to the single surface element. A specific propagation path is thus characterized in that radio waves are transmitted in a straight line both from the transmitter to the surface element and from the surface element to the receiver.This means that no additional reflections or scattering occur along the propagation path. This ensures a high signal strength of the radio waves along the propagation path.

[0018] In a preferred variant of the embodiment just described, the transmitter of the specific propagation path directs the radio waves as a radiation lobe toward the individual surface element. Alternatively, however, it is also possible for the transmitter to transmit radio waves homogeneously into a predetermined spatial segment and, if necessary, omnidirectionally, provided that a portion of the radio waves reaches the individual surface element. However, by transmitting the radio waves as a radiation lobe, higher signal strengths are achieved for the radio signals on the corresponding propagation path.

[0019] In a further variant of the method according to the invention, at least one predetermined propagation path contains a plurality of surface elements. It is also possible for at least one predetermined propagation path to contain, in addition to the surface element(s), one or more scattering objects at which radio waves are scattered (i.e., diffusely deflected) along the predetermined propagation path. Alternatively or in addition to scattering objects, the predetermined propagation path can also contain one or more reflection objects at which radio waves are reflected (i.e., directionally deflected) along the predetermined propagation path.

[0020] In a further preferred embodiment of the invention, the number of predetermined propagation paths contains a group of predetermined propagation paths, wherein the same transmitter but different receivers are assigned to the predetermined propagation paths of the group, and wherein the predetermined propagation paths of the group contain the same surface element(s). Preferably, the predetermined propagation paths of the group are the specific propagation paths described above, in which radio waves are transmitted in line of sight between the transmitter and the surface element and between the surface element and the receiver.

[0021] With the variant of the invention just described, information about the estimated position of the object can be easily derived. If the signal values ​​on all specific propagation paths in a group indicate attenuation, it can be concluded that the object is located on or near the line of sight between the transmitter and the surface element. If, however, only the signal value from a specific propagation path in the group indicates signal attenuation, it can be concluded that the object is located on or near the line of sight between the surface element and the receiver of the specific propagation path.

[0022] In one variant of the method according to the invention, at least one surface element containing at least one predefined propagation path radiates radio waves homogeneously in a predefined solid angle and, if necessary, omnidirectionally. Nevertheless, it is also possible for at least one surface element containing at least one predefined propagation path to emit the radio waves as one or more radiation lobes, with each radiation lobe extending in the direction of a predefined propagation path. This allows higher signal strengths of the radio waves to be achieved on the corresponding propagation paths.

[0023] The method according to the invention can be used in any wireless network. For example, a WLAN network from the IEEE 802.11 standard family, e.g., WiFi 6 (IEEE 802.11ax standard), can be used as the wireless network. It is also possible for the wireless network to be a UWB network (UWB = Ultra Wide Band) according to the IEEE 802.15-4 standard family. Furthermore, the wireless network can be a mobile network (e.g., 5G or 6G).

[0024] In addition to the method described above, the invention relates to a device for computer-assisted passive localization of an object using a radio network, wherein the device is configured to carry out the method according to the invention or one or more preferred variants of the method according to the invention. The device thus contains the transmitter(s), the receiver(s), and the surface element(s) used in the method according to the invention to generate a corresponding radio network with the predetermined propagation path(s) of the radio waves. Furthermore, the device contains corresponding means for obtaining signal values ​​on the propagation paths and estimating the position of the object therefrom.

[0025] Embodiments of the invention are described in detail below with reference to the attached figures.

[0026] They show: Fig. 1 a schematic plan view of a spatial area with a radio network extending therein, which generally explains the principle of passive localisation of an object by means of radio waves; Fig. 2 a diagram showing a measured channel impulse response for a radio signal of the radio network from Fig. 1 illustrates; Fig. 3 a diagram showing the signal strength change for a propagation path from Fig. 1 taking into account the movement of the Fig. 1 represents the user represented; Fig. 4 a schematic representation of propagation paths running over a RIS surface, which are used in one embodiment of the invention for the passive localization of an object.

[0027] The following will be based on Fig. 1 to Fig. 3, the principle of passive localization of an object is explained in general terms. This principle is also used by the invention, with an embodiment of the invention being shown with reference to Fig. 4 is described.

[0028] In the example of Fig. 1, a passive localization of an object O is performed in a spatial area in which a radio network is installed. The object O is a human user moving along a trajectory L. The radio network comprises a plurality of network nodes or access points, each of which can transmit and receive corresponding radio signals. In Fig. 1 shows two of these network nodes represented by black dots as examples. During passive localization, the radio signal from network node TR, which acts as a transmitter, is evaluated. This radio signal is received by network node RE, which acts as a receiver. Independently of this, network node TR can also receive radio signals, and network node RE can also transmit radio signals. In the embodiment described here, the radio network is based on the UWB standard (IEEE 802.15-4 family). Nevertheless, the radio network can also be based on a different standard, such as WLAN (IEEE 802.11 family). Likewise, the radio network can be a cellular network.

[0029] The Fig. The spatial area shown in Figure 1 is delimited by two walls 1 and 2 and contains the network nodes TR and RE as well as a scattering object 3. The dominant signal propagation paths between the transmitter TR and the receiver RE are indicated by lines with corresponding reference symbols PA1, PA2, PA3 and PA4. The propagation path PA1 is the so-called LoS path (LoS = Line of Sight), which corresponds to the line of sight between the transmitter TR and the receiver RE. The line of sight represents the direct propagation of the radio waves (i.e. without reflections) between the transmitter TR and the receiver RE. The propagation path PA2 represents a path with a reflection of the radio waves on the wall 1 and the propagation path PA3 represents a path with a reflection of the radio waves on the wall 2. In contrast, the propagation path PA4 is a path in which the radio waves are scattered by the scattering object 3.

[0030] In the scenario of Fig. 1, the positions PO0, PO1, PO2, and PO3 of object O at the respective times t0, t1, t2, and t3 are to be estimated using passive localization. For this purpose, the course of the propagation paths PA1 to PA4 is required. This has been appropriately determined in advance. For example, this course can be derived from knowledge of the dimensions of the spatial area and the positions of the objects contained therein (i.e., walls 1, 2, the transmitter TR, the receiver RE, and the scattering object 3).

[0031] The following section first explains the form of the radio signals received at the receiver RE, before discussing passive localization in more detail. The individual signal components received via the various propagation paths are received with different propagation delays due to the different lengths of the propagation paths. This results in a channel impulse response (CIR) for a received radio signal, which is a superposition of the signal components of the various propagation paths between the transmitter TR and the receiver RE that are attenuated along the signal transmission. In general, the channel impulse response (CIR) is the sum of an infinite number of propagation paths. However, the receiver RE can only detect signals whose power lies above a certain sensitivity threshold.

[0032] Fig. Figure 2 shows, as an example, the channel impulse response measured by the receiver RE for a radio signal pulse transmitted by the transmitter TR in accordance with the UWB standard IEEE 802.15-4a. The propagation distance τ c (delay time multiplied by the speed of light) in meters is plotted along the abscissa, and the magnitude A of the signal amplitude (i.e., the signal strength in the form of the received signal power) is plotted along the ordinate. The corresponding signal propagation paths result as peaks in the channel impulse response, with the propagation paths associated with the peaks referenced by the reference symbols PA1 to PA4 of these paths. As expected, the direct LoS propagation path between the transmitter TR and the receiver RE has the signal with the highest signal strength, whereas the other propagation paths exhibit significantly lower signal strengths.

[0033] The channel impulse response h(t k , τ) can be determined at discrete times t kthe signal detection by a finite number of N signal components corresponding to the different propagation paths can be described as follows: h(tk,τ)=Σi=1N αi⋅δ(τ−τi(tk))

[0034] Here, δ(·) denotes the Dirac distribution. Each signal component corresponds to a propagation path and is determined by the time-varying propagation delay τ i (t k ) and the time-varying complex amplitude α i (t k ). Here, i = 1 corresponds to the LoS propagation path, which according to Fig. 1 is the propagation path PA1. In the embodiment described here, stationary network nodes (ie a stationary transmitter TR and a stationary receiver RE) are considered, so that the respective propagation delays are fixed in time, ie τ i (t k ) = τ i .

[0035] The received radio signal is bandwidth-limited, ie it is sampled in the time domain with a resolution of 1 / B, where B is the bandwidth. Consequently, the signal amplitude of a single sample is a sum of different contributions. Furthermore, the received radio signal is influenced by noise. In the variant of the inventive method described here, the channel impulse response CIR is measured, and from this, the amplitude α is determined using a known channel estimation. i (t k ) and propagation delay τ i for the corresponding signal component (ie the corresponding propagation path). The propagation delay only needs to be calculated for a time t k be determined since the network nodes are stationary. Alternatively, the propagation delay can be a time delay calculated over the times t k averaged value. From the amplitude α i (t k) the change α̂ i (t k ) of the signal strength or signal power |α i (t k )| relative to the signal strength |α mean | determines the average signal strength across all measurements processed for the corresponding propagation path. The signal strength change, or the signal strength relative to the average signal strength, is thus given as follows: α^i(tk)=|αi(tk) / αmean|

[0036] In a preferred variant, the channel estimation is carried out to determine the amplitude α i (t k ) and the propagation delay τ i based on the algorithm from [4]. However, other known algorithms for channel estimation can also be used. From the determined propagation delay τ i the corresponding propagation path results, to which in turn the corresponding signal change α̂ i (t k ) heard.

[0037] The aim of passive localization is now to determine the effects of the object O on the above signal strength values ​​α̂ i (t k ) during the movement of the object along the trajectory L. This makes use of the knowledge that due to the physical size of the object O, its presence on or near a propagation path leads to a signal attenuation, ie the signal strength value α̂ i (t k ) on the corresponding propagation path decreases. This effect is exemplified in Fig. 3. This figure shows the scenario of Fig. 1 determined signal strength change α̂ i (t k ) in dB for the propagation path PA2 (ie i=2) as a function of time t. Fig. 3 the recording times t0 to t3 according to the Fig. 1 highlighted by dashed vertical lines.

[0038] How to Fig. 3, no significant change in signal strength occurs at times t0 and t1, i.e., when the user is far away from propagation path PA2. Rather, the signal fluctuations are due to noise. At time t2, i.e., when the user is located on propagation path PA2, the signal is strongly attenuated due to the user's physical size, which results in a decrease in the signal strength value α̂. i (t k ) at time t2. After the user has crossed the propagation path PA2 and moved away from it, at the corresponding time t3 there is no longer any signal attenuation, so that the strength of the signal of the Fig. 3 at time t3 is essentially at the same level as at times t0 and t1.

[0039] From the above information on the signal strength change on the respective propagation paths, the position of the object O can be estimated using known methods. For example, for the scenario of Fig. 1 the method described in the above-mentioned publication [2] can be used, which also takes into account multipath propagation paths with reflections or scattering of the radio waves, as is also the case in the scenario of Fig. 1 is the case.

[0040] In conventional methods for passive localization, only propagation paths are considered in which radio waves are transmitted in line of sight between transmitter and receiver or with the interposition of scattering and / or reflecting objects between transmitter and receiver. The properties of the scattering or reflecting objects cannot be influenced, so that the propagation paths cannot be influenced during localization. In contrast, in the embodiment of the invention described below, at least some propagation paths are used that can be suitably adjusted or changed. This allows the localization to be flexibly adapted, for example by increasingly placing propagation paths in an area in which the presence of the corresponding object to be localized is suspected.

[0041] The variable propagation paths used in the invention are implemented using surface elements in the form of known reconfigurable intelligent surfaces, which are also referred to below as RIS surfaces. Depending on the configuration, only propagation paths via RIS surfaces can be used in the method according to the invention. Nevertheless, already known propagation paths, such as LoS paths or multipath propagation paths, can also be used for localization, as described, for example, in Fig. 1 are shown.

[0042] Fig. Figure 4 shows an example of a variant of the method according to the invention, which uses propagation paths over a single surface element 4 in the form of a RIS surface for localization. In Fig. 4 is a plan view of a room area analogous to Fig. 1, in which an object O in the form of a human user is to be localized during its movement along the trajectory L. Examples are Fig. 4 three measurement times t0, t1 and t N specified at which the user's position is to be estimated using the signal strength changes on corresponding propagation paths.

[0043] The Fig. The RIS interface shown in Figure 4 can control or modify the radiation characteristics of radio waves emitted in response to incoming radio waves. Typically, the RIS interface uses a variety of discrete elements with controllable radiation characteristics. These elements include, for example, passive circuits that re-emit incoming radio signals after filtering them without increasing the power of the radio signal.

[0044] Fig. Figure 4 shows a scenario in which a transmitter TR' with a known position directs radio waves toward the surface element 4. In other words, the radio waves from the transmitter TR' are directed as a radiation lobe SK toward the surface element 4. Alternatively, it is also possible for the transmitter TR' to emit radio waves homogeneously into a predetermined spatial segment and, if necessary, omnidirectionally, provided the radio waves reach the surface element 4. The use of a directed radiation lobe SK toward the surface element 4 has the advantage that higher signal strengths can be achieved.

[0045] In addition to the transmitter TR', the radio network of the Fig. 4 also a plurality of receivers REi' (i=1, 2, ...N). For the surface element 4, a radiation characteristic was set or configured in which radio waves are emitted in a directed manner via a total of N radiation lobes SK1 to SKN, with each radiation lobe SKi (i=1, 2, ...N) directed at an associated receiver REi' (i=1, ..., N). The surface element 4 activates the individual radiation lobes sequentially at a very high frequency. The time span for switching between the radiation lobes is negligible compared to the speed at which the object O is moving. In other words, the radiation lobes Ski are received essentially simultaneously by the respective receivers REi'.

[0046] As part of the localization, the signal strengths are recorded at the respective receivers RE1' to REN' at the corresponding measuring times according to the above equation (2). These signal strengths are processed in a common computer device 5, which is exemplary in Fig. 4 is represented as a computer cloud. In the scenario of Fig. 4 results in a total of N novel propagation paths PA1' to PAN', which are not used in conventional methods and run over the surface element 4. These propagation paths are shown in Fig. 4 is indicated by dashed lines. All propagation paths have the same section between receiver TR' and surface element 4. However, the section of the propagation paths between surface element 4 and the respective receivers RE1' to REN' is different.

[0047] The propagation paths PA1' to PAN' can be treated as multipath propagation paths within the framework of passive localization. In particular, the following propagation delay results for a respective propagation path PAi' (i=1, ..., N): τiRIS=(‖rRIS−rTR'‖+‖rRIS−rREi'‖) / c

[0048] Here r denotes TR' the previously known position of the transmitter TR', r REi' the previously known position of the respective receiver REi' (i = 1, ..., N) and r RIS the previously known position of the surface element 4. Furthermore, c corresponds to the speed of light.

[0049] For the above propagation paths PA1' to PAN', the propagation delay and the signal strength change for the corresponding propagation path are again determined using a known channel estimation. Using the above equation (3), a measured propagation delay can be assigned to a propagation path with the corresponding signal strength change. Using the method from document [2], the position of object O can then be estimated from the signal strength changes on the propagation paths PA1' to PAN' running across surface element 4.

[0050] In a very simple implementation of the method according to the invention, the position of the object O is estimated very roughly, with the position estimation merely indicating whether the object is located on the path segment of the propagation paths between the transmitter TR' and the surface element 4 or on one of the path segments between the surface element 4 and a corresponding receiver REi'. In other words, the following conclusions are drawn from the signal strength changes on the propagation paths recorded at a respective measurement time: i) For a measurement time, attenuations in the signal strength occur on all propagation paths PA1' to PAN' (corresponds to the time t0 in Fig. 4): This leads to the conclusion that the object O is located on or near the path section between transmitter TR' and surface element 4. ii) Only for one path PAi' (i = 1, ... N) an attenuation in the signal strength is detected (corresponds to time t1 for i = 1 and to time t for i = N N in Fig. 4): This leads to the conclusion that the object O is located on or near the path section of the propagation path PAi' between surface element 4 and receiver REi'. iii) There is no attenuation in the signal strength on any of the propagation paths PA1' to PAN': This leads to the conclusion that the object O is not located near any of the propagation paths PA1' to PAN'.

[0051] In the foregoing, an embodiment of the invention was described in which the propagation paths PA1' to PAN' extend over a single surface element 4, and the sections of the propagation paths lie on the line of sight between the transmitter and surface element or between the surface element and receiver. However, in a modified embodiment, it is also possible to consider propagation paths that transmit the radio waves over several intermediate surface elements or that also include other objects at which radio waves are reflected or scattered.

[0052] Furthermore, it is not absolutely necessary for the corresponding surface element 4 to transmit radio waves to corresponding receivers via radiation lobes. Rather, it is also possible for the surface element to transmit radio waves homogeneously into a predetermined spatial segment and, if necessary, omnidirectionally, provided that they can be received by all receivers along the corresponding propagation paths.

[0053] The embodiments of the invention described above offer a number of advantages. In particular, novel propagation paths across RIS surfaces are considered for object localization. This makes it possible to flexibly adapt the propagation paths by appropriately modifying the radiation characteristics of the corresponding surface elements. For example, propagation paths can be activated in specific spatial areas if high localization accuracy is required there or if the object to be located is suspected to be located there. Bibliography: [1] J. Wilson, N. Patwari, “Radio tomographic imaging with wireless networks,” IEEE Transactions on Mobile Computing, Vol. 9, No. 5, pages 621-632, May 2010 [2] M. Schmidhammer, C. Gentner, S. Sand, U.-C. Fiebig, “Multipath-enhanced device-free localization in wideband wireless networks,” IEEE Antennas and Wireless Propagation Letters, Vol. 20, No. 4, pages 453-457, 2021 [3] E. Bjoernson, H. Wymeersch, B. Matthiesen, P. Popovski, L. Sanguinetti, E. de Carvalho, “Reconfigurable intelligent surfaces: A signal processing perspective with wireless applications,” IEEE Signal Processing Magazine, Vol. 39, No. 2, pages 135-158, 2022 [4] BH Fleury, M. Tschudin, R. Heddergott, D. Dahlhaus, KI Pedersen, “Channel Parameter Estimation in Mobile Radio Environments using SAGE algorithm”, IEEE J. Sel. Areas Commun., Vol. 17, No. 3, pages 434-450, March 1999 [5] WO 2023 / 049553 A1 [6] WO 2022 / 216351 A1

Claims

[1] Method for the computer-aided passive localization of an object (O) by means of a radio network, wherein the radio waves of the radio network propagate in a spatial area along a number of propagation paths (PA1, PA2, PA3, PA4, PA1', ..., PAN') between a number of transmitters (TR, TR') and a number of receivers (RE, RE1', ..., REN'), wherein a respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN') represents a previously known transmission path of the radio waves of the radio network between a transmitter (TR, TR') and a receiver (RE, RE1', ..., REN') which are assigned to the respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN'), wherein a) at a particular measuring time from a number of measuring times, signal values ​​(α̂ i (t k)) of the radio network for the number of propagation paths (PA1, PA2, PA3, PA4, PA1', ..., PAN'), wherein the signal value for a respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN') is a signal strength measure of the radio waves received on the respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN') by the receiver (RE, RE1', ..., REN') of the respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN'), and b) from the signal values ​​obtained at the respective measurement time (α̂ i (t k )) the position of the object (O) within the spatial area is estimated at the respective measurement time, characterized bythat the number of propagation paths (PA1, PA2, PA3, PA4, PA1', ..., PAN') comprises one or more predetermined propagation paths (PA1', ..., PAN'), wherein a respective predetermined propagation path (PA1', ..., PAN') contains one or more surface elements (4) arranged at known positions in the spatial domain and each configured as a reconfigurable intelligent surface, for which the radiation characteristic of radio waves is configurable, which are emitted by the reconfigurable intelligent surface in response to incident radio waves, wherein radio waves are incident on a respective surface element (4) along the respective predetermined propagation path (PA1', ..., PAN'), which radio waves consist of radio waves of the transmitter (TR') of the respective predetermined propagation path (PA1', ..., PAN'), and the respective surface element (4) converts the radio waves falling thereon into radio waves which are emitted by the respective surface element (4) with a previously configured radiation characteristic, wherein at least a portion of the emitted radio waves reaches the receiver (RE1', ..., REN') of the respective predetermined propagation path (PA1', ..., PAN') along the respective predetermined propagation path. [2] Method according to claim 1, characterized byin that at least one of the predetermined propagation paths (PA1', ..., PAN') is a specific propagation path which contains an individual surface element (4) onto which radio waves fall along the specific propagation path in line of sight to the transmitter (TR') of the specific propagation path (PA1', ..., PAN'), wherein at least a portion of the radio waves converted by the individual surface element (4) along the specific propagation path is received at the receiver (RE1', ..., REN') of the specific propagation path in line of sight to the individual surface element (4). [3] Method according to claim 2, characterized by that the transmitter (TR') of the specific propagation path (PA1', ..., PAN') directs the radio waves as a radiation lobe (SK) onto the individual surface element (4). [4] Method according to one of the preceding claims, characterized bythat at least one predetermined propagation path (PA1', ..., PAN') contains several surface elements (4). [5] Method according to one of the preceding claims, characterized by that at least one predetermined propagation path (PA1', ..., PAN') contains, in addition to the surface element(s) (4), one or more scattering objects (3) at which radio waves are scattered along the predetermined propagation path (PA1', ..., PAN'), and / or one or more reflection objects (1, 2) at which radio waves are reflected along the predetermined propagation path (PA1', ..., PAN'). [6] Method according to one of the preceding claims, characterized bythat the number of predetermined propagation paths (PA1', ..., PAN') contains a group of predetermined propagation paths (PA1', ..., PAN'), wherein the same transmitter (TR') but different receivers (RE1', ..., REN') are assigned to the predetermined propagation paths (PA1', ..., PAN') of the group and wherein the predetermined propagation paths (PA1', ..., PAN') of the group contain the same surface element(s) (4). [7] Method according to claim 6 in combination with claim 2 or 3, characterized by that the given propagation paths (PA1', ..., PAN') of the group are specific propagation paths. [8] Method according to one of the preceding claims, characterized by that at least one surface element (4), which contains at least one predetermined propagation path (PA1', ..., PAN'), radiates radio waves homogeneously into a predetermined solid angle. [9] Method according to one of the preceding claims, characterized bythat at least one surface element (4), which contains at least one predetermined propagation path (PA1', ..., PAN'), emits the radio waves as one or more radiation lobes, wherein a respective radiation lobe (SK1, ..., SKN) runs in the direction of a predetermined propagation path (PA1', ..., PAN'). [10] Method according to one of the preceding claims, characterized by that the radio network is a WLAN network or a UWB network or a cellular network. [11] Device for the computer-aided passive localization of an object (O) by means of a radio network, wherein the radio waves of the radio network propagate in a spatial area along a number of propagation paths (PA1, PA2, PA3, PA4, PA1', ..., PAN') between a number of transmitters (TR, TR') and a number of receivers (RE, RE1', ..., REN'), wherein a respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN') represents a previously known transmission path of the radio waves of the radio network between a transmitter (TR, TR') and a receiver (RE, RE1', ..., REN') which are assigned to the respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN'), wherein the device is designed to carry out a method in which: a) at a particular measuring time from a number of measuring times, signal values ​​(α̂ i (t k)) of the radio network for the number of propagation paths (PA1, PA2, PA3, PA4, PA1', ..., PAN'), wherein the signal value for a respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN') is a signal strength measure of the radio waves received on the respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN') by the receiver (RE, RE1', ..., REN') of the respective propagation path (PA1, PA2, PA3, PA4, PA1', ..., PAN'), and b) from the signal values ​​obtained at the respective measurement time (α̂ i (t k )) the position of the object (O) within the spatial area is estimated at the respective measurement time, characterized bythat the number of propagation paths (PA1, PA2, PA3, PA4, PA1', ..., PAN') comprises one or more predetermined propagation paths (PA1', ..., PAN'), wherein a respective predetermined propagation path (PA1', ..., PAN') contains one or more surface elements (4) arranged at known positions in the spatial domain and each configured as a reconfigurable intelligent surface, for which the radiation characteristic of radio waves is configurable, which are emitted by the reconfigurable intelligent surface in response to incident radio waves, wherein radio waves are incident on a respective surface element (4) along the respective predetermined propagation path (PA1', ..., PAN'), which radio waves consist of radio waves of the transmitter (TR') of the respective predetermined propagation path (PA1', ..., PAN'), and the respective surface element (4) converts the radio waves falling thereon into radio waves which are emitted by the respective surface element (4) with a previously configured radiation characteristic, wherein at least a portion of the emitted radio waves reaches the receiver (RE1', ..., REN') of the respective predetermined propagation path (PA1', ..., PAN') along the respective predetermined propagation path. [12] Device according to claim 11, characterized by that the device is designed to carry out a method according to one of claims 2 to 10.

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