Green Backscatter Communication System Based on Flexible Modulator

Abstract

This invention discloses a green backscatter communication system based on a flexible modulator, comprising a flexible modulator and a novel information reception and demodulation method established through software-defined radio technology. The transmitting device sends a single-tone signal to the flexible modulation module, which integrates a transparent flexible array antenna and a hybrid energy harvesting module. The receiving end introduces an m-sequence as a frame header identification code and performs dual-path parallel processing on the signal. The communication system is verified using a novel information reception and demodulation method, enabling text, image, and video transmission. The modulation end has a simple structure, small size, and extremely low power consumption. Hybrid energy harvesting can meet the system's power consumption requirements, making it green, environmentally friendly, and sustainable, offering significant advantages for large-scale deployment and subsequent maintenance. The receiver's software-defined reception and processing system adopts a standardized and modular structure, enabling the implementation of traditional hardware functions through software, covering multiple modes and frequency bands with strong openness.

Description

Technical Field

[0001] This invention relates to the fields of microwave device technology and communication engineering, specifically to a green backscatter communication transmission system based on a flexible modulator, and more particularly to an information transmission system that does not require active electromagnetic wave radiation for passive communication. Background Technology

[0002] Existing traditional communication systems suffer from significant limitations in miniaturization, packaging, and mass production costs due to the presence of complex circuitry such as signal generation amplifiers. Furthermore, most traditional communication systems consume power in the watt range, posing considerable inconvenience for long-term battery life and maintenance during large-scale deployments. Therefore, a novel communication technology that eliminates the need for active electromagnetic wave radiation—backscattering systems—has attracted considerable attention due to its low power consumption, small size, and ease of large-scale deployment. It simplifies the traditional radio frequency front-end to a single transistor switch, minimizing manufacturing costs and energy requirements.

[0003] The application of most existing communication devices is limited to some extent by their power supply modules. Furthermore, complex wiring during large-scale deployment not only increases the difficulty of deployment but also hinders subsequent maintenance and upgrades. Therefore, a self-powered communication system is becoming a new trend in IoT applications. Solar energy, as a green and clean renewable energy source, is widely used in various power supply circuit systems.

[0004] Traditional flexible transparent antenna material ITO suffers from low conductivity and high sheet resistance, resulting in low efficiency and failure to achieve the designed gain in finished antennas. Backscatter communication, which receives external radiated waves as carrier waves instead of actively generating electromagnetic waves, inherently has limited signal strength. Using traditional materials and processes would severely restrict the communication distance of the system. Therefore, a flexible array antenna fabricated using an extremely fine transparent metal mesh offers advantages such as high conductivity, low sheet resistance, high efficiency, and high gain. Summary of the Invention

[0005] Technical Problem: In view of the above-mentioned shortcomings of the prior art, the purpose of this invention is to provide a green backscatter communication system based on a flexible modulator, which is not only simple in structure and small in size, but also has a single-chip microcomputer power consumption of less than 1mw, a single PIN tube power consumption at the microwatt level, and a transparent flexible array antenna with a transparent mesh metal wire sheet resistance as low as 0.1Ω / sq.

[0006] Technical solution: To achieve the above-mentioned objectives, the present invention provides a green backscatter communication system based on a flexible modulator, comprising: a transmitting device, a flexible modulation module, a transparent flexible array antenna, a hybrid energy harvesting module, a microcontroller encoding module, a power management module, a receiving module, and software radio;

[0007] The transmitting device sends a single-tone signal to the flexible modulation module, which integrates a transparent flexible array antenna and a hybrid energy harvesting module. The energy harvesting and information transmission states are switched through a microcontroller encoding module, enabling the flexible modulation module to achieve self-powered green communication. The receiving module introduces an m-sequence as an information frame header identification code through software radio and performs dual-path parallel processing on the modulated signal. The flexible modulation module does not need to generate a high-frequency carrier signal itself, but instead passively uses the single-tone signal from the transmitting device to generate a modulated signal to achieve green backscatter communication.

[0008] The transparent flexible array antenna adopts a transparent metal mesh structure, which is composed of extremely fine metal wires. The transparent metal mesh structure has high electrical conductivity and low sheet resistance, high efficiency and gain, and high light transmittance.

[0009] The transparent flexible array antenna uses a microcontroller encoding module to control the switch connected to the antenna based on the information collected, thereby enabling the transparent flexible array antenna to switch between two working states: radio frequency energy collection and information transmission at different time points T1 and T2.

[0010] The transparent flexible array antenna and the hybrid energy harvesting module are integrated into one unit and bonded together, enabling hybrid energy harvesting and information transmission of solar radio frequency energy on a single board surface;

[0011] In the hybrid energy harvesting state, the transparent flexible array antenna receives high-frequency electromagnetic energy from the environment and converts it into a DC signal through a flexible rectifier circuit; the solar panel in the hybrid energy harvesting module receives light energy and converts it into a DC signal; the high-frequency electromagnetic energy and the DC signal converted from solar energy are regulated and output through the energy harvester ADP5091 and stored in the supercapacitor of the energy storage unit to provide stable energy for the subsequent modulator operation;

[0012] In the information transmission state, the microcontroller encoding module stores the encoded baseband signal. After being activated by the 3.3V voltage regulation provided by the hybrid energy harvesting module, it outputs high and low levels carrying the baseband signal to the PIN diode on the transparent flexible array antenna, thereby controlling the on and off state of the PIN diode. After the single-tone signal generated by the transmitting device is loaded onto the array antenna, the single-tone signal is modulated because the PIN diode in the on and off states responds differently to the single-tone signal, and is transmitted to the receiving and processing device by backscattering.

[0013] The receiving module uses software radio to capture the reflected modulated signal. It first demodulates the captured signal using binary phase-shift keying (BPSK) to separate the baseband and carrier signals. The resulting separated baseband signal is then passed through a matched filter and sent to the clock synchronization module. This clock synchronization module can perform the functions of an interpolation filter, an interpolation differential filter, a timing error detector (TED), and a proportional-integral loop filter. It estimates and tracks the symbol rate, i.e., the number of samples per symbol, providing an initial estimate for each symbol sample and the allowable deviation from that estimate. It performs the required timing synchronization, sampling the signal at the correct time point to complete the clock synchronization signal at the transceiver end.

[0014] The clock synchronization signal is converted into a 0 / 1 digital signal by a decision unit with a threshold of 0. Due to the uncertainty of the relative position between the receiver and the backscatter array antenna, the received phase is uncertain. The 0 / 1 digital signal is processed in parallel with two parallel bipolar signals. One is to multiply the 0 / 1 digital signal by -2 and add 1, setting 0 to 1 and 1 to -1; the other is to multiply the 0 / 1 digital signal by 2 and subtract 1, setting 0 to -1 and 1 to 1, thus obtaining a -1 / 1 bipolar digital signal.

[0015] The bipolar digital signal is passed through a finite-length unit impulse response filter. The taps of the filter are set to an m-sequence. In this way, the autocorrelation of the input sequence and the bipolar m-sequence is tested by the filter, and the output value is judged. The judgment threshold is the number of bits in the m-sequence minus 10. If the output result is higher than this value, a valid judgment flag bit 1 / 2 is generated.

[0016] The reading module, programmed by the 0 / 1 digital signal input, uses the generated flag bit 1 / 2 as the enable interface for the information reading and processing module to read data. When the flag bit is valid, the sequence is located in the received digital signal, and the 96 / 192 bits of data following the sequence are read and loaded into a local file to restore the binary data information of the sending end. At the same time, the read data is packaged into 8-bit blocks and stored in a local file to recover the sent text / image / video.

[0017] Beneficial Effects: Compared with existing technologies, the green backscatter communication system based on a flexible modulator of this invention first receives high-frequency electromagnetic energy through a transparent flexible array antenna, and solar energy collected by a solar panel is regulated by a power management module to power the MSP430, eliminating the need for an external power supply. Then, the MSP430 converts the signal into 0 / 1 encoded high and low levels, which are loaded onto the PIN diode as a baseband signal to modulate the external radiated carrier rescattered modulated wave received by the transparent flexible array antenna. The USRP receives the modulated wave, performs down-conversion, and performs signal post-processing for synchronization and decoding in GNURadio. The entire system has a simple structure, small size, and requires no external power supply, facilitating large-scale deployment and maintenance. A self-powered system is designed at the transmitting end. An m-sequence is introduced during the encoding and conversion of transmitted information in the MSP430, serving both as frame header information identification and enhancing signal anti-interference capabilities. The traditional RF front-end is simplified to a single PIN diode, which requires extremely low power consumption, resulting in a significantly lower overall cost than traditional circuits. The fabricated transparent flexible array antenna has high conductivity, low sheet resistance, high efficiency, and high gain, enhancing the communication distance. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a green backscatter communication transmission system based on a flexible modulator;

[0019] Figure 2 This is a schematic diagram of the signal processing submodule structure of a flexible modulation module in a green backscatter communication transmission system based on a flexible modulator.

[0020] Figure 3 This is a schematic diagram of a hybrid energy harvesting module structure for a green backscatter communication transmission system based on a flexible modulator;

[0021] Figure 4 This is a flowchart of the receiving module of a green backscatter communication transmission system based on a flexible modulator;

[0022] Figure 5 This is a schematic diagram illustrating the text transmission result of a green backscatter communication transmission system based on a flexible modulator.

[0023] Figure 6 This is a schematic diagram illustrating the image transmission result of a green backscatter communication transmission system based on a flexible modulator. Detailed Implementation

[0024] To make the technical means, objectives, and functions of the present invention easier to understand, some specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0025] like Figure 1As shown, a green backscatter communication transmission system based on a flexible modulator, combined with Figure 1 The backscatter communication transmission system includes a flexible modulator, a transmitting device, and a receiving module.

[0026] The system includes: a transmitting device, a flexible modulation module, a transparent flexible array antenna, a hybrid energy harvesting module, a microcontroller encoding module, a power management module, a receiving module, and software radio;

[0027] The transmitting device sends a single-tone signal to the flexible modulation module, which integrates a transparent flexible array antenna and a hybrid energy harvesting module. The energy harvesting and information transmission states are switched through a microcontroller encoding module, enabling the flexible modulation module to achieve self-powered green communication. The receiving module introduces an m-sequence as an information frame header identification code through software radio and performs dual-path parallel processing on the modulated signal. The flexible modulation module does not need to generate a high-frequency carrier signal itself, but instead passively uses the single-tone signal from the transmitting device to generate a modulated signal to achieve green backscatter communication.

[0028] The transparent flexible array antenna adopts a transparent metal mesh structure, which is composed of extremely fine metal wires. The transparent metal mesh structure has high electrical conductivity and low sheet resistance, high efficiency and gain, and high light transmittance.

[0029] The transparent flexible array antenna uses a microcontroller encoding module to control the switch connected to the antenna based on the information collected, thereby enabling the transparent flexible array antenna to switch between two working states: radio frequency energy collection and information transmission at different time points T1 and T2.

[0030] Figure 2 The flexible modulator of the green backscatter communication transmission system based on the flexible modulator includes a power management module, a microcontroller encoding module, a transparent flexible array antenna, and a hybrid energy harvesting module.

[0031] Figure 3 The energy harvesting submodule of the flexible modulation module of the green backscatter communication transmission system based on a flexible modulator includes a transparent flexible array antenna, a flexible rectifier circuit, a solar panel integrated board, an energy harvester, and a supercapacitor.

[0032] The transparent flexible array antenna and the hybrid energy harvesting module are integrated into one unit and bonded together, enabling hybrid energy harvesting and information transmission of solar radio frequency energy on a single board surface;

[0033] In the hybrid energy harvesting state, the transparent flexible array antenna receives high-frequency electromagnetic energy from the environment and converts it into a DC signal through a flexible rectifier circuit; the solar panel in the hybrid energy harvesting module receives light energy and converts it into a DC signal; the high-frequency electromagnetic energy and the DC signal converted from solar energy are regulated and output through the energy harvester ADP5091 and stored in the supercapacitor of the energy storage unit to provide stable energy for the subsequent modulator operation;

[0034] In the information transmission state, the microcontroller encoding module stores the encoded baseband signal. After being activated by the 3.3V voltage regulation provided by the hybrid energy harvesting module, it outputs high and low levels carrying the baseband signal to the PIN diode on the transparent flexible array antenna, thereby controlling the on and off state of the PIN diode. After the single-tone signal generated by the transmitting device is loaded onto the array antenna, the single-tone signal is modulated because the PIN diode in the on and off states responds differently to the single-tone signal, and is transmitted to the receiving and processing device by backscattering.

[0035] Figure 4 The flowchart of the receiving and processing module of the green backscatter communication transmission system based on a flexible modulator shows that the post-processing system includes clock synchronization, 0 / 1 decision, decimation FIR filter, m-sequence threshold decision, and signal reading.

[0036] The receiving module uses software radio to capture the reflected modulated signal. It first demodulates the captured signal using binary phase-shift keying (BPSK) to separate the baseband and carrier signals. The resulting separated baseband signal is then passed through a matched filter and sent to the clock synchronization module. This clock synchronization module can perform the functions of an interpolation filter, an interpolation differential filter, a timing error detector (TED), and a proportional-integral loop filter. It estimates and tracks the symbol rate, i.e., the number of samples per symbol, providing an initial estimate for each symbol sample and the allowable deviation from that estimate. It performs the required timing synchronization, sampling the signal at the correct time point to complete the clock synchronization signal at the transceiver end.

[0037] Combination Figure 1 , Figure 2 , Figure 3 , Figure 4 A transparent flexible array antenna receives high-frequency electromagnetic energy, which is then rectified by a flexible rectifier circuit. A solar panel receives solar energy and converts it into a DC signal. The electromagnetic energy and the DC signal converted from solar energy are regulated and output by an AD5091 energy harvester. The transmitted information is fed high and low level signals onto a PIN diode via a microcontroller. The PIN diode controls the transparent flexible array antenna based on the converted 0 / 1 signals. The transparent flexible array antenna modulates and scatters the received carrier wave. The USRP receives the modulated wave and sends it to GNURadio for signal processing, ultimately reconstructing the transmitted information.

[0038] In the aforementioned communication system, the previously complex radio frequency front-end module at the transmitting end has been replaced by a single transistor, which receives and reflects external single-tone carrier signals, thereby greatly reducing the power consumption of the communication system, significantly reducing its complexity, and decreasing its size, making it easier for large-scale deployment.

[0039] The clock synchronization signal is converted into a 0 / 1 digital signal by a decision unit with a threshold of 0. Due to the uncertainty of the relative position between the receiver and the backscatter array antenna, the received phase is uncertain. The 0 / 1 digital signal is processed in parallel with two parallel bipolar signals. One is to multiply the 0 / 1 digital signal by -2 and add 1, setting 0 to 1 and 1 to -1; the other is to multiply the 0 / 1 digital signal by 2 and subtract 1, setting 0 to -1 and 1 to 1, thus obtaining a -1 / 1 bipolar digital signal.

[0040] The bipolar digital signal is passed through a finite-length unit impulse response filter. The taps of the filter are set to an m-sequence. In this way, the autocorrelation of the input sequence and the bipolar m-sequence is tested by the filter, and the output value is judged. The judgment threshold is the number of bits in the m-sequence minus 10. If the output result is higher than this value, a valid judgment flag bit 1 / 2 is generated.

[0041] The reading module, programmed by the 0 / 1 digital signal input, uses the generated flag bit 1 / 2 as the enable interface for the information reading and processing module to read data. When the flag bit is valid, the sequence is located in the received digital signal, and the 96 / 192 bits of data following the sequence are read and loaded into a local file to restore the binary data information of the sending end. At the same time, the read data is packaged into 8-bit blocks and stored in a local file to recover the sent text / image / video.

[0042] Figure 5 This is an embodiment of the text transmission of the present invention. It can be seen that the discrete points are determined after the 0 / 1 decision of the received signal; the peak value of the m-sequence decision of the received signal represents the valid information of each frame; and the text information recovered by the receiving end.

[0043] Figure 6 This is an embodiment of the image transmission of the present invention. You can see the discrete points after the 0 / 1 decision of the received signal; the peak value of the m-sequence decision of the received signal represents the valid information of each frame.

[0044] It can not only transmit text and images, but also send videos and restore the sent video information in the folder.

[0045] The embodiments described above are merely illustrative of the practical effects of the present invention. The selected embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described above. Clearly, many modifications and variations can be made based on the content of this specification. The embodiments selected and specifically described in this specification are intended to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention.

Claims

1. A green backscatter communication system based on a flexible modulator, characterized in that, The system includes: a transmitting device, a flexible modulation module, a transparent flexible array antenna, a hybrid energy harvesting module, a microcontroller encoding module, a power management module, a receiving module, and software radio; The transmitting device sends a single-tone signal to the flexible modulation module, which integrates a transparent flexible array antenna and a hybrid energy harvesting module. A microcontroller encoding module enables the switching between energy harvesting and information transmission states, allowing the flexible modulation module to achieve self-powered green communication. In hybrid energy harvesting mode, the transparent flexible array antenna receives high-frequency electromagnetic energy from the environment and converts it into a DC signal via a flexible rectifier circuit. The solar panel in the hybrid energy harvesting module receives solar energy and converts it into a DC signal. The high-frequency electromagnetic energy and the DC signal converted from solar energy are regulated and output through the energy harvester ADP5091 and stored in the supercapacitor of the energy storage unit, providing stable energy for the subsequent operation of the modulator. In information transmission mode, the microcontroller encoding module stores the encoded baseband signal. After being activated by the 3.3V voltage regulation provided by the hybrid energy harvesting module, it outputs high and low levels carrying the baseband signal to the PIN diode on the transparent flexible array antenna, thereby controlling the switching on and off of the PIN diode. After the single-tone signal generated by the transmitting device is loaded onto the array antenna, the single-tone signal is modulated because the PIN diode in the on and off states responds differently to the single-tone signal, and is transmitted to the receiving and processing device by backscattering. The receiving module introduces an m-sequence as an information frame header identification code via software radio, performs dual-channel parallel processing on the modulated signal, captures the reflected modulated signal, demodulates the captured signal using binary phase shift keying (BPSK), separates the baseband and carrier, and then sends the separated baseband signal through a matched filter to the clock synchronization module. The clock synchronization signal is converted into a 0 / 1 digital signal by a decision unit with a threshold of 0. Due to the uncertainty of the relative position between the receiver and the backscatter array antenna, the received phase is uncertain. The 0 / 1 digital signal is processed in parallel with two parallel bipolar signals. One is to multiply the 0 / 1 digital signal by -2 and add 1, setting 0 to 1 and 1 to -1; the other is to multiply the 0 / 1 digital signal by 2 and subtract 1, setting 0 to -1 and 1 to 1, thus obtaining a -1 / 1 bipolar digital signal. The bipolar digital signal is passed through a decimated finite-length unit impulse response filter, and the output value is judged; if the output result is higher than the judgment threshold, a valid judgment flag bit 1 / 2 is generated. The reading module, which is programmed using 0 / 1 digital signal input, also uses the generated flag bit 1 / 2 as the enable interface for reading data.

2. The green backscatter communication system based on a flexible modulator according to claim 1, characterized in that, The transparent flexible array antenna adopts a transparent metal mesh structure.

3. The green backscatter communication system based on a flexible modulator according to claim 1 or 2, characterized in that, The transparent flexible array antenna uses a microcontroller encoding module to control the switch connected to the antenna based on the information collected, thereby enabling the transparent flexible array antenna to switch between two working states: radio frequency energy collection and information transmission at different time points T1 and T2.

4. The green backscatter communication system based on a flexible modulator according to claim 3, characterized in that, The transparent flexible array antenna and the hybrid energy harvesting module are integrated into one unit and bonded together, enabling hybrid energy harvesting and information transmission of solar radio frequency energy on a single board.

5. The green backscatter communication system based on a flexible modulator according to claim 1, characterized in that, This clock synchronization module can implement the functions of interpolation filter, interpolation differential filter, timing error detector (TED), and proportional-integral loop filter. It can estimate and track the symbol rate, i.e., the number of samples per symbol, and provide an initial estimate of the sample value of each symbol and the allowable deviation from the estimate. It can perform the required timing synchronization, sample the signal at the correct time point, and complete the clock synchronization signal of the transmitting and receiving ends.

6. The green backscatter communication system based on a flexible modulator according to claim 1 or 5, characterized in that, The finite-length unit impulse response filter has its taps set to an m-sequence. This filter can then be used to test the autocorrelation between the input sequence and the bipolar m-sequence. The decision threshold is the number of bits in the m-sequence minus 10. If the output result is higher than the decision threshold, a valid decision flag bit 1 / 2 is generated.

7. The green backscatter communication system based on a flexible modulator according to claim 6, characterized in that, The reading module, programmed with 0 / 1 digital signal input, locates the sequence in the received digital signal when the flag bit is valid, and reads the 96 / 192 bits of data following the sequence into a local file to restore the binary data information of the sending end; at the same time, the read data is packaged into 8-bit blocks and stored in a local file to recover the sent text / image / video.

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