A multi-antenna backscatter communication method, apparatus and system

Abstract

This invention discloses a multi-antenna backscatter communication method, apparatus, and system, belonging to the field of wireless communication technology. The method includes: an environmental excitation source transmitting an excitation signal; a multi-antenna backscatter tag reflecting the excitation signal by selecting an antenna and controlling an impedance network, simultaneously achieving multi-dimensional mapping of tag information; a receiver decoupling the coupling channels of the direct-fire link and the cascaded backscatter link based on the joint pilot corresponding to the multi-antenna backscatter tag and the environmental excitation source, and estimating the channels of the direct-fire link and the cascaded backscatter link respectively; based on the estimated decoupled channels, first detecting the environmental excitation source signal, and then detecting the multi-dimensional mapped backscatter signal based on the signal characteristics between the links. This invention provides a unified application framework for multi-antenna backscatter tags, enabling tags to flexibly utilize spatial, temporal, and index dimension resources for information mapping, achieving high-speed and high-reliability backscatter transmission.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, and more specifically, relates to a multi-antenna backscatter communication method, apparatus, and system. Background Technology

[0002] Backscatter communication loads the information bits to be transmitted onto the incident environmental excitation source signal by reflecting radio frequency signals from the environment. It does not require generating its own radio frequency signal, thus eliminating the need for traditional high-power analog devices such as high-frequency oscillators and analog-to-digital converters. This results in advantages such as ultra-low power consumption at the microwatt level and reduced equipment manufacturing costs. Therefore, as the most energy-efficient passive communication paradigm, backscatter communication is considered one of the key technologies supporting the trillion-level interconnection of the future Internet of Things.

[0003] Because backscattered signals experience deep fading in cascaded channels and rely solely on impedance modulation for signal scattering, their transmission rate and reliability are limited. Improving their communication transmission performance is a key challenge for the commercial application of backscattering. Inspired by the use of multi-antenna technology in traditional cellular and Wi-Fi communications to enhance uplink transmission rates and reliability, applying Multi-Input Multi-Output (MIMO) technology to backscattering is considered a potential solution to overcome its performance limitations. Currently, research has been conducted on multi-antenna backscattering transmission technologies based on space-time coding and spatial modulation. Space-time coding-based backscattering utilizes the space-time dimension to achieve transmit diversity, improving transmission reliability, but its transmission rate remains unchanged compared to single-antenna backscattering. Spatial modulation-based backscattering uses the antenna index dimension as an additional information source to increase transmission rate, but its transmission reliability is difficult to guarantee due to the susceptibility of channel differences to propagation environmental factors. Current research on multi-antenna backscattering only focuses on the design of MIMO technology in a single dimension, which cannot simultaneously and flexibly balance design complexity with diversity and multiplexing gain, and often relies on ideal and perfect channel information, making it difficult to apply in practice.

[0004] In summary, how to design a multi-antenna backscatter communication method and corresponding devices and systems that can flexibly utilize multi-dimensional resources for backscatter information mapping is an urgent problem to be solved. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a multi-antenna backscatter communication method, apparatus, and system. Its purpose is to decouple the coupling channels of the direct-fire link and the cascaded backscatter link based on the joint pilot signals corresponding to the multi-antenna backscatter tag and the environmental excitation source, thereby achieving separate estimation of the channels of the direct-fire link and the cascaded backscatter link. The estimated decoupled channels are then used to detect the environmental excitation source signal and the backscatter signal, thus solving the technical problems of low information transmission rate and low transmission reliability in backscatter communication.

[0006] To achieve the above objectives, according to one aspect of the present invention, a multi-antenna backscatter communication method is provided, comprising:

[0007] S1: Emitter signal is emitted using an environmental excitation source;

[0008] S2: Control the selection of antennas and impedance networks for multi-antenna backscattering tags to achieve multi-dimensional mapping of tag information while the tag reflects the excitation signal;

[0009] S3: The control receiver decouples the coupling channels of the direct link and the cascaded backscattering link according to the joint pilot corresponding to the multi-antenna backscattering tag and the environmental excitation source, thereby realizing the separate estimation of the channels of the direct link and the cascaded backscattering link; the environmental excitation source signal is detected according to the estimated channel, and then the backscattering signal of the multi-dimensional mapping is detected according to the signal characteristics between the links.

[0010] In one embodiment, S2 includes: controlling the multi-antenna backscattering tag to perform the following steps:

[0011] Different antennas are selected and activated from candidate antennas in different time slots to achieve index dimension mapping of backscatter information; impedance selection is selected to achieve space shift keying-backscatter modulation and space-backscatter modulation effects respectively;

[0012] By selecting multiple antennas and simultaneously selecting impedance networks, and controlling the impedance values ​​and signal characteristics between time slots, spatial-spacetime backscattering and spatial-vertical layered-backscattering modulation effects are achieved respectively, thereby realizing multi-dimensional mapping of backscattering information in the index and spatial-time dimensions.

[0013] In one embodiment, the joint pilot design is divided into two parts; the first part of the pilot is used for information estimation of the direct-link channel, and has a length of 2; the second part of the pilot is used for sequential estimation of the cascaded backscatter channel information corresponding to the antenna activated by the tag, and has a length of [missing information].

[0014] Where K is the number of active tag antennas, and N is the total number of tag antennas; the last time slot of the first part of the pilot and the first time slot of the second part of the pilot are two shared time slots, the length of which is 1. The total length of the joint pilot is...

[0015] In one embodiment,

[0016] In the first part of the pilot, the environmental excitation source transmits the same pilot symbol in two consecutive time slots, and the antenna activated by the tag transmits pilot symbols with opposite phases.

[0017] The second part of the pilot signal is divided according to the number of selected active antenna combinations. In each combination, the pilot symbols transmitted by the environmental excitation source remain the same within K time slots, and the pilot matrix transmitted by the active tag antenna within K time slots has full-rank characteristics.

[0018] In one embodiment, S3 includes controlling the receiver to perform the following steps:

[0019] S31: The direct-fire link channel is estimated by averaging the received signals from two consecutive time slots based on the joint pilot signals of the environmental excitation source and the backscattering tag and dividing by the excitation source pilot symbols in the first part of the pilot signal; the cascaded backscattering channels corresponding to different active antenna combinations are sequentially estimated using the joint pilot signals of the multi-antenna backscattering tag and the environmental excitation source.

[0020] S32: Detect the environmental excitation source signal based on the estimated decoupling channel, and then detect the backscattered signal of the multi-dimensional mapping based on the signal characteristics between links.

[0021] In one embodiment, S32 includes: first estimating the environmental excitation source signal based on the maximum likelihood principle according to the signal characteristics between links, and then combining the estimated direct link channel to achieve interference cancellation of the direct link in the received signal of the receiver, thereby realizing the joint detection of multi-antenna tags in index and spatiotemporal dimension information.

[0022] According to another aspect of the present invention, a multi-antenna backscatter communication device is provided for performing the aforementioned multi-antenna backscatter communication method, comprising:

[0023] An environmental excitation source is used to transmit excitation signals;

[0024] A multi-antenna backscattering tag is used to reflect the excitation signal by selecting antennas and controlling the impedance network, thereby achieving multi-dimensional mapping of tag information.

[0025] The receiver is configured to decouple the coupling channels of the direct-fire link and the cascaded backscattering link based on the joint pilot signals corresponding to the multi-antenna backscattering tags and the environmental excitation source, thereby achieving separate estimation of the channels of the direct-fire link and the cascaded backscattering link; detect the environmental excitation source signal based on the estimated decoupled channels, and then detect the backscattering signal of the multi-dimensional mapping based on the signal characteristics between the links.

[0026] According to another aspect of the present invention, a multi-antenna backscatter communication system is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described method.

[0027] According to another aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0028] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0029] (1) This invention provides a multi-antenna backscatter communication method, wherein the multi-antenna backscatter tag can flexibly utilize antenna selection and impedance network switching to achieve flexible selection and combination of spatial-temporal domain and index domain, realizing multi-dimensional mapping, which can significantly improve the information transmission rate and transmission reliability of backscatter. This invention provides a unified application framework for multi-antenna backscatter tags, enabling tags to flexibly utilize spatial, temporal, and index dimension resources for information mapping, achieving high-speed and high-reliability backscatter information transmission.

[0030] (2) By designing the receiver using joint pilots, decoupling estimation of the direct-link channel and the cascaded backscattered channel can be achieved separately. Simultaneously, the joint pilots can also achieve sequential estimation of the cascaded backscattered channel information under any number of active antennas. Furthermore, based on the estimated decoupled channel, the receiver can utilize the superposition characteristics between links to eliminate interference in the direct-link channel and achieve joint estimation of multi-dimensional information from multiple antennas, significantly improving the detection performance of multi-dimensional backscattered signals. Attached Figure Description

[0031] Figure 1 A flowchart of a multi-antenna backscatter communication method provided in an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the principle of a multi-antenna backscatter tag for a multi-antenna backscatter communication method provided in an embodiment of the present invention;

[0033] Figure 3This is a pilot design diagram for a multi-antenna backscatter communication method provided in an embodiment of the present invention;

[0034] Figure 4 A receiver flowchart for a multi-antenna backscatter communication method provided in an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of a multi-antenna backscatter communication device provided in an embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram of a multi-antenna backscatter communication system provided in an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below may be combined with each other as long as they do not conflict with each other.

[0038] like Figure 1 As shown, the present invention provides a multi-antenna backscatter communication method, comprising:

[0039] S1: Emitter signal is emitted using an environmental excitation source;

[0040] S2: Control the selection of antennas and impedance networks for multi-antenna backscattering tags to achieve multi-dimensional mapping of tag information while the tag reflects the excitation signal;

[0041] S3: The control receiver decouples the coupled channels of the direct-fire link and the cascaded backscattering link based on the joint pilot signals corresponding to the multi-antenna backscattering tags and the environmental excitation source, thereby achieving separate estimation of the channels of the direct-fire link and the cascaded backscattering link; it detects the environmental excitation source signal based on the estimated channel, and then detects the backscattering signal of the multi-dimensional mapping based on the signal characteristics between the links.

[0042] Specifically, the modulation method used by the multi-antenna backscattering tag in S2 when reflecting environmental excitation source signals can be flexibly selected. It can select and activate different reflecting antennas to achieve index domain modulation, or control the impedance network to achieve spatial-temporal domain modulation of the wireless signal. Moreover, these modulation methods can be combined.

[0043] See Figure 2 In this application example, the multi-antenna backscatter tag can achieve spatial, temporal, and index domain modulation of signals by selectively activating one or more antennas and flexibly controlling the impedance network.

[0044] Specifically, multi-antenna backscatter tags achieve space-backscatter modulation and space-shift keying-backscatter modulation by selecting antennas and switching impedances, respectively. Similarly, multi-antenna backscatter tags can simultaneously control the states of multiple RF switches to activate multiple antennas. If two antennas are activated, the multi-antenna backscatter tag can transmit different symbols by selecting different impedances. Simultaneously, by controlling the reflection coefficients of different time slots, multi-antenna backscatter tags can achieve space-vertical layered backscatter modulation and space-space-time backscatter modulation. Furthermore, multi-antenna backscatter tags can generate square wave signals by controlling the switching frequency of the RF switches to determine whether to frequency-shift the incident wireless signal. The period and phase of the square wave signal are determined by the magnitude of the frequency shift and the number of transmitted bits.

[0045] Taking a typical MIMO-backscattering system consisting of a multi-antenna backscattering tag with N antennas, a receiver with L antennas, and a single-antenna environmental excitation source as an example, the following describes how the gains in diversity, multiplexing, and spatial aspects of MIMO modulation are achieved on the multi-antenna backscattering tag.

[0046] Implementation of the Space Shift Keying (SSK) Backscatter Modulation Scheme: In the SSK-backscatter modulation scheme, a multi-antenna backscatter tag activates only one antenna in each transmission time slot to reflect the excitation source signal, generating a backscatter signal. This signal has two characteristics: 1) The corresponding backscatter signal vector is sparse, with only one non-zero element whose index corresponds to the number of active antennas; the remaining elements are represented as 0, indicating that the antennas are inactive. 2) The activated antennas are not impedance-selective. We use a microcontroller to control the state of the RF switches, thereby utilizing the spatial mapping of information bits based on the differences in the cascaded backscatter channels between antennas. It is worth noting that traditional SSK requires an RF link to implement its mapping process; we implement this using a microcontroller in multi-antenna backscatter tags.

[0047] Spatial Modulation (SM)-Backscatter Modulation Scheme Implementation: In the spatial-backscatter modulation scheme, the multi-antenna backscatter tag divides the transmitted bits of length log2(N) + log2(M) into two parts: 1) log2(N) bits are mapped to the index of the activated antenna; 2) log2(M) bits are mapped to the constellation symbol of modulation order M. The first part of the mapping process is similar to the spatial mapping process in the Space Shift Keying-Backscatter Modulation scheme, and is achieved by controlling the state of the RF switch; the second part of the mapping process, by selecting the impedance load of the activated antenna, forms the reflection coefficient of the tag antenna, i.e., the tag transmits the constellation symbol. Through the mapping of the two parts of the signal, the backscatter signal in this modulation mode is formed. The difference between this signal and the backscatter signal in the Space Shift Keying-Backscatter Modulation scheme is that the non-zero elements in the sparse signal vector are represented by the reflection coefficient, adding an additional dimension of information transmission.

[0048] Implementation of Spatial-Vertical-Blast (SM-VBLAST) Backscatter Modulation: In the spatial-vertical-blast-backscatter modulation scheme, the N-tag antennas are divided into several antenna groups, each containing K antennas. Each antenna group undergoes spatial-backscatter mapping; that is, K antennas are activated in each time slot, and impedance selection is performed on each activated antenna. The impedance selection is determined by the bits to be transmitted in the backscattered tag. Therefore, the backscattered signal formed during this modulation process can be considered as a combination of multiple sparse spatial-backscattered signals. Furthermore, since the spatial-vertical-blast-backscatter modulation scheme activates and selects multiple antennas based on spatial dimension mapping, it can achieve multiplexing gain similar to that in MIMO systems, significantly improving the transmission rate of backscattered symbols.

[0049] Spatial Modulation-Space Time Block Code (SM-STBC) backscatter modulation is used to achieve this. The SM-STBC scheme provides spatial diversity gain for tags by employing a space-time block code structure. Unlike the SM-Vertical Layered Backscatter Modulation scheme, this approach not only activates multiple antennas but also controls the impedance network to ensure that the backscattered signals between different time slots exhibit signal characteristics similar to those of SM-STBC (code rates can be 1, 3 / 4, etc.). Specifically, the impedance network can be selected and switched via a control module to form a signal matrix composed of the desired reflection coefficients. The reflection coefficients between different time slots in this signal matrix are determined by the selected space-time coding scheme with a specific code rate; different code rates correspond to different transmission rates.

[0050] The above modulation scheme can be flexibly selected in multi-antenna backscatter tags according to system requirements.

[0051] In one embodiment, the joint pilot design is as follows:

[0052] The pilot time slot length is related to the number of reflecting antennas on the multi-antenna backscattering tag, and the total pilot design length is... Where N represents the total number of antennas in the multi-antenna backscattering tag, and K represents the number of active backscattering antennas. The first part of the design addresses the direct-link channel information and has a length of 2; the second part is designed for sequentially estimating the cascaded backscattering channel information corresponding to the active antennas of the tag, and has a length of [missing information]. Meanwhile, the end time slot of the first part and the beginning time slot of the second part are shared time slots between the two parts.

[0053] In the first part of the pilot signal, the environmental excitation source continuously transmits two identical symbols, and the pilot symbol vectors transmitted by the antenna selected by the tag in the two time slots of the first part are out of phase. The second part of the pilot signal can be divided according to the number of selected active antenna combinations. In each combination, the environmental excitation source pilot symbols remain the same across K time slots, and the pilot matrix transmitted by the activated tag antenna within K time slots has full-rank characteristics.

[0054] In one embodiment, in S3, the receiver uses the received pilot signals to estimate the direct-fire link channel information and the cascaded backscatter link channel information corresponding to different antenna combinations.

[0055] See Figure 3 Without loss of generality, the diagram illustrates a pilot design scheme for a multi-antenna backscattering tag with N=4 and K=2. The pilot time slot length is designed to be... The signal vectors transmitted by the tag in the first two time slots must be summed to form a vector with zero elements, meaning the symbols transmitted by the activated antenna in two consecutive time slots must be out of phase. Secondly, the second part has a length of... The pilots for the tag and excitation source can be further divided into K groups. In each group, the pilot symbols transmitted by the excitation source in each time slot remain the same, and the pilot symbols transmitted by the tag form a full-rank matrix.

[0056] First, the direct-link channel is estimated using the phase change of the reflection coefficient: two antennas are selected to backscatter according to the designed pilot signals. Since the pilot signals of the first two time slots of the tag are vectors with opposite phases, the addition of the first two received signal vectors of the receiver can directly eliminate the backscattered link information. Then, by averaging and removing the estimated excitation source symbol, the direct-link channel can be estimated. It is worth noting that S3 can be applied to backscattering systems with any number of tag antennas, achieving channel decoupling and estimation of direct-link channel information even without knowing the cascaded backscattered channel. After obtaining the direct-link channel information, the cascaded backscattered channel information of the selected antenna combination is further estimated. Specifically, after obtaining the direct-link channel, combined with the designed excitation source signal pilot of each time slot, the direct-link signal can be removed from the received signal at the receiver, and then the received signal components consisting only of the cascaded backscattered channel and the designed tag pilot can be calculated. Combining the orthogonality of the tag pilot signals, the cascaded backscattered channel corresponding to the activated antennas can be obtained through matrix operations. Based on this principle, by sequentially activating K tag antennas in different combinations, we can obtain the cascaded backscattering channel corresponding to each tag antenna combination. Furthermore, if the tag employs a special frequency shifting mechanism to avoid direct path interference, the cascaded backscattering channel estimation process can also adopt the principle of full-rank tag pilot design proposed in this patent.

[0057] The above process is applicable to both the excitation source and the number of tag antennas, and has design versatility.

[0058] In one embodiment, channel state estimation is performed based on the designed pilot signals. First, the channel information from the environmental excitation source to the receiver is estimated. Then, the direct link and the cascaded backscattered link are separated, and the cascaded backscattered channel information from the environmental excitation source to the tag and then to the receiver is estimated. Due to double attenuation, the cascaded backscattered link has high path loss. Therefore, the direct link signal component is a stronger interference component than the multi-antenna backscattered tag reflection signal. Based on the estimated decoupled channel, the direct link interference is eliminated by subtracting the signal component of the direct link. Then, the multi-dimensional mapped backscattered signal is detected based on the estimated cascaded backscattered channel information.

[0059] Specifically, as shown in Figure 4, firstly, in time slot t, the receiver detects the signal of the direct link with a larger signal component strength. Using the principle of maximum likelihood search, by exhaustively enumerating all possible excitation source signal vectors s(t), the relationship between the received signal and the received signal is calculated. The Euclidean distance between them is used to determine the excitation source signal and thus estimate it. This refers to the direct link channel estimated above.

[0060] To detect multi-dimensional information of backscattered tags in multi-antenna environments, the direct-link signal component is first removed from the received signal. Then, the estimated cascaded backscattered channel information is combined with this information. The optimal detection can be obtained by combining the tag's index information and spatiotemporal information with maximum likelihood. This enables the detection of backscattered signals from multi-antenna tags with arbitrary modulation schemes.

[0061] This detection method utilizes the characteristic that the signal strength of the direct-light link is relatively stronger than that of the cascaded backscattered link to remove the direct-light link, thereby achieving interference-free detection of backscattered signals from multiple antennas. It features high reliability and is suitable for MIMO backscattered systems with any number of antennas and any modulation scheme.

[0062] This embodiment illustrates a multi-antenna backscatter communication system. It includes a control module, a synchronization module, a clock module, and a radio frequency front-end module; specifically, the multi-antenna backscatter tag comprises the above four basic modules, such as... Figure 5 As shown.

[0063] Control module: Uses a low-power FPGA as the central processing unit to generate control signals, realize the selection of antenna and corresponding load impedance, and control multi-dimensional signal mapping;

[0064] Synchronization module: Uses an energy detector to detect whether the environmental excitation source is sending a signal, and is used to synchronize the multidimensional backscattered signal and the environmental excitation source signal in time;

[0065] Clock module: Uses a crystal oscillator to generate the system clock signal to ensure the timing relationship between the multidimensional backscattered signal and the environmental excitation source signal;

[0066] RF front-end module: Composed of RF switch and antenna. The RF switch can select different antennas and corresponding load impedances according to the control signal to realize multi-dimensional signal mapping.

[0067] Compared to single-antenna backscatter tags, this design only increases the number of switches and antennas in the index dimension mapping, thus maintaining ultra-low power consumption.

[0068] like Figure 6 As shown, the present invention provides a multi-antenna backscatter communication device for performing a multi-antenna backscatter communication method, comprising:

[0069] An environmental excitation source is used to transmit excitation signals;

[0070] Multi-antenna backscattering tags are used to reflect excitation signals by selecting antennas and controlling impedance networks, thereby achieving multi-dimensional mapping of tag information.

[0071] The receiver is used to decouple the coupled channels of the direct-fire link and the cascaded backscattering link based on the joint pilot signals corresponding to the multi-antenna backscattering tags and the environmental excitation source, thereby enabling separate estimation of the channels of the direct-fire link and the cascaded backscattering link; it detects the environmental excitation source signal based on the estimated decoupled channels, and then detects the backscattered signal of the multi-dimensional mapping based on the signal characteristics between the links.

[0072] According to another aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0073] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-antenna backscatter communication method, characterized in that, include: S1: Emitter signal is emitted using an environmental excitation source; S2: Controlling the selection of antennas and impedance networks for multi-antenna backscattering tags to achieve multi-dimensional mapping of tag information while the tags reflect the excitation signal; S2 includes: controlling the multi-antenna backscattering tags to perform the following steps: selecting and activating different antennas from candidate antennas in different time slots to achieve index-dimensional mapping of backscattering information; selecting whether to perform impedance selection to achieve space-shift keying-backscattering modulation and space-backscattering modulation effects respectively; selecting multiple antennas and simultaneously performing impedance network selection, and by controlling the impedance value and signal characteristics between time slots, achieving space-space-time backscattering and space-vertical layering-backscattering modulation effects respectively, thereby achieving multi-dimensional mapping of backscattering information in the index and space-time dimensions; S3: The control receiver decouples the coupling channels of the direct-fire link and the cascaded backscattering link according to the joint pilot corresponding to the multi-antenna backscattering tag and the environmental excitation source, thereby estimating the channels of the direct-fire link and the cascaded backscattering link respectively; it detects the excitation signal according to the estimated channel, and then detects the backscattering signal of the multi-dimensional mapping according to the signal characteristics between the links.

2. The multi-antenna backscatter communication method as described in claim 1, characterized in that, The joint pilot design is divided into two parts; the first part, with a length of 2, is used for channel information estimation of the direct-fire link; the second part, with a length of 2, is used for sequential estimation of the channel information of the cascaded backscattered link corresponding to the antenna activated by the tag. ; in, Number of antennas activated for the tag N The total number of tag antennas; the last time slot of the first part of the pilot and the first time slot of the second part of the pilot are two shared time slots, the length of which is 1. The total length of the joint pilot is... .

3. The multi-antenna backscatter communication method as described in claim 2, characterized in that, In the first part of the pilot, the environmental excitation source transmits the same pilot symbol in two consecutive time slots, and the antenna activated by the tag transmits pilot symbols with opposite phases. The second part of the pilot signal is divided according to the number of selected active antenna combinations. In each group, the pilot symbols transmitted by the environmental excitation source are in The same applies within each time slot, and the active tag antenna remains in The pilot matrix transmitted within a time slot has full rank characteristics.

4. The multi-antenna backscatter communication method as described in claim 1, characterized in that, S3 includes controlling the receiver to perform the following steps: S31: Based on the joint pilot signal of the environmental excitation source and the backscattering tag, the channel of the direct-fire link is estimated by averaging the received signals of two consecutive time slots and dividing by the excitation source pilot signal in the first part of the pilot signal; using the joint pilot signal of the multi-antenna backscattering tag and the environmental excitation source, the channel of the cascaded backscattering link corresponding to different active antenna combinations is sequentially estimated. S32: Detect the excitation signal based on the estimated decoupling channel, and then detect the backscattered signal of the multi-dimensional mapping based on the signal characteristics between links.

5. The multi-antenna backscatter communication method as described in claim 4, characterized in that, S32 includes: first estimating the excitation signal based on the maximum likelihood principle according to the signal characteristics between links, and then combining the estimated channel of the direct link to eliminate interference to the direct link in the received signal of the receiver, thereby realizing the joint detection of multi-antenna tags in index and spatiotemporal dimension information.

6. A multi-antenna backscatter communication device, characterized in that, A method for performing the multi-antenna backscatter communication method according to any one of claims 1-5, comprising: An environmental excitation source is used to transmit excitation signals; A multi-antenna backscattering tag is used to reflect the excitation signal by selecting antennas and controlling the impedance network, thereby achieving multi-dimensional mapping of tag information. The receiver is configured to decouple the coupling channels of the direct-fire link and the cascaded backscattering link based on the joint pilot signals corresponding to the multi-antenna backscattering tags and the environmental excitation source, thereby separately estimating the channels of the direct-fire link and the cascaded backscattering link; detect the excitation signal based on the estimated decoupled channels, and then detect the backscattering signal of the multi-dimensional mapping based on the signal characteristics between the links.

7. A multi-antenna backscatter communication system, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

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