A method for measuring and modeling the transmission channel of surface waves excited by metal pipes

Abstract

The present invention provides a method for measuring and modeling a surface wave transmission channel excited by a metal pipe. First, the coupling effect between a metal conductor and a medium is utilized to excite surface waves through a metal pipe commonly used in an industrial Internet of Things environment, thereby generating a surface wave channel that effectively reduces path loss. Then, the communication channel generated by the surface waves excited by metal pipes of different structures is measured and modeled. For orthogonal pipe structures with poor channel conditions, a conductor is introduced as compensation to optimize the channel characteristics. The method of the present invention effectively reduces the loss of the signal during transmission in this scenario, and by testing the channel transmission performance after introducing surface waves into metal pipes of different structures, it is concluded that the surface waves have different degrees of optimization effects on system performance when the metal pipes are in different structures and states. In addition, when the optimization effect of surface waves excited by metal pipes of certain structures is limited, the system performance is further optimized by artificially introducing compensation.

Description

Technical Field

[0001] The invention belongs to the technical field of wireless communications, and in particular relates to a method for measuring and modeling a metal pipe excited surface wave transmission channel. Background Art

[0002] Industrial Internet of Things (IIoT) is an application example of 5G and beyond 5G (B5G) technologies empowering industrial manufacturing, and is also the key foundation for industrial production to move from manufacturing to smart manufacturing. In order to achieve efficient integration of 5G and B5G with IIoT, it is necessary to study the channel propagation characteristics in different IIoT scenarios and establish a model that can accurately describe the wireless channel in different IIoT scenarios. Among them, the communication environment is a key factor affecting the wireless channel. Compared with traditional indoor office scenarios, IIoT scenarios are diverse and complex. The diversity is reflected in the different communication environments in factories producing different products, and the differences in channel characteristics between different functional areas in the same factory. The complexity is reflected in the different materials, layouts, shapes, and sizes of items inside the factory, as well as the complex electromagnetic environment brought about by the working machines and equipment. The diversity and complexity of IIoT scenarios make it impossible to use the channel model describing the indoor office scene to describe the wireless channel of the Industrial Internet of Things scene. Therefore, it is necessary to analyze and model the channel characteristics of the IIoT scene. In addition, the IIoT channel characteristics have obvious scene dependence. The channels in IIoT scenes of different types and sizes show different characteristics. In the same scene, it can be divided into different sub-scenes according to the scatterer density and antenna height. The channels of each sub-scene also have obvious differences.

[0003] Surface waves refer to electromagnetic waves that propagate along the surface of a medium. Their electromagnetic fields are mainly concentrated near the surface of the medium, and can cause a strong electromagnetic field distribution on the surface of the medium. In practical applications, different excitation methods will have different effects on the excitation position, polarization direction, wavelength and other characteristics of the surface wave. In a surface wave channel, the path loss of signal transmission is usually lower than that of a wireless channel. This is mainly because the reflection and refraction of the signal between the medium and the conductor will cause part of the signal energy to focus on the surface of the conductor, thereby reducing the loss to a certain extent. However, it should be noted that since the transmission of the surface wave channel is affected by many factors such as the shape of the conductor surface and the properties of the medium, in order to achieve the best transmission effect in practical applications, its transmission characteristics need to be accurately measured and modeled. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to test and model the transmission performance of surface waves in an industrial Internet of Things environment with metal pipes. By introducing a surface wave channel into an industrial Internet of Things environment with metal pipes, the signal loss during transmission in this scenario is effectively reduced. By testing the channel transmission performance after introducing surface waves into metal pipes with different structures, it is concluded that the surface waves have different degrees of optimization effects on system performance when the metal pipes are in different structures and states. In addition, when the optimization effect of surface waves excited by metal pipes with certain structures is limited, the system performance is further optimized by artificially introducing compensation.

[0005] The present invention specifically provides a method for measuring and modeling a metal pipe excited surface wave transmission channel, comprising the following steps:

[0006] Step 1, simulating a real industrial Internet of Things scenario, establishing a straight hollow metal pipe excited surface wave system model, setting a measurement scenario, and measuring the channel transmission characteristics of the system model;

[0007] Step 2, obtaining the data measured in step 1, and calculating the average path loss value of each measurement point;

[0008] Step 3: Construct the surface wave path loss attenuation value caused by the coupling distance in the scenario of surface waves excited by a straight metal pipe About coupling distance The parameter function model uses nonlinear least squares method to fit the parameters, and we get About coupling distance function and tested it by the residual sum of squares SSE;

[0009] Step 4: Based on the path loss index values ​​and coupling distances at different coupling distances, the path loss index based on different coupling distances in the straight metal pipe excitation surface wave scenario is constructed. About coupling distance The parameter function model uses nonlinear least squares method to fit the parameters, and we get About coupling distance function, and tested by the residual sum of squares SSE;

[0010] Step 5, construct a channel path loss model of wireless communication combined with surface waves in a straight metal pipe excitation surface wave scenario, use nonlinear least squares method to fit parameters, and perform data verification;

[0011] Step 6, simulating a real industrial Internet of Things scenario, constructing an orthogonal hollow metal pipe excited surface wave system model, setting a measurement scenario, and measuring the channel transmission characteristics of the system model;

[0012] Step 7, obtaining the data measured in step 6, and calculating the average path loss value of each measurement point;

[0013] Step 8: Construct the surface wave path loss attenuation value caused by the coupling distance in the orthogonal metal pipe excitation surface wave scenario About coupling distance The parameter function model uses nonlinear least squares method to fit the parameters, and we get About coupling distance function and perform data verification;

[0014] Step 9: Based on the path loss index values ​​and coupling distances at different coupling distances, the path loss index based on different coupling distances in the orthogonal metal pipe excitation surface wave scenario is constructed. About coupling distance The parameter function model uses nonlinear least squares method to fit the parameters, and we get About coupling distance function and perform data verification;

[0015] Step 10, constructing a channel path loss model of wireless communication combined with surface waves in a scenario of orthogonal metal pipes exciting surface waves, fitting parameters using a nonlinear least squares method, and performing data verification;

[0016] Step 11, comparing the channel model obtained in step 1 and step 10 with the free space transmission channel model, and designing a scheme to optimize the channel transmission characteristics of surface waves excited by orthogonal metal pipes using copper wires;

[0017] Step 12, constructing an orthogonal metal pipe excited surface wave system model introducing copper wire compensation according to the scheme designed in step 11, setting a measurement scene, and measuring the channel transmission characteristics of the system model;

[0018] Step 13, obtaining the data measured in step 12, and calculating the average path loss value of each measurement point;

[0019] Step 14: construct the surface wave path loss attenuation value caused by the coupling distance in the scenario of orthogonal metal pipe excitation surface wave with the copper wire introduced as compensation About coupling distance The parameter function model is fitted using the nonlinear least squares method, and the results are About coupling distance function and perform data verification;

[0020] Step 15, based on the path loss index values ​​and coupling distances at different coupling distances, construct a path loss index based on different coupling distances in a scenario where an orthogonal metal pipe excites a surface wave and introduces a copper conductor as compensation. About coupling distance The parameter function model uses nonlinear least squares method to fit the parameters, and we get About coupling distance function and perform data verification;

[0021] Step 16, construct a channel path loss model of wireless communication combined with surface waves in a scenario where copper wires are introduced as compensation for orthogonal metal pipe-excited surface waves, use nonlinear least squares method to fit parameters, and perform data verification.

[0022] In step 1, the straight hollow metal pipe excitation surface wave system model includes two planar magnetic dipole antennas, a straight hollow metal pipe and a pair of coupling devices with adjustable distance;

[0023] The two planar magnetic dipole antennas are used for transmitting and receiving signals respectively. The planar magnetic dipole antenna is an antenna with a transmitting angle and a receiving angle both greater than 30 degrees. It is a wide beam antenna, and its main feature is a wider main lobe and smaller side lobes.

[0024] The distance-adjustable coupling device is used to control the distance between the metal pipe and the antenna;

[0025] The hollow metal pipe serves as a medium for signal transmission and connects two planar magnetic dipole antennas;

[0026] The coupling device adopts an adjustable structure, including two layers of PVC boards and a height control bracket. The antenna is located between the two layers of PVC boards and is close to the lower PVC board. The four corners of the upper and lower PVC boards are fixed with screws. The distance between the hollow metal pipe and the antenna can be changed by adjusting the height control bracket. The distance between the hollow metal pipe and the antenna is the coupling distance.

[0027] Mechanism of signal transmission: In the wireless channel measurement system of the present invention, a part of the signal is still transmitted through the wireless channel, but most of the signal is transmitted to the receiving antenna along the surface of the hollow metal pipe in the form of surface waves.

[0028] The setting of the measurement scene includes: fixing the transmitting end and the receiving end of the antenna at the two ends of the straight hollow metal pipe respectively, that is, the antenna receiving and transmitting distance is always equal to the distance between the two ends of the pipe; adjusting the height control bracket to change the coupling distance, setting a measurement point every X (the value of this measurement scene is 1 cm); performing X at each measurement point 1(Generally, the value is 9) measurements and the average path loss is calculated.

[0029] In step 2, the measurement data includes the coupling distance , and the path loss value of each measurement point.

[0030] In step 3, the surface wave path loss attenuation value About coupling distance The parameter function model is:

[0031] , (1)

[0032] Among them, A, B, and n are the parameters to be fitted;

[0033] The path loss attenuation value is obtained by parameter fitting using the nonlinear least squares method. About coupling distance The function is:

[0034] , (2)

[0035] The residual sum of squares SSE is used to evaluate the values ​​of the fitting parameters A, B, and n in formula (2). The closer the residual sum of squares SSE is to 0, the smaller the random error component of the model is and the better the fitting effect is. The actual measured value and predicted value of the function are set as and , the calculation formula of the residual sum of squares SSE is:

[0036] , (3)

[0037] Will The ith actual measurement value of ,get:

[0038] , (4)

[0039] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitting parameters are meaningful. Otherwise, refit. N is the number of measured values. for The i-th predicted value of .

[0040] In step 4, the path loss index About coupling distance The parameter function model is:

[0041] , (5)

[0042] Among them, a, b, and c are the parameters to be fitted;

[0043] The path loss index is obtained by parameter fitting using the nonlinear least squares method. About coupling distance The function is:

[0044] , (6)

[0045] The residual sum of squares SSE is used to evaluate the values ​​of the fitting parameters a, b, and c in formula (6). The ith actual measurement value of ,get:

[0046] , (7)

[0047] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed. for The i-th predicted value of .

[0048] In step 5, the channel path loss model of wireless communication combined with surface waves in the straight metal pipe excitation surface wave scenario is:

[0049] , (8)

[0050] , (9)

[0051] Where d is the distance between the antenna transmitting and receiving ends, is the angle between the antenna transmitting and receiving ends, , and They are d, and The initial value of For The path loss value at For the initial value The path loss value at For The path loss exponent at For The path loss attenuation value at Shadow fading, shadow fading It has a mean of zero and a standard deviation of Normal distribution of and Represents the distribution function The variance and mean of the signal, p is the coupling distance The transmission-receive power ratio at , exp is the natural exponential function;

[0052] In the scenario of surface waves excited by a straight metal pipe, the distance between the antenna and the receiver is fixed to the distance between the two ends of the metal pipe. The antenna and the receiver are facing each other. Therefore, d is a constant, which is taken as the distance between the antenna and the receiver. ; is a constant, taking the value of 0°, so as to construct the parameter-containing model of the channel path loss function of wireless communication combined with surface waves:

[0053] , (10)

[0054] Among them, C is the parameter to be fitted, and the initial value of the coupling distance is 0.1cm; The coupling distance for the straight metal pipe in the scenario of exciting surface waves The path loss value at The coupling distance for the straight metal pipe in the scenario of exciting surface waves Take the path loss value at the initial value of 0.1cm;

[0055] By using the nonlinear least squares method to fit the parameters, the channel path loss model of wireless communication combined with surface waves in the scenario of surface waves excited by straight metal pipes is obtained as follows:

[0056] , (11)

[0057] The residual sum of squares SSE is used to evaluate the value of the fitting parameter C in step 5. The ith actual measurement value of ,get:

[0058] , (12)

[0059] in, for The residual square sum of the straight metal pipe excitation surface wave scene is set to 10. When the threshold is less than 10, the fitting effect is better and the fitted parameters are meaningful. Otherwise, refitting is performed. for The i-th predicted value of .

[0060] In step 6, the orthogonal hollow metal pipe excited surface wave system model includes two planar magnetic dipole antennas, an orthogonal hollow metal pipe and a pair of coupling devices with adjustable distance;

[0061] The setting of the measurement scene includes: fixing the transmitting end and the receiving end of the antenna at the two ends of the orthogonal hollow metal pipe respectively, the transmitting and receiving antennas are oriented orthogonally, adjusting the height control bracket to change the coupling distance, and setting a measurement point every X; performing X at each measurement point 1 Measure and calculate the average path loss;

[0062] In step 7, the measurement data includes the coupling distance and the path loss value of each measurement point.

[0063] In step 8, the path loss attenuation value About coupling distance The parameter function model is:

[0064] , (13)

[0065] Among them, D, E, and m are the parameters to be fitted;

[0066] The path loss attenuation value is obtained by parameter fitting using the nonlinear least squares method. About coupling distance The function is:

[0067] , (14)

[0068] The residual sum of squares SSE is used to evaluate the values ​​of the fitting parameters D, E, and m in step 8. The ith actual measurement value of ,get:

[0069] , (15)

[0070] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed; for The i-th predicted value of ;

[0071] In step 9, the path loss index About coupling distance The parameter function model of is:

[0072] , (16)

[0073] Among them, e, f, and g are the parameters to be fitted;

[0074] The path loss attenuation value is obtained by parameter fitting using the nonlinear least squares method. About coupling distance The function is:

[0075] , (17)

[0076] The residual sum of squares SSE is used to evaluate the values ​​of the fitting parameters e, f, and g in step 9. The ith actual measurement value of ,get:

[0077] , (18)

[0078] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed. for The i-th predicted value of ;

[0079] In step 10, in the scenario of orthogonal metal pipes exciting surface waves, the distance between the antenna transceiver is fixed to the distance between the two ends of the metal pipe, and the antenna transceiver is oriented orthogonally, that is, d. is a constant, and , , the parameterized model of the channel path loss function of wireless communication combined with surface waves is constructed as follows:

[0080] , (19)

[0081] in, The coupling distance for the orthogonal metal pipe excitation surface wave scenario The path loss value at The coupling distance for the orthogonal metal pipe excitation surface wave scenario Take the path loss value at the initial value of 0.1cm, and F is the parameter to be fitted;

[0082] By using the nonlinear least squares method to fit the parameters, the channel path loss model of wireless communication combined with surface waves in the scenario of orthogonal metal pipes exciting surface waves is obtained as follows:

[0083] , (20)

[0084] The residual sum of squares SSE is used to evaluate the value of the fitting parameter F in step 10. The ith actual measurement value of ,get:

[0085] ,(twenty one)

[0086] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed. for The i-th predicted value of .

[0087] In step 11, the channel model obtained in the straight metal tube excitation surface wave scenario, the channel model obtained in the orthogonal metal tube excitation surface wave scenario and the free space transmission channel model are compared, and it is found that both the straight metal tube excitation surface wave and the orthogonal metal tube excitation surface wave have channel transmission characteristics that are significantly better than free space transmission. However, compared with the straight metal tube excitation surface wave, the channel transmission characteristics of the orthogonal metal tube excitation surface wave are worse. The channel transmission characteristics of the orthogonal metal tube excitation surface wave are compensated and optimized by introducing copper wire.

[0088] In step 12, the orthogonal metal pipe excited surface wave system model with copper conductor compensation includes two planar magnetic dipole antennas, orthogonal hollow metal pipes, copper conductor loops and a pair of coupling devices with adjustable distances as in step 1;

[0089] In step 12, the setting of the measurement scene includes: fixing the transmitting end and the receiving end of the antenna at the two ends of the orthogonal hollow metal pipe respectively, stretching the copper wire to be straight, fixing the two ends of the copper wire to the transmitting end and the receiving end of the antenna respectively, adjusting the height control bracket to change the coupling distance, setting a measurement point every X; performing X at each measurement point 1 Measure and calculate the average path loss;

[0090] In step 13, the measurement data includes coupling distance , and the path loss value of each measurement point.

[0091] In step 14, the path loss attenuation value About coupling distance The parameter function model is:

[0092] ,(twenty two)

[0093] Among them, G, H, l is the parameter to be fitted;

[0094] The path loss attenuation value is obtained by parameter fitting using the nonlinear least squares method. About coupling distance The function is:

[0095] ,(twenty three)

[0096] The residual sum of squares SSE is used to calculate the fitting parameters G, H, l The value of The ith actual measurement value of ,get:

[0097] ,(twenty four)

[0098] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed. for The i-th predicted value of ;

[0099] In step 15, the path loss index About coupling distance The parameter function model of is:

[0100] , (25)

[0101] Among them, h, j, and k are the parameters to be fitted;

[0102] The path loss attenuation value is obtained by parameter fitting using the nonlinear least squares method. About coupling distance The function is:

[0103] , (26)

[0104] The residual sum of squares SSE is used to evaluate the fitting parameters h, j, and k in step 15. The ith actual measurement value of ,get:

[0105] , (27)

[0106] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed. for The i-th predicted value of ;

[0107] In step 16, in the scenario of orthogonal metal pipes exciting surface waves with copper wires as compensation, the parameter-containing model of the channel path loss function of wireless communication combined with surface waves is affected by both orthogonal hollow metal pipes and copper wires, and the following initial parameter-containing model is established:

[0108] , (28)

[0109] in, Coupling distance for surface waves excited by orthogonal metal pipes with copper conductors as compensation The path loss value at Coupling distance for surface waves excited by orthogonal metal pipes with copper conductors as compensation Take the path loss value at the initial value of 0.1cm, K, M, T are the parameters to be fitted;

[0110] By performing parameter fitting using the nonlinear least squares method, it is concluded that the channel path loss model of wireless communication combined with surface waves in the scenario of orthogonal metal pipes exciting surface waves with the introduction of copper wires as compensation is:

[0111] , (29)

[0112] The residual sum of squares SSE is used to evaluate the fitting parameters K, M, and T in step 16. The ith actual measurement value of ,get:

[0113] , (30)

[0114] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed. for The i-th predicted value of .

[0115] The present invention provides a method for measuring indoor wireless channels and modeling and optimizing path loss based on metal pipe surface wave excitation in an industrial Internet of Things scenario. First, the coupling effect between metal conductors and media is used to excite surface waves through metal pipes commonly found in industrial Internet of Things environments, thereby generating a surface wave channel that effectively reduces path loss. Then, the communication channels generated by the surface waves excited by metal pipes of different structures are measured and modeled. For orthogonal pipe structures with poor channel conditions, wires are introduced as compensation to optimize channel characteristics.

[0116] Beneficial effects: The present invention combines the wired channel with the wireless channel by introducing the metal pipe into the surface wave. Tests have confirmed that the surface waves excited by the straight metal pipe and the orthogonal metal pipe can effectively reduce the path loss during the signal transmission process in the indoor environment of the industrial Internet of Things, and the introduction of the wire as compensation optimizes the transmission performance in the case of the orthogonal metal pipe, thereby providing help for the design of the wireless system and the optimization of the system performance in the industrial Internet of Things environment with metal pipes. In addition, the method proposed by the present invention for measuring and modeling three different scenarios based on metal pipes is an improvement on the traditional indoor wireless channel measurement scheme. The previous measurement experiments measured and modeled the wireless channel propagating in free space between the transceiver and the optimized channel after artificial intervention and adding conductors. The present invention takes into account the excitation effect of the metal pipe on the surface wave in the industrial Internet of Things scenario, introduces the influencing factors brought by the metal pipe exciting the surface wave, improves the measurement scenario, reduces the cost required for channel measurement, and improves the effectiveness and reliability of the wireless communication system in the industrial Internet of Things environment with metal pipes. BRIEF DESCRIPTION OF THE DRAWINGS

[0117] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0118] Figure 1 Diagram of the experimental scene for indoor channel measurement with surface wave excitation introduced into a straight metal pipe.

[0119] Figure 2 Diagram of the experimental scenario for indoor channel measurement with orthogonal metal pipe surface wave excitation.

[0120] Figure 3 Diagram of the experimental scenario for indoor channel measurement with orthogonal metal pipe surface wave excitation and copper wire as compensation. DETAILED DESCRIPTION

[0121] The present invention specifically provides a method for measuring and modeling a metal pipe excited surface wave transmission channel, comprising the following steps:

[0122] Step 1, simulating a real industrial Internet of Things scenario, establishing a straight hollow metal pipe excited surface wave system model, setting a measurement scenario, and measuring the channel transmission characteristics of the system model;

[0123] Step 2, obtaining the data measured in step 1, and calculating the average path loss value of each measurement point;

[0124] Step 3: Construct the surface wave path loss attenuation value caused by the coupling distance in the scenario of surface waves excited by a straight metal pipe About coupling distance The parameter function model uses nonlinear least squares method to fit the parameters, and we get About coupling distance function and tested it by the residual sum of squares SSE;

[0125] Step 4: Based on the path loss index values ​​and coupling distances at different coupling distances, the path loss index based on different coupling distances in the straight metal pipe excitation surface wave scenario is constructed. About coupling distance The parameter function model uses nonlinear least squares method to fit the parameters, and we get About coupling distance function, and tested by the residual sum of squares SSE;

[0126] Step 5, construct a channel path loss model of wireless communication combined with surface waves in a straight metal pipe excitation surface wave scenario, use nonlinear least squares method to fit parameters, and perform data verification;

[0127] Step 6, simulating a real industrial Internet of Things scenario, constructing an orthogonal hollow metal pipe excited surface wave system model, setting a measurement scenario, and measuring the channel transmission characteristics of the system model;

[0128] Step 7, obtaining the data measured in step 6, and calculating the average path loss value of each measurement point;

[0129] Step 8: Construct the surface wave path loss attenuation value caused by the coupling distance in the orthogonal metal pipe excitation surface wave scenario About coupling distance The parameter function model uses nonlinear least squares method to fit the parameters, and we get About coupling distance function and perform data verification;

[0130] Step 9: Based on the path loss index values ​​and coupling distances at different coupling distances, the path loss index based on different coupling distances in the orthogonal metal pipe excitation surface wave scenario is constructed. About coupling distance The parameter function model uses nonlinear least squares method to fit the parameters, and we get About coupling distance function and perform data verification;

[0131] Step 10, constructing a channel path loss model of wireless communication combined with surface waves in a scenario of orthogonal metal pipes exciting surface waves, fitting parameters using a nonlinear least squares method, and performing data verification;

[0132] Step 11, comparing the channel model obtained in step 1 and step 10 with the free space transmission channel model, and designing a scheme to optimize the channel transmission characteristics of surface waves excited by orthogonal metal pipes using copper wires;

[0133] Step 12, constructing an orthogonal metal pipe excited surface wave system model introducing copper wire compensation according to the scheme designed in step 11, setting a measurement scene, and measuring the channel transmission characteristics of the system model;

[0134] Step 13, obtaining the data measured in step 12, and calculating the average path loss value of each measurement point;

[0135] Step 14: construct the surface wave path loss attenuation value caused by the coupling distance in the scenario of orthogonal metal pipe excitation surface wave with the copper wire introduced as compensation About coupling distance The parameter function model is fitted using the nonlinear least squares method, and the results are About coupling distance function and perform data verification;

[0136] Step 15, based on the path loss index values ​​and coupling distances at different coupling distances, construct a path loss index based on different coupling distances in a scenario where an orthogonal metal pipe excites a surface wave and introduces a copper conductor as compensation. About coupling distance The parameter function model uses nonlinear least squares method to fit the parameters, and we get About coupling distance function and perform data verification;

[0137] Step 16, construct a channel path loss model of wireless communication combined with surface waves in a scenario where copper wires are introduced as compensation for orthogonal metal pipe-excited surface waves, use nonlinear least squares method to fit parameters, and perform data verification.

[0138] In step 1, the straight hollow metal pipe excitation surface wave system model includes two planar magnetic dipole antennas, a straight hollow metal pipe and a pair of coupling devices with adjustable distance;

[0139] The two planar magnetic dipole antennas are used for transmitting and receiving signals respectively. The planar magnetic dipole antenna is an antenna with a transmitting angle and a receiving angle both greater than 30 degrees. It is a wide beam antenna, and its main feature is a wider main lobe and smaller side lobes.

[0140] The distance-adjustable coupling device is used to control the distance between the metal pipe and the antenna;

[0141] The hollow metal pipe serves as a medium for signal transmission and connects two planar magnetic dipole antennas;

[0142] The coupling device adopts an adjustable structure, including two layers of PVC boards and a height control bracket. The antenna is located between the two layers of PVC boards and is close to the lower PVC board. The four corners of the upper and lower PVC boards are fixed with screws. The distance between the hollow metal pipe and the antenna can be changed by adjusting the height control bracket. The distance between the hollow metal pipe and the antenna is the coupling distance.

[0143] Mechanism of signal transmission: In the wireless channel measurement system of the present invention, a part of the signal is still transmitted through the wireless channel, but most of the signal is transmitted to the receiving antenna along the surface of the hollow metal pipe in the form of surface waves.

[0144] The setting of the measurement scene includes: fixing the transmitting end and the receiving end of the antenna at the two ends of the straight hollow metal pipe respectively, that is, the antenna receiving and transmitting distance is always equal to the distance between the two ends of the pipe; adjusting the height control bracket to change the coupling distance, setting a measurement point every X (the value of this measurement scene is 1 cm); performing X at each measurement point 1 (Generally, the value is 9) measurements and the average path loss is calculated.

[0145] In step 2, the measurement data includes the coupling distance , and the path loss value of each measurement point.

[0146] In step 3, the surface wave path loss attenuation value About coupling distance The parameter function model is:

[0147] , (1)

[0148] Among them, A, B, and n are the parameters to be fitted;

[0149] The path loss attenuation value is obtained by parameter fitting using the nonlinear least squares method. About coupling distance The function is:

[0150] , (2)

[0151] The residual sum of squares SSE is used to evaluate the values ​​of the fitting parameters A, B, and n in formula (2). The closer the residual sum of squares SSE is to 0, the smaller the random error component of the model is and the better the fitting effect is. The actual measured value and predicted value of the function are set as and , the calculation formula of the residual sum of squares SSE is:

[0152] , (3)

[0153] Will The ith actual measurement value of ,get:

[0154] , (4)

[0155] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitting parameters are meaningful. Otherwise, refit. N is the number of measured values. for The i-th predicted value of .

[0156] In step 4, the path loss index About coupling distance The parameter function model is:

[0157] , (5)

[0158] Among them, a, b, and c are the parameters to be fitted;

[0159] The path loss index is obtained by parameter fitting using the nonlinear least squares method. About coupling distance The function is:

[0160] , (6)

[0161] The residual sum of squares SSE is used to evaluate the values ​​of the fitting parameters a, b, and c in formula (6). The ith actual measurement value of ,get:

[0162] , (7)

[0163] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed. for The i-th predicted value of .

[0164] In step 5, the channel path loss model of wireless communication combined with surface waves in the straight metal pipe excitation surface wave scenario is:

[0165] , (8)

[0166] , (9)

[0167] Where d is the distance between the antenna transmitting and receiving ends, is the angle between the antenna transmitting and receiving ends, , and They are d, and The initial value of For The path loss value at For the initial value The path loss value at For The path loss exponent at For The path loss attenuation value at Shadow fading, shadow fading It has a mean of zero and a standard deviation of Normal distribution of and Represents the distribution function The variance and mean of the signal, p is the coupling distance The transmission-receive power ratio at , exp is the natural exponential function;

[0168] In the scenario of surface waves excited by a straight metal pipe, the distance between the antenna and the receiver is fixed to the distance between the two ends of the metal pipe. The antenna and the receiver are facing each other. Therefore, d is a constant, which is taken as the distance between the antenna and the receiver. ; is a constant, taking the value of 0°, so as to construct the parameter-containing model of the channel path loss function of wireless communication combined with surface waves:

[0169] , (10)

[0170] Among them, C is the parameter to be fitted, and the initial value of the coupling distance is 0.1cm; The coupling distance for the straight metal pipe in the scenario of exciting surface waves The path loss value at The coupling distance for the straight metal pipe in the scenario of exciting surface waves Take the path loss value at the initial value of 0.1cm;

[0171] By using the nonlinear least squares method to fit the parameters, the channel path loss model of wireless communication combined with surface waves in the scenario of surface waves excited by straight metal pipes is obtained as follows:

[0172] , (11)

[0173] The residual sum of squares SSE is used to evaluate the value of the fitting parameter C in step 5. The ith actual measurement value of ,get:

[0174] , (12)

[0175] in, for The residual square sum of the straight metal pipe excitation surface wave scene is set to 10. When the threshold is less than 10, the fitting effect is better and the fitted parameters are meaningful. Otherwise, refitting is performed. for The i-th predicted value of .

[0176] In step 6, the orthogonal hollow metal pipe excited surface wave system model includes two planar magnetic dipole antennas, an orthogonal hollow metal pipe and a pair of coupling devices with adjustable distance;

[0177] The setting of the measurement scene includes: fixing the transmitting end and the receiving end of the antenna at the two ends of the orthogonal hollow metal pipe respectively, the transmitting and receiving antennas are oriented orthogonally, adjusting the height control bracket to change the coupling distance, and setting a measurement point every X; performing X at each measurement point 1 Measure and calculate the average path loss;

[0178] In step 7, the measurement data includes the coupling distance and the path loss value of each measurement point.

[0179] In step 8, the path loss attenuation value About coupling distance The parameter function model is:

[0180] , (13)

[0181] Among them, D, E, and m are the parameters to be fitted;

[0182] The path loss attenuation value is obtained by parameter fitting using the nonlinear least squares method. About coupling distance The function is:

[0183] , (14)

[0184] The residual sum of squares SSE is used to evaluate the values ​​of the fitting parameters D, E, and m in step 8. The ith actual measurement value of ,get:

[0185] , (15)

[0186] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed; for The i-th predicted value of ;

[0187] In step 9, the path loss index About coupling distance The parameter function model of is:

[0188] , (16)

[0189] Among them, e, f, and g are the parameters to be fitted;

[0190] The path loss attenuation value is obtained by parameter fitting using the nonlinear least squares method. About coupling distance The function is:

[0191] , (17)

[0192] The residual sum of squares SSE is used to evaluate the values ​​of the fitting parameters e, f, and g in step 9. The ith actual measurement value of ,get:

[0193] , (18)

[0194] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed. for The i-th predicted value of ;

[0195] In step 10, in the scenario of orthogonal metal pipes exciting surface waves, the distance between the antenna transceiver is fixed to the distance between the two ends of the metal pipe, and the antenna transceiver is oriented orthogonally, that is, d. is a constant, and , , the parameterized model of the channel path loss function of wireless communication combined with surface waves is constructed as follows:

[0196] , (19)

[0197] in, The coupling distance for the orthogonal metal pipe excitation surface wave scenario The path loss value at The coupling distance for the orthogonal metal pipe excitation surface wave scenario Take the path loss value at the initial value of 0.1cm, and F is the parameter to be fitted;

[0198] By using the nonlinear least squares method to fit the parameters, the channel path loss model of wireless communication combined with surface waves in the scenario of orthogonal metal pipes exciting surface waves is obtained as follows:

[0199] , (20)

[0200] The residual sum of squares SSE is used to evaluate the value of the fitting parameter F in step 10. The ith actual measurement value of ,get:

[0201] ,(twenty one)

[0202] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed. for The i-th predicted value of .

[0203] In step 11, the channel model obtained in the straight metal tube excitation surface wave scenario, the channel model obtained in the orthogonal metal tube excitation surface wave scenario and the free space transmission channel model are compared, and it is found that both the straight metal tube excitation surface wave and the orthogonal metal tube excitation surface wave have channel transmission characteristics that are significantly better than free space transmission. However, compared with the straight metal tube excitation surface wave, the channel transmission characteristics of the orthogonal metal tube excitation surface wave are worse. The channel transmission characteristics of the orthogonal metal tube excitation surface wave are compensated and optimized by introducing copper wire.

[0204] In step 12, the orthogonal metal pipe excited surface wave system model with copper conductor compensation includes two planar magnetic dipole antennas, orthogonal hollow metal pipes, copper conductor loops and a pair of coupling devices with adjustable distances as in step 1;

[0205] In step 12, the setting of the measurement scene includes: fixing the transmitting end and the receiving end of the antenna at the two ends of the orthogonal hollow metal pipe respectively, stretching the copper wire to be straight, fixing the two ends of the copper wire to the transmitting end and the receiving end of the antenna respectively, adjusting the height control bracket to change the coupling distance, setting a measurement point every X; performing X at each measurement point 1Measure and calculate the average path loss;

[0206] In step 13, the measurement data includes coupling distance , and the path loss value of each measurement point.

[0207] In step 14, the path loss attenuation value About coupling distance The parameter function model is:

[0208] ,(twenty two)

[0209] Among them, G, H, l is the parameter to be fitted;

[0210] The path loss attenuation value is obtained by parameter fitting using the nonlinear least squares method. About coupling distance The function is:

[0211] ,(twenty three)

[0212] The residual sum of squares SSE is used to calculate the fitting parameters G, H, l The value of The ith actual measurement value of ,get:

[0213] ,(twenty four)

[0214] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed. for The i-th predicted value of ;

[0215] In step 15, the path loss index About coupling distance The parameter function model of is:

[0216] , (25)

[0217] Among them, h, j, and k are the parameters to be fitted;

[0218] The path loss attenuation value is obtained by parameter fitting using the nonlinear least squares method. About coupling distance The function is:

[0219] , (26)

[0220] The residual sum of squares SSE is used to evaluate the fitting parameters h, j, and k in step 15. The ith actual measurement value of ,get:

[0221] , (27)

[0222] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed. for The i-th predicted value of ;

[0223] In step 16, in the scenario of orthogonal metal pipes exciting surface waves with copper wires as compensation, the parameter-containing model of the channel path loss function of wireless communication combined with surface waves is affected by both orthogonal hollow metal pipes and copper wires, and the following initial parameter-containing model is established:

[0224] , (28)

[0225] in, Coupling distance for surface waves excited by orthogonal metal pipes with copper conductors as compensation The path loss value at Coupling distance for surface waves excited by orthogonal metal pipes with copper conductors as compensation Take the path loss value at the initial value of 0.1cm, K, M, T are the parameters to be fitted;

[0226] By performing parameter fitting using the nonlinear least squares method, it is concluded that the channel path loss model of wireless communication combined with surface waves in the scenario of orthogonal metal pipes exciting surface waves with the introduction of copper wires as compensation is:

[0227] , (29)

[0228] The residual sum of squares SSE is used to evaluate the fitting parameters K, M, and T in step 16. The ith actual measurement value of ,get:

[0229] , (30)

[0230] in, for The residual sum of squares, in this scenario, is set to 10. When it is less than 10, the fitting effect is good and the fitted parameters are meaningful, otherwise refitting is performed. for The i-th predicted value of .

[0231] The present invention is applicable to wireless communication scenarios where metal pipes exist in industrial Internet of Things scenarios. When dealing with the problems of the prior art in the corresponding scenarios, the metal pipes can be used to excite surface waves to optimize the communication performance of the wireless channel.

[0232] In a specific embodiment of the present invention, when wireless communication is performed in a factory, for a metal pipe with a distance of 3 m between the two ends, when the metal pipe is a straight pipe, the experimental scenario is as follows: Figure 1 When the coupling distance is the initial coupling distance of 0.1cm, the channel path loss fluctuates around 35dB, while the path loss fluctuates around 60dB in free space propagation. In comparison, the channel path loss is significantly reduced compared to free space propagation. As the coupling distance increases, the path loss continues to increase. When the coupling distance is 4.1cm, the path loss fluctuates around 40dB. When the metal pipe is an orthogonal pipe, the experimental scenario is as follows: Figure 2 When the coupling distance is the initial coupling distance of 0.1cm, the channel path loss fluctuates around 50dB. In comparison, the channel path loss is reduced compared to free space propagation, but the optimization effect is poorer than that of a straight pipe. Therefore, the present invention compensates for the channel path loss in the orthogonal case by connecting the two ends of the metal pipe with copper wire. The experimental scenario is as follows Figure 3 After measurement, the channel path loss of the orthogonal pipe with copper wire as compensation fluctuates around 35dB when the coupling distance is the initial coupling distance of 0.1cm, which is significantly improved compared with the channel path loss in the orthogonal scenario. Moreover, when the coupling distance is 4.1cm, the path loss is less than 40dB, which is less affected by the coupling distance and is better than the straight metal pipe case.

[0233] The present invention provides a method for measuring and modeling a metal pipe excited surface wave transmission channel. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A method for measuring and modeling a metal pipe excited surface wave transmission channel, characterized in that: The following steps are involved: Step 1, simulating a real industrial Internet of Things scenario, establishing a straight hollow metal pipe excited surface wave system model, setting a measurement scenario, and measuring the channel transmission characteristics of the system model; Step 2, obtaining the data measured in step 1, and calculating the average path loss value of each measurement point; Step 3: Construct the surface wave path loss attenuation value S(d) caused by the coupling distance in the scenario of surface wave excited by a straight metal pipe. c ) about the coupling distance d c The parameter function model is fitted using the nonlinear least squares method to obtain S(d c ) about the coupling distance d c function and tested it by the residual sum of squares SSE; Step 4: Based on the path loss index values ​​and coupling distances at different coupling distances, the path loss index N(d c ) About the coupling distance d c The parameter function model is fitted using the nonlinear least squares method to obtain N(d c ) About the coupling distance d c function, and tested by the residual sum of squares SSE; Step 5, construct a channel path loss model of wireless communication combined with surface waves in a straight metal pipe excitation surface wave scenario, use nonlinear least squares method to fit parameters, and perform data verification; Step 6, simulating a real industrial Internet of Things scenario, constructing an orthogonal hollow metal pipe excited surface wave system model, setting a measurement scenario, and measuring the channel transmission characteristics of the system model; Step 7, obtaining the data measured in step 6, and calculating the average path loss value of each measurement point; Step 8: Construct the surface wave path loss attenuation value SZ(d c ) about the coupling distance d c The parameter function model is fitted using the nonlinear least squares method to obtain SZ(d c ) about the coupling distance d c function and perform data verification; Step 9: Based on the path loss index values ​​and coupling distances at different coupling distances, a path loss index NZ(d c ) About the coupling distance d c The parameter function model is fitted using the nonlinear least squares method to obtain NZ(d c ) About the coupling distance d c function and perform data verification; Step 10, constructing a channel path loss model of wireless communication combined with surface waves in a scenario of orthogonal metal pipes exciting surface waves, fitting parameters using a nonlinear least squares method, and performing data verification; Step 11, comparing the channel model obtained in step 1 and step 10 with the free space transmission channel model, and designing a scheme to optimize the channel transmission characteristics of surface waves excited by orthogonal metal pipes using copper wires; Step 12, constructing an orthogonal metal pipe excited surface wave system model introducing copper wire compensation according to the scheme designed in step 11, setting a measurement scene, and measuring the channel transmission characteristics of the system model; Step 13, obtaining the data measured in step 12, and calculating the average path loss value of each measurement point; Step 14, construct the surface wave path loss attenuation value SY (d c ) about the coupling distance d c The parameter function model is fitted using the nonlinear least squares method to obtain SY(d c ) About the coupling distance d c function and perform data verification; Step 15, based on the path loss index values ​​and coupling distances at different coupling distances, construct the path loss index NY (d c ) About the coupling distance d c The parameter function model is fitted using the nonlinear least squares method to obtain NY(d c ) About the coupling distance d c function and perform data verification; Step 16, constructing a channel path loss model of wireless communication combined with surface waves in a scenario where copper wires are introduced as compensation for surface waves excited by orthogonal metal pipes, fitting parameters using a nonlinear least squares method, and performing data verification; In step 11, the channel model obtained in the straight metal tube excitation surface wave scenario, the channel model obtained in the orthogonal metal tube excitation surface wave scenario and the free space transmission channel model are compared, and the channel transmission characteristics of the orthogonal metal tube excitation surface wave are compensated and optimized by introducing copper wires; In step 12, the orthogonal metal pipe excited surface wave system model with copper conductor compensation includes two planar magnetic dipole antennas, orthogonal hollow metal pipes, copper conductor loops and a pair of coupling devices with adjustable distances as in step 1; In step 12, setting the measurement scene includes: fixing the transmitting end and the receiving end of the antenna at the two ends of the orthogonal hollow metal pipe respectively, stretching the copper wire to be straight, fixing the two ends of the copper wire to the transmitting end and the receiving end of the antenna respectively, adjusting the height control bracket to change the coupling distance, and setting a measurement point every X; at each measurement point, performing X1 measurements, and calculating the average path loss; In step 13, the measurement data includes the coupling distance d c , and the path loss value of each measurement point; In step 14, the path loss attenuation value SY(d c ) about the coupling distance d c The parameter function model is: SY (d c )=G log l (d c )+H (22) Among them, G, H, and l are the parameters to be fitted; The path loss attenuation value SY(d c ) about the coupling distance d c The function is: AND(d c )=-0.2906log 10 (d) c )+28.69 (23) The residual sum of squares SSE is used to evaluate the values ​​of the fitting parameters G, H, and l in step 14, and SY(d c ) is set as SY i0 (d c ),get: Among them, SSE[SY(d c )] is the function SY(d c ) of the residual sum of squares, SY i0 (d c ) is the actual measured value of the ith value, SY i (d c ) is the function SY(d c )’s ith predicted value; In step 15, the path loss index NY(d c ) About the coupling distance d c The parameter function model of is: NY(d c )=hd c 2 +jd c +k (25) Among them, h, j, k are the parameters to be fitted; The path loss attenuation value NY(d c ) About the coupling distance d c The function is: NY(d c )=24.28d c 2 -16.45d c +0.4299 (26) The residual sum of squares SSE is used to evaluate the fitting parameters h, j, and k in step 15, and NY(d c ) is set to NY i0 (d c ),get: Among them, SSE[NY(d c )] is the function NY(d c ), NY i0 (d c ) is the actual measured value of the ith i (d c ) is the function NY(d c )’s ith predicted value; In step 16, in the scenario of orthogonal metal pipes exciting surface waves with copper wires as compensation, the parameter-containing model of the channel path loss function of wireless communication combined with surface waves is affected by both orthogonal hollow metal pipes and copper wires, and the following initial parameter-containing model is established: PL3(d c )=PL3(d c0 )+Kd c 2 +Md c +SY(d c )+T (28) Among them, PL3(d c ) is the case of surface waves excited by orthogonal metal pipes with copper wires as compensation. c The path loss value at PL3(d c0 ) is the coupling distance d in the scenario of surface waves excited by orthogonal metal pipes with copper wires as compensation c Take the path loss value at the initial value of 0.1cm, K, M, T are the parameters to be fitted; By performing parameter fitting using the nonlinear least squares method, it is concluded that the channel path loss model of wireless communication combined with surface waves in the scenario of orthogonal metal pipes exciting surface waves with the introduction of copper wires as compensation is: PL3(d c )=PL3(d c )+11.41d c 2 -7.73d c -0.2906log 10 (d c )+31.89 (29) The residual sum of squares SSE is used to evaluate the fitting parameters K, M, and T in step 16, and PL3(d c ) is set as PL i03 (d c ),get: Among them, SSE[PL3(d c )] is the function PL3(d c ), PL i03 (d c ) is the actual measured value of the ith value, PL i3 (d c ) is the function PL3(d c )’s ith predicted value.

2. The method according to claim 1, characterized in that: In step 1, the straight hollow metal pipe excitation surface wave system model includes two planar magnetic dipole antennas, a straight hollow metal pipe and a pair of coupling devices with adjustable distance; The two planar magnetic dipole antennas are used for transmitting signals and receiving signals respectively. The planar magnetic dipole antenna is an antenna with a transmitting angle and a receiving angle both greater than 30 degrees, and is a wide beam antenna. The distance-adjustable coupling device is used to control the distance between the metal pipe and the antenna; The hollow metal pipe serves as a medium for signal transmission and connects two planar magnetic dipole antennas; The coupling device adopts an adjustable structure, including two layers of PVC boards and a height control bracket. The antenna is located between the two layers of PVC boards and is close to the lower PVC board. The four corners of the upper and lower PVC boards are fixed with screws. The distance between the hollow metal pipe and the antenna can be changed by adjusting the height control bracket. The distance between the hollow metal pipe and the antenna is the coupling distance. The setting of the measurement scenario includes: fixing the transmitting end and the receiving end of the antenna at the two ends of a straight hollow metal pipe respectively, that is, the antenna receiving and transmitting distance is always equal to the distance between the two ends of the pipe; adjusting the height control bracket to change the coupling distance, and setting a measurement point every X; at each measurement point, performing X1 measurements, and calculating the average path loss.

3. The method according to claim 2, characterized in that In step 2, the measured data includes the coupling distance d c , and the path loss value of each measurement point.

4. The method according to claim 3, characterized in that In step 3, the surface wave path loss attenuation value S(d c ) about the coupling distance d c The parameter function model is: S(d c )=Alog n (d c )+B (1) Among them, A, B, and n are the parameters to be fitted; The path loss attenuation value S(d c ) about the coupling distance d c The function is: S(d c )=7.672log 10 (d c )+46.17 (2) The residual sum of squares SSE is used to evaluate the values ​​of the fitting parameters A, B, and n in formula (2). The actual measured value and predicted value of the function are set to y(d c ) and f(d c ), the calculation formula of the residual sum of squares SSE is: S(d c ) is set as S i0 (d c ),get: Among them, SSE[S(d c )] is the function S(d c ), N is the number of measured values, S i0 (d c ) is the actual measured value of the ith value, S i (d c ) is the function S(d c )’s ith predicted value.

5. The method according to claim 4, characterized in that In step 4, the path loss index N(d c ) About the coupling distance d c The parameter function model is: N(d c )=ad c 2 +bd c +c (5) Among them, a, b, and c are the parameters to be fitted; The path loss index N(d c ) About the coupling distance d c The function is: N(d c )=-3.02d c 2 +11.9d c +0.309 (6) The residual sum of squares SSE is used to evaluate the values ​​of the fitting parameters a, b, and c in formula (6), and N(d c ) is set as N i0 (d c ),get: Among them, SSE[N(d c )] is the function N(d c ), N i0 (d c ) is the actual measured value of the ith i (d c ) is the function N(d c )’s ith predicted value.

6. The method according to claim 5, characterized in that In step 5, the channel path loss model of wireless communication combined with surface waves in the straight metal pipe excitation surface wave scenario is: Where d is the distance between the antenna and the receiver, θ is the angle between the antenna and the receiver, d0, d c0 , θ0 are d, d c , the initial value of θ, PL(d, d c ,θ) is the c , θ), PL(d0, d c0 ,θ0) is the initial value (d0, d c0 , θ0) path loss value, NL(d c ,θ) is the c , θ) at the path loss index, SW(d c ,θ) is the c , the path loss attenuation value at θ), Shadow fading, shadow fading It follows a normal distribution with mean zero and standard deviation σ; σ and μ p They represent the distribution functions The variance and mean of the signal at the coupling distance d c The transmission-receive power ratio at , exp is the natural exponential function; In the scenario of surface waves excited by a straight metal pipe, the distance between the antenna and the receiving end is fixed to the distance between the two ends of the metal pipe, and the antenna and the receiving end are facing each other. Therefore, d is a constant, which is taken as the distance between the antenna and the receiving end d0; θ is a constant, which is taken as 0°, so the parameter-containing model of the channel path loss function of wireless communication combined with surface waves is constructed as follows: PL1(d c )=PL1(d c0 )+S(d c )+C (10) Among them, C is the parameter to be fitted, and the initial value of the coupling distance d c0 0.1cm; PL1(d c ) is the coupling distance d in the scenario of surface waves excited by a straight metal pipe c The path loss value at PL1(d c0 ) is the coupling distance d in the scenario of surface waves excited by a straight metal pipe c Take the path loss value at the initial value of 0.1cm; By using the nonlinear least squares method to fit the parameters, the channel path loss model of wireless communication combined with surface waves in the scenario of surface waves excited by straight metal pipes is obtained as follows: PL1(d c )=PL1(d c0 )+7.672log 10 (d c )+53.63 (11) The residual sum of squares SSE is used to evaluate the value of the fitting parameter C in step 5, and PL1(d c ) is set as PL i01 (d c ),get: Among them, SSE[PL1(d c )] is the function PL1(d c ), PL i01 (d c ) is the actual measured value of the ith value, PL i1 (d c ) is the function PL1(d c )’s ith predicted value.

7. The method according to claim 6, characterized in that In step 6, the orthogonal hollow metal pipe excited surface wave system model includes two planar magnetic dipole antennas, an orthogonal hollow metal pipe and a pair of coupling devices with adjustable distance; The setting of the measurement scenario includes: fixing the transmitting end and the receiving end of the antenna at the two ends of the orthogonal hollow metal pipe respectively, the transmitting and receiving antennas are oriented orthogonally, adjusting the height control bracket to change the coupling distance, and setting a measurement point every X; performing X1 measurements at each measurement point, and calculating the average path loss; In step 7, the measured data includes the coupling distance d c , and the path loss value of each measurement point.

8. The method according to claim 7, characterized in that In step 8, the path loss attenuation value SZ(d c ) about the coupling distance d c The parameter function model is: SZ(d c )=D log m (d c )+E (13) Among them, D, E, and m are the parameters to be fitted; The path loss attenuation value SZ(d c ) about the coupling distance d c The function is: SZ(d c )=1.198log 10 (d c )+56.27 (14) The residual sum of squares SSE is used to evaluate the values ​​of the fitting parameters D, E, and m in step 8, and SZ(d c ) is set as SZ i0 (d c ),get: Among them, SSE[SZ(d c )] is the function SZ(d c ) of the residual sum of squares, SZ i0 (d c ) is the actual measured value of the ith value, SZ i (d c ) is the function SZ(d c )’s ith predicted value; In step 9, the path loss index NZ(d c ) About the coupling distance d c The parameter function model of is: NZ(d c )=ed c 2 +fd c +g (16) Among them, e, f, and g are the parameters to be fitted; The path loss attenuation value NZ(d c ) about the coupling distance d c The function is: NZ(d c )=-15.15d c 2 +14.88d c +0.2834 (17) The residual sum of squares SSE is used to evaluate the values ​​of the fitting parameters e, f, and g in step 9, and NZ(d c ) is set as NZ i0 (d c ),get: Among them, SSE[NZ(d c )] is the function NZ(d c ), NZ i0 (d c ) is the actual measured value of the ith value, NZ i (d c ) is the function NZ(d c )’s ith predicted value; In step 10, in the scenario of orthogonal metal pipes exciting surface waves, the distance between the antenna transceiver ends is fixed to the distance between the two ends of the metal pipe, and the antenna transceiver ends are oriented orthogonally, that is, d and θ are constants, and d=d0, θ=θ0=90°. The parameter-containing model of the channel path loss function of wireless communication combined with surface waves is constructed as follows: PL2(d c )=PL2(d c0 )+SZ(d c )+F (19) Among them, PL2(d c ) is the surface wave excited by orthogonal metal pipes. c The path loss value at PL2(d c0 ) is the coupling distance d in the scenario of orthogonal metal pipes exciting surface waves c Take the path loss value at the initial value of 0.1cm, and F is the parameter to be fitted; By using the nonlinear least squares method to fit the parameters, the channel path loss model of wireless communication combined with surface waves in the scenario of orthogonal metal pipes exciting surface waves is obtained as follows: PL2(d c )=PL2(d c0 )+1.198log 10 (d c )+59.03 (20) The residual sum of squares SSE is used to evaluate the value of the fitting parameter F in step 10, and PL2(d c ) is set as PL i02 (d c ),get: Among them, SSE[PL2(d c )] is the function PL2(d c ), PL i02 (d c ) is the actual measured value of the ith value, PL i2 (d c ) is the function PL2(d c )’s ith predicted value.

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