An environment backscatter communication system based on phase deviation reconstruction

Abstract

The application provides an environment backscattering communication system based on phase deviation reconstruction, which comprises a radio frequency signal source, a terminal device and a receiving device; the radio frequency signal source transmits radio frequency signals to the terminal device through a first path hst and transmits radio frequency signals to the receiving device through a second path hsr; the terminal device selects whether to reflect the radio frequency signals transmitted through the first path hst to the receiving device through a third path htr or not according to the binary data to be transmitted; the receiving device recovers the binary signal waveform by superimposing the radio frequency signals transmitted through the second path hsr and the radio frequency signals reflected by the terminal device through the third path htr and detecting through an envelope detector. The application solves the problem that the phase inconsistency between the radio frequency signals reflected by the terminal device and the radio frequency signals transmitted by the radio frequency signal source in the environment backscattering communication system leads to communication failure.

Description

Technical Field

[0001] This invention relates to an environmental backscatter communication system based on phase deviation reconstruction, belonging to the fields of wireless communication and the Internet of Things. Background Technology

[0002] With the rapid development of the global information industry, 6G technology has become a key research focus for countries worldwide. 6G's design concept of "Internet of Everything, Intelligent Internet of Everything" has greatly promoted the rapid development of the Internet of Things (IoT). Environmental backscattering technology, with its low power consumption, self-powered operation, wide spectrum coverage, and low cost, has secured a place in the development of 6G technology and the IoT. Environmental backscattering communication systems transmit information by carrying radio frequency signals in the environment, reducing the cost of deploying dedicated radio frequency signal sources and improving the utilization rate of spectrum resources. By adjusting the matching performance between the antenna and the radio frequency circuit, the communication system achieves self-powered operation and communication functions. When the antenna and radio frequency circuit are matched, it can absorb wireless signals in the environment and convert them into electrical energy. When the antenna and radio frequency circuit are mismatched, it enables the terminal device to transmit information to the receiving device, completing the communication process.

[0003] In environmental backscatter communication systems, the key focus is on data communication quality. Therefore, ensuring data communication at any location is fundamental to the widespread application of such systems. Currently, environmental backscatter communication widely uses OOK (On-Off Keying) modulation, which effectively reduces the power consumption of terminal devices. Terminal devices control the matching circuit to reflect or not reflect radio frequency (RF) signals from the environment. The receiving device receives both the RF signals from the environment and the RF signals reflected by the terminal device, and determines whether the terminal device is reflecting a signal by judging the power of the RF signals. Because the RF signals reflected by the terminal device received at the antenna of the receiving device cannot always maintain the same phase as the RF signals transmitted by the signal source, there may be situations where the voltage values ​​of the RF signals reflected by the terminal device and those without are the same after detection, resulting in zero transmitted data, or the voltage values ​​of the RF signals reflected by the terminal device are smaller after detection than those without, resulting in reversed data transmission and communication failure.

[0004] Therefore, it is very important to solve the problem of communication failure caused by the phase mismatch between the radio frequency signal reflected by the terminal device and the radio frequency signal emitted from the radio frequency signal source in the environmental backscatter communication system. Summary of the Invention

[0005] This invention proposes an environmental backscatter communication system based on phase deviation reconstruction, which aims to solve the problem of communication failure caused by the inconsistency between the phase of the radio frequency signal reflected by the terminal device and the radio frequency signal emitted by the radio frequency signal source in the environment.

[0006] The technical solution of this invention is an environmental backscatter communication system based on phase deviation reconstruction. Its structure includes a radio frequency (RF) signal source, a terminal device, and a receiving device. The RF signal source transmits RF signals to the terminal device via a first path (HST) and a second path (HSR) to the receiving device. The terminal device selects whether to reflect the RF signal transmitted via the first path (HST) to the receiving device via a third path (HTR) or not, depending on the binary data to be transmitted. The receiving device superimposes the RF signal transmitted via the second path (HSR) and the RF signal reflected by the terminal device via the third path (HTR) and performs detection using an envelope detector to recover the binary signal waveform.

[0007] Furthermore, the radio frequency signal generated by the radio frequency signal source is as shown in formula (1):

[0008] x(t) = Acos(ωt) (1);

[0009] Where: x(t) represents the radio frequency signal generated by the radio frequency signal source, A represents the amplitude of the radio frequency signal, ω=2π / T=2πf, ω represents the angular velocity, and T and f represent the period and frequency of the radio frequency signal, respectively.

[0010] Further, the terminal device includes a first microcontroller, a phase control unit, a first matching circuit, a 0-phase offset path, a π / 2-phase offset path, and a first antenna; the signal output terminal of the first microcontroller is connected to the signal input terminal of the phase control unit, the output terminal of the phase control unit is connected to the input terminal of the first matching circuit, the first signal output terminal of the first matching circuit is connected to the signal input terminal of the 0-phase offset path, the second signal output terminal of the first matching circuit is connected to the signal input terminal of the π / 2-phase offset path, the signal output terminal of the 0-phase offset path is connected to the first signal input terminal of the first antenna, and the signal output terminal of the π / 2-phase offset path is connected to the second signal input terminal of the first antenna; during operation, the first microcontroller generates binary data and transmits the binary data to the phase control unit; the phase control unit first selects the 0-phase offset path... The first matching circuit is connected to the first antenna via a 0-phase offset path. By controlling the matching characteristics of the first matching circuit with the 0-phase offset path and the first antenna using binary data, OOK modulation is performed to reflect or not reflect the radio frequency signal passing through the first path hst. When reflected, a first set of reflected radio frequency signals is formed, enabling the transmission of binary data. After the binary data transmission is completed, the phase control unit selects a π / 2 phase offset path. The first matching circuit is connected to the first antenna via the π / 2 phase offset path. By controlling the matching characteristics of the first matching circuit with the π / 2 phase offset path and the first antenna using binary data, OOK modulation is performed to reflect or not reflect the radio frequency signal passing through the first path hst. When reflected, a second set of reflected radio frequency signals is formed, enabling the retransmission of binary data.

[0011] Furthermore, the binary data controls the first matching circuit to perform OOK modulation with the 0-phase offset path and the first antenna, realizing the reflection or non-reflection of the radio frequency signal passing through the first path hst. Specifically, this includes: the radio frequency signal passing through the first path hst enters the terminal device through the first antenna and the 0-phase offset path; when the first matching circuit is impedance matched with the 0-phase offset path and the first antenna, the radio frequency signal passing through the first path hst entering the terminal device is not reflected; when the first matching circuit is impedance mismatched with the 0-phase offset path and the first antenna, the radio frequency signal passing through the first path hst entering the terminal device is reflected into the environment along the 0-phase offset path and the first antenna, forming a first set of reflected radio frequency signals; the binary data controls the first matching circuit to perform OOK modulation with the first antenna. The matching characteristics of the π / 2 phase offset path and the first antenna are used for OOK modulation to achieve the reflection or non-reflection of the radio frequency signal passing through the first path hst. Specifically, the radio frequency signal passing through the first path hst enters the terminal device through the first antenna and the π / 2 phase offset path. When the first matching circuit matches the impedance of the π / 2 phase offset path and the first antenna, the radio frequency signal passing through the first path hst entering the terminal device is not reflected. When the first matching circuit does not match the impedance of the π / 2 phase offset path and the first antenna, the radio frequency signal passing through the first path hst entering the terminal device is reflected into the environment along the π / 2 phase offset path and the first antenna, forming a second set of reflected radio frequency signals. The phase difference between the first set of reflected radio frequency signals and the second set of reflected radio frequency signals is π / 2.

[0012] Further, the receiving device includes a second antenna, a second matching circuit, an envelope detector, a reverse detection unit, and a second microcontroller; wherein, the signal output terminal of the second antenna is connected to the signal input terminal of the second matching circuit, the signal output terminal of the second matching circuit is connected to the signal input terminal of the envelope detector, the signal output terminal of the envelope detector is connected to the signal input terminal of the reverse detection unit, and the signal output terminal of the reverse detection unit is connected to the signal input terminal of the second microcontroller; during operation, the second antenna is connected to the second matching circuit, and the second antenna receives radio frequency signals from the environment and transmits them to the second matching circuit. The radio frequency signals in the environment include radio frequency signals transmitted through the second path HSR and radio frequency signals reflected by the terminal device through the third path HTR. The second matching circuit transmits the radio frequency signals from the environment... The radio frequency (RF) signal is transmitted to the envelope detector. The envelope detector performs peak envelope detection on the RF signal transmitted by the second matching circuit, recovers the smooth binary signal waveform, and transmits the binary signal waveform to the inverse detection unit. The inverse detection unit acquires the received data from the binary signal waveform and determines whether the start bit of the received data is a rising edge or a falling edge. If it is a rising edge, the received data is in the same direction as the binary data sent by the terminal device and is transmitted to the second microcontroller. If it is a falling edge, the received data is in the opposite direction to the binary data sent by the terminal device and is inverted and transmitted to the second microcontroller. The second microcontroller is connected to the inverse detection unit and receives the received data from the inverse detection unit, completing the communication process between the terminal device and the receiving device.

[0013] Furthermore, the phase control unit first selects a 0-phase offset path, the first matching circuit is connected to the first antenna through the 0-phase offset path, and performs OOK modulation by controlling the matching characteristics of the first matching circuit with the 0-phase offset path and the first antenna using binary data, thereby realizing the reflection or non-reflection of the radio frequency signal passing through the first path hst, specifically including:

[0014] 1) When the binary data that the terminal device needs to send is 1, the terminal device is controlled to reflect the radio frequency signal. At this time, the radio frequency signal generated by the radio frequency signal source is reflected through the first path hst and the first antenna and 0 phase offset path in the terminal device to form the first set of reflected radio frequency signals. The first set of reflected radio frequency signals is as shown in formula (2):

[0015]

[0016] Where: x1(t) is the first group of reflected radio frequency signals; The phase value of the first group of reflected radio frequency signals at the first antenna position of the terminal device. It exhibits periodicity with a period of 2π; ηα hstA represents the amplitude of the radio frequency signal received by the receiving device from the terminal device; η is the reflection coefficient of the terminal device, which represents the signal attenuation intensity after the radio frequency signal is reflected by the terminal device; α hst α is the attenuation coefficient of the radio frequency signal on the first path hst. hst B(n) represents the signal attenuation strength of the radio frequency signal after passing through the first path hst, and B(n) represents the binary data sent by the terminal device.

[0017] 2) When the binary data that the terminal device needs to send is 0, the terminal device does not reflect radio frequency signals;

[0018] The phase control unit then selects a π / 2 phase offset path. The first matching circuit is connected to the first antenna via the π / 2 phase offset path. By controlling the matching characteristics of the first matching circuit with the π / 2 phase offset path and the first antenna using binary data, an OOK modulation function is performed to achieve the reflection or non-reflection of the RF signal passing through the first path hst. Specifically, this includes:

[0019] 1) When the binary data to be sent by the terminal device is 1, the radio frequency signal generated by the radio frequency signal source is reflected by the first path hst and the first antenna and π / 2 phase offset path in the terminal device to form a second set of reflected radio frequency signals. The second set of reflected radio frequency signals is shown in formula (3):

[0020]

[0021] Where: x2(t) is the second set of reflected radio frequency signals; The phase value of the second set of reflected radio frequency signals at the first antenna position of the terminal device. It exhibits periodicity with a period of 2π; ηα hst A represents the amplitude of the radio frequency signal received by the receiving device from the terminal device; η is the reflection coefficient of the terminal device, which represents the signal attenuation intensity after the radio frequency signal is reflected by the terminal device; α hst Let α be the attenuation coefficient of the source signal on the first path hst. hst B(n) represents the signal attenuation strength of the radio frequency signal after passing through the first path hst, and B(n) represents the binary data sent by the terminal device.

[0022] 2) When the binary data that the terminal device needs to send is 0, the terminal device does not reflect the radio frequency signal; after the π / 2 phase offset path has finished sending the binary data, the terminal device completes the data transmission.

[0023] Furthermore, when the terminal device reflects a radio frequency (RF) signal, the receiving device receives the superposition of the RF signal generated by the RF signal source in the environment and the reflected RF signal from the terminal device; when the terminal device does not reflect a RF signal, the receiving device receives the RF signal generated by the RF signal source in the environment; the reflected RF signal is either a first set of reflected RF signals or a second set of reflected RF signals; when the receiving device receives the superposition of the RF signal generated by the RF signal source in the environment and the first set of reflected RF signals from the terminal device, the RF signal generated by the RF signal source and the first set of reflected RF signals from the terminal device are superimposed to form a first set of RF signals; when the receiving device receives the superposition of the RF signal generated by the RF signal source in the environment and the second set of reflected RF signals from the terminal device, the RF signal generated by the RF signal source and the second set of reflected RF signals from the terminal device are superimposed to form a second set of RF signals.

[0024] Furthermore, the waveform function of the first group of radio frequency signals includes the radio frequency signal generated by the radio frequency signal source and the first group of reflected radio frequency signals reflected by the terminal device through the 0-phase offset path; the waveform function of the first group of radio frequency signals is shown in formula (4):

[0025]

[0026] Where: y1(t) is the first group of radio frequency signals; α hsr A represents the amplitude of the radio frequency signal received by the receiving device from the radio frequency signal source; α hsr α is the source signal attenuation coefficient on the second path hsr. hsr ηα represents the signal attenuation intensity of the radio frequency signal after passing through the second path HSR. hst α htr A represents the amplitude of the reflected radio frequency signal received by the receiving device from the terminal device; α htr α is the source signal attenuation coefficient on the third path htr. htr η represents the signal attenuation intensity of the radio frequency signal after passing through the third path htr; η is the reflection coefficient of the terminal device; θ is the phase value of the radio frequency signal received by the receiving device from the radio frequency signal source. The phase value of the first set of reflected radio frequency signals received by the receiving device from the terminal device; The phase deviation is the difference between the first set of reflected radio frequency signals received by the receiving device from the terminal device and the radio frequency signals generated by the radio frequency signal source; phase deviation It is periodic with a period of 2π; B(n) is the binary data sent by the terminal device.

[0027] Furthermore, the waveform function of the second set of radio frequency signals includes the radio frequency signal generated by the radio frequency signal source and the second set of reflected radio frequency signals reflected by the terminal device through the π / 2 phase offset path; the waveform function of the second set of radio frequency signals is shown in formula (5):

[0028]

[0029] Where: y2(t) is the second group of radio frequency signals; α hsr A represents the amplitude of the radio frequency signal received by the receiving device from the radio frequency signal source; α hsr α is the attenuation coefficient of the source signal on the second path HSR. hsr ηα represents the signal attenuation intensity of the radio frequency signal after passing through the second path, hsr; hst α htr A represents the amplitude of the radio frequency signal reflected from the terminal device received by the receiving device; α htr α is the attenuation coefficient of the source signal on the third path htr. htr θ represents the signal attenuation intensity of the radio frequency signal after passing through the third path htr; θ is the phase value of the radio frequency signal received by the receiving device from the signal source. The phase value of the second set of reflected radio frequency signals received by the receiving device from the terminal device; The phase deviation between the second set of reflected radio frequency signals received by the receiving device from the terminal device and the radio frequency signals received from the radio frequency signal source; phase deviation It exhibits periodicity with a period of 2π; B(n) represents the valid binary data of the terminal device; This indicates that the phase difference between the first group of radio frequency signals and the second group of radio frequency signals is...

[0030] Furthermore, the workflow of the receiving device includes:

[0031] 1) In the environmental backscatter communication system, the receiving equipment first receives the first set of radio frequency signals.

[0032] If the transmitted data in the binary data sent by the terminal device is 0, and B(n) = 0, then the terminal device does not reflect the radio frequency signal. At this time, the first set of radio frequency signals received by the receiving device is as shown in formula (6):

[0033] y1(t)=α hsr Acos(ωt+θ) (6);

[0034] If the binary data sent by the terminal device contains 1 and B(n) = 1, then the radio frequency signal is reflected. At this time, the first set of radio frequency signals received by the receiving device is as shown in formula (7):

[0035]

[0036] Perform the transformation operation on formula (7) as shown in formula (8) - formula (10):

[0037]

[0038]

[0039] y1(t)=K1(cos(ωt+θ)cθsγ1-sin(ωt+θ)sinγ1)=K1cos(ωt+θ+γ1) (10);

[0040] in:

[0041]

[0042]

[0043]

[0044] K1 represents the superimposed amplitude of the radio frequency signal received by the receiving device from the radio frequency signal source and the first set of reflected radio frequency signals reflected by the terminal device through the 0 phase offset path, i.e., the amplitude of the first set of radio frequency signals.

[0045] Let the amplitudes of the radio frequency signals in formulas (6) and (10) be equal, and find the phase position where the amplitude of the first set of radio frequency signals is equal to the amplitude of the radio frequency signal from the radio frequency signal source, as shown in formula (11):

[0046] α hsr A = K1 (11);

[0047] Perform the transformation operation on formula (11) as shown in formula (12) - formula (16):

[0048]

[0049]

[0050]

[0051]

[0052] or

[0053] At this time, if or Then K1>α hsr A, The amplitude K1 of the first group of radio frequency signals is greater than the amplitude α of the radio frequency signal generated only from the radio frequency signal source.hsr A. The envelope detector detects the first group of radio frequency signals and recovers the waveform of the first group of binary signals. The reverse detection unit samples the waveform of the first group of binary signals and recovers the first group of binary 01 data. The first data waveform is detected as a rising edge. At this time, the binary data sent by the terminal device is in the same direction as the first group of binary 01 data recovered by the reverse detection unit, and the binary data sent by the terminal device can be obtained directly.

[0054] like Then K1α hsr A, the amplitude K1 of the first group of radio frequency signals is less than the amplitude α of the radio frequency signal generated only from the radio frequency signal source. hsr A. The envelope detector detects the first group of radio frequency signals and recovers the waveform of the first group of binary signals. The reverse detection unit samples the waveform of the first group of binary signals and recovers the first group of binary 01 data. The first data waveform is detected as a falling edge. At this time, the binary data sent by the terminal device is the reverse of the first group of binary 01 data recovered by the reverse detection unit. The binary data transmitted by the terminal device is obtained by inverting the first group of binary 01 data recovered by the reverse detection unit. The data inversion means changing the 0 in the binary 01 data recovered by the reverse detection unit to 1 and the 1 to 0.

[0055] like or Then K1 = α hsr A, the amplitude K1 of the first group of radio frequency signals is equal to the amplitude α of the radio frequency signal generated only from the radio frequency signal source. hsr A. The envelope detector detects the first set of radio frequency signals and recovers the waveform of the first set of binary signals. The reverse detection unit samples the waveform of the binary signals and recovers the waveform of the first set of binary signals, which is all 0. It is impossible to distinguish whether it is a rising edge or a falling edge, and it is impossible to recover the binary data transmitted by the terminal device. At this time, it is necessary to receive the second set of radio frequency signals for judgment.

[0056] 2) In the environmental backscatter communication system, if the second set of radio frequency signals is received by the receiving device, and the transmitted data in the binary data sent by the terminal device is 0, B(n) = 0, then the terminal device does not reflect the radio frequency signal. At this time, the second set of radio frequency signals received by the receiving device is as shown in formula (17):

[0057] y2(t)=α hsr Acos(ωt+θ) (17);

[0058] If the binary data sent by the terminal device contains 1 and B(n) = 1, then the reflected radio frequency signal will be received by the receiving device as shown in formula (18):

[0059]

[0060] Perform the transformation operation on formula (18) as shown in formula (19) - formula (22):

[0061]

[0062]

[0063]

[0064] y2(t)=K2(cos(ωt+θ)cosγ2-sin(ωt+θ)sinγ2)=K2cos(ωt+θ+Y2) (22);

[0065] in:

[0066]

[0067]

[0068]

[0069] K2 represents the superposition amplitude of the radio frequency signal received by the receiving device and the second set of reflected radio frequency signals reflected by the terminal device through the π / 2 phase offset path, i.e., the amplitude of the second set of radio frequency signals;

[0070] The amplitude of the radio frequency signal received by the receiving device and generated by the radio frequency signal source is compared with that of the second group of radio frequency signals:

[0071] K2 represents the amplitude of the second group of radio frequency signals, α hsr A represents the amplitude of the radio frequency signal generated from the radio frequency signal source, therefore K2 and α hsr A is greater than 0;

[0072]

[0073]

[0074]

[0075]

[0076]

[0077] like

[0078]

[0079] Because the backscattering from the second path (hsr) is less than the sum of the first path (hst) and the third path (htr), and the reflection coefficient of the terminal device (η) is less than 1, the amplitude α of the radio frequency signal reaching the receiving device through the second path (hsr) is... hsr A is definitely greater than the amplitude ηα of the radio frequency signal that reaches the receiving device after passing through the first path hst, the third path htr, and the reflection from the terminal device. hst α htr A, therefore

[0080]

[0081] therefore K2 represents the amplitude of the second group of radio frequency signals, α hsr A represents the amplitude of the radio frequency signal generated from the radio frequency signal source, therefore K2 and α hsr If A is greater than 0, then K2 < α hsr A, the amplitude K2 of the second group of radio frequency signals is less than the amplitude α of the radio frequency signal generated only from the radio frequency signal source. hsr A. The envelope detector detects the second group of radio frequency signals and recovers the waveform of the second group of binary signals. The reverse detection unit samples the waveform of the second group of binary signals and recovers the second group of binary 01 data. The first data waveform is detected as a falling edge. At this time, the binary data sent by the terminal device is the inverse of the second group of binary 01 data recovered by the reverse detection unit. The binary data transmitted by the terminal device is obtained by inverting the second group of binary 01 data recovered by the reverse detection unit.

[0082] like

[0083]

[0084]

[0085] Because the backscattering from the second path (hsr) is less than the sum of the first path (hst) and the third path (htr), and the reflection coefficient of the terminal device (η) is less than 1, the amplitude α of the radio frequency signal reaching the receiving device through the second path (hsr) is... hsr A is definitely greater than the amplitude ηα of the radio frequency signal that reaches the receiving device after passing through the first path hst, the third path htr, and the reflection from the terminal device. hst α htr A, therefore

[0086]

[0087] therefore, K2 and α hsr If A is greater than 0, then K2 > α hsrA, The amplitude K2 of the second group of radio frequency signals is greater than the amplitude α of the radio frequency signal generated only from the radio frequency signal source. hsr A. The envelope detector detects the second group of radio frequency signals and recovers the waveform of the second group of binary signals. The reverse detection unit samples the waveform of the second group of binary signals and recovers the second group of binary 01 data. It detects that the first data waveform is a rising edge. At this time, the binary data sent by the terminal device is in the same direction as the second group of binary 01 data recovered by the reverse detection unit, and the binary data sent by the terminal device is directly obtained.

[0088] The beneficial effects of this invention are:

[0089] 1) This invention solves the problem of communication failure caused by the phase mismatch between the radio frequency signal reflected by the terminal device and the radio frequency signal emitted by the radio frequency signal source in the environment in an environmental backscatter communication system;

[0090] 2) Through further design, this invention, through reverse data detection, can invert the reverse data and recover the data sent by the terminal device when the receiving device collects reverse data;

[0091] 3) Through further design, this invention uses the reflection of two sets of phase-difference devices in the terminal equipment. The phase-based radio frequency signal solves the problem that the voltage value after detection is consistent whether the received radio frequency signal contains a terminal device reflection signal or not. Attached Figure Description

[0092] Appendix Figure 1 This is a schematic diagram of the structure of an environmental backscatter communication system.

[0093] Appendix Figure 2 This is a structural diagram of a terminal device for an environmental backscatter communication system based on phase deviation reconstruction.

[0094] Appendix Figure 3 This is a structural diagram of the receiving device in an environmental backscatter communication system based on phase deviation reconstruction. Detailed Implementation

[0095] An environmental backscatter communication system based on phase deviation reconstruction includes a radio frequency (RF) signal source, a terminal device, and a receiving device. The RF signal source transmits RF signals to the terminal device via a first path (hst) and a second path (hsr) to the receiving device. The terminal device selects whether to reflect the RF signal transmitted via the first path (hst) to the receiving device via a third path (htr) or not, depending on the binary data to be transmitted. The receiving device reconstructs the binary signal waveform by superimposing the RF signal transmitted via the second path (hsr) and the RF signal reflected by the terminal device via the third path (htr) and performing detection using an envelope detector.

[0096] The radio frequency signal generated by the radio frequency signal source is as shown in formula (1):

[0097] X(t) = Acos(ωt) (1);

[0098] Where: x(t) represents the radio frequency signal generated by the radio frequency signal source, A represents the amplitude of the radio frequency signal, ω=2π / T=2πf, ω represents the angular velocity, and T and f represent the period and frequency of the radio frequency signal, respectively.

[0099] The terminal device includes a first microcontroller, a phase control unit, a first matching circuit, a 0-phase offset path, a π / 2-phase offset path, and a first antenna. The signal output terminal of the first microcontroller is connected to the signal input terminal of the phase control unit, the output terminal of the phase control unit is connected to the input terminal of the first matching circuit, the first signal output terminal of the first matching circuit is connected to the signal input terminal of the 0-phase offset path, the second signal output terminal of the first matching circuit is connected to the signal input terminal of the π / 2-phase offset path, the signal output terminal of the 0-phase offset path is connected to the first signal input terminal of the first antenna, and the signal output terminal of the π / 2-phase offset path is connected to the second signal input terminal of the first antenna. During operation, the first microcontroller generates binary data and transmits it to the phase control unit. The phase control unit first selects the 0-phase offset path, and then... A matching circuit is connected to the first antenna via a 0-phase offset path. By controlling the matching characteristics of the first matching circuit with the 0-phase offset path and the first antenna using binary data, an OOK modulation function is performed to reflect or not reflect the radio frequency signal passing through the first path hst. When reflected, a first set of reflected radio frequency signals is formed, enabling the transmission of binary data. After the binary data transmission is completed, the phase control unit selects a π / 2 phase offset path. The first matching circuit is then connected to the first antenna via the π / 2 phase offset path. By controlling the matching characteristics of the first matching circuit with the π / 2 phase offset path and the first antenna using binary data, an OOK modulation function is performed to reflect or not reflect the radio frequency signal passing through the first path hst. When reflected, a second set of reflected radio frequency signals is formed, enabling the retransmission of binary data.

[0100] The binary data controls the first matching circuit to perform OOK modulation with the matching characteristics of the 0-phase offset path and the first antenna, realizing the reflection or non-reflection of the radio frequency signal passing through the first path hst. Specifically, the radio frequency signal passing through the first path hst enters the terminal device through the first antenna and the 0-phase offset path; when the impedance of the first matching circuit is matched with the 0-phase offset path and the first antenna, the radio frequency signal passing through the first path hst entering the terminal device is not reflected; when the impedance of the first matching circuit is not matched with the 0-phase offset path and the first antenna, the radio frequency signal passing through the first path hst entering the terminal device is reflected into the environment along the 0-phase offset path and the first antenna, forming a first set of reflected radio frequency signals.

[0101] The binary data controls the first matching circuit to perform OOK modulation on the matching characteristics of the π / 2 phase offset path and the first antenna, realizing the reflection or non-reflection of the radio frequency signal passing through the first path hst. Specifically, the radio frequency signal passing through the first path hst enters the terminal device through the first antenna and the π / 2 phase offset path. When the first matching circuit matches the impedance of the π / 2 phase offset path and the first antenna, the radio frequency signal passing through the first path hst entering the terminal device is not reflected. When the first matching circuit does not match the impedance of the π / 2 phase offset path and the first antenna, the radio frequency signal passing through the first path hst entering the terminal device is reflected into the environment along the π / 2 phase offset path and the first antenna, forming a second set of reflected radio frequency signals. The phase difference between the first set of reflected radio frequency signals and the second set of reflected radio frequency signals is π / 2.

[0102] The receiving device includes a second antenna, a second matching circuit, an envelope detector, a reverse detection unit, and a second microcontroller. The signal output terminal of the second antenna is connected to the signal input terminal of the second matching circuit, the signal output terminal of the second matching circuit is connected to the signal input terminal of the envelope detector, the signal output terminal of the envelope detector is connected to the signal input terminal of the reverse detection unit, and the signal output terminal of the reverse detection unit is connected to the signal input terminal of the second microcontroller. During operation, the second antenna is connected to the second matching circuit. The second antenna receives radio frequency (RF) signals from the environment and transmits them to the second matching circuit. The RF signals from the environment include RF signals transmitted via the second path (HSR) and RF signals reflected by the terminal device via the third path (HTR). The second matching circuit transmits the RF signals from the environment... The signal is transmitted to the envelope detector, which performs peak envelope detection on the radio frequency signal transmitted by the second matching circuit to recover a smooth binary signal waveform. The binary signal waveform is then transmitted to the inverse detection unit. The inverse detection unit acquires the received data from the binary signal waveform and determines whether the start bit of the received data is a rising edge or a falling edge. If it is a rising edge, the received data is in the same direction as the binary data sent by the terminal device and is transmitted to the second microcontroller. If it is a falling edge, the received data is in the opposite direction to the binary data sent by the terminal device and is inverted and transmitted to the second microcontroller. The second microcontroller is connected to the inverse detection unit and receives the received data from the inverse detection unit, completing the communication process between the terminal device and the receiving device.

[0103] The phase control unit first selects a 0-phase offset path. The first matching circuit is connected to the first antenna through the 0-phase offset path. By controlling the matching characteristics of the first matching circuit with the 0-phase offset path and the first antenna through binary data, the OOK modulation function is performed to realize the reflection or non-reflection of the radio frequency signal passing through the first path hst. Specifically, it includes: 1) Selecting a 0-phase offset path and controlling the matching characteristics of the first matching circuit with the 0-phase offset path and the first antenna through binary data B(n), thereby controlling the reflection or non-reflection of the radio frequency signal entering the terminal device through the first path hst.

[0104] 2) When the binary data that the terminal device needs to send is 1, the terminal device is controlled to reflect the radio frequency signal. At this time, the radio frequency signal generated by the radio frequency signal source is reflected through the first path hst and the first antenna and 0 phase offset path in the terminal device to form the first set of reflected radio frequency signals. The first set of reflected radio frequency signals is as shown in formula (2):

[0105]

[0106] Where: x1(t) is the first group of reflected radio frequency signals; The phase value of the first group of reflected radio frequency signals at the first antenna position of the terminal device. It exhibits periodicity with a period of 2π; ηα hst A represents the amplitude of the radio frequency signal received by the receiving device from the terminal device; η is the reflection coefficient of the terminal device, which represents the signal attenuation intensity after the radio frequency signal is reflected by the terminal device; α hst α is the attenuation coefficient of the radio frequency signal on the first path hst. hst B(n) represents the signal attenuation strength of the radio frequency signal after passing through the first path hst, and B(n) represents the binary data sent by the terminal device.

[0107] 3) When the binary data that the terminal device needs to send is 0, the terminal device does not reflect radio frequency signals.

[0108] The phase control unit then selects a π / 2 phase offset path. The first matching circuit is connected to the first antenna via the π / 2 phase offset path. By controlling the matching characteristics of the first matching circuit with the π / 2 phase offset path and the first antenna using binary data, an OOK modulation function is performed to achieve the reflection or non-reflection of the RF signal passing through the first path hst. Specifically, this includes:

[0109] 1) Select the π / 2 phase offset path and control the matching characteristics of the first matching circuit with the π / 2 phase offset path and the first antenna through binary data B(n), thereby controlling the reflection or non-reflection of the RF signal entering the terminal device through the first path hst;

[0110] 2) When the binary data that the terminal device needs to send is 1, the radio frequency signal generated by the radio frequency signal source is reflected by the first path hst and the first antenna and π / 2 phase offset path in the terminal device to form a second set of reflected radio frequency signals. The second set of reflected radio frequency signals is shown in formula (3):

[0111]

[0112] Where: x2(t) is the second set of reflected radio frequency signals; The phase value of the second set of reflected radio frequency signals at the first antenna position of the terminal device. It exhibits periodicity with a period of 2π; ηα hst A represents the amplitude of the radio frequency signal received by the receiving device from the terminal device; η is the reflection coefficient of the terminal device, which represents the signal attenuation intensity after the radio frequency signal is reflected by the terminal device; α hst Let α be the attenuation coefficient of the source signal on the first path hst. hst B(n) represents the signal attenuation strength of the radio frequency signal after passing through the first path hst, and B(n) represents the binary data sent by the terminal device.

[0113] 3) When the binary data that the terminal device needs to send is 0, the terminal device does not reflect the radio frequency signal; after the π / 2 phase offset path has finished sending the binary data, the terminal device completes the data transmission.

[0114] When the terminal device reflects a radio frequency (RF) signal, the receiving device receives the superposition of the RF signal generated by the RF signal source in the environment and the reflected RF signal from the terminal device. When the terminal device does not reflect a RF signal, the receiving device receives the RF signal generated by the RF signal source in the environment. The reflected RF signal is either a first set of reflected RF signals or a second set of reflected RF signals. When the receiving device receives the superposition of the RF signal generated by the RF signal source in the environment and the first set of reflected RF signals from the terminal device, the RF signal generated by the RF signal source and the first set of reflected RF signals from the terminal device are superimposed to form a first set of RF signals. When the receiving device receives the superposition of the RF signal generated by the RF signal source in the environment and the second set of reflected RF signals from the terminal device, the RF signal generated by the RF signal source and the second set of reflected RF signals from the terminal device are superimposed to form a second set of RF signals.

[0115] The waveform function of the first group of radio frequency signals includes the radio frequency signal generated by the radio frequency signal source and the first group of reflected radio frequency signals reflected by the terminal device through the 0 phase offset path; the waveform function of the first group of radio frequency signals is shown in formula (4):

[0116]

[0117] Where: y1(t) is the first group of radio frequency signals; α hsr A represents the amplitude of the radio frequency signal received by the receiving device from the radio frequency signal source; α hsr α is the source signal attenuation coefficient on the second path hsr. hsr ηα represents the signal attenuation intensity of the radio frequency signal after passing through the second path HSR. hst α htr A represents the amplitude of the radio frequency signal reflected from the terminal device received by the receiving device; α htr α is the source signal attenuation coefficient on the third path htr. htr η represents the signal attenuation intensity of the radio frequency signal after passing through the third path htr; η is the reflection coefficient of the terminal device; θ is the phase value of the radio frequency signal received by the receiving device from the radio frequency signal source. The phase value of the first set of reflected radio frequency signals received by the receiving device from the terminal device; The phase deviation is the difference between the first set of reflected radio frequency signals received by the receiving device from the terminal device and the radio frequency signals generated by the radio frequency signal source; phase deviation It is periodic with a period of 2π; B(n) is the binary data sent by the terminal device.

[0118] The waveform function of the second set of radio frequency signals includes the radio frequency signal generated by the radio frequency signal source and the second set of reflected radio frequency signals reflected by the terminal device through the π / 2 phase offset path; the waveform function of the second set of radio frequency signals is shown in formula (5):

[0119]

[0120] Where: y2(t) is the second group of radio frequency signals; α hsr A represents the amplitude of the radio frequency signal received by the receiving device from the radio frequency signal source; α hsr α is the attenuation coefficient of the source signal on the second path HSR. hsr ηα represents the signal attenuation intensity of the radio frequency signal after passing through the second path, hsr; hst α htr A represents the amplitude of the radio frequency signal reflected from the terminal device received by the receiving device; α htr α is the attenuation coefficient of the source signal on the third path htr. htr θ represents the signal attenuation intensity of the radio frequency signal after passing through the third path htr; θ is the phase value of the radio frequency signal received by the receiving device from the signal source. The phase value of the second set of reflected radio frequency signals received by the receiving device from the terminal device; The phase deviation between the second set of reflected radio frequency signals received by the receiving device from the terminal device and the radio frequency signals received from the radio frequency signal source; phase deviation It exhibits periodicity with a period of 2π; B(n) represents the valid binary data of the terminal device; This indicates that the phase difference between the first group of radio frequency signals and the second group of radio frequency signals is...

[0121] The workflow of the receiving device includes:

[0122] 1) In the environmental backscatter communication system, the receiving equipment first receives the first set of radio frequency signals.

[0123] If the transmitted data in the binary data sent by the terminal device is 0, and B(n) = 0, then the terminal device does not reflect the radio frequency signal. At this time, the first set of radio frequency signals received by the receiving device is as shown in formula (6):

[0124] y1(t)=α hsr Acos(ωt+θ) (6);

[0125] If the binary data sent by the terminal device contains 1 and B(n) = 1, then the radio frequency signal is reflected. At this time, the first set of radio frequency signals received by the receiving device is as shown in formula (7):

[0126]

[0127] Perform the transformation operation on formula (7) as shown in formula (8) - formula (10):

[0128]

[0129]

[0130] y1(t)=K1(cos(ωt+θ)cosγ1-sin(ωt+θ)sinγ1)=K1cos(ωt+θ+γ1) (10);

[0131] in:

[0132]

[0133]

[0134]

[0135] K1 represents the superimposed amplitude of the radio frequency signal received by the receiving device from the radio frequency signal source and the first set of reflected radio frequency signals reflected by the terminal device through the 0 phase offset path, i.e., the amplitude of the first set of radio frequency signals.

[0136] Let the amplitudes of the radio frequency signals in formulas (6) and (10) be equal, and find the phase position where the amplitude of the first set of radio frequency signals is equal to the amplitude of the radio frequency signal from the radio frequency signal source, as shown in formula (11):

[0137] α hsr A = K1 (11);

[0138] Perform the transformation operation on formula (11) as shown in formula (12) - formula (16):

[0139]

[0140]

[0141]

[0142]

[0143] or

[0144] At this time, if or Then K1>α hsr A, The amplitude K1 of the first group of radio frequency signals is greater than the amplitude α of the radio frequency signal generated only from the radio frequency signal source. hsr A. The envelope detector detects the first group of radio frequency signals and recovers the waveform of the first group of binary signals. The reverse detection unit samples the waveform of the first group of binary signals and recovers the first group of binary 01 data. The first data waveform is detected as a rising edge. At this time, the binary data sent by the terminal device is in the same direction as the first group of binary 01 data recovered by the reverse detection unit, and the binary data sent by the terminal device can be obtained directly.

[0145] like Then K1 < α hsr A, the amplitude K1 of the first group of radio frequency signals is less than the amplitude α of the radio frequency signal generated only from the radio frequency signal source. hsr A. The envelope detector detects the first group of radio frequency signals and recovers the waveform of the first group of binary signals. The reverse detection unit samples the waveform of the first group of binary signals and recovers the first group of binary 01 data. The first data waveform is detected as a falling edge. At this time, the binary data sent by the terminal device is the reverse of the first group of binary 01 data recovered by the reverse detection unit. The binary data transmitted by the terminal device is obtained by inverting the first group of binary 01 data recovered by the reverse detection unit. The data inversion means changing the 0 in the binary 01 data recovered by the reverse detection unit to 1 and the 1 to 0.

[0146] like or Then K1 = α hsr A, the amplitude K1 of the first group of radio frequency signals is equal to the amplitude α of the radio frequency signal generated only from the radio frequency signal source. hsr A. The envelope detector detects the first group of radio frequency signals and recovers the waveform of the first group of binary signals. The reverse detection unit samples the binary signal waveform and recovers the first group of binary signal waveforms, which are all 0s. It is impossible to distinguish whether it is a rising edge or a falling edge, and therefore it is impossible to recover the binary data transmitted by the terminal device. The closer or When the difference between the waveforms of 0 and 1 data is smaller, an extremely small threshold is needed to distinguish between 0 and 1 data, and the smaller the threshold, the higher the bit error rate of the data; at this time, it is necessary to receive a second set of radio frequency signals for judgment.

[0147] 2) In the environmental backscatter communication system, if the second set of radio frequency signals is received by the receiving device, and the transmitted data in the binary data sent by the terminal device is 0, B(n) = 0, then the terminal device does not reflect the radio frequency signal. At this time, the second set of radio frequency signals received by the receiving device is as shown in formula (17):

[0148] y2(t)=α hsr Acos(ωt+θ) (17);

[0149] If the binary data sent by the terminal device contains 1 and B(n) = 1, then the reflected radio frequency signal will be received by the receiving device as shown in formula (18):

[0150]

[0151] Perform the transformation operation on formula (18) as shown in formula (19) - formula (22):

[0152]

[0153]

[0154]

[0155] y2(t)=K2(cos(ωt+θ)cosγ2-sin(ωt+θ)sinγ2)=K2cos(ωt+θ+γ2) (22);

[0156] in:

[0157]

[0158]

[0159]

[0160] K2 represents the superposition amplitude of the radio frequency signal received by the receiving device and the second set of reflected radio frequency signals reflected by the terminal device through the π / 2 phase offset path, i.e., the amplitude of the second set of radio frequency signals;

[0161] The amplitude of the radio frequency signal received by the receiving device and generated by the radio frequency signal source is compared with that of the second group of radio frequency signals:

[0162] K2 represents the amplitude of the second group of radio frequency signals, α hsr A represents the amplitude of the radio frequency signal generated from the radio frequency signal source, therefore K2 and α hsr A is greater than 0;

[0163]

[0164]

[0165]

[0166]

[0167]

[0168] like

[0169]

[0170] Because the backscattering from the second path (hsr) is less than the sum of the first path (hst) and the third path (htr), and the reflection coefficient of the terminal device (η) is less than 1, the amplitude α of the radio frequency signal reaching the receiving device through the second path (hsr) is... hsr A is definitely greater than the amplitude ηα of the radio frequency signal that reaches the receiving device after passing through the first path hst, the third path htr, and the reflection from the terminal device. hst α htr A, therefore

[0171]

[0172] therefore K2 represents the amplitude of the second group of radio frequency signals, α hsr A represents the amplitude of the radio frequency signal generated from the radio frequency signal source, therefore K2 and α hsr If A is greater than 0, then K2 < α hsr A, the amplitude K2 of the second group of radio frequency signals is less than the amplitude α of the radio frequency signal generated only from the radio frequency signal source. hsrA. The envelope detector detects the second group of radio frequency signals and recovers the waveform of the second group of binary signals. The reverse detection unit samples the waveform of the second group of binary signals and recovers the second group of binary 01 data. The first data waveform is detected as a falling edge. At this time, the binary data sent by the terminal device is the inverse of the second group of binary 01 data recovered by the reverse detection unit. The binary data transmitted by the terminal device is obtained by inverting the second group of binary 01 data recovered by the reverse detection unit.

[0173] like

[0174]

[0175]

[0176] Because the backscattering from the second path (hsr) is less than the sum of the first path (hst) and the third path (htr), and the reflection coefficient of the terminal device (η) is less than 1, the amplitude α of the radio frequency signal reaching the receiving device through the second path (hsr) is... hsr A is definitely greater than the amplitude ηα of the radio frequency signal that reaches the receiving device after passing through the first path hst, the third path htr, and the reflection from the terminal device. hst α htr A, therefore

[0177]

[0178] therefore, K2 and α hsr If A is greater than 0, then K2 > α hsr A, The amplitude K2 of the second group of radio frequency signals is greater than the amplitude α of the radio frequency signal generated only from the radio frequency signal source. hsr A. The envelope detector detects the second group of radio frequency signals and recovers the waveform of the second group of binary signals. The reverse detection unit samples the waveform of the second group of binary signals and recovers the second group of binary 01 data. It detects that the first data waveform is a rising edge. At this time, the binary data sent by the terminal device is in the same direction as the second group of binary 01 data recovered by the reverse detection unit, and the binary data sent by the terminal device can be obtained directly.

[0179] This invention increases the data threshold of the receiving device and reduces the bit error rate of the communication system by adding a second set of reflected radio frequency signals with a phase deviation of π / 2.

[0180] The present invention addresses the phase deviation between the first set of reflected radio frequency signals received by the receiving device and the radio frequency signals generated by the radio frequency signal source received by the receiving device. arrive Between these two groups, the amplitude K1 of the first group of radio frequency signals is less than the amplitude α of the radio frequency signals generated solely from the radio frequency signal source. hsr A. When terminal transmission data cannot be obtained, reverse data detection is added to invert the reverse data and recover the data transmitted by the terminal device; the phase deviation between the first set of reflected radio frequency signals received by the receiving device and the radio frequency signals generated by the radio frequency signal source received by the receiving device. or When terminal transmission data cannot be obtained, the terminal transmission data can be correctly obtained by adding a second set of reflected radio frequency signals with a phase deviation of π / 2.

Claims

1. An environmental backscatter communication system based on phase deviation reconstruction, characterized in that: Includes a radio frequency signal source, terminal equipment, and receiving equipment; the radio frequency signal source, on the one hand, passes through the first path The radio frequency signal is transmitted to the terminal device, and on the other hand, it is transmitted via a second path. The radio frequency signal is transmitted to the receiving device; the terminal device selects the path through the first path according to the binary data to be transmitted. The transmitted radio frequency signal passes through a third path The image may be reflected to the receiving device or not; the receiving device may reflect to the receiving device via the second path. Transmitted radio frequency signals and via a third path The radio frequency signals reflected by the transmitting terminal equipment are superimposed and detected by an envelope detector to recover the binary signal waveform; The terminal device includes a first microcontroller, a phase control unit, a first matching circuit, and a zero-phase offset path. Phase offset path, first antenna; the signal output terminal of the first microcontroller is connected to the signal input terminal of the phase control unit, the output terminal of the phase control unit is connected to the input terminal of the first matching circuit, the first signal output terminal of the first matching circuit is connected to the signal input terminal of the 0 phase offset path, and the second signal output terminal of the first matching circuit is connected to... The signal input terminal of the phase-offset path is connected, and the signal output terminal of the 0-phase-offset path is connected to the first signal input terminal of the first antenna. The signal output terminal of the phase offset path is connected to the second signal input terminal of the first antenna. During operation, the first microcontroller generates binary data and transmits it to the phase control unit. The phase control unit first selects the 0-phase offset path. The first matching circuit connects to the first antenna via the 0-phase offset path and uses the binary data to control the matching characteristics of the first matching circuit with the 0-phase offset path and the first antenna to perform OOK modulation, thereby achieving the desired signal output from the first antenna. The radio frequency signal is reflected or not reflected. When reflected, the first set of reflected radio frequency signals is formed, enabling the transmission of binary data. After the binary data transmission is complete, the phase control unit then selects... Phase offset path, the first matching circuit passes through The phase offset path is connected to the first antenna and controls the first matching circuit by transmitting binary data. The phase offset path and the matching characteristics of the first traverse antenna are subjected to OOK modulation function to achieve the effect of the first path. The radio frequency signal may or may not be reflected. When it is reflected, a second set of reflected radio frequency signals is formed, which enables the retransmission of binary data. The receiving device includes a second antenna, a second matching circuit, an envelope detector, a reverse detection unit, and a second microcontroller. The signal output terminal of the second antenna is connected to the signal input terminal of the second matching circuit; the signal output terminal of the second matching circuit is connected to the signal input terminal of the envelope detector; the signal output terminal of the envelope detector is connected to the signal input terminal of the reverse detection unit; and the signal output terminal of the reverse detection unit is connected to the signal input terminal of the second microcontroller. During operation, the second antenna is connected to the second matching circuit. The second antenna receives radio frequency signals from the environment and transmits them to the second matching circuit. These radio frequency signals include those transmitted via a second path. The transmitted radio frequency signals and terminal equipment are transmitted via a third path. The reflected radio frequency (RF) signal is transmitted from the environment to the envelope detector via the second matching circuit. The envelope detector performs peak envelope detection on the RF signal transmitted from the environment by the second matching circuit, recovers the binary signal waveform, and transmits the binary signal waveform to the inverse detection unit. The inverse detection unit acquires the received data from the binary signal waveform and determines whether the start bit of the received data is a rising edge or a falling edge. If it is a rising edge, the received data is in the same direction as the binary data sent by the terminal device and is transmitted to the second microcontroller. If it is a falling edge, the received data is in the opposite direction to the binary data sent by the terminal device and is inverted and transmitted to the second microcontroller. The second microcontroller is connected to the inverse detection unit and receives the received data from the inverse detection unit, completing the communication process between the terminal device and the receiving device.

2. The environmental backscatter communication system based on phase deviation reconstruction according to claim 1, characterized in that: The radio frequency signal generated by the radio frequency signal source is as shown in formula (1): （1）； in: This refers to the radio frequency signal generated by the radio frequency signal source. Indicates the amplitude of the radio frequency signal. , ω represents angular velocity, and T and f represent the period and frequency of the radio frequency signal, respectively.

3. The environmental backscatter communication system based on phase deviation reconstruction according to claim 1, characterized in that: The binary data controls the first matching circuit to perform OOK modulation with the matching characteristics of the 0-phase offset path and the first antenna, thereby enabling the modulation of the circuit through the first path. The reflection or non-reflection of radio frequency signals, specifically including: the reflection or non-reflection of signals passing through the first path. The radio frequency signal enters the terminal device through the first antenna and the 0-phase offset path; when the first matching circuit matches the impedance of the 0-phase offset path and the first antenna, the signal entering the terminal device passes through the first path... The radio frequency signal is not reflected; when the first matching circuit is mismatched with the 0-phase offset path and the impedance of the first antenna, the signal entering the terminal device is reflected through the first path. The radio frequency signal is reflected into the environment along a 0-phase offset path by the first antenna, forming a first set of reflected radio frequency signals; the binary data controls the first matching circuit and... The phase offset path and the matching characteristics of the first traverse antenna are subjected to OOK modulation function to achieve the effect of the first path. The reflection or non-reflection of radio frequency signals, specifically including: the reflection or non-reflection of signals passing through the first path. The radio frequency signal passes through the first antenna and The phase offset path enters the terminal device, when the first matching circuit and When the phase offset path and the first antenna impedance are matched, the path leading to the terminal device is the first path. The radio frequency signal is not reflected; the first matching circuit and When the phase offset path and the impedance of the first antenna are mismatched, the signal entering the terminal device will pass through the first path. radio frequency signal along The phase-shifted path and the reflection from the first antenna into the environment form a second set of reflected radio frequency signals; the phase difference between the first set of reflected radio frequency signals and the second set of reflected radio frequency signals is... .

4. The environmental backscatter communication system based on phase deviation reconstruction according to claim 1, characterized in that: The phase control unit first selects a 0-phase offset path. The first matching circuit is connected to the first antenna via the 0-phase offset path. It then uses binary data to control the matching characteristics of the first matching circuit with the 0-phase offset path and the first antenna to perform OOK modulation, thereby achieving the desired effect for the antenna passing through the first path. The reflection or non-reflection of radio frequency signals, specifically including: 1) When the binary data that the terminal device needs to send is 1, the terminal device is controlled to reflect the radio frequency signal. At this time, the radio frequency signal generated by the radio frequency signal source passes through the first path. After being reflected by the first antenna and the 0-phase offset path in the terminal equipment, the first set of reflected radio frequency signals is formed, as shown in formula (2): （2）； in: This is the first group of reflected radio frequency signals; The phase value of the first group of reflected radio frequency signals at the first antenna position of the terminal device. It is periodic, with a period of 1 / 2. ; This indicates the amplitude of the radio frequency signal reflected from the terminal device received by the receiving device; The reflectance of the terminal device. This represents the signal attenuation intensity of the radio frequency signal after it is reflected by the terminal device. For the first path Attenuation coefficient of radio frequency signal, This indicates that the radio frequency signal has passed through the first path. The signal attenuation strength after the signal is transmitted, B(n) represents the binary data sent by the terminal device; 2) When the binary data that the terminal device needs to send is 0, the terminal device does not reflect radio frequency signals; The phase control unit selects again Phase offset path, the first matching circuit passes through The phase offset path is connected to the first antenna, and controls the first matching circuit by transmitting binary data. The phase offset path and the matching characteristics of the first traverse antenna are subjected to OOK modulation to achieve the function of modulation of the phase offset path and the first traverse antenna. The reflection or non-reflection of radio frequency signals, specifically including: 3) When the binary data that the terminal device needs to send is 1, At this time, the radio frequency signal generated by the radio frequency signal source passes through the first path. and through the first antenna in the terminal equipment, After reflection along the phase-shifted path, a second set of reflected radio frequency signals is formed, as shown in formula (3): （3）； in: This is the second set of reflected radio frequency signals; The phase value of the second set of reflected radio frequency signals at the first antenna position of the terminal device. It is periodic, with a period of 1 / 2. ; This indicates the amplitude of the radio frequency signal reflected from the terminal device received by the receiving device; The reflectance of the terminal device. This represents the signal attenuation intensity of the radio frequency signal after it is reflected by the terminal device. For the first path Attenuation coefficient of source signal, This indicates that the radio frequency signal has passed through the first path. The signal attenuation strength after the signal is transmitted, B(n) represents the binary data sent by the terminal device; 4) When the binary data that the terminal device needs to send is 0, the terminal device does not reflect radio frequency signals; After the phase offset path has finished sending the binary data, the terminal device has completed the data transmission.

5. An environmental backscatter communication system based on phase deviation reconstruction according to claim 1, 3, or 4, characterized in that: When the terminal device reflects a radio frequency signal, the receiving device receives the superposition of the radio frequency signal generated by the radio frequency signal source in the environment and the reflected radio frequency signal of the terminal device; When the terminal device does not reflect radio frequency signals, the receiving device receives radio frequency signals generated by radio frequency signal sources in the environment; the reflected radio frequency signals are either a first set of reflected radio frequency signals or a second set of reflected radio frequency signals. When the receiving device receives the superposition of the radio frequency signal generated by the radio frequency signal source in the environment and the first set of reflected radio frequency signals of the terminal device, the radio frequency signal generated by the radio frequency signal source and the first set of reflected radio frequency signals of the terminal device are superimposed to form the first set of radio frequency signals; When the receiving device receives the superposition of the radio frequency signal generated by the radio frequency signal source in the environment and the second set of reflected radio frequency signals of the terminal device, the radio frequency signal generated by the radio frequency signal source and the second set of reflected radio frequency signals of the terminal device are superimposed to form the second set of radio frequency signals.

6. An environmental backscatter communication system based on phase deviation reconstruction according to claim 5, characterized in that: The waveform function of the first group of radio frequency signals includes the radio frequency signal generated by the radio frequency signal source and the first group of reflected radio frequency signals reflected by the terminal device through the 0 phase offset path; the waveform function of the first group of radio frequency signals is shown in formula (4): （4）； in: This is the first group of radio frequency signals; This indicates the amplitude of the radio frequency signal received by the receiving device from the radio frequency signal source; For the second path The source signal attenuation coefficient on the signal, This indicates that the radio frequency signal has passed through the second path. The intensity of signal attenuation after the signal is applied; This indicates the amplitude of the radio frequency signal reflected from the terminal device received by the receiving device; For the third path The source signal attenuation coefficient on the signal, This indicates that the radio frequency signal has passed through a third path. The intensity of signal attenuation after the signal is applied; The reflection coefficient of the terminal device; The phase value of the radio frequency signal received by the receiving device from the radio frequency signal source; The phase value of the first set of reflected radio frequency signals received by the receiving device from the terminal device; The phase deviation is the difference between the first set of reflected radio frequency signals received by the receiving device from the terminal device and the radio frequency signals generated by the radio frequency signal source; phase deviation It is periodic, with a period of 1 / 2. B(n) represents the binary data sent by the terminal device.

7. An environmental backscatter communication system based on phase deviation reconstruction according to claim 5, characterized in that: The waveform function of the second group of radio frequency signals includes the radio frequency signals generated by the radio frequency signal source and the signals transmitted by the terminal device. The second set of reflected RF signals is reflected through the phase offset path; the waveform function of the second set of RF signals is shown in formula (5): （5）； in: This is the second group of radio frequency signals; This indicates the amplitude of the radio frequency signal received by the receiving device from the radio frequency signal source; For the second path Attenuation coefficient of source signal, This indicates that the radio frequency signal has passed through the second path. The signal attenuation intensity afterward; This indicates the amplitude of the radio frequency signal reflected from the terminal device received by the receiving device; For the third path Attenuation coefficient of source signal, This indicates that the radio frequency signal has passed through a third path. The signal attenuation intensity afterward; The phase value of the radio frequency signal received by the receiving device from the signal source; The phase value of the second set of reflected radio frequency signals received by the receiving device from the terminal device; The phase deviation between the second set of reflected radio frequency signals received by the receiving device from the terminal device and the radio frequency signals received from the radio frequency signal source; phase deviation It is periodic, with a period of 1 / 2. B(n) represents the valid binary data of the terminal device; This indicates that the phase difference between the first group of radio frequency signals and the second group of radio frequency signals is... .

8. An environmental backscatter communication system based on phase deviation reconstruction according to claim 5, characterized in that: The workflow of the receiving device includes: 1) In the environmental backscatter communication system, the receiving equipment first receives the first set of radio frequency signals. If the transmitted data in the binary data sent by the terminal device is 0, and B(n) = 0, then the terminal device does not reflect the radio frequency signal. At this time, the first set of radio frequency signals received by the receiving device is as shown in formula (6): （6）； If the binary data sent by the terminal device contains 1 and B(n) = 1, then the radio frequency signal is reflected. At this time, the first set of radio frequency signals received by the receiving device is as shown in formula (7): （7）； Perform the transformation operation on formula (7) as shown in formula (8) - formula (10): （8）； （9）； （10）； in: ; This represents the superimposed amplitude of the radio frequency signal received by the receiving device from the radio frequency signal source and the first set of reflected radio frequency signals reflected by the terminal device through the 0-phase offset path, i.e., the amplitude of the first set of radio frequency signals; Let the amplitudes of the radio frequency signals in formulas (6) and (10) be equal, and find the phase position where the amplitude of the first set of radio frequency signals is equal to the amplitude of the radio frequency signal from the radio frequency signal source, as shown in formula (11): （11）； Perform the transformation operation of formula (11) as shown in formula (12) - formula (16): （12）； （13）； （14）； （15）； （16）； At this time, if or ,but The amplitude of the first group of radio frequency signals Greater than the amplitude of the radio frequency signal generated solely from the radio frequency signal source. The envelope detector detects the first group of radio frequency signals and recovers the waveform of the first group of binary signals. The reverse detection unit samples the waveform of the first group of binary signals and recovers the first group of binary 01 data. The first data waveform is detected as a rising edge. At this time, the binary data sent by the terminal device is in the same direction as the first group of binary 01 data recovered by the reverse detection unit, and the binary data sent by the terminal device can be obtained directly. like ,but The amplitude K1 of the first group of radio frequency signals is less than the amplitude of the radio frequency signals generated only from the radio frequency signal source. The envelope detector detects the first group of radio frequency signals and recovers the waveform of the first group of binary signals. The reverse detection unit samples the waveform of the first group of binary signals and recovers the first group of binary 01 data. The first data waveform is detected as a falling edge. At this time, the binary data sent by the terminal device is the reverse of the first group of binary 01 data recovered by the reverse detection unit. The binary data transmitted by the terminal device is obtained by inverting the first group of binary 01 data recovered by the reverse detection unit. The data inversion means changing the 0 in the binary 01 data recovered by the reverse detection unit to 1 and the 1 to 0. like or ,but The amplitude of the first group of radio frequency signals Equal to the amplitude of the radio frequency signal generated only by the radio frequency signal source The envelope detector detects the first set of radio frequency signals and recovers the waveform of the first set of binary signals. The reverse detection unit samples the waveform of the binary signals and recovers the first set of binary signals, which are all 0s. It is impossible to distinguish whether it is a rising edge or a falling edge, and it is impossible to recover the binary data transmitted by the terminal device. At this time, it is necessary to receive the second set of radio frequency signals for judgment. 2) In the environmental backscatter communication system, if the second set of radio frequency signals is received by the receiving device, and the transmitted data in the binary data sent by the terminal device is 0, B(n)=0, then the terminal device does not reflect the radio frequency signal. At this time, the second set of radio frequency signals received by the receiving device is as shown in formula (17): （17）； If the binary data sent by the terminal device contains a 1, and B(n) = 1, then the reflected radio frequency signal will be received by the receiving device as shown in formula (18): （18）； Perform the transformation operation of formula (18) as shown in formula (19) - formula (22): （19）； （20）； （21）； （22）； in: ； ； ； This indicates that the radio frequency signal received by the receiving device is generated by the radio frequency signal source and transmitted through the terminal device. The superimposed amplitude of the second set of reflected radio frequency signals reflected by the phase offset path, i.e., the amplitude of the second set of radio frequency signals; The amplitude of the radio frequency signal received by the receiving device and generated by the radio frequency signal source is compared with that of the second group of radio frequency signals: This represents the amplitude of the second group of radio frequency signals. This represents the amplitude of the radio frequency signal generated from the radio frequency signal source, therefore and All are greater than 0; ； ； ； ； ； like , , , ； Due to environmental backscattering second path Less than the first path and the third path The sum of these, and the reflection coefficient of the terminal device. <1, therefore, the second path is followed. The amplitude of the radio frequency signal reaching the receiving device It must be greater than the path taken through the first path. and the third path and the amplitude of the radio frequency signal reflected from the terminal device to the receiving device ,therefore , ， therefore , This represents the amplitude of the second group of radio frequency signals. This represents the amplitude of the radio frequency signal generated from the radio frequency signal source, therefore and Both are greater than 0; then The amplitude of the second group of radio frequency signals Less than the amplitude of the radio frequency signal generated solely from the radio frequency signal source The envelope detector detects the second set of radio frequency signals and recovers the waveform of the second set of binary signals. The reverse detection unit samples the waveform of the second set of binary signals and recovers the second set of binary 01 data. The first data waveform is detected as a falling edge. At this time, the binary data sent by the terminal device is the reverse of the second set of binary 01 data recovered by the reverse detection unit. The binary data transmitted by the terminal device is obtained by inverting the second set of binary 01 data recovered by the reverse detection unit. like , ， ， Due to environmental backscattering second path Less than the first path and the third path The sum of these, and the reflection coefficient of the terminal device. <1, therefore, the second path is followed. The amplitude of the radio frequency signal reaching the receiving device It must be greater than the path taken through the first path. and the third path and the amplitude of the radio frequency signal reflected from the terminal device to the receiving device ,therefore ; , therefore, , and Both are greater than 0; then The amplitude of the second group of radio frequency signals Greater than the amplitude of the radio frequency signal generated solely from the radio frequency signal source. The envelope detector detects the second set of radio frequency signals and recovers the waveform of the second set of binary signals. The reverse detection unit samples the waveform of the second set of binary signals and recovers the second set of binary 01 data. It detects that the first data waveform is a rising edge. At this time, the binary data sent by the terminal device is in the same direction as the second set of binary 01 data recovered by the reverse detection unit, and the binary data sent by the terminal device is directly obtained.

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