Method for the computer-aided determination of the course of a number of propagation paths of radio waves between a transmitter and a receiver of a radio network, associated device, computer programme product, and computer programme

Abstract

The invention relates to a method for the computer-aided determination of the course of a number of propagation paths (PA1, PA2, PA3, PA4) of radio waves between a transmitter (TR) and a receiver (RE) of a radio network, wherein: a) signal values (I) are determined by accessing a measurement in which a plurality of object positions (PO0, PO1, PO2, PO3), in combination with radio signals of the radio network, are detected for one or more objects (O, O') which are moving within the spatial area (R), wherein the signal values (I) contain a number of signal values (I) for each object position (PO0, PO1, PO2, PO3), wherein each signal value ((I) of the number of signal values (I) belongs to a propagation path (PA1, PA2, PA3, PA4) and is a signal strength measure of the radio waves which are received at the receiver (RE) on said propagation path at the time of detecting the object position; b) a map (MA) of the spatial area (R) is determined for each propagation path (PA1, PA2, PA3, PA4), in which map object positions (PO0, PO1, PO2, PO3) are marked, wherein, for each marked object position, the signal value (I) belonging to the relevant propagation path (PA1, PA2, PA3, PA4) is attenuated; c) a number of lines (gi), along which the marked object positions (PO0, PO1, PO2, PO3) extend in the spatial area (R), are extracted from the map (MA); d) the course of each propagation path (PA1, PA2, PA3, PA4) is determined based on the number of lines (gi).

Description

[0001] P2930PC00 German Aerospace Center eV Königswinterer Str.522-524 53227 Bonn ____________________________________________________________________ Method for the computer-aided determination of the course of a number of propagation paths of radio waves between a transmitter and a receiver of a radio network ____________________________________________________________________ Description The invention relates to a method for the computer-aided determination of the course of a number of propagation paths of radio waves between a transmitter and a receiver of a radio network. In a radio network, radio waves are generally transmitted between a transmitter and a receiver not only on a direct connection path between the transmitter and receiver, but also via so-called multipath propagation paths with the interposition of reflections and scattering.The information about the course of the existing propagation paths of radio waves between transmitter and receiver can be used, for example, in the context of passive localization in order to determine the position of the object to be located via the attenuation of the radio waves caused by the propagation paths. Such passive localization is described, for example, in document [1]. Furthermore, conclusions about the geometry of the spatial area in which the radio network is installed can be drawn from the course of propagation paths. To determine the course of propagation paths, there are state-of-the-art so-called ray tracing methods that use models of the environment to determine the transmission paths of radio waves. Ray tracing methods do not include any verification as to whether the propagation paths determined in this way actually occur in the corresponding spatial environment.The object of the invention is to obtain the course of one or more propagation paths of radio waves in a radio network from radio signal measurements. This object is achieved by the method according to patent claim 1. Further developments of the invention are defined in the dependent claims. The method according to the invention provides a computer-aided or computer-implemented method for determining the course of a number of propagation paths (ie at least one propagation path) of radio waves between a transmitter and a receiver of a radio network. The positions of the transmitter and receiver are known in advance and are fixed during implementation of the method. The radio network covers a spatial area, and a respective propagation path represents a transmission path of the radio waves of the radio network in the spatial area between the transmitter and the receiver.The method preferably serves to determine the course of multipath propagation paths along which reflections have occurred in the spatial area. In addition, the course of the propagation paths is preferably determined in a two-dimensional representation of the spatial area, in particular with reference to a plan view of the spatial area (ie in a horizontal sectional plane of the spatial area). In a step a) of the method according to the invention, a measurement is accessed that is currently being carried out or has already been completed. This enables P2930PC00 to access corresponding measurement data of the currently carried out or already completed measurement. During the measurement, a plurality of object positions are or were recorded for one or more objects that move in the spatial area in combination with respective radio signals of the radio network. In other words, at the time of recording an object position, ieThe position of the object, or of one of the objects in the case of multiple objects, is detected by a radio signal measurement in the radio network. The term "radio signals" refers to those measurable signals of the radio network from which the number of signal values ​​described below can be obtained. The above term "moving object" is to be understood broadly. In particular, an object does not necessarily have to be a moving object; it can also be a human user moving within the spatial area. Likewise, the object can possibly be an animal.Within the scope of step a) of the method according to the invention, a number of signal values ​​for a respective object position are determined, wherein a respective signal value of the number of signal values ​​belongs to a propagation path and is a signal strength measure of the radio waves received at the receiver on this propagation path at the time the respective object position is detected. The term signal strength measure is to be understood broadly and can include any value that represents the strength of the incoming radio waves. In particular, the signal strength measure can be represented by the received power on the corresponding propagation path or depend on this power. The determination of corresponding signal values ​​or signal strength measures that belong to a propagation path is known per se from the prior art.In particular, this information can be determined using known channel estimation methods from a channel impulse response at the receiver in response to a radio signal pulse at the transmitter. For example, the method described in document [2] can be used as channel estimation. P2930PC00 In a step b) of the method according to the invention, a map of the spatial region is determined for a respective propagation path, in which map object positions from at least some of the plurality of object positions are marked. For a marked object position, the signal value belonging to the respective propagation path is attenuated according to a predetermined criterion compared to an average value of the signal values ​​belonging to the respective propagation path across all object positions of at least some of the plurality of object positions. Step b) thus highlights those object positions at which the object is currently on oris located near the propagation path under consideration. The term map represents a digital representation of an image of the spatial region in which object positions are marked. The map itself does not have to be visualized. In a step c) of the method according to the invention, a number and in particular a plurality of lines along which the marked positions extend in the spatial region are extracted from the map determined for the respective propagation path. The extraction of the number of lines can be carried out using a method known per se. In a preferred embodiment, the number of lines is extracted using a Hough transformation.Finally, in a step d) of the method according to the invention, the course of the respective propagation path is determined from the number of lines, wherein the course is composed of one or more connected sections of at least some of the number of lines. The method according to the invention is based on the finding that by determining object positions for which signal attenuation of radio waves occurs, the course of the propagation path attenuated by the object can be easily determined by line extraction. The course of the respective propagation paths is thus not obtained purely by modeling, but is determined from measured radio signals. The course of the propagation paths can be used, for example, to verify the results of ray tracing methods.Likewise, the course of the propagation paths can be processed in a method for passive localization, such as the method described in document [1]. Furthermore, information about the geometry of the spatial area in which the radio network is installed can be obtained from the measured courses of the propagation paths. In a preferred variant of the method according to the invention, in step a) for a respective object position, in addition to the number of signal values, a number of delay values ​​are determined, wherein each delay value belongs to a propagation path and is a measure of the transmission time of the radio waves on this propagation path from the transmitter to the receiver. Analogous to the signal values, these delay values ​​can be obtained using known channel estimation methods, such as the method described in document [2].The delay value can represent any value that represents the transmission time of the radio waves between transmitter and receiver. For example, the delay value can directly represent the transmission time or the length of the propagation path along which the radio waves propagate. In one variant of the method according to the invention, a plurality of object positions of a single object moving in the spatial area are or were recorded during the measurement accessed in step a).Alternatively, it is also possible for a plurality of object positions of several objects moving in the spatial area to be recorded during the measurement, wherein at least some of the plurality of object positions taken into account in step b) of the method according to the invention only contains those object positions which each belong to an object which was the only object in the spatial area at the time its object position was recorded. With this variant, the corresponding spatial area can be very well recorded by measurements based on several objects. Furthermore, falsifications of the measurements are avoided by only taking into account measurement data in which a single object was present in the spatial area. In a further embodiment, the object positions are or were recorded by optical distance measurement during the measurement accessed in step a). A tachymeter, for example, can be used for this purpose.With optical distance measurement, it may be possible to dispense with a corresponding measuring device on the respective objects and instead use an optical rangefinder set up in the room. Alternatively or additionally, the object positions can also be recorded using satellite-based positioning, with the respective objects containing a receiver for satellite signals for this purpose. Alternatively or additionally, it is also possible to record the object positions using a propagation time measurement of radio signals in the radio network. This propagation time measurement is preferably a method in which the propagation time of radio signals is measured which are received and / or transmitted by a radio device in the respective object. In a further, particularly preferred embodiment, a visualization is generated for each propagation path on a display of a user interface.The visualization reproduces the spatial area, with the course of the respective propagation path determined in step d) also being shown in the reproduced spatial area and / or the signal value determined for the respective object position in step b) and belonging to the respective propagation path being displayed in visually coded form for at least some of the object positions. This provides a user with a very intuitive understanding of the course of a corresponding propagation path. If necessary, the course or signal values ​​for multiple propagation paths can also be displayed in the visualization.P2930PC00 In a further preferred embodiment, the predetermined criterion in step b) is designed such that in a digital image of the spatial region in which the signal values ​​for all object positions of at least some of the plurality of object positions are represented as pixel values, for example as gray values, at the respective object positions, the marked object positions are identified as part of an edge by an edge extraction method. In a further variant of the method according to the invention, the predetermined criterion in step b) is designed such that those object positions of at least some of the plurality of object positions are marked for which the signal values ​​each fall below a predetermined threshold.In a further preferred embodiment of the method according to the invention, in step d) a plurality of paths are formed from the number of lines, each of which is composed of connected sections of at least a portion of the number of lines, wherein a respective path begins with a section of a line at the transmitter and ends with a section of a line at the receiver. From the plurality of paths, one path is then identified as the respective propagation path. This propagation path is preferably identified as a function of the delay value, which can be determined in step a) in addition to the number of signal values ​​for each propagation path. From the plurality of paths, the path whose path length has the smallest deviation from the length of the respective propagation path according to the associated delay value is identified as the propagation path.Using this criterion, a propagation path can be easily identified. The method according to the invention can be used in any radio 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 radio network. It is also possible for the radio network to be a UWB network (UWB = Ultra Wide Band) according to the P2930PC00 IEEE 802.15-4 standard family. Furthermore, the radio network can be a mobile radio network (e.g., 5G or 6G). In addition to the method described above, the invention relates to a device for the computer-aided determination of the course of a number of propagation paths of radio waves between a transmitter and a receiver of a radio network, the device being configured to carry out the method according to the invention or one or more preferred variants of the method according to the invention.The invention further relates to a computer program product with a program code stored on a machine-readable carrier for carrying out the method according to the invention or one or more preferred variants of the method according to the invention when the program code is executed on a computer. Furthermore, the invention relates to a computer program with a program code for carrying out the method according to the invention or one or more preferred variants of the method according to the invention when the program code is executed on a computer. Exemplary embodiments of the invention are described in detail below with reference to the attached figures. They show: Fig. 1 a schematic plan view of a spatial area with a radio network extending therein, on the basis of which an embodiment of the method according to the invention is explained; P2930PC00 Fig.Fig. 2 is a diagram illustrating a measured channel impulse response for a radio signal of the radio network from Fig. 1; Fig. 3 is a diagram illustrating the signal strength change for a propagation path from Fig. 1, taking into account the movement of the user shown in Fig. 1; Fig. 4 is a visualization of a signal attenuation map for the user movement shown in Fig. 1; Fig. 5 is a further visualization of a signal attenuation map for a different user movement from Fig. 1; Fig. 6 is a schematic plan view analogous to Fig. 1, using which a further embodiment of the method according to the invention is explained; Fig. 7 is a visualization of a signal attenuation map generated based on movements of multiple users in the spatial area; and Fig. 8 is a flowchart illustrating the essential steps of an embodiment of the method according to the invention.The variants of the method according to the invention described below are explained with reference to the spatial area R shown in Fig. 1 and in other figures, in which a radio network is installed. 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, two of these network nodes are represented by black dots as an example. The radio signal from the network node TR, which acts as the transmitter, is evaluated. This radio signal is received by the network node RE, which acts as the receiver. Independently of this, the network node TR can also receive radio signals and the network node RE can also transmit radio signals. In the embodiment described here, the P2930PC00 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). The radio network can also be a cellular network.The aim of the method described here is to determine the propagation paths of the radio waves within the spatial area R with the aid of a moving object O by evaluating the radio signals received at the receiver RE. In Fig. 1, this object is a human user moving along a trajectory L, whereby the radio signal received at the receiver RE is recorded and evaluated at the exemplary times t0, t1, t2, and t3, which correlate with object positions PO0, PO1, PO2, and PO3. The spatial area R is bounded by two walls 1 and 2 and, in addition to the network nodes TR and RE, contains 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 allows the direct propagation of the radio waves (iewithout 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 where the radio waves are scattered by the scattering object 3. In the embodiment described here, the aim is to determine the previously unknown course of the multipath propagation paths PA2, PA3 and PA4. In the following, the shape of the radio signals received at the receiver RE is first explained before the determination of the course of the propagation paths is discussed 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 P2930PC00 propagation paths.This results in a channel impulse response CIR from a received radio signal, which is a superposition of the signal components of the various propagation paths between the transmitter TR and 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. Fig. 2 shows an example of 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 ^^^^ ∙ ^^^^ (delay time multiplied by the speed of light) in meters is plotted along the abscissa, and the absolute value A of the signal amplitude (i.e. the signal strength in the form of the received signal power) is plotted along the abscissa.The corresponding signal propagation paths are indicated as peaks in the channel impulse response, with the propagation paths associated with the peaks being referenced by the reference symbols PA1 to PA4 of these paths. As expected, the direct LoS propagation path between transmitter TR and receiver RE has the signal with the highest signal strength, whereas the other propagation paths exhibit significantly lower signal strengths. The channel impulse response ℎ( ^^^^. ^^^^ , ^^^^) can at discrete times ^^^^ ^^^^ the signal detection by a finite number of N signal components corresponding to the different propagation paths can be described as follows: Here, ^^^^(∙) denotes the Dirac distribution. Each signal component corresponds to a propagation path and is determined by the time-varying propagation delay ^^^^ ^^^^ (^^^^ ^^^^ ) and the time-varying complex amplitude ^^^^ ^^^^ (^^^^^^^^ ). Here, i = 1 corresponds to the LoS propagation path, which according to Fig. 1 is the propagation path PA1. In the embodiment described here, P2930PC00 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, the following applies: ^^^^ ^^^^ ( ^^^^ ^^^^ ) = ^^^^ ^^^^.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. Within the scope of the variants of the inventive method described here, the channel impulse response CIR is measured, and from this, the amplitude ^^^^ is determined using a known channel estimation. ^^^^ ( ^^^^^^^^ ) and propagation delay ^^^^ ^^^^ for the corresponding signal component (ie the corresponding propagation path). The propagation delay only needs to be for one point in time ^^^^ ^^^^ be determined, since the network nodes are stationary. Alternatively, the propagation delay can be a time delay ^^^^ ^^^^ averaged value. From the amplitude ^^^^ ^^^^ (^^^^ ^^^^ ) the change will then be ^^�^^ ^^^^ (^^^^ ^^^^ ) of the signal strength or signal power | ^^^^ ^^^^ (^^^^ ^^^^ )| relative to the signal strength averaged over all processed measurements | ^^^^^^^^ ^^^^ ^^^^ ^^^^ | The signal strength change, or the signal strength relative to the average signal strength, is thus given as follows: In a preferred variant, the channel estimation is carried out to determine the amplitude ^^^^ ^^^^ (^^^^ ^^^^ ) and the propagation delay ^^^^ ^^^^ based on the algorithm from [2]. However, other known algorithms for channel estimation can also be used. Fig. 3 shows an example of the signal strength change determined for the scenario in Fig. 1. ^^^^ (^^^^ ^^^^) in dB for the propagation path PA2 as a function of time t. In Fig. 3, the detection times t0 to t3 are highlighted by dashed vertical lines corresponding to Fig. 1. As can be seen, a strong P2930PC00 attenuation of the signal strength occurs at time t2, at which the object or user O is just passing the propagation path PA2. The object or user therefore has a strong influence on the received signal strength. This influence is used in the method according to the invention to determine the course of the corresponding propagation paths of the radio signals in the spatial area, as will be explained in more detail below. The starting point for all embodiments described here is the above-described detection of the signal strength changes for corresponding signal components orPropagation paths by means of a channel estimation, wherein at the time the corresponding change in signal strength occurs, the position of an object in the spatial area covered by the radio network is also detected simultaneously. In the embodiment of Fig. 1, the corresponding position of an individual user O who moves along the trajectory L is tracked. The user's position can be detected in various ways. In one variant, the detection is carried out by an external measuring device that continuously records the user's position, for example optically using a tachymeter. Alternatively or additionally, it is also possible for the user's position to be detected via satellite-supported positioning using a corresponding terminal device carried by the user. The user's position can also be detected by a signal measurement within the radio network.For this purpose, the user carries a terminal device with a transmitting and receiving unit according to the radio network standard, whereby the user's position is determined by measuring the propagation time of the radio signals between the network nodes and the terminal device. In one variant (uplink), the terminal device carried by the user transmits a beacon with the transmission time encoded in it as a radio signal. The beacon is received by the network nodes, whereupon the user's position is estimated centrally in a backend computer based on the signal propagation time of the beacon to the network nodes. In another variant (downlink), the individual network nodes transmit beacons, which are received by the user's terminal device, which in turn estimates the user's position based on the signal propagation times of the beacons and then transmits the data to a central backend server.In all variants of the invention, a central backend server is used in which the user's position data is stored or estimated, and the signal strength changes are determined based on the channel impulse responses, which are measured in the receiver RE and transmitted to the backend server. The inventive determination of the course of the propagation paths preferably also takes place in the backend server, whereby another computer can also be used for this purpose, provided that the data required to determine the course of the propagation paths is transmitted to it. Fig. 4 shows a visualization of the spatial region R from Fig. 1, which is reproduced on a display of a user interface as part of an embodiment of the inventive method. The reference symbols reproduced in Fig. 4 are not part of the visualization. In the visualization of Fig.4 shows the propagation path PA2, the course of which is determined within the framework of the method according to the invention. The visualization also shows the path traveled by the user or object O along the trajectory L, wherein the signal strength changes, which were determined at respective times for corresponding positions of the user during their movement, are color-coded on the line L, which is not apparent from the black and white representation in Fig. 4. In the dashed section D, the color coding conveys that the signal strengths are attenuated, which is due to the fact that the user is on or near the propagation path PA2. Fig. 4 thus shows the signal attenuation, so that this visualization can also be understood as a signal attenuation map for the propagation path PA2. P2930PC00 Fig. 5 shows a visualization analogous to Fig.4, whereby the user's trajectory L is now considerably longer and crosses the propagation path PA2 more frequently. Along the distance L, the signal strength changes are again color-coded, with signal attenuations in Fig. 5 again being indicated by dashed sections D. As can be seen, the course of the propagation path PA2 is indicated by the positions of the individual attenuated sections D, since when the corresponding attenuations occur, the propagation path is crossed by the object or by the user O. Since in the visualization of Fig. 5 the course of the propagation path is already conveyed by the signal attenuations shown, the explicit reproduction of the propagation path can be omitted in this visualization if necessary. In the embodiment explained with reference to Fig. 1 to Fig. 5, the signal strength changes are determined for positions of an individual user O who is moving in the spatial area R.In a modified embodiment, however, it is also possible for the corresponding signal strength changes to be determined cooperatively, taking into account multiple movement trajectories of users in the corresponding spatial area. Such a cooperative approach is shown in the schematic plan view of Fig. 6, which shows the same spatial area R and the same radio network with the transmitter TR and the receiver RE as Fig. 1. The signal strength changes are determined at a plurality of times t1 to t. M and t M+1 are N In the time span from t1 to t M an object O in the form of a user along the trajectory L in the spatial region R, whereas at the later times t M+1 are Nanother object or another user O' moves along the trajectory L' in the spatial area R. Both users O and O' carry a terminal 5 with them, with which the corresponding positions of the users at the displayed times t1 to t M or t M+1 are N As described above, this position detection can be carried out, for example, using satellite-based positioning or by measuring the propagation time of beacons in the radio network. For the times t1 to t M and t M+1 are NThe signal strength changes described above in P2930PC00 are also determined by recording the channel impulse response in the receiver RE and a subsequent channel estimation. By taking into account the movement trajectories of multiple users, better coverage of the spatial area is achieved and thus a larger number of signal values ​​are recorded, which can improve the determination of the course of the propagation paths described below. Analogous to the previously described embodiment, in the case of multiple users, the corresponding signal attenuations can also be displayed in a signal attenuation map on the display of a user interface using a visualization. A corresponding visualization for the propagation path PA2 is shown in Fig. 7, whereby the reference numerals shown are not part of the visualization. According to Fig.In Figure 7, not just two, but four movement trajectories L1, L2, L3, and L4 of four users are considered. The detected signal strength changes along the movement trajectories are color-coded, with sections with attenuated signal values ​​represented by dashed sections D in the black-and-white representation of Figure 7. When recording the corresponding signal strength changes, it may happen that several users are present in the room at the same time. This leads to a falsification of the signal attenuation. Therefore, those signal values ​​for which several users were present in the room at the same time are deleted from the detected signal strength changes.In other words, when determining the course of the propagation paths and in the above visualization, only those signal strength changes are taken into account for which only a single user was present in the room. A variant of the method according to the invention is described below with reference to Fig. 8, with which the course of this propagation path can be determined from the determined signal strength changes for this propagation path. In the following, a single propagation path with a signal component corresponding to P2930PC00, obtained by channel estimation, is considered; however, the method can also be carried out for multiple signal propagation paths, taking the corresponding signal components into account.As explained above, in a first step of the method, the positions of one or more objects in the spatial domain are recorded and, at the same time, the channel impulse responses for the recorded positions are measured. In the above, the objects were users, but an object can also be any other moving unit, such as a self-driving robot. The recording or measurement of the positions and channel impulse responses can, if necessary, have already been carried out before the start of the method. In other words, step S1 does not have to be part of the method. However, access to a memory containing the recorded positions and channel impulse responses must be guaranteed. As explained above, the positions along a movement trajectory of a single object can be recorded (see Fig. 1). Alternatively, the positions along the movement trajectories of multiple objects can also be taken into account (see Fig. 6).In a step S2, the signal strength changes ^^�^^ are determined from the channel impulse responses for the considered propagation path. ^^^^ ( ^^^^ ^^^^ ) for the corresponding object positions and the delay time ^^^^ ^^^^determined using a channel estimate. In an optional step S3, the signal attenuation resulting from the signal strength changes due to the existing users can be visualized in a signal attenuation map on the display DI of a user interface UI, as described above with reference to Fig. 4, Fig. 5 and Fig. 7. If necessary, the signal attenuation map can also be visualized at the end of the method, in which case the determined course of the propagation path can also be reproduced in the signal attenuation map. Finally, in a step S4, a map MA of the spatial area R under consideration is determined. In this map MA, those object positions are marked for which the signal strength changes determined in step S2 are below a predetermined threshold and thus represent attenuated radio signals that occur when a user crosses the corresponding propagation path.The map does not have to be visualized, but can simply be represented by digital data. The map MA can be viewed as a binary representation of the signal attenuation map explained above. The marked positions in the map MA can, if necessary, also be determined in a way other than by comparison with a predetermined threshold. In particular, an edge detection method can be carried out in a digital image of the spatial region in which the determined signal strength changes are represented by pixel values ​​at corresponding positions of the moving object(s). An object position is marked if, according to the result of the edge detection method, it belongs to a detected edge. The corresponding digital image does not have to be visualized, but can simply be represented by digital data from object positions with assigned pixel values.Finally, in step S5, the lines present in the map MA are extracted using a known Hough transformation. The Hough transformation is an efficient and robust method for detecting lines (i.e., straight lines) in image data. The Hough transformation is based on a straight line representation in the Hessian normal form, which describes a line by its distance from the coordinate origin of the image coordinate system and the angle of the normal vector on the line. The angle of the normal vector is discretized within the Hough transformation.For each marked position with a two-dimensional coordinate (x, y) in the map MA and all discrete angles ^^^^, the distance ^^^^ of a corresponding line to the coordinate origin is calculated using the following formula: ^^^^ = ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ + ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ P2930PC00 The angle ^^^^ and the distance ^^^^ span the coordinate system of an output image, which represents the Hough transformation. Initially, all pixels in the output image have the value zero. As part of the Hough transformation, pairs of angles and distances are calculated for each marked position in the map MA using the equation above, and the pixels in the output image belonging to the pairs are incremented by one. The result of the Hough transformation can be visualized as a grayscale image in which the x-axis represents the distance ^^^^ and the y-axis the angle ^^^^ of a potential line, and the gray levels orPixel values ​​of the pixels of the grayscale image represent the set of marked positions from the map MA that lie on the potential line. A line is recognized if the pixel value of the corresponding pixel in the grayscale image meets a threshold criterion. In the embodiment described here, the threshold criterion is given by the N. H Pixels with the largest pixel values ​​in the grayscale image of the Hough transform are identified as lines. This results in a set ^^^^ = of possible lines that describe a propagation path. In the subsequent step S6, the extracted lines are then pieced together in such a way that a propagation path results. The following describes the method for obtaining this propagation path. First, a first subset ^^^^ ^^^^ ^^^^of lines are extracted from the set ^^^^ of lines. All lines of this subset begin in the sender TR. Furthermore, a second subset ^^^^ ^^^^ ^^^^ of lines are extracted from the set ^^^^ of lines. All lines in this subset end at the receiver RE. Subsequently, a set P is determined from all paths composed of consecutive sections of the above set ^^^^ of lines and satisfying the condition that the path coincides with a line passing through the sender TR, i.e., from the subset ^^^^ ^^^^ ^^^^ , P2930PC00 begins and with a line running through the receiver RE, ie from the subset ^^^^ ^^^^ ^^^^ , ends. Furthermore, only paths that do not exceed a maximum number of reflections are considered. This maximum number may be at most as large as the total number of lines from the above set ^^^^ plus the value 1 and minus the total number of lines belonging to the subsets ^^^^ ^^^^ ^^^^and ^^^^ ^^^^ ^^^^ Furthermore, the line segments contained in each path may only be traversed once between sender TR and receiver RE. For all paths in the set P, the set D of the corresponding path lengths ^^^^ ^^^^ in the spatial region R. Mathematically, the determination of the set P of paths can be described as follows: A set P of paths with the corresponding path lengths ^^^^ ^^^^ determined, where a respective path from the set P satisfies the following condition: - A path ^^^^ ∈ ^^^^ is a sequence of ^^^^ ^^^^ Lines, ie using tuple notation, ^^^^ = { ^^^^1, … , ^^^^ ^^^^ ^^^^}, where ^^^^ ^^^^ ∈ ^^^^. - The first section of a path is on a line ^^^^1∈ ^^^^ ^^^^ ^^^^, which begins at the location of the transmitter TR and ends at an intersection point between the lines ^^^^1 and ^^^^2. - For double reflections or higher-order reflections, the m-th intermediate section of the path is on a line ^^^^ ^^^^ ∈ ^^^^ ^^^^ = ^^^^\ ^^^^ ^^^^ ^^^^ ∪ ^^^^ ^^^^ ^^^^ , which is at an intersection point between ^^^^ ^^^^−1 and ^^^^ ^^^^ begins and ends at an intersection point between ^^^^ ^^^^ and ^^^^ ^^^^+1, where ^^^^ ∈ ] 1, ^^^^ ^^^^ [ gilt. - The last section of the path is on a line ^^^^ ^^^^ ^^^^ ∈ ^^^^ ^^^^ ^^^^ , which is at the intersection point between ^^^^^^^^ ^^^^−1and ^^^^ ^^^^ ^^^^ begins and ends at the location of the receiver RE. - Each line of the path is traversed only once, thus limiting the maximum possible number ^^^^^^^^ ^^^^ ^^^^of reflections by the cardinality of ^^^^ ^^^^ is bounded, ie ^^^^^^^^ ^^^^ ^^^^≤ | ^^^^ ^^^^| + 1. Optionally, a maximum number of reflections can be specified in advance, ie ^^^^^^^^ ^^^^ ^^^^≤ min {| ^^^^ ^^^^ | + 1, ^^^^^^^^ ^^^^ ^^^^}. P2930PC00 Algorithmically, the determination of the set P of paths with assigned path lengths can be implemented, for example, based on the following pseudocode: Input: Set of lines by transmitter TR: ^^^^ ^^^^ ^^^^ Number of lines by receiver RE: ^^^^ ^^^^ ^^^^ Number of remaining lines: ^^^^ ^^^^ Maximum reflection order: ^^^^^^^^ ^^^^ ^^^^= min{| ^^^^ ^^^^ | + 1, ^^^^^^^^ ^^^^ ^^^^} Output: Set of potential propagation paths: ^^^^ Set of corresponding path lengths: ^^^^ for ^^^^ ^^^^ ∈ ^^^^ ^^^^ ^^^^ do for ^^^^ ^^^^ ∈ ^^^^ ^^^^ ^^^^ do for ^^^^ = 1: ^^^^^^^^ ^^^^ ^^^^do if ^^^^ = 1 then add path ^^^^ =� ^^^^ ^^^^ , {}, ^^^^ ^^^^ � to ^^^^ add else Calculate the quantity ^^^ ^ ^ ^^^all variations without repetition of ^^^^ − 1 lines ^^^^ ∈ ^^^^ ^^^^ Add paths ^^^^ =� ^^^^ ^^^^ , ^^^^, ^^^^ ^^^^ � ^^^^ ^^^^ ^^^^ added, ∀ ^^^^ ∈ ^^^^ ^^^^ Calculate path length ^^^^ ^^^^ of the path ^^^^ by summing the distances between successive intersection points along the path ^^^^ from the transmitter TR to the receiver RE Add path length ^^^^ ^^^^ to ^^^^ add endif endfor endfor endfor In a next step, the differences between the path lengths of the determined paths and the propagation distance ^^^^ ^^^^= ^^^^ ∙ ^^^^ according to the P2930PC00 propagation delay ^^^^ of the considered propagation path. The propagation delay comes from the channel estimation described above. Finally, the path from the set P is determined as the propagation path with the smallest difference to the propagation distance. Ideally, this difference should be zero. However, due to measurement noise and estimation errors, the difference is usually always greater than zero. Nevertheless, the path with the smallest difference to the propagation distance is usually the path that corresponds to the actual propagation path. To ensure that no incorrect path is selected, paths with differences between path length and propagation distance above a threshold are deleted from the set P in advance. The final result is the corresponding propagation path with its course between transmitter and receiver.In general, the method described above does not require any prior information about the spatial area, such as floor plans. However, additional information about the spatial area can be easily integrated into the method and improve the process of selecting the appropriate path as the propagation path. The embodiments of the invention described above have a number of advantages. In particular, for the first time, a method is created with which the course of propagation paths of radio waves between a transmitter and a receiver in a spatial area can be determined by evaluating radio signals in a radio network. For this purpose, radio signals are detected while an object is moving in the spatial area, and the course of the propagation paths is determined from the signal attenuation caused by the object.The information about the course of the propagation paths can be used in the context of passive localization, which takes multipath propagation paths into account. Such passive localization is disclosed, for example, in the above-mentioned publication [1]. Furthermore, the knowledge about the course of the propagation paths can be used to obtain information about the geometry of the spatial region.

[0002] P2930PC00 References: [1] 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 [2] 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

Claims

P2930PC00 Patent claims 1. Method for the computer-aided determination of the course of a number of propagation paths (PA1, PA2, PA3, PA4) of radio waves between a transmitter (TR) and a receiver (RE) of a radio network, wherein the radio network covers a spatial area (R) and a respective propagation path (PA1, PA2, PA3, PA4) represents a transmission path of the radio waves of the radio network in the spatial area (R) between the transmitter (TR) and the receiver (RE), wherein: a) signal values ​​( ^^�^^ ^^^^ ( ^^^^ ^^^^ ) ) are determined by accessing a performed or completed measurement, in which for one or more objects (O, O') moving in the spatial area (R), a plurality of object positions (PO0, PO1, PO2, PO3) are recorded in combination with respective radio signals of the radio network, whereby the signal values ​​( ^^�^^ ^^^^ ( ^^^^ ^^^^ ) ) a number of signal values ​​( ^^�^^ ^^^^( ^^^^ ^^^^ ) ) for a respective object position (PO0, PO1, PO2, PO3), where a respective signal value ( ^^�^^ ^^^^ (^^^^ ^^^^ )) the number of signal values ​​( ^^�^^ ^^^^ (^^^^ ^^^^ )) belongs to a propagation path (PA1, PA2, PA3, PA4) and is a signal strength measure of the radio waves which are received at the receiver (RE) on this propagation path (PA1, PA2, PA3, PA4) at the time of detection of the respective object position (PO0, PO1, PO2, PO3); b) for a respective propagation path (PA1, PA2, PA3, PA4), a map (MA) of the spatial area (R) is determined, in which map object positions (PO0, PO1, PO2, PO3) from at least some of the plurality of object positions (PO0, PO1, PO2, PO3) are marked, wherein for a marked object position, the signal value ( ^^�^^) belonging to the respective propagation path (PA1, PA2, PA3, PA4) ^^^^ (^^^^ ^^^^)) according to a predetermined criterion compared to an average value of the signal values ​​belonging to the respective propagation path (PA1, PA2, PA3, PA4) ( ^^�^^ ^^^^ (^^^^ ^^^^ )) is damped over all object positions (PO0, PO1, PO2, PO3) of at least a part of the plurality of object positions (PO0, PO1, PO2, PO3); P2930PC00 c) from the map (MA) determined for the respective propagation path (PO0, PO1, PO2, PO3), a number of lines (g i ) is extracted along which the marked object positions (PO0, PO1, PO2, PO3) extend in the spatial area (R); d) from the number of lines (g i ) the course of the respective propagation path (PA1, PA2, PA3, PA4) is determined, wherein the course consists of one or more connected sections of at least a part of the number of lines (g i) 2. Method according to claim 1, characterized in that in step a) in addition to the number of signal values ​​( ^^�^^ ^^^^ (^^^^ ^^^^ )) a number of delay values ​​( ^^^^ ^^^^ ) is determined, whereby a respective delay value ( ^^^^ ^^^^) belongs to a propagation path (PA1, PA2, PA3, PA4) and is a measure of the transmission duration of the radio waves on this propagation path (PA1, PA2, PA3, PA4) from the transmitter (TR) to the receiver (RE).

3. Method according to claim 1 or 2, characterized in that, in the measurement accessed in step a), a plurality of object positions (PO0, PO1, PO2, PO3) of a single object (O) moving in the spatial area (R) are detected. 4.Method according to claim 1 or 2, characterized in that in the measurement accessed in step a), a plurality of object positions (PO0, PO1, PO2, PO3) of a plurality of objects (O, O') which move in the spatial area (R) are detected, wherein the at least part of the plurality of object positions (PO0, PO1, PO2, PO3) contains only those object positions (PO0, PO1, PO2, PO3) which each belong to an object (O, O') which was the only object in the spatial area (R) at the time of detecting its object position. P2930PC00 5. Method according to one of the preceding claims, characterized in that in the measurement accessed in step a), the object positions (PO0, PO1, PO2, PO3) are detected by optical distance measurement and / or via satellite-based positioning and / or via a propagation time measurement of radio signals in the radio network.

6. Method according to one of the preceding claims, characterized in that for a respective propagation path (PA1, PA2, PA3, PA4), a visualization is generated on a display (DI) of a user interface (UI), wherein the spatial area (R) is reproduced in the visualization, wherein furthermore in the reproduced spatial area (R) the course of the respective propagation path (PA1, PA2, PA3, PA4) determined in step d) is displayed and / or for at least some of the object positions (PO0, PO1, PO2, PO3), the determined signal value ( ^^�^^ ^^^^ (^^^^ ^^^^)) is displayed in visually coded form, which belongs to the respective propagation path (PA1, PA2, PA3, PA4).

7. Method according to one of the preceding claims, characterized in that the predetermined criterion in step b) is designed such that in a digital image of the spatial region (R) in which the signal values ​​( ^^�^^ ^^^^ (^^^^ ^^^^)) for all object positions (PO0, PO1, PO2, PO3) of at least one part of the plurality of object positions (PO0, PO1, PO2, PO3) are represented as pixel values ​​at the respective object positions (PO0, PO1, PO2, PO3), the marked object positions are identified as part of an edge by an edge extraction method.

8. Method according to one of claims 1 to 6, characterized in that the predetermined criterion in step b) is designed such that those object positions (PO0, PO1, PO2, PO3) of at least one part of the plurality of object positions (PO0, PO1, PO2, PO3) are marked for which the signal values ​​( ^^�^^ ^^^^ (^^^^ ^^^^ )) each fall below a predetermined threshold. P2930PC00 9. Method according to one of the preceding claims, characterized in that the number of lines (g i) is extracted by means of a Hough transformation.

10. Method according to one of the preceding claims, characterized in that in step d) from the number of lines (g i ) a plurality of paths is formed, each of which consists of connected sections of at least a part of the number of lines (g i), wherein a respective path (P) begins with a section of a line at the transmitter (TR) and ends with a section of a line at the receiver (RE), wherein one path from the plurality of paths is identified as the respective propagation path (PA1, PA2, PA3, PA4).

11. The method according to claim 10 in combination with claim 2, characterized in that from the plurality of paths, that path is identified as the respective propagation path (PA1, PA2, PA3, PA4) whose path length has the smallest deviation from the length of the respective propagation path (PA1, PA2, PA3, PA4) according to the delay value (^^^^) associated with it. ^^^^).

12. Method according to one of the preceding claims, characterized in that the radio network is a WLAN network or a UWB network or a mobile radio network.

13. Device for the computer-assisted determination of the course of a number of propagation paths (PA1, PA2, PA3, PA4) of radio waves between a transmitter (TR) and a receiver (RE) of a radio network, wherein the radio network covers a spatial area (R) and a respective propagation path (PA1, PA2, PA3, PA4) represents a transmission path of the radio waves of the radio network in the spatial area (R) between the transmitter (TR) and the receiver (RE). P2930PC00, wherein the device is designed to carry out a method in which: a) signal values ​​( by accessing a measurement that has been carried out or completed, in which a plurality of object positions (PO0, PO1, PO2, PO3) are recorded in combination with the respective radio signals of the radio network for one or more objects (O, O') moving in the spatial area (R), whereby the signal values ​​( ^^�^^ ^^^^ ( ^^^^ ^^^^ ) ) a number of signal values ​​( ^^�^^ ^^^^ ( ^^^^ ^^^^ ) ) for a respective object position (PO0, PO1, PO2, PO3), where a respective signal value ( ^^�^^ ^^^^ (^^^^ ^^^^ )) the number of signal values ​​( ^^�^^ ^^^^ (^^^^ ^^^^)) belongs to a propagation path (PA1, PA2, PA3, PA4) and is a signal strength measure of the radio waves which are received at the receiver (RE) on this propagation path (PA1, PA2, PA3, PA4) at the time of detection of the respective object position (PO0, PO1, PO2, PO3); b) for a respective propagation path (PA1, PA2, PA3, PA4), a map (MA) of the spatial area (R) is determined, in which map object positions (PO0, PO1, PO2, PO3) from at least some of the plurality of object positions (PO0, PO1, PO2, PO3) are marked, wherein for a marked object position, the signal value ( ^^�^^) belonging to the respective propagation path (PA1, PA2, PA3, PA4) ^^^^ ( ^^^^ ^^^^ ) ) according to a predetermined criterion compared to an average of the signal values ​​( ^^�^^) belonging to the respective propagation path (PA1, PA2, PA3, PA4) ^^^^ (^^^^ ^^^^)) is attenuated over all object positions (PO0, PO1, PO2, PO3) of at least one part of the plurality of object positions (PO0, PO1, PO2, PO3); c) from the map (MA) determined for the respective propagation path (PO0, PO1, PO2, PO3), a number of lines (g i ) is extracted along which the marked object positions (PO0, PO1, PO2, PO3) extend in the spatial area (R); d) from the number of lines (g i ) the course of the respective propagation path (PA1, PA2, PA3, PA4) is determined, whereby the course is P2930PC00 one or more contiguous sections of at least a part of the number of lines (g i) 14. Device according to claim 13, characterized in that the device is set up to carry out a method according to one of claims 2 to 12.

15. Computer program product with a program code stored on a machine-readable carrier for carrying out a method according to one of claims 1 to 12 when the program code is executed on a computer.

16. Computer program with a program code for carrying out a method according to one of claims 1 to 12 when the program code is executed on a computer.

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