CN112468225B

CN112468225B - LoRa backscattering communication method and system

Info

Publication number: CN112468225B
Application number: CN202011263113.2A
Authority: CN
Inventors: 何源; 郭秀珍
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2020-11-12
Filing date: 2020-11-12
Publication date: 2022-02-18
Anticipated expiration: 2040-11-12
Also published as: CN112468225A

Abstract

The present invention provides a LoRa backscatter communication method and system, including: acquiring an ALoba tag; acquiring a LoRa data packet through the ALoba tag; modulating the LoRa data packet by an amplitude keying method to obtain a modulated signal, and The modulated signal is reflected to the LoRa receiver. By designing the backscatter communication system ALoba, the present invention uses the LoRa signal in the environment as the carrier, and the tag modulates the sensing data into an amplitude-keyed modulation signal and mounts it on the carrier to reflect it to the LoRa receiver. The direct LoRa carrier signal and the reflected ALoba sensing signal are simultaneously decoded in the signal, which has the characteristics of flexible link throughput, long-distance transmission, and easy deployment.

Description

LoRa backscattering communication method and system

Technical Field

The invention relates to the technical field of wireless communication, in particular to a LoRa backscattering communication method and system.

Background

The key to the success of industry 4.0 is the realization of ubiquitous, reliable, efficient link connections and data transfer between the underlying machine and machine (M2M).

Different industrial applications, however, have different transmission requirements for data exchange, corresponding to different communication technologies. For example, video-based industrial surveillance scenarios require high throughput (several Gbps) to reduce latency; in contrast, the operational state of the sensing mechanism requires only a medium-sized data rate (several tens of Kbps) to achieve the transfer of the sensing data. However, many mechanical devices may generate strong noise, flash light, or emit harmful gas, and the like, in such a scenario, a forwarding link of sensing data needs to have low power consumption and a long distance, so that the sensing sensor can transmit data to the outside of a factory with a length of hundreds of meters and frequent battery replacement is not needed, and a radio frequency signal is not suitable for directly transmitting such industrial sensing data. Such as 5G and 802.11ax, although low latency transmission can be achieved, the transmission distance is limited; low Power Wide Area Networks (LPWANs), while capable of long-range connectivity, consume a significant amount of energy.

The backscattering communication Backscatter system is more suitable for sensing data transmission of an M2M link due to low power consumption and simple design. However, previous work has not achieved an effective balance between data rate and transmission distance, and only achieved one indication of high data rate or long distance transmission. For example, the data rate of the OFDMA-backscatter system based on Wi-Fi is increased to 5.2Mbps, and only about 10m of communication distance can be supported; in contrast, the PLoRa system based on the LoRa frequency shift can achieve a transmission distance of kilometers level, and a communication rate is only several Kbps.

Disclosure of Invention

The invention provides a LoRa backscattering communication method and a system, which are used for overcoming the defect that the prior art cannot give consideration to both transmission rate and power.

In a first aspect, the present invention provides a method for LoRa backscatter communication, including:

acquiring an ALoba label;

acquiring a LoRa data packet through the ALoba label;

and modulating the LoRa data packet in an amplitude keying mode to obtain a modulation signal, and reflecting the modulation signal to a LoRa receiving end.

Further, the acquiring the ALoba tag specifically includes:

and extracting a plurality of same and continuous upchirp as lead codes to obtain a plurality of equidistant RSS pulses.

Further, the obtaining of the LoRa data packet through the ALoba tag specifically includes:

enabling the plurality of RSS pulses with equal intervals to pass through an analog-to-digital conversion circuit with a preset sampling frequency;

and if a preset number of continuous RSS pulses are detected, acquiring the LoRa data packet.

Further, modulating the LoRa data packet in an amplitude keying manner to obtain a reflection signal specifically includes:

when the lead code is detected, after waiting for the preset LoRa synchronization code element time, the ALoba label modulates the sensing data to a payload part of the LoRa by adopting an amplitude keying mode;

and if the perception data is judged to be 1, the ALoba tag reflects the LoRa data packet to the LoRa receiving end, and if the perception data is judged to be 0, the ALoba tag absorbs the LoRa data packet and does not reflect the LoRa data packet to the LoRa receiving end.

In a second aspect, the present invention further provides a method for LoRa backscatter communication, including:

receiving a modulation signal transmitted by a LoRa transmitting end;

decoding a LoRa direct signal in the modulation signal according to a LoRa decoding algorithm, obtaining conjugate downchirp information from the LoRa direct signal, and obtaining a backscatter reflection signal in the modulation signal based on the conjugate downchirp information;

and decoding label information corresponding to the LoRa data packet by the LoRa direct signal and the backscatter reflected signal.

Further, the decoding a LoRa direct signal in the modulation signal according to a LoRa decoding algorithm, obtaining conjugate downchirp information from the LoRa direct signal, and obtaining a backscatter reflection signal in the modulation signal based on the conjugate downchirp information specifically includes:

converting a plurality of chirp signals with different frequencies into constant sinusoidal signals by adopting conjugate-down chirp;

and reconstructing the constant sinusoidal signal to obtain an amplitude and phase difference sampling point signal.

Further, the tag information corresponding to the LoRa data packet decoded by the LoRa direct signal and the backscatter reflected signal specifically includes:

acquiring the clustering distribution of the amplitude and phase difference sampling point signals on an I-Q plane;

extracting a sampling point containing a reflection signal as a first cluster, wherein the corresponding label data is 1;

and extracting a sampling point which does not contain the reflection signal as a second cluster, wherein the corresponding label data is 0.

In a third aspect, the present invention further provides a LoRa backscatter communication system, including:

the first acquisition module is used for acquiring the ALoba label;

the second acquisition module is used for acquiring the LoRa data packet through the ALoba label;

and the modulation module is used for modulating the LoRa data packet in an amplitude keying mode to obtain a modulation signal and reflecting the modulation signal to a LoRa receiving end.

In a fourth aspect, the present invention further provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the LoRa backscatter communication method according to any one of the above descriptions.

In a fifth aspect, the present invention also provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of the LoRa backscatter communication method as described in any of the above.

According to the LoRa backscattering communication method and system provided by the invention, the backscattering communication system ALoba is designed, the LoRa signal in the environment is used as the carrier, the sensing data is modulated into the amplitude keying modulation signal by the label and is carried on the carrier to be reflected to the LoRa receiving end, and the receiving end can decode the direct LoRa carrier signal and the reflected ALoba sensing signal from the received signal at the same time.

Drawings

In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

Fig. 1 is a schematic flow chart of a LoRa backscatter communication method according to the present invention;

fig. 2 is a technical flowchart of a LoRa backscatter communication method according to the present invention;

FIG. 3 is a schematic diagram of a LoRa packet provided by the present invention;

FIG. 4 is a schematic diagram of a packet detection circuit provided by the present invention;

fig. 5 is a second schematic flow chart of the LoRa backscatter communication method according to the present invention;

FIG. 6 is a schematic diagram of the conversion of a fixed frequency sinusoidal signal provided by the present invention;

FIG. 7 is a schematic diagram of the superposition of the carrier signal and the reflected signal provided by the present invention;

FIG. 8 is a schematic diagram of the phase variation of the received signal provided by the present invention;

fig. 9 is a schematic diagram of signal reconstruction and decoding provided by the present invention;

fig. 10 is a schematic structural diagram of a LoRa backscatter communication system according to the present invention;

fig. 11 is a schematic structural diagram of an electronic device provided in the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Aiming at various defects of the prior art, the invention provides a design and implementation of a backscattering communication method for sensing the state of industrial mechanical equipment, and provides a backscattering communication system ALoba, wherein the ALoba uses a LoRa signal in the environment as a carrier wave, a label modulates sensing data into an amplitude keying modulation signal and carries the amplitude keying modulation signal onto the carrier wave to be reflected to a LoRa receiving end, and the receiving end can decode a direct LoRa carrier signal and a reflected ALoba sensing signal from the received signals at the same time.

The challenges to be solved for implementing the ALoba system include the following two points: (1) unlike conventional RFID systems, there are many radio frequency signals in the environment. Therefore, the ALoba tag needs to find the required LoRa carrier among many wireless signals. The sensing signal is reflected only after the LoRa carrier is detected, so that wrong label awakening and energy waste are avoided; and (2) the signal received by the receiving end is the superposition of the direct LoRa carrier signal and the reflected Aloba signal. Because of the signal attenuation caused by reflectivity and communication distance, the intensity of the reflected signal of the Aloba label is far less than that of the direct LoRa signal. The LoRa receiving end needs to decode a weak Aloba reflected signal from the two paths of superposed signals.

Therefore, the invention innovatively provides a mode of combining software and hardware, the challenges are solved, firstly, a lightweight label is designed, a low-power-consumption LoRa carrier detection circuit is used for detecting LoRa carrier signals from the environment, then, an ALoba label modulates reflected signals to a payload part of a LoRa data packet for transmission, a new decoding algorithm is provided at a LoRa receiving end, the variable-frequency LoRa signals can be converted into sine signals with constant frequency, and the direct LoRa carrier signals and the reflected Aloba signals are decoded simultaneously according to the characteristics of amplitude and phase.

Fig. 1 is a schematic flow diagram of a LoRa backscatter communication method provided by the present invention, and corresponds to a side of a transmitting end, as shown in fig. 1, the method includes:

101, acquiring an ALoba label;

102, acquiring a LoRa data packet through the ALoba label;

103, modulating the LoRa data packet in an amplitude keying manner to obtain a modulation signal, and reflecting the modulation signal to a LoRa receiving end.

Specifically, the present invention adopts an amplitude keying-based LoRa backscatter communication method, wherein a LoRa signal is used as an excitation source to activate a tag, the tag performs amplitude keying on data information, and reflects modulated information to a LoRa receiving end, and a technical flow chart is specifically shown in fig. 2.

According to the invention, the LoRa signal in the environment is used as the carrier, the sensing data is modulated into the modulation signal of the amplitude keying by the label and is carried on the carrier to be reflected to the LoRa receiving end, so that the method has the characteristics of flexible link throughput, long-distance transmission realization and easiness in deployment.

Based on the above embodiment, the obtaining the ALoba tag specifically includes:

Specifically, firstly, the ALoba tag is designed and realized through an LoRa carrier circuit, and an LoRa detection circuit on the tag is designed and realized according to the frequency characteristics of a preamble in an LoRa data packet. As shown in fig. 3 (a), the LoRa preamble is composed of 10 identical consecutive upchirp, the frequency of each upchirp varies linearly with time, and after the received signal passes through a low-pass filter (the cut-off frequency is BW/4, and BW refers to the bandwidth of the LoRa chirp signal), 10 RSS (received signal strength) pulses with equal intervals appear in 10 consecutive upchirp in the original preamble, as shown in fig. 3 (b), such pulses with equal intervals do not appear in the case of noise or other signals. Therefore, the tag can identify the LoRa carrier through the RSS sequence characteristics detected by the LoRa preamble.

The schematic diagram of the data packet detection circuit is shown in fig. 4, a signal firstly passes through a low-power consumption analog-to-digital conversion ADC to obtain a sampling point, and the sampling rate of the ADC is 250 KHz. Because the LoRa supports bandwidths of different frequencies (e.g., 125KHz, 250KHz, and 500KHz), a passband programmable low pass filter is required, a software programmable low pass filter based on moving average is implemented, and the cut-off frequency of the filter can be implemented by setting the size of a moving average window. For example, the window size is 5, and the cut-off frequency of the corresponding filter is 30 KHz. Once the FPGA is able to detect 10 consecutive RSS pulses (amplitude exceeding a certain threshold for other signals), the tag considers that a data packet of LoRa is detected and then switches to modulation mode.

After detecting the preamble of the LoRa, the ALboa tag waits for 2.5 symbol times (corresponding to the synchronization symbol time of the LoRa), and then modulates the sensing data to the payload part of the LoRa in an amplitude keying manner; if the sensing data is 1, the label reflects the LoRa carrier signal to a LoRa receiving end; if the sensing data is 0, the label absorbs the LoRa carrier signal and does not reflect the LoRa carrier signal to a LoRa receiving end. The entire backscatter packet includes four fields, a preamble (010101.. 010101) composed of 16-bit barker codes, a 4-bit rate field for indicating the rate of amplitude keying OOK, an 8-bit length field for indicating the length of payload in the backscatter packet, and the last part is payload.

Fig. 5 is a second schematic flow chart of the LoRa backscatter communication method according to the present invention, and corresponds to the receiving end, as shown in fig. 5, including:

201, receiving a modulation signal transmitted by an LoRa transmitting end;

202, decoding a LoRa direct signal in the modulation signal according to a LoRa decoding algorithm, obtaining conjugate downchirp information from the LoRa direct signal, and obtaining a backscatter reflection signal in the modulation signal based on the conjugate downchirp information;

and 203, decoding the label information corresponding to the LoRa data packet by the LoRa direct signal and the backscatter reflected signal.

Specifically, at the LoRa receiving end, firstly, the LoRa direct signal is decoded by using a LoRa decoding algorithm, and then, the information of conjugate downchirp corresponding to different chirp is obtained according to the decoded LoRa signal, so that the frequency-converted LoRa signal is converted into a sinusoidal signal with constant frequency. And finally, according to the change of the amplitude and the phase of the carrier wave, the receiving end decodes the corresponding label information according to the distribution condition of the received signal on the I-Q plane graph. The technical flow diagram is shown in fig. 2.

Based on the above embodiment, the decoding a LoRa direct signal in the modulated signal according to a LoRa decoding algorithm, obtaining conjugate downchirp information from the LoRa direct signal, and obtaining a backscatter reflected signal in the modulated signal based on the conjugate downchirp information specifically includes:

Specifically, the decoding algorithm of the Aloba is inspired by the decoding algorithm of the traditional RFID system, and the excitation signal source of the RFID system is a sinusoidal signal. Therefore, if the LoRa carrier signal is converted to a sinusoidal signal of constant frequency, the sinusoidal signal is changed by the backscatter transmission signal.

Firstly, converting a frequency conversion chirp signal into a sinusoidal signal with constant frequency, wherein the standard LoRa decoding algorithm multiplies the received different chirp signals by the same down chirp signal (the frequency is changed from BW/2 to-BW/2), so that sine waves with different frequencies can be generated, the frequency of the sine wave is related to the initial frequency of the chirp signal, and the chirp can be decoded according to the frequency of the sine wave. However, at the decoding end of the aloba, the prior standard down-chirp is replaced by a conjugate-down-chirp, as shown in fig. 6, so that it is possible to convert chirp signals of different frequencies into sinusoidal signals of constant frequency.

The converted sinusoidal signal can be considered as a superposition of the direct carrier signal and the tag reflected signal, and two different situations are possible: (1) when the phases of the two signals are aligned or completely opposite (as shown in fig. 7 (b) and fig. 7 (c)), we can directly determine whether there is a reflected signal from the amplitude of the received signal; (2) however, in most cases, the two signals are not aligned (as shown in fig. 7 (a)), and therefore, whether there is a reflected signal or not cannot be directly determined from the change in the amplitude.

In the case of a reflected signal which cannot be determined from the amplitude, the reflected signal is identified from the phase change. When the tag is in the OFF state, the phase of the received signal depends on the phase of the direct signal; when the tag is in the ON reflective state, the phase of the received signal jumps. The phase jump caused by the ON-OFF transition of the tag can be used to detect whether there is a reflected signal, as shown in (a) of fig. 8. However, in addition to this, there are some phase change points which are prone to error and misjudgment, such as where each LoRa is connected to two chirp points, there will be some sudden phase jump (false alarm).

And then phase alignment is carried out according to two steps, and in the first step, phase jump at the joint of the two chirp units is solved. The phase difference between the front and the back of two chirp signals should be a constant value, and the phase change caused by the phase mutation is eliminated according to the actual phase difference and the theoretical phase difference, so that the front and the back chirp signals become continuous, as shown in (b) in fig. 8; and secondly, determining phase points which appear due to frequency inversion in each chirp, wherein the positions can be obtained from decoding results of LoRa on the chirp signals, and phase mutation points corresponding to different chirp signals are fixed. Therefore, the phase jump occurring inside each chirp due to the frequency inversion can also be removed by the method of phase compensation, as shown in (c) of fig. 8.

Further, signal reconstruction and decoding are carried out, the receiving end reconstructs the converted sinusoidal signal, and the reconstructed signal is

Wherein A is_iRepresents the amplitude of the ith sample point;

representing the phase difference between the phase of the ith sample point and the phase of a stable reference sinusoidal signal, as shown in figure 9. And observing the distribution of all the reconstructed sampling points on the I-Q plane, as shown in FIG. 9, it can be easily found that the sampling points are divided into two clusters, one represents that there is a reflection signal, and the other represents that there is no reflection signal. Since each bakcater packet is preceded by 16 barker codes, the two clusters can be determined according to the barker codes, which cluster is decoded by a reflection signal to obtain a tag data of 1, and which cluster is decoded by no reflection signal to obtain a tag data of 0.

It can be understood that there is a certain similarity between the decoding idea of Aloba and the idea of standard LoRa decoding, in which the standard LoRa decoding process multiplies different LoRa chirp by fixed downtirp to convert into sine waves with different frequencies, and decodes data transmitted by chirp symbols by tracking the frequency of the sine waves. However, in the ALoba, the standard down chirp is replaced by the conjugate down chirp, different chirps are all converted into sine waves with the same frequency, and then the backscatter reflected signal is decoded by tracking the amplitude and phase changes, so that the LoRa receiving end can decode both the LoRa direct signal and the backscater reflected signal.

Based on any of the above embodiments, the hardware used in the present invention is specifically: label hardware, loRa sender and loRa receiving terminal, wherein:

the tag hardware comprises three parts, namely a LoRa carrier detection circuit, an FPGA control circuit and an amplitude keying OOK module (realized by a WISP module). The LoRa carrier detection circuit is realized on a single-layer PCB, and separated circuit elements are used. The receive antenna is 3DBi gain with maximum power conversion achieved by optimizing the impedance matching circuit. The FPGA can judge whether the LoRa carrier exists according to the detection result of the carrier detection circuit. And if the carrier signal arrives, the amplitude keying OOK module controls whether to reflect the carrier signal or not according to the sensing data. If the sensing data is 1, reflecting the LoRa carrier signal to a LoRa receiving end; if the sensing data is 0, the LoRa carrier signal is absorbed and not reflected.

In the LoRa transmitting terminal and the LoRa receiving terminal, a Semtech SX1276 chip and a 3dBi gain antenna are carried by a commercial STM32L083RZ circuit board to realize the LoRa transmitting terminal. The LoRa sender sends the LoRa packet on channel 1 at 902.5 MHz. Each Lora packet includes 20 symbols and the transmission power is 20 dbm. The default parameters spreading factor SF, coding rate and bandwidth BW are 7, 1 and 125KHz, respectively. The software radio platform USRP N210 is used as a LoRa receiving end, decoding of the LoRa direct signal and the Aloba label reflection signal is achieved, and the sampling rate is 10 MHz. The LoRa receiving end firstly detects the LoRa signals through a standard LoRa lead code detection algorithm, and locates and decodes the data information of each chirp in the LoRa payload. And then, the LoRa receiving end operates an Aloba decoding algorithm to decode the reflection signal of the label and the corresponding data information.

In the following, the LoRa backscatter communication system provided by the present invention is described, and the LoRa backscatter communication system described below and the LoRa backscatter communication method described above may be referred to in correspondence.

Fig. 10 is a schematic structural diagram of an LoRa backscatter communication system provided in the present invention, and as shown in fig. 10, the LoRa backscatter communication system includes: a first obtaining module 1001, a second obtaining module 1002, and a modulating module 1003, wherein:

the first obtaining module 1001 is used for obtaining an ALoba tag; the second obtaining module 1002 is configured to obtain an LoRa packet through the ALoba tag; the modulation module 1003 is configured to modulate the LoRa data packet in an amplitude keying manner to obtain a modulation signal, and reflect the modulation signal to an LoRa receiving end.

According to the invention, by designing the backscatter communication system ALoba, the LoRa signal in the environment is used as the carrier, the sensing data is modulated into the amplitude keying modulation signal by the label and is carried on the carrier to be reflected to the LoRa receiving end, and the receiving end can decode the direct LoRa carrier signal and the reflected ALoba sensing signal from the received signal at the same time.

Fig. 11 illustrates a physical structure diagram of an electronic device, and as shown in fig. 11, the electronic device may include: a processor (processor)1110, a communication interface (communication interface)1120, a memory (memory)1130, and a communication bus 1140, wherein the processor 1110, the communication interface 1120, and the memory 1130 communicate with each other via the communication bus 1140. Processor 1110 may invoke logic instructions in memory 1130 to perform a LoRa backscatter communication method comprising: acquiring an ALoba label; acquiring a LoRa data packet through the ALoba label; and modulating the LoRa data packet in an amplitude keying mode to obtain a modulation signal, and reflecting the modulation signal to a LoRa receiving end.

In addition, the logic instructions in the memory 1130 may be implemented in software functional units and stored in a computer readable storage medium when sold or used as a stand-alone product. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-only memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

In another aspect, the present invention also provides a computer program product comprising a computer program stored on a non-transitory computer readable storage medium, the computer program comprising program instructions which, when executed by a computer, enable the computer to perform the LoRa backscatter communication method provided by the above methods, the method comprising: acquiring an ALoba label; acquiring a LoRa data packet through the ALoba label; and modulating the LoRa data packet in an amplitude keying mode to obtain a modulation signal, and reflecting the modulation signal to a LoRa receiving end.

In yet another aspect, the present invention also provides a non-transitory computer readable storage medium having stored thereon a computer program that, when executed by a processor, is implemented to perform the LoRa backscatter communication methods provided above, the method comprising: acquiring an ALoba label; acquiring a LoRa data packet through the ALoba label; and modulating the LoRa data packet in an amplitude keying mode to obtain a modulation signal, and reflecting the modulation signal to a LoRa receiving end.

The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. a LoRa backscatter communication method, is characterized in that, comprises:

Get the ALoba label;

Obtain LoRa data packets through the ALoba tag;

The LoRa data packet is modulated by amplitude keying to obtain a modulated signal, and the modulated signal is reflected to the LoRa receiver, so that the LoRa receiver can decode the LoRa in the modulated signal according to the LoRa decoding algorithm. For the direct signal, the conjugate downchirp information is obtained from the LoRa direct signal, and the backscatter reflection signal in the modulated signal is obtained based on the conjugate downchirp information, and the LoRa data packet corresponding to the LoRa direct signal and the backscatter reflection signal is decoded label information.

2. The LoRa backscatter communication method according to claim 1, wherein the acquiring ALoba label specifically comprises:

Extract several identical and continuous upchirps as preambles to obtain several equally spaced RSS pulses.

3. The LoRa backscatter communication method according to claim 2, wherein the acquiring LoRa data packets through the ALoba label specifically includes:

Passing the several equally spaced RSS pulses through an analog-to-digital conversion circuit with a preset sampling frequency;

If a preset number of continuous RSS pulses are detected, the LoRa data packet is acquired.

4. The LoRa backscatter communication method according to claim 2, wherein the described LoRa data packet is modulated by an amplitude keying mode to obtain a reflected signal, specifically comprising:

After the preamble is detected, the ALoba tag waits for the preset LoRa synchronization symbol time, and modulates the sensing data to the payload part of LoRa by using an amplitude keying method;

If it is judged that the sensing data is 1, the ALoba tag reflects the LoRa data packet to the LoRa receiver; if it is judged that the sensing data is 0, the ALoba tag absorbs the LoRa data packet off and not reflected to the LoRa receiver.

5. a LoRa backscatter communication method, is characterized in that, comprises:

Receive the modulated signal transmitted by the LoRa transmitter;

The LoRa direct signal in the modulated signal is decoded according to the LoRa decoding algorithm, the conjugate downchirp information is obtained from the LoRa direct signal, and the backscatter reflection signal in the modulated signal is obtained based on the conjugate downchirp information;

The label information corresponding to the LoRa data packet is decoded from the LoRa direct signal and the backscatter reflected signal.

6. The LoRa backscatter communication method according to claim 5, wherein the LoRa direct signal in the modulated signal is decoded according to the LoRa decoding algorithm, and the conjugate downchirp information is obtained by the LoRa direct signal, Obtaining the backscatter reflection signal in the modulated signal based on the conjugate downchirp information specifically includes:

Use conjugate conjugate-downchirp to convert several chirp signals of different frequencies into constant sinusoidal signals;

The constant sinusoidal signal is reconstructed to obtain amplitude and phase difference sampling point signals.

7. The LoRa backscatter communication method according to claim 6, wherein the label information corresponding to the LoRa data packet is decoded by the LoRa direct signal and the backscatter reflected signal, specifically including:

Obtain the clustering distribution of the amplitude and phase difference sampling point signals in the I-Q plane;

Extract the sampling points containing the reflected signal as the first cluster, and the corresponding label data is 1;

The sampling points that do not contain reflected signals are extracted as the second cluster, and the corresponding label data is 0.

8. A LoRa backscatter communication system, characterized in that, comprising:

The first acquisition module is used to acquire ALoba tags;

The second acquisition module is used to acquire LoRa data packets through the ALoba label;

The modulation module is used to modulate the LoRa data packet by amplitude keying to obtain a modulated signal, and reflect the modulated signal to the LoRa receiver, so that the LoRa receiver can decode the LoRa according to the LoRa decoding algorithm. For the LoRa direct signal in the modulated signal, the conjugate downchirp information is obtained from the LoRa direct signal, and the backscatter reflected signal in the modulated signal is obtained based on the conjugate downchirp information, and the LoRa direct signal and the backscatter reflected signal are obtained. Decode the label information corresponding to the LoRa data packet.

9. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and running on the processor, wherein the processor implements the computer program as claimed in the claims Steps of the LoRa backscatter communication method described in any one of 1 to 7.

10. A non-transitory computer-readable storage medium on which a computer program is stored, characterized in that, when the computer program is executed by a processor, the LoRa backscatter communication according to any one of claims 1 to 7 is realized steps of the method.