A method and system for reducing harmonic interference in a multipath propagation environment

Abstract

The present invention belongs to the field of wireless communication technology and relates to a method and system for reducing harmonic interference in a multipath propagation environment. Add label identifiers to each signal component; generate a signal waveform diagram and an amplitude change amount for each signal component; obtain the similarity value between the standard sine waveform diagram and each signal waveform diagram; establish a mapping relationship between the similarity value and the amplitude change amount according to the label identifier; generate a first box plot according to the similarity value and a second box plot according to the amplitude change amount; extract the similarity values in the first box plot that exceed the end point of the lower whisker to obtain a first data set; extract the amplitude change amounts in the second box plot that exceed the end point of the upper whisker to obtain a second data set; determine whether there is one or more mapping relationships between the first data set and the second data set; if so, discard the signal components corresponding to each mapping relationship. The present invention can reduce harmonic interference in multipath propagation, reduce the consumption of computing resources at the receiving end, and reduce the difficulty of its signal processing.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication, and relates to a method and system for reducing harmonic interference in a multipath propagation environment. Background Art

[0002] In the field of wireless communication, harmonics are the other frequency components in a periodic signal except the fundamental frequency, and their frequencies are integer multiples of the fundamental frequency. Especially in a multipath propagation environment, the fundamental wave and its harmonic components of a signal will propagate to the receiving end through multiple different paths (such as direct wave, reflection, refraction, etc.), and each path signal contains the fundamental wave and its harmonic components. The harmonic signals may interact with the multipath components of the fundamental wave signal, resulting in an increase in the complexity of the received signal. Due to the multipath effect, these signals will be superimposed according to their respective phases, resulting in signal waveform distortion and reducing the signal quality at the receiving end. In addition, multipath propagation will cause frequency-selective fading of the signal in the frequency domain, affecting the amplitude and phase of the fundamental wave and harmonics.

[0003] Although harmonic waves can be suppressed at the transmitting end through filter technology, radio frequency front-end optimization, etc., since the generation of harmonic waves is closely related to the characteristics of nonlinear components, and the nonlinear characteristics of these components are difficult to completely eliminate, the signals transmitted from the transmitting end still contain harmonic waves. In order to further reduce harmonic interference, currently, signal processing technology, multi-carrier modulation technology, multi-antenna technology, frequency and time diversity technology, machine learning algorithms, etc. are mostly used at the receiving end to suppress harmonic waves. However, although the above technologies can effectively suppress the interference caused by harmonic waves, the effect is still not ideal. One of the reasons is that the complex signal propagation path, the interference between signals in the propagation path, and the signals from other non-target signal sources increase the number and complexity of the inferior signals at the receiving end, resulting in a large amount of computing resources being consumed when the receiving end processes signals, significantly increasing the signal processing difficulty and significantly reducing the signal processing efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that in a multipath propagation environment, the ability of the receiving end to process signals will be interfered by a large number of complex inferior signals, resulting in a large amount of computing resources being consumed when the receiving end processes signals, increasing the signal processing difficulty and reducing the signal processing efficiency.

[0005] The present invention is achieved by the following technical solutions:

[0006] In a first aspect, a method for reducing harmonic interference in a multipath propagation environment is proposed, including the following steps: receiving multiple signal components from multiple signal propagation paths; adding a label identifier to each signal component; the label identifier includes: reception time and antenna coordinates; generating a signal waveform diagram for each signal component; obtaining the similarity between the standard sine waveform diagram and each signal waveform diagram to obtain a similarity value corresponding to each signal waveform diagram; obtaining the amplitude change amount corresponding to each signal component; establishing a mapping relationship between the similarity value and the amplitude change amount according to the label identifier; generating a first box plot based on all the similarity values and a second box plot based on all the amplitude change amounts; extracting all the similarity values in the first box plot that exceed the end point of the lower whisker to obtain a first data set; extracting all the amplitude change amounts in the second box plot that exceed the end point of the upper whisker to obtain a second data set; determining whether there is one or more mapping relationships between the first data set and the second data set; if there is one or more mapping relationships, then discard the signal components corresponding to each mapping relationship.

[0007] In a second aspect, a system for reducing harmonic interference in a multipath propagation environment is proposed, including: a signal reception module for receiving multiple signal components from multiple signal propagation paths; a label adding module for adding a label identifier to each signal component; the label identifier includes: reception time and antenna coordinates; a signal processing module for generating a signal waveform diagram for each signal component and obtaining the amplitude change amount corresponding to each signal component; an image processing module for obtaining the similarity between the standard sine waveform diagram and each signal waveform diagram to obtain a similarity value corresponding to each signal waveform diagram; a relationship establishing module for establishing a mapping relationship between the similarity value and the amplitude change amount according to the label identifier; a numerical processing module for generating a first box plot based on all the similarity values, generating a second box plot based on all the amplitude change amounts, extracting all the similarity values in the first box plot that exceed the end point of the lower whisker to obtain a first data set, and extracting all the amplitude change amounts in the second box plot that exceed the end point of the upper whisker to obtain a second data set; a data analysis module for determining whether there is one or more mapping relationships between the first data set and the second data set; if there is one or more mapping relationships, then discard the signal components corresponding to each mapping relationship.

[0008] Compared with the prior art, the present invention has the following advantages and beneficial effects: On the one hand, in combination with the characteristics of harmonic waves causing signal waveform distortion, image processing technology is used to compare the waveform diagrams of the signal components of each path received at the receiving end with the standard sine waveform diagram, and the similarity is used to characterize the interference degree of harmonics on each propagation path. That is, the lower the similarity, the more obvious the signal waveform distortion and the greater the harmonic interference. On the other hand, in combination with the characteristic that the superposition interference of harmonic components in multipath propagation causes signal amplitude changes, a numerical analysis method is used to extract the amplitude change amount of the signal, and the magnitude of the amplitude change amount is used to characterize the interference degree of harmonics. That is, the greater the amplitude change amount of the signal, the greater the harmonic interference. Furthermore, based on the characteristic data extracted from the above two aspects, box plots are used to describe the data distribution characteristics of the similarity and the data distribution characteristics of the amplitude change amount, and the upper whisker and the lower whisker are used as the screening boundaries for abnormal data. If, after analysis, the similarity value and the amplitude change amount of the signal component on a certain propagation path are both outside the screening boundaries, it means that the signal component on this propagation path is significantly affected by harmonics, which will increase the difficulty of subsequent signal processing and can be discarded. After screening out all the signal components affected by harmonics according to the mapping relationship, the remaining signal components are used for signal processing. Finally, it is possible to effectively reduce the harmonic interference in multipath propagation, reduce the consumption of computing resources at the receiving end, reduce the difficulty of its signal processing, improve the signal processing efficiency, and ensure the signal quality at the receiving end. Description of the Drawings

[0009] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, form a part of this application, and do not limit the embodiments of the present invention. In the drawings:

[0010] Figure 1 It is a schematic flowchart of a method for reducing harmonic interference in a multipath propagation environment provided by an embodiment of the present invention.

[0011] Figure 2 It is a comparison diagram of the standard sine waveform diagram and the signal waveform diagram within one period after image segmentation provided by an embodiment of the present invention.

[0012] Figure 3 It is the standard sine waveform diagram after image segmentation and pixel point marking provided by an embodiment of the present invention. Detailed Embodiments

[0013] To make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to embodiments. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention. The following described embodiments are some of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0014] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that: the present invention does not have to employ these specific details. In other embodiments, well-known structures, materials, or methods are not specifically described in order to avoid obscuring the present invention. The materials, instruments, reagents, etc. used in the following embodiments can be obtained from commercial sources without special instructions. The technical means used in the embodiments are conventional means well-known to those of ordinary skill in the art without special instructions.

[0015] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality" means two or more unless specifically defined otherwise.

[0016] Embodiment 1: A method for reducing harmonic interference in a multipath propagation environment is proposed, including Figure 1 the following steps:

[0017] Step 1: Generate a target signal source identification code at the transmitting end and add the target signal source identification code to the transmitted signal.

[0018] The target signal source identification code can be used by the receiving end to identify the source of each received signal component. When the received signal component does not contain a signal source identification code, or the signal source identification code contained in the received signal component does not match the target source signal identification code, it indicates that the received signal component comes from other transmitting ends.

[0019] Among them, the method for generating the target signal source identification code is:

[0020] Step 1.1: Extract I / Q samples from the transmitted signal.

[0021] I / Q samples (I / Q samples are the sampled data after decomposing a signal into two orthogonal components. Among them, the I component represents the component with the same phase as the signal, corresponding to a cosine wave; the Q component represents the component with a phase difference of 90 degrees from the signal, corresponding to a sine wave.) Representing the collected desired signal in complex form can completely describe the amplitude and phase information of the signal. By extracting I / Q samples, the signal can be transformed from the time domain to complex form, providing basic data for subsequent matrix transformation and feature extraction.

[0022] Step 1.2: Normalize the I / Q samples.

[0023] Step 1.3: Convert the I / Q samples into a two-dimensional matrix.

[0024] Converting one-dimensional I / Q samples into a two-dimensional matrix can more intuitively represent the structure and changes of the signal. The two-dimensional matrix is convenient for matrix operations and visualization processing, providing a data structure for gradient calculation.

[0025] Step 1.4: Extract the time-frequency features in the transmitted signal through wavelet transform or short-time Fourier transform.

[0026] Step 1.5: Obtain the gradient matrix of the two-dimensional matrix.

[0027] The gradient matrix reflects the rate of change and direction of each point in the two-dimensional matrix, can highlight the edge and change features of the signal, and provides key information for subsequent model matching.

[0028] Step 1.6: For each I / Q sample, obtain the cumulative distance between the gradient matrix and multiple preset model gradient matrices.

[0029] By calculating the cumulative distance, the similarity between the signal gradient matrix and the preset model gradient matrix can be quantified. The smaller the cumulative distance, the higher the matching degree between the signal and the model.

[0030] Step 1.7: Screen out the model gradient matrix with the smallest cumulative distance from the I / Q samples.

[0031] Screen out the most matching model gradient matrix for subsequent feature extraction to ensure that the selected model gradient matrix can most accurately describe the features of the signal.

[0032] Step 1.8: Use the eigenvector corresponding to the screened model gradient matrix as the target signal source identification code.

[0033] The eigenvector is the unique identifier of the signal, can be used to distinguish different signal sources, and the target signal source identification code can be used for signal identification, classification and tracking. Generate a unique signal source identification code through the eigenvector.

[0034] Step 2: Use an antenna array to receive multiple signal components from multiple signal propagation paths.

[0035] In a wireless communication environment, a signal may travel through multiple paths from the transmitter to the receiver, including direct paths (LOS), reflection paths (such as ground reflection, building reflection), refraction paths (such as atmospheric refraction), and scattering paths. The lengths and propagation conditions of these paths are different, resulting in different arrival times and amplitudes of the signal at the receiver. When signals from different paths are superimposed at the receiver, due to propagation delays and phase differences, the amplitude of the signal may be enhanced (coherent enhancement) or weakened (coherent attenuation). The signal receiver uses equalization techniques, RAKE reception techniques, diversity techniques, multiple-input multiple-output (MIMO) techniques, orthogonal frequency division multiplexing (OFDM) techniques, etc. to receive signals propagating along multiple paths and perform selection combining and subsequent signal processing on the received signals. Commonly used methods include: maximum ratio combining, selective combining, multi-hop coherent combining assisted by cross-entropy iteration, etc. In this step, multiple antenna elements of the array antenna receive signals, and each element can receive signal components from different paths.

[0036] Step 3: Identify the signal source identification code for each signal component, and retain or discard the signal component according to the identification result.

[0037] It includes the following two steps:

[0038] Step 3.1: Decode the signal component.

[0039] Step 3.2: Determine whether the decoded signal component contains a signal source identification code. If it does not contain a signal source identification code, discard the signal component. If it contains a signal source identification code, determine whether the signal source identification code is the same as the target signal source identification code. If they are not the same, discard the signal component. If they are the same, retain the signal component.

[0040] After Step 3, first eliminate the signals from non-target signal sources, which can reduce the number of signal components received by the receiver and reduce complexity.

[0041] Step 4: Add a label identifier to each signal component.

[0042] For the convenience of subsequent processing of each signal component, in this embodiment, a label identifier is added to each signal component. Since the lengths and propagation conditions of the paths are different, the arrival times of the signals at the receiving end are different. Therefore, the arrival time of the signal component of a certain propagation path at the receiving end is used as one of the flags to identify the signal component of this path; and since each signal component arrives at the signal receiving end along different propagation paths, the azimuth of the signal component of a certain path arriving at the receiving end is used as another flag to identify the signal component of this path, and this azimuth can be represented by the coordinates of the corresponding antenna element in the antenna array; combining time and azimuth can uniquely identify the signal component of a certain path.

[0043] Step 5: Generate the signal waveform diagram of each signal component.

[0044] Calling software such as Excel, Python, and MATLAB can draw the signal waveform diagram of each signal component.

[0045] Step 6: Obtain the similarity between the standard sine waveform diagram and each signal waveform diagram, and obtain the similarity value corresponding to each signal waveform diagram.

[0046] Harmonic interference usually causes waveform distortion, resulting in irregular deformation of the signal waveform. The greater the degree of harmonic interference, the more serious the distortion of the signal waveform. The sine wave is an ideal signal form. Therefore, the standard sine waveform diagram and the signal waveform diagram are used for similarity comparison, and the similarity is used to characterize the degree of harmonic interference.

[0047] The method for obtaining the similarity value includes the following steps:

[0048] Step 6.1: Align the standard sine waveform diagram and each signal waveform diagram using timestamps.

[0049] In a multipath propagation environment, the signal components of different paths will have differences due to propagation delay. For the convenience of similarity comparison, it is necessary to align the signal components from different propagation paths and the standard sine wave to compensate for the time delay of the signals of different paths. In this embodiment, a timestamp is added to each signal component, and then the signals of different paths are aligned to the same time axis through the Cross-Correlation algorithm. Cross-Correlation is a commonly used signal alignment method for comparing the similarity of two signals in time and finding the best alignment position.

[0050] Step 6.2: Adjust the image attributes of the aligned standard sine waveform diagram to be consistent with the image attributes of each aligned signal waveform diagram.

[0051] Among them, the image attribute refers to the image size and image pixels.

[0052] Step 6.3: Perform mesh division on the adjusted standard positive waveform diagram and each adjusted signal waveform diagram, so that one mesh corresponds to one pixel point.

[0053] In this embodiment, the sawtooth wave and the standard sine wave are used as comparison objects. After mesh division, the waveform diagrams of the sawtooth wave and the sine wave are compared within one period as Figure 2 shown.

[0054] Step 6.4: Process the mesh-divided standard sine waveform diagram to obtain a first numerical sequence; process each mesh-divided signal waveform diagram to obtain a second numerical sequence.

[0055] The image processing mentioned in this step specifically includes the following steps:

[0056] Step A1: Set the value of the pixel points without waveform to 0, and set the value of the pixel points with waveform to 1.

[0057] Step A2: Extract the pixel values of each column of pixel points in the order from top to bottom to obtain the corresponding pixel value array.

[0058] Step A3: Concatenate the pixel value arrays of each column together in the order from left to right.

[0059] For example: For the mesh-divided standard sine waveform diagram, the sine waveform diagram after being processed by Step A1 is as Figure 3 shown; the multiple pixel value arrays obtained after being processed by Step A2 are: (0, 0, 1, 1, 1, 0, 0, 0, 0, 0), (0, 1, 1, 0, 0, 0, 0, 0, 0),......, (0, 0, 0, 0, 1, 1, 0, 0, 0, 0); the first numerical sequence obtained after being processed by Step A3 is: 00111000000110000000......0000110000.

[0060] Step 6.5: Process each second numerical sequence to obtain the corresponding similarity value.

[0061] The processing of the sequence mentioned in this step specifically includes the following steps:

[0062] B1: Starting from the end of the sequence, compare the pixel values of the second numerical sequence with those of the first numerical sequence one by one, and count the number of different digit positions.

[0063] B2: Obtain the ratio between the number of digit positions and the length of the first numerical sequence.

[0064] For example, after counting by Step B1, the number of different digit positions is 10, and the length of the first numerical sequence is 100, then the similarity is 0.1.

[0065] Step 7: Obtain the amplitude change amount corresponding to each signal component.

[0066] The amplitude change amount described in this step is the difference between the absolute value of the minimum amplitude value and the absolute value of the maximum amplitude value.

[0067] Step 8: Establish a mapping relationship between the similarity value and the amplitude change amount according to the label identification.

[0068] The calculated similarity value and amplitude change amount both refer to the signal components of the same propagation path. Therefore, the mapping relationship between the similarity value and the amplitude change amount is established using the label identification of this signal component.

[0069] Step 9: Generate a first box plot based on all the similarity values, and generate a second box plot based on all the amplitude change amounts.

[0070] A box plot is used to display the distribution of a set of data, intuitively presenting information such as the central tendency, dispersion degree, and outliers of the data. The "whiskers" in the box plot extend from the upper and lower boundaries of the box, representing the normal range of the data. The upper whisker represents the upper limit of the normal value range, and the lower whisker represents the lower limit of the normal value range. Data points outside the range of the whiskers are considered outliers, and outliers may be extreme values or error values in the data.

[0071] Step 10: Extract all the similarity values in the first box plot that exceed the end point of the lower whisker line to obtain a first data set; extract all the amplitude change amounts in the second box plot that exceed the end point of the upper whisker line to obtain a second data set.

[0072] The lower the similarity between the waveform diagram of the signal component and the standard sine waveform diagram, the greater the harmonic interference suffered by the signal; then the similarity value exceeding the end point of the lower whisker line indicates that the similarity exceeds the normal range. Similarly, the greater the amplitude change amount, the greater the harmonic interference suffered by the signal; then the amplitude change amount exceeding the end point of the upper whisker line indicates that the similarity exceeds the normal range.

[0073] Step 11: Determine whether there is one or more mapping relationships between the first data set and the second data set; if there is one or more mapping relationships, discard the signal components corresponding to each mapping relationship.

[0074] The first data set contains all the similarity values that exceed the end point of the lower whisker line, and the second data set contains all the amplitude change amounts that exceed the end point of the upper whisker line. If there is one or more mapping relationships between the first data set and the second data set, it means that there are signal components of one or more propagation paths with severe waveform distortion and significant amplitude changes. The signal components of this one or more propagation paths belong to inferior signals, which are not conducive to subsequent signal processing and need to be discarded.

[0075] Embodiment 2: Corresponding to the method provided in the above Embodiment 1, this embodiment provides a system for reducing harmonic interference in a multipath propagation environment, including: a signal receiving module for receiving a plurality of signal components from a plurality of signal propagation paths; a tag adding module for adding a tag identifier to each signal component; the tag identifier includes: reception time and antenna coordinates; a signal processing module for generating a signal waveform diagram of each signal component and obtaining the amplitude change amount corresponding to each signal component; an image processing module for obtaining the similarity between the standard sine waveform diagram and each signal waveform diagram to obtain the similarity value corresponding to each signal waveform diagram; a relationship establishing module for establishing a mapping relationship between the similarity value and the amplitude change amount according to the tag identifier; a numerical processing module for generating a first box plot according to all the similarity values, generating a second box plot according to all the amplitude change amounts, extracting all the similarity values in the first box plot that exceed the end point of the lower whisker to obtain a first data set, and extracting all the amplitude change amounts in the second box plot that exceed the end point of the upper whisker to obtain a second data set; a data analysis module for determining whether there is one or more mapping relationships between the first data set and the second data set; if there is one or more mapping relationships, then discard the signal components corresponding to each mapping relationship.

[0076] Further, the image processing module includes: a preprocessing unit for aligning the standard sine waveform diagram and each signal waveform diagram using a timestamp, adjusting the image attributes of the aligned standard sine waveform diagram to be consistent with the image attributes of each aligned signal waveform diagram, performing grid division on the adjusted standard sine waveform diagram and each adjusted signal waveform diagram, and corresponding one grid to one pixel point; wherein, the image attributes include: image size and image pixels; a first control unit for controlling the pixel setting unit, the pixel extraction unit, and the data splicing unit to process the grid-divided standard sine wave diagram to obtain a first numerical sequence, and calling the pixel setting unit, the pixel extraction unit, and the data splicing unit to process each grid-divided signal waveform diagram to obtain a second numerical sequence corresponding to each signal waveform diagram; the pixel setting unit for setting the value of the pixel point without a waveform to 0 and setting the value of the pixel point with a waveform to 1; the pixel extraction unit for extracting the pixel values of each column of pixel points in order from top to bottom to obtain a corresponding pixel value array; the data splicing unit for splicing the pixel value arrays of each column together in order from left to right; a second control unit for controlling the numerical comparison unit and the numerical calculation unit to process each second numerical sequence to obtain the corresponding similarity value; the numerical comparison unit for starting from the end of the sequence, comparing the pixel values of the second numerical sequence with the first numerical sequence one by one, and counting the number of different pixel points; the numerical calculation unit for obtaining the ratio between the number of different pixel points and the length of the first numerical sequence.

[0077] Further, the system further includes: an identification code generation module, configured to generate a target signal source identification code at the transmitting end; a signal modulation module, configured to add the target signal source identification code to the transmitted signal; a signal processing module, configured to call a signal decoding module and an analysis and processing module to process each signal component; a signal decoding module, configured to decode the signal component; an analysis and processing module, configured to determine whether the decoded signal component contains a signal source identification code. If the signal component does not contain a signal source identification code, the signal component is discarded. If the signal component contains a signal source identification code, it is determined whether the signal source identification code is consistent with the target signal source identification code. If they are not consistent, the signal component is discarded. If they are consistent, the signal component is retained.

[0078] Further, the identification code generation module includes: a sample extraction unit, configured to extract I / Q samples from the transmitted signal; a sample processing unit, configured to convert the I / Q samples into a two-dimensional matrix; a matrix processing unit, configured to obtain the gradient matrix of the two-dimensional matrix; a distance acquisition unit, configured to obtain the cumulative distance between the gradient matrix and a plurality of preset model gradient matrices for each I / Q sample; a matrix screening unit, configured to screen out the model gradient matrix with the smallest cumulative distance from the I / Q sample, and use the eigenvector corresponding to the screened model gradient matrix as the target signal source identification code.

[0079] A system for reducing harmonic interference in a multipath propagation environment provided in this embodiment implements the method described in Embodiment 1 in a digital manner. Therefore, the working principles and effects of the functional modules and functional units in this system can be referred to the description in Embodiment 1 and will not be elaborated here.

[0080] It should be understood that the "system", "device", "unit" and / or "module" used in this specification are a way to distinguish different components, elements, parts, portions or assemblies at different levels. However, if other words can achieve the same purpose, the said words can be replaced by other expressions.

[0081] As shown in this specification and the claims, unless the context clearly indicates an exceptional situation, words such as "a", "an", "one" and / or "the" are not specifically singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of the clearly identified steps and elements, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0082] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0083] It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the implementation conditions of the present invention. Therefore, they do not have a technical essence. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the efficacy that the present invention can produce and the purpose that can be achieved, should still fall within the scope that can be covered by the technical content disclosed in the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle", etc. cited in this specification are only for the convenience of clear narration and are not used to limit the implementation scope of the present invention. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the implementable scope of the present invention.

Claims

1. A method for reducing harmonic interference in a multipath propagation environment, characterized in that: The following steps are involved: receiving a plurality of signal components from a plurality of signal propagation paths; Add a label to each signal component; the label includes: receiving time and antenna coordinates; generating a signal waveform diagram of each signal component; Obtaining the similarity between the standard sine waveform and each signal waveform, and obtaining the similarity value corresponding to each signal waveform; Obtain the amplitude change corresponding to each signal component; Establish a mapping relationship between the similarity value and the amplitude change according to the label identification; Generate a first box plot based on all similarity values, and generate a second box plot based on all amplitude changes; Extract all similarity values ​​exceeding the end point of the lower whisker in the first box plot to obtain a first data set; extract all amplitude changes exceeding the end point of the upper whisker in the second box plot to obtain a second data set; It is determined whether one or more mapping relationships exist between the first data set and the second data set; if one or more mapping relationships exist, a signal component corresponding to each mapping relationship is discarded.

2. The method for reducing harmonic interference in a multipath propagation environment according to claim 1, characterized in that: The method for obtaining a similarity value comprises the following steps: Aligning the standard sine waveform diagram with each signal waveform diagram using time stamps; Adjust the image attributes of the aligned standard sine waveform image to be consistent with the image attributes of each aligned signal waveform image; the image attributes include: image size and image pixels; Divide the adjusted standard positive waveform and each adjusted signal waveform into grids; one grid corresponds to one pixel point; A1-A3 is executed on the standard sine wave graph after grid division to obtain a first numerical sequence; A1-A3 is executed on each signal waveform graph after grid division to obtain a second numerical sequence corresponding to each signal waveform graph; wherein, A1: sets the value of the pixel point without waveform to 0, and sets the value of the pixel point with waveform to 1; A2: extracts the pixel value of each column of pixel points from top to bottom to obtain the corresponding pixel value array; A3: splices the pixel value arrays of each column together in sequence from left to right; Execute B1-B2 for each second numerical sequence to obtain the corresponding similarity value; wherein, B1: starting from the end of the sequence, compare the pixel values ​​of the second numerical sequence with the first numerical sequence one by one, and count the number of points with all different values; B2: obtain the ratio between the number of points and the length of the first numerical sequence.

3. A method for reducing harmonic interference in a multipath propagation environment according to claim 1 or 2, characterized in that: The amplitude change is the difference between the absolute value of the minimum amplitude value and the absolute value of the maximum amplitude value.

4. The method for reducing harmonic interference in a multipath propagation environment according to claim 1 or 2, characterized in that: Before receiving multiple signal components from multiple signal propagation paths, the method further includes the following steps: generating a target signal source identification code at a transmitting end; adding the target signal source identification code to the transmitted signal; Before adding a label to each signal component, the following steps are also included: Execute C1-C2 for each signal component; wherein, C1: decode the signal component; C2: determine whether the decoded signal component contains a signal source identification code, if not, discard the signal component; if it contains a signal source identification code, determine whether the signal source identification code is consistent with the target signal source identification code, if not, discard the signal component; if consistent, retain the signal component.

5. The method for reducing harmonic interference in a multipath propagation environment according to claim 4, characterized in that: The method for generating a target signal source identification code comprises the following steps: Extracting I / Q samples from the transmitted signal; Convert I / Q samples into a two-dimensional matrix; Get the gradient matrix of a two-dimensional matrix; For each I / Q sample, obtaining the cumulative distance between the gradient matrix and a plurality of preset model gradient matrices; Filter out the model gradient matrix with the smallest cumulative distance to the I / Q samples; The eigenvector corresponding to the screened model gradient matrix is ​​used as the target signal source identification code.

6. The method for reducing harmonic interference in a multipath propagation environment according to claim 5, characterized in that: Before converting the I / Q samples into a two-dimensional matrix, the following steps are also included: normalizing the I / Q samples; After the I / Q samples are converted into a two-dimensional matrix, the following steps are also included: extracting the time-frequency characteristics of the transmitted signal through wavelet transform or short-time Fourier transform.

7. A system for reducing harmonic interference in a multipath propagation environment, characterized in that: include: A signal receiving module, used for receiving a plurality of signal components from a plurality of signal propagation paths; A label adding module, used for adding a label identification to each signal component; Tag identification includes: receiving time and antenna coordinates; A signal processing module, used to generate a signal waveform diagram of each signal component and obtain an amplitude change corresponding to each signal component; An image processing module is used to obtain the similarity between the standard sine waveform and each signal waveform, and obtain the similarity value corresponding to each signal waveform; A relationship building module is used to establish a mapping relationship between a similarity value and an amplitude change amount according to a tag identifier; A numerical processing module, used to generate a first box plot according to all similarity values, generate a second box plot according to all amplitude changes, extract all similarity values ​​exceeding the end point of the lower whisker in the first box plot to obtain a first data set, and extract all amplitude changes exceeding the end point of the upper whisker in the second box plot to obtain a second data set; The data analysis module is used to determine whether there are one or more mapping relationships between the first data set and the second data set; if there are one or more mapping relationships, the signal component corresponding to each mapping relationship is discarded.

8. The system for reducing harmonic interference in a multipath propagation environment according to claim 7, characterized in that: The image processing module includes: A preprocessing unit is used to align the standard sine waveform with each signal waveform using a timestamp, adjust the image attributes of the aligned standard sine waveform to be consistent with the image attributes of each aligned signal waveform, divide the adjusted standard sine waveform and each adjusted signal waveform into grids, and correspond one grid to one pixel; wherein the image attributes include: image size and image pixels; A first control unit is used to control the pixel setting unit, the pixel extraction unit and the data splicing unit to process the standard sine wave graph after grid division to obtain a first numerical sequence, and to call the pixel setting unit, the pixel extraction unit and the data splicing unit to process each signal waveform graph after grid division to obtain a second numerical sequence corresponding to each signal waveform graph; A pixel setting unit, used to set the value of a pixel point without a waveform to 0, and set the value of a pixel point with a waveform to 1; A pixel extraction unit is used to extract the pixel values ​​of each column of pixels in order from top to bottom to obtain a corresponding pixel value array; A data splicing unit is used to sequentially splice the pixel value arrays of each column together in order from left to right; A second control unit, used for controlling the numerical comparison unit and the numerical calculation unit to process each second numerical sequence to obtain a corresponding similarity value; A value comparison unit is used to compare the pixel values ​​of the second value sequence with the first value sequence one by one starting from the end of the sequence, and count the number of points with different values; The numerical calculation unit is used to obtain the ratio between the number of points and the length of the first numerical sequence.

9. A system for reducing harmonic interference in a multipath propagation environment according to claim 7 or 8, characterized in that: Also includes: An identification code generation module, used to generate a target signal source identification code at the transmitting end; A signal modulation module, used to add a target signal source identification code to the transmission signal; A signal processing module, used to call a signal decoding module and an analysis processing module to process each signal component; A signal decoding module, used for decoding signal components; The analysis and processing module is used to determine whether the decoded signal component contains a signal source identification code. If not, the signal component is discarded. If it contains a signal source identification code, it is determined whether the signal source identification code is consistent with the target signal source identification code. If not, the signal component is discarded. If consistent, the signal component is retained.

10. The system for reducing harmonic interference in a multipath propagation environment according to claim 9, characterized in that: The identification code generation module includes: A sample extraction unit, used to extract I / Q samples from the transmitted signal; A sample processing unit, used for converting I / Q samples into a two-dimensional matrix; A matrix processing unit, used for obtaining a gradient matrix of a two-dimensional matrix; A distance acquisition unit, used for acquiring, for each I / Q sample, a cumulative distance between the gradient matrix and a plurality of preset model gradient matrices; The matrix screening unit is used to screen out the model gradient matrix with the smallest cumulative distance from the I / Q samples, and use the eigenvector corresponding to the screened model gradient matrix as the target signal source identification code.

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