A method and apparatus for simultaneous sensing and backscatter communication based on spatial modulation and inverse scattering

Abstract

The application discloses a kind of based on space modulation and reverse scattering's synchronous sensing and reverse scattering communication method and device, it is related to communication technical field, including: through transmitting array to tag pilot signal and modulate the load impedance of tag again backscatter to receiving array;Using the receiving voltage generated by receiving array and original channel matrix determines clutter tag reflectivity and tag antenna reflectivity;Based on clutter tag reflectivity positioning and identification label;From original channel matrix, according to tag antenna reflectivity, extract and construct the target channel matrix of label;Information bits are spatially modulated by transmitting array, constellation symbol is generated and active label is determined;Using transmitting array, constellation symbol is backscattered to receiving array by active label, and combined with target channel matrix, demodulation and decoding output information bits.In the disorderly environment, reverse scattering label is accurately positioned and identified, and space modulation is integrated into reverse scattering communication, and the reliability of reverse scattering communication is improved.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a backscatter communication method and apparatus based on spatial modulation and backscattering. Background Technology

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

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

[0004] This invention provides a method and apparatus for synchronous sensing and backscatter communication based on spatial modulation and backscattering, which solves the problem of low positioning and identification accuracy of backscatter tags under the existing ISAC framework, resulting in low reliability of backscatter communication.

[0005] The first aspect of this invention provides a synchronous sensing and backscattering communication method 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 method includes:

[0006] After the pilot signal is transmitted to the tag via the transmitting array, the load impedance of the tag is modulated to generate multiple modulated pilot signals of the pilot signal and backscattered to the receiving array.

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

[0008] Based on the clutter tag reflectivity, the first position of the clutter scatterer and the tag is located, and the tag antenna reflectivity is used to identify the tag from the first position;

[0009] The target channel matrix of the tag is constructed by extracting it from the original channel matrix according to the tag antenna reflectivity;

[0010] Spatial modulation of the information bits to be transmitted is performed using the transmission array to generate constellation symbols and determine the active tag from each tag;

[0011] The constellation symbols are backscattered to the receiving array via activation tags using a transmitting array, and the receiving array demodulates and decodes the received signals of the constellation symbols 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; the step of transmitting the pilot signal to the tag via the transmitting array, modulating the tag's load impedance to generate multiple modulated pilot signals of the pilot signal, and backscattering them to the receiving array, includes:

[0013] Transmit pilot signals to the tag via the transmitting antenna;

[0014] The load impedance of the modulation tag is in an open-circuit state, and the tag generates an open-circuit pilot signal corresponding to the received pilot signal.

[0015] When the load impedance of the modulation tag is in a short-circuit state, the tag generates a short-circuit pilot signal corresponding to the received pilot signal.

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

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

[0018] The open-circuit receiving voltage of the receiving array when it receives an open-circuit pilot signal and the short-circuit receiving voltage when it receives a short-circuit pilot signal are measured.

[0019] The clutter tag voltage component and the tag antenna voltage component are determined using the open-circuit received voltage and the short-circuit received voltage;

[0020] Based on the compressed sensing algorithm and the two-step iterative shrinking threshold algorithm, the clutter tag reflectivity is solved by the clutter tag voltage component and the original channel matrix of the region of interest.

[0021] The tag antenna reflectivity is calculated based on the tag antenna voltage component and the original channel matrix using a compressed sensing algorithm and a two-step iterative shrinking threshold algorithm.

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

[0023] Electromagnetic simulation is performed on the region of interest to determine the incident electric fields of the transmitting and receiving arrays at various locations within the region of interest.

[0024] The corresponding channel vector is calculated using the incident electric field at each location, and the original channel matrix is ​​formed by combining the channel vectors.

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

[0026] The sum of the open-circuit received voltage and the short-circuit received voltage is averaged to determine the clutter tag voltage component.

[0027] The difference between the open-circuit received voltage and the short-circuit received voltage is averaged to output the tag antenna voltage component.

[0028] Optionally, the received signal specifically includes:

[0029] ;

[0030] in, , ;

[0031] In the formula, In order to receive signals, For the target channel matrix, To activate the tag's constellation-symbol-based transfer vector, It is additive white Gaussian noise. For the first One tag, For the first The constellation symbol transmitted by the tag, For the total number of tags, As expected, This is the conjugate transpose.

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

[0033] The pilot scattering module is used to modulate the load impedance of the tag to generate multiple modulated pilot signals of the pilot signal after the pilot signal is transmitted to the tag through the transmitting array, and then backscatters the pilot signal to the receiving array.

[0034] The reflectivity determination module is used to determine the reflectivity of clutter tags and tag antennas 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.

[0035] The tag sensing module is used to locate the first position of the clutter scatterer and the tag based on the reflectivity of the clutter tag, and to identify the tag from the first position using the reflectivity of the tag antenna.

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

[0037] The bit modulation module is used to spatially modulate the information bits to be transmitted through the transmission array, generate constellation symbols, and determine the active tag from each tag;

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

[0039] A computer device provided in a third aspect of the present invention includes a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the synchronous sensing and backscattering communication method based on spatial modulation and backscattering as described in any of the preceding claims.

[0040] The fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed, implements the synchronous sensing and backscattering communication method based on spatial modulation and backscattering as described in any of the preceding claims.

[0041] The fifth aspect of the present invention provides a computer program product comprising a computer program / instruction, wherein when the computer program / instruction is executed by a processor, it implements the synchronous sensing and backscattering communication method based on spatial modulation and backscattering as described in any of the preceding claims.

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

[0043] The above-described scheme of the present invention provides a synchronous sensing and backscatter communication method based on spatial modulation and backscattering, comprising: transmitting pilot signals to tags via a transmitting array, modulating the load impedance of the tags to generate multiple modulated pilot signals and backscattering them to a receiving array; using the receiving array to determine the clutter tag reflectivity and tag antenna reflectivity based on the received voltage corresponding to each modulated pilot signal and the original channel matrix of the region 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 via the transmitting array to generate constellation symbols and identifying the active tag from each tag; backscattering the constellation symbols through the active tag to the receiving array via the transmitting array, and demodulating and decoding the received signals of the constellation symbols and the target channel matrix to output the information bits. Based on the above scheme, 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 spectral efficiency and low power consumption backscattering communication, thereby improving the reliability of backscattering communication. Attached Figure Description

[0044] 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.

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

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

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

[0048] Figure 4 A 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 for embodiments of the present invention;

[0049] Figure 5A schematic diagram showing the BER performance comparison between QSM and SM at spectral efficiencies of 4 bits / s / Hz, 6 bits / s / Hz, and 7 bits / s / Hz, provided for embodiments of the present invention;

[0050] Figure 6 This is a structural block diagram of a synchronous sensing and backscattering communication device based on spatial modulation and backscattering, provided in an embodiment of the present invention. Detailed Implementation

[0051] This invention provides a method and apparatus for synchronous sensing and backscatter communication based on spatial modulation and backscattering, which solves the technical problem of low positioning and identification accuracy of backscatter tags under the existing ISAC framework, resulting in low reliability of backscatter communication.

[0052] 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.

[0053] Please see Figure 1 , Figure 1 The flowchart illustrates the steps of a synchronous sensing and backscattering communication method based on spatial modulation and backscattering, as provided in 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, for example... Figure 2 The integrated sensing and backscatter communication system shown is a bistatic system comprising a transmitter array, a receiver array, and a region of interest (DOI). Both the transmitter and receiver arrays, located outside the DOI, are configured as independent uniform linear arrays (ULAs). The transmitter array includes... The transmit array and receiver array are respectively composed of and One receive array; the DOI represents a cross-section of a two-dimensional plane containing a clutter scatterer and a tag, and the DOI has dimensions of [missing information]. , The dimension is in the x-direction. The dimension is in the y-direction, containing a clutter scatterer with a fixed reflection coefficient and a tag capable of backscattering communication by dynamically modulating its reflection coefficient. For ease of analysis, the DOI is discretized into a [database name missing]. A uniform grid structure composed of grid cells, wherein , , The number of mesh cells in the x-direction. The unit length of the grid cell in the x-direction. The number of mesh elements in the y-direction. Let be the unit length of the grid cell in the y-direction, and let be the area covered by each grid cell. The total number of grid cells is The index of each grid cell is The methods include:

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

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

[0057] S11. Transmit pilot signals to the tag via the transmitting antenna;

[0058] S12. The load impedance of the modulation tag is in an open circuit state, and the tag generates an open circuit pilot signal corresponding to the received pilot signal.

[0059] S13. After the load impedance of the modulation tag is in a short-circuit state, the tag generates a short-circuit pilot signal corresponding to the received pilot signal.

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

[0061] It should be noted that this embodiment aims to achieve accurate positioning and identification of single tags or combinations of tags in complex environments containing clutter scatterers, in order to facilitate data communication. In the proposed system, the first... Each transmitting antenna is located at... An incident electric field is generated at the location And propagates to clutter scatterers and tags within the DOI, the interaction between the incident electric field and the target will produce the first Each transmitting antenna is located at... Scattered electric field at the location The scattered electric field carries information about the electromagnetic properties of the target. According to the Lippmann-Schwinger (LS) formula, the first... Each transmitting antenna is located at... Total electric field at the location It is described as the superposition of the incident and scattered components, as shown below:

[0062] (1)

[0063] in This can be represented by the total field as:

[0064] (2)

[0065] In the formula, For position The reflectivity of the clutter scatterer and the tag at the location;

[0066] In fact, directly measuring the scattering fields in (1) and (2) That's impractical. Instead, the scattered signal will be captured by the receiving antenna and converted into a corresponding measurable voltage, due to the... The scattered field generated by the transmitting antenna, in the th... The receiving voltage of each receiving antenna for:

[0067] (3)

[0068] In the formula, Under the incentive of the unit The incident field radiated by a receiving antenna As the normalization factor, The imaginary unit, Angular frequency, The permeability of free space, For region of interest, The area covered by the grid cells in the region of interest; due to the above formula... and Everything is unknown; it can be recovered directly from the measured voltage. This leads to a nonlinear and ill-posed inverse problem. To simplify this inverse scattering problem, we apply the Born approximation (BA), approximating the total field with the incident electric field, i.e., approximating... Therefore, equation (3) simplifies to:

[0069] (4)

[0070] All from One transmitting antenna and Voltage measurements of each receiving antenna Collect a single received voltage column vector In this case, the forward scattering process can be compactly represented by the following linear equation:

[0071] (5)

[0072] In the formula, For vectorized reflectance distribution, its elements The reflectivity corresponding to each grid cell position within the DOI, This is the original channel matrix;

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

[0074] (6)

[0075] Since the incident electric field can be obtained through 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 fields of the transmitting array and the receiving array at each position in the region of interest, calculating the corresponding channel vectors using the incident electric fields at each position, and combining the channel vectors to form the original channel matrix.

[0076] Since tags in backscattering typically include 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 reflectance. This encodes the data into the amplitude and phase of the reflected radio frequency signal, and the reflection coefficient... Defined as:

[0077] (7)

[0078] In the formula, This is a complex conjugate operation;

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

[0080] (8)

[0081] In the formula, The scattered field from the clutter scatterer, The scattered field comes from the tag;

[0082] When the When the 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, The scattered field is the tag structure mode and is independent of the load impedance; The scattered field in tag antenna mode depends on the load impedance; Under the condition of matching load (i.e.) Induced current at the tag antenna (time); This is the field radiated by the tag antenna under unit excitation. Since clutter scattering and tag structure mode scattering are constant relative to the load impedance, these two impedance-independent terms are combined into a unified scattered field component. This can be called the clutter tag scattering field:

[0085] (10)

[0086] Therefore, using equations (7), (9), and (10), the scattering field described in equation (8) can be concisely expressed as:

[0087] (11)

[0088] Similarly, the reflectance 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 detailed below:

[0089] (12)

[0090] In the formula, The reflectivity associated with clutter scatterers and tag structure patterns can be called clutter tag reflectivity, which helps in the localization of clutter scatterers and tags; To specifically correspond to the reflectivity of the tag antenna mode, it can be called the tag antenna reflectivity, which is helpful for tag identification; using equations (1)-(6) and equation (12), voltage It can be further broken down into:

[0091] (13)

[0092] In the formula, The received voltage component related to clutter scatterers and tag structure modes can be called the clutter tag voltage component, and it is related to... Related, Organized as Each clutter tag voltage subvector ;akin, The received voltage component corresponds only to the scattering of the tag antenna mode, and it is related to... Related, it is organized as , where each tag antenna voltage subvector ;in, and Indicates the first The received voltage components received by the first receiving antenna all originate from the second receiving antenna. The scattered fields generated by the transmitting antennas are related to clutter scatterers and the tag's structural mode, while the scattered fields correspond to the tag's antenna mode scattering. Therefore... The spatial distribution can locate clutter scatterers and tags, while This provides important information for distinguishing and identifying tags in cluttered environments;

[0093] Because the receiving array directly measures the voltage vector Therefore, each voltage component is extracted. and An indirect method is required, which involves controlling the reflection coefficient. To simplify this process, the tag's load impedance changes. Modulation is performed between open-circuit and short-circuit conditions, thereby generating two corresponding reflection coefficient states. and As defined in equation (7), this modulation method effectively realizes binary phase shift keying (BPSK), enabling the voltage components to be separated. The tag transmits these two modulated pilot signals via backscatter communication. and ;

[0094] Based on the above principles, to achieve the target location identification, a pilot signal is first transmitted to the tag via a transmitting array. The pilot signal can be understood as a known reference signal, as detailed in existing technologies. When the tag receives the pilot signal, its load impedance is modulated to achieve different modulation states, resulting in different reflection coefficients. These different reflection coefficients, referred to as the modulated pilot signal in this embodiment, are then backscattered to the receiving array, generating a corresponding receiving voltage at the array. In a specific implementation, when applying BPSK modulation, this modulation state can include an open-circuit state and a short-circuit state. The modulated pilot signal includes both open-circuit and short-circuit pilot signals. Therefore, an open-circuit pilot signal is generated in the open-circuit state. A short-circuit pilot signal is generated by modulation under short-circuit conditions. .

[0095] It is worth noting that, for the sake of simplifying the analysis, this embodiment adopts a basic dual-state modulation scheme, that is, modulating the tag between open and short circuit states to achieve BPSK modulation. Nevertheless, the proposed system has strong adaptability and can easily support other modulation formats by adjusting the load impedance of the tag to change the reflection coefficient. 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 achieved.

[0096] Step 102: Using the receiver array, based on the received voltage corresponding to each modulated pilot signal and the original channel matrix of the region of interest, determine the clutter tag reflectivity and tag antenna reflectivity.

[0097] It should be noted that after the receiving array receives the modulated pilot signal, it will generate a corresponding receiving voltage. Since the original channel matrix of the region of interest describes the sensing 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 one specific embodiment of this example, step 102 includes the following sub-steps:

[0099] S21. Measure the open-circuit receiving voltage of the receiving array when it receives the open-circuit pilot signal and the short-circuit receiving voltage of the receiving array when it receives the 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 in these states can be expressed as:

[0101] (14)

[0102] (15)

[0103] In the formula, To receive voltage in an open circuit, This is the short-circuit received voltage.

[0104] S22. The clutter tag voltage component and tag antenna voltage component are determined by using open-circuit received voltage and short-circuit received voltage.

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

[0106] The sum of the open-circuit received voltage and the short-circuit received voltage is averaged to determine the clutter tag voltage component.

[0107] The difference between the open-circuit received voltage and the short-circuit received voltage is averaged to output the tag antenna voltage component.

[0108] It should be noted that the required voltage component can be recovered from the open-circuit received voltage and the short-circuit received voltage through the following linear combination. and :

[0109] (16)

[0110] (17)

[0111] S23. Based on the compressed sensing algorithm and the two-step iterative shrinking threshold algorithm, the clutter tag reflectivity is calculated and output based on the clutter tag voltage component and the original channel matrix of the region of interest.

[0112] It should be noted that, during the positioning phase, this embodiment requires, according to 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 itself sparse; furthermore, due to the total number of measurements... Typically less than the number of elements with unknown reflectivity. Therefore, the reconstruction problem in equation (18) is undetermined and belongs to the ill-posed problem. To solve this problem, this embodiment uses compressed sensing (CS) technology to represent the reconstruction process as follows: Norm minimization problem:

[0115] (19)

[0116] In the formula, express Norm; In order to effectively solve this optimization problem, this embodiment uses the two-step iterative shrinkage threshold (TwIST) algorithm for iterative solution. This algorithm combines iterative nonlinear shrinkage steps and adaptive parameter selection, making it particularly effective for sparse signal reconstruction in sensing applications.

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

[0118] It should be noted that, during the identification phase, a method similar to that used in sub-step S23 is employed based on the received voltage. reconstruction This achieves accurate label recognition. Therefore, based on equations (5), (12)-(13), the label will also be recovered. The expression is Norm minimization problem:

[0119] (20)

[0120] (twenty one)

[0121] This optimization problem can also be solved using the TwIST algorithm, because... This represents the reflectivity distribution associated with the tag's antenna pattern, and its reconstruction enables accurate tag identification.

[0122] This embodiment utilizes sparse reconstruction and inverse scattering techniques to improve sensing accuracy. After processing by compressed sensing (CS) algorithm, the structure mode component can accurately locate clutter scatterers and tags, while the antenna mode 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, firstly, the first location of a tag or clutter scatterer that may exist in the region of interest is located based on the reflectivity of the clutter tag. Then, the location of the tag is identified from the first location by the reflectivity of the tag antenna. The tag is accurately perceived and reconstructed through global environmental perception and local tag-specific identification.

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

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

[0127]

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

[0129] Original channel matrix Each column vector corresponds to the channel vector from the position of each grid cell within the DOI region to the receiving array. The tag antenna reflectivity determines which grid cell each tag is located in. Therefore, the channel vector corresponding to the grid cell where each tag is located can be derived from the original channel matrix. The extracted channel vectors are then combined to form a modified channel matrix. This is called the target channel matrix; because some grid cells of the DOI contain clutter scatterers, and clutter scatterers can cause interference, the modified channel matrix... A channel vector that does not contain the location of clutter scatterers, meaning it has removed the interference from clutter scatterers, can improve the performance of backscatter communication.

[0130] Step 105: Spatial modulation of the information bits to be transmitted is performed using the transmission array to generate constellation symbols and determine the active tag from each tag.

[0131] It should be noted that, in this embodiment, after completing the pilot signal-based positioning and identification process, each tag begins backscatter data transmission. Specifically, each tag uses an RF switch to dynamically select different load impedances. This adjusts the reflection coefficient. To achieve The modulated signal-reflection scheme, where these different reflection coefficient states directly correspond to the tag's transmitted signal. Number system constellation symbols; backscatter communication system in single tag ( In scenarios involving multiple labels, it functions as a single-input multiple-output (SIMO) system. In this scenario, it operates as a multiple-input multiple-output (MIMO) system. In order to comprehensively handle general situations, broaden the application scenarios, and adapt to more modulation techniques, this embodiment mainly focuses on the multi-tag MIMO backscatter communication scenario to further improve spectral efficiency and data rate.

[0132] In multi-tag environments, spatial modulation schemes such as SM and QSM are widely used. Spatial modulation (SM) activates only one antenna at a time for data transmission, eliminating inter-channel interference (ICI) and inter-antenna synchronization (IAS) requirements, thus improving bit error rate (BER) performance. Furthermore, it improves spectral efficiency by encoding additional bits into the antenna index. Advanced spatial modulation schemes, such as orthogonal spatial modulation (QSM), activate two antennas simultaneously to independently transmit the real and imaginary parts of a complex constellation symbol. Since the real and imaginary parts of this constellation symbol are modulated onto the corresponding real and imaginary parts of the carrier signal, respectively... In the imaginary part, QSM maintains the orthogonality between transmitted information to prevent inter-channel interference. Both SM and QSM transmit a total of two parts: constellation symbol bits and tag index bits. SM and QSM share the characteristic of transmitting only one constellation symbol at a time. The difference lies in that SM transmits additional information bits using only one tag index at a time, while QSM transmits additional information bits using two tag indices at a time. Therefore, QSM can transmit more information bits, achieving higher spectral efficiency than SM. In practical implementation, at the transmitting end, the information bits to be transmitted are first divided into two parts. One part of the bits is modulated and mapped to... The M-ary constellation symbol is used to select a tag by mapping another set of bits to the tag index, thereby determining the active tag, which is used to emit the M-ary constellation symbol.

[0133] Step 106: The constellation symbols are backscattered to the receiving array through the activation tag using the transmitting array, and the receiving array demodulates and decodes the output information bits based on the received signal of the constellation symbols and the target channel matrix.

[0134] It should be noted that, assuming the average transmit power is normalized to 1, the DOI contains... Each tag utilizes Channel State Information (CSI) obtained through antenna patterns during the localization and identification phases, while simultaneously... Voltage components of clutter scatterers and structural modes are removed. Then, the backscattered signal received after each symbol is transmitted, i.e., the received signal, can be expressed as:

[0135] (twenty two)

[0136] In the formula, For the first One tag, , For the first The constellation symbol transmitted by the tag, It is additive white Gaussian noise;

[0137] By using the original channel matrix The target channel matrix has been extracted and determined. In multi-label MIMO communication scenarios, the symbols transmitted by all tags constitute a signal vector. ,satisfy ,in It is the conjugate transpose. As expected, (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 tags, estimating the index of the transmitted constellation symbols and activation tags, and decoding and mapping the original information bits according to the demodulation results.

[0140] For example, when SM modulation is used: the SM scheme not only uses traditional The radix constellation symbols encode information bits, and the encoding also utilizes the index of the transmission tag. Its spectral efficiency is... ,forward Bit modulation zodiac symbols ,back Bit determines the active tag index Therefore, the transmission vector of SM Represented as:

[0141] (twenty four)

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

[0143] (25)

[0144] In the formula, yes The In 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 one complex constellation symbol. This method, which modulates the real and imaginary parts of the carrier signal onto their respective real and imaginary parts, can improve the spectral efficiency to [percentage missing]. At the same time, maintaining the orthogonality between transmitted information to prevent ICI; specifically, the first part Bit determines constellation symbol Part Two Bit mapping to tag index To transmit the real part Construct a vector The last part Bit mapping to tag index To transmit the real part Thus, the vector is obtained. Therefore, the transmitted signal vector is Accordingly, the received signal of the QSM is:

[0148] (27)

[0149] In the formula, and They are The and List, and The optimal ML detection for QSM is as follows:

[0150] (28)

[0151] in ;

[0152] After constructing the signal vector in the modulation stage, in the demodulation stage, the maximum likelihood detection described by equation (26) or (28) is used to traverse all possible constellation symbols and activation labels to construct all possible vectors. (or ), then find (or ) and received signal vector (or Given the Euclidean distance between two vectors, find the vector corresponding to the smallest Euclidean distance. (or By doing so, the constellation symbol and the index of the activation tag can be estimated, thus completing the demodulation.

[0153] To further illustrate the backscatter communication performance of this embodiment, 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 discretized into Each grid cell measures [number] grid cells. Therefore, it is necessary to estimate One unknown parameter; both the transmit and receive arrays are implemented as uniform linear arrays (ULA), each array consisting of... It consists of a patch antenna grid.

[0156] B. Positioning and identification performance:

[0157] To quantitatively evaluate the performance of the sensing system, Peak Signal-to-Noise Ratio (PSNR) is used as the performance metric; a higher PSNR value indicates better image reconstruction. In the reconstructed image, white rectangles indicate the actual location of the tags, while green boxes represent the actual locations of clutter scatterers. The tags are all modeled as copper dipole antennas, each with a radius of [missing information]. The height is .

[0158] Figure 3 The results of perception in multiple labeled scenarios are shown, in which four labels are placed together with copper clutter scatterers of different sizes; Figure 3 (a) The display system accurately reconstructed the locations of all four tags and clutter scatterers, and then selected from the four available tags that contained... A subset of labels is evaluated, and all possible combinations are assessed, totaling... Various configurations; 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 result shown in (o) This clearly demonstrates that the proposed system consistently and accurately identifies and locates each label across all test combinations; The reconstructed PSNR values ​​were (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 tags.

[0159] C. Backscatter communication performance

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

[0161] In the V-BLAST scheme, all available tags simultaneously transmit independent symbols, achieving spectral efficiency. In the receiver array, minimum mean square error (MMSE) estimation is used to detect the transmitted symbols, as shown below:

[0162] (29)

[0163] In the formula, The signal vector estimated by V-BLAST, Let Variance be the noise variance. It is a dimension of The identity matrix, The received signal is from V-BLAST;

[0164] Figure 4 The BER performance of SM was compared with that of the vertical clock laboratory layered spatiotemporal (V-BLAST) and SIMO schemes at spectral efficiencies of 3 and 4 bits / Hz. The results show that SM outperforms V-BLAST and SIMO, and this advantage becomes more pronounced at higher signal-to-noise ratio (SNR) values. At the same time, compared with V-BLAST and SIMO, SM achieves a performance gain of approximately 2dB and 5dB, respectively; at 4 bits / second / Hz, the advantage of SM increases further, achieving a performance gain of more than 2dB compared with V-BLAST and approximately 6dB compared with SIMO; these results clearly show that as the spectral efficiency increases, the advantage of SM becomes greater and greater.

[0165] Figure 4 This further illustrates the performance comparison between SM and QSM in the backscatter communication framework at spectral efficiencies of 4 bits / s / Hz, 6 bits / s / Hz, and 7 bits / s / Hz; and at 4 bits / s / Hz and BER of... At that time, the BER performance of QSM lagged behind that of SM by about 2dB; however, at higher spectral efficiencies of 6bits / s / Hz and 7bits / s / Hz, this trend reversed, with QSM outperforming SM by about 5dB and 2.5dB, respectively.

[0166] In this embodiment of the invention, compared to existing sensing system research, such as sensing systems employing orthogonal coding active illumination imaging, bifacial reflection imaging, millimeter-wave imaging, and Fourier algorithm-based sensing systems, most rely on wide bandwidths and require the deployment of numerous antennas. This not only significantly increases hardware costs and system complexity but also makes it difficult to adapt to the increasingly scarce spectrum resources of the 6G era. Furthermore, previous sensing systems using backscattering technology are limited to sensing clutter scatterers and cannot provide accurate positioning for tags in backscattering communication systems. More importantly, the aforementioned sensing systems typically focus on improving sensing performance and lack the integration of communication functions, making them unsuitable for effective application within the ISAC framework. To address the aforementioned research... To overcome the limitations of previous methods, the proposed method in this embodiment seamlessly combines backscattering sensing with spatially modulated backscattering communication using SM and QSM technologies. By dynamically modulating the tag state, it can effectively separate the structure mode component and the antenna mode component, thereby helping to accurately extract scattering characteristics and accurately locate and identify backscattering tags in cluttered environments. By integrating spatial modulation into backscattering communication, it further improves the performance in multi-antenna scenarios, achieving high spectral efficiency and low power consumption backscattering communication. It can also maintain robust performance even when array and available spectrum resources are limited. Furthermore, by using compressed sensing-assisted backscattering for localization, it also reduces hardware complexity and alleviates spectrum congestion.

[0167] Please see Figure 6 , Figure 6 This is a structural block diagram of a synchronous sensing and backscattering communication device based on spatial modulation and backscattering, provided in an embodiment of the present invention.

[0168] This invention provides a synchronous sensing and backscattering communication device based on spatial modulation and backscattering, comprising 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 modulate the load impedance of the tag to generate multiple modulated pilot signals of the pilot signal after transmitting a pilot signal to the tag through the transmitting array and backscattering them to the receiving array.

[0170] The reflectivity determination module 602 is used to determine the clutter tag reflectivity and 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.

[0171] The tag sensing module 603 is used to locate the first position of the clutter scatterer and the tag based on the clutter tag reflectivity, and to identify the tag from the first position using the 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] The bit modulation module 605 is used to spatially modulate the information bits to be transmitted through the transmission array, generate constellation symbols, and determine the active tag from each tag.

[0174] The communication decoding module 606 is used to backscatter constellation symbols to the receiving array through the activation tag using the transmitting array, and to demodulate and decode the output information bits based on the received signal of the constellation symbols and the target channel matrix using 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 used for:

[0176] Transmit pilot signals to the tag via the transmitting antenna;

[0177] The load impedance of the modulation tag is in an open-circuit state, and the tag generates an open-circuit pilot signal corresponding to the received pilot signal.

[0178] When the load impedance of the modulation tag is in a short-circuit state, the tag generates a short-circuit pilot signal corresponding to the received pilot signal.

[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 used for:

[0181] The open-circuit receiving voltage of the receiving array when it receives an open-circuit pilot signal and the short-circuit receiving voltage when it receives a short-circuit pilot signal are measured.

[0182] The clutter tag voltage component and tag antenna voltage component are determined using open-circuit and short-circuit received voltages.

[0183] Based on the compressed sensing algorithm and the two-step iterative shrinking threshold algorithm, the clutter tag reflectivity is solved by the clutter tag voltage component and the original channel matrix of the region of interest.

[0184] The tag antenna reflectivity is calculated based on the tag antenna voltage component and the original channel matrix using compressed sensing algorithm and two-step iterative shrinking threshold algorithm.

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

[0186] Electromagnetic simulation is performed on the region of interest to determine the incident electric fields of the transmitting and receiving arrays at various locations within the region of interest.

[0187] The channel vectors corresponding to the incident electric fields at each location are calculated, and the original channel matrix is ​​formed by combining the channel vectors.

[0188] Furthermore, the clutter tag voltage component and tag antenna voltage component are determined using open-circuit received voltage and short-circuit received voltage, including:

[0189] The sum of the open-circuit received voltage and the short-circuit received voltage is averaged to determine the clutter tag voltage component.

[0190] The difference between the open-circuit received voltage and the short-circuit received voltage is averaged to output the tag antenna voltage component.

[0191] Furthermore, the received signal specifically includes:

[0192] ;

[0193] in, , ;

[0194] In the formula, In order to receive signals, For the target channel matrix, To activate the tag's constellation-symbol-based transfer vector, It is additive white Gaussian noise. For the first One tag, For the first The constellation symbol transmitted by the tag, For the total number of tags, As expected, This is the conjugate transpose.

[0195] This invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program; when the computer program is executed by the processor, the processor performs the steps of the synchronous sensing and backscattering communication method based on spatial modulation and backscattering as described in any of the above embodiments.

[0196] This invention also provides a computer-readable storage medium storing a computer program / instructions thereon, which, when executed by a processor, implements the steps of the synchronous sensing and backscattering communication method based on spatial modulation and backscattering as described in any of the above embodiments.

[0197] This 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 described in any of the above embodiments.

[0198] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the above-described device and module can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0199] In the several embodiments provided in this application, it should be understood that the disclosed apparatus 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 through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0200] 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.

[0201] 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.

[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, 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.

[0203] 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 synchronous sensing and backscattering communication method based on spatial modulation and backscattering, characterized in that, The application relates to a transmitting array, a receiving array and a region of interest, the region of interest containing clutter scatterers and tags; the method comprises the following steps: After the transmitting array transmits pilot signals to the tags, the load impedance of the tags is modulated to generate multiple modulated pilot signals of the pilot signals and backscatter to the receiving array; Based on the received voltage corresponding to each modulated pilot signal and the original channel matrix of the region of interest, the receiving array determines the clutter tag reflectivity and the tag antenna reflectivity; Based on the clutter tag reflectivity, the first positions of the clutter scatterers and the tags are located, and the tags are identified from the first positions based on the tag antenna reflectivity; From the original channel matrix, a target channel matrix of the tags is extracted according to the tag antenna reflectivity; The transmitting array spatially modulates the information bits to be transmitted, generates constellation symbols and determines the activated tags from the tags; The transmitting array backscatters the constellation symbols to the receiving array through the activated tags, and the receiving array demodulates and decodes the output information bits based on the received signals of the constellation symbols and the target channel matrix.

2. The spatial modulation and inverse scattering based simultaneous sensing and backscattering communication method of claim 1, wherein, The modulated pilot signals include open circuit pilot signals and short circuit pilot signals; after the transmitting array transmits pilot signals to the tags, the load impedance of the tags is modulated to generate multiple modulated pilot signals of the pilot signals and backscatter to the receiving array, which comprises the following steps: The transmitting array transmits pilot signals to the tags; The load impedance of the tags is in an open circuit state, and the tags generate open circuit pilot signals corresponding to the received pilot signals; After the load impedance of the tags is in a short circuit state, the tags generate short circuit pilot signals corresponding to the received pilot signals; The open circuit pilot signals and the short circuit pilot signals are backscattered to the receiving array.

3. The spatial modulation and inverse scattering based simultaneous sensing and backscattering communication method of claim 2, wherein, Based on the received voltage corresponding to each modulated pilot signal and the original channel matrix of the region of interest, the receiving array determines the clutter tag reflectivity and the tag antenna reflectivity, which comprises the following steps: The open circuit receiving voltage of the receiving array receiving the open circuit pilot signals and the short circuit receiving voltage of the receiving array receiving the short circuit pilot signals are measured; 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; 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; According to the compressed sensing algorithm and the two-step iterative shrinkage threshold algorithm, the tag antenna reflectivity is solved based on the tag antenna voltage component and the original channel matrix.

4. The spatial modulation and inverse scattering based simultaneous sensing and backscattering communication method of claim 1, wherein, The determination process of the original channel matrix comprises the following steps: The electromagnetic simulation of the region of interest is performed 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 original channel matrix is composed of all the channel vectors.

5. The spatial modulation and inverse scattering based simultaneous sensing and backscattering communication method of claim 3, wherein, 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, which comprises the following steps: The sum of the open circuit receiving voltage and the short circuit receiving voltage is subjected to mean value operation to determine the clutter tag voltage component; The difference between the open-circuit receiving voltage and the short-circuit receiving voltage is averaged to output a tag antenna voltage component.

6. The spatial modulation and inverse scattering based simultaneous sensing and backscattering communication method of claim 1, wherein, The receiving signal specifically includes: ； wherein , ; wherein is a received signal, is a target channel matrix, is an active tag based constellation symbol transmission vector, is an additive white Gaussian noise, is a jth tag, is a jth tag transmission constellation symbol, is a total number of tags, is an expectation, is a conjugate transpose.

7. A spatial modulation and inverse scattering based simultaneous sensing and backscattering communication apparatus, characterized in that, The method relates to a transmitting array, a receiving array and a region of interest, and the region of interest contains a clutter scatterer and a tag; the device comprises: A pilot scattering module is configured to modulate the load impedance of the tag to generate a plurality of modulated pilot signals of the pilot signal and backscatter to the receiving array after the transmitting array transmits the pilot signal to the tag; A reflectivity determination module is configured to determine the clutter tag reflectivity and the tag antenna reflectivity by using the receiving array to generate a receiving voltage corresponding to each modulated pilot signal and an original channel matrix of the region of interest; A tag sensing module is configured to locate a first position of the clutter scatterer and the tag based on the clutter tag reflectivity, and identify the tag from the first position based on the tag antenna reflectivity; A channel correction module is configured to extract a target channel matrix of the tag from the original channel matrix according to the tag antenna reflectivity; A bit modulation module is configured to spatially modulate information bits to be transmitted by the transmitting array to generate constellation symbols and determine an active tag from each tag; A communication decoding module is configured to backscatter the constellation symbols to the receiving array by the active tag through the transmitting array, and demodulate and decode output information bits based on a receiving signal of the constellation symbols and the target channel matrix by the receiving array.

8. A computer device, comprising: The computer program / instruction is executed by the processor to realize the steps of the spatial modulation and inverse scattering based synchronous sensing and inverse scattering communication method according to any one of claims 1-6.

9. A computer readable storage medium having stored thereon computer programs / instructions, characterized in that, The computer program / instruction is executed by the processor to realize the steps of the spatial modulation and inverse scattering based synchronous sensing and inverse scattering communication method according to any one of claims 1-6.

10. A computer program product comprising computer programs / instructions, characterized in that, The computer program / instruction is executed by the processor to realize the steps of the spatial modulation and inverse scattering based synchronous sensing and inverse scattering communication method according to any one of claims 1-6.

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