A phase-free integrated sensing and backscattering communication method and related device based on inverse scattering

Abstract

This invention discloses a phaseless integrated sensing and backscattering communication method and related apparatus based on backscattering. In this invention, the load impedance of the tag is dynamically modulated, enabling the receiving antenna to receive pilot signals under different modulation states to enhance backscattering. The power components of the clutter tag structure combination and the tag antenna power components are estimated based on the RSSI of the acquired pilot signals, thereby sensing and identifying the tag. Then, the tag uses ASK modulation to transmit data signals to the receiving antenna, the received RSSI of the receiving antenna is acquired, and a zero-forcing algorithm is used for signal demodulation, effectively enhancing the reliability of backscattering communication.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a phaseless integrated sensing and backscattering communication method and related apparatus based on backscattering. Background Technology

[0002] Backscatter communication effectively reduces energy consumption caused by the rapid development of the Internet of Things (IoT). It enables low-power data transmission by using reflected radio frequency signals from the environment or dedicated sources. Since current transmission power requirements are as low as nanowatts to microwatts, backscattering technology is particularly suitable for energy-constrained applications. Therefore, integrated sensing and communication (ISAC) systems have attracted significant attention. They can further improve efficiency by combining sensing and communication functions, optimizing spectrum and hardware usage, reducing costs, and supporting location-aware and environment-aware applications. In this context, precise positioning using passive tag antennas is crucial for location-based services, enabling automatic target identification and applications in biomedical systems and environmental monitoring. Therefore, integrating positioning into backscattering systems has become a major research focus.

[0003] Existing indoor positioning methods (such as Time of Arrival (ToA), Angle of Arrival (AoA), and Direction of Arrival (DoA)) are widely used but have significant limitations. While these methods can achieve precise positioning, they require multiple receivers to determine the location by identifying the intersection of detection directions. Synthetic aperture radar (SAR) technology can also be used for passive tag positioning, but its reliance on mechanical scanning greatly limits the imaging speed.

[0004] In contrast, phase-free imaging techniques, which rely on intensity measurements (such as Received Signal Strength Indicator (RSSI)), exhibit unique advantages in indoor radio frequency (RF) and microwave imaging. By eliminating the need for coherent phase information, this approach offers the advantage of reduced hardware complexity and cost, making phase-free techniques particularly suitable for the microwave band, where capturing accurate phase measurements is inherently challenging.

[0005] From an electromagnetic perspective, RSSI-based imaging is generally classified as an inverse scattering problem (ISP). Since ISPs are inherently ill-conditioned and nonlinear, methods such as the Born approximation (BA) and Rytov approximation (RA), contrastive source inversion, and nonlinear deep learning have been developed to address these challenges. Among these, nonlinear techniques, including subspace optimization and iterative methods such as the distorted wave Born iterative method (DBIM) and the distorted wave Rytov iterative method (DRIM), have made significant progress in reconstructing strongly scattering scenes. These methods have shown potential for high-fidelity imaging and accurate localization of clutter scatterers with time-invariant reflectivity. However, existing research on phaseless inverse scattering methods mainly focuses on static clutter scatterers, and their application to time-varying reflectivity has not been widely explored. This limitation hinders the full utilization of phaseless inverse scattering technology in integrated sensing and communication (ISAC) systems, thus affecting the poor detection accuracy of phaseless systems in cluttered environments and resulting in lower backscattering communication performance. Summary of the Invention

[0006] This invention provides a phaseless integrated sensing and backscatter communication method and related device based on backscattering, which solves the technical problems of poor tag detection accuracy and low backscatter communication performance in existing phaseless systems.

[0007] This invention provides a phase-free integrated sensing and backscattering communication method based on inverse scattering, the method comprising:

[0008] The tag transmits a pilot signal to the tag via a transmitting antenna, modulates the load impedance of the tag to generate a first pilot signal and a second pilot signal, and backscatters the first pilot signal and the second pilot signal to the receiving antenna.

[0009] The first pilot signal and the second pilot signal are received by the receiving antenna, and the first RSSI and the second RSSI are measured. Based on the first RSSI and the second RSSI, the power components of the clutter tag structure combination and the tag antenna power components are determined.

[0010] Based on the power components of the clutter tag structure combination and the power components of the tag antenna, the reflection coefficients of the clutter tag structure combination and the tag antenna are estimated respectively.

[0011] After the transmitting antenna senses and identifies the tag through the combined reflection coefficient of the clutter tag structure and the reflection coefficient of the tag antenna, the data signal is transmitted to the receiving antenna through ASK modulation of the tag, and the received RSSI of the receiving antenna is measured.

[0012] Based on the zero-forcing algorithm, the bit symbols of the data signal are obtained by demodulating the received RSSI, the combined power component of the clutter tag structure, and the power component of the tag antenna.

[0013] Optionally, the step of estimating the reflection coefficient of the clutter tag structure combination and the reflection coefficient of the tag antenna based on the combined power component of the clutter tag structure and the power component of the tag antenna, respectively, includes:

[0014] A first underdetermined equation is constructed based on the combined power components of the clutter tag structure using a compressed sensing algorithm. The first underdetermined equation is then solved using a two-step iterative shrinking threshold algorithm to obtain the reflection coefficient of the combined clutter tag structure.

[0015] A second underdetermined equation is constructed based on the power components of the tag antenna using a compressed sensing algorithm. The second underdetermined equation is then solved using a two-step iterative shrinking threshold algorithm to obtain the tag antenna reflection coefficient.

[0016] Optionally, the step of transmitting the tag by using the tag structure combined with the reflection coefficient and the tag antenna reflection coefficient to transmit a data signal to the receiving antenna via ASK modulation and measuring the received RSSI of the receiving antenna includes: after transmitting the tag by using the tag structure combined with the reflection coefficient to sense the clutter scatterer and the tag, and identifying the tag from the clutter scatterer via the tag antenna reflection coefficient, transmitting a data signal to the receiving antenna via ASK modulation and measuring the received RSSI of the receiving antenna.

[0017] Optionally, the step of obtaining the bit symbols of the data signal by demodulating the received RSSI, the clutter tag structure combined power component, and the tag antenna power component based on the zero-forcing algorithm includes:

[0018] The received RSSI is subtracted from the power component of the clutter tag structure to obtain the received signal of the receiving antenna.

[0019] The received signal from the receiving antenna and the power component of the tag antenna are input into a preset backscattering communication model and solved using a zero-forcing algorithm to obtain the decision reflection coefficient.

[0020] The average value of the reflection coefficient of the first pilot signal and the reflection coefficient of the second pilot signal is set as the decision threshold;

[0021] The decision reflection coefficient and the decision threshold are compared. If the decision reflection coefficient is greater than the decision threshold, the bit symbol of the demodulated data signal is bit 1; otherwise, the bit symbol of the demodulated data signal is bit 0.

[0022] Optionally, the first underdetermined equation is specifically:

[0023]

[0024] In the formula: Describing the l1 norm, This represents the reflection coefficient of the clutter tag structure combination. This indicates the combined power components of the clutter tag structure. Represents the measurement matrix;

[0025] The second underdetermined equation is as follows:

[0026]

[0027] In the formula: Indicates the tag antenna reflection coefficient. This indicates the power components of the tag antenna.

[0028] Optionally, the preset backscatter communication model is specifically as follows:

[0029]

[0030] In the formula: Indicates the first One received signal, Indicates the first A data symbol, Indicates the first Additive white Gaussian noise for each data symbol.

[0031] Optionally, the decision reflection coefficient is expressed as:

[0032]

[0033] In the formula: Indicates the first One decision reflection coefficient, This represents a linear detection matrix.

[0034] The present invention also provides a phase-free integrated sensing and backscattering communication device based on inverse scattering, comprising:

[0035] A modulation module is used to transmit pilot signals to the tag through a transmitting antenna, modulate the load impedance of the tag so that the tag generates a first pilot signal and a second pilot signal, and backscatter the first pilot signal and the second pilot signal to a receiving antenna;

[0036] The power component determination module is used to receive the first pilot signal and the second pilot signal through the receiving antenna, measure the first RSSI and the second RSSI, and determine the clutter tag structure combined power component and the tag antenna power component based on the first RSSI and the second RSSI.

[0037] The reflection coefficient estimation module is used to estimate the reflection coefficient of the clutter tag structure combination and the reflection coefficient of the tag antenna based on the power component of the clutter tag structure combination and the power component of the tag antenna, respectively.

[0038] The signal transmission module is used to transmit data signals to the receiving antenna through the tag using ASK modulation after the transmitting antenna senses and identifies the tag by combining the reflection coefficient of the clutter tag structure and the reflection coefficient of the tag antenna, and to measure the received RSSI of the receiving antenna.

[0039] The demodulation module is used to perform demodulation operations based on the zero-forcing algorithm, using the received RSSI, the clutter tag structure combined power component, and the tag antenna power component to obtain the bit symbols of the data signal.

[0040] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the phaseless integrated sensing and backscatter communication method as described above.

[0041] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the phaseless integrated sensing and backscatter communication method as described above.

[0042] As can be seen from the above technical solutions, the present invention has the following advantages:

[0043] A phase-free integrated sensing and backscattering communication method and related apparatus based on backscattering are disclosed. The method includes: transmitting a pilot signal to a tag via a transmitting antenna; modulating the load impedance of the tag to generate a first pilot signal and a second pilot signal, and backscattering the first pilot signal and the second pilot signal to a receiving antenna; receiving the first pilot signal and the second pilot signal via the receiving antenna, and measuring a first RSSI and a second RSSI; determining the clutter tag structure combined power component and the tag antenna power component based on the first RSSI and the second RSSI; estimating the clutter tag structure combined reflection coefficient and the tag antenna reflection coefficient based on the clutter tag structure combined power component and the tag antenna power component, respectively; after the transmitting antenna senses and identifies the tag through the clutter tag structure combined reflection coefficient and the tag antenna reflection coefficient, transmitting a data signal to the receiving antenna via ASK modulation using the tag, and measuring the received RSSI of the receiving antenna; and demodulating the received RSSI, the clutter tag structure combined power component, and the tag antenna power component based on a zero-forcing algorithm to obtain the bit symbols of the data signal.

[0044] In this invention, by dynamically modulating the load impedance of the tag, the reflection coefficient of the clutter tag structure combination and the reflection coefficient of the tag antenna are obtained, which can accurately sense and identify clutter scatterers and the tag; at the same time, the zero-forcing algorithm is used for signal demodulation, which can improve the reliability of backscatter communication, thereby solving the technical problems of poor tag detection accuracy and low backscatter communication performance of existing phaseless systems. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 A flowchart illustrating the steps of a phase-free integrated sensing and backscattering communication method based on inverse scattering, provided in an embodiment of the present invention;

[0047] Figure 2 A schematic diagram of a phase-free integrated sensing and backscattering communication system provided in an embodiment of the present invention;

[0048] Figure 3 A schematic diagram illustrating the sensing and identification results analysis of three tags and a closed clutter scatterer provided as an example of the present invention;

[0049] Figure 4 A schematic diagram of the scattering RSSI response of the receiving antenna provided as an example of the present invention;

[0050] Figure 5 Data symbols of ASK modulation under different signal-to-noise ratios provided as examples of the present invention Bit error rate performance of (k);

[0051] Figure 6 This is a structural block diagram of a phase-free integrated sensing and backscattering communication device based on inverse scattering, provided for an embodiment of the present invention. Detailed Implementation

[0052] This invention provides a phaseless integrated sensing and backscattering communication method and related apparatus based on backscattering, which solves the technical problems of poor tag detection accuracy and low backscattering communication performance in existing phaseless systems.

[0053] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0054] Please see Figure 1 This invention proposes a phase-free integrated sensing and backscattering communication method based on inverse scattering; the method includes:

[0055] Step 101: Transmit pilot signals to the tag through the transmitting antenna, modulate the load impedance of the tag to generate a first pilot signal and a second pilot signal, and backscatter the first pilot signal and the second pilot signal to the receiving antenna.

[0056] It should be noted that this invention is applied to phase-free integrated sensing and backscatter communication systems. Please refer to [link / reference]. Figure 2 This system integrates sensing and backscatter communication using backscatter technology, achieving accurate tag positioning and identification while also enabling backscatter communication.

[0057] Figure 2The phase-free integrated sensing and backscattering communication system constructed in this embodiment is suitable for typical indoor environments. In the figure, the test area DOI is arranged with multiple clutter scatterers and tags. The test area DOI covers an area of ​​Lx × Ly and is divided into an Nx × Ny pixel grid, where Nx = Lx / Δx and Ny = Ly / Δy. Nx represents the number of pixels in the x-direction, Δx represents the length occupied by each pixel in the x-direction, Ny represents the number of pixels in the y-direction, and Δy represents the length occupied by each pixel in the y-direction. Therefore, the length occupied by each pixel... The area.

[0058] Along the boundary B of the DOI, M=20 uniformly spaced transceivers operate at a frequency of 2.4 GHz. The spatial location of the transmitting antenna m is denoted by r. m The spatial position of the receiving antenna m' is represented by r. m’ This indicates that all antennas are located on boundary B. The distance between the transmitting antenna m and the test point n within the DOI is denoted as r. m,n The distance between the same test point n and the receiving antenna m' is denoted as r. n,m’ Since each node cannot act as both a transmitter and a receiver simultaneously, the system configuration... Independent measurements are taken, where M=20 and L represents the number of independent measurements for the transmitting and receiving antennas. Furthermore, the subscripts m and m' in subsequent calculations refer to parameters related to the transmitting and receiving antennas, respectively.

[0059] In the proposed system, each transmit antenna m generates a vertically polarized time-harmonic incident electric field, which propagates through the test point within the DOI and interacts with clutter scatterers. The total electric field generated by this interaction... It is the incident field and scattered field The superposition of can be expressed as:

[0060]

[0061] Furthermore, the scattering field at the DOI boundary The following can be calculated using the Lippmann-Schwinger integral equation:

[0062]

[0063] In the formula: For imaginary numbers, Angular frequency, Permeability of free space; Represents all location points All are located within the DOI area; Represents the Green's function. (·) denotes the zeroth-order Hankel function of the first kind. This represents the free space wavenumber.

[0064] In practical applications, the scattered fields in formulas (1) and (2) are captured by the receiving antenna m' and converted into voltage. Therefore, the Green's function involved in formula (2) can be converted into the electric field radiated by the receiving antenna m' in the unit excitation transmission mode, resulting in:

[0065]

[0066] in, This represents the voltage generated by the scattered field produced by the transmitting antenna m, received by the receiving antenna m'; a represents the normalization factor. This represents the electric field radiated by the receiving antenna m' in unit excitation transmission mode.

[0067] The inverse scattering problem aims to obtain from the measurement in equation (2) The relative permittivity distribution was estimated. However, solving formula (2) involves two unknowns. and This makes the problem neither well-indeterminate nor nonlinear.

[0068] To address this issue, this embodiment employs the RA (Rytov Approximation) approximation algorithm, which is particularly effective in phase-free frames.

[0069] According to the RA approximation algorithm, the transmitting antenna m is at position... The total field at the location is represented as:

[0070]

[0071] in, This represents the complex phase of the scattered field generated by the transmitting antenna m.

[0072] By using the Rytov transform to convert the total field into the logarithmic field, equation (4) can be reformulated as:

[0073]

[0074] By applying this transformation to voltage measurements and neglecting terms under weak scattering conditions Formula (3) can be reformulated as a linear problem, as shown below:

[0075]

[0076] in, The background voltage measurement (without clutter scatterers) is the value. Indicates at the receiving antenna The total voltage measured at this location (with clutter scattering); at this time Since it is the only unknown, the solution process is simplified.

[0077] To convert formula (6) into an exponential form applicable to the phaseless frame, formula (6) can be expressed as:

[0078]

[0079] Multiplying formula (7) by its complex conjugate and taking the logarithm to the base 10, we obtain the RSSI received power change (dB) as follows:

[0080]

[0081] In the formula: The power change is expressed in dB; thus, the RSSI change and the relative permittivity distribution are established. The linear relationship between them.

[0082] In antenna scattering theory, the scattered field from the tag is determined by the impedance matching between its antenna and the connected load impedance, a relationship described by the reflection coefficient:

[0083]

[0084] In the formula: Indicates antenna impedance The complex conjugate, This represents the load impedance; when the load impedance is matched to the complex conjugate of the antenna impedance, i.e. At this point, the reflection coefficient becomes zero.

[0085] Among them, for a certain reflection coefficient Related specific modulation symbol c q The corresponding load impedance can be expressed as:

[0086]

[0087] When the transmitting antenna m illuminates the tag, the tag located within the DOI area... The scattered field can be expressed as:

[0088]

[0089] in, The electric field corresponding to the structural mode of the tag, It is the field radiated by the tag's antenna mode. It is the scattered field of the tag antenna mode. It is the load impedance and the antenna impedance. It is the current when the conjugate complex number is matched.

[0090] It should be noted that for a tag, its scattered field includes two parts: the scattering field of the structural mode and the scattering field of the antenna mode. The scattering field of the tag's structural mode is not affected by the load impedance and is determined by physical properties such as shape, size, location, and composition. The scattering field of the tag's antenna mode depends on the load conditions and can be modulated to facilitate data transmission in backscattered communication, which makes it possible to identify tags from clutter scatterers.

[0091] For simplicity, when the DOI region contains tags and clutter scatterers, the scattering field of the clutter scatterers is denoted as... Then in formula (4) can be represented as:

[0092]

[0093] because and Regardless of the tag's load impedance, they can combine to form a constant field. .

[0094] Then, according to formulas (1) and (2), the relative permittivity distribution It can be decomposed into:

[0095]

[0096] In the formula, Associated with the structural modes of clutter scatterers and tags, This corresponds to the antenna mode of the tag.

[0097] Similarly, RSSI in formula (8) can be decomposed into:

[0098]

[0099] in, This represents the power associated with clutter scatterers and tag structure modes. This indicates the power associated with the tag antenna mode.

[0100] Combining this with formula (8), the specific expression for the decibel (dB) component decomposed by RSSI is the power associated with the clutter scatterer and the tag structure mode. The expression for the decibel (dB) is shown in Equation (15), which relates to the power of the tag antenna mode. The expression for the decibel (db) is shown in formula (16);

[0101]

[0102]

[0103] Combining formulas (15) and (16), the inverse problem can therefore be transformed into estimating the RSSI from the measured values. and This allows for the sensing and identification of clutter scatterers and tags, which helps to more accurately identify the location of the tags.

[0104] Therefore, this invention utilizes backscatter communication to extract... and This method enhances sensing and identification capabilities. The process begins by transmitting two pilot signals to the tag via a transmitting antenna; the two pilot signals correspond to the reflection coefficients, respectively. = and = Γ2, which are respectively related to the load impedance Z L1 and Z L2 The signal is related to and backscatters the first and second pilot signals to the receiving antenna.

[0105] Step 102: Receive the first pilot signal and the second pilot signal through the receiving antenna, and measure the first RSSI and the second RSSI; determine the clutter tag structure combined power component and the tag antenna power component based on the first RSSI and the second RSSI.

[0106] In this context, combined with formula (13), the RSSI received by these pilot signals can be expressed as:

[0107]

[0108]

[0109] in: Indicates the first RSSI, Indicates the second RSSI.

[0110] So, and This can be deduced as:

[0111]

[0112]

[0113] In the given In the case of independent measurements, It can form a clutter tag structure to combine power components Each element Similarly, there are tag antenna power components. Each element .

[0114] in , m=1,2...,M−1, m is determined by =1 + ceil (m / M), ..., M is determined. Although backscatter communication systems theoretically support higher-order modulation schemes, such as 4-ary or 8-ary modulation, in this embodiment, for simplicity, we consider... =0.5 and =1, where =1 indicates the strongest reflectivity (i.e., the maximum RSSI), while A value of 0.5 corresponds to a moderate level of reflection, indicating sufficient power difference, which facilitates subsequent detection and demodulation, and is also easy to implement in hardware.

[0115] Step 103: Based on the power components of the clutter tag structure combination and the tag antenna power components, estimate the reflection coefficient of the clutter tag structure combination and the reflection coefficient of the tag antenna, respectively.

[0116] This step specifically includes the following sub-steps:

[0117] Sub-step 1031 involves using a compressed sensing algorithm to construct a first underdetermined equation based on the combined power components of the clutter tag structure, and then solving the first underdetermined equation using a two-step iterative shrinking threshold algorithm to obtain the combined reflection coefficient of the clutter tag structure.

[0118] In the initial stage, it can be used To accurately sense clutter scatterers and tags, according to equation (15), the following is constructed:

[0119]

[0120] in, This represents the reflection coefficient of the clutter tag structure combination. ,Depend on Composed of all N positions; H represents the measurement matrix. Containing elements × .

[0121] Measurement from equation (21) China Resumption One direct method is to calculate The reversal makes However, this approach is usually not feasible because the L observations are not completely independent, leading to an ill-posed problem in which the number of observations is usually less than the number of unknowns N.

[0122] Therefore, matrix H is usually non-invertible. To address this issue, compressed sensing (CS) technology can be used for image reconstruction. For sparse objects or scatterers, a first underdetermined equation is constructed, and equation (21) can be restated as:

[0123]

[0124] In the formula: This represents the l1 norm.

[0125] Then, the two-step iterative shrinking threshold (TwIST) algorithm is used to solve equation (22). The TwIST algorithm iteratively updates the estimated reflectance coefficients by applying shrinking and thresholding operations, thereby achieving sparse reflectance coefficients. The recovery.

[0126] Sub-step 1032: The compressed sensing algorithm is used to construct a second underdetermined equation based on the tag antenna power components. The second underdetermined equation is solved by a two-step iterative shrinking threshold algorithm to obtain the tag antenna reflection coefficient.

[0127] because Reflection coefficients representing clutter scatterers and tag structure modes, combined with clutter tag structure reflection coefficients It can accurately detect clutter scatterers and tags. However, it only recovers the reflection coefficient of the clutter tag structure combination. This is insufficient to identify the tag from clutter scattering. To identify the tag, it is also necessary to recover the tag antenna reflection coefficient. .

[0128] In order to identify the labels, we focus on It isolates the contribution of the antenna mode, and according to equation (16), we have:

[0129]

[0130] In the formula: .

[0131] Similar to recovery A second underdetermined definite equation is constructed:

[0132]

[0133] Similarly, the TwIST algorithm is used to solve equation (24) so ​​that the label can be identified.

[0134] Step 104: After the transmitting antenna senses and identifies the tag by combining the reflection coefficient of the clutter tag structure and the reflection coefficient of the tag antenna, the data signal is transmitted to the receiving antenna by ASK modulation through the tag, and the received RSSI of the receiving antenna is measured.

[0135] Understandably, once the transmitting antenna senses and identifies the tag through the combination of the clutter tag structure's reflection coefficient and the tag antenna's reflection coefficient, it can enter the backscatter communication stage: the tag transitions to data transmission via backscatter communication, a process employing amplitude-shift keying (ASK) modulation, where the tag is at two load impedances Z. L1 and Z L2 Alternating between them, corresponding to the reflection coefficients respectively. and The k-th data symbol emitted by the tag is represented as .

[0136] For each transmitted data symbol, the RSSI received at the antenna is measured and represented as... vectors in = Based on the relationship in equation (14), the measurement is obtained for the first... Received RSSI The data symbols related to the transmission are as follows:

[0137]

[0138] Step 105: Based on the zero-forcing algorithm, demodulation is performed by receiving RSSI, clutter tag structure combined power components and tag antenna power components to obtain the data symbols of the data signal.

[0139] This step specifically includes the following sub-steps:

[0140] Sub-step 1051 involves subtracting the power component of the received RSSI from the clutter tag structure combination to obtain the received signal from the receiving antenna.

[0141] By from Remove clutter from the label structure combined power components Further defining the received signal y(k), we obtain ,in Indicates the first One received signal.

[0142] Sub-step 1052 involves inputting the received signal from the receiving antenna and the power component of the tag antenna into a preset backscattering communication model and solving it using a zero-forcing algorithm to obtain the decision reflection coefficient.

[0143] Considering noise effects, the pre-defined backscatter communication model can be expressed as:

[0144]

[0145] in, Indicates the first Additive white Gaussian noise (AWGN) of 1 data symbol, characterized by zero mean and covariance matrix σ. 2 L Here, This can be considered as the channel vector of a pre-defined backscattered communication model. This pre-defined backscattered communication model can operate as a single-input multiple-output (SIMO) system. Furthermore, it can be obtained during the sensing phase. Channel State Information (CSI).

[0146] To optimize symbol detection, the zero-forcing (ZF) technique is applied, and the linear detection matrix of the optimal linear detector is defined as follows: Therefore, the received signal after applying the detector and the decision reflection coefficient The relationship between them can be represented as:

[0147]

[0148] Sub-step 1053: Set the average value of the reflection coefficient of the first pilot signal and the reflection coefficient of the second pilot signal as the decision threshold.

[0149] Among them, the judgment threshold is defined as and midpoint .

[0150] Sub-step 1054: The decision reflection coefficient and the decision threshold are judged. If the decision reflection coefficient is greater than the decision threshold, the bit symbol of the demodulated data signal is bit 1; otherwise, the bit symbol of the demodulated data signal is bit 0.

[0151] Specifically, when The data symbol of the data signal is determined by the time of data determination. The demodulated data signal is identified by its bit symbol as bit 1, and vice versa. Demodulation yields bit 0.

[0152] Furthermore, to evaluate the performance of a backscatter communication system, the analytical bit error rate (BER) can be used for analysis. The analytical bit error rate (BER) is expressed as... , where Q(·) represents the Q function.

[0153] For example, the present invention also provides corresponding simulation experiments to verify the application performance of the present solution.

[0154] 1) Regarding sensing and recognition performance:

[0155] This example evaluates the sensing and identification capabilities of the proposed solution using three configurations: the first configuration includes one tag and one clutter scatterer; the second configuration includes two tags and one clutter scatterer; and the third configuration includes three tags and one clutter scatterer. Each configuration uses a copper dipole antenna with a radius of 10 mm (0.08λ) and a height of 56.5 mm (0.452λ) as the tag, with an antenna impedance of 75 ohms; modulation is performed with a load impedance of 225 ohms and infinity, corresponding to reflection coefficients of 0.5 and 1, respectively.

[0156] To evaluate the perception and recognition quality of the reconstructed images and compare them with the ground reality, we use Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity Index (SSIM). Higher PSNR values ​​or SSIM values ​​closer to 1 indicate better image quality. This analysis primarily focuses on the third configuration, namely the sensing and recognition results with multiple labels, such as... Figure 3 As shown.

[0157] The third configuration includes four tags and a nearby copper rectangular clutter scatterer, and the reconstruction result is as follows: Figure 3 As shown. In Figure 3 In the diagram, the blue curve represents the actual boundary of the clutter scatterer, while the green curve represents the tag boundary. During the sensing phase, Figure 3 (a) shows that the system accurately reconstructed the locations of all four tags and clutter scatterers. During the identification phase, the system successfully identified individual tags, such as... Figure 3 As shown in (b)-(e). Furthermore, various combinations of two or three labels can be reconstructed and identified, such as... Figure 3 As shown in (f)-(p). Finally, the system achieves simultaneous recognition of four types of labels, as follows: Figure 3 As shown in (q). These analytical results highlight the robustness of this scheme in cases involving multiple tags and clutter scatterers.

[0158] In summary, the reconstruction results demonstrate the effectiveness of the proposed phaseless system. By leveraging tag characteristics and the inverse scattering method, the phaseless system can accurately locate and identify multiple tags and clutter scatterers with a resolution of 100 mm (0.8λ). This capability is particularly valuable in challenging environments where clutter scatterers can interfere with accurate tag localization and identification.

[0159] 2) Regarding backscatter communication performance:

[0160] To verify the backscattering communication capability of the proposed system, we consider a scenario involving a single copper dipole antenna (tag) within a DOI and a copper clutter scatterer. The tag's load impedance is... =225 ohms and Modulation between 0 and ∞ corresponds to the theoretical reflection coefficients. =0.5 and Γ2=1. The total RSSI response includes contributions from the structural modes of the tag and clutter scatterers, as well as the tag's response under both impedance conditions ( =225 ohms and Antenna modes with =∞), such as Figure 4 As shown in (a). Figure 4 (b) presents the RSSI distributions for isolated structural modes of clutter scatterers and tags based on Equation (19). Furthermore, Figure 4 (c) shows the RSSI distribution of the isolated antenna mode of the tag under the same impedance conditions. To further analyze the system, Figure 4 (d) shows =225 ohms and The total RSSI value under the condition of ∞ is relative to The normalized RSSI ratio for the case of ∞ is shown to be stable at 1 or 0.5, which is in good agreement with the theoretical analysis. This expected change in RSSI provides a basis for reliable data communication using amplitude shift keying (ASK) modulation.

[0161] 107 experiments were conducted using Monte Carlo simulations to further analyze the bit error rate (BER) performance of the proposed phaseless integrated sensing and backscatter communication system. The uplink BER of the backscatter communication system using ZF technology for signal detection was also analyzed. The relationship between BER and signal-to-noise ratio is shown below. Figure 5 As shown in the figure, the simulation results agree well with the theoretical bit error rate results, verifying the accuracy and reliability of the system.

[0162] The present invention provides a phase-free integrated sensing and backscattering communication method based on inverse scattering, which has the following advantages:

[0163] 1. This invention can perform sensing and communication functions within a specified field of interest (DOI). By dynamically modulating the load impedance of the tag, it can distinguish between the tag and clutter scatterers, thereby achieving the separation and extraction of the structural and antenna modes of the Received Signal Strength Index (RSSI).

[0164] 2. A sparse-based approach combined with inverse scattering techniques is used to handle phaseless measurements. The RSSI corresponding to clutter scatterers and tag structure patterns is used for initial tag and clutter detection, while the RSSI corresponding to tag antenna structure patterns is used for accurate identification of individual tags.

[0165] 3. The extracted RSSI corresponding to the antenna pattern can be used to derive Channel State Information (CSI) to improve backscatter communication performance; the Zero Forcing (ZF) technique can be used to improve Bit Error Rate (BER) performance and thus improve communication reliability.

[0166] 4. Compared with traditional synthetic aperture radar imaging systems, this invention does not rely on phased arrays, mechanical and electronic scanning mechanisms, resulting in faster imaging speed and significantly reduced complexity.

[0167] 5. This solution can achieve powerful backscatter communication and tag sensing and identification simultaneously in complex environments without phase information.

[0168] Please see Figure 6 The present invention also provides a phase-free integrated sensing and backscattering communication device based on inverse scattering, comprising:

[0169] The modulation module 201 is used to transmit pilot signals to the tag through the transmitting antenna, modulate the load impedance of the tag so that the tag generates a first pilot signal and a second pilot signal, and backscatters the first pilot signal and the second pilot signal to the receiving antenna.

[0170] The power component determination module 202 is used to receive the first pilot signal and the second pilot signal through the receiving antenna, measure the first RSSI and the second RSSI, and determine the clutter tag structure combination power component and the tag antenna power component based on the first RSSI and the second RSSI.

[0171] The reflection coefficient estimation module 203 is used to estimate the reflection coefficient of the clutter tag structure combination and the reflection coefficient of the tag antenna based on the power components of the clutter tag structure combination and the power components of the tag antenna, respectively.

[0172] The signal transmission module 204 is used to transmit data signals to the receiving antenna by means of ASK modulation of the tag after the transmitting antenna senses and identifies the tag through the combination of the clutter tag structure reflection coefficient and the tag antenna reflection coefficient, and to measure the received RSSI of the receiving antenna.

[0173] The demodulation module 205 is used to perform demodulation operations based on the zero-forcing algorithm by receiving RSSI, clutter tag structure combined power components and tag antenna power components to obtain the bit symbols of the data signal.

[0174] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the phaseless integrated sensing and backscatter communication method described above.

[0175] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the phaseless integrated sensing and backscatter communication method described above.

[0176] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0177] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between apparatuses or units through some interfaces, and may be electrical, mechanical, or other forms.

[0178] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0179] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0180] If the integrated unit is implemented as 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 the 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 cause a computer device (which may be a personal computer, server, or 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 capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0181] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A phase-free integrated sensing and backscattering communication method based on inverse scattering, characterized in that, The method includes: The tag transmits a pilot signal to the tag via a transmitting antenna, modulates the load impedance of the tag to generate a first pilot signal and a second pilot signal, and backscatters the first pilot signal and the second pilot signal to the receiving antenna. The first pilot signal and the second pilot signal are received by the receiving antenna, and the first RSSI and the second RSSI are measured. Based on the first RSSI and the second RSSI, the power components of the clutter tag structure combination and the tag antenna power components are determined. Based on the power components of the clutter tag structure combination and the power components of the tag antenna, the reflection coefficients of the clutter tag structure combination and the tag antenna are estimated respectively. After the transmitting antenna senses and identifies the tag through the combined reflection coefficient of the clutter tag structure and the reflection coefficient of the tag antenna, the data signal is transmitted to the receiving antenna through ASK modulation of the tag, and the received RSSI of the receiving antenna is measured. Based on the zero-forcing algorithm, the bit symbols of the data signal are obtained by demodulating the received RSSI, the combined power component of the clutter tag structure, and the power component of the tag antenna.

2. The phase-free integrated sensing and backscattering communication method according to claim 1, characterized in that, The step of estimating the reflection coefficient of the clutter tag structure combination and the reflection coefficient of the tag antenna based on the combined power components of the clutter tag structure and the power components of the tag antenna, respectively, includes: A first underdetermined equation is constructed based on the combined power components of the clutter tag structure using a compressed sensing algorithm. The first underdetermined equation is then solved using a two-step iterative shrinking threshold algorithm to obtain the reflection coefficient of the combined clutter tag structure. A second underdetermined equation is constructed based on the power components of the tag antenna using a compressed sensing algorithm. The second underdetermined equation is then solved using a two-step iterative shrinking threshold algorithm to obtain the tag antenna reflection coefficient.

3. The phase-free integrated sensing and backscattering communication method according to claim 1, characterized in that, The step of transmitting the tag by sensing and identifying it through the combined reflection coefficient of the clutter tag structure and the tag antenna reflection coefficient, and then transmitting a data signal to the receiving antenna by ASK modulation of the tag, and measuring the received RSSI of the receiving antenna, includes: after transmitting the tag by sensing the clutter scatterer and the tag through the combined reflection coefficient of the clutter tag structure and identifying the tag from the clutter scatterer by the tag antenna reflection coefficient, transmitting a data signal to the receiving antenna by ASK modulation of the tag, and measuring the received RSSI of the receiving antenna.

4. The phase-free integrated sensing and backscatter communication method according to claim 1, characterized in that, The step of obtaining the bit symbols of the data signal by demodulating the received RSSI, the combined power component of the clutter tag structure, and the power component of the tag antenna based on the zero-forcing algorithm includes: The received RSSI is subtracted from the power component of the clutter tag structure to obtain the received signal of the receiving antenna. The received signal from the receiving antenna and the power component of the tag antenna are input into a preset backscattering communication model and solved using a zero-forcing algorithm to obtain the decision reflection coefficient. The average value of the reflection coefficient of the first pilot signal and the reflection coefficient of the second pilot signal is set as the decision threshold; The decision reflection coefficient and the decision threshold are compared. If the decision reflection coefficient is greater than the decision threshold, the bit symbol of the demodulated data signal is bit 1; otherwise, the bit symbol of the demodulated data signal is bit 0.

5. The phase-free integrated sensing and backscattering communication method according to claim 2, characterized in that, The first underdetermined equation is specifically as follows: In the formula: Describing the l1 norm, This represents the reflection coefficient of the clutter tag structure combination. This indicates the combined power components of the clutter tag structure. Represents the measurement matrix; The second underdetermined equation is as follows: In the formula: Indicates the tag antenna reflection coefficient. This indicates the tag antenna power component.

6. The phase-free integrated sensing and backscattering communication method according to claim 4, characterized in that, The preset backscatter communication model is specifically as follows: In the formula: Indicates the first One received signal, Indicates the first A data symbol, Indicates the first Additive white Gaussian noise for each data symbol.

7. The phase-free integrated sensing and backscattering communication method according to claim 6, characterized in that, The decision reflection coefficient is expressed as: In the formula: Indicates the first One decision reflection coefficient, This represents a linear detection matrix.

8. A phase-free integrated sensing and backscattering communication device based on backscattering, characterized in that, include: A modulation module is used to transmit pilot signals to the tag through a transmitting antenna, modulate the load impedance of the tag so that the tag generates a first pilot signal and a second pilot signal, and backscatter the first pilot signal and the second pilot signal to a receiving antenna; The power component determination module is used to receive the first pilot signal and the second pilot signal through the receiving antenna, measure the first RSSI and the second RSSI, and determine the clutter tag structure combined power component and the tag antenna power component based on the first RSSI and the second RSSI. The reflection coefficient estimation module is used to estimate the reflection coefficient of the clutter tag structure combination and the reflection coefficient of the tag antenna based on the power component of the clutter tag structure combination and the power component of the tag antenna, respectively. The signal transmission module is used to transmit data signals to the receiving antenna through the tag using ASK modulation after the transmitting antenna senses and identifies the tag by combining the reflection coefficient of the clutter tag structure and the reflection coefficient of the tag antenna, and to measure the received RSSI of the receiving antenna. The demodulation module is used to perform demodulation operations based on the zero-forcing algorithm, using the received RSSI, the clutter tag structure combined power component, and the tag antenna power component to obtain the bit symbols of the data signal.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the phaseless integrated sensing and backscatter communication method as described in any one of claims 1-7.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the phaseless integrated sensing and backscatter communication method as described in any one of claims 1-7.

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