Synchronous perception and backscatter communication method and device based on spatial modulation and backscatter

Abstract

The invention discloses a synchronous perception and backscatter communication method and device based on spatial modulation and backscatter, and relates to the technical field of communication, and the method comprises the steps: transmitting a pilot signal to a label through a transmitting array, modulating the load impedance of the label, and then backscattering the signal to a receiving array; the receiving voltage generated by the receiving array and the original channel matrix are adopted to determine the reflectivity of the clutter tag and the reflectivity of the tag antenna; positioning and identifying the tag based on the reflectivity of the clutter tag; extracting a target channel matrix for constructing a tag from the original channel matrix according to the tag antenna reflectivity; performing spatial modulation on the information bits through a transmitting array, generating constellation symbols and determining an activation label; and backscattering the constellation symbols to the receiving array through the activation tag by adopting the transmitting array, and demodulating and decoding by combining the target channel matrix to output information bits. The backscatter label is accurately positioned and identified in a disordered environment, and spatial modulation is integrated into backscatter communication, so that the reliability of backscatter communication is improved.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a backscattering communication method and device based on spatial modulation and inverse scattering. Background Art

[0002] Integrated Sensing and Communication (ISAC) is a potential solution for future wireless systems due to its higher spectral and energy efficiency, lower hardware complexity, and reduced signal processing overhead. However, the rapid growth of wireless devices has brought about significant power challenges. Limited battery capacity limits device lifespan and communication power consumption often needs to be reduced to below 1 mW. In addition, environmental issues related to battery disposal further highlight the importance of energy-efficient communications. Backscatter communications, with its extremely low power consumption, transmits data by reflecting existing RF signals, eliminating power-intensive active components, significantly improving energy efficiency, and reducing hardware costs, providing an effective solution to these challenges.

[0003] In the ISAC framework, accurate positioning of backscatter tags is crucial. Traditional positioning methods based on arrival time, arrival angle, and arrival direction are usually insufficient to achieve accurate positioning, especially in short-range or cluttered scenarios. Inverse scattering technology can reconstruct the scatterer characteristics by inverting the measured scattered signals to achieve accurate positioning. However, it also faces inherent ill-posedness and nonlinear challenges, making accurate reconstruction difficult and resulting in low reliability of backscatter communication. Summary of the Invention

[0004] The present invention provides a synchronous sensing and backscattering communication method and device based on spatial modulation and backscattering, which solves the problem of low positioning and recognition accuracy of backscattering tags under the existing ISAC framework, resulting in low reliability of backscattering communication.

[0005] A first aspect of the present invention provides a synchronous sensing and backscattering communication method based on spatial modulation and inverse scattering, involving a transmitting array, a receiving array, and a region of interest, wherein the region of interest contains clutter scatterers and tags; the method comprises:

[0006] After transmitting the pilot signal to the tag through the transmitting array, modulating the load impedance of the tag to generate multiple modulated pilot signals of the pilot signal and backscattering them to the receiving array;

[0007] The clutter tag reflectivity and the tag antenna reflectivity are determined by using a receiving array based on the received voltage generated corresponding to each received modulated pilot signal and the original channel matrix of the region of interest;

[0008] Locating a first position of a clutter scatterer and a tag based on the clutter tag reflectivity, and identifying the tag from the first position using the tag antenna reflectivity;

[0009] Extracting and constructing a target channel matrix of the tag from the original channel matrix according to the tag antenna reflectivity;

[0010] The information bits to be transmitted are spatially modulated by the transmitting array to generate constellation symbols and determine the active tag from each tag;

[0011] The constellation symbol is backscattered to a receiving array through an activated tag by a transmitting array, and the receiving array demodulates and decodes the received signal of the constellation symbol and the target channel matrix to output information bits.

[0012] Optionally, the modulated pilot signal includes an open-circuit pilot signal and a short-circuit pilot signal; after transmitting the pilot signal to the tag through the transmitting array, modulating the load impedance of the tag to generate multiple modulated pilot signals of the pilot signal and backscattering them to the receiving array, including:

[0013] Transmitting a pilot signal to the tag via a transmitting antenna;

[0014] The load impedance of the modulation tag is in an open circuit state, and an open circuit pilot signal corresponding to the received pilot signal is generated by the tag;

[0015] After the load impedance of the modulation tag is in a short-circuit state, a short-circuit pilot signal corresponding to the received pilot signal is generated by the tag;

[0016] The open-circuit pilot signal and the short-circuit pilot signal are backscattered to a receiving array.

[0017] Optionally, the determining of the clutter tag reflectivity and the tag antenna reflectivity by using the receiving array based on the received voltage generated corresponding to each received modulated pilot signal and the original channel matrix of the region of interest includes:

[0018] measuring an open-circuit receiving voltage of the receiving array when it receives an open-circuit pilot signal and a short-circuit receiving voltage of the receiving array when it receives a short-circuit pilot signal;

[0019] Determining a clutter tag voltage component and a tag antenna voltage component using the open-circuit receiving voltage and the short-circuit receiving voltage;

[0020] According to the compressed sensing algorithm and the two-step iterative shrinkage threshold algorithm, the output clutter tag reflectivity is solved based on the clutter tag voltage component and the original channel matrix of the region of interest;

[0021] The output tag antenna reflectivity is solved based on the tag antenna voltage component and the original channel matrix through a compressed sensing algorithm and a two-step iterative shrinkage threshold algorithm.

[0022] Optionally, the process of determining the original channel matrix includes:

[0023] Perform electromagnetic simulation on the region of interest to determine the incident electric field of the transmitting array and the receiving array at each position in the region of interest;

[0024] The incident electric field at each position is used to calculate the corresponding channel vector, and the channel vectors are combined to form an original channel matrix.

[0025] Optionally, the determining of the clutter tag voltage component and the tag antenna voltage component by using the open-circuit receiving voltage and the short-circuit receiving voltage includes:

[0026] Performing a mean operation on the sum of the open-circuit receiving voltage and the short-circuit receiving voltage to determine a clutter tag voltage component;

[0027] Performing a mean operation on the difference between the open-circuit receiving voltage and the short-circuit receiving voltage, and outputting a tag antenna voltage component.

[0028] Optionally, the received signal specifically includes:

[0029] ;

[0030] in, , ;

[0031] Where, To receive the signal, is the target channel matrix, is the transmission vector of the activation tag based on the constellation symbol, is additive white Gaussian noise, For the tags, For the The constellation symbol transmitted by each tag, is the total number of labels, For expectations, is the conjugate transpose.

[0032] A second aspect of the present invention provides a synchronous sensing and backscattering communication device based on spatial modulation and inverse scattering, involving a transmitting array, a receiving array, and a region of interest, wherein the region of interest contains clutter scatterers and tags; comprising:

[0033] A pilot scattering module is used to transmit a pilot signal to the tag through the transmitting array, modulate the load impedance of the tag to generate multiple modulated pilot signals of the pilot signal and scatter them back to the receiving array;

[0034] A reflectivity determination module is used to determine the clutter tag reflectivity and the tag antenna reflectivity using a receiving voltage generated by the receiving array based on each received modulated pilot signal and an original channel matrix of the region of interest;

[0035] a tag sensing module, configured to locate a first position of a clutter scatterer and a tag based on the clutter tag reflectivity, and identify the tag from the first position using the tag antenna reflectivity;

[0036] A channel correction module is used to extract and construct a target channel matrix of the tag from the original channel matrix according to the tag antenna reflectivity;

[0037] A bit modulation module is used to perform spatial modulation on the information bits to be transmitted through the transmitting array, generate constellation symbols and determine the active tag from each tag;

[0038] The communication decoding module is used to adopt a transmitting array to backscatter the constellation symbol through the activated tag to a receiving array, and demodulate and decode the received signal of the constellation symbol and the target channel matrix through the receiving array to output information bits.

[0039] A third aspect of the present invention provides a computer device comprising a memory and a processor, wherein a computer program is stored in the memory. When the computer program is executed by the processor, the processor executes the steps of the synchronous perception and backscatter communication method based on spatial modulation and backscattering as described in any one of the above items.

[0040] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed, implements the synchronous sensing and backscattering communication method based on spatial modulation and inverse scattering as described in any one of the above items.

[0041] A fifth aspect of the present invention provides a computer program product, comprising a computer program / instruction, which, when executed by a processor, implements the synchronous perception and backscattering communication method based on spatial modulation and inverse scattering as described in any one of the above items.

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

[0043] The above-mentioned solution of the present invention provides a synchronous sensing and backscattering communication method based on spatial modulation and backscattering, comprising: after transmitting a pilot signal to a tag through a transmitting array, modulating the load impedance of the tag to generate multiple modulated pilot signals of the pilot signal and backscattering them to a receiving array; using the receiving array to determine the clutter tag reflectivity and the tag antenna reflectivity based on the received voltage generated corresponding to each modulated pilot signal and the original channel matrix of the area of ​​interest; locating the first position of the clutter scatterer and the tag based on the clutter tag reflectivity, and identifying the tag from the first position using the tag antenna reflectivity; extracting and constructing the target channel matrix of the tag from the original channel matrix according to the tag antenna reflectivity; spatially modulating the information bits to be transmitted through the transmitting array to generate constellation symbols, and determining the active tag from each tag; using the transmitting array to backscatter the constellation symbols through the activated tags to the receiving array, and demodulating and decoding the information bits through the receiving array based on the received signal of the constellation symbols and the target channel matrix. Based on the above-mentioned solution, the backscattering tags are accurately located and identified in a cluttered environment by dynamically modulating the tag state, and spatial modulation is integrated into the backscattering communication to achieve high spectrum efficiency and low power consumption backscattering communication, thereby improving the reliability of the backscattering communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 A flowchart of a synchronous sensing and backscattering communication method based on spatial modulation and backscattering provided by an embodiment of the present invention;

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

[0047] Figure 3 A schematic diagram of the positioning and identification results of four tags and a nearby clutter scatterer provided in an embodiment of the present invention;

[0048] Figure 4 Schematic diagram comparing the BER performance of SM, V-BLAST, and SIMO at spectral efficiencies of 3 bits / s / Hz and 4 bits / s / Hz provided by an embodiment of the present invention;

[0049] Figure 5Schematic diagram comparing the BER performance of QSM and SM at spectrum efficiencies of 4 bits / s / Hz, 6 bits / s / Hz, and 7 bits / s / Hz provided in an embodiment of the present invention;

[0050] Figure 6 A structural block diagram of a synchronous sensing and backscattering communication device based on spatial modulation and backscattering provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The embodiments of the present invention provide a method and apparatus for synchronous sensing and backscattering communication based on spatial modulation and inverse scattering, which is used to solve the technical problem that the positioning and identification accuracy of backscattering tags in the existing ISAC framework is low, resulting in low reliability of backscattering communication.

[0052] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0053] See also Figure 1 , Figure 1 A flowchart of the steps of a synchronous sensing and backscattering communication method based on spatial modulation and backscattering provided by an embodiment of the present invention.

[0054] This embodiment provides a synchronous sensing and backscattering communication method based on spatial modulation and backscattering, which is applied to Figure 2 The integrated sensing and backscatter communication system shown is a bistatic system comprising a transmitting array, a receiving array and a region of interest (DOI); the transmitting array and the receiving array outside the region of interest are configured as an independent uniform linear array (ULA). The transmitting antenna (TransmitArray) and the receiving array are respectively composed of Receive Array; The DOI represents the cross section of a two-dimensional plane containing a clutter scatterer and a tag. The size of the DOI is , is the x-direction dimension, is the y-dimension, which includes clutter scatterers with fixed reflection coefficients and tags that can perform backscattering communication by dynamically modulating their reflection coefficients. For ease of analysis, DOI is discretized into A uniform grid structure composed of grid cells, where , , is the number of grid cells in the x direction, is the unit length of the grid cell in the x direction, is the number of grid cells in the y direction, is the unit length of the grid unit in the y direction, and the area covered by each grid unit is , the total number of grid cells is , the index of each grid cell is ; Methods include:

[0055] Step 101: After transmitting a pilot signal to a tag through a transmitting array, the load impedance of the tag is modulated to generate a plurality of modulated pilot signals of the pilot signal and backscatter them to a receiving array.

[0056] In a specific implementation of this embodiment, the modulated pilot signal includes an open-circuit pilot signal and a short-circuit pilot signal, and step 101 includes the following sub-steps:

[0057] S11, transmitting a pilot signal to the tag through the transmitting antenna;

[0058] S12, modulating the load impedance of the tag to be in an open circuit state, and generating an open circuit pilot signal corresponding to the received pilot signal through the tag;

[0059] S13, after the load impedance of the modulation tag is in a short-circuit state, generating a short-circuit pilot signal corresponding to the received pilot signal through the tag;

[0060] S14. Backscatter the open-circuit pilot signal and the short-circuit pilot signal to a receiving array.

[0061] It should be noted that this embodiment should be able to accurately locate and identify a single tag or a combination of multiple tags in a complex environment containing clutter scatterers in order to facilitate data communication. In the proposed system, The transmitting antenna is located at The incident electric field is generated at and propagates toward the clutter scatterers and tags within the DOI. The interaction between the incident electric field and the target will produce the first The transmitting antenna is located at The scattered electric field at , the scattered electric field carries information about the electromagnetic properties of the target. According to the Lippmann-Schwinger (LS) formula, The transmitting antenna is located at The total electric field at is described as the superposition of the incident and scattered components as follows:

[0062] (1)

[0063] in The total field can be expressed as:

[0064] (2)

[0065] Where, For location The reflectivity of clutter scatterers and tags at ;

[0066] In fact, direct measurement of the scattered fields in (1) and (2) is unrealistic. Instead, the scattered signal will be captured by the receiving antenna and converted into a corresponding measurable voltage. The scattered field generated by the transmitting antenna is The receiving voltage of the receiving antenna for:

[0067] (3)

[0068] Where, To encourage the unit The incident field radiated by the receiving antenna, is the normalization factor, is the imaginary unit, is the angular frequency, is the vacuum permeability, For the region of interest, is the area covered by the grid cells in the region of interest; since and are unknown and are recovered directly from the measured voltage This will lead to nonlinear and ill-posed inverse problems. To simplify this inverse scattering problem, we apply the Born approximation (BA) and approximate the total field with the incident electric field, that is, , so formula (3) is simplified to:

[0069] (4)

[0070] All from transmit antennas and Voltage measurement of the receiving antenna Collect a single received voltage column vector , then the forward scattering process can be compactly expressed as a linear equation as follows:

[0071] (5)

[0072] Where, is the vectorized reflectivity distribution, whose elements The reflectivity of each grid cell position within the DOI, is the original channel matrix;

[0073] Original channel matrix It can effectively describe the sensing and communication propagation channel connecting the transmitting array and the receiving array, which is organized as , where the channel vector Each element of is defined as follows:

[0074] (6)

[0075] Since the incident electric field can be simulated using electromagnetic simulation software, in one implementation, the process of determining the original channel matrix includes: performing electromagnetic simulation on the region of interest, determining the incident electric field of the transmitting array and the receiving array at each position in the region of interest, calculating the corresponding channel vector using the incident electric field at each position, and synthesizing the channel vectors to form the original channel matrix;

[0076] Since the tag in backscattering usually includes an antenna, the tag's antenna has a fixed impedance and a load impedance that can be dynamically modulated , by changing , the tag can modulate the reflection coefficient , thereby encoding data into the amplitude and phase of the reflected RF signal, the reflection coefficient Defined as:

[0077] (7)

[0078] Where, is the complex conjugate operation;

[0079] In the aforementioned scenario, DOI includes clutter scatterers and backscatter tags, so the The transmitting antenna is located at The resulting scattered electric field can be decomposed into two different components:

[0080] (8)

[0081] Where, is the scattered field from the clutter scatterer, is the scattered field from the tag;

[0082] When When the root antenna illuminates the tag, the scattered electric field generated by the tag can be further divided into structural mode and antenna mode components, as shown below:

[0083] (9)

[0084] in, is the scattered field of the tag structure mode, which is independent of the load impedance; is the scattered field of the tag antenna pattern, which depends on the load impedance; is under matched load conditions (i.e. The induced current at the tag antenna when is the field radiated by the tag antenna under unit excitation; since clutter scattering and tag structural mode scattering are invariant with respect to the load impedance, these two impedance-independent terms are combined into a unified scattered field component , which can be called the clutter tag scattering field:

[0085] (10)

[0086] Therefore, using Equations (7), (9) and (10), the scattered field described in Equation (8) can be concisely expressed as:

[0087] (11)

[0088] Similarly, the reflectivity distribution of Equation (5) It can be divided into components that are independent of the load impedance and components that are related to the load impedance, as follows:

[0089] (12)

[0090] Where, The reflectivity related to the structure pattern of clutter scatterers and tags can be called clutter tag reflectivity, which helps to locate clutter scatterers and tags; The reflectivity corresponding to the tag antenna pattern can be called the tag antenna reflectivity, which is helpful for tag identification. Using equations (1)-(6) and (12), the voltage It can be further broken down into:

[0091] (13)

[0092] Where, The received voltage component related to the clutter scatterer and tag structure mode can be called the clutter tag voltage component, and it is related to Related, Organized as , where each clutter label voltage sub-vector ;akin, is the received voltage component corresponding only to the scattering of the tag antenna pattern, which is related to Related, it is organized as , where each tag antenna voltage subvector ;in, and Indicates the The voltage components received by the receiving antennas are all from the The scattering field generated by the transmitting antenna is related to the structural mode of the clutter scatterer and the tag, while the latter corresponds to the antenna mode scattering of the tag. The spatial distribution of can locate clutter scatterers and tags, and It provides important information for distinguishing and identifying tags in a clutter environment;

[0093] Since the receiving array directly measures the voltage vector , so extract each voltage component and An indirect method is required, which involves controlling the reflection coefficient To simplify this process, the load impedance of the tag Modulates between open-circuit and short-circuit conditions, resulting in two corresponding reflection coefficient states and , as defined in Equation (7), this modulation method effectively implements binary phase shift keying (BPSK), which allows the voltage components to be separated. The tag transmits these two modulated pilot signals through backscatter communication. and ;

[0094] Based on the above principles, in order to realize the positioning and identification of the expression, a pilot signal is first transmitted to the tag through the transmitting array. The pilot signal can be understood as a known reference signal. For details, please refer to the prior art. When the tag receives the pilot signal, the load impedance of the tag is modulated so that the tag is in different modulation states and thus presents different reflection coefficient states. Such different reflection coefficients can be referred to as modulated pilot signals in this embodiment, and then are all backscattered to the receiving array so that a corresponding receiving voltage is generated at the receiving array; in a specific implementation method, when BPSK modulation is specifically applied, such modulation state can include an open circuit state and a short circuit state, and the modulated pilot signal includes an open circuit pilot signal and a short circuit pilot signal, so an open circuit pilot signal is generated by modulation in the open circuit state. , modulate and generate short-circuit pilot signal in short-circuit state .

[0095] It is worth noting that, in order to simplify the analysis, this embodiment adopts a basic two-state modulation scheme, that is, modulating the tag between the open-circuit and short-circuit states to implement BPSK modulation. Nevertheless, the proposed system is highly adaptable and can easily support other modulation formats by changing the reflection coefficient by appropriately adjusting the load impedance of the tag. For example, by adjusting the load impedance to match the required complex reflection coefficient, higher-order modulation schemes such as 4-QAM, 8-QAM, and 16-QAM can be implemented.

[0096] Step 102: Using a receiving array, based on the received voltages generated corresponding to the received modulated pilot signals and the original channel matrix of the region of interest, determine the clutter tag reflectivity and the tag antenna reflectivity.

[0097] It should be noted that after receiving the modulated pilot signal, the receiving array generates a corresponding receiving voltage. Since the original channel matrix of the region of interest describes the perception and communication propagation channel connecting the transmitting array and the receiving array, this embodiment determines the clutter tag reflectivity and tag antenna reflectivity that can be used to locate and identify clutter scatterers and tags based on the receiving voltage and the original channel matrix.

[0098] In a specific implementation of this embodiment, step 102 includes the following sub-steps:

[0099] S21 , measuring an open-circuit receiving voltage of a receiving array when receiving an open-circuit pilot signal and a short-circuit receiving voltage of a receiving array when receiving a short-circuit pilot signal.

[0100] It should be noted that, in this embodiment, the modulated pilot signal includes an open-circuit pilot signal and a short-circuit pilot signal. According to equation (13), the received voltage vector measured under these conditions can be expressed as:

[0101] (14)

[0102] (15)

[0103] Where, For open circuit receiving voltage, Receive voltage for short circuit.

[0104] S22. Determine the clutter tag voltage component and the tag antenna voltage component using the open-circuit receiving voltage and the short-circuit receiving voltage.

[0105] In a more specific implementation of this embodiment, sub-step S22 includes:

[0106] Perform an average operation on the sum of the open-circuit receiving voltage and the short-circuit receiving voltage to determine the clutter tag voltage component;

[0107] Perform an average operation on the difference between the open-circuit receiving voltage and the short-circuit receiving voltage, and output the tag antenna voltage component.

[0108] It should be noted that the required voltage component can be recovered based on the open circuit receiving voltage and the short circuit receiving voltage by the following linear combination: and :

[0109] (16)

[0110] (17)

[0111] S23. According to the compressed sensing algorithm and the two-step iterative shrinkage threshold algorithm, the clutter tag reflectivity is solved based on the clutter tag voltage component and the original channel matrix of the region of interest.

[0112] It should be noted that, in the positioning stage, this embodiment should be based on reconstruction To determine the location of clutter scatterers and tags, according to equations (5), (12)-(13), and The linear relationship between them is expressed as:

[0113] (18)

[0114] Given that clutter scatterers are sparsely distributed in the DOI, the reflectivity vector It is also sparse in itself. In addition, since the total number of measurements Typically less than the number of unknown reflectance elements , so the reconstruction problem in equation (18) is underdetermined and belongs to an ill-posed problem. To solve this problem, this embodiment adopts compressed sensing (CS) technology and expresses the reconstruction process as Norm minimization problem:

[0115] (19)

[0116] Where, express norm; To effectively solve this optimization problem, this embodiment adopts a two-step iterative shrinkage threshold (TwIST) algorithm for iterative solution. The algorithm combines iterative nonlinear shrinkage steps and adaptive parameter selection, making it particularly effective for sparse signal reconstruction in perception applications.

[0117] S24. Using a compressed sensing algorithm and a two-step iterative shrinkage threshold algorithm, the output tag antenna reflectivity is solved based on the tag antenna voltage component and the original channel matrix.

[0118] It should be noted that, in the identification phase, a method similar to that in sub-step S23 is used to determine the received voltage. reconstruction , so as to achieve accurate label recognition, based on equations (5), (12)-(13), we can also recover Expressed as Norm minimization problem:

[0119] (20)

[0120] (twenty one)

[0121] This optimization problem can also be solved by the TwIST algorithm, since represents the reflectivity distribution associated with the tag antenna pattern, so its reconstruction enables accurate tag identification.

[0122] This embodiment uses sparse reconstruction and inverse scattering technology to improve perception accuracy. After being processed by the compressed sensing (CS) algorithm, the structural pattern component can accurately locate clutter scatterers and tags, while the antenna pattern component supports accurate identification of single and multiple tags.

[0123] Step 103: locate the first position of the clutter scatterer and the tag based on the clutter tag reflectivity, and identify the tag from the first position using the tag antenna reflectivity.

[0124] It should be noted that first, based on the clutter tag reflectivity, the first position where the tag or clutter scatterer may exist in the area of ​​interest is located, and then the tag location is identified from the first position through the tag antenna reflectivity. The global environment perception and local tag specificity recognition are used to accurately perceive and reconstruct the tag.

[0125] Step 104: Extract and construct a target channel matrix for the tag from the original channel matrix according to the tag antenna reflectivity.

[0126] It should be noted that the location of the tag can be determined based on the tag antenna reflectivity. For example, the tag antenna reflectivity is a column vector composed of "1" and "0", where each "1" corresponds to a tag, and the number of "1" is equal to the total number of tags. , each "1" position in the column vector corresponds to the position of a label in the DOI area, for example:

[0127]

[0128] As can be seen from the above vector, at this time , since the first "1" is the first element of the vector, the position of the first label is the first grid unit, and the second "1" is the third element of the vector, the position of the second label is the third grid unit;

[0129] Original channel matrix Each column vector of corresponds to the channel vector from the position of each grid unit in the DOI area to the receiving array, and the tag antenna reflectivity determines which grid unit each tag is at. Therefore, the channel vector corresponding to the grid unit where each tag is located can be obtained from the original channel matrix Extract them and combine these extracted channel vectors into a modified channel matrix , which is called the target channel matrix; since some grid cells of DOI have clutter scatterers, and clutter scatterers will cause interference, the modified channel matrix The channel vector that does not contain the location of the clutter scatterer, that is, it has removed the interference of the clutter scatterer, can improve the performance of backscatter communication.

[0130] Step 105: spatially modulate the information bits to be transmitted through the transmitting array to generate constellation symbols and determine the active tag from among the tags.

[0131] It should be noted that, in this embodiment, after completing the positioning and identification procedures based on the pilot signal, each tag starts backscattering data transmission. Specifically, each tag uses a radio frequency switch to dynamically select a different load impedance. , thereby adjusting the reflection coefficient To achieve These different reflection coefficient states directly correspond to the binary constellation symbol; backscatter communication system in a single tag ( ) scenario as a single-input multiple-output (SIMO) system, and in multi-label ( ) scenario, it operates as a multiple-input multiple-output (MIMO) system. To comprehensively handle general situations, expand application scenarios, and adapt to more modulation technologies, this embodiment focuses on the multi-label MIMO backscatter communication scenario to further improve spectrum efficiency and data rate.

[0132] In a multi-tag environment, spatial modulation schemes such as SM and QSM are widely adopted. Among them, spatial modulation (SM) activates only one antenna at a time for data transmission, eliminating inter-channel interference (ICI) and inter-antenna synchronization (IAS) requirements, and improving bit error rate (BER) performance. In addition, it improves spectrum efficiency by encoding additional bits into the antenna index. Advanced spatial modulation schemes, such as quadrature spatial modulation (QSM), activate two antennas simultaneously to independently transmit the real part and imaginary part of a complex constellation symbol. Since the real part and imaginary part of this constellation symbol are modulated to the corresponding real part and imaginary part of the carrier signal, respectively. In the imaginary part, QSM maintains the orthogonality between the transmitted information to prevent inter-channel interference; the total bits transmitted by SM and QSM are composed of two parts: the bits of the constellation symbol and the bits of the label index. The similarity between SM and QSM is that only one constellation symbol is transmitted each time. The difference is that SM only transmits additional information bits through one label index each time, while QSM transmits additional information bits through two label indexes each time. Therefore, QSM can transmit more information bits and achieve higher spectrum efficiency than SM. In specific implementation, at the transmitting end, the information bits to be sent are first divided into two parts. One part of the bits is modulated and mapped into The other part of the bits is mapped into the index of the tag to select the tag and thus determine the activated tag, which is used to transmit the M-ary constellation symbol.

[0133] Step 106: Use the transmitting array to backscatter the constellation symbol through the activated tag to the receiving array, and the receiving array demodulates and decodes the received signal of the constellation symbol and the target channel matrix to output information bits.

[0134] It should be noted that, assuming the average transmit power is normalized to 1, there are tags, using the channel state information (CSI) obtained from the antenna pattern in the positioning and identification stages, and Remove the voltage components of clutter scatterers and structural modes , then the backscattered signal received after each symbol is transmitted, that is, the received signal, can be expressed as:

[0135] (twenty two)

[0136] Where, For the tags, , For the The constellation symbol transmitted by each tag, is additive Gaussian white noise;

[0137] By getting the original channel matrix The target channel matrix has been extracted and determined , while in the multi-tag MIMO communication scenario, the symbols sent by all tags constitute the signal vector ,satisfy ,in is the conjugate transpose, is the expectation, then (22) can be simplified to:

[0138] (twenty three)

[0139] The received signal represented by equation (23) is demodulated, such as by performing maximum likelihood (ML) detection, traversing all possible constellation symbols and activation labels, estimating the index of the transmitted constellation symbol and activation label, and decoding and mapping the demodulation result into the original information bits.

[0140] For example, when SM modulation is adopted: the SM scheme not only The information bits are encoded by binary constellation symbols and are also encoded by the index of the transmission label. Its spectrum efficiency is ,forward Bit modulation Base constellation symbol ,back Bit determines the active tag index , so the transmission vector of SM Expressed as:

[0141] (twenty four)

[0142] in, and , To activate the tag index, is the constellation symbol, the received signal vector in the SM scheme is It is given by:

[0143] (25)

[0144] Where, yes No. At the receiver, maximum likelihood (ML) detection estimates the transmitted information by solving the following problem:

[0145] (26)

[0146] in, ;

[0147] When QSM modulation is used: The QSM scheme uses two different tags to independently transmit a complex constellation symbol The real and imaginary parts of the signal are modulated onto the corresponding real and imaginary parts of the carrier signal. This method can improve the spectrum efficiency to , while maintaining orthogonality between transmitted information to prevent ICI; specifically, the first part Bits determine constellation symbols , Part 2 Bit mapping to tag index , to transmit the real part , construct the vector , the last part Bit mapping to tag index , to transmit the real part , thus obtaining the vector , so the transmitted signal vector is , accordingly, the received signal of QSM is:

[0148] (27)

[0149] Where, and They are No. and List, and , the best ML detection of QSM is as follows:

[0150] (28)

[0151] in ;

[0152] After constructing the signal vector in the modulation stage, in the demodulation stage, all possible constellation symbols and activation labels are traversed through the maximum likelihood detection described by equation (26) or (28) to construct all possible vectors (or ), then find (or ) and the received signal vector (or ), find the vector corresponding to the smallest Euclidean distance (or ), the transmitted constellation symbol and the index of the activated tag can be estimated to complete the demodulation.

[0153] To further illustrate the backscatter communication performance of this embodiment, an experimental verification was conducted:

[0154] A. System Configuration:

[0155] The proposed system operates at a frequency of 2.4 GHz, corresponding to a wavelength of , DOI span is , and is discretized into grid cells, each grid cell measures , so we need to estimate unknown parameters; both the transmit and receive arrays are implemented as uniform linear arrays (ULA), each consisting of The patch antenna grid is composed of

[0156] B. Positioning and recognition performance:

[0157] In order to quantitatively evaluate the quality of perception performance, the peak signal-to-noise ratio (PSNR) is used as a performance indicator. The higher the PSNR value, the better the image reconstruction effect. In the reconstructed image, the white rectangular box indicates the actual position of the tag, while the green box indicates the actual position of the clutter scatterer. The tags are modeled as copper dipole antennas, and the radius of each antenna is , the height is .

[0158] Figure 3 We present perception results in a multi-tag scenario where four tags are placed together with copper clutter scatterers of different sizes; Figure 3 (a) shows that the system accurately reconstructs the positions of all four tags and the clutter scatterer, and then selects the tag containing subset of labels and evaluate all possible combinations, a total of Configuration Figure 3 The results shown in (b)-(e) )、 Figure 3 The results shown in (f)-(k) )、 Figure 3 The results shown in (l)-(n) )and Figure 3 The results shown in (o) ) clearly demonstrates that the proposed system consistently and accurately identifies and localizes each label in all tested combinations; The corresponding reconstructed PSNR values ​​are (a) PSNR=18.96dB, (b) PSNR=24.88dB, (c) PSNR=26.05dB, (d) PSNR=25.80dB, (e) PSNR=26.77dB, (f) PSNR=22.91dB, (g) PSNR=23.06dB, (h) PSNR=23.77dB, (i) PSNR=22.45dB, (j) PSNR=23.43dB, (k) PSNR=23.14dB, (l) PSNR=21.34dB, (m) PSNR=21.28dB, (n) PSNR=21.35dB and (o) PSNR=20.03dB; these results confirm the robustness and reliability of the system in scenarios involving multiple labels.

[0159] C. Backscatter Communication Performance

[0160] Figure 4 Simulation results are presented to evaluate the communication performance of the proposed backscatter communication system employing SM and QSM and compared with V-BLAST and SIMO schemes. These performance analyses are performed using the channel characteristics obtained through antenna pattern measurements.

[0161] In the V-BLAST scheme, all available tags send independent symbols simultaneously to achieve spectrum efficiency , in the receiving array, the minimum mean square error (MMSE) estimation is used to detect the transmitted symbols as follows:

[0162] (29)

[0163] Where, is the signal vector estimated by V-BLAST, is the variance of the noise, The dimension is The identity matrix, is the received signal of V-BLAST;

[0164] Figure 4 The BER performance of SM was compared with that of the Vertical Clock Laboratory Layered Space-Time (V-BLAST) and SIMO schemes at spectrum efficiencies of 3 and 4 bits / hertz / second (bits / s / Hz). The results show that SM has better BER performance than V-BLAST and SIMO, and this performance advantage becomes more obvious at higher signal-to-noise ratio (SNR) values. At 0.05 Mbps, SM achieves approximately 2dB and 5dB performance gains compared to V-BLAST and SIMO, respectively. At 4 bits / s / Hz, SM's advantage increases further, achieving more than 2dB performance gain compared to V-BLAST and approximately 6dB performance gain compared to SIMO. These results clearly show that SM's advantage grows with increasing spectral efficiency.

[0165] Figure 4 The performance comparison between SM and QSM at spectral efficiencies of 4 bits / s / Hz, 6 bits / s / Hz, and 7 bits / s / Hz in the backscatter communication framework is further illustrated; However, at higher spectral efficiencies of 6 bits / s / Hz and 7 bits / s / Hz, this trend is reversed, with QSM outperforming SM by approximately 5 dB and 2.5 dB, respectively.

[0166] In the embodiments of the present invention, compared with existing perception system research, such as orthogonal coded active illumination imaging, two-sided reflection imaging, millimeter wave imaging and perception systems based on Fourier algorithms, most of them rely on a wider frequency band and require the deployment of a large number of antennas, which not only greatly increases the hardware cost and system complexity, but also makes it difficult to adapt to the 6G era where spectrum resources are becoming increasingly scarce. In addition, the perception systems that have previously used inverse scattering technology are limited to sensing objects that are limited to clutter scatterers and cannot provide accurate positioning for tags in backscatter communication systems. More importantly, the above-mentioned various perception systems usually focus on improving perception performance and lack the integration of communication functions, and cannot be effectively applied in the ISAC framework. For the above-mentioned research, In order to overcome the limitations of the research, the method proposed in this embodiment seamlessly combines the perception of the inverse scattering method with the backscattering communication using SM and QSM technologies for spatial modulation. By dynamically modulating the tag state, the structural mode component and the antenna mode component can be effectively separated, thereby facilitating the accurate extraction of scattering characteristics, accurately locating and identifying backscattering tags in cluttered environments, and integrating spatial modulation into backscattering communication to further improve the performance in multi-antenna scenarios, thereby completing backscattering communication with high spectrum efficiency and low power consumption, and maintaining robust performance even when the array and available spectrum resources are limited. By using compressed sensing-assisted inverse scattering positioning, the hardware complexity is reduced and spectrum congestion is alleviated.

[0167] See also Figure 6 , Figure 6 A structural block diagram of a synchronous sensing and backscattering communication device based on spatial modulation and backscattering provided by an embodiment of the present invention.

[0168] The present invention provides a synchronous sensing and backscattering communication device based on spatial modulation and backscattering, involving a transmitting array, a receiving array, and a region of interest, wherein the region of interest contains clutter scatterers and tags; the device includes:

[0169] The pilot scattering module 601 is used to transmit a pilot signal to the tag through the transmitting array, modulate the load impedance of the tag to generate multiple modulated pilot signals of the pilot signal, and scatter them back to the receiving array;

[0170] A reflectivity determination module 602 is configured to determine a clutter tag reflectivity and a tag antenna reflectivity using a receiving voltage generated by a receiving array based on each received modulated pilot signal and an original channel matrix of the region of interest;

[0171] a tag sensing module 603 for locating a first position of a clutter scatterer and a tag based on a clutter tag reflectivity, and identifying the tag from the first position using a tag antenna reflectivity;

[0172] The channel correction module 604 is used to extract and construct the target channel matrix of the tag from the original channel matrix according to the tag antenna reflectivity;

[0173] A bit modulation module 605 is configured to perform spatial modulation on the information bits to be transmitted through a transmitting array, generate constellation symbols, and determine an active tag from each tag;

[0174] The communication decoding module 606 is configured to use the transmitting array to backscatter the constellation symbols through the activated tags to the receiving array, and to demodulate and decode the received signals of the constellation symbols and the target channel matrix to output information bits through the receiving array.

[0175] Furthermore, the modulated pilot signal includes an open-circuit pilot signal and a short-circuit pilot signal; the pilot scattering module 601 is specifically configured to:

[0176] Transmitting a pilot signal to the tag via a transmitting antenna;

[0177] The load impedance of the modulation tag is in an open circuit state, and an open circuit pilot signal corresponding to the received pilot signal is generated by the tag;

[0178] After the load impedance of the modulation tag is in a short-circuit state, a short-circuit pilot signal corresponding to the received pilot signal is generated by the tag;

[0179] The open-circuit pilot signal and the short-circuit pilot signal are backscattered to the receiving array.

[0180] Furthermore, the reflectivity determination module 602 is specifically configured to:

[0181] measuring an open-circuit receiving voltage of the receiving array when it receives an open-circuit pilot signal and a short-circuit receiving voltage of the receiving array when it receives a short-circuit pilot signal;

[0182] The open circuit receiving voltage and the short circuit receiving voltage are used to determine the voltage component of the clutter tag and the voltage component of the tag antenna;

[0183] According to the compressed sensing algorithm and the two-step iterative shrinkage threshold algorithm, the output clutter tag reflectivity is solved based on the clutter tag voltage component and the original channel matrix of the region of interest;

[0184] The output tag antenna reflectivity is solved based on the tag antenna voltage component and the original channel matrix through the compressed sensing algorithm and the two-step iterative shrinkage threshold algorithm.

[0185] Furthermore, the process of determining the original channel matrix includes:

[0186] Perform electromagnetic simulation on the region of interest to determine the incident electric field of the transmitting array and the receiving array at each position in the region of interest;

[0187] The incident electric field at each position is used to calculate the corresponding channel vector, and the channel vectors are combined to form the original channel matrix.

[0188] Furthermore, the open circuit receiving voltage and the short circuit receiving voltage are used to determine the clutter tag voltage component and the tag antenna voltage component, including:

[0189] Perform an average operation on the sum of the open-circuit receiving voltage and the short-circuit receiving voltage to determine the clutter tag voltage component;

[0190] Perform an average operation on the difference between the open-circuit receiving voltage and the short-circuit receiving voltage, and output the tag antenna voltage component.

[0191] Furthermore, receiving a signal specifically includes:

[0192] ;

[0193] in, , ;

[0194] Where, To receive the signal, is the target channel matrix, is the transmission vector of the activation tag based on the constellation symbol, is additive white Gaussian noise, For the tags, For the The constellation symbol transmitted by each tag, is the total number of labels, For expectations, is the conjugate transpose.

[0195] An embodiment of the present invention also provides a computer device, including a memory and a processor, wherein a computer program is stored in the memory; when the computer program is executed by the processor, the processor executes the steps of the synchronous perception and backscattering communication method based on spatial modulation and backscattering as in any of the above embodiments.

[0196] An embodiment of the present invention also provides a computer-readable storage medium having a computer program / instruction stored thereon. When the computer program / instruction is executed by a processor, the steps of the synchronous perception and backscattering communication method based on spatial modulation and backscattering as in any of the above embodiments are implemented.

[0197] An embodiment of the present invention also provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the synchronous sensing and backscattering communication method based on spatial modulation and backscattering as in any of the above embodiments.

[0198] Those skilled in the art will 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 aforementioned method embodiments and will not be repeated here.

[0199] In the several embodiments provided in this 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 schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as 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 mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0200] The units described as separate components may or may not be physically separate, and 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 these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0201] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0202] 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, or the portion 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 for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0203] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A synchronous sensing and backscattering communication method based on spatial modulation and backscattering, characterized in that: The invention relates to a transmitting array, a receiving array and a region of interest, wherein the region of interest contains clutter scatterers and tags; the method includes: After transmitting the pilot signal to the tag through the transmitting array, modulating the load impedance of the tag to generate multiple modulated pilot signals of the pilot signal and backscattering them to the receiving array; The clutter tag reflectivity and the tag antenna reflectivity are determined by using a receiving array based on the received voltage generated corresponding to each received modulated pilot signal and the original channel matrix of the region of interest; Locating a first position of a clutter scatterer and a tag based on the clutter tag reflectivity, and identifying the tag from the first position using the tag antenna reflectivity; Extracting and constructing a target channel matrix of the tag from the original channel matrix according to the tag antenna reflectivity; The information bits to be transmitted are spatially modulated by the transmitting array to generate constellation symbols and determine the active tag from each tag; The constellation symbol is backscattered to a receiving array through an activated tag by a transmitting array, and the receiving array demodulates and decodes the received signal of the constellation symbol and the target channel matrix to output information bits.

2. The synchronous sensing and backscattering communication method based on spatial modulation and inverse scattering according to claim 1, characterized in that: The modulated pilot signal includes an open-circuit pilot signal and a short-circuit pilot signal; after transmitting the pilot signal to the tag through the transmitting array, modulating the load impedance of the tag to generate multiple modulated pilot signals of the pilot signal and backscattering them to the receiving array, including: Transmitting a pilot signal to the tag via a transmitting antenna; The load impedance of the modulation tag is in an open circuit state, and an open circuit pilot signal corresponding to the received pilot signal is generated by the tag; After the load impedance of the modulation tag is in a short-circuit state, a short-circuit pilot signal corresponding to the received pilot signal is generated by the tag; The open-circuit pilot signal and the short-circuit pilot signal are backscattered to a receiving array.

3. The synchronous sensing and backscattering communication method based on spatial modulation and inverse scattering according to claim 2, characterized in that: The method of using the receiving array to determine the clutter tag reflectivity and the tag antenna reflectivity based on the received voltage generated corresponding to each received modulated pilot signal and the original channel matrix of the region of interest includes: measuring an open-circuit receiving voltage of the receiving array when it receives an open-circuit pilot signal and a short-circuit receiving voltage of the receiving array when it receives a short-circuit pilot signal; Determining a clutter tag voltage component and a tag antenna voltage component using the open-circuit receiving voltage and the short-circuit receiving voltage; According to the compressed sensing algorithm and the two-step iterative shrinkage threshold algorithm, the output clutter tag reflectivity is solved based on the clutter tag voltage component and the original channel matrix of the region of interest; The output tag antenna reflectivity is solved based on the tag antenna voltage component and the original channel matrix through a compressed sensing algorithm and a two-step iterative shrinkage threshold algorithm.

4. The synchronous sensing and backscattering communication method based on spatial modulation and inverse scattering according to claim 1, characterized in that: The process of determining the original channel matrix includes: Perform electromagnetic simulation on the region of interest to determine the incident electric field of the transmitting array and the receiving array at each position in the region of interest; The incident electric field at each position is used to calculate the corresponding channel vector, and the channel vectors are combined to form an original channel matrix.

5. The synchronous sensing and backscattering communication method based on spatial modulation and inverse scattering according to claim 3, characterized in that: The determining of the clutter tag voltage component and the tag antenna voltage component by using the open-circuit receiving voltage and the short-circuit receiving voltage includes: Performing a mean operation on the sum of the open-circuit receiving voltage and the short-circuit receiving voltage to determine a clutter tag voltage component; Performing a mean operation on the difference between the open-circuit receiving voltage and the short-circuit receiving voltage, and outputting a tag antenna voltage component.

6. The synchronous sensing and backscattering communication method based on spatial modulation and inverse scattering according to claim 1, characterized in that: The received signal specifically includes: ； in, , ; Where, To receive the signal, is the target channel matrix, is the transmission vector of the activation tag based on the constellation symbol, is additive white Gaussian noise, For the tags, For the The constellation symbol transmitted by each tag, is the total number of labels, For expectations, is the conjugate transpose.

7. A synchronous sensing and backscattering communication device based on spatial modulation and backscattering, characterized in that: The invention relates to a transmitting array, a receiving array and an area of ​​interest, wherein the area of ​​interest contains clutter scatterers and tags; the device includes: A pilot scattering module is used to transmit a pilot signal to the tag through the transmitting array, modulate the load impedance of the tag to generate multiple modulated pilot signals of the pilot signal and scatter them back to the receiving array; A reflectivity determination module is used to determine the clutter tag reflectivity and the tag antenna reflectivity using a receiving voltage generated by the receiving array based on each received modulated pilot signal and an original channel matrix of the region of interest; a tag sensing module, configured to locate a first position of a clutter scatterer and a tag based on the clutter tag reflectivity, and identify the tag from the first position using the tag antenna reflectivity; A channel correction module is used to extract and construct a target channel matrix of the tag from the original channel matrix according to the tag antenna reflectivity; A bit modulation module is used to perform spatial modulation on the information bits to be transmitted through the transmitting array, generate constellation symbols and determine the active tag from each tag; The communication decoding module is used to adopt a transmitting array to backscatter the constellation symbol through the activated tag to a receiving array, and demodulate and decode the received signal of the constellation symbol and the target channel matrix through the receiving array to output information bits.

8. A computer device, characterized in that: It includes a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the processor performs the steps of the synchronous perception and backscatter communication method based on spatial modulation and backscattering as described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instructions are executed by a processor, the steps of the synchronous sensing and backscattering communication method based on spatial modulation and inverse scattering are implemented.

10. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the synchronous sensing and backscattering communication method based on spatial modulation and inverse scattering are implemented.

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