A zigbee to lora cross-technology communication method based on physical layer

Abstract

The application relates to a ZigBee-to-Lora cross-technology communication method based on a physical layer, wherein first, a ZigBee terminal encodes target data to be sent to obtain encoded data composed of one of binary numbers 0 or 1, and the encoded data is mapped to form a wireless data transmission signal for sending; then a Lora receiver identifies valid ZigBee data from the received wireless data transmission signal, further obtains corresponding encoded data through identification of a corresponding Fourier spectrum diagram; finally, the Lora receiver decodes and identifies the obtained encoded data according to the encoding rule of the ZigBee terminal, and obtains target data from the ZigBee terminal; the design method completes long-distance communication from the ZigBee terminal to the Lora receiver without the aid of an additional gateway, realizes efficient cross-technology communication, saves the hardware cost in an Internet of Things system, and improves the deployment speed of an Internet of Things data acquisition system.

Description

TECHNICAL FIELD

[0001] The application relates to a ZigBee-to-Lora cross-technology communication method based on a physical layer and belongs to the technical field of cross-technology communication. BACKGROUND

[0002] With the development and popularization of the Internet of Things technology, more and more Internet of Things devices need to be connected to the human network, and the mobile networks commonly used in our life are mainly 2G, 3G, 4G, 5G and the like, although the mobile cellular network has a relatively wide coverage, it is not suitable for being used as an access site of the Internet of Things devices. Secondly, with the development of mobile intelligent products, more and more mobile intelligent products (mobile phones, iPads and mobile computers) need to be connected to the mobile cellular network, which puts a high challenge on the bearing capacity of the mobile cellular network.

[0003] The emergence of the LPWAN (Low Power Wide Area Network) well fills the deficiency of the mobile cellular network for the Internet of Things devices, wherein the Lora is a kind of long-distance low-power communication means widely applied in recent years and belongs to the LPWAN. The Lora is very suitable for being used as a communication base station in the Internet of Things system due to its long-distance, low-power and low-cost advantages, but in the common Internet of Things data collection system, multiple protocols such as ZigBee, WiFi and BLE are often involved, and the common use of multiple communication protocols is often difficult to avoid, which needs to add an additional gateway to send the data in the Internet of Things data collection system to the remote end through the base station, and the addition of the gateway increases the deployment cost of the Internet of Things system and also increases the complexity of the system. SUMMARY

[0004] The application aims to solve the technical problem of providing a ZigBee-to-Lora cross-technology communication method based on a physical layer, which can complete the long-distance communication of the ZigBee terminal to the Lora receiver without the help of an additional gateway and realize efficient cross-technology communication.

[0005] The application adopts the following technical scheme to solve the above technical problem: the application designs a ZigBee-to-Lora cross-technology communication method based on a physical layer, and the following steps A to D are executed in real time to realize the real-time communication of the ZigBee terminal to the Lora receiver.

[0006] Step A. The ZigBee terminal encodes the target data to be sent at the current time according to a preset encoding rule, obtains the corresponding encoded data composed of one of binary number 0 or binary number 1, and maps the encoded data to the corresponding preset rule special sequence based on the preset mapping relationship between the encoded data and the preset rule special sequence, to form a wireless data transmission signal of the ZigBee terminal at the current time, and sends the signal to the Lora receiver, and then enters step B.

[0007] Step B. The Lora receiver applies an identification template for identifying and detecting ZigBee signals to the waveform of the wireless data transmission signal received from the ZigBee terminal, to identify and detect whether there is valid ZigBee data in the wireless data transmission signal, and if so, enters step C; otherwise, the processing of the wireless data transmission signal is abandoned.

[0008] Step C. The Lora receiver performs Fourier transform on the wireless data transmission signal, obtains the corresponding Fourier spectrum, and obtains the abscissa frequency value corresponding to the maximum peak in the Fourier spectrum. If the abscissa frequency value is located in the preset frequency interval corresponding to the encoded data composed of binary number 0, it is determined that the encoded data corresponding to the wireless data transmission signal is binary number 0; if the abscissa frequency value is located in the preset frequency interval corresponding to the encoded data composed of binary number 1, it is determined that the encoded data corresponding to the wireless data transmission signal is binary number 1; and then the encoded data corresponding to the wireless data transmission signal is obtained, and then enters step D.

[0009] Step D. The Lora receiver decodes the encoded data corresponding to the wireless data transmission signal according to the preset encoding rule in step A, to obtain the corresponding data, that is, to realize real-time obtaining of the target data from the ZigBee terminal by the Lora receiver.

[0010] As a preferred technical solution of the present application: based on the real-time execution of steps A to D, real-time communication from the ZigBee terminal to the Lora receiver is realized. After the Lora receiver receives and detects the preamble sent from the ZigBee terminal, the Lora receiver starts to prepare to receive valid data, so as to obtain complete and valid data from the ZigBee terminal.

[0011] As a preferred technical scheme of the present application: in step A, based on two preset rule special sequences, combining the preset mapping relationship between the coded data and the preset rule special sequences, the ZigBee terminal first applies the DSSS spread spectrum technology, maps the coded data to the corresponding preset rule special sequence, thereby obtaining the corresponding 32-bit Bit sequence, then uses the OQPSK modulation mode to modulate the 32-bit Bit sequence, obtains the wireless data transmission signal of the ZigBee terminal corresponding to the current time and sends it to the Lora receiver.

[0012] As a preferred technical scheme of the present application: based on the obtained coded data of the ZigBee terminal corresponding to the current time consisting of one of binary number 0 or binary number 1, the wireless data transmission signal obtained by the corresponding 32-bit Bit sequence is one of the following two complex exponential signals:

[0013] e j2πft = cos(2πft) + jsin(2πft)

[0014] e -j2πft = cos(2πft) - jsin(2πft)

[0015] Wherein, e j2πft is one of the complex exponential signals, e -j2πft is the other complex exponential signal, f represents the carrier frequency of the wireless data transmission signal, A and φ represent the amplitude and phase of the wireless data transmission signal corresponding to time t respectively, and j is a complex number identifier.

[0016] As a preferred technical scheme of the present application: in step C, the preset frequency interval corresponding to the coded data consisting of binary number 0 and the preset frequency interval corresponding to the coded data consisting of binary number 0 are obtained as follows:

[0017] For each sample coded data consisting of binary number 0 obtained by respectively containing a preset number of effective ZigBee data and according to a preset encoding rule, respectively obtain the sample wireless data transmission signal of each preset rule special sequence by mapping, and then perform Fourier transform to obtain the horizontal coordinate frequency value corresponding to the maximum peak in each sample Fourier spectrum, and the minimum horizontal coordinate frequency value and the maximum horizontal coordinate frequency value are respectively taken as the lower limit value and the upper limit value, thereby forming the preset frequency interval corresponding to the coded data consisting of binary number 0.

[0018] The preset number of each sample coding data respectively containing effective ZigBee data and being formed by binary number 1 according to a preset coding rule is respectively mapped to obtain a sample wireless data transmission signal of each preset rule special sequence, and then a Fourier transform is performed to obtain a horizontal coordinate frequency value corresponding to a maximum wave crest in each sample Fourier spectrum, and the minimum horizontal coordinate frequency value and the maximum horizontal coordinate frequency value are respectively taken as a lower limit value and an upper limit value to form a preset frequency interval corresponding to the coding data formed by the binary number 1.

[0019] As a preferred technical scheme of the present application: in step A, the ZigBee terminal encodes the target data to be sent at the current time by binary conversion to obtain coding data composed of one of binary number 0 or binary number 1.

[0020] As a preferred technical scheme of the present application: the two preset rule special sequences are [1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0] and [1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1].

[0021] Compared with the prior art, the ZigBee to Lora cross-technology communication method based on the physical layer has the following technical effects:

[0022] (1) The ZigBee to Lora cross-technology communication method based on the physical layer is designed, first, the ZigBee terminal encodes the target data to be sent to obtain coding data composed of one of binary number 0 or 1, and maps to form a wireless data transmission signal for sending, then the Lora receiver identifies the received wireless data transmission signal about the effective ZigBee data, further obtains the corresponding coding data through the identification of the Fourier spectrum diagram, finally the Lora receiver decodes and identifies the obtained coding data according to the coding rule of the ZigBee terminal, and obtains the target data from the ZigBee terminal; the design method completes the long-distance communication of the ZigBee terminal to the Lora receiver without the help of an additional gateway, realizes efficient cross-technology communication, saves the hardware cost in the Internet of Things system, and improves the deployment speed of the Internet of Things data acquisition system. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of the ZigBee to Lora cross-technology communication method based on the physical layer designed by the present application;

[0024] Figure 2 is a modulation schematic diagram of the Lora Chirp Spread Spectrum technology CSS;

[0025] Figure 3 is a schematic diagram of the maximum wave peak corresponding to the horizontal coordinate frequency value in the Fourier spectrum diagram obtained by the Lora receiver in the embodiment of the application;

[0026] Figure 4 is a schematic diagram of the communication performance of the design method of the application;

[0027] Figure 5 is a schematic diagram of the outdoor evaluation designed by the application;

[0028] Figure 6 is a schematic diagram of the comparison between the design method of the application and the commercial Lora. DETAILED DESCRIPTION

[0029] The specific embodiments of the application will be further described in detail below with reference to the accompanying drawings of the specification.

[0030] ZigBee is a kind of wireless communication technology based on IEEE802.15.4 protocol, with the advantages of low power consumption, low cost, convenient networking, etc., ZigBee is widely used in the field of Internet of Things, such as many smart furniture products, forest environment monitoring system, etc.

[0031] The physical layer of ZigBee communication technology adopts OQPSK modulation, OQPSK is a kind of digital modulation technology used in wireless communication system, which is a variant of quadrature phase shift keying (QPSK), which reduces the peak-to-average power ratio of the transmitted signal. The working principle of OQPSK is to encode digital data onto a carrier signal by modulating the amplitude and phase of the carrier signal. The modulated signal includes two parts: in-phase (I) component and quadrature (Q) component. In OQPSK, I and Q components are shifted by 90 degrees relative to each other, so that when one component reaches its peak, the other component is at its zero. This method helps to reduce the peak-to-average power ratio of the transmitted signal.

[0032] In the demodulation process, the received signal is divided into its I and Q components, the phase of the Q component is shifted by 90 degrees and compared with the I component. Based on this comparison, a binary value of 0 or 1 is assigned to the Q component. Then the recovered digital data is processed for error correction and decoding. In summary, OQPSK modulation and demodulation involve encoding and recovering digital data by modulating and comparing the phases of the I and Q components of the carrier signal. Digital modulation can be described in the following three steps. First, symbol formation and vector representation--group the information to be transmitted into symbols (i.e. symbols), and then represent each symbol as a vector. Second, baseband modulation--convert the sequence of symbol vectors to be sent into a continuous wave complex signal. Finally, carrier modulation--modulate the baseband continuous wave signal into a bandpass signal.

[0033] The full name of Lora is Long Range Radio, its biggest feature is to realize long distance communication under the same power consumption, even up to 15KM in the suburbs, its modulation mode is CSS modulation scheme based on spread spectrum technology. In Lora modulation, the use of linear frequency pulse can realize low power consumption, long distance and high efficient data transmission. Linear frequency signal is a continuous wave signal whose frequency changes linearly with time. The linear change of frequency leads to the spread spectrum signal occupying a wide bandwidth. In LoRa, a variety of different chirps are used to represent the encoded information in LoRa, and then these chirps are transmitted using frequency shift keying (FSK) modulation, the frequency of the transmitted signal alternates between the frequencies of the up-chirp and the down-chirp.

[0034] Lora adopts linear frequency spread spectrum (CSS) technology, and in LoRa modulation, the use of linear frequency pulse can realize low power consumption, long distance and high efficient data transmission. Linear frequency signal is a continuous wave signal whose frequency changes linearly with time, and different symbols are represented by controlling the starting frequency of sweep. If BW represents the bandwidth of communication, then each symbol transmitted will complete a complete sweep in the frequency range of [-BW / 2, BW / 2], that is, the frequency increases linearly, when the frequency increases to the upper limit BW / 2, it will start from -BW / 2 to continue sweeping, the CSS modulation schematic diagram is shown in Figure 2 According to the CSS modulation specification, we can get the mathematical expressions of t1 and t2:

[0035]

[0036]

[0037] Where k represents the slope of linear sweep, SF represents the spread factor in Lora, and S represents the symbol to be transmitted. For example, when SF = 8, 2 SF different symbols will be generated, and the value range of S at this time is [0-255], and BW in the formula represents the communication bandwidth, and f init is the starting frequency of linear sweep.

[0038] In the demodulation process of LoRa, first multiply the received signal with the down-chirp in time domain, and then perform FFT operation to transform the signal from time domain to frequency domain. The result spectrum obtained by FFT shows the frequency components of the received signal. When demodulating LoRa signal, the FFT spectrum indicates the peak at the 0th position, which is used to demodulate the linear frequency signal corresponding to bit '0'. On the contrary, the peak of bit '1' is located in the middle of the FFT bin. This difference in peak position is due to the initial frequency of the up-chirp used to represent bit '0' and bit '1'.

[0039] Through the above analysis, we know that Lora demodulates the signal by the peak position in the FFT spectrum in the demodulation process, so as long as the waveform of ZigBee can be controlled to make the waveform of ZigBee appear a peak in the FFT spectrum, ZigBee to Lora communication can be realized.

[0040] Therefore, in the design of the present application, the frequency domain signal of ZigBee is analyzed by FFT operation, two special Chip sequences are found and selected, and further experimental analysis proves that Lora can analyze the two special Chip sequences, thereby indicating that Lora can receive cross-technology communication data from ZigBee. Therefore, the DSSS mechanism of ZigBee is modified in the design of the present application, so that ZigBee supports the special Chip sequences mentioned, and finally realizes ZigBee to Lora cross-technology communication at the physical layer.

[0041] That is, the present application designs a ZigBee to Lora cross-technology communication method based on the physical layer. In practical application, as shown in Figure 1 The following steps A to D are performed in real time to realize real-time communication of ZigBee terminal to Lora receiver.

[0042] Step A. First, the ZigBee terminal encodes the target data to be sent at the current time according to a preset encoding rule such as binary conversion, to obtain encoding data composed of one of binary number 0 or binary number 1, and then based on two preset rule special sequences as follows:

[0043] [1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0];[1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1]。

[0044] According to the preset mapping relationship between the encoding data and the preset rule special sequence, the ZigBee terminal first applies the DSSS spread spectrum technology to map the encoding data to the corresponding preset rule special sequence, thereby obtaining a corresponding 32-bit Bit sequence, and uses the OQPSK modulation mode to modulate the 32-bit Bit sequence, that is, maps the encoding data to the corresponding preset rule special sequence to form the wireless data transmission signal of the ZigBee terminal at the current time to the Lora receiver for transmission, and then enters step B.

[0045] The default configuration of ZigBee uses DSSS to spread a four-bit length ZigBee symbol into a predetermined 32-bit chip pseudo noise (PN) sequence. While the PN sequences have robustness against interference and noise, they limit the ability to select arbitrary chips for signal generation. The IEEE 802.15.4G standard specifies that commercial ZigBee wireless chips, such as ATMEL AT86RF233 and ATMEL AT86RF215, can achieve a versatile data rate between 250 kb / s and 2000 kb / s by modifying the spreading factor in the DSSS. This is achieved by configuring the chips to work with various spreading factors, which changes the chip rate and allows more bits to be transmitted per symbol.

[0046] The present application realizes the OQPSK modulation process of ZigBee, and observes the performance of each symbol in ZigBee in the FFT spectrum diagram. Through observation, it is found that the time domain signal of each symbol in ZigBee is not a continuous chord signal, so after FFT operation, many irregular peaks will be obtained on the FFT spectrum diagram, which makes the Lora receiving end unable to demodulate, so as to realize the physical layer cross-technology communication of ZigBee to Lora. Therefore, in order to enable Lora to demodulate the symbols of ZigBee, ZigBee must generate a continuous chord signal, and the present application proposes two special Chip sequences, which are [1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0] and [1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1], the above first sequence is simply referred to as "1100 type Chip sequence" or "1100 type Bit sequence", and the above second sequence is simply referred to as "1001 type Chip sequence" or "1001 type Bit sequence".

[0047] The waveform of various wireless data transmission signals in the air can be expressed by the following mathematical formula:

[0048] Acos(2*π*f*t+φ),

[0049] Where f represents the carrier frequency of the wireless data transmission signal, and A and φ represent the amplitude and phase of the wireless data transmission signal corresponding to time t, respectively, according to the trigonometric function calculation formula:

[0050] cos(α+β)=cos(α)cos(β)–sin(α)sin(β),

[0051] It can be obtained:

[0052] where I = A cos(φ), Q = A sin(φ)

[0053] (1) 1100 type special Chip sequence

[0054] According to the previous analysis, we define the mathematical expression of the I signal as: I = A cos(φ), and the mathematical expression of the Q signal as: Q = A sin(φ). In order to facilitate analysis, we now let A be a unit length of 1, and φ = 2πft. According to Euler's formula:

[0055] e ix = (cos x + isin x)

[0056] By superimposing the I and Q signals together, we get a complex exponential signal:

[0057] e j2πft = cos(2πft) + jsin(2πft)

[0058] (2) 1001 type special Chip sequence

[0059] Unlike the mathematical expression mentioned in (1), the amplitude value of the Q signal of the 1001 type special Chip sequence is the opposite of the amplitude value in (1), so we have I = cos(φ), Q = -sin(φ), φ = 2πft, and using Euler's formula we get a complex exponential signal after IQ superposition:

[0060] e -j2πft = cos(2πft) - jsin(2πft)

[0061] Therefore, in the specific application of step A, based on the obtained ZigBee terminal corresponding to the current time coding data consisting of one of the binary number 0 or binary number 1, the wireless data transmission signal obtained by the corresponding 32-bit Bit sequence is one of the following two complex exponential signals:

[0062] e j2πft = cos(2πft) + jsin(2πft)

[0063] e -j2πft = cos(2πft) - jsin(2πft)

[0064] where e j2πft is one of the complex exponential signals, e -j2πft is the other complex exponential signal, f represents the carrier frequency of the wireless data transmission signal, A and φ represent the amplitude and phase of the wireless data transmission signal corresponding to time t, respectively, and j is the complex identifier.

[0065] Step B. The Lora receiver applies a waveform of the wireless data transmission signal received from the ZigBee terminal to a recognition template for recognizing the ZigBee signal, to recognize whether there is valid ZigBee data in the wireless data transmission signal, and if so, proceed to Step C; otherwise, discard the processing of the wireless data transmission signal. Here, Step B is designed for the recognition of the ZigBee signal, which is crucial because it allows the distinction between the desired signal and any noise or interference that can exist in the received signal.

[0066] Step C. The Lora receiver performs Fourier transform on the wireless data transmission signal to obtain a corresponding Fourier spectrum graph, as shown in Figure 3 Step D. The Lora receiver obtains the horizontal coordinate frequency value corresponding to the maximum peak in the Fourier spectrum graph, and if the horizontal coordinate frequency value is located in a preset frequency interval corresponding to binary number 0, it is determined that the encoded data corresponding to the wireless data transmission signal is binary number 0; if the horizontal coordinate frequency value is located in a preset frequency interval corresponding to binary number 1, it is determined that the encoded data corresponding to the wireless data transmission signal is binary number 1; then the encoded data corresponding to the wireless data transmission signal is obtained, and then Step D is entered.

[0067] In practical applications, in Step C above, the preset frequency interval corresponding to the binary number 0 and the preset frequency interval corresponding to the binary number 0 are obtained as follows:

[0068] For each sample encoded data consisting of binary number 0 obtained by a preset number of valid ZigBee data and a preset encoding rule, a sample wireless data transmission signal of each preset rule special sequence is obtained by mapping, and then Fourier transform is performed to obtain the horizontal coordinate frequency value corresponding to the maximum peak in each sample Fourier spectrum graph, and the minimum horizontal coordinate frequency value and the maximum horizontal coordinate frequency value are taken as the lower limit value and the upper limit value, respectively, to form the preset frequency interval corresponding to the binary number 0.

[0069] For each sample encoded data consisting of binary number 1 obtained by a preset number of valid ZigBee data and a preset encoding rule, a sample wireless data transmission signal of each preset rule special sequence is obtained by mapping, and then Fourier transform is performed to obtain the horizontal coordinate frequency value corresponding to the maximum peak in each sample Fourier spectrum graph, and the minimum horizontal coordinate frequency value and the maximum horizontal coordinate frequency value are taken as the lower limit value and the upper limit value, respectively, to form the preset frequency interval corresponding to the binary number 1.

[0070] In the specific application, according to the selected parameter configuration (setting the bandwidth of Lora to 1024 kHz), after the Lora receiver performs the Fourier transform FFT operation on the wireless data transmission signal, the peak value corresponding to the special ZigBee sequence and the peak value corresponding to the LoRa symbol can overlap together, which means that Lora can receive and decode the transmitted ZigBee signal. The related parameter configuration of the designed Lora is as follows: SF = 8, BW = 1024 kHz, and the LoRa physical layer uses CSS modulation. When SF = 8, each symbol is expanded to 256 (2 SF ) chip sequences. At this time, there are 256 chip sequences, and the initial frequency of each chip sequence is different. This means that the BW is divided into 256 blocks, and the frequency difference between the initial frequencies f init (k) of two chip sequences is f init (k) = (BW x k) / 2 SF , k ∈ [0, 2 SF -1]. As shown in FIG. 8, after the FFT operation, two special ZigBee sequences obtain two peak values, and the horizontal coordinates corresponding to the two peak values are 0.5 MHz and -0.5 MHz, respectively, which overlap with the two symbols of Lora. Therefore, Lora can demodulate the data of ZigBee. Figure 3

[0071] Step D. The Lora receiver decodes the encoded data corresponding to the wireless data transmission signal according to the preset encoding rule in step A to obtain the corresponding data, that is, the Lora receiver obtains the target data from the ZigBee terminal in real time.

[0072] In actual application, based on the real-time execution of steps A to D, real-time communication from the ZigBee terminal to the Lora receiver is realized. When the Lora receiver receives and detects the preamble sent by the ZigBee terminal, the Lora receiver starts to prepare to receive valid data, thereby obtaining complete and valid data from the ZigBee terminal.

[0073] The above-mentioned ZigBee-to-Lora cross-technology communication method based on the physical layer in the actual application realizes long-distance communication, which depends on two key observations. First, the modulation scheme of ZigBee, especially OQPSK, can produce specific signals by manipulating the frame payload, and these signals are composed of continuous single sine waves and can be detected by the receiver. Second, the FFT-based demodulation technology used by the LoRa receiver can also detect and demodulate these specific signals from ZigBee.

[0074] ​In applications, LoRa receivers are known for their exceptional sensitivity and ability to identify very weak LoRa (linear frequency modulated) signals in the presence of strong noise. Therefore, by using the same demodulator that detects LoRa signals, LoRa base stations can also detect and demodulate specific ZigBee signals, even if they are very weak at a long distance. This facilitates the use of ZigRa systems for efficient and reliable long-range communication between ZigBee devices and their base stations, which take full advantage of the strengths of ZigBee and LoRa technologies, providing a reliable and efficient wireless communication solution for long-range Internet of Things applications.

[0075] The above-mentioned designed ZigBee-to-Lora cross-technology communication method based on the physical layer is applied in practice, specifically applied on the USRP-B210 platform using Lora PHY implementation. ZigBee terminals for transmission are implemented on commodity chips (i.e., Atmel AT86RF233 (ZigBee) based on IEEE 802.15.4g). The default transmission power of the ZigBee terminal is set to 0 dBm, the bandwidth of the Lora receiver (Semtech SX1280) is set to 1 or 2 MHz, and the spreading factor SF is set to 8 or 1. The channel frequency is set to 2.4 GHz. In the Lora receiver, we use Lora and USRP-B210 devices to demodulate and decode ZigBee signals.

[0076] The ZigBee-to-Lora cross-technology communication based on the physical layer designed by the present application is defined as ZigRa, Figure 4 The performance of the design scheme of the present application under 1 MHz bandwidth (BW) with different spreading factors (SF) and signal-to-noise ratios (SNR) is shown. Among them, Figure 4 In Fig. (a), it shows that the symbol error rate (SER) in ZigRa applications increases as the Lora signal-to-noise ratio (SNR) decreases. However, compared with other systems, the SER of ZigRa increases much more slowly. Even if the signal power is weaker than the noise (SNR < 0), the SER of ZigRa is still very low. This excellent performance of ZigRa is due to its use of linear frequency demodulation, which helps to concentrate energy and achieve high noise immunity and long-distance transmission, even in the presence of severe signal attenuation during propagation. Figure 4 Fig. (b) shows the throughput of ZigRa with various SF configurations. Lora data packets with smaller SF can provide ZigRa with higher data rates, as smaller SF will result in shorter channel time for each linear frequency signal. In all SNRs, ZigRa has significantly higher throughput because it encodes more bits in each linear frequency signal and experiences lower SER.

[0077] To evaluate the performance of ZigRa in a real outdoor environment, we designed an experiment along a campus road where we varied the distance between the sender and receiver from 100 meters to 500 meters, as shown in Figure 5 The setup of the experiment was carefully chosen with a spreading factor (SF) of 8 and a bandwidth (BW) of 1000 kHz, and a transmission power of 20 dBm. Second, to compare the performance of ZigRa and commercial LoRa, we measured their symbol error rate (SER) and packet reception rate (PRR) and gave the results as shown in Figure 6 As the distance between the sender and receiver increased from 100 meters to 500 meters, the SER of ZigRa increased from 0.18 to 0.66, while the SER of commercial LoRa increased from 0.15 to 0.58. Although ZigRa had a higher SER due to the imperfect emulated signal, it achieved comparable performance to commercial LoRa in both SER and PRR. Therefore, our experiment successfully demonstrated the effectiveness of ZigRa in a real outdoor environment. These findings are particularly applicable to applications that require reliable and efficient long-range wireless communication, such as remote monitoring systems, sensor networks, and smart cities.

[0078] The present application focuses on establishing direct communication from ZigBee to LoRa, supporting long-range cross-technology communication from ZigBee devices to LoRa base stations. The performance of ZigRa was extensively experimented, and the results showed that it can reliably transmit ZigBee communication to LoRa over a distance of more than 500 meters, greatly exceeding the range of native ZigBee communication. Therefore, ZigRa has the potential to solve applications that require long-range communication by expanding the communication range between ZigBee and LoRa networks. At the same time, it enables ZigBee to directly send data to LoRa without the assistance of a gateway, saving hardware costs in Internet of Things systems and improving the deployment speed of Internet of Things data acquisition systems.

[0079] The embodiments of the present application are described in detail above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A ZigBee-to-Lora cross-technology communication method based on physical layer, characterized in that: Real-time execution of the following steps A to D, to achieve ZigBee terminal to Lora receiver direction of real-time communication; Step A. By ZigBee terminal according to the preset encoding rule, for its corresponding current time to be sent target data encoding, obtain the corresponding by one of the binary number 0 or binary number 1 composed of encoding data, and based on two preset rule special sequence, combined with the preset mapping relationship between the encoding data and the preset rule special sequence, the encoding data is mapped to the corresponding preset rule special sequence, to constitute the ZigBee terminal corresponding to the current time of wireless data transmission signal to Lora receiver for sending, and then enter step B; Step B. Lora receiver for the received wireless data transmission signal from ZigBee terminal, the application and wireless data transmission signal waveform is used to identify the detection of ZigBee signal identification template, identify whether there is valid ZigBee data in the wireless data transmission signal, yes, enter step C; otherwise, give up the processing of the wireless data transmission signal; Step C. Lora receiver for the wireless data transmission signal Fourier transform, obtain the corresponding Fourier spectrum, and obtain the horizontal coordinate frequency value corresponding to the maximum peak in the Fourier spectrum, if the horizontal coordinate frequency value is located in the preset frequency interval corresponding to the binary number 0 composed of encoding data, then determine that the encoding data corresponding to the wireless data transmission signal is binary number 0; if the horizontal coordinate frequency value is located in the preset frequency interval corresponding to the binary number 1 composed of encoding data, then determine that the encoding data corresponding to the wireless data transmission signal is binary number 1; further obtain the encoding data corresponding to the wireless data transmission signal, and then enter step D; Step D. Lora receiver according to the preset encoding rule in step A, for the encoding data corresponding to the wireless data transmission signal, obtain the corresponding data, that is, to achieve by Lora receiver real-time target data from ZigBee terminal.

2. The ZigBee to Lora cross-technology communication method based on physical layer according to claim 1, characterized in that: Based on the real-time execution of steps A to D, to achieve ZigBee terminal to Lora receiver direction of real-time communication, when Lora receiver receives and detects the preamble sent from ZigBee terminal, Lora receiver starts to prepare to receive valid data, so as to obtain the complete and effective data from ZigBee terminal.

3. The ZigBee to Lora cross-technology communication method based on physical layer according to claim 1, characterized in that: In step A, based on two preset rule special sequence, combined with the preset mapping relationship between the encoding data and the preset rule special sequence, ZigBee terminal first applies DSSS spread spectrum technology, maps the encoding data to the corresponding preset rule special sequence, so as to obtain the corresponding 32 bit Bit sequence, and then uses OQPSK modulation mode to modulate the 32 bit Bit sequence, obtains the wireless data transmission signal of ZigBee terminal corresponding to the current time and sends it to Lora receiver.

4. The ZigBee to Lora cross-technology communication method based on physical layer according to claim 3, characterized in that: Based on the obtained ZigBee terminal corresponding to the current time of the encoding data consists of one of the binary number 0 or binary number 1, the encoding data corresponding to the 32-bit Bit sequence obtained by the wireless data transmission signal is one of the following two complex exponential signals: ； ； wherein is one of the complex exponential signals, is another of the complex exponential signals, denotes the carrier frequency of the wireless data transmission signal, denotes time, is a complex number identifier.

5. The ZigBee to Lora cross technology communication method based on physical layer according to claim 1, characterized in that: In step C, the preset frequency interval corresponding to the binary number 0 constructed encoding data, and the preset frequency interval corresponding to the binary number 1 constructed encoding data, are obtained as follows: Based on a predetermined number of sample encoding data, and each sample encoding data contains valid ZigBee data, and each sample encoding data is generated according to a predetermined encoding rule, and is composed of binary number 0, each sample encoding data is mapped to obtain a sample wireless data transmission signal of a predetermined rule special sequence, each sample wireless data transmission signal is Fourier transformed again, the horizontal coordinate frequency value corresponding to the maximum peak in each sample Fourier spectrum is obtained, and the minimum horizontal coordinate frequency value and the maximum horizontal coordinate frequency value are used as the lower limit value and the upper limit value, respectively, to form the preset frequency interval corresponding to the binary number 0 constructed encoding data; Based on a predetermined number of sample encoding data, and each sample encoding data contains valid ZigBee data, and each sample encoding data is generated according to a predetermined encoding rule, and is composed of binary number 1, each sample encoding data is mapped to obtain a sample wireless data transmission signal of each predetermined rule special sequence, each sample wireless data transmission signal is Fourier transformed again, the horizontal coordinate frequency value corresponding to the maximum peak in each sample Fourier spectrum is obtained, and the minimum horizontal coordinate frequency value and the maximum horizontal coordinate frequency value are used as the lower limit value and the upper limit value, respectively, to form the preset frequency interval corresponding to the binary number 1 constructed encoding data.

6. The ZigBee to Lora cross-technology communication method based on physical layer according to claim 1 or 5, characterized in that: In step A, the ZigBee terminal encodes the target data corresponding to the current time according to the binary conversion method, and obtains the corresponding encoding data composed of one of the binary number 0 or binary number 1.

7. The ZigBee to Lora cross-technology communication method based on physical layer according to claim 1 or 5, characterized in that: The two predetermined rule special sequences are [1,1,0,0, 1,1,0,0, 1,1,0,0, 1,1,0,0, 1,1,0,0, 1,1,0,0, 1,1,0,0, 1,1,0,0] and [1,0,0,1, 1,0,0,1, 1,0,0,1, 1,0,0,1, 1,0,0,1, 1,0,0,1, 1,0,0,1, 1,0,0,1].

Images