An integrated sensing and backscatter communication method and device based on inverse scattering

Abstract

The present invention discloses an integrated sensing and backscatter communication method and apparatus based on inverse scattering, relating to the field of wireless communication technologies. The method includes: determining a tag antenna mode pilot voltage component and a clutter tag structure combined pilot voltage component according to an open-circuit pilot received voltage and a short-circuit pilot received voltage generated by a receiving antenna based on a pilot signal; respectively determining a tag antenna mode reflection coefficient and a clutter tag structure combined reflection coefficient based on the tag antenna mode pilot voltage component and the clutter tag structure combined pilot voltage component by using a compressive sensing algorithm; transmitting a data signal to the receiving antenna by the tag using binary phase shift keying and collecting a data received voltage; and completing signal demodulation by using the data received voltage, the tag antenna mode reflection coefficient, and the combined reflection coefficient to obtain a bit mapping symbol of the data signal. By combining inverse scattering with modulating the tag impedance to implement backscatter communication, the performance of backscatter communication is improved.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and in particular, to an integrated sensing and backscatter communication method and device based on inverse scattering. Background Art

[0002] In the process of the rapid development of the Internet of Things, backscatter communication has received extensive attention as a low-cost and high-efficiency data transmission method. With the rise of the concept of Integrated Sensing and Communication (ISAC), it has become possible to share limited spectrum and expensive hardware resources between communication and sensing systems. Such integration can not only save a large amount of costs but also promote powerful communication and high-precision sensing capabilities. In this context, the academic and industrial communities have begun to study integrating positioning technologies into backscatter communication systems to achieve precise sensing.

[0003] In the prior art, positioning of passive tag antennas in backscatter systems is usually performed based on methods such as signal strength and phase difference ranging. However, it is prone to problems of multipath effects caused by clutter scatterers, which affect the positioning accuracy and result in low backscatter communication performance. Summary of the Invention

[0004] The present invention provides an integrated sensing and backscatter communication method and device based on inverse scattering, which solves the technical problem in the prior art that when positioning passive tag antennas in backscatter systems, it is prone to problems of multipath effects caused by clutter scatterers, which affect the positioning accuracy and result in low backscatter communication performance.

[0005] An integrated sensing and backscatter communication method based on inverse scattering provided in the first aspect of the present invention includes:

[0006] After transmitting a pilot signal to a tag through a transmitting antenna, modulating the tag to be in an open state to generate an open-circuit pilot signal of the pilot signal and in a short-circuit state to generate a short-circuit pilot signal of the pilot signal, and backscattering the open-circuit pilot signal and the short-circuit pilot signal to a receiving antenna;

[0007] Based on the open-circuit pilot received voltage generated by the receiving antenna based on the open-circuit pilot signal and the short-circuit pilot received voltage generated by the short-circuit pilot signal, determining a tag antenna mode pilot voltage component and a clutter tag structure combination pilot voltage component;

[0008] Using a compressive sensing algorithm to respectively construct an underdetermined linear equation system based on the tag antenna mode pilot voltage component and the clutter tag structure combination pilot voltage component and perform optimization and solution, and correspondingly determining a tag antenna mode reflection coefficient and a clutter tag structure combination reflection coefficient;

[0009] When the transmitting antenna activates the tag, the tag transmits a data signal to the receiving antenna by using binary phase shift keying, and the data reception voltage of the receiving antenna is collected.

[0010] The tag antenna mode data voltage component and the clutter tag structure combined data voltage component of the data signal are respectively determined by using the reflection coefficient of the tag antenna mode and the combined reflection coefficient of the clutter tag structure.

[0011] The data signal is demodulated by combining the data reception voltage, the clutter tag structure combined data voltage component and the tag antenna mode data voltage component to obtain the bit mapping symbol of the data signal.

[0012] Optionally, determining the tag antenna mode pilot voltage component and the clutter tag structure combined pilot voltage component according to the open-circuit pilot reception voltage generated by the receiving antenna based on the open-circuit pilot signal and the short-circuit pilot reception voltage generated by the short-circuit pilot signal includes:

[0013] Collect the open-circuit pilot reception voltage generated by the receiving antenna based on the open-circuit pilot signal and the short-circuit pilot reception voltage generated by the short-circuit pilot signal.

[0014] Take half of the difference between the open-circuit pilot reception voltage and the short-circuit pilot reception voltage to obtain the tag antenna mode pilot voltage component.

[0015] Perform an averaging operation on the open-circuit pilot reception voltage and the short-circuit pilot reception voltage to obtain the clutter tag structure combined pilot voltage component.

[0016] Optionally, respectively constructing an underdetermined linear equation set based on the tag antenna mode voltage component and the clutter tag structure combined voltage component by using a compressive sensing algorithm and performing optimization and solution, and correspondingly determining the reflection coefficient of the tag antenna mode and the combined reflection coefficient of the clutter tag structure includes:

[0017] Construct a first underdetermined linear equation set about the combined reflection coefficient of the clutter tag structure based on the clutter tag structure combined voltage component by using a compressive sensing algorithm.

[0018] Use a two-step iterative shrinkage threshold algorithm to perform optimization and solution on the first underdetermined linear equation set to determine the combined reflection coefficient of the clutter tag structure.

[0019] Construct a second underdetermined linear equation set about the reflection coefficient of the tag antenna mode based on the tag antenna mode voltage component by using a compressive sensing algorithm.

[0020] The second underdetermined linear equation set is optimized and solved by using a two-step iterative shrinkage threshold algorithm to determine the reflection coefficient of the tag antenna pattern.

[0021] Optionally, demodulating the signal by combining the data reception voltage, the clutter tag structure combined data voltage component, and the tag antenna pattern data voltage component to obtain the bit mapping symbol of the data signal includes:

[0022] Performing a subtraction operation on the data reception voltage and the clutter tag structure combined data voltage component to obtain the reception signal of the reception antenna;

[0023] Inputting the reception signal and the tag antenna pattern data voltage component into a preset reverse communication model and demodulating through maximum ratio combining to obtain the bit mapping symbol of the data signal.

[0024] Optionally, the reverse communication model is specifically:

[0025] ;

[0026] In the formula, is the reception signal of the th bit mapping symbol, is the tag antenna pattern voltage component vector, is the th bit mapping symbol, is the noise of the th bit mapping symbol.

[0027] Optionally, the determination process of the tag antenna pattern data voltage component is specifically:

[0028] ;

[0029] The determination process of the clutter tag structure combined data voltage component is specifically:

[0030] ;

[0031] In the formula, is the th transmitting antenna, is the th receiving antenna, is the tag antenna pattern voltage component, is an imaginary number, is the angular frequency, is the vacuum permeability, is the normalization factor, is the region of interest where the tag and clutter scatterers are located, is the The field radiated by a receiving antenna when operating in a transmit mode with unit excitation, is the incident field generated by the th transmitting antenna at position . is the reflection coefficient of the tag antenna mode, is the area of each spatial pixel in the region of interest, is the combined voltage component of the clutter tag structure, is the combined reflection coefficient of the clutter tag structure.

[0032] An integrated sensing and backscatter communication device based on inverse scattering provided by the second aspect of the present invention includes:

[0033] A pilot modulation module, configured to modulate the tag to be in an open state to generate an open-circuit pilot signal of the pilot signal and in a short-circuit state to generate a short-circuit pilot signal of the pilot signal after transmitting a pilot signal to the tag through a transmitting antenna, and backscatter the open-circuit pilot signal and the short-circuit pilot signal to a receiving antenna;

[0034] A pilot voltage determination module, configured to determine a tag antenna mode pilot voltage component and a combined pilot voltage component of the clutter tag structure according to an open-circuit pilot received voltage generated by the receiving antenna based on the open-circuit pilot signal and a short-circuit pilot received voltage generated by the short-circuit pilot signal;

[0035] A reflection coefficient determination module, configured to respectively construct an underdetermined linear equation set based on the tag antenna mode pilot voltage component and the combined pilot voltage component of the clutter tag structure by using a compressive sensing algorithm and perform optimization and solution, and correspondingly determine a tag antenna mode reflection coefficient and a combined reflection coefficient of the clutter tag structure;

[0036] A signal transmission and acquisition module, configured to, when the transmitting antenna activates the tag, transmit a data signal to the receiving antenna through the tag by using binary phase shift keying and acquire a data received voltage of the receiving antenna;

[0037] A signal voltage calculation module, configured to respectively use the tag antenna mode reflection coefficient and the combined reflection coefficient of the clutter tag structure to correspondingly determine a tag antenna mode data voltage component and a combined data voltage component of the clutter tag structure of the data signal;

[0038] A signal demodulation module, configured to perform signal demodulation by combining the data received voltage, the combined data voltage component of the clutter tag structure and the tag antenna mode data voltage component to obtain a bit mapping symbol of the data signal.

[0039] A computer device provided in the third aspect of the present invention includes a memory and a processor. A computer program is stored in the memory. When the computer program is executed by the processor, the processor executes the steps of the integrated sensing and backscatter communication method based on inverse scattering as described in any one of the above.

[0040] A computer-readable storage medium provided in the fourth aspect of the present invention has a computer program stored thereon. When the computer program is executed, it implements the integrated sensing and backscatter communication method based on inverse scattering as described in any one of the above.

[0041] A computer program product provided in the fifth aspect of the present invention includes a computer program / instructions. When the computer program / instructions are executed by a processor, they implement the integrated sensing and backscatter communication method based on inverse scattering as described in any one of the above.

[0042] From the above technical solutions, it can be seen that the present invention has the following advantages:

[0043] The above solution of the present invention provides an integrated sensing and backscatter communication method based on inverse scattering, including: after transmitting a pilot signal to a tag through a transmitting antenna, modulating the tag to be in an open state and a short state respectively and corresponding backscattering the pilot signal to a receiving antenna; determining the pilot voltage component of the tag antenna mode and the combined pilot voltage component of the clutter scatterer and the tag structure mode based on the pilot received voltage generated by the receiving antenna for each pilot signal; using the compressive sensing algorithm to construct an underdetermined linear equation system based on the pilot voltage component of the tag antenna mode and the combined pilot voltage component respectively and performing optimization and solution, corresponding to determining the reflection coefficient of the tag antenna mode and the combined reflection coefficient; when the transmitting antenna activates the tag, transmitting a data signal to the receiving antenna through the tag using binary phase shift keying, and correspondingly collecting the data received voltage of the receiving antenna; respectively using the reflection coefficient of the tag antenna mode and the combined reflection coefficient to determine the data voltage component of the tag antenna mode associated with the data signal and the combined data voltage component of the clutter tag structure; jointly demodulating the signal with the data received voltage, the combined data voltage component of the clutter tag structure and the data voltage component of the tag antenna mode to obtain the bit mapping symbol of the data signal. Based on the above solution, by modulating the tag in the open and short states, the pilot voltage component of the tag antenna mode and the combined pilot voltage component of the clutter tag structure are respectively extracted, applying the inverse scattering and compressive sensing algorithms, sensing the tag and the clutter scatterer based on the combined pilot voltage component of the clutter tag structure, and using the pilot voltage component of the tag antenna mode for tag identification, combining the imaging method based on inverse scattering with modulating the impedance of the tag to achieve backscatter communication, can realize the simultaneous localization, identification and backscatter communication of the tag in a chaotic environment, and improve the performance of backscatter communication. Description of the Drawings

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0045] Figure 1 The flowchart of the steps of an integrated sensing and backscatter communication method based on inverse scattering provided by an embodiment of the present invention;

[0046] Figure 2 The structural schematic diagram of the integrated sensing and backscatter communication system provided by an embodiment of the present invention;

[0047] Figure 3 The schematic diagram of the sensing and recognition results of three tags and a closed clutter scatterer provided by an embodiment of the present invention;

[0048] Figure 4 The scatter response results at the receiving antenna in the scenario of a single copper dipole antenna and a single copper clutter scatterer for the integrated sensing and backscatter communication system provided by an embodiment of the present invention;

[0049] Figure 5 The BER performance of the bit mapping symbols at different SNRs in the Monte Carlo simulation for the integrated sensing and backscatter communication system provided by an embodiment of the present invention;

[0050] Figure 6 The structural block diagram of an integrated sensing and backscatter communication device based on inverse scattering provided by an embodiment of the present invention. Detailed implementation manners

[0051] The embodiments of the present invention provide an integrated sensing and backscatter communication method and device based on inverse scattering, which are used to solve the technical problem that in the prior art, when positioning the passive tag antenna in a backscatter system, the multipath effect caused by clutter scatterers is likely to occur, affecting the positioning accuracy and resulting in poor backscatter communication performance.

[0052] To make the objectives, features, and advantages of the present invention more obvious and understandable, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0053] Please refer to Figure 1 ,Figure 1 Flowchart showing the steps of an integrated sensing and backscatter communication method based on inverse scattering according to an embodiment of the present invention.

[0054] An integrated sensing and backscatter communication method based on inverse scattering provided by the present invention includes:

[0055] Step 101: After transmitting a pilot signal to a tag through a transmitting antenna, modulate the tag to be in an open state to generate an open-circuit pilot signal of the pilot signal and in a short-circuit state to generate a short-circuit pilot signal of the pilot signal, and backscatter the open-circuit pilot signal and the short-circuit pilot signal to a receiving antenna.

[0056] It should be noted that this embodiment is applied to an integrated sensing and backscatter communication system. As Figure 2 shown, the system is equipped with a transmitting antenna array composed of receiving antennas (Receive Array) and a receiving antenna array composed of transmitting antennas (Transmit Array). The transmitting antenna array and the receiving antenna array are both placed outside the domain of interest (DOI). In specific implementation, , when the th transmitting antenna transmits, measurement values can be correspondingly collected from the receiving antennas, which allows a total of

[0057] measurements; To simplify the description, the considered domain of interest DOI is represented as a two-dimensional (2D) plane section. The DOI is limited to the region, denoted as D. The DOI is further divided into pixels, where , respectively represent the number of spatial pixels in the x - y plane. is the unit length in the x-axis direction, is the unit length in the y-axis direction. The area of each spatial pixel is ; There are a total of spatial pixels in the DOI, where ; In this embodiment, the DOI contains clutter scatterers with a constant reflection coefficient and tags whose backscatter communication reflection coefficient can be modulated. For the number of transmitting antennas, receiving antennas, clutter scatterers, and tags, each structure can be single or multiple;

[0058] Assuming that the DOI can be approximated by a uniform grid of point scatterers with reflectivity values, we can write the entire field as:

[0059] (1)

[0060] where is the total electric field generated by the th transmitting antenna at position , is the incident field generated by the th transmitting antenna at position , is the scattered field generated by the th transmitting antenna at position ;

[0061] The scattered field at any point in the DOI can be further expressed as:

[0062] (2)

[0063] where is the reflection coefficient of the clutter scatterers and tags at position ;

[0064] And a general tag consists of an antenna and a load. Modulating the tag scattered field is achieved by controlling the mismatch between the antenna impedance and the load impedance. As the reflection coefficient is defined as:

[0065] (3)

[0066] where is the tag reflection coefficient, is the antenna impedance, is the load impedance, is the complex conjugate operation; when , ; when the th transmitting antenna transmits, the scattered field of the tag with the load impedance can be decomposed as:

[0067] (4)

[0068] where is the scattered field of the tag structure mode, is the scattered field of the tag antenna mode, is the scattered current with conjugate matching induced by the incident field of the transmitting antenna at the tag antenna, The radiation field of the tag antenna for unit excitation; it can be understood that the tag scattering field includes the scattering fields of two parts, the structural mode and the antenna mode. Among them, the scattering field of the tag structural mode is not affected by the load impedance and is determined by physical properties such as shape, size, position, and composition. The scattering field of the tag antenna mode depends on the load conditions and can be modulated to facilitate data transmission in backscatter communication, which also makes it possible to identify the tag from clutter scatterers; represent the scattering field of the clutter scatterer as Then, the scattering field in Equation (2) can be rewritten as:

[0069] (5)

[0070] In addition, the scattering field of the clutter scatterer and the scattering field of the tag structural mode can be combined into a constant clutter-tag structure combined scattering field which is independent of the load impedance of the tag, and the expression is as follows:

[0071] (6)

[0072] Combining Equations (2), (5), and (6), can be decomposed into:

[0073] (7)

[0074] In the formula, is the clutter-tag structure combined reflection coefficient, is the tag antenna mode reflection coefficient; furthermore:

[0075] (8)

[0076] (9)

[0077] Therefore, in this embodiment, the clutter-tag structure combined reflection coefficient can be used to sense the positions of the clutter scatterer and the tag, and at the same time, the tag antenna mode reflection coefficient is used to identify the tag from the clutter scatterer;

[0078] By changing the load impedance , the tag can present different reflection coefficients through the antenna mode. In this embodiment, the open-circuit and short-circuit load impedances, that is, binary phase shift keying (BPSK), are taken as examples to verify the above concept. For the load impedance in the open-circuit state, there is , and for the load impedance in the open-circuit state, there is , then based on Equation (5), the scattered field can be respectively expressed as:

[0079] (10)

[0080] (11)

[0081] By performing conversions based on Equation (10) and Equation (11), the clutter label structure combined scattered field and the scattered field of the label antenna pattern can be obtained as follows:

[0082] (12)

[0083] (13)

[0084] By verifying Equation (12)-(13), it is shown that we can extract the clutter label structure combined scattered field and the scattered field of the label antenna pattern ;

[0085] In practical applications, it is not feasible to directly measure the scattered fields in Equation (2) and Equation (5). Therefore, usually a receiving antenna is used to sense the scattered field and convert it into a measurable received voltage. The scattered field at position can be expressed as:

[0086] (14)

[0087] wherein, is at the position, is an imaginary number, is the angular frequency, is the vacuum permeability, is the Green's function, and the Green's function is written as the Hankel function in a two-dimensional scenario ; replacing the Green's function in Equation (14) with the electric field radiated by the receiving antenna operating in the unit excitation emission mode, so that the measurable received voltage can be related to the scattered field:

[0088] (15)

[0089] wherein, is the received voltage generated by the scattered field generated by the th receiving antenna due to the th transmitting antenna, is the field radiated by the ​​is the normalization factor;

[0090] Since there are two unknowns in Equation (15) and , it is impossible to infer only from the received voltage measured at the receiving antenna. At this time, the linear Born approximation is used to solve this problem, and the total electric field is approximated as the incident field . Thus, the inverse scattering problem Equation (15) can be simplified to:

[0091] (16)

[0092] Based on Equation (7), the received voltage can be decomposed into:

[0093] (17)

[0094] where is the combined voltage component of the clutter tag structure, is the voltage component of the tag antenna pattern; Combining Equation (16) gives:

[0095] (18)

[0096] (19)

[0097] Therefore, by given and can be estimated respectively and , and then used to sense the positions of the clutter scatterer and the tag, and identify the tag from the clutter scatterer.

[0098] In specific implementation, first, a pilot signal is transmitted to the tag through the transmitting antenna to activate the tag. The pilot signal is usually a known reference signal, which is commonly used in processes such as channel estimation, synchronization, and frequency correction. At this time, the modulation tag is respectively in the open state and the short state. The open-circuit pilot signal is generated by modulation in the open state, and the short-circuit pilot signal is generated by modulation in the short state, and both are backscattered to the receiving antenna to generate corresponding received voltages at the receiving antenna.

[0099] Step 102, determine the tag antenna pattern pilot voltage component and the clutter tag structure combined pilot voltage component according to the open-circuit pilot received voltage generated by the receiving antenna based on the open-circuit pilot signal and the short-circuit pilot received voltage generated by the short-circuit pilot signal.

[0100] Step 102 includes the following sub-steps:

[0101] S11. Collect the receiving antenna based on the open-circuit pilot signal The generated open - circuit pilot received voltage and based on the short - circuit pilot signal The generated short - circuit pilot received voltage;

[0102] S12. Take half of the difference between the open - circuit pilot received voltage and the short - circuit pilot received voltage to obtain the tag antenna pattern pilot voltage component;

[0103] S13. Perform an average operation on the open - circuit pilot received voltage and the short - circuit pilot received voltage to obtain the clutter tag structure combined pilot voltage component.

[0104] It should be noted that based on Equation (17), the received voltages corresponding to the open - circuit pilot signal and the short - circuit pilot signal are:

[0105] (20)

[0106] (21)

[0107] Based on the conversion of Equation (20) and Equation (21), we can obtain:

[0108] (22)

[0109] (23)

[0110] In the formula, is the open - circuit pilot received voltage, is the short - circuit pilot received voltage; since there are transmitting antennas and receiving antennas, and in 、 , and can be combined into a vector, so it can be denoted as the clutter tag structure combined voltage component vector and the tag antenna pattern voltage component vector , where, , .

[0111] Step 103. Use the compressive sensing algorithm to construct an under - determined linear equation set based on the tag antenna pattern pilot voltage component and the clutter tag structure combined pilot voltage component respectively, and perform optimization and solution to determine the tag antenna pattern reflection coefficient and the clutter tag structure combined reflection coefficient correspondingly.

[0112] Step 103 includes the following sub - steps:

[0113] S21. Use the compressive sensing algorithm to construct a first under - determined linear equation set about the clutter tag structure combined reflection coefficient based on the clutter tag structure combined voltage component.

[0114] S22. Use the two-step iterative shrinkage threshold algorithm to optimize and solve the first underdetermined linear equation system to determine the clutter label structure combination reflection coefficient.

[0115] It should be noted that first, consider using the clutter label structure combination voltage component to sense the positions of the clutter scatterers and labels. From Equation (18), we can obtain:

[0116] (24)

[0117] where can be split into different directions, that is , is the measurement matrix arranged according to , where , is the number of columns or rows of the matrix. The transmitting antenna incident vector represents the incident field generated by the th transmitting antenna within the DOI, and the receiving antenna incident vector represents the incident field generated by the th receiving antenna within the DOI;

[0118] Retrieve the clutter label structure combination reflection coefficient from the measurement value obtained from Equation (24). The direct method is to find the inverse measurement matrix such that . However, since the number of independent observations is usually less than the number of unknowns N, the measurement matrix H is usually non-invertible. For sparse objects or scatterers, the compressed sensing algorithm (compressed sensing methods, CS algorithm) can be used to solve the underdetermined problem to achieve image reconstruction. Specifically, the problem can be formulated as the first underdetermined linear equation system regarding the clutter label structure combination reflection coefficient in which the clutter scatterers and the label structure patterns are combined together:

[0119] (25)

[0120] In the formula, is the L1 norm; use the two-step iterative shrinkage thresholding algorithm (two-step iterative shrinkage thresholding algorithm, TwIST) to optimize and solve the first underdetermined linear equation system, and iteratively update the estimated reflection coefficient by applying the shrinkage and threshold operations, so as to recover the sparse clutter label structure combination reflection coefficient . Since represents the reflection coefficient of the clutter scatterers and the label structure patterns, we can thus obtain from the recovered The positions of the clutter scatterers and tags are sensed, but it is not sufficient to identify the tags from the clutter scatterers. Therefore, in order to identify the tags, restoration is still required. 。

[0121] S23. Based on the voltage components of the tag antenna pattern, a second underdetermined linear equation system regarding the reflection coefficients of the tag antenna pattern is constructed by using the compressive sensing algorithm.

[0122] S24. The two-step iterative shrinkage threshold algorithm is used to optimize and solve the second underdetermined linear equation system to determine the reflection coefficients of the tag antenna pattern.

[0123] It should be noted that considering using the voltage components of the tag antenna pattern to identify the tags from the clutter scatterers, similar to the restoration process, as shown in Equations (26) and (27), the compressive sensing algorithm and the two-step iterative shrinkage threshold algorithm are used to solve so as to identify the tags from the clutter scatterers.

[0124] (26)

[0125] (27)

[0126] To further illustrate the tag identification effect of Steps 101 - 103 in the present embodiment in practical applications, taking three tags and a single copper clutter scatterer of the same size as an example, the identification and reconstruction results are as Figure 3 shown, where the white curve represents the ground truth boundary of the clutter scatterer, and the gray curve represents the ground truth boundary of the tag:

[0127] In Figure 3 (a)-(h), the respective peak signal-to-noise ratio (PSNR) and structural similarity value (SSIM) reconstructed based on the reflection coefficients are: (a) (PSNR = 22.70 dB, SSIM = 0.97), (b) (PSNR = 27.70 dB, SSIM = 0.99), (c) (PSNR = 27.76 dB, SSIM = 0.99)), (d) (PSNR = 31.84 dB, SSIM = 0.99), (e) (PSNR = 28.10 dB, SSIM = 0.98), (f) (PSNR = 28.09 dB, SSIM = 0.99), (g) (PSNR = 27.49 dB, SSIM = 0.98) and (h) PSNR = 25.37 dB, SSIM = 0.97);

[0128] As Figure 3 (a) shows, three tags and a clutter scatterer can be accurately reconstructed in the sensing stage; in the identification stage, as Figure 3As shown in (b)-(d), each tag can be individually identified; in addition, as Figure 3 shown in (e)-(g), any two tags can be well reconstructed and identified; finally, as Figure 3 shown in (h), all three tags can be simultaneously identified and distinguished;

[0129] These results indicate that various combinations of multiple tags can be accurately reconstructed in the integrated sensing and backscatter communication system by the above method.

[0130] It can be understood that the inverse scattering technique reconstructs the spatial distribution of physical properties by inverting the measured scattering data. However, the inverse scattering problems (ISPs) are widely regarded as ill-posed and non-linear. Existing techniques, such as the linear Born approximation (BA), Rytov approximation (RA), extended Rytov approximation (xRA), etc., provide powerful techniques for dealing with noise and errors in inverse scattering, simplify the calculation, and facilitate imaging and positioning tasks. But these inverse scattering techniques are usually for clutter scatterers with time-invariant reflectivity to provide high-fidelity imaging and precise positioning. In this embodiment, the inverse scattering technique is ingeniously applied to scatterers with time-varying reflectivity, so that in a cluttered environment, the inverse scattering technique can not only be used to sense tags and clutter scatterers, but also be used to accurately locate and identify individual or combined tags.

[0131] Step 104: When the transmitting antenna activates the tag, the tag uses binary phase shift keying to respond to the activation signal to transmit a data signal to the receiving antenna, and collect the data reception voltage of the receiving antenna.

[0132] It should be noted that after the tag sends a pilot signal for sensing and identification, backscatter communication can be performed. When the transmitting antenna transmits an activation signal to the tag, the tag can obtain energy from it to activate its circuit. The activation signal can be understood as a continuous wave carrier signal, and its main purpose is to provide energy for the passive tag and serve as a stable reference signal so that the tag can modulate it. And the tag modulates it into a data signal and reflects it to the receiving antenna by changing its impedance through binary phase shift keying (BPSK) according to the data to be transmitted; specifically, the tag switches between open-circuit and short-circuit load impedances, and the k-th bit mapping symbol transmitted by the tag is represented as , and for each bit mapping symbol, we can measure the data reception voltage at the receiving antenna of different transmitting antennas .

[0133] Step 105: Respectively use the reflection coefficient of the tag antenna mode and the combined reflection coefficient of the clutter tag structure to correspondingly determine the tag antenna mode data voltage component and the combined data voltage component of the clutter tag structure of the data signal.

[0134] It should be noted that according to Equation (18) and Equation (19), based on the field radiated when the receiving antenna operates in the transmission mode of unit excitation , and the incident field of the transmitting antenna associated with the data signal, that is, the incident field of the transmitting antenna when transmitting the activation signal, the corresponding tag antenna mode data voltage component and the combined data voltage component of the clutter tag structure are calculated using the reflection coefficient of the tag antenna mode and the combined reflection coefficient of the clutter tag structure.

[0135] Step 106: Jointly demodulate the data reception voltage, the combined data voltage component of the clutter tag structure, and the tag antenna mode data voltage component to obtain the bit-mapped symbol of the data signal.

[0136] Step 106 includes the following sub-steps:

[0137] S31: Perform a subtraction operation on the data reception voltage and the combined data voltage component of the clutter tag structure to obtain the received signal of the receiving antenna;

[0138] S32: Input the received signal and the tag antenna mode data voltage component into a preset reverse communication model and perform demodulation through maximum ratio combining to obtain the bit-mapped symbol of the data signal.

[0139] It should be noted that we can combine the measured data reception voltages into a data reception voltage vector, denoted as , where , using Equation (17), we can relate and as follows:

[0140] (28)

[0141] Next, by removing the combined voltage component vector of the clutter and the tag structure mode in to define the received signal , that is, , and considering the influence of noise , a functional relationship between the received signal and the bit-mapped symbol is constructed, and the backscatter communication model is obtained as:

[0142] (29)

[0143] In the formula, is the The received signal of a bit-mapped symbol is the voltage component vector of the tag antenna mode is the th bit-mapped symbol is the th bit-mapped symbol noise

[0144] Furthermore, the maximum ratio combining (MRC) algorithm is used, that is, the optimal linear combiner enhances symbol detection to further improve communication performance and demodulates to obtain , where

[0145] (30)

[0146] In the formula is the combination of the received signals

[0147] To further illustrate the scattering communication performance of this embodiment in practical applications, we consider a specific scenario. Taking the existence of a single copper dipole antenna and a single copper clutter scatterer in the DOI as an example, the total received response voltage V includes the structural mode of the tag, clutter scattering, and the antenna mode of the tag. The magnitude cases in open-circuit and short-circuit are as Figure 4 (a) shown Figure 4 (b) is the magnitude distribution of the clutter scattering and the structural mode of the tag extracted based on Equation (22) , and the magnitude distribution of the antenna mode of the tag is extracted in open-circuit and short-circuit cases as Figure 4 (c) shown, while the magnitudes of the antenna modes in open-circuit and short-circuit cases are the same, as Figure 4 (d) shown. The phase difference between open-circuit and short-circuit cases always maintains a value of π or -π. Through BPSK modulation, this phase difference can be effectively utilized for data communication

[0148] In addition to this analysis, we also evaluate the BER performance of the proposed backscatter communication through 105 Monte Carlo simulation experiments. The relationship between the uplink bit error rate BER performance of the backscatter communication using the MRC technique and the signal-to-noise ratio SNR is as Figure 5 shown. It can be seen that our simulation results are in good agreement with the theoretical BER performance. The evaluation process of the uplink bit error rate includes

[0149] (31)

[0150] In the formula, is the bit error rate, is the Q function (also known as the right-tail function of the standard normal distribution), is the population standard deviation.

[0151] In this embodiment, by modulating the open and short circuit states of the tag, the pilot voltage component of the tag antenna pattern and the combined pilot voltage component of the clutter tag structure are respectively extracted. The tag and the clutter scatterer are sensed based on the combined pilot voltage component of the clutter tag structure, and the tag antenna pattern pilot voltage component is used for tag identification. Applying the inverse scattering and compressive sensing algorithms for sensing and identification can recover the high-dimensional imaging information and reduce the number of required transceivers. Combining the imaging method based on inverse scattering with modulating the impedance of the tag to implement backscatter communication enables the integrated sensing and backscatter communication system to achieve simultaneous localization, identification, and backscatter communication of the tag in a chaotic environment, improving the performance of backscatter communication.

[0152] Please refer to Figure 6 , Figure 6 which is the structural block diagram of an integrated sensing and backscatter communication device based on inverse scattering provided by an embodiment of the present invention.

[0153] An integrated sensing and backscatter communication device based on inverse scattering provided by the present invention includes:

[0154] A pilot modulation module 601, configured to modulate the tag to be in an open state to generate an open-circuit pilot signal of the pilot signal and in a short-circuit state to generate a short-circuit pilot signal of the pilot signal after transmitting a pilot signal to the tag through a transmitting antenna, and backscatter the open-circuit pilot signal and the short-circuit pilot signal to a receiving antenna;

[0155] A pilot voltage determination module 602, configured to determine the pilot voltage component of the tag antenna pattern and the combined pilot voltage component of the clutter tag structure according to the open-circuit pilot received voltage generated by the receiving antenna based on the open-circuit pilot signal and the short-circuit pilot received voltage generated by the short-circuit pilot signal;

[0156] A reflection coefficient determination module 603, configured to respectively construct an underdetermined linear equation set based on the pilot voltage component of the tag antenna pattern and the combined pilot voltage component of the clutter tag structure by using a compressive sensing algorithm and perform optimization and solution, and correspondingly determine the reflection coefficient of the tag antenna pattern and the combined reflection coefficient of the clutter tag structure;

[0157] A signal transmission and acquisition module 604, configured to, when the transmitting antenna activates the tag, transmit a data signal to the receiving antenna through the tag by using binary phase shift keying and acquire the data received voltage of the receiving antenna;

[0158] A signal voltage calculation module 605, configured to respectively use the reflection coefficient of the tag antenna mode and the combined reflection coefficient of the clutter tag structure to correspondingly determine the tag antenna mode data voltage component and the combined data voltage component of the clutter tag structure of the data signal;

[0159] A signal demodulation module 606, configured to perform signal demodulation by combining the data reception voltage, the combined data voltage component of the clutter tag structure, and the tag antenna mode data voltage component to obtain the bit mapping symbol of the data signal.

[0160] Optionally, the pilot voltage determination module 602 is specifically configured to:

[0161] Collect the open-circuit pilot reception voltage generated by the receiving antenna based on the open-circuit pilot signal and the short-circuit pilot reception voltage generated based on the short-circuit pilot signal;

[0162] Take half of the difference between the open-circuit pilot reception voltage and the short-circuit pilot reception voltage to obtain the tag antenna mode pilot voltage component;

[0163] Perform an average operation on the open-circuit pilot reception voltage and the short-circuit pilot reception voltage to obtain the combined pilot voltage component of the clutter tag structure.

[0164] Optionally, the reflection coefficient determination module 603 is specifically configured to:

[0165] Construct a first underdetermined linear equation set about the combined reflection coefficient of the clutter tag structure based on the combined voltage component of the clutter tag structure through a compressive sensing algorithm;

[0166] Use a two-step iterative shrinkage threshold algorithm to optimize and solve the first underdetermined linear equation set to determine the combined reflection coefficient of the clutter tag structure;

[0167] Construct a second underdetermined linear equation set about the reflection coefficient of the tag antenna mode based on the voltage component of the tag antenna mode through a compressive sensing algorithm;

[0168] Use a two-step iterative shrinkage threshold algorithm to optimize and solve the second underdetermined linear equation set to determine the reflection coefficient of the tag antenna mode.

[0169] Optionally, the signal demodulation module 606 is specifically configured to:

[0170] Perform a subtraction operation on the data reception voltage and the combined data voltage component of the clutter tag structure to obtain the received signal of the receiving antenna;

[0171] Input the received signal and the tag antenna mode data voltage component into a preset reverse communication model and perform demodulation through maximum ratio combining to obtain the bit mapping symbol of the data signal.

[0172] Optionally, the reverse communication model is specifically:

[0173] ;

[0174] In the formula, is the received signal of the th bit mapping symbol, is the vector of the voltage component of the tag antenna pattern, is the th bit mapping symbol, is the th bit mapping symbol of noise.

[0175] Optionally, the determination process of the data voltage component of the tag antenna pattern is specifically:

[0176] ;

[0177] The determination process of the combined data voltage component of the clutter tag structure is specifically:

[0178] ;

[0179] In the formula, is the th transmitting antenna, is the th receiving antenna, is the voltage component of the tag antenna pattern, is an imaginary number, is the angular frequency, is the vacuum permeability, is the normalization factor, is the region of interest where the tag and clutter scatterers are located, is the th receiving antenna's radiated field when operating in the transmitting mode of unit excitation, is the th transmitting antenna's incident field generated at position , is the tag antenna pattern reflection coefficient, is the area of each spatial pixel in the region of interest, is the combined voltage component of the clutter tag structure, is the combined reflection coefficient of the clutter tag structure.

[0180] An embodiment of the present invention also provides a computer device, including a memory and a processor, and a computer program is stored in the memory; when the computer program is executed by the processor, the processor is caused to execute the steps of the integrated sensing and backscatter communication method based on inverse scattering in any of the above embodiments.

[0181] An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program / instructions are stored. When the computer program / instructions are executed by a processor, the steps of the integrated sensing and backscatter communication method based on inverse scattering in any of the above embodiments are implemented.

[0182] An embodiment of the present invention further provides a computer program product, including a computer program / instructions. When the computer program / instructions are executed by a processor, the steps of the integrated sensing and backscatter communication method based on inverse scattering in any of the above embodiments are implemented.

[0183] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described devices and modules can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein.

[0184] In several embodiments provided by the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some interfaces. The indirect coupling or communication connection of the devices or units can be in an electrical, mechanical or other form.

[0185] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0186] In addition, in each embodiment of the present invention, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0187] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0188] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An integrated sensing and backscatter communication method based on inverse scattering, characterized in that, Including: After transmitting a pilot signal to the tag through a transmitting antenna, modulating the tag to be in an open state to generate an open-circuit pilot signal of the pilot signal and in a short-circuit state to generate a short-circuit pilot signal of the pilot signal, and backscattering the open-circuit pilot signal and the short-circuit pilot signal to a receiving antenna; Determining a tag antenna mode pilot voltage component and a clutter tag structure combination pilot voltage component according to an open-circuit pilot received voltage generated by the receiving antenna based on the open-circuit pilot signal and a short-circuit pilot received voltage generated by the short-circuit pilot signal; Using a compressive sensing algorithm to respectively construct an underdetermined linear equation set based on the tag antenna mode pilot voltage component and the clutter tag structure combination pilot voltage component and perform optimization and solution, and correspondingly determining a tag antenna mode reflection coefficient and a clutter tag structure combination reflection coefficient; When the transmitting antenna activates the tag, transmitting a data signal to the receiving antenna by the tag using binary phase shift keying, and collecting a data received voltage of the receiving antenna; Respectively using the tag antenna mode reflection coefficient and the clutter tag structure combination reflection coefficient to correspondingly determine a tag antenna mode data voltage component and a clutter tag structure combination data voltage component of the data signal; Jointly demodulating the data received voltage, the clutter tag structure combination data voltage component and the tag antenna mode data voltage component to obtain a bit mapping symbol of the data signal.

2. The integrated sensing and backscatter communication method based on inverse scattering according to claim 1, wherein The determining a tag antenna mode pilot voltage component and a clutter tag structure combination pilot voltage component according to an open-circuit pilot received voltage generated by the receiving antenna based on the open-circuit pilot signal and a short-circuit pilot received voltage generated by the short-circuit pilot signal includes: Collecting an open-circuit pilot received voltage generated by the receiving antenna based on the open-circuit pilot signal and a short-circuit pilot received voltage generated by the short-circuit pilot signal; Taking half of the difference between the open-circuit pilot received voltage and the short-circuit pilot received voltage to obtain a tag antenna mode pilot voltage component; Performing an averaging operation on the open-circuit pilot received voltage and the short-circuit pilot received voltage to obtain a clutter tag structure combination pilot voltage component.

3. The integrated sensing and backscatter communication method based on inverse scattering according to claim 1, wherein The using a compressive sensing algorithm to respectively construct an underdetermined linear equation set based on the tag antenna mode voltage component and the clutter tag structure combination voltage component and perform optimization and solution, and correspondingly determining a tag antenna mode reflection coefficient and a clutter tag structure combination reflection coefficient includes: Constructing a first underdetermined linear equation set about a clutter tag structure combination reflection coefficient based on the clutter tag structure combination voltage component through a compressive sensing algorithm; Using a two-step iterative shrinkage threshold algorithm to perform optimization and solution on the first underdetermined linear equation set to determine a clutter tag structure combination reflection coefficient; Constructing a second underdetermined linear equation set about a tag antenna mode reflection coefficient based on the tag antenna mode voltage component through a compressive sensing algorithm; Using a two-step iterative shrinkage threshold algorithm to perform optimization and solution on the second underdetermined linear equation set to determine a tag antenna mode reflection coefficient.

4. The integrated sensing and backscatter communication method based on inverse scattering according to claim 1, wherein Demodulating the signal by combining the data reception voltage, the clutter tag structure combined data voltage component, and the tag antenna pattern data voltage component to obtain the bit mapping symbol of the data signal, including: Performing a subtraction operation on the data reception voltage and the clutter tag structure combined data voltage component to obtain the received signal of the receiving antenna; Inputting the received signal and the tag antenna pattern data voltage component into a preset reverse communication model and demodulating by maximum ratio combining to obtain the bit mapping symbol of the data signal.

5. The integrated sensing and backscatter communication method based on inverse scattering according to claim 4, wherein The specific reverse communication model is: ； Wherein, is the received signal of the th bit-mapped symbol, is the tag antenna mode voltage component vector, is the th bit-mapped symbol, is the noise of the th bit-mapped symbol.

6. The integrated sensing and backscatter communication method based on inverse scattering according to claim 1, wherein The specific process for determining the tag antenna pattern data voltage component is: ； The specific process for determining the clutter tag structure combined data voltage component is: ； wherein, is the th transmitting antenna, is the th receiving antenna, is the voltage component of the tag antenna mode, is an imaginary number, is the angular frequency, is the magnetic permeability of vacuum, is the normalization factor, is the region of interest where the tag and clutter scatterers are located, is the th field radiated by the receiving antenna when operating in the transmitting mode of unit excitation, is the th incident field generated by the transmitting antenna at the position , is the reflection coefficient of the tag antenna mode, is the area of each spatial pixel in the region of interest, is the combined voltage component of the clutter tag structure, is the combined reflection coefficient of the clutter tag structure.

7. An integrated sensing and backscatter communication device based on inverse scattering, characterized in that, Including: A pilot modulation module, configured to transmit a pilot signal to a tag through a transmitting antenna, modulate the tag to be in an open state to generate an open-circuit pilot signal of the pilot signal and in a short-circuit state to generate a short-circuit pilot signal of the pilot signal, and backscatter the open-circuit pilot signal and the short-circuit pilot signal to the receiving antenna; A pilot voltage determination module, configured to determine a tag antenna pattern pilot voltage component and a clutter tag structure combined pilot voltage component according to the open-circuit pilot reception voltage generated by the receiving antenna based on the open-circuit pilot signal and the short-circuit pilot reception voltage generated by the short-circuit pilot signal; A reflection coefficient determination module, configured to respectively construct an underdetermined linear equation set based on the tag antenna pattern pilot voltage component and the clutter tag structure combined pilot voltage component by using a compressive sensing algorithm and perform optimization and solution to correspondingly determine a tag antenna pattern reflection coefficient and a clutter tag structure combined reflection coefficient; A signal transmission and acquisition module, configured to, when the transmitting antenna activates the tag, transmit a data signal to the receiving antenna through the tag by using binary phase shift keying and acquire the data reception voltage of the receiving antenna; A signal voltage calculation module, configured to respectively use the tag antenna pattern reflection coefficient and the clutter tag structure combined reflection coefficient to correspondingly determine the tag antenna pattern data voltage component and the clutter tag structure combined data voltage component of the data signal; A signal demodulation module, configured to demodulate the signal by combining the data reception voltage, the clutter tag structure combined data voltage component, and the tag antenna pattern data voltage component to obtain the bit mapping symbol of the data signal.

8. A computer device, characterized in that, Including a memory and a processor, where a computer program is stored in the memory, and when the computer program is executed by the processor, the processor executes the steps of the integrated sensing and backscatter communication method based on inverse scattering according to any one of claims 1-6.

9. A computer-readable storage medium having computer programs / instructions stored thereon, characterized in that, When the computer program / instructions are executed by the processor, the steps of the integrated sensing and backscatter communication method based on inverse scattering according to any one of claims 1-6 are implemented.

10. A computer program product, comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, the steps of the integrated sensing and backscatter communication method based on inverse scattering according to any one of claims 1-6 are implemented.

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