A method and system for reliable real-time data packet reception in user-defined overlapping loRa channels

Abstract

This invention provides a reliable real-time data packet reception method and system in a user-defined overlapping LoRa channel. The method includes the following steps: performing preamble detection on the original I / Q sampled signal using a sliding demodulation window to determine the distribution of the preamble frequency domain energy peaks; determining the target data packet based on the distribution of the preamble frequency domain energy peaks; determining the candidate duration of the signal cancellation window based on multiple preamble chirped signals of the target data packet and a pre-established mapping relationship; determining the actual signal cancellation position set based on the candidate duration, the starting position of the sliding demodulation window, and the maximum number of signal cancellations that the gateway can execute; canceling the time domain signal corresponding to the time period from the received signal within the current sliding demodulation window to obtain the residual frequency domain energy peak distribution under the cancellation rounds; calculating the target energy peak corresponding to the current chirp based on the residual frequency domain energy peak distribution; and using the frequency point corresponding to the target energy peak as the demodulation result of the current chirp.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a reliable real-time data packet reception method and system in a user-defined overlapping LoRa channel. Background Technology

[0002] LoRaWAN, a low-power wide-area network technology, enables long-distance data transmission under low power consumption and has been used in applications such as smart cities, environmental monitoring, asset tracking, and the Industrial Internet of Things (IIoT). In practical deployments, to adapt to the spectrum management and network capacity requirements of different regions, users or network operators can typically configure the center frequency of logical channels with a certain combination of bandwidth and spreading factors. Since different LoRa terminal devices or different LoRa networks may independently select their center frequencies, multiple logical channels operating in adjacent areas can easily form user-defined overlapping LoRa channels with partially overlapping frequency bands.

[0003] In overlapping channel scenarios, when a LoRa gateway receives data packets on the target channel, it may simultaneously receive interfering data packets from other overlapping channels. These interfering data packets may cause the gateway to incorrectly lock onto the interfering packet during the preamble detection phase, or they may cause the interfering chirp portion to fall into the sliding demodulation window of the target data packet after it has been correctly locked onto. Since the LoRa demodulation process typically relies on determining the frequency point of the despread energy peak, when the energy peak of the interfering chirp is higher than that of the target chirp, the standard demodulator may incorrectly identify the interfering peak as the target energy peak, leading to symbol decision errors.

[0004] Existing methods for handling colliding packets achieve multi-packet reception within a single channel through serial interference cancellation, energy peak ratio tracking, or common energy peak search. These methods typically assume that the start and end times of each colliding chirp are predictable, or that chirp boundaries can be inferred from the energy peak relationships between adjacent sliding demodulation windows. However, in user-defined overlapping LoRa channels, the center frequency, arrival time, and modulation symbols of interfering packets are all random. Interfering chirs may only partially fall within the target sliding demodulation window, and their start and end times are difficult to determine directly from common energy peaks. Therefore, existing serial cancellation or common peak search methods are not reliably applicable to overlapping channel interference.

[0005] Another class of methods employs centralized scheduling, carrier sensing, or backoff mechanisms to reduce the probability of collisions. The goal of these methods is to avoid collisions as much as possible, rather than recovering the target data packet after a collision occurs. In LoRa networks coexisting independently operated by multiple users, a single gateway struggles to coordinate frequency or time resources across the network. Terminal-side carrier sensing can also reduce channel utilization due to hidden or exposed terminals and dense deployment of backoff mechanisms. Therefore, existing collision avoidance methods cannot reliably and in real-time provide packet reception capabilities in user-defined overlapping LoRa channel environments. Summary of the Invention

[0006] In view of this, embodiments of the present invention provide a reliable real-time data packet reception method in a user-defined overlapping LoRa channel to eliminate or improve one or more defects existing in the prior art.

[0007] One aspect of the present invention provides a method for reliable real-time data packet reception in a user-defined overlapping LoRa channel, the method being applied to a LoRa gateway, the method comprising the following steps: The raw I / Q sampled signal received by the radio frequency front end is acquired, and a preamble detection is performed on the raw I / Q sampled signal using a sliding demodulation window. The distribution of the preamble frequency domain energy peak is determined based on the result of the preamble detection. The target data packet is determined based on the distribution of the preamble frequency domain energy peak, the average signal-to-noise ratio is determined based on the multiple preamble chirped signals of the target data packet, and the candidate duration of the signal cancellation window is determined according to the average signal-to-noise ratio and the pre-established signal-to-noise ratio-minimum distance threshold mapping relationship. The actual signal cancellation location set is determined based on the candidate duration, the starting position of the sliding demodulation window, and the maximum number of signal cancellations that the gateway can perform. For each signal cancellation position in the actual signal cancellation position set, the time domain signal of the corresponding time period is eliminated from the received signal in the current sliding demodulation window, and despreading and fast Fourier transform are performed on the residual signal after cancellation to obtain the residual frequency domain energy peak distribution under the corresponding cancellation round. The amplitude reduction ratio of the energy peak at each frequency point is calculated based on the residual frequency domain energy peak distribution, and the target energy peak corresponding to the current Chirp is determined according to the deviation between the amplitude reduction ratio and the expected reduction ratio of the target Chirp. The frequency point corresponding to the target energy peak is used as the demodulation result of the current Chirp, and the target energy peak determination process is repeated until the demodulation of the target data packet payload is completed.

[0008] Using the above scheme, the LoRa gateway first locks the target data packet by jointly verifying the preamble and the center frequency offset, avoiding incorrect entry into the subsequent demodulation process when the interfering data packet arrives first or has higher energy. After the target data packet is locked, a limited number of time-domain signal cancellation positions are adaptively selected according to the current channel noise state, so that each cancellation can form a distinguishable amplitude reduction response to the target chirp and partially overlapping interfering chirps. Finally, the target energy peak is determined through multiple rounds of deviation sorting and voting, thereby completing real-time demodulation without the need to accurately estimate the start and end boundaries of the interfering chirp.

[0009] In some embodiments of the present invention, in the step of determining the distribution of the preamble frequency domain energy peak based on the result of the preamble detection, after detecting a preset number of consecutive chirped signals, despreading and fast Fourier transform are performed on the chirped and lower chirped signals in the preamble, respectively, to obtain the distribution of the preamble frequency domain energy peak.

[0010] In some embodiments of the present invention, in the step of determining the target data packet based on the distribution of the preamble frequency domain energy peaks, it is checked whether there is an energy peak in the preset center frequency offset band after the lower chirp signal in the preamble is despread; if there is no energy peak, the currently determined data packet is determined to be an interference data packet and discarded; if there is an energy peak, the amplitude ratio of different energy peaks in the preset center frequency offset band is compared, and the data packet corresponding to the energy peak whose amplitude ratio falls within the preset amplitude ratio range is identified as the target data packet.

[0011] In some embodiments of the present invention, in the step of determining the average signal-to-noise ratio based on multiple preamble chirped signals of the target data packet, the average signal-to-noise ratio is calculated using the following formula: in, Indicates the average signal-to-noise ratio; Indicates the number of preamble chirps in the target data packet; This represents the signal-to-noise ratio corresponding to the chirped signal on the nth preamble.

[0012] In some embodiments of the present invention, in the step of determining the candidate duration of the signal cancellation window based on the average signal-to-noise ratio and the pre-established signal-to-noise ratio-minimum distance threshold mapping relationship, the candidate duration is calculated using the following formula: in, This represents the minimum distance threshold corresponding to the current average signal-to-noise ratio; This represents the signal-to-noise ratio-minimum distance threshold mapping relationship established in advance through actual measurements; Indicates the candidate duration of the signal cancellation window; This represents the total duration of a sliding demodulation window.

[0013] In some embodiments of the present invention, in the step of determining the actual signal cancellation position set based on the candidate duration, the starting position of the sliding demodulation window and the maximum number of signal cancellations that the gateway can perform, the signal cancellation window is moved with a preset sampling step size starting from the starting position of the sliding demodulation window to generate a candidate position pair set, wherein each candidate position pair in the candidate position pair set includes the start time and end time of signal cancellation. The LoRa gateway numbers the candidate position pairs in the candidate position pair set according to the order in which each candidate position pair appears in the sliding demodulation window. When the total number of candidate position pairs exceeds the maximum number of executable signal eliminations, all candidate position pairs are divided into multiple candidate segments corresponding to the maximum number of executable signal eliminations according to their numbering order. The LoRa gateway selects one candidate location pair from each candidate segment as the actual signal cancellation location pair, and forms an actual signal cancellation location set from the selected multiple actual signal cancellation location pairs.

[0014] In some embodiments of the present invention, the candidate position pair set is generated using the following formula: Where Ω represents the set of candidate position pairs; and These represent the start and end times of the m-th candidate signal elimination position pair, respectively. Indicates the start time of the sliding demodulation window. This represents the total duration of a sliding demodulation window.

[0015] In some embodiments of the present invention, in the step of calculating the amplitude reduction ratio of the energy peak at each frequency point based on the residual frequency domain energy peak distribution, the amplitude reduction ratio is determined using the following formula: in, Indicates the expected reduction rate of the target Chirp; This represents the duration of the elimination window corresponding to the j-th round of signal elimination; This represents the actual amplitude reduction rate of the energy peak value at the k-th frequency point after the j-th round of elimination; This represents the peak value of the residual frequency domain energy at the k-th frequency point after the j-th round of elimination; This represents the peak energy amplitude at the k-th frequency point before elimination; This represents the deviation value corresponding to the k-th frequency point in the j-th round of elimination.

[0016] In some embodiments of the present invention, in the step of determining the target energy peak corresponding to the current Chirp based on the deviation between the amplitude reduction ratio and the expected reduction ratio of the target Chirp, the deviation values ​​of each frequency point in each elimination round are sorted, and the number of times each frequency point becomes the minimum deviation frequency point is counted; if any frequency point corresponds to the minimum deviation value in more than half of the elimination rounds, the energy peak of that frequency point is determined as the target energy peak; otherwise, auxiliary correction is performed based on the average amplitude of the energy peak in the preamble of the target data packet, and the energy peak of the frequency point whose amplitude is closest to the average amplitude of the energy peak is determined as the target energy peak.

[0017] A second aspect of the present invention also provides a reliable real-time data packet reception system in a user-defined overlapping LoRa channel. The system includes a computer device, the computer device including a processor and a memory, the memory storing computer instructions, and the processor executing the computer instructions stored in the memory. When the computer instructions are executed by the processor, the system implements the steps of the method described above.

[0018] A third aspect of the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the aforementioned method for predicting multimodal anomalies in a logistics supply chain based on a hybrid expert model.

[0019] Additional advantages, objects, and features of the invention will be set forth in part in the description which follows, and will also become apparent in part to those skilled in the art upon studying the text, or may be learned by practice of the invention. The objects and other advantages of the invention will become apparent from the description and the accompanying drawings.

[0020] Those skilled in the art will understand that the objectives and advantages achievable with the present invention are not limited to those specifically described above, and that the above and other objectives achievable with the present invention will become clearer from the following detailed description. Attached Figure Description

[0021] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, are not intended to limit the scope of the invention.

[0022] Figure 1 This is a schematic diagram illustrating one implementation of the present solution; Figure 2 This is a schematic diagram of the overall processing flow of this solution; Figure 3 A schematic diagram of overlapping channel interference in a LoRa network; Figure 4 This is a schematic diagram illustrating decoding errors caused by overlapping channel interference. Figure 5 This is a schematic diagram of the overall framework of this solution; Figure 6 This diagram illustrates the CFO calculation method used in this solution and existing technologies for target data packet identification. Figure 7 This is a schematic diagram illustrating the signal-to-noise ratio (SNR) versus minimum distance threshold mapping relationship. Figure 8 A schematic diagram illustrating the principle of time-domain erasure; Figure 9 This is a schematic diagram of the noise perception adaptive signal cancellation location determination process for this scheme. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. Here, the illustrative embodiments and descriptions of this invention are used to explain the invention, but are not intended to limit the invention.

[0024] It should also be noted that, in order to avoid obscuring the invention with unnecessary details, only the structures and / or processing steps closely related to the solution according to the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0025] When multiple LoRa terminal devices or independent LoRa networks operate simultaneously in adjacent areas, they may each select different center frequencies, but their occupied frequency bands partially overlap due to their large bandwidth. In this overlapping channel scenario, when a gateway attempts to receive data packets on its target channel, it often simultaneously receives interfering data packets from other overlapping channels. These interfering data packets may not only arrive first and be incorrectly locked to the preamble by the gateway, causing the target data packet to be directly discarded; more commonly, even after correctly locking onto the target data packet, some chirps in the interfering data packets may still fall within the demodulation window of the target data packet, colliding with the target chirp. Since LoRa demodulation relies on determining the frequency of the despread energy peak, when the power of the interfering chirp is higher than the target chirp, the standard demodulator will incorrectly select the interfering energy peak, resulting in demodulation errors. This interference caused by user-defined overlapping channels is called overlapping channel interference. Unlike traditional single-channel packet collisions, the center frequency, start time, and end time of the interfering chirp in overlapping channel interference are highly random and unpredictable, posing a severe challenge to reliable data packet reception.

[0026] Introduction to existing technologies Existing technology 1 In existing technologies, a typical approach is to achieve concurrent data packet demodulation within a single channel through serial interference cancellation. For example, the mLoRa method, after detecting a collision, first reconstructs the time-domain waveform of the complete chirp based on the energy peak, and then separates multiple data packets from the collision signal by successively decoding and canceling the demodulated signal. Another type of method, such as CoLoRa and CIC, infers the start and end times of each colliding chirp by tracking the ratio of energy peaks in adjacent demodulation windows, or by dividing the demodulation window and searching for common energy peaks. These methods assume that the start and end times of all colliding chirs are stable and predictable, and classify and demodulate chirs of different data packets based on this assumption.

[0027] The drawback of existing technology one is that it cannot effectively handle overlapping channel interference. For example... Figure 3As shown, in user-defined overlapping channel scenarios, the center frequency of interfering data packets is random and unknown, causing interfering chirps to only partially fall within the demodulation window of the target data packet. Therefore, the start and end times of the interfering chirps depend not only on the arrival time of the data packets but also on their random modulation symbols and center frequencies, becoming highly unpredictable. Existing methods, relying on peak energy ratios and common peak energy characteristics, cannot accurately infer chirp boundaries when start and end times are unknown, thus failing to achieve reliable concurrent demodulation. Furthermore, these methods typically require gateways to cache large amounts of I / Q samples and possess high computational power, making real-time demodulation at the local gateway impossible, resulting in high latency and cost.

[0028] Existing technologies primarily employ collision avoidance strategies rather than concurrent demodulation. These methods reduce the probability of collisions through centralized scheduling or carrier sensing. For example, some schemes centrally allocate the usage time or frequency resources of logical channels at the LoRa gateway, ensuring that at most one data packet is transmitted within the same logical channel at any given time. Other schemes implement a CSMA mechanism at the terminal node, where the node listens for channel idleness before transmitting; if idle, it transmits; otherwise, it backs off. These methods aim to fundamentally avoid collisions, rather than recovering after a collision occurs.

[0029] Existing technology two has significant drawbacks in dealing with overlapping channel interference. Firstly, centralized scheduling can only manage nodes within the same LoRa network. For multiple coexisting networks operated independently by different users, the gateway cannot coordinate resources across networks, thus failing to avoid overlapping channel interference from other networks, such as… Figure 4 As shown. Secondly, the CSMA mechanism significantly reduces channel utilization and transmission efficiency in densely deployed scenarios, and the issues of hidden and exposed terminals still lead to collisions. Therefore, collision avoidance methods cannot provide reliable and efficient packet reception performance in user-defined overlapping channel environments.

[0030] like Figure 1 and 2 As shown, this invention proposes a reliable real-time data packet reception method in a user-defined overlapping LoRa channel. The method is applied to a LoRa gateway, and the steps of the method include: Step S100: Obtain the original I / Q sampling signal received by the radio frequency front end, perform preamble detection on the original I / Q sampling signal using a sliding demodulation window, and determine the distribution of the preamble frequency domain energy peak based on the result of the preamble detection; like Figure 5As shown, in the specific implementation process, the original I / Q sampling signal is acquired through the radio frequency front end, and the target data packet identification stage is entered. The signal locking and frequency calibration are completed by comparing the preamble detection and carrier frequency offset (CFO). Subsequently, channel noise estimation is performed in the signal cancellation determination stage, and noise perception parameters are dynamically configured according to environmental characteristics. Next, the system enters the target chirp identification stage, and interference is eliminated through iterative signal cancellation technology, and the identification results are accurately corrected. Finally, the extracted data symbols are delivered to the upper-layer IoT application to realize reliable information transmission and service processing in the environment of overlapping channel interference.

[0031] Step S200: Determine the target data packet based on the distribution of the preamble frequency domain energy peak, determine the average signal-to-noise ratio based on multiple preamble chirped signals of the target data packet, and determine the candidate duration of the signal cancellation window according to the average signal-to-noise ratio and the pre-established signal-to-noise ratio-minimum distance threshold mapping relationship; In the specific implementation process, after detecting eight consecutive UpChirps, the currently detected data packet is taken as a candidate locked data packet, and despreading and Fast Fourier Transform are performed on the UpChirp and DownChirp in the preamble of the candidate locked data packet respectively. According to the frequency offset characteristics of commercial LoRa transceivers, if the candidate locked data packet belongs to the target data packet to be received by the gateway, its center frequency offset relative to the target center frequency is less than a preset offset threshold; if the candidate locked data packet comes from other user-defined overlapping channels, its center frequency offset relative to the target center frequency is larger. Based on this, the gateway checks whether there is an energy peak in the preset frequency band after DownChirp despreading; if not, the candidate locked data packet is determined to be an interference data packet and discarded; if it exists, the amplitude ratio of different energy peaks in the preset frequency band is further compared, and the candidate locked data packet with the amplitude ratio meeting the expected range is confirmed as the target data packet, and the starting position of the target Chirp is determined according to the preamble time position of the target data packet.

[0032] like Figure 6 As shown, in the specific implementation process, the LoRa gateway checks whether there is an energy peak in the 0 to 6 kHz frequency band after DownChirp despreading. If there is no energy peak in this frequency band, it means that the center frequency offset of the currently locked data packet does not meet the expected range of the target data packet, and the LoRa gateway determines the currently locked signal as an interference data packet and discards it. If there is an energy peak in this frequency band, the amplitude ratio of different energy peaks in this frequency band is further compared, and the data packet corresponding to the energy peak whose amplitude ratio meets the preset range is selected as the target data packet.

[0033] Step S300: Determine the actual signal cancellation location set based on the candidate duration, the starting position of the sliding demodulation window, and the maximum number of signal cancellations that the gateway can perform; In the specific implementation process, after locking onto the target data packet, the gateway measures the average signal-to-noise ratio of multiple UpChirps in the preamble of the target data packet. Based on the mapping relationship obtained beforehand through actual measurements, such as... Figure 7 As shown, the gateway determines the minimum and maximum distance thresholds that guarantee reliable demodulation at the current signal-to-noise ratio, and calculates the candidate duration required for signal cancellation accordingly. Then, starting from the beginning of the demodulation window, the gateway generates a series of candidate signal cancellation position pairs, each containing the start and end times of signal cancellation. The gateway also determines the maximum number of feasible signal cancellation attempts based on its computational capabilities and selects a subset of candidate positions for actual execution.

[0034] Step S400: For each signal cancellation position in the actual signal cancellation position set, the time domain signal of the corresponding time period is cancelled from the received signal in the current sliding demodulation window, and despreading and fast Fourier transform are performed on the cancelled residual signal to obtain the residual frequency domain energy peak distribution under the corresponding cancellation round. In the specific implementation process, such as Figure 8 As shown in (a) and (b), cross-channel collisions can cause multiple peaks within the decoding window, with the target energy peak located at the frequency point. However, its amplitude is lower than other interference peaks, therefore, the existing LoRa gateway decoding process cannot accurately identify the target peak. If some frequency points are removed, the peak values ​​of different chirs will exhibit distinguishable changes. For example... Figure 8 As shown in (c) and (d), we use a Wiper with a bandwidth of bw to erase the signal. Within the window, the target chirp fills the entire window; therefore, the portion of the target chirp erased with a bandwidth of 2bw can be calculated using the Wiper bandwidth and the signal bandwidth, leaving only half of the chirp remaining. Figure 8 In (d), the peak height of the target peak becomes half of its original value, and the peak height is reduced by 1 / 2. The peak value is 0.5. For interfering chirps that do not fill the entire window, their peak-to-peak ratio (PPR) is not equal to the expected value of 0.5. In summary, this scheme calculates the expected PPR of the target chirp using the Wiper bandwidth and takes the peak with the PPR closest to the expected PPR as the decoding result.

[0035] Step S500: Calculate the amplitude reduction ratio of the energy peak at each frequency point based on the residual frequency domain energy peak distribution, and determine the target energy peak corresponding to the current Chirp based on the deviation between the amplitude reduction ratio and the expected reduction ratio of the target Chirp. Step S600: Take the frequency point corresponding to the target energy peak as the demodulation result of the current Chirp, and repeat the target energy peak determination process until the demodulation of the target data packet payload is completed.

[0036] In the specific implementation process, target chirp identification is based on multi-round signal cancellation. For each selected signal cancellation location, the gateway cancels the time-domain signal of the corresponding time period from the received signal, and then performs despreading and Fast Fourier Transform on the remaining signal to obtain the peak energy amplitude at each frequency. The gateway calculates the amplitude reduction ratio of each energy peak, that is, the ratio of the amplitude after cancellation to the amplitude before cancellation. For the target chirp, since it completely occupies the entire demodulation window, its reduction ratio is a fixed value, equal to the ratio of the remaining window length to the original window length. For interfering chirps, due to their partial overlap, the reduction ratio is random and usually deviates from this fixed value. The gateway compares the deviation between the actual reduction ratio and the expected ratio of each energy peak and ranks the deviations of each energy peak in the multi-round signal cancellation. If an energy peak has the smallest deviation in more than half of the cancellation rounds, it is identified as the target energy peak; otherwise, the average amplitude of the energy peaks in the preamble is further introduced as an auxiliary feature, and the peak whose amplitude is closest to this average value is selected as the target energy peak. Finally, the frequency point corresponding to the target energy peak is taken as the demodulation result of the current Chirp, and the above process is repeated until the payload of the entire data packet is completely demodulated.

[0037] Using the above scheme, the LoRa gateway first locks onto the target data packet through joint verification of the preamble and center frequency offset, avoiding incorrect entry into the subsequent demodulation process when the interfering data packet arrives first or has higher energy. After the target data packet is locked, a limited number of time-domain signal cancellation positions are adaptively selected based on the current channel noise state, ensuring that each cancellation can generate a distinguishable amplitude reduction response to the target chirp and partially overlapping interfering chirps. Finally, the target energy peak is determined through multiple rounds of offset sorting and voting, thereby completing real-time demodulation without the need for accurate estimation of the start and end boundaries of the interfering chirp. In some embodiments of the present invention, in the step of determining the distribution of the preamble frequency domain energy peak based on the result of the preamble detection, after detecting a preset number of consecutive chirped signals, despreading and fast Fourier transform are performed on the chirped and lower chirped signals in the preamble, respectively, to obtain the distribution of the preamble frequency domain energy peak.

[0038] In some embodiments of the present invention, in the step of determining the target data packet based on the distribution of the preamble frequency domain energy peaks, it is checked whether there is an energy peak in the preset center frequency offset band after the lower chirp signal in the preamble is despread; if there is no energy peak, the currently determined data packet is determined to be an interference data packet and discarded; if there is an energy peak, the amplitude ratio of different energy peaks in the preset center frequency offset band is compared, and the data packet corresponding to the energy peak whose amplitude ratio falls within the preset amplitude ratio range is identified as the target data packet.

[0039] In some embodiments of the present invention, in the step of determining the average signal-to-noise ratio based on multiple preamble chirped signals of the target data packet, the average signal-to-noise ratio is calculated using the following formula: in, Indicates the average signal-to-noise ratio; Indicates the number of preamble chirps in the target data packet; This represents the signal-to-noise ratio corresponding to the chirped signal on the nth preamble.

[0040] In some embodiments of the present invention, in the step of determining the candidate duration of the signal cancellation window based on the average signal-to-noise ratio and the pre-established signal-to-noise ratio-minimum distance threshold mapping relationship, the candidate duration is calculated using the following formula: in, This represents the minimum distance threshold corresponding to the current average signal-to-noise ratio; This represents the signal-to-noise ratio-minimum distance threshold mapping relationship established in advance through actual measurements; Indicates the candidate duration of the signal cancellation window; This represents the total duration of a sliding demodulation window.

[0041] Specifically, channel noise causes the actual observed reduction rate to deviate from the theoretical value, and the degree of deviation... It increases as the signal-to-noise ratio decreases. To ensure reliable demodulation, a theoretical distance is required. satisfy .

[0042] like Figure 9 As shown, in some embodiments of the present invention, in the step of determining the actual signal cancellation location set based on the candidate duration, the starting position of the sliding demodulation window, and the maximum number of signal cancellations that the gateway can perform, Starting from the beginning position of the sliding demodulation window, the signal cancellation window is moved with a preset sampling step size to generate a set of candidate position pairs. Each candidate position pair in the set of candidate position pairs contains the start time and end time of signal cancellation. The LoRa gateway numbers the candidate position pairs in the candidate position pair set according to the order in which each candidate position pair appears in the sliding demodulation window. When the total number of candidate position pairs exceeds the maximum number of executable signal eliminations, all candidate position pairs are divided into multiple candidate segments corresponding to the maximum number of executable signal eliminations according to their numbering order. The LoRa gateway selects one candidate location pair from each candidate segment as the actual signal cancellation location pair, and forms an actual signal cancellation location set from the selected multiple actual signal cancellation location pairs.

[0043] In some embodiments of the present invention, the candidate position pair set is generated using the following formula: Where Ω represents the set of candidate position pairs; and These represent the start and end times of the m-th candidate signal elimination position pair, respectively. Indicates the start time of the sliding demodulation window. This represents the total duration of a sliding demodulation window.

[0044] In the specific implementation process, this will As a candidate duration for the signal cancellation window, the gateway from Initially, move the starting position of the signal cancellation window in steps (usually one sampling point). , to end position Generate a set of candidate position pairs ,in .

[0045] Considering the limited computing power of the gateway, let the maximum number of signal cancellations be [number]. Then from Medium interval selection One position, step size The actual execution location is common This enables adaptive noise cancellation location determination for noise perception.

[0046] In some embodiments of the present invention, in the step of calculating the amplitude reduction ratio of the energy peak at each frequency point based on the residual frequency domain energy peak distribution, the amplitude reduction ratio is determined using the following formula: in, Indicates the expected reduction rate of the target Chirp; This represents the duration of the elimination window corresponding to the j-th round of signal elimination; This represents the actual amplitude reduction rate of the energy peak value at the k-th frequency point after the j-th round of elimination; This represents the peak value of the residual frequency domain energy at the k-th frequency point after the j-th round of elimination; This represents the peak energy amplitude at the k-th frequency point before elimination; This represents the deviation value corresponding to the k-th frequency point in the j-th round of elimination.

[0047] In some embodiments of the present invention, in the step of determining the target energy peak corresponding to the current Chirp based on the deviation between the amplitude reduction ratio and the expected reduction ratio of the target Chirp, the deviation values ​​of each frequency point in each elimination round are sorted, and the number of times each frequency point becomes the minimum deviation frequency point is counted; if any frequency point corresponds to the minimum deviation value in more than half of the elimination rounds, the energy peak of that frequency point is determined as the target energy peak; otherwise, auxiliary correction is performed based on the average amplitude of the energy peak in the preamble of the target data packet, and the energy peak of the frequency point whose amplitude is closest to the average amplitude of the energy peak is determined as the target energy peak.

[0048] The beneficial effects of this plan include: 1. To achieve reliable data packet reception under overlapping channel interference, this scheme identifies the target chirp by comparing the reduction rate of the energy peak, without needing to know the precise start and end time of the interference chirp.

[0049] 2. In order to accurately identify and lock the target data packet in overlapping channel collisions, this scheme distinguishes the target packet from the interference packet by the frequency position and amplitude ratio of the energy peak after despreading up and down chirping.

[0050] 3. To address the impact of channel noise on demodulation reliability, this scheme dynamically determines the duration and candidate positions of the cancellation window based on the real-time measured signal-to-noise ratio, and combines multiple rounds of cancellation voting with absolute energy intensity to assist in correcting the demodulation results.

[0051] This invention also provides a reliable real-time data packet reception system in a user-defined overlapping LoRa channel. The system includes a computer device, which includes a processor and a memory. The memory stores computer instructions, and the processor executes the computer instructions stored in the memory. When the computer instructions are executed by the processor, the system implements the steps of the method described above.

[0052] This invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the aforementioned multimodal anomaly prediction method for logistics supply chains based on hybrid expert models. The computer-readable storage medium can be a tangible storage medium, such as random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, floppy disks, hard disks, removable storage disks, CD-ROMs, or any other form of storage medium known in the art.

[0053] Those skilled in the art will understand that the exemplary components, systems, and methods described in conjunction with the embodiments disclosed herein can be implemented in hardware, software, or a combination of both. Whether implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention. When implemented in hardware, it can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this invention are programs or code segments used to perform the desired tasks. The programs or code segments can be stored in a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried in a carrier wave.

[0054] It should be clarified that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of the present invention.

[0055] In this invention, features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with or in place of features of other embodiments.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations of the embodiments of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for reliable real-time data packet reception in user-defined overlapping LoRa channels, characterized in that, The method is applied to a LoRa gateway, and the steps of the method include: The raw I / Q sampled signal received by the radio frequency front end is acquired, and a preamble detection is performed on the raw I / Q sampled signal using a sliding demodulation window. The distribution of the preamble frequency domain energy peak is determined based on the result of the preamble detection. The target data packet is determined based on the distribution of the preamble frequency domain energy peak, the average signal-to-noise ratio is determined based on the multiple preamble chirped signals of the target data packet, and the candidate duration of the signal cancellation window is determined according to the average signal-to-noise ratio and the pre-established signal-to-noise ratio-minimum distance threshold mapping relationship. The actual signal cancellation location set is determined based on the candidate duration, the starting position of the sliding demodulation window, and the maximum number of signal cancellations that the gateway can perform. For each signal cancellation position in the actual signal cancellation position set, the time domain signal of the corresponding time period is eliminated from the received signal in the current sliding demodulation window, and despreading and fast Fourier transform are performed on the residual signal after cancellation to obtain the residual frequency domain energy peak distribution under the corresponding cancellation round. The amplitude reduction ratio of the energy peak at each frequency point is calculated based on the residual frequency domain energy peak distribution, and the target energy peak corresponding to the current Chirp is determined according to the deviation between the amplitude reduction ratio and the expected reduction ratio of the target Chirp. The frequency point corresponding to the target energy peak is used as the demodulation result of the current Chirp, and the target energy peak determination process is repeated until the demodulation of the target data packet payload is completed.

2. The method for reliable real-time data packet reception in user-defined overlaid LoRa channels according to claim 1, wherein, In the step of determining the distribution of the preamble frequency domain energy peak based on the preamble detection result, after detecting a preset number of consecutive chirped signals, despreading and fast Fourier transform are performed on the chirped and lower chirped signals in the preamble, respectively, to obtain the distribution of the preamble frequency domain energy peak.

3. The method for reliable real-time data packet reception in user-defined overlaid LoRa channels of claim 1, wherein, In the step of determining the target data packet based on the distribution of the preamble frequency domain energy peak, it is checked whether there is an energy peak in the preset center frequency offset frequency band after the lower chirp signal in the preamble is despread; if there is no energy peak, the currently determined data packet is determined to be an interference data packet and is discarded. If the energy peak exists, the amplitude ratio of different energy peaks within the preset center frequency offset band is compared, and the data packets corresponding to the energy peaks whose amplitude ratio falls within the preset amplitude ratio range are identified as target data packets.

4. The method for reliable real-time data packet reception in user-defined overlaid LoRa channels of claim 1, wherein, In the step of determining the average signal-to-noise ratio based on multiple preamble chirped signals of the target data packet, the average signal-to-noise ratio is calculated using the following formula: in, Indicates the average signal-to-noise ratio; Indicates the number of preamble chirps in the target data packet; This represents the signal-to-noise ratio corresponding to the chirped signal on the nth preamble.

5. The method for reliable real-time data packet reception in user-defined overlaid LoRa channels of claim 1, wherein, In the step of determining the candidate duration of the signal cancellation window based on the average signal-to-noise ratio and the pre-established signal-to-noise ratio-minimum distance threshold mapping relationship, the candidate duration is calculated using the following formula: in, This represents the minimum distance threshold corresponding to the current average signal-to-noise ratio; This represents the signal-to-noise ratio-minimum distance threshold mapping relationship established in advance through actual measurements; Indicates the candidate duration of the signal cancellation window; This represents the total duration of a sliding demodulation window.

6. The method for reliable real-time data packet reception in user-defined overlaid LoRa channels of claim 1, wherein, In the step of determining the actual signal cancellation location set based on the candidate duration, the starting position of the sliding demodulation window, and the maximum number of signal cancellations that the gateway can perform, the signal cancellation window is moved with a preset sampling step size starting from the starting position of the sliding demodulation window to generate a set of candidate location pairs. Each candidate location pair in the set of candidate location pairs contains the start time and end time of signal cancellation. The LoRa gateway numbers the candidate position pairs in the candidate position pair set according to the order in which each candidate position pair appears in the sliding demodulation window. When the total number of candidate position pairs exceeds the maximum number of executable signal eliminations, all candidate position pairs are divided into multiple candidate segments corresponding to the maximum number of executable signal eliminations according to their numbering order. The LoRa gateway selects one candidate location pair from each candidate segment as the actual signal cancellation location pair, and forms an actual signal cancellation location set from the selected multiple actual signal cancellation location pairs.

7. The method for reliable real-time data packet reception in user-defined overlaid LoRa channels of claim 6, wherein, The candidate position pair set is generated using the following formula: Where Ω represents the set of candidate position pairs; and These represent the start and end times of the m-th candidate signal elimination position pair, respectively. Indicates the start time of the sliding demodulation window. This represents the total duration of a sliding demodulation window.

8. The method for reliable real-time data packet reception in user-defined overlaid LoRa channels of claim 1, wherein, In the step of calculating the amplitude reduction ratio of the energy peak at each frequency point based on the residual frequency domain energy peak distribution, the amplitude reduction ratio is determined using the following formula: in, Indicates the expected reduction rate of the target Chirp; This represents the duration of the elimination window corresponding to the j-th round of signal elimination; This represents the actual amplitude reduction rate of the energy peak value at the k-th frequency point after the j-th round of elimination; This represents the peak value of the residual frequency domain energy at the k-th frequency point after the j-th round of elimination; This represents the peak energy amplitude at the k-th frequency point before elimination; This represents the deviation value corresponding to the k-th frequency point in the j-th round of elimination.

9. The method for reliable real-time data packet reception in user-defined overlaid LoRa channels of claim 1, wherein, In the step of determining the target energy peak corresponding to the current Chirp based on the deviation between the amplitude reduction rate and the expected reduction rate of the target Chirp, the deviation values ​​of each frequency point under each elimination round are sorted, and the number of times each frequency point becomes the minimum deviation frequency point is counted. If any frequency point corresponds to the minimum deviation value in more than half of the elimination rounds, then the energy peak value of that frequency point is determined as the target energy peak value; Otherwise, auxiliary correction is made based on the average amplitude of the energy peak in the preamble of the target data packet, and the energy peak at the frequency point whose amplitude is closest to the average amplitude of the energy peak is determined as the target energy peak.

10. A system for reliable real-time data packet reception in user-defined overlapping LoRa channels, characterized by, The system includes a computer device, which includes a processor and a memory. The memory stores computer instructions, and the processor executes the computer instructions stored in the memory. When the computer instructions are executed by the processor, the system implements the steps of the method as described in any one of claims 1 to 9.

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