Fresnel zone-based tracking method and device, electronic device, and storage medium

Abstract

The application provides a tracking method and device based on a Fresnel region, electronic equipment and a storage medium, comprising: determining a target moving speed of a passive target based on frequency domain channel estimation information; taking a plurality of grids in an environmental coordinate system as initial positions, and constructing candidate motion trajectories based on the target moving speed at a plurality of observation times; for each candidate motion trajectory, and a PDP observation ratio of the observation time corresponding to each coordinate position in the candidate motion trajectory, determining an energy hot spot trajectory diagram; for each candidate motion trajectory, judging whether the energy hot spot trajectory diagram corresponding to the candidate motion trajectory matches a signal strength hot spot diagram corresponding to the environmental coordinate system, and taking the candidate motion trajectory corresponding to the energy hot spot trajectory diagram matched with the signal strength hot spot diagram as a tracking result of the passive target. The application realizes accurate tracking and positioning of the passive target.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wireless positioning technology, in particular to a tracking method and device based on Fresnel zone, electronic equipment and computer readable storage medium. BACKGROUND

[0002] An important development direction of next-generation wireless communication technology is the integration of communication, sensing and radar, and future Wi-Fi signals will not only have the function of data transmission, but also have the function of sensing passive targets. Passive targets refer to people or other targets that do not carry terminal devices. Passive targets will affect the indoor Wi-Fi signal during movement in an indoor environment, causing changes in the multipath channel of the Wi-Fi signal. With this principle, passive targets in the indoor environment can be tracked and located. SUMMARY

[0003] The purpose of the embodiments of the present application is to provide a tracking method and device based on Fresnel zone, electronic equipment and computer readable storage medium, for realizing accurate tracking and positioning of passive targets.

[0004] In one aspect, the present application provides a tracking method based on Fresnel zone, applied to a Wi-Fi transceiver system, the Wi-Fi transceiver system including a transmitter, a first receiver and a second receiver, comprising:

[0005] Based on the frequency domain channel estimation information corresponding to each receiver, determining the target moving speed of the passive target relative to the Wi-Fi transceiver system;

[0006] Taking a plurality of grids in an environmental coordinate system as initial positions, based on the target moving speed at a plurality of observation times, constructing a candidate motion trajectory corresponding to each initial position; wherein each candidate motion trajectory includes a plurality of coordinate positions;

[0007] For each candidate motion trajectory, and the PDP observation ratio of the observation time corresponding to each coordinate position in the candidate motion trajectory, determining the energy hotspot trajectory graph corresponding to the candidate motion trajectory;

[0008] According to the first position information of the first receiver, the second position information of the second receiver, the power of the transmitter and the third position information of the transmitter, generating a signal strength hotspot graph corresponding to the environmental coordinate system based on the principle of Fresnel zone;

[0009] For each candidate motion trajectory, determining whether the energy hotspot trajectory graph corresponding to the candidate motion trajectory matches the signal strength hotspot graph, and taking the candidate motion trajectory corresponding to the energy hotspot trajectory graph matching the signal strength hotspot graph as the tracking result of the passive target.

[0010] In an embodiment, the determining the target moving speed of the passive target relative to the Wi-Fi transceiving system based on the frequency domain channel estimation information corresponding to each receiver comprises:

[0011] cleaning the frequency domain channel estimation information corresponding to each receiver, and determining a multipath channel fading factor corresponding to the cleaned frequency domain channel estimation information;

[0012] determining a Doppler shift corresponding to the multipath channel fading factor in a Gaussian Doppler function for the multipath channel fading factor corresponding to each receiver;

[0013] converting the Doppler shift corresponding to each receiver into an observed speed of the passive target relative to the receiver;

[0014] combining the observed speed corresponding to the first receiver and the observed speed corresponding to the second receiver into the target moving speed.

[0015] In an embodiment, the cleaning the frequency domain channel estimation information corresponding to each receiver, and determining a multipath channel fading factor corresponding to the cleaned frequency domain channel estimation information comprises:

[0016] converting the frequency domain channel estimation information corresponding to each receiver into a time domain channel impulse response, and determining a power delay profile based on the time domain channel impulse response;

[0017] copying and splicing the power delay profile to obtain a specified power delay profile; wherein the specified power delay profile includes powers of a plurality of sampling points;

[0018] sliding a search window in the specified power delay profile with a preset window length, searching for a maximum power sum in the window, and taking a plurality of window-in sampling points corresponding to the maximum power sum as sampling points corresponding to an effective channel;

[0019] setting the power of a first window-in sampling point from left to right in the plurality of window-in sampling points to zero, and calculating a power sum of the plurality of window-in sampling points;

[0020] based on the indexes of the sampling points corresponding to the effective channel, retaining time domain channel estimation values of the sampling points corresponding to the effective channel in the time domain channel impulse response, and setting time domain channel estimation values of other sampling points to zero to obtain a denoised time domain channel impulse response;

[0021] setting a first non-zero sampling point in the denoised time domain channel impulse response to zero to obtain a cleaned time domain channel impulse response;

[0022] conjugate multiplying the cleaned time domain channel impulse responses corresponding to two symbols in the same data packet to obtain a correlation power value;

[0023] dividing the relevant power value by the power sum to obtain a multipath channel fading factor.

[0024] In an embodiment, before the step of determining the energy hot spot trajectory graph corresponding to each candidate motion trajectory, the method further comprises:

[0025] determining a power sum of the NLOS channel at each observation time;

[0026] normalizing the power sum at each observation time based on the power sum at the observation time corresponding to the initial position to obtain the PDP observation ratio at the observation time corresponding to each coordinate position in the candidate motion trajectory.

[0027] In an embodiment, before the step of determining whether the energy hot spot trajectory graph corresponding to each candidate motion trajectory matches the signal strength hot spot graph, the method further comprises:

[0028] filtering out candidate motion trajectories that exceed a specified boundary range in the environment coordinate system from a plurality of candidate motion trajectories.

[0029] In an embodiment, the candidate motion trajectory corresponding to the energy hot spot trajectory graph that matches the signal strength hot spot graph is taken as the tracking result of the passive target, comprising:

[0030] When the number of observation times reaches a preset number threshold, if a plurality of candidate motion trajectories are screened out, any candidate motion trajectory is selected from the plurality of candidate motion trajectories as the tracking result of the passive target.

[0031] In an embodiment, the candidate motion trajectory corresponding to the energy hot spot trajectory graph that matches the signal strength hot spot graph is taken as the tracking result of the passive target, comprising:

[0032] When the number of observation times reaches a preset number threshold, if a plurality of candidate motion trajectories are screened out, the plurality of candidate motion trajectories are merged, and the merged motion trajectory is taken as the tracking result of the passive target.

[0033] On the other hand, the application provides a tracking device based on a Fresnel zone, applied to a Wi-Fi transceiver system, the Wi-Fi transceiver system comprising a transmitter, a first receiver and a second receiver, comprising:

[0034] a first determining module, configured to determine a target moving speed of the passive target relative to the Wi-Fi transceiving system based on frequency domain channel estimation information corresponding to each receiver;

[0035] a constructing module, configured to construct a candidate motion trajectory corresponding to each initial position based on the target moving speed at multiple observation time points, with multiple grids in an environment coordinate system as the initial positions; each candidate motion trajectory includes multiple coordinate positions;

[0036] a second determining module, configured to determine an energy hot spot trajectory corresponding to each candidate motion trajectory based on a PDP observation ratio at the observation time point corresponding to each coordinate position in the candidate motion trajectory;

[0037] a generating module, configured to generate a signal strength hot spot map corresponding to the environment coordinate system according to the first position information of the first receiver, the second position information of the second receiver, the power of the transmitter and the third position information of the transmitter based on the principle of Fresnel region;

[0038] a tracking module, configured to determine whether the energy hot spot trajectory corresponding to each candidate motion trajectory matches the signal strength hot spot map, and take the candidate motion trajectory corresponding to the energy hot spot trajectory matching the signal strength hot spot map as a tracking result of the passive target.

[0039] Further, the present application provides an electronic device, which comprises:

[0040] a processor;

[0041] a memory for storing processor-executable instructions;

[0042] wherein the processor is configured to execute the above-mentioned Fresnel region-based tracking method.

[0043] In addition, the present application provides a computer-readable storage medium, which stores a computer program executable by a processor to complete the above-mentioned Fresnel region-based tracking method.

[0044] The signal strength hot spot map generated based on the principle of Fresnel region can represent the signal strength at each position in the indoor environment, and after multiple candidate motion trajectories are generated, the actual motion trajectory of the passive target can be determined by comparing the energy hot spot trajectory corresponding to the candidate motion trajectory with the signal strength hot spot map, so as to realize accurate tracking and positioning of the passive target. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced.

[0046] Figure 1 A structural schematic diagram of an electronic device provided by an embodiment of the present application is shown in the figure.

[0047] Figure 2 A flowchart of a tracking method based on a Fresnel region provided by an embodiment of the present application is shown in the figure.

[0048] Figure 3 A schematic diagram of an environmental coordinate system provided by an embodiment of the present application is shown in the figure.

[0049] Figure 4 A schematic diagram of a Fresnel region provided by an embodiment of the present application is shown in the figure.

[0050] Figure 5 A schematic diagram of a tracking method provided by an embodiment of the present application is shown in the figure. Figure 2 A detailed flowchart of step 210 in the method is shown in the figure.

[0051] Figure 6 A schematic diagram of determining a target moving speed provided by an embodiment of the present application is shown in the figure.

[0052] Figure 7 A flowchart of a method for determining a multipath channel fading factor provided by an embodiment of the present application is shown in the figure.

[0053] Figure 8 A schematic diagram of a power-time delay spectrum provided by an embodiment of the present application is shown in the figure.

[0054] Figure 9 A schematic diagram of a power-time delay spectrum provided by an embodiment of the present application is shown in the figure. Figure 8 A schematic diagram of a specified power-time delay spectrum spliced by the power-time delay spectrum provided by an embodiment of the present application is shown in the figure.

[0055] Figure 10 A block diagram of a tracking device based on a Fresnel region provided by an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

[0057] Similar labels and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. Meanwhile, in the description of the present application, the terms "first", "second", etc. are only used for distinguishing description, and cannot be understood as indicating or implying relative importance.

[0058] As shown in the figure, Figure 1As shown, the embodiment provides an electronic device 1, comprising at least one processor 11 and a memory 12, Figure 1 The processor 11 and the memory 12 are connected through a bus 10. The memory 12 stores instructions executable by the processor 11. The instructions are executed by the processor 11 to enable the electronic device 1 to perform all or part of the processes of the method in the embodiments described below. In an embodiment, the electronic device 1 can be a computing device in a Wi-Fi transceiver system, which can be a transmitter or a receiver in the Wi-Fi transceiver system, or a device interfacing with the transmitter and the receiver, for performing the tracking method based on the Fresnel region.

[0059] The memory 12 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk or optical disk.

[0060] The present application also provides a computer-readable storage medium, which stores a computer program executable by the processor 11 to complete the tracking method based on the Fresnel region provided by the present application.

[0061] Referring to Figure 2 The flowchart of the tracking method based on the Fresnel region provided by an embodiment of the present application is shown in FIG. 2. Figure 2 As shown, the method can include the following steps 210-250.

[0062] Step 210: determining the target moving speed of the passive target relative to the Wi-Fi transceiver system based on the frequency domain channel estimation information corresponding to each receiver.

[0063] The scheme is applied to a Wi-Fi transceiving system, which comprises a transmitter, a first receiver and a second receiver. The transmitter is configured to transmit a Wi-Fi signal, and the first receiver and the second receiver are configured to receive the Wi-Fi signal. During the transceiving process of the Wi-Fi signal, the electronic device can obtain frequency domain channel estimation information from the data pilot signals received by the first receiver and the second receiver respectively through a channel estimation algorithm. The frequency domain channel estimation information comprises frequency domain channel estimation values corresponding to multiple sampling points. In an embodiment, in order to facilitate subsequent processing, the frequency domain channel estimation information can be windowed by a window function (for example, a Hamming window), so that the spectrum leakage is more concentrated.

[0064] The electronic device can determine the target moving speed of the passive target relative to the Wi-Fi transceiving system based on the frequency domain channel estimation information corresponding to the first receiver and the frequency domain channel estimation information corresponding to the second receiver.

[0065] At each observation time, the current target moving speed of the passive target can be determined, so that multiple target moving speeds corresponding to multiple continuous observation times can be obtained. Here, the interval between adjacent observation times can be configured as needed. For example, each data packet in the Wi-Fi signal corresponds to an observation time.

[0066] Step 220: Taking multiple grids in the environmental coordinate system as initial positions, constructing candidate motion trajectories corresponding to each initial position based on the target moving speeds at multiple observation times; each candidate motion trajectory comprises multiple coordinate positions.

[0067] The environmental coordinate system is a coordinate system established in the indoor environment to which the present application is applied. The environmental coordinate system can be determined based on the positions of the transmitter, the first receiver and the second receiver. The horizontal coordinate and the vertical coordinate of the environmental coordinate system can be divided by a preset interval, thereby obtaining multiple grids. Here, the interval can be configured as needed. For example, the interval can be 5 cm, 10 cm or any other interval.

[0068] The electronic device can take each grid in the environmental coordinate system as an initial position, determine the coordinate positions moved after multiple observation times based on the target moving speeds at the multiple observation times and the time interval between each two observation times. For each initial position, the coordinate positions moved after multiple observation times are obtained starting from the initial position, and a candidate motion trajectory can be constructed based on the multiple coordinate positions. Here, the candidate motion trajectory refers to a motion trajectory that can be performed by the passive target.

[0069] Referring to Figure 3 FIG. 1 is a schematic diagram of an environmental coordinate system provided by an embodiment of the present application, Figure 3One case of the initial position is shown, at time t1, the passive target is located in the middle of the grid in the environment coordinate system, and the target moving speed is determined at time t1. At the second observation time t2, according to the target moving speed (including the speed direction and the speed size) and the time difference from t2 to t1, the displacement between t1 and t2 can be calculated. On the basis of the initial position, add this displacement, the coordinate position corresponding to t2 can be obtained. According to the target moving speed at each observation time, the coordinate position corresponding to each observation time can be obtained by gradually superimposing on the coordinate position corresponding to the previous observation time, and then the motion trajectory can be constructed by a plurality of coordinate positions.

[0070] After experiencing N observation times, the motion trajectory including coordinate positions (x0, y0), (x1, y1) … (xN-1, yN-1) and (xN, yN) can be obtained with (x0, y0) as the initial position. N-1 , y N-1 ), (x N , y N ).

[0071] Step 230: For each candidate motion trajectory, and the PDP observation ratio of each coordinate position corresponding to the observation time in the candidate motion trajectory, the energy hotspot trajectory diagram corresponding to the candidate motion trajectory is determined.

[0072] The PDP observation ratio can represent the strength of the Wi-Fi signal.

[0073] Each observation time corresponds to a PDP observation ratio, and the PDP observation ratios corresponding to multiple observation times can form a PDP observation ratio sequence.

[0074] For each candidate motion trajectory, based on each coordinate position in the candidate motion trajectory and the PDP observation ratio of each coordinate position corresponding to the observation time, the energy hotspot trajectory diagram corresponding to the candidate motion trajectory can be constructed. Exemplarily, M candidate motion trajectories can be respectively constructed with the same PDP observation ratio sequence to form M energy hotspot trajectory diagrams. The energy hotspot trajectory diagram is used to represent the strength distribution of the Wi-Fi signal at each position of the candidate motion trajectory.

[0075] Step 240: According to the first position information of the first receiver, the second position information of the second receiver, the power of the transmitter and the third position information of the transmitter, the signal strength hotspot diagram corresponding to the environment coordinate system is generated according to the principle of Fresnel zone.

[0076] Here, the first position information is the coordinate position of the first receiver in the environment coordinate system; the second position information is the coordinate position of the second receiver in the environment coordinate system; and the third position information is the coordinate position of the transmitter in the environment coordinate system.

[0077] Given the known power of the Wi-Fi signal emitted by the transmitter, the electronic device can generate a signal strength heatmap corresponding to the environmental coordinate system based on the Fresnel zone principle, the first location information, the second location information, the third location information, and the power. This signal strength heatmap can characterize the intensity distribution of the Wi-Fi signal at various locations in the environmental coordinate system.

[0078] Reference Figure 4 This is a schematic diagram of the Fresnel zone provided in an embodiment of this application, as shown below. Figure 4 As shown, the arcs represent the peak positions of the signal strength, and the areas between the arcs represent the trough positions of the signal strength. The closer the signal is to the first receiver (RX1), the second receiver (RX2), and the transmitter (TX), the stronger the signal strength. Based on the generated Fresnel zones, the signal strength of each grid in the environmental coordinate system can be determined.

[0079] Step 250: For each candidate motion trajectory, determine whether the energy hotspot trajectory map corresponding to the candidate motion trajectory matches the signal intensity hotspot map. The candidate motion trajectory corresponding to the energy hotspot trajectory map that matches the signal intensity hotspot map is taken as the tracking result of the passive target.

[0080] Electronic devices can determine whether the signal intensity distribution represented by the energy hotspot trajectory map corresponding to each candidate motion trajectory matches the signal intensity distribution represented by the signal intensity heatmap. For example, the electronic device can check whether the difference between the signal intensity at each position in the energy hotspot trajectory map and the actual signal intensity at each position in the signal intensity heatmap is less than a preset threshold. If the difference is less than the preset threshold, the signal intensity at that position can be considered a match. If the signal intensity at all positions in an energy hotspot trajectory map matches the signal intensity heatmap, then the energy hotspot trajectory map matches the signal intensity heatmap. If the signal intensity at several positions in an energy hotspot trajectory map does not match the signal intensity heatmap, then the energy hotspot trajectory map does not match the signal intensity heatmap.

[0081] After matching the energy hotspot trajectory maps of multiple candidate motion trajectories with the signal intensity hotspot maps, several candidate motion trajectory maps can be selected. Electronic devices can use the selected candidate motion trajectory maps as the tracking results of passive targets, and the tracking results characterize the motion of passive targets.

[0082] During the execution of this application's scheme, the number of observation times gradually increases over time, resulting in a gradual increase in candidate motion trajectories. The electronic equipment can execute steps 210 to 250 as described above at each observation time. The more observation times there are, the more accurate the final tracking result will be.

[0083] Through the above measures, the signal intensity hot spot map generated by the Fresnel region principle can represent the signal intensity of each position in the indoor environment. After generating a plurality of candidate motion trajectories, the actual motion trajectory of the passive target can be determined by comparing the energy hot spot trajectory corresponding to the candidate motion trajectory and the signal intensity hot spot map, so as to realize accurate tracking and positioning of the passive target.

[0084] In an embodiment, referring to Figure 5 For an embodiment of the present application Figure 2 The detailed flowchart of step 210 in the embodiment is shown in FIG. 2B. Figure 5 During the execution of step 210, the following steps 211 to 214 can be executed.

[0085] Step 211: clean the frequency domain channel estimation information corresponding to each receiver, and determine the multipath channel fading factor corresponding to the cleaned frequency domain channel estimation information.

[0086] The electronic device can clean the frequency domain channel estimation information corresponding to each receiver, remove the data of the LOS (Line of Sight) channel and noise, obtain the cleaned frequency domain channel estimation information, and further determine the multipath channel fading factor corresponding to the cleaned frequency domain channel estimation information.

[0087] The electronic device can determine the multipath channel fading factor corresponding to the first receiver and the multipath channel fading factor corresponding to the second set, respectively.

[0088] Step 212: for the multipath channel fading factor corresponding to each receiver, determine the Doppler shift corresponding to the multipath channel fading factor in the Gaussian Doppler function.

[0089] After obtaining the multipath channel fading factor corresponding to any receiver, the electronic device can determine the target Doppler parameter corresponding to the multipath channel fading factor in the Gaussian Doppler function, and further analyze the Doppler shift from the target Doppler parameter.

[0090] Here, the Gaussian Doppler function can be represented by the following formula (1):

[0091] (1)

[0092] Wherein, R(τ) is the multipath channel fading factor; π f D τ is the target Doppler parameter.

[0093] The τ in the target Doppler parameter can be obtained by multiplying the duration of a symbol in the protocol specified Wi-Fi signal and the symbol interval used to construct the multipath channel fading factor.

[0094] The electronic device can obtain the target Doppler parameter by substituting the multipath channel fading factor into the above formula (1), and then divide by π and τ to obtain the Doppler frequency shift f D .

[0095] Step 213: Convert the Doppler frequency shift corresponding to each receiver into the observed speed of the passive target relative to the receiver.

[0096] The electronic device can convert the Doppler frequency shift corresponding to the first receiver into the observed speed of the passive target relative to the first receiver, and convert the Doppler frequency shift corresponding to the second receiver into the observed speed of the passive target relative to the second receiver.

[0097] For example, the conversion method can be represented by the following formula (2):

[0098] (2)

[0099] Where v path is the observed speed; f D is the Doppler frequency shift; c is the speed of light; and f c is the known carrier frequency of the Wi-Fi signal.

[0100] Step 214: Combine the observed speed corresponding to the first receiver and the observed speed corresponding to the second receiver into the target moving speed.

[0101] Referring to Figure 6 , a schematic diagram for determining the target moving speed provided by an embodiment of the present application, as shown in Figure 6 , based on the direction and size of the observed speed corresponding to the first receiver (RX1 measurement speed) and the direction and size of the observed speed corresponding to the second receiver (RX2 measurement speed), the target moving speed can be combined.

[0102] Through the above measures, the electronic device can determine the target moving speed of the passive target in the environment coordinate system at each observation moment.

[0103] In an embodiment, referring to Figure 7 , a flowchart of a method for determining the multipath channel fading factor provided by an embodiment of the present application, as shown in Figure 7 , when step 211 is performed, the following steps 710 to 780 can be specifically performed.

[0104] Step 710: For the frequency domain channel estimation information corresponding to each receiver, convert the frequency domain channel estimation information into a time domain channel impulse response, and determine a power delay profile based on the time domain channel impulse response.

[0105] The electronic device can perform inverse fast Fourier transform (IFFT) on the frequency domain channel estimation information to obtain a time domain channel impulse response (CIR), and further determine a corresponding power-delay profile (PDP) based on the time domain channel impulse response.

[0106] At step 720, the power-delay profile is copied and spliced to obtain a specified power-delay profile; the specified power-delay profile includes powers of multiple sampling points.

[0107] Referring to Figure 8 A schematic diagram of the power-delay profile provided by an embodiment of the present application is shown in Figure 8 The power-delay profile includes powers of multiple sampling points, and each sampling point corresponds to a channel. Figure 8 There are 256 channels in the power-delay profile, including effective channels and noise channels other than the effective channels, and the effective channels include LOS channels and NLOS (Non Line of Sight) channels.

[0108] After copying the power-delay profile, the two power-delay profiles are spliced to obtain the specified power-delay profile. Referring to Figure 9 A schematic diagram of the specified power-delay profile spliced by the power-delay profile provided by an embodiment of the present application is shown in Figure 8 The specified power-delay profile includes multiple sampling points, and the indices of the sampling points are from -256 to 255. Figure 9

[0109] At step 730, the maximum power sum in the sliding search window is searched in the specified power-delay profile with a preset window length of the sliding window, and multiple window-in sampling points corresponding to the maximum power sum are used as sampling points corresponding to the effective channels.

[0110] The window length of the sliding window can be configured according to experience. In an embodiment, the window length can be the length of the cyclic prefix. Alternatively, the window length can be obtained by multiplying the length of the cyclic prefix by a coefficient.

[0111] The electronic device can place the left side of the sliding window at the middle part of the specified power-delay profile, and slide from right to left with a step of one. After each sliding, the power sum of multiple window-in sampling points is calculated. Through multiple calculations, the maximum power sum can be determined, and thus multiple window-in sampling points corresponding to the maximum power sum can be determined as sampling points corresponding to the effective channels. In this case, the indices of the window-in sampling points in the specified power-delay profile can be determined to indicate the window-in sampling points. Among them, for the Figure 9 ​The sampling point with a negative index can be selected according to an original positive index of the sampling point, or a positive index obtained by adding the negative index to a total number of sampling points in the power delay spectrum.

[0112] In step 740, the power of the first sampling point in the plurality of intra-window sampling points from left to right is set to zero, and the power sum of the plurality of intra-window sampling points is calculated.

[0113] After obtaining the plurality of intra-window sampling points, the first sampling point in the plurality of intra-window sampling points from left to right can be regarded as a sampling point corresponding to the LOS channel, the power of the sampling point is set to zero, and the power sum of the plurality of intra-window sampling points is calculated. At this time, the power sum is the power sum of the sampling points corresponding to the plurality of NLOS channels.

[0114] In step 750, based on the index of the sampling point corresponding to the effective channel, the time domain channel estimation value of the sampling point corresponding to the effective channel in the time domain channel impulse response is retained, and the time domain channel estimation values of other sampling points are set to zero, to obtain a denoised time domain channel impulse response.

[0115] In step 760, the first non-zero sampling point in the denoised time domain channel impulse response is set to zero, to obtain a cleaned time domain channel impulse response.

[0116] The electronic device can determine the sampling point corresponding to the effective channel in the time domain channel impulse response based on the index of the sampling point corresponding to the effective channel, and then set the time domain channel estimation values of other sampling points except the sampling point corresponding to the effective channel to zero, to obtain a denoised time domain channel impulse response. The denoised time domain channel impulse response removes the time domain channel estimation values of the noise channels.

[0117] The first non-zero sampling point in the denoised time domain channel impulse response is set to zero, and the sampling point is the sampling point corresponding to the LOS channel. At this time, a cleaned time domain channel impulse response is obtained. The cleaned time domain channel impulse response includes the time domain channel estimation values of the sampling points corresponding to the plurality of NLOS channels.

[0118] In step 770, the cleaned time domain channel impulse responses corresponding to two symbols in the same data packet are conjugate multiplied to obtain a correlation power value.

[0119] For each data packet transmitted by the Wi-Fi signal, the electronic device can select the frequency domain channel estimation information of two symbols in the data packet for processing, to obtain the cleaned time domain channel impulse responses corresponding to the two symbols. The symbol interval between the two symbols can be preconfigured.

[0120] After obtaining the cleaned time domain channel impulse responses corresponding to the two symbols, the two cleaned time domain channel impulse responses can be conjugate multiplied to obtain a correlation power value.

[0121] Step 780: divide the correlation power value by the power sum to obtain a multipath channel fading factor.

[0122] The electronic device can divide the correlation power value by the power sum to obtain a multipath channel fading factor. In the case that the passive target is static, the correlation power value is the same as the power sum, and the multipath channel fading factor is one; in the case that the passive target is moving, the correlation power value is different from the power sum.

[0123] Through the above measures, the corresponding multipath channel fading factor at each observation time can be calculated for each receiver.

[0124] In an embodiment, before step 230 is performed, the electronic device can determine the power sum of the NLOS channel at each observation time. Here, the power sum at each observation time can be calculated in the manner of the aforementioned step 740; since two power sums can be calculated at the same observation time through the first receiver and the second receiver, one of the two larger values can be selected, or the power sum of one of the receivers can be selected all the time.

[0125] The electronic device can take the power sum at the observation time corresponding to the initial position as a reference to normalize the power sum at each observation time to obtain the PDP observation ratio corresponding to each coordinate position in the candidate motion trajectory. In other words, the power sum at each observation time is divided by the power sum at the observation time corresponding to the initial position to obtain the normalized power sum as the PDP observation ratio.

[0126] In an embodiment, before step 250 is performed, the electronic device can filter out the candidate motion trajectory that exceeds the specified boundary range in the environmental coordinate system from the plurality of candidate motion trajectories. Here, the specified boundary range can be the boundary range in the environmental coordinate system that can apply the scheme of the present application; when the passive target leaves the specified boundary range, the passive target cannot be accurately positioned through the scheme of the present application. Illustratively, the third position information of the transmitter is (0, 0), the first position information of the first receiver is (8, 0), and the second position information of the second receiver is (0, 8), and then the specified boundary range can be a rectangular region defined by the four vertices (0, 0), (8, 0), (0, 8), and (8, 8); when the passive target moves within the rectangular region, the passive target can be accurately tracked, and when the passive target leaves the rectangular region, the passive target cannot be accurately tracked.

[0127] In the process of tracking and positioning the passive target at each observation time, if there is a coordinate position in any candidate motion trajectory that exceeds the specified boundary range, it can be considered that the candidate motion trajectory exceeds the specified boundary range, at which point the candidate motion trajectory can be filtered out and no longer be continuously updated.

[0128] By the above measures, for the candidate motion trajectory exceeding the specified boundary range, it can be considered as untrusted, and the invalid tracking workload is reduced.

[0129] In an embodiment, in the process of performing step 250, when the number of observation time reaches a preset number threshold, if multiple candidate motion trajectories are screened out, the electronic device can select any candidate motion trajectory from the multiple candidate motion trajectories as the tracking result of the passive target. Here, the number threshold can be configured as needed, and exemplarily, the number threshold can be any value such as 10, 15, 20, etc.

[0130] In the tracking process, the number of candidate motion trajectories screened out at each observation time may become less and less over time, and at each observation time, one can be randomly selected from the multiple candidate motion trajectories currently screened out as the tracking result of the passive target.

[0131] In an embodiment, in the process of performing step 250, when the number of observation time reaches a preset number threshold, if multiple candidate motion trajectories are screened out, the electronic device can merge the multiple candidate motion trajectories screened out, so as to take the merged motion trajectory as the tracking result of the passive target. Here, the number threshold can be configured as needed, and exemplarily, the number threshold can be any value such as 10, 15, 20, etc.

[0132] In the merging, the coordinate positions of each observation time in the multiple candidate motion trajectories can be averaged to obtain the actual coordinate position of the observation time, and thus the actual coordinate positions of multiple observation times are used to construct the merged motion trajectory as the tracking result of the passive target.

[0133] Figure 10 is a block diagram of a tracking device based on a Fresnel region according to an embodiment of the present application, as shown in the figure, the device can include: Figure 10

[0134] The first determination module 1010 is configured to determine the target moving speed of the passive target relative to the Wi-Fi transceiver system based on the frequency domain channel estimation information corresponding to each receiver;

[0135] The construction module 1020 is configured to take multiple grids in the environment coordinate system as initial positions, and construct candidate motion trajectories corresponding to each initial position based on the target moving speed of multiple observation times; each candidate motion trajectory includes multiple coordinate positions.

[0136] The second determination module 1030 is configured to determine, for each candidate motion trajectory, the energy hotspot trajectory corresponding to the candidate motion trajectory based on the PDP observation ratio of the observation time corresponding to each coordinate position in the candidate motion trajectory.​

[0137] The generating module 1040 is configured to generate a signal intensity hotspot map corresponding to the environmental coordinate system according to the first position information of the first receiver, the second position information of the second receiver, the power of the transmitter, and the third position information of the transmitter based on the principle of Fresnel zone.

[0138] The tracking module 1050 is configured to determine, for each candidate motion trajectory, whether the energy hotspot trajectory corresponding to the candidate motion trajectory matches the signal intensity hotspot map, and take the candidate motion trajectory corresponding to the energy hotspot trajectory that matches the signal intensity hotspot map as the tracking result of the passive target.

[0139] The functions and effects of the modules in the above device are specifically described in the implementation process of the corresponding steps in the above tracking method based on Fresnel zone, and will not be described here.

[0140] In several embodiments provided in the present application, the disclosed device and method can also be implemented in other ways. The device embodiments described above are only schematic, for example, the flowcharts and block diagrams in the drawings show the possible implementation architectures, functions and operations of the device, method and computer program product according to the embodiments of the present application. In this regard, each block in the flowcharts or block diagrams can represent a module, a program segment or a part of code, which contains one or more executable instructions for implementing the specified logical functions. In some alternative implementation manners, the functions noted in the blocks can also occur in different orders from those noted in the drawings. For example, two consecutive blocks can actually be executed substantially in parallel, and sometimes they can be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and the combination of blocks in the block diagrams and / or flowcharts, can be implemented by a dedicated hardware-based system for implementing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0141] In addition, each functional module in the embodiments of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0142] If the functions are implemented in the form of software function modules and sold or used as independent products, the functions can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the embodiments of the method of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

Claims

1. A Fresnel zone based tracking method applied to a Wi-Fi transceiving system, the Wi-Fi transceiving system comprising a transmitter, a first receiver and a second receiver, characterized in that, The method comprises: determining the target moving speed of the passive target relative to the Wi-Fi transceiving system based on the frequency domain channel estimation information corresponding to each receiver, comprising: cleaning the frequency domain channel estimation information corresponding to each receiver, and determining the multipath channel fading factor corresponding to the cleaned frequency domain channel estimation information; determining the Doppler shift corresponding to the multipath channel fading factor in a Gaussian Doppler function for the multipath channel fading factor corresponding to each receiver; converting the Doppler shift corresponding to each receiver into the observed speed of the passive target relative to the receiver; and combining the observed speed corresponding to the first receiver and the observed speed corresponding to the second receiver into the target moving speed; wherein the cleaning of the frequency domain channel estimation information corresponding to each receiver and the determination of the multipath channel fading factor corresponding to the cleaned frequency domain channel estimation information comprise: converting the frequency domain channel estimation information corresponding to each receiver into a time domain channel impulse response, and determining a power delay profile based on the time domain channel impulse response; copying and splicing the power delay profile to obtain a specified power delay profile; wherein the specified power delay profile comprises the power of a plurality of sampling points; slidingly searching the maximum power sum in a preset window length in the specified power delay profile, and taking the plurality of window-in sampling points corresponding to the maximum power sum as the sampling points corresponding to the effective channel; setting the power of the first window-in sampling point from left to right in the plurality of window-in sampling points to zero, and calculating the power sum of the plurality of window-in sampling points; based on the index of the sampling points corresponding to the effective channel, retaining the time domain channel estimation value of the sampling points corresponding to the effective channel in the time domain channel impulse response, and setting the time domain channel estimation values of other sampling points to zero to obtain a denoised time domain channel impulse response; setting the first non-zero sampling point in the denoised time domain channel impulse response to zero to obtain a cleaned time domain channel impulse response; conjugate multiplying the cleaned time domain channel impulse responses corresponding to two symbols in the same data packet to obtain a correlation power value; and dividing the correlation power value by the power sum to obtain a multipath channel fading factor; taking a plurality of grids in an environmental coordinate system as initial positions, and constructing a candidate motion trajectory corresponding to each initial position based on the target moving speed at a plurality of observation times; wherein each candidate motion trajectory comprises a plurality of coordinate positions; determining an energy hotspot trajectory diagram corresponding to each candidate motion trajectory based on the PDP observation ratio of each coordinate position in the candidate motion trajectory and the observation time corresponding to the coordinate position; generating a signal strength hotspot diagram corresponding to the environmental coordinate system based on the first position information of the first receiver, the second position information of the second receiver, the power of the transmitter, and the third position information of the transmitter according to the principle of Fresnel zone. For each candidate motion trajectory, it is judged whether the energy hot spot trajectory corresponding to the candidate motion trajectory matches the signal strength hot spot map, and the candidate motion trajectory corresponding to the energy hot spot trajectory matching the signal strength hot spot map is taken as the tracking result of the passive target.

2. The method of claim 1, wherein, Before the method further comprises the following steps: Determine the power sum of the NLOS channel at each observation time; Take the power sum at the observation time corresponding to the initial position as a reference to normalize the power sum at each observation time to obtain the PDP observation ratio at the observation time corresponding to each coordinate position in the candidate motion trajectory.

3. The method of claim 1, wherein, Before the method further comprises the following steps: Based on the specified boundary range in the environment coordinate system, filter out the candidate motion trajectories in the plurality of candidate motion trajectories that exceed the specified boundary range.

4. The method of claim 1, wherein, The candidate motion trajectory corresponding to the energy hot spot trajectory matching the signal strength hot spot map is taken as the tracking result of the passive target, comprising: When the number of observation times reaches a preset number threshold, if a plurality of candidate motion trajectories are screened out, any candidate motion trajectory is selected from the plurality of candidate motion trajectories as the tracking result of the passive target.

5. The method of claim 1, wherein, The candidate motion trajectory corresponding to the energy hot spot trajectory matching the signal strength hot spot map is taken as the tracking result of the passive target, comprising: When the number of observation times reaches a preset number threshold, if a plurality of candidate motion trajectories are screened out, the plurality of candidate motion trajectories are merged, and the merged motion trajectory is taken as the tracking result of the passive target.

6. A Fresnel zone based tracking device applied to a Wi-Fi transceiving system, the Wi-Fi transceiving system comprising a transmitter, a first receiver and a second receiver, characterized in that, Comprise: The first determination module is configured to determine the target moving speed of the passive target relative to the Wi-Fi transceiver system based on the frequency domain channel estimation information corresponding to each receiver, including: cleaning the frequency domain channel estimation information corresponding to each receiver, and determining the multipath channel fading factor corresponding to the cleaned frequency domain channel estimation information; for the multipath channel fading factor corresponding to each receiver, determining the Doppler frequency shift corresponding to the multipath channel fading factor in the Gaussian Doppler function; converting the Doppler frequency shift corresponding to each receiver into the observation speed of the passive target relative to the receiver; and merging the observation speed corresponding to the first receiver and the observation speed corresponding to the second receiver into the target moving speed. The cleaning of the frequency domain channel estimation information corresponding to each receiver and the determination of the multipath channel fading factor corresponding to the cleaned frequency domain channel estimation information comprises: for the frequency domain channel estimation information corresponding to each receiver, converting the frequency domain channel estimation information into a time domain channel impulse response, and determining a power delay profile based on the time domain channel impulse response; copying and splicing the power delay profile to obtain a specified power delay profile; wherein the specified power delay profile comprises the power of a plurality of sampling points; sliding a window of a preset window length in the specified power delay profile, slidingly searching for the maximum power sum in the window, and taking the plurality of window-in sampling points corresponding to the maximum power sum as the sampling points corresponding to the effective channel; setting the power of the first window-in sampling point from left to right in the plurality of window-in sampling points to zero, and calculating the power sum of the plurality of window-in sampling points; based on the indexes of the sampling points corresponding to the effective channel, retaining the time domain channel estimation values of the sampling points corresponding to the effective channel in the time domain channel impulse response, and setting the time domain channel estimation values of the other sampling points to zero to obtain a denoised time domain channel impulse response; setting the first non-zero sampling point in the denoised time domain channel impulse response to zero to obtain a cleaned time domain channel impulse response; conjugate multiplying the cleaned time domain channel impulse responses corresponding to two symbols in the same data packet to obtain a correlation power value; dividing the correlation power value by the power sum to obtain a multipath channel fading factor; The constructing module is configured to construct a candidate motion trajectory corresponding to each initial position based on target moving speeds at a plurality of observation times, with a plurality of grids in an environmental coordinate system as the initial positions; each candidate motion trajectory includes a plurality of coordinate positions; The second determining module is configured to determine, for each candidate motion trajectory and a PDP observation ratio at observation times corresponding to the coordinate positions in the candidate motion trajectory, an energy hot spot trajectory diagram corresponding to the candidate motion trajectory; The generating module is configured to generate a signal strength hot spot diagram corresponding to the environmental coordinate system based on first position information of the first receiver, second position information of the second receiver, power of the transmitter, and third position information of the transmitter according to a Fresnel region principle. The tracking module is configured to determine, for each candidate motion trajectory, whether the energy hot spot trajectory diagram corresponding to the candidate motion trajectory matches the signal strength hot spot diagram, and take a candidate motion trajectory corresponding to an energy hot spot trajectory diagram that matches the signal strength hot spot diagram as a tracking result of the passive target.

7. An electronic device, comprising: The electronic device comprises: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to execute the tracking method based on the Fresnel region according to any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The storage medium stores a computer program that can be executed by the processor to complete the tracking method based on the Fresnel region according to any one of claims 1-5.

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