A LoRa device positioning apparatus

Abstract

The application relates to a LoRa device positioning device which comprises a LoRa data transceiving unit, a LoRa antenna array receiving positioning unit, a central processing control unit and a bidirectional data interface unit. The central processing control unit is connected with the LoRa data transceiving unit, the LoRa antenna array receiving positioning unit and the bidirectional data interface unit respectively. The signal emitted by the LoRa device enters the LoRa data transceiving unit to obtain a LoRa data packet and signal quality, and enters the LoRa antenna array receiving positioning unit to obtain positioning data. The central processing control unit reads the LoRa data packet, the signal quality and the positioning data, judges whether the positioning data is valid, and if yes, the bidirectional data interface unit forwards the positioning data. Compared with the prior art, time synchronization and a fingerprint library are not needed, and high-precision positioning is realized.

Description

Technical Field

[0001] This invention belongs to the field of wireless positioning technology and relates to a LoRa device positioning device. Background Technology

[0002] With the rapid rise of IoT technology, a large number of device positioning needs have emerged. Traditional wireless technologies such as Wi-Fi, Bluetooth, and ZigBee can compensate for the relatively large positioning errors of GPS indoors to some extent, but they cannot replace GPS in outdoor applications due to limitations in communication distance. In outdoor positioning solutions, LPWAN technologies are commonly used to achieve lower power consumption, such as NB-IoT technology in the licensed SubG frequency band and SIGFox and LoRa in the unlicensed SubG frequency band. Among them, LoRa has been widely used due to its strong anti-interference ability, simple network topology, and low cost.

[0003] In existing technologies, the commonly used positioning methods in the LoRa field are mainly divided into two types: RSSI signal strength-based positioning and time synchronization-based positioning. Typical solutions include RSSI fingerprint positioning, TDoA time difference positioning, or a combination of both. RSSI positioning calculates location based on the relationship between signal strength and distance. However, since the relationship between signal strength and distance is non-linear, and signal strength is unstable due to many factors, TDoA technology uses time difference for positioning. Only with more accurate time synchronization can the time difference collected during operation be more accurate. However, in practice, time synchronization is difficult to control, and the positioning accuracy of both methods is generally not ideal. Therefore, positioning solutions combining LoRa with other wireless technologies have also emerged, such as combined positioning solutions with Bluetooth, GPS, or UWB, but the cost has increased significantly accordingly. Summary of the Invention

[0004] The purpose of this invention is to provide a LoRa device positioning device to overcome the problems of insufficient positioning accuracy and high cost in the prior art.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A LoRa device positioning apparatus includes a LoRa data transceiver unit, a LoRa antenna array receiving and positioning unit, a central processing and control unit, and a bidirectional data interface unit.

[0007] The central processing and control unit is connected to the LoRa data transceiver unit, the LoRa antenna array receiving and positioning unit, and the bidirectional data interface unit, respectively.

[0008] The LoRa antenna array receiving and positioning unit includes an antenna array, a matching circuit, a radio frequency front end, and an integrated chip connected in sequence.

[0009] Furthermore, the LoRa data transceiver unit includes an antenna, a matching circuit, an RF switch, an RF front-end, and a LoRa transceiver connected in sequence.

[0010] Furthermore, the antenna is a LoRa device-specific unlicensed radio band antenna.

[0011] Furthermore, the integrated chip is an FPGA chip.

[0012] Furthermore, the central processing control unit includes a microprocessor and a microcontroller.

[0013] Furthermore, the microprocessor is an ARM Cortex-A series microprocessor.

[0014] Furthermore, the microcontroller is an ARM Cortex-M series microcontroller.

[0015] Furthermore, the bidirectional data interface unit includes a wired data interface and a wireless data interface.

[0016] Furthermore, the wired data interface includes a standard SPI bus, a UART asynchronous transmission serial port, a standard IIC bus, and general-purpose GPIO.

[0017] Furthermore, the wired data interface and the wireless data interface support both wired and wireless modes. The wired modes include RS458, RS232, CAN, and Ethernet, while the wireless modes include WIFI, 4G, and Bluetooth.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. This invention includes a LoRa data transceiver unit, a LoRa antenna array receiving and positioning unit, a central processing control unit, and a bidirectional data interface unit. The LoRa data transceiver unit is used to acquire LoRa data packets and signal quality. The LoRa antenna array receiving and positioning unit is used to acquire positioning data. The central processing control unit is used to read the LoRa data packets, signal quality, and positioning data, and determine whether the positioning data is valid. If so, the bidirectional data interface unit receives and forwards the positioning result, thereby realizing the positioning of the LoRa device. It does not require time synchronization or the establishment of a fingerprint database, achieving high-precision positioning while also having the advantage of low cost.

[0020] 2. The LoRa antenna array receiving and positioning unit in this invention includes an antenna array, a matching circuit, a radio frequency front-end, and an integrated chip connected in sequence. The antenna array is used to receive signals emitted by LoRa devices, the matching circuit is used for filtering, the radio frequency front-end is used for tuning, mixing, and analog-to-digital conversion, and the integrated chip is used for parallel processing to calculate angle values. Then, based on multiple angles, the relative coordinates of the device that emitted the LoRa signal are determined, thus realizing AoA position calculation without affecting the normal transmission of LoRa data. Attached Figure Description

[0021] Figure 1 This is a structural diagram of the LoRa-based AoA positioning device of the present invention;

[0022] Figure 2 This is a schematic diagram of LoRa AoA measurement according to the present invention;

[0023] Figure 3 This is a schematic diagram of the LoRa preamble symbol frequency domain of the present invention;

[0024] Figure 4 This is a schematic diagram of the LoRa symbol frequency domain under the multipath effect of the present invention;

[0025] Figure 5 This is a flowchart illustrating the LoRa device location determination process of the present invention.

[0026] Figure 6 This is a hardware block diagram of the LoRa AoA positioning device of the present invention;

[0027] Figure 7 This is a hardware block diagram of the LoRa+MCU device of the present invention;

[0028] Figure 8 This is a hardware block diagram of the LoRa SoC device of the present invention;

[0029] Explanation of markings in the diagram:

[0030] 1—LoRa data transceiver unit, 11—antenna, 12—RF switch, 13—LoRa transceiver, 2—LoRa antenna array receiving and positioning unit, 21—antenna array, 22—integrated chip, 3—central processing and control unit, 4—bidirectional data interface unit, 5—matching circuit, 6—RF front end. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0032] Example:

[0033] This embodiment proposes a LoRa device positioning device, see [link / reference] Figure 1 This is a structural diagram of a LoRa-based positioning device, including a LoRa data transceiver unit 1, a LoRa antenna array receiving and positioning unit 2, a central processing control unit 3, and a bidirectional data interface unit 4. The central processing control unit 3 is connected to the LoRa data transceiver unit 1, the LoRa antenna array receiving and positioning unit 2, and the bidirectional data interface unit 4, respectively. It mainly realizes the function of locating LoRa devices and forwarding message data and location data, and solves the problem of acquiring LoRa I / Q data.

[0034] Specifically, the LoRa data transceiver unit 1 includes an antenna 11, a matching circuit 5, an RF switch 12, an RF front-end 6, and a LoRa transceiver 13 connected in sequence, mainly realizing bidirectional communication with LoRa devices and the acquisition of LoRa data packet signal quality.

[0035] Specifically, the receiving operation is as follows: the signal emitted by the LoRa device is received by the frequency band matched antenna, then filtered by the matching circuit 5, and then enters the radio frequency front-end 6 for tuning, mixing and analog-to-digital conversion through the switch to enter the receiving link. It is then demodulated by the receiver in the LoRa transceiver 13, and the obtained LoRa data packets and signal quality are transmitted to the central processing control unit 3.

[0036] The specific transmission operation is as follows: the central processing control unit 3 transmits the data packet to be transmitted to the LoRa transceiver 13, which then performs LoRa modulation, and the RF front-end 6 performs RF modulation. The data is then transmitted through the switch and matching circuit 5 that enters the transmission link, and finally radiated into the air by the antenna 11. The parameters of the RF switch 12 and the LoRa transceiver 13 are issued by the central processing control unit 3.

[0037] Specifically, the LoRa antenna array receiving and positioning unit 2 includes an antenna array 21, a matching circuit 5, an RF front end 6, and an integrated chip 22 connected in sequence. It mainly realizes the functions of AoA (angle of arrival) angle calculation and position coordinate calculation for the received LoRa signal.

[0038] The specific operating procedure is as follows: The signal emitted by the LoRa device is received by the frequency-matched antenna array 21, filtered by the matching circuit 5, and then enters the RF front-end 6 through the switch to switch into the receiving link for tuning, mixing, and analog-to-digital conversion. The resulting multiple sets of I / Q signal data are processed in parallel by the integrated chip 22. The angle value is calculated based on the phase difference of each set of I / Q data, and the relative coordinates of the device emitting the LoRa signal are determined based on multiple angles. These multiple sets of coordinates are then transmitted to the central processing control unit 3. The LoRa demodulation parameters and AoA positioning algorithm parameters in the integrated chip 22 are issued by the central processing control unit 3. In this embodiment, the integrated chip uses an FPGA.

[0039] Specifically, the central processing and control unit 3 includes a microprocessor and a microcontroller, which mainly realize the functions of fusion and determination of LoRa device location information, coordination and control of the operation of LoRa data transceiver unit 1 and LoRa antenna array receiving and positioning unit 2, LoRa communication protocol processing and data forwarding with the positioning target device.

[0040] The specific operating method is as follows: Based on the quality of the received LoRa data packet signal and multiple sets of location data, the system classifies and judges the data to determine whether the current location is valid. According to functional requirements, the data packet and location data are forwarded through the bidirectional data interface unit 4. In this embodiment, the microprocessor is a 64-bit 4× -A76+4× - A55SoC RK3588 microprocessor, with a 32-bit microcontroller. -M4F MCU GD32F470 series microcontrollers.

[0041] Specifically, the bidirectional data interface unit 4 includes a wired data interface and a wireless data interface. It primarily implements the system's bidirectional data interaction function. It can receive external data transmission and reception control requests, perform bidirectional data transmission through the LoRa data transceiver unit 1, and simultaneously package and forward the processed location information as needed. The data interface supports wired methods such as RS458, RS232, CAN, and Ethernet, as well as wireless methods such as WIFI and 4G.

[0042] In a specific application example, the LoRa device location determination process of the present invention includes the following steps, see... Figure 5 :

[0043] (1) Connect the LoRa positioning device to a power source;

[0044] (2) The central processing and control unit 3 in the LoRa positioning device configures the LoRa data transceiver unit 1 and the LoRa antenna array receiving and positioning unit 2, specifically:

[0045] The microcontroller configures the LoRa transceiver parameters and configures the RF front-end parameters through the LoRa transceiver. The microcontroller then switches the RF switch to receive mode.

[0046] The microcontroller configures the positioning algorithm parameters in the FPGA and configures the RF front-end parameters through the FPGA.

[0047] (3) The LoRa device sends normal communication data packets;

[0048] (4) LoRa data transceiver unit 1 receives data packets and analyzes the signal quality indicators RSSI and SNR, specifically:

[0049] The LoRa signal is amplified, mixed, and converted from analog to digital by the RF front end, and then demodulated by the transceiver to obtain valid data. The microcontroller reads the LoRa data packets and the corresponding RSSI and SNR of the received signal through the bus interface.

[0050] (5) The LoRa antenna array receiving and positioning unit 2 calculates multiple sets of position information based on the variable preamble part of the data packet. Specifically, multiple LoRa signals are amplified, mixed, and converted from analog to digital by the radio frequency front end to obtain I / Q data groups. The AoA positioning algorithm built into the FPGA calculates the collected I / Q data to obtain position data. The microcontroller reads the multiple sets of position data obtained by AoA positioning through the bus interface.

[0051] (6) The central processing control unit 3 reads LoRa data packets, signal quality data, and multiple sets of location data from the LoRa data transceiver unit 1 and the LoRa antenna array receiving and positioning unit 2, and classifies the positioning signals and evaluates the reliability of the positioning results.

[0052] (7) If the location data is valid, it is forwarded through the bidirectional data interface unit 4 in the LoRa positioning device; otherwise, the positioning process ends.

[0053] See Figure 2 When a LoRa-located target emits a radio frequency signal, and the distance to the LoRa receiving antenna array 21 is much greater than the current signal wavelength, the wavefront can be approximately considered as a plane relative to the antenna. Therefore, there is a phase difference when the wavefront reaches a pair of antennas. The arrival angle of the wavefront can be calculated by the following formula:

[0054]

[0055] In the formula, Let λ be the phase difference between the same wavefront and the pair of antennas, d be the wavelength, and d be the distance between the pair of antennas. Furthermore, to ensure that the wavefronts reaching the pair of antennas are the same wavefront, the following condition must be met:

[0056]

[0057] According to the axiom, the coordinates of a LoRa device in the plane can be determined by calculating the two angles of arrival from at least two pairs of antennas. Redundancy calculations can be performed by increasing the number of antenna pairs or orthogonally arranging them, thereby improving positioning accuracy.

[0058] Based on the structural characteristics of LoRa physical layer data packets, which consist of a preamble, a configurable physical layer header, a valid data payload, and a configurable CRC hardware checksum, the preamble and valid data payload are mandatory. According to the principle of LoRa spread spectrum modulation, a complete preamble consists of variable preamble symbols, a frame synchronization word, and a preamble end identifier. The frame synchronization word is mainly used by the receiver to determine whether it is a LoRaWAN data packet. The preamble end identifier, as the only DOWN-CHIRP process in LoRa modulation, has a typical indicative function, and the variable preamble symbol portion is entirely a UP-CHIRP process without data modulation. This method is based on this characteristic, capturing the phase difference of the variable preamble symbol portion to calculate the AoA (Aspect-of-Aspect Ratio).

[0059] See Figure 3 This is a schematic diagram of the LoRa preamble symbol frequency domain. The diagram shows the frequency domain waveforms of the same wavefront on a pair of antennas, namely antenna A and antenna B. c Here, BW represents the center frequency of the LoRa signal, BW is the bilateral bandwidth of the LoRa modulation, and t0 is the start time for truncating the complete preamble symbol. Specifically, after the antenna processes the received LoRa data packet signal through the RF section, it obtains continuously sampled I / Q data. The I / Q data undergoes frequency offset compensation and correction filtering and is then transferred to the time domain. Next, it is truncated according to the DOWN-CHIRP characteristics. Then, the phase difference of each valid symbol in the variable preamble symbol is calculated, and the AoA angle value is further calculated. Finally, multiple sets of coordinate data consistent with the number of symbols are calculated. Among them, due to the multipath effect, spurious interference signals appear. This method filters them during I / Q data correction by setting a signal strength threshold.

[0060] Under the influence of radio multipath effects, see Figure 4In this scenario, the antenna will inevitably receive multiple non-direct LoRa signals. Taking two non-direct signals, A and B, as examples in the diagram, signal A shows a significant frequency shift, while signal B, in addition to frequency shift, also exhibits non-standardized symbols. In this case, due to LoRa's strong anti-interference capability, the non-direct signals can still be demodulated, but the angle deviation calculated by AoA increases dramatically. Therefore, a method is proposed to classify and judge the multiple sets of demodulated location data by introducing LoRa signal RSSI and SNR indices. Specifically, a classification evaluation model for positioning results is established based on the statistical characteristics of multiple sets of location data and the limiting SNR and RSSI corresponding to the spreading factor SF in different LoRa modulations. Specifically, a classification model is established using the standard deviation, pairwise covariance, SNR, and RSSI of multiple sets of location data as features to classify the location data calculated from direct and non-direct signals, and to evaluate the positioning accuracy. Positioning results that fail the evaluation are discarded, and the location data is then fused to give the final location coordinates. The above model is established using machine learning or statistical methods.

[0061] More specifically, in this embodiment, the positioning device mainly consists of the following parts, see... Figure 6 :

[0062] System power supply: Provides power to all parts of the system to ensure normal operation.

[0063] The ARM SoC processor minimum system is responsible for system location data processing and data transmission with external devices or platforms: processor SoC chip, LPDDR4 memory (capacity greater than 4G), external data storage eMMC or SD card or M.2 PCIe interface SSD solid-state drive (capacity greater than 64G).

[0064] Network interfaces: Mobile 4G / 5G network (to realize end-to-platform data transmission link), WIFI or Bluetooth wireless configuration interface (WIFI can also be used for local area network data transmission), Gigabit Ethernet LAN port (to realize data transmission).

[0065] Hardware interfaces: standard SPI bus, UART asynchronous transmission serial port, standard IIC bus, and general-purpose GPIO, enabling LoRa-related data transmission within the device.

[0066] LoRa data transceiver unit 1: Transmits the received LoRa data and signal quality information to the ARM processor, and forwards the data packets sent by the ARM processor, realizing LoRa data transmission and compatible with two design modes:

[0067] The LoRa SoC communicates with the ARM SoC via UART and performs half-duplex LoRa data packet transmission and reception via RF switch 12.

[0068] The LoRa modem communicates with the ARM SoC via SPI, controls the LoRa RF front-end 6 via SPI, and performs half-duplex LoRa data packet transmission and reception via RF switch 12.

[0069] Integrated chip I / Q computing unit: High-speed data transmission and reception are achieved through the integrated chip 22 and the custom parallel data interface of ARM GPIO. The integrated chip 22 enables communication between multiple sets of parallel SPI cores and 6 sets of RF front-ends. Internally, the multiple sets of I / Q data are demodulated by coordinates and then sent to the ARM processor.

[0070] Antenna interfaces: at least including GPS x 1, 4G / 5G x 1, 2.4G x 1, 433-510MHz x (transceiver + array). Specifically, this invention needs to include all available free frequency bands for LoRa, of which 433-510MHz is China's SUBG band.

[0071] LoRa device tagging solution for location:

[0072] The tag sends out standard LoRa data packets for the positioning device to detect. Figure 7 and Figure 8 The block diagrams are designed for two common LoRa devices. The positioning device has no special requirements for LoRa devices.

[0073] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A LoRa device positioning device, characterized in that, It includes a LoRa data transceiver unit (1), a LoRa antenna array receiving and positioning unit (2), a central processing and control unit (3), and a bidirectional data interface unit (4). The central processing control unit (3) is connected to the LoRa data transceiver unit (1), the LoRa antenna array receiving and positioning unit (2), and the bidirectional data interface unit (4), respectively. The LoRa antenna array receiving and positioning unit (2) includes an antenna array (21), a matching circuit (5), a radio frequency front end (6), and an integrated chip (22) connected in sequence. Normal communication data packets sent by LoRa devices are received by the frequency band matched antenna array (21), filtered by the matching circuit (5), and then entered into the radio frequency front end (6) for tuning, mixing and analog-to-digital conversion via the switch to enter the receiving link. The resulting multiple sets of I / Q signal data are processed in parallel by the integrated chip (22). The angle value is calculated based on the phase difference of each set of I / Q data, and the relative coordinates of the device that sends the LoRa signal are determined based on multiple angles. The multiple sets of coordinates are then transmitted to the central processing control unit (3). The LoRa data transceiver unit (1) includes an antenna (11), a matching circuit (5), an RF switch (12), an RF front end (6), and a LoRa transceiver (13) connected in sequence.

2. The LoRa device positioning device according to claim 1, characterized in that, The antenna (11) is a LoRa device-specific unlicensed radio band antenna.

3. The LoRa device positioning device according to claim 1, characterized in that, The integrated chip (22) is an FPGA chip.

4. The LoRa device positioning device according to claim 1, characterized in that, The central processing control unit (3) includes a microprocessor and a microcontroller.

5. A LoRa device positioning device according to claim 4, characterized in that, The microprocessor mentioned is an ARMCORTEX-A series microprocessor.

6. A LoRa device positioning device according to claim 4, characterized in that, The microcontroller in question is an ARMCORTEX-M series microcontroller.

7. A LoRa device positioning device according to claim 1, characterized in that, The bidirectional data interface unit (4) includes a wired data interface and a wireless data interface.

8. A LoRa device positioning device according to claim 7, characterized in that, The wired data interfaces include a standard SPI bus, a UART asynchronous serial port, a standard IIC bus, and general-purpose GPIO.

9. A LoRa device positioning device according to claim 8, characterized in that, The wired and wireless data interfaces support both wired and wireless modes. Wired modes include RS458, RS232, CAN, and Ethernet, while wireless modes include WIFI, 4G, and Bluetooth.

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