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

Abstract

This invention discloses a backscatter-assisted signal-energy multiplexing transmission system and its control method, including an excitation source, a signal-energy multiplexing transmission subsystem, and a reader. The excitation source transmits a carrier signal; an omnidirectional antenna captures the signal and enters a rectifier-filter circuit through a directional coupler to achieve RF-DC conversion and demodulation of the signal; the signal-energy multiplexing transmission subsystem controls a signal feedback switch to achieve backscattering of the omnidirectional antenna, feeding back its own operating state to the excitation source; the excitation source adjusts the transmission angle of the excitation signal according to the feedback information from the signal-energy multiplexing transmission subsystem, changing the energy density within the radiation range to achieve backscatter-assisted adaptive energy input; the signal-energy multiplexing transmission subsystem controls a data transmission switch, allowing the signal to flow through the directional coupler to the directional antenna, transmitting data to the reader. This invention reduces the power consumption of the signal-energy multiplexing transmission system and improves the flexibility of deployment in complex environments.

Description

Technical Field

[0001] This invention relates to the field of information-energy multiplexing transmission technology, specifically to a backscatter-assisted information-energy multiplexing transmission system and its control method. Background Technology

[0002] Passive IoT and energy multiplexing are important branches of modern Internet of Things (IoT) technology, driving energy efficiency and convenience in smart devices. Passive IoT refers to the wireless transmission of energy and data, enabling devices to operate without a built-in power source. This technology is widely used in smart homes, industrial automation, medical monitoring, and other fields. By integrating wireless energy harvesting and communication into a single system, passive IoT devices can operate stably for extended periods without the need for battery replacements or power cord connections, significantly improving device lifespan and deployment flexibility. Energy multiplexing is one of the core technologies of passive IoT. Its principle is to embed energy into wireless communication signals, allowing receiving devices to acquire the necessary energy while receiving data. A typical energy multiplexing system includes an energy transmitter, an energy harvester, and a communication module. The energy transmitter is usually a wireless charger or base station that emits high-frequency electromagnetic waves or radio frequency signals; the energy harvester is an energy harvesting module integrated into the device, responsible for converting the received electromagnetic waves or radio frequency signals into electrical energy; and the communication module is responsible for data transmission and reception.

[0003] However, passive IoT and energy multiplexing transmission technologies face the challenge of high power consumption in practical applications. First, low energy transmission efficiency is a major bottleneck. Although modern technology can achieve wireless energy transmission over a certain distance, energy loss remains significant, especially at longer distances and in harsh channel environments, where factors such as obstacle impedance and multipath loss exacerbate the energy loss. Second, energy multiplexing transmission systems also generate additional energy consumption during data transmission. To ensure the stability and reliability of data transmission, nodes in the energy multiplexing transmission system need to continuously perform data encoding, modulation, and demodulation operations to complete data exchange with the core base station; these operations consume energy. This energy consumption is particularly pronounced under high-speed data transmission and long-term operation. To address these issues, backscattering technology can provide a low-power, stable, and reliable solution for passive IoT.

[0004] Backscatter communication is a low-power wireless communication technology that transmits data by reflecting and modulating existing radio signals in the environment. This technology requires no separate transmitter or power supply; instead, it utilizes ambient wireless signals, such as television, Wi-Fi, or cell phone signals, reflecting them back to the receiver to transmit information. Backscatter devices typically consist of an antenna and simple modulation circuitry, encoding data by altering 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, contributing to long-term operation and battery-free operation.

[0005] Meanwhile, facing harsh and complex working environments, if the tag antenna is an omnidirectional antenna, it can receive radio frequency signals from all directions and efficiently harvest energy. However, due to the reciprocity of antennas, the signal is uniformly reflected to the surroundings, which may cause read failures or excessively long read times. Although the adaptive adjustment at the excitation source end can still work normally, it has a significant impact on the reader's operation. If the tag antenna is a directional antenna, it is difficult to receive enough signal from the environment for relaying and self-powering. Therefore, traditional tag antennas cannot be directly applied to environmental backscattering. A dual-antenna structure method is adopted to enable the tag to simultaneously possess energy storage and relay functions, achieving full signal coverage in complex areas. Summary of the Invention

[0006] To overcome the defects and shortcomings of existing technologies, this invention provides a backscatter-assisted signal-energy multiplexing transmission system. This system enables low-power, low-cost communication for passive IoT nodes and ensures that nodes can stably and efficiently acquire radio frequency signal energy in harsh and complex environments.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[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 an energy-carrying, unmodulated carrier signal and to 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 transmission switch, a rectifier and 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 acquire carrier signals, and the micro control unit is used to control the signal feedback switch to close and open, thereby changing the absorption or reflection state of the omnidirectional antenna on the incident signal.

[0012] The micro control unit is used to control the opening and closing of the data transmission switch and change the absorption or reflection state of the signal at the output of the directional coupler by the rectifier filter circuit.

[0013] When the signal feedback switch is closed, the input end of the directional coupler receives the signal acquired by the omnidirectional antenna and transmits the signal directionally to the output end of the directional coupler. 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 DC voltage to the power manager, and transmit part of the DC signal to the signal demodulation module.

[0015] The energy manager is used to boost DC voltage and transmit the energy storage status to the micro control unit;

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

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

[0018] The reader acquires the transmitted signal from the directional antenna and the collected information from 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, wherein the base station is connected to the transmitting antenna and the receiving antenna respectively;

[0020] The base station is used to generate an energy-carrying, unmodulated carrier signal, the transmitting antenna is used to transmit the carrier signal into free space, and the receiving antenna is used to receive the signal backscattered by the omnidirectional antenna.

[0021] As a preferred technical solution, both the transmitting antenna and the receiving antenna are circularly polarized, and their polarizations 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 from 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: 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, an RF signal input interface, and an RF signal output interface;

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

[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 has two field-effect transistors, one of which has its drain connected to the power supply VDD interface.

[0027] When the control signal input interface is high, FET2 is turned on and 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 low, FET2 is cut off, FET1 is turned on, and the signal feedback switch is closed.

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

[0030] As a preferred technical solution, the rectifier and filter circuit includes a bandpass filter, a harmonic suppressor, an RF rectifier, and a low-pass filter. The bandpass filter is used to filter out frequency band signals, the RF rectifier rectifies the output signal of the bandpass filter 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 information and energy multiplexing transmission subsystem adopts one or more of the following: temperature sensor, humidity sensor, and 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 acquire the transmitted signal of the directional antenna of the signal-energy multiplexing transmission subsystem, and the central processing unit is used to demodulate the signal acquired by the reader antenna to obtain the data collected by 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 an energy-carrying, unmodulated carrier signal and adjusts the radiation angle of the transmitted signal;

[0035] The signal multiplexing transmission subsystem acquires the carrier signal, and when the signal demodulation module demodulates the set prefix, it transmits the demodulation result to the micro control unit.

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

[0037] When the micro control unit detects through the energy manager that the current stored power has reached a set threshold, it disconnects the control data transmission switch 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 long distances without the need to install or replace batteries, and has low power consumption during operation. It 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 uses backscattering auxiliary nodes to complete communication with the excitation source and the reader. When the signal-energy multiplexing transmission subsystem is communicating, it only needs to control the closing and opening of the corresponding switches, without having to complete modulation and other operations, 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, making the overall system deployment flexible and adaptable to various working scenarios.

[0042] (4) In addition to collecting the signal energy emitted by the excitation source, the signal energy collected in free space can be collected and used to maintain normal operation. This 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. Attached Figure Description

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

[0044] Figure 2 This is a schematic diagram of a large-scale multi-node cluster operation scenario for the backscatter-assisted signal-energy multiplexing transmission system of the present invention.

[0045] Figure 3 This is a schematic diagram of the excitation source operation of the backscatter-assisted signal-energy multiplexing transmission system of the present invention.

[0046] Figure 4 This is a schematic diagram of the radio frequency switching circuit of the backscatter-assisted signal-energy multiplexing transmission system of the present invention.

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

[0048] Figure 6 This is a schematic diagram of the backscattering process of the backscattering subsystem of the backscattering-assisted signal-energy multiplexing transmission system of the present invention. Detailed Implementation

[0049] 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.

[0050] Example

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

[0052] In this embodiment, the excitation source includes a base station, a transmitting antenna, and a receiving antenna. The base station generates a simple carrier signal that carries energy and is not modulated, which is transmitted into free space by the transmitting antenna and captured by the omnidirectional antenna of the signal-energy multiplexing transmission subsystem. The polarization of the transmitting antenna and the receiving antenna of the excitation source is circular, but the polarization of the transmitting antenna and the receiving antenna are orthogonal to each other, which avoids crosstalk caused by sharing the channel in space. The circularly polarized backscattered signal can reduce the impact of multipath fading and improve 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. Any signal-energy multiplexing transmission subsystem can capture these signals, and each excitation source can simultaneously provide energy to multiple signal-energy multiplexing transmission subsystems.

[0054] like Figure 3As shown, the excitation source continuously transmits simple carrier signals carrying energy into free space to provide energy to the signal-energy multiplexing transmission subsystems within its range. After transmitting for a period of time g1, the excitation source modulates an interrogation message into the carrier to query the energy status and signal strength of each signal-energy multiplexing transmission subsystem within its range. During the waiting period g2, the source collects and demodulates the backscattered responses from the signal-energy multiplexing transmission subsystems. Subsequently, it comprehensively evaluates the energy status and received energy signal strength of each signal-energy multiplexing transmission subsystem. If a node is found to be in a state of insufficient energy supply, the source will adjust the radiation angle of the transmitted signal or adjust the transmission power if necessary, so that the signal can better cover the node. During this period, the excitation source will continue to transmit 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 transmission 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 through free space to the energy-induction multiplexing transmission subsystem. The signal is captured by the omnidirectional antenna of the energy-induction multiplexing transmission subsystem and enters the rectifier and filter circuit through the directional coupler, realizing the RF-DC conversion and demodulation of the input signal. The energy-induction multiplexing transmission subsystem controls the backscattering of the omnidirectional antenna by controlling the signal feedback switch, thereby feeding back its relevant operating status to the excitation source. After receiving the feedback information from the energy-induction multiplexing transmission subsystem, the excitation source can adjust the transmission angle of the excitation signal according to actual needs, thereby changing the energy density within the radiation range and realizing backscattering-assisted adaptive energy input. At the same time, the sensors of the energy-induction multiplexing transmission subsystem can collect the required parameters and control the data transmission switch through the energy-induction multiplexing transmission subsystem, so that the signal flows to the directional antenna through the directional coupler. The directional antenna transmits data to the reader, and finally the reader obtains the sensor data, thereby reducing the power consumption of the energy-induction multiplexing transmission system and improving the degree of freedom of deployment of the energy-induction multiplexing transmission system in complex environments.

[0057] In this embodiment, the omnidirectional antenna is circularly polarized and is the same as the transmitting antenna of the excitation source. Therefore, it can capture the signal transmitted by the transmitting antenna in free space. At the same time, the circularly polarized signal reduces the energy loss caused by multipath interference and polarization angle mismatch, and maximizes the received energy.

[0058] The polarizations 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 of the reflected signal matches that of the receiving antenna, so the backscattered signal from the omnidirectional antenna can be received.

[0059] Omnidirectional antennas have a wide radiation angle, thus they can receive signals from a wide range of incident angles. This ensures that the omnidirectional antenna can still receive signals from the transmitting antenna even when the transmitting antenna of the excitation source is not precisely aligned, thereby improving the fault tolerance and stability of the system.

[0060] Meanwhile, the omnidirectional antenna can also receive other radio frequency signals over a wide angle range, which are then rectified and filtered to provide additional energy.

[0061] A signal feedback switch is an RF switch composed of lumped components such as transistors, resistors, and capacitors, containing power supply VDD, ground GND, and control signal input VDD. CTRL Radio frequency signal input RF IN and radio frequency 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 FETs; when V CTRL When V is high, FET2 is turned on, while FET1 is turned off by the inverter NG, presenting a high impedance state. At this time, the RF switch is in an open circuit state, that is, the switch is open; when V CTRL When the signal is low, FET2 is off, while FET1 is turned on by the inverter NG, thus RF... IN The signal can be successfully 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 or low level of the control signal determines whether the two interfaces of the RF signal input and RF signal output are connected. When the control signal is high, the switch is open, and when the control signal is low, the switch is closed. The control signal is issued 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. The omnidirectional antenna absorbs the incident signal. When the signal feedback switch is open, the signal cannot enter the signal-energy multiplexing transmission subsystem from the omnidirectional antenna. As a result, the omnidirectional antenna reflects the incident signal.

[0065] By controlling the opening and closing of the signal feedback switch, the absorption or reflection state of the omnidirectional antenna to the incident signal can be changed, so that backscattering and excitation source communication can be used, and the omnidirectional antenna can be controlled to feed information back to the receiving antenna using a specific coding method.

[0066] The signal feedback switch closes when the control signal is low, allowing the signal to flow from the omnidirectional antenna to the directional coupler. This enables the RF-DC conversion of signal energy, providing power to the signal-energy multiplexing transmission subsystem. It also reduces unnecessary power consumption of the signal feedback switch during charging, thus improving 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 the input terminal, the output terminal, and the coupling terminal according to their functions. The omnidirectional antenna and the signal feedback switch are connected in sequence to the input terminal. The output terminal is connected to the rectifier and filter circuit through the data transmission switch. The coupling terminal is connected to the directional antenna.

[0069] like Figure 5 As shown, the core of the directional coupler circuit is a square structure composed of four arms. Three ports and one ground port are led out from the vertices of the square structure, similar to a branch-line coupler with a grounded isolation terminal. The three ports are denoted as ①, ②, and ③, where port ① is the input, port ② is the output, and port ③ is the coupling terminal. All four arms of the directional coupler circuit are quarter-wavelength (90°) lines of the operating frequency, with characteristic impedances of 50Ω, 25Ω, 50Ω, and 25Ω, respectively, where n is an integer. Ideally, the incident wave a1 enters the directional coupler from the input terminal. During charging, signal b2 flows from the input terminal to the output terminal, and signal b3 flows to the isolation terminal. Due to the output terminal matching and the isolation terminal being short-circuited to ground, only the isolation terminal generates reflected signal a3, and part of the signal b4 is reflected to the coupling terminal. Therefore:

[0070]

[0071] It can be seen that at this time, the output of the coupling terminal is only the output of the output terminal. When the output terminal is open-circuited, both the output terminal and the isolation terminal t undergo total internal reflection simultaneously, then:

[0072]

[0073] At this point, the input end is perfectly matched, no reflected signal passes through, and all incident signals flow to the coupling end.

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

[0075] When the output is open-circuited with a load, the input and output impedances at the output are mismatched. The input signal will be reflected at the output and directionally transmitted to the coupling end in the directional coupler, and finally the signal flows to the directional antenna.

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

[0077] When the data transmission switch is working normally, its opening or closing is determined by the level of the control signal, which is issued by the micro control unit.

[0078] When the control signal is low, the switch is closed, the input and output impedances of the directional coupler are well matched, the rectifier and filter circuit absorbs the signal at the output, and the signal flows through the directional coupler to the rectifier and filter circuit to complete the signal reception and RF-DC conversion.

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

[0080] When the data transmission switch is closed, the signal flows to the rectifier and filter circuit, ensuring low power consumption during normal operation and improving the system's battery life.

[0081] The data transmission switch changes the state of signal absorption or reflection by altering its closed or open state. This enables the modulation of the incident signal received by the omnidirectional antenna using a specific coding method, and then transmits it through a directional antenna, reducing the power consumption of the signal-energy multiplexing transmission subsystem when sending messages to the reader.

[0082] The rectifier and filter circuit includes a bandpass filter, a harmonic suppressor, an RF rectifier, and a low-pass filter. When both the signal feedback switch and the data transmission switch are closed, the signal received by the omnidirectional antenna flows sequentially through the signal feedback switch and the directional coupler. When the signal enters the rectifier and filter circuit, the input signal is filtered out by the bandpass filter to remove signals from other frequency bands. Subsequently, the signal is rectified into a DC signal in the RF rectifier circuit. In the rectifier circuit, the high-order harmonics generated by the diodes are repeatedly reflected between the harmonic suppressor and the low-pass filter and are gradually rectified into a DC signal by the RF rectifier, thereby maximizing the rectified signal energy. Finally, the AC signal is transformed into a smooth DC voltage to supply the subsequent power manager or information demodulation circuit.

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

[0084] The signal demodulation module can use part of the output of the rectifier 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 scenario, including but not limited to temperature, humidity, light and other sensors. The sensor module uses the energy collected in free space by the signal-energy multiplexing transmission subsystem to maintain normal operation and transmits the obtained data to the micro control unit for storage.

[0086] The micro control unit periodically checks the current power level. If the power level reaches a set threshold Q, it controls the data transmission switch. During control, the data is modulated onto a signal according to the encoding method used, enabling the transmission of data acquired by the sensor to the reader.

[0087] Directional antennas have narrow beam angles and concentrated radiated energy, enabling them to provide directional radiation over long communication distances.

[0088] The signal-energy multiplexing transmission subsystem consisting of a directional antenna and an omnidirectional antenna is a dual-antenna system. The system is relatively flexible in its location deployment and will not affect the alignment between the directional antenna and the reader.

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

[0090] After the reader antenna captures the signal transmitted into free space by the directional antenna of the signal-energy multiplexing transmission subsystem, it transmits the signal to the central processing unit for demodulation, thereby obtaining relevant information acquired by the sensor module in the signal-energy multiplexing transmission subsystem.

[0091] like Figure 6 As shown, when the signal-energy multiplexing transmission subsystem captures a radio frequency signal in free space, since all switches are in the closed state by default, the signal passes through a rectification and filtering circuit to become a relatively smooth DC signal. Part of the output DC signal is sent to the signal demodulation module for demodulation by a power divider circuit. When the demodulation detects a specific prefix in the received signal, it informs the microcontroller of the demodulation result. The microcontroller then makes a judgment. If the determination finds that the demodulation result is a query signal, it controls the signal feedback switch to perform backscattering; otherwise, it executes the corresponding instruction. If the demodulation result does not contain a specific prefix, it means that the signal does not contain information from the excitation source. The subsystem node continues to perform rectification, filtering, and charging operations, and stores the obtained DC signal in a capacitor after being boosted by the energy manager. When the microcontroller queries the energy manager and finds that the current stored power has reached the set threshold Q, it will pause the charging operation and instead transmit data to the reader.

[0092] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A backscatter-assisted signal-energy multiplexing transmission system, characterized in that, include: Excitation source, signal-energy multiplexing transmission subsystem, and reader; The excitation source is used to transmit an energy-carrying, unmodulated carrier signal and to 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 transmission switch, a rectifier and 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 acquire carrier signals, and the micro control unit is used to control the signal feedback switch to close and open, thereby changing the absorption or reflection state of the omnidirectional antenna on the incident signal. The micro control unit is used to control the opening and closing of the data transmission switch and change the absorption or reflection state of the signal at the output of the directional coupler by the rectifier filter circuit. When the signal feedback switch is closed, the input end of the directional coupler receives the signal acquired by the omnidirectional antenna and transmits the signal directionally to the output end of the directional coupler. 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 DC voltage to the power manager, and transmit part of the DC signal to the signal demodulation module; The energy manager is used to boost DC voltage and transmit the energy storage status to the micro control unit; The signal demodulation module is used to demodulate the signal and output the demodulation result to the micro control unit. The micro control unit is used to acquire the information collected by the sensor module and control the closing and opening of the signal feedback switch and the data transmission switch according to the demodulation results; The reader acquires the transmitted signal from the directional antenna and the collected information from 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, wherein the base station is connected to the transmitting antenna and the receiving antenna, respectively. The base station is used to generate an energy-carrying, unmodulated carrier signal, the transmitting antenna is used to transmit the carrier signal into free space, and the receiving antenna is used to receive the signal backscattered by the omnidirectional antenna.

3. The backscatter-assisted signal-energy multiplexing transmission system according to claim 2, characterized in that, Both the transmitting and receiving antennas are circularly polarized, and their polarizations are orthogonal to each other.

4. The backscatter-assisted signal-energy multiplexing transmission system according to claim 2, characterized in that, The omnidirectional antenna is circularly polarized, and the polarizations of the omnidirectional antenna and the receiving antenna are orthogonal to each other. When the omnidirectional antenna reflects the signal from the transmitting antenna through backscattering, the polarization of the reflected signal matches that 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: field-effect transistor FET1, field-effect transistor FET2 and inverter, as well as power supply VDD interface, ground GND interface, control signal input interface, radio frequency signal input interface and radio frequency signal output interface; The micro control unit is connected to the control signal input interface, which is connected to the gate of the field-effect transistor FET1 via an inverter. The source and drain of the field-effect transistor FET1 are connected to the radio frequency signal input interface and the radio frequency signal output interface, respectively. 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 has two field-effect transistors, one of which has its drain connected to the power supply VDD interface. When the control signal input interface is high, FET2 is turned on and 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 low, FET2 is cut off, FET1 is turned on, and the signal feedback switch is closed.

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

7. The backscatter-assisted signal-energy multiplexing transmission system according to claim 1, characterized in that, The rectifier and filter circuit includes a bandpass filter, a harmonic suppressor, an RF rectifier, and a low-pass filter. The bandpass filter is used to filter out frequency band signals, the RF rectifier rectifies the output signal of the bandpass filter 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.

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 uses one or more of the following: temperature sensor, humidity sensor, and 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 acquire the transmitted signal from the directional antenna of the signal-energy multiplexing transmission subsystem. The central processing unit is used to demodulate the signal acquired by the reader antenna to obtain the data collected by the sensor module of the signal-energy multiplexing transmission subsystem.

10. The control method for the backscatter-assisted signal-energy multiplexing transmission system according to any one of claims 1-9, characterized in that, Includes the following steps: The excitation source transmits an energy-carrying, unmodulated carrier signal and adjusts the radiation angle of the transmitted signal; The signal multiplexing transmission subsystem acquires the carrier signal, and when the signal demodulation module demodulates the set prefix, it transmits the demodulation result to the micro control unit. When the micro control unit determines that the demodulation result is a query signal, it controls the signal feedback switch to perform backscattering; when the demodulation result does not contain a set prefix, it controls the data transmission switch to close. When the micro control unit detects through the energy manager that the current stored power has reached a set threshold, it disconnects the control data transmission switch and transmits data to the reader.

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