Backscattering-assisted information energy multiplexing transmission system and control method thereof

Abstract

The invention discloses a backscattering-assisted information and energy multiplexing transmission system and a control method thereof, the backscattering-assisted information and energy multiplexing transmission system comprises an excitation source, an information and energy multiplexing transmission subsystem and a reader, and the excitation source transmits a carrier signal; the omnidirectional antenna captures a signal and the signal enters the rectification filter circuit through the directional coupler so that RF-DC conversion and information demodulation of the signal are realized. The information and energy multiplexing transmission subsystem controls a signal feedback switch to realize backscattering of an omnidirectional antenna and feeds back the working state of the information and energy multiplexing transmission subsystem to the excitation source, and the excitation source adjusts the emission angle of an excitation signal according to information fed back by the information and energy multiplexing transmission subsystem, changes the energy density in a radiation range and realizes adaptive input of backscattering auxiliary energy; and the information and energy multiplexing transmission subsystem controls a data transfer switch, so that signals flow to a directional antenna through a directional coupler and transmit data to a reader, the communication power consumption of the information and energy multiplexing transmission system is reduced, and the degree of freedom of deployment of the information and energy multiplexing transmission system in a complex environment is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of signal-energy multiplexing transmission, and in particular to a backscatter-assisted signal-energy multiplexing transmission system and a control method thereof. Background Art

[0002] Passive IoT and signal-to-energy multiplexing transmission are important branches of modern IoT technology, promoting the energy efficiency and convenience of smart devices. Passive IoT refers to the transmission of energy and data wirelessly, allowing devices to work without a built-in power supply. This technology is widely used in smart homes, industrial automation, medical monitoring and other fields. By integrating wireless energy harvesting and communication into one system, passive IoT devices can operate stably for a long time without the need to replace batteries or connect power cords, greatly improving the service life and deployment flexibility of the equipment. Signal-to-energy multiplexing transmission technology is one of the core technologies of passive IoT. Its principle is to embed energy in wireless communication signals so that the receiving device can obtain the required energy while receiving data. A typical signal-to-energy multiplexing transmission system includes an energy transmitter, an energy collector and a communication module. The energy transmitter is usually a wireless charger or base station that transmits high-frequency electromagnetic waves or radio frequency signals; the energy collector is an energy harvesting module integrated in the device, which is responsible for converting the received electromagnetic waves or radio frequency signals into electrical energy; the communication module is responsible for sending and receiving data.

[0003] However, passive IoT and signal-energy multiplexing transmission technology face the challenge of high power consumption in practical applications. First, low energy transmission efficiency is a major bottleneck. Although modern technology has been able to achieve wireless energy transmission within a certain distance, the energy loss is still large, especially when the energy transmission distance is long and the channel environment is harsh, it is affected by obstacle impedance, multipath loss, etc., making the energy loss more obvious. Secondly, the signal-energy multiplexing transmission system will also generate additional energy consumption during the data transmission process. In order to ensure the stability and reliability of data transmission, the signal-energy multiplexing transmission system nodes need to continuously perform data encoding, modulation, demodulation and other operations to complete data communication with the core base station, and these operations will consume a certain amount of energy. Especially in the case of high-speed data transmission and long-term working, this energy consumption is more obvious. In the face of these problems, backscattering technology can provide a low-power, stable and reliable solution for the passive IoT.

[0004] Backscatter Communication is a low-power wireless communication technology that achieves data transmission by reflecting and modulating existing radio signals in the environment. This technology does not require a separate transmitter and power supply, but instead uses wireless signals in the environment, such as TV, Wi-Fi or mobile phone signals, to reflect them back to the receiver to transmit information. Backscatter devices usually consist of an antenna and a simple modulation circuit, which encodes data by changing the phase or amplitude of the reflected signal. Due to its extremely low power consumption, backscatter technology is widely used in IoT devices, RFID tags, sensor networks and other fields, helping to achieve long-term operation and battery-free operation;

[0005] At the same time, in the face of harsh and complex working environments, if the tag antenna is an omnidirectional antenna, it can receive RF signals from all directions and collect energy efficiently. However, due to the reciprocity of the antenna, the signal is evenly reflected to the surroundings, which may cause reading failure or long reading time. Although the adaptive adjustment of the excitation source can still work normally, it has a greater impact on the work of the reader. If the tag antenna is a directional antenna, it is difficult to receive enough signals from the environment for forwarding and self-powering. Therefore, the traditional tag antenna cannot be directly applied to environmental backscattering. The dual-antenna structure method is adopted to enable the tag to have both energy storage and forwarding functions, so as to achieve full coverage of the signal in complex areas. Summary of the invention

[0006] In order to overcome the defects and shortcomings of the prior art, the present invention provides a backscatter-assisted signal-energy multiplexing transmission system, which can realize low-power and low-cost communication of passive Internet of Things nodes, and ensure that the nodes can stably and efficiently obtain the energy of radio frequency signals in harsh and complex environments.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention provides a backscatter-assisted signal-energy multiplexing transmission system, comprising: an excitation source, a signal-energy multiplexing transmission subsystem and a reader;

[0009] The excitation source is used to transmit a carrier signal that carries energy and is not modulated, and adjust the radiation angle of the transmitted signal;

[0010] The signal-energy multiplexing transmission subsystem includes an omnidirectional antenna, a signal feedback switch, a directional coupler, a data transfer switch, a rectifier filter circuit, an energy manager, a signal demodulation module, a micro control unit, a sensor module and a directional antenna;

[0011] The omnidirectional antenna is used to obtain a carrier signal, and the micro control unit is used to control the closing and opening of a signal feedback switch to change the absorption or reflection state of the omnidirectional antenna to the incident signal;

[0012] The micro control unit is used to control the closing and opening of the data transmission switch, and change the absorption or reflection state of the signal at the output end of the directional coupler by the rectification and filtering circuit;

[0013] When the signal feedback switch is closed, the directional coupler input end receives the signal obtained by the omnidirectional antenna and transmits the signal directionally to the directional coupler output end. When the data transmission switch is open, the input signal is transmitted to the coupling end of the directional coupler and then to the directional antenna.

[0014] The rectifier and filter circuit is used to perform RF-DC conversion on the received signal, output a DC voltage to the energy manager, and transmit part of the DC signal to the signal demodulation module;

[0015] The energy manager is used to perform step-up conversion on the DC voltage and transmit the power storage status to the micro control unit;

[0016] The signal demodulation module is used to perform signal demodulation and output the demodulation result to the micro control unit;

[0017] The micro control unit is used to obtain the collected information of the sensor module, and control the signal feedback switch and the closing and opening of the data transmission switch according to the demodulation result;

[0018] The reader obtains the transmission signal of the directional antenna and the collection information obtained by the sensor module in the signal-energy multiplexing transmission subsystem.

[0019] As a preferred technical solution, the excitation source includes a base station, a transmitting antenna and a receiving antenna, and the base station is connected to the transmitting antenna and the receiving antenna respectively;

[0020] The base station is used to generate a carrier signal that carries energy and is not modulated, the transmitting antenna is used to transmit the carrier signal to free space, and the receiving antenna is used to receive a signal backscattered by the omnidirectional antenna.

[0021] As a preferred technical solution, the polarization modes of the transmitting antenna and the receiving antenna are both circular polarization, and the polarization modes of the transmitting antenna and the receiving antenna are orthogonal to each other.

[0022] As a preferred technical solution, the polarization mode of the omnidirectional antenna is circular polarization, and the polarization modes of the omnidirectional antenna and the receiving antenna are orthogonal to each other. When the omnidirectional antenna reflects the signal of the transmitting antenna through backscattering, the polarization mode of the reflected signal matches the polarization mode of the receiving antenna.

[0023] As a preferred technical solution, the signal feedback switch includes: field effect transistor FET1, field effect transistor FET2 and an inverter, as well as a power supply VDD interface, a ground GND interface, a control signal input interface, a radio frequency signal input interface and a radio frequency signal output interface;

[0024] The micro control unit is connected to the control signal input interface, the control signal input interface is connected to the gate of the field effect transistor FET1 through an inverter, and the source and drain of the field effect transistor FET1 are respectively connected to the radio frequency signal input interface and the radio frequency signal output interface;

[0025] The control signal input interface is connected to the gate of the field effect transistor FET2, and the source and drain of the field effect transistor FET2 are connected to the ground GND interface and the radio frequency signal output interface respectively;

[0026] The inverter is provided with two field effect transistors, wherein the drain of one field effect transistor is connected to the power supply VDD interface;

[0027] When the control signal input interface is at a high level, the field effect tube FET2 is turned on, the field effect tube FET1 is turned off, presenting a high impedance state, and the signal feedback switch is in an open circuit state;

[0028] When the control signal input interface is at a low level, the field effect transistor FET2 is turned off, the field effect transistor FET1 is turned on, and the signal feedback switch is in a closed state.

[0029] As a preferred technical solution, the directional coupler adopts a three-port coupler, which is composed of four arms forming a square structure, and the four arms are all quarter-wavelength lines of the operating frequency.

[0030] As a preferred technical solution, the rectification and filtering circuit includes a bandpass filter, a harmonic suppressor, a radio frequency rectifier and a low-pass filter. The bandpass filter is used to filter out the frequency band signal, the radio frequency rectifier rectifies the bandpass filter output signal into a DC signal, the harmonic suppressor is used to suppress higher harmonics, and the low-pass filter is used to remove high-frequency components and retain low-frequency signals.

[0031] As a preferred technical solution, the sensor module of the signal-energy multiplexing transmission subsystem adopts one or more of a temperature sensor, a humidity sensor, and a light sensor.

[0032] As a preferred technical solution, the reader includes a reader antenna and a central processing unit. The reader antenna is used to obtain the signal transmitted by the directional antenna of the signal energy multiplexing transmission subsystem, and the central processing unit is used to demodulate the signal obtained by the reader antenna to obtain the collection information of the sensor module of the signal energy multiplexing transmission subsystem.

[0033] The present invention also provides a control method for a backscatter-assisted signal-energy multiplexing transmission system, comprising the following steps:

[0034] The excitation source transmits a carrier signal that carries energy and is not modulated, and adjusts the radiation angle of the transmitted signal;

[0035] The signal multiplexing transmission subsystem obtains the carrier signal, and when the signal demodulation module demodulates and obtains the set prefix, the demodulation result is transmitted to the micro control unit;

[0036] When the micro control unit determines that the demodulation result is a query signal, the signal feedback switch is controlled to perform backscattering, and when the demodulation result does not contain a set prefix, the data transmission switch is controlled to close;

[0037] When the micro control unit inquires through the energy manager that the current stored power reaches the set threshold, it controls the data transmission switch to be disconnected and transmits data to the reader.

[0038] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0039] (1) The signal-energy multiplexing transmission subsystem of the present invention can be charged over a long distance without the need to install or replace batteries, and has low power consumption during operation and is easy to integrate with a variety of sensors, and can complete a variety of passive Internet of Things tasks.

[0040] (2) The signal-energy multiplexing transmission subsystem of the present invention utilizes backscattering auxiliary nodes to complete the communication with the excitation source and the reader. When communicating, the signal-energy multiplexing transmission subsystem only needs to control the closing and opening of the corresponding switches without completing operations such as modulation, which greatly reduces the power consumption of the communication process.

[0041] (3) The signal-energy multiplexing transmission node of the present invention is a dual-antenna system, and has a circularly polarized omnidirectional antenna to collect energy in free space, so that the overall deployment of the system is flexible and can adapt to a variety of working scenarios.

[0042] (4) In addition to collecting the signal energy emitted by the excitation source, the signal-energy multiplexing transmission subsystem of the present invention can also collect and use the signal energy collected in free space to maintain normal operation, which reduces the dependence on the excitation source to a certain extent, helps to reduce the power consumption of the excitation source, and is suitable for large-scale deployment. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the overall architecture of the backscatter-assisted signal-energy multiplexing transmission system of the present invention;

[0044] Figure 2 A schematic diagram of a large-scale multi-node cluster working scenario of a backscatter-assisted signal-energy multiplexing transmission system of the present invention;

[0045] Figure 3 A schematic diagram of the excitation source working process of the backscatter-assisted signal-energy multiplexing transmission system of the present invention;

[0046] Figure 4 A schematic diagram of the principle of the radio frequency switch circuit of the backscatter-assisted signal-energy multiplexing transmission system of the present invention;

[0047] Figure 5 A schematic diagram of the principle of a directional coupler circuit of a backscatter-assisted signal-energy multiplexing transmission system of the present invention;

[0048] Figure 6 The figure is a schematic diagram of the backscattering workflow of the signal-energy multiplexing transmission subsystem of the backscatter-assisted signal-energy multiplexing transmission system of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0050] Example

[0051] like Figure 1 As shown, this embodiment provides a backscatter-assisted signal multiplexing transmission system, including: an excitation source, a signal multiplexing transmission subsystem and a reader;

[0052] In this embodiment, the excitation source includes a base station, a transmitting antenna and a receiving antenna, wherein the base station generates a simple carrier signal carrying energy and not modulated, and transmits it to free space by the transmitting antenna, and is captured by the omnidirectional antenna of the signal-energy multiplexing transmission subsystem. The polarization modes of the transmitting antenna and the receiving antenna of the excitation source are both circular polarization, but the polarization modes of the transmitting antenna and the receiving antenna are orthogonal to each other, thereby avoiding crosstalk caused by sharing channels in space, and the circularly polarized backscattered signal can reduce the impact of multipath fading, thereby improving the fault tolerance and stability of the system.

[0053] like Figure 2 As shown, each excitation source transmits a simple carrier signal carrying energy into free space, and any signal-energy multiplexing transmission subsystem can capture these signals, and each excitation source can provide energy to multiple signal-energy multiplexing transmission subsystems at the same time.

[0054] like Figure 3As shown, the excitation source continuously transmits a simple carrier signal carrying energy into the free space to provide energy for the signal-energy multiplexing transmission subsystems within the range; after continuous transmission for a period of time g1, the excitation source modulates the inquiry information in the carrier to query the energy status and signal strength of each signal-energy multiplexing transmission subsystem within the range; during the waiting reply period g2, the backscattered reply demodulation of the signal-energy multiplexing transmission subsystem is collected, and then the energy status of each signal-energy multiplexing transmission subsystem and the received energy signal strength are comprehensively evaluated. If a node is found to be in a state of insufficient energy supply, the radiation angle of the transmitted signal will be adjusted according to actual needs or the transmission power will be adjusted if necessary, so that the signal can better cover the node. During this period, the excitation source will continue to send carrier signals to charge the node.

[0055] In this embodiment, the signal-energy multiplexing transmission subsystem includes an omnidirectional antenna, a signal feedback switch, a directional coupler, a data transfer switch, a rectifier filter circuit, an energy manager, a signal demodulation module, a sensor module, a micro control unit and a directional antenna;

[0056] The excitation source transmits a simple carrier signal with energy, which is transmitted to the signal-energy multiplexing transmission subsystem through free space; the signal is captured by the omnidirectional antenna of the signal-energy multiplexing transmission subsystem, and enters the rectifier filter circuit through the directional coupler, realizing the RF-DC conversion and information demodulation of the input signal; the signal-energy multiplexing transmission subsystem realizes the backscattering of the omnidirectional antenna by controlling the signal feedback switch, thereby feeding back its own related working status to the excitation source. After receiving the information fed back by the signal-energy multiplexing transmission subsystem, the excitation source can adjust the emission angle of the excitation signal according to actual needs to change the energy density within the radiation range, thereby realizing backscattering auxiliary energy adaptive input; at the same time, the sensor of the signal-energy multiplexing transmission subsystem can collect the required parameters, and control the data transmission switch through the signal-energy multiplexing transmission subsystem, so that the signal flows to the directional antenna through the directional coupler, and the directional antenna transmits data to the reader, and finally the reader obtains the data of the sensor, thereby reducing the power consumption of the communication of the signal-energy multiplexing transmission system and improving the degree of freedom of deployment of the signal-energy multiplexing transmission system in complex environments;

[0057] In this embodiment, the polarization mode of the omnidirectional antenna is circular polarization, which is the same as the transmitting antenna of the excitation source, so that the signal transmitted by the transmitting antenna can be captured in free space. At the same time, the circular polarization signal reduces the energy loss caused by multipath interference and polarization angle mismatch, and maximizes the received energy.

[0058] The polarization modes of the receiving antenna and the omnidirectional antenna are orthogonal to each other. When the omnidirectional antenna reflects the signal from the transmitting antenna through backscattering, the polarization mode of the reflected signal matches the polarization mode of the receiving antenna, so the signal backscattered by the omnidirectional antenna can be received.

[0059] The omnidirectional antenna has a wider radiation angle, so it can receive a wider incident angle, ensuring that the omnidirectional antenna can still receive the signal of the transmitting antenna when the transmitting antenna of the excitation source is not precisely aligned, thereby improving the fault tolerance and stability of the system;

[0060] At the same time, the omnidirectional antenna can also receive other radio frequency signals within a wide angle range and use them as additional energy supplement after rectification and filtering.

[0061] The signal feedback switch is a radio frequency switch composed of lumped components such as transistors, resistors, and capacitors, and contains power supply VDD, ground GND, control signal input V CTRL , RF signal input RF IN And RF signal output RF OUT Five interfaces;

[0062] like Figure 4 As shown, the RF switch is based on two field effect transistors FET1 and FET2 and an inverter NG composed of two field effect transistors; when V CTRL When it is high level, FET2 is turned on, and FET1 is turned off under the action of inverter NG, presenting a high impedance state. At this time, the RF switch is in an open circuit state, that is, the switch is disconnected; when V CTRL When it is low level, FET2 is turned off, and FET1 is turned on by the inverter NG, so that RF IN The signal can be smoothly output to RF OUT ,At this time, the RF switch is in the on state, that is, the switch is closed.

[0063] When the signal feedback switch is working normally, the high and low levels of the control signal determine whether the two interfaces of the RF signal input and RF signal output are connected. When the control signal is at a high level, the switch is disconnected, and when the control signal is at a low level, the switch is closed. The control signal is sent by the micro control unit;

[0064] When the signal feedback switch is closed, the signal can flow from the omnidirectional antenna to the directional coupler, and the omnidirectional antenna absorbs the incident signal. When the signal feedback switch is open, the signal cannot enter the signal multiplexing transmission subsystem from the omnidirectional antenna, and the omnidirectional antenna reflects the incident signal.

[0065] By controlling the closing and opening of the signal feedback switch, the absorption or reflection state of the incident signal by the omnidirectional antenna can be changed, so that backscattering can be used to communicate with the excitation source, and a specific coding method can be used to control the omnidirectional antenna to feedback information to the receiving antenna;

[0066] When the signal feedback switch is closed when the control signal is at a low level, the signal can flow from the omnidirectional antenna to the directional coupler, completing the signal energy RF-DC conversion and providing energy for the signal-energy multiplexing transmission subsystem. At the same time, it also reduces unnecessary power consumption of the signal feedback switch during charging and improves the system's endurance.

[0067] In this embodiment, the specific encoding method includes but is not limited to ASK, FSK, and PSK, which can be determined by the actual circuit design;

[0068] The directional coupler is a three-port coupler. The three interfaces are input, output and coupling according to their functions. The omnidirectional antenna and the signal feedback switch are connected in sequence and connected to the input. The output is connected to the rectifier filter circuit through the data transfer switch, and the coupling is connected to the directional antenna.

[0069] like Figure 5 As shown in the figure, the core part of the directional coupler circuit is a square structure composed of four arms, and three ports and a ground port are led out at the apex of the square structure, which is the same as the branch line coupler with the isolation end grounded. The three ports are denoted as ①, ②, and ③, respectively. Port ① is the input end, port ② is the output end, and port ③ is the coupling end. The four arms of the directional coupler circuit are all quarter-wavelength (90°) lines of the operating frequency, and the characteristic impedances are 50Ω, 25Ω, 50Ω, and 25Ω, respectively, where n is an integer; ideally, the incident wave a1 is directional coupled from the input end, and when charged, the signal b2 flows from the input end to the output end, and the signal b3 flows to the isolation end. Since the output end is matched and the isolation end is grounded and short-circuited, only the isolation end generates the reflected signal a3, and part of the signal b4 is reflected to the coupling end, and there is:

[0070]

[0071] It can be seen that at this time, the output of the coupling end is only the output end When the output end is disconnected, the output end and the isolation end t are totally reflected at the same time, then:

[0072]

[0073] It can be seen that the input end is completely matched at this time, no reflected signal passes through, and all incident signals flow to the coupling end.

[0074] When the signal feedback switch of the directional coupler is closed, the input end of the directional coupler receives the signal captured by the omnidirectional antenna and transmits the signal directionally to the output end;

[0075] When the output end is an open load, the input and output impedances at the output end are not matched, the input signal will be reflected at the output end, and will be transmitted directionally to the coupling end in the directional coupler, and finally the signal will flow to the directional antenna.

[0076] The data transmission switch is the same as the signal feedback switch, which is an RF switch and also has five interfaces: power supply VDD, ground GND, control signal input, RF signal input and RF signal output;

[0077] When the data transfer switch is working normally, whether it is disconnected is determined by the level of the control signal, and the control signal is sent by the micro control unit;

[0078] When the control signal is at a low level, the switch is closed, the input and output impedances of the directional coupler output end are well matched, and the rectifier filter circuit absorbs the signal at the output end. The signal flows to the rectifier filter circuit through the directional coupler, completing the received signal and performing RF-DC conversion.

[0079] When the control signal is at a high level, the switch is disconnected, the output end of the directional coupler is open, and the rectifier and filter circuit reflects the signal at the output end. The signal is reflected at the output end to the coupling end of the directional coupler and transmitted from the directional antenna to the free space.

[0080] When the data transfer switch is closed, the signal flows to the rectifier and filter circuit, ensuring low power consumption of the system during normal operation and improving the endurance of the system.

[0081] The data transfer switch changes the state of absorption or reflection of the signal by changing the closed and open states, thereby using a specific coding method to modulate the incident signal received by the omnidirectional antenna and transmit it through the directional antenna, reducing the power consumption of the signal multiplexing transmission subsystem in sending messages to the reader.

[0082] The rectifier and filter circuit includes a bandpass filter, a harmonic suppressor, a radio frequency rectifier and a low-pass filter; when the signal feedback switch and the data transmission switch are closed, the signal received by the omnidirectional antenna will flow through the signal feedback switch and the directional coupler in sequence. When the signal enters the rectifier and filter circuit, the input signal is filtered out by the bandpass filter to remove signals of other frequency bands. The signal is then rectified into a DC signal in the radio frequency rectifier circuit. The high-order harmonics generated by the diode in the rectifier circuit will be repeatedly reflected between the harmonic suppressor and the low-pass filter and gradually rectified into a DC signal by the radio frequency rectifier, thereby maximizing the rectifier signal energy. Finally, the AC signal becomes a smooth DC voltage to be supplied to the subsequent energy manager or information demodulation circuit.

[0083] The energy manager can boost the DC voltage output by the rectifier filter circuit to a stable voltage output, and use the output voltage to charge the capacitor inside the energy manager. At the same time, it monitors the energy status of its own storage in real time and transmits the power storage status to the micro control unit.

[0084] The signal demodulation module can utilize part of the output of the rectifier and filter circuit to demodulate the signal. If a specific prefix is ​​found in the demodulation result, the demodulation result is sent to the micro control unit.

[0085] The sensor module can freely select specific modules according to the needs of the working scene, including but not limited to temperature, humidity, light and other sensors. The sensor module uses the energy collected by the signal-energy multiplexing transmission subsystem in free space to maintain normal operation and transmit the obtained data to the micro control unit for storage;

[0086] The micro control unit will periodically query the current power status. If the set threshold Q is reached, it will control the data transmission switch. During control, the data will be modulated onto the signal according to the encoding method used, so as to transmit the data obtained by the sensor to the reader.

[0087] The directional antenna has a narrow beam angle and concentrated radiation energy, and has a long communication distance while radiating in a directional manner;

[0088] The signal multiplexing transmission subsystem composed of directional antenna and omnidirectional antenna is a dual-antenna system. The system is relatively free in location deployment and will not affect the alignment of the directional antenna and the reader.

[0089] In this embodiment, the reader includes a reader antenna and a central processing unit;

[0090] After capturing the signal emitted by the directional antenna of the signal multiplexing transmission subsystem into free space, the reader antenna transmits the signal to the central processor for demodulation, thereby obtaining relevant information obtained by the sensor module in the signal multiplexing transmission subsystem.

[0091] like Figure 6 As shown, when the signal-energy multiplexing transmission subsystem captures the RF signal in free space, since each switch is in a closed state by default, the signal will pass through the rectification and filtering circuit and become a relatively smooth DC signal, wherein part of the output DC signal is sent to the signal demodulation module by the power division circuit to demodulate the signal; when the demodulation finds that the received signal has a specific prefix, the demodulation result will be notified to the micro control unit, which will make a judgment. If the judgment finds that the demodulation result is a query signal, the signal feedback switch will be controlled to perform backscattering, otherwise the corresponding instruction will be executed; if the demodulation result does not contain a specific prefix, it means that the signal does not contain information from the excitation source, and the subsystem node continues to perform rectification, filtering and charging operations, and stores the obtained DC signal in the capacitor after boosting through the energy manager; when the micro control unit inquires through the energy manager that the current stored power reaches the set threshold value Q, it will suspend the charging operation and start transmitting data to the reader instead.

[0092] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A backscatter-assisted signal-energy multiplexing transmission system, characterized in that: include: Excitation source, signal multiplexing transmission subsystem and reader; The excitation source is used to transmit a carrier signal that carries energy and is not modulated, and adjust the radiation angle of the transmitted signal; The signal-energy multiplexing transmission subsystem includes an omnidirectional antenna, a signal feedback switch, a directional coupler, a data transfer switch, a rectifier filter circuit, an energy manager, a signal demodulation module, a micro control unit, a sensor module and a directional antenna; The omnidirectional antenna is used to obtain a carrier signal, and the micro control unit is used to control the closing and opening of a signal feedback switch to change the absorption or reflection state of the omnidirectional antenna to the incident signal; The micro control unit is used to control the closing and opening of the data transmission switch, and change the absorption or reflection state of the signal at the output end of the directional coupler by the rectification and filtering circuit; When the signal feedback switch is closed, the directional coupler input end receives the signal obtained by the omnidirectional antenna and transmits the signal directionally to the directional coupler output end. When the data transmission switch is open, the input signal is transmitted to the coupling end of the directional coupler and then to the directional antenna. The rectifier and filter circuit is used to perform RF-DC conversion on the received signal, output a DC voltage to the energy manager, and transmit part of the DC signal to the signal demodulation module; The energy manager is used to perform step-up conversion on the DC voltage and transmit the power storage status to the micro control unit; The signal demodulation module is used to perform signal demodulation and output the demodulation result to the micro control unit; The micro control unit is used to obtain the collected information of the sensor module, and control the signal feedback switch and the closing and opening of the data transmission switch according to the demodulation result; The reader obtains the transmission signal of the directional antenna and the collection information obtained by the sensor module in the signal-energy multiplexing transmission subsystem.

2. The backscatter-assisted signal-energy multiplexing transmission system according to claim 1, characterized in that: The excitation source includes a base station, a transmitting antenna and a receiving antenna, and the base station is connected to the transmitting antenna and the receiving antenna respectively; The base station is used to generate a carrier signal that carries energy and is not modulated, the transmitting antenna is used to transmit the carrier signal to free space, and the receiving antenna is used to receive a signal backscattered by the omnidirectional antenna.

3. The backscatter-assisted signal-energy multiplexing transmission system according to claim 2, characterized in that: The polarization modes of the transmitting antenna and the receiving antenna are both circular polarization, and the polarization modes of the transmitting antenna and the receiving antenna are orthogonal to each other.

4. The backscatter-assisted signal-energy multiplexing transmission system according to claim 2, characterized in that: The polarization mode of the omnidirectional antenna is circular polarization. The polarization modes of the omnidirectional antenna and the receiving antenna are orthogonal to each other. When the omnidirectional antenna reflects the signal of the transmitting antenna through backscattering, the polarization mode of the reflected signal matches the polarization mode of the receiving antenna.

5. The backscatter-assisted signal-energy multiplexing transmission system according to claim 1, characterized in that: The signal feedback switch includes: a field effect transistor FET1, a field effect transistor FET2 and an inverter, as well as a power supply VDD interface, a ground GND interface, a control signal input interface, a radio frequency signal input interface and a radio frequency signal output interface; The micro control unit is connected to the control signal input interface, the control signal input interface is connected to the gate of the field effect transistor FET1 through an inverter, and the source and drain of the field effect transistor FET1 are respectively connected to the radio frequency signal input interface and the radio frequency signal output interface; The control signal input interface is connected to the gate of the field effect transistor FET2, and the source and drain of the field effect transistor FET2 are connected to the ground GND interface and the radio frequency signal output interface respectively; The inverter is provided with two field effect transistors, wherein the drain of one field effect transistor is connected to the power supply VDD interface; When the control signal input interface is at a high level, the field effect tube FET2 is turned on, the field effect tube FET1 is turned off, presenting a high impedance state, and the signal feedback switch is in an open circuit state; When the control signal input interface is at a low level, the field effect transistor FET2 is turned off, the field effect transistor FET1 is turned on, and the signal feedback switch is in a closed state.

6. The backscatter-assisted signal-energy multiplexing transmission system according to claim 1, characterized in that: The directional coupler adopts a three-port coupler, which is composed of four arms forming a square structure, and the four arms are all quarter-wavelength lines of the working frequency.

7. The backscatter-assisted signal-energy multiplexing transmission system according to claim 1, characterized in that: The rectification and filtering circuit includes a bandpass filter, a harmonic suppressor, a radio frequency rectifier and a low-pass filter. The bandpass filter is used to filter out the frequency band signal. The radio frequency rectifier rectifies the bandpass filter output signal into a DC signal. The harmonic suppressor is used to suppress high-order harmonics. The low-pass filter is used to remove high-frequency components and retain low-frequency signals.

8. The backscatter-assisted signal-energy multiplexing transmission system according to claim 1, characterized in that: The sensor module of the signal-energy multiplexing transmission subsystem adopts one or more of a temperature sensor, a humidity sensor, and a light sensor.

9. The backscatter-assisted signal-energy multiplexing transmission system according to claim 1, characterized in that: The reader includes a reader antenna and a central processing unit. The reader antenna is used to obtain the directional antenna transmission signal of the signal energy multiplexing transmission subsystem. The central processing unit is used to demodulate the signal obtained by the reader antenna to obtain the collection information of the sensor module of the signal energy multiplexing transmission subsystem.

10. The control method of the backscatter-assisted signal-energy multiplexing transmission system according to any one of claims 1 to 9, characterized in that: The steps include: The excitation source transmits a carrier signal that carries energy and is not modulated, and adjusts the radiation angle of the transmitted signal; The signal multiplexing transmission subsystem obtains the carrier signal, and when the signal demodulation module demodulates and obtains the set prefix, the demodulation result is transmitted to the micro control unit; When the micro control unit determines that the demodulation result is a query signal, the signal feedback switch is controlled to perform backscattering, and when the demodulation result does not contain a set prefix, the data transmission switch is controlled to close; When the micro control unit inquires through the energy manager that the current stored power reaches the set threshold, it controls the data transmission switch to be disconnected and transmits data to the reader.

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