Reflection array for enhancing underground non-line-of-sight signals and communication method thereof

Abstract

The invention provides a reflection array for enhancing an underground non-line-of-sight signal and a communication method thereof, and the method comprises the steps: building an underground roadway model with a non-line-of-sight signal region, and setting the initial parameters of the roadway model; a base station is arranged in the roadway, initial parameters of the base station are determined, and first output power of the roadway is obtained through a ray tracing method; constructing reflective arrays, arranging one reflective array in each non-line-of-sight signal area in the roadway, and obtaining second output power of the roadway by using a ray tracing method; and comparing the first output power with the second output power to obtain the enhancement effect of non-line-of-sight signal transmission after the reflective array is arranged in the roadway. The reflection array comprises N * N reflection units which are arranged in a gradient mode according to different phase angles of electromagnetic waves. According to the invention, the coverage range and the transmission distance of the communication signal under the mine can be enhanced, and the transmission quality and the transmission efficiency of the communication signal under the mine are improved.

Description

Technical Field

[0001] This application relates to the field of underground mine wireless communication technology, and in particular, to a reflection array for enhancing non-line-of-sight signals underground and its communication method. Background Art

[0002] The wireless communication distance underground in a mine is affected by factors such as the antenna transmission power, the antenna's received signal sensitivity, the signal gain, and the signal transmission loss. There are many and concentrated electromechanical devices underground in a coal mine. The devices have large power and are frequently started, which causes serious electromagnetic interference underground, restricting the antenna's received signal sensitivity and the antenna gain. Also, considering the issue of safety and explosion protection underground in a coal mine, the size of the antenna is restricted. Therefore, when the antenna transmission power, the antenna's received signal sensitivity, and the signal gain are all restricted, how to reduce the wireless transmission loss underground becomes an effective method to increase the wireless transmission distance underground.

[0003] The electromagnetic reflecting surface is a technology applied to wireless communication and can be used to improve the transmission and coverage of wireless signals. Since there are many non-line-of-sight areas in underground mine wireless communication. For example, the weak and blind areas of non-line-of-sight signals in underground mine roadways. How to use the electromagnetic reflecting surface to enhance the non-line-of-sight signal transmission in the weak and blind areas underground in a mine has become an urgent problem to be solved.

[0004] For the electromagnetic reflecting surface, the reflection characteristics of low frequencies are not as good as those of high-frequency electromagnetic waves. This is because: First, the wavelength of low-frequency electromagnetic waves is not very sensitive to changes in the size of objects, thus reducing the possibility of the electromagnetic waves being reflected, that is, it is difficult to involve the reflecting surface; Second, the propagation of electromagnetic waves in a limited space is extremely complex, increasing the calculation difficulty.

[0005] Therefore, it is necessary to propose a solution to improve one or more problems existing in the above-mentioned related technical solutions.

[0006] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of this application. Therefore, it may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0007] The first aspect of the embodiments of this application provides a reflection array for enhancing non-line-of-sight signals underground. The reflection array includes:

[0008] N×N reflection units arranged in a gradient according to different phase angles of electromagnetic waves. Each reflection unit includes, from top to bottom in sequence:

[0009] A first metal layer, the first metal layer is a cube structure; a square through-hole is provided in the middle of the first metal layer;

[0010] The first dielectric layer, the first dielectric layer is a cube structure; the first dielectric layer is printed on the bottom surface of the first metal layer;

[0011] The second metal layer, the second metal layer is a cube structure, the second metal layer is printed on the bottom surface of the first dielectric layer;

[0012] The second dielectric layer, the second dielectric layer is a cube structure; the second dielectric layer is printed on the bottom surface of the second metal layer;

[0013] The metal bottom plate, the metal bottom plate is a cube structure; the metal bottom plate is printed on the bottom surface of the second dielectric layer;

[0014] Wherein, the size of the square through hole is the same as that of the second metal layer arranged below.

[0015] In an exemplary embodiment of the present application, the phase angles include: 30°, 75°, 120°, 165°, 210°, 255°, 300° and 345°; each of the phase angles corresponds to a reflection array unit of a corresponding size.

[0016] In an exemplary embodiment of the present application, the side lengths of the first dielectric layer and the second dielectric layer are both 40 mm, and the heights of the first dielectric layer and the second dielectric layer are both 3 mm; the side length of the metal bottom plate is 40 mm; the heights of the first metal layer, the second metal layer and the metal bottom plate are all 0.035 mm;

[0017] The side length of the first metal layer corresponding to the phase angle of 30° is 38 mm, and the side length of the second metal layer corresponding to the phase angle of 30° is 36 mm;

[0018] The side length of the first metal layer corresponding to the phase angle of 75° is 37.2 mm, and the side length of the second metal layer corresponding to the phase angle of 75° is 34 mm;

[0019] The side length of the first metal layer corresponding to the phase angle of 120° is 37.6 mm, and the side length of the second metal layer corresponding to the phase angle of 120° is 28 mm;

[0020] The side length of the first metal layer corresponding to the phase angle of 165° is 38 mm, and the side length of the second metal layer corresponding to the phase angle of 165° is 20 mm;

[0021] The side length of the first metal layer corresponding to the phase angle of 210° is 37.6 mm, and the side length of the second metal layer corresponding to the phase angle of 210° is 17 mm;

[0022] The side length of the first metal layer corresponding to the phase angle of 255° is 36.8 mm, and the side length of the second metal layer corresponding to the phase angle of 255° is 12 mm;

[0023] The side length of the first metal layer corresponding to the phase angle of 300° is 33.6 mm, and the side length of the second metal layer corresponding to the phase angle of 300° is 2 mm;

[0024] The side length of the first metal layer corresponding to the phase angle of 345° is 40 mm, and the side length of the second metal layer corresponding to the phase angle of 245° is 36 mm.

[0025] In an exemplary embodiment of the present application, N×N reflection units are gradient arranged according to the generalized Snell's law to obtain an initial reflection array;

[0026] If the reflection angle of the initial reflection array meets the reflection requirements of the downhole non-line-of-sight signal, the initial reflection array is the finally obtained reflection array;

[0027] If the initial reflection array does not meet the reflection requirements, the genetic optimization algorithm is used to optimize N×N reflection units respectively to obtain an optimized reflection array, and the optimized reflection array is used as the finally obtained reflection array.

[0028] In an exemplary embodiment of the present application, the first metal layer, the second metal layer and the metal bottom layer are all made of pure copper, and the loss tangent values of the first metal layer, the second metal layer and the metal bottom layer are all 5.96e+007 S / m;

[0029] FR4 circuit boards are arranged on both the first dielectric layer and the second dielectric layer, and the thickness of the FR4 circuit board is 0.5 nm; the dielectric constants of the first dielectric layer and the second dielectric layer are both εr = 4.3; the dielectric loss angles of the first dielectric layer and the second dielectric layer are both tanδ = 0.0019.

[0030] In a second aspect of the embodiments of the present application, a communication method for enhancing downhole non-line-of-sight signals is provided. The communication method uses the above-mentioned reflection array to be arranged downhole; the communication method includes:

[0031] Establish a roadway model of the downhole area with non-line-of-sight signals, and set the initial parameters of the roadway model; wherein, the roadway model includes at least one type of roadway, and each type of roadway has at least one non-line-of-sight signal area;

[0032] Install a base station in the roadway, determine the initial parameters of the base station, and use the ray tracing method to obtain the first output power of the roadway;

[0033] Construct the reflection array, and arrange one reflection array in each non-line-of-sight signal area in the roadway, and use the ray tracing method to obtain the second output power of the roadway;

[0034] Compare the first output power and the second output power to obtain the enhancement effect of non-line-of-sight signal transmission after arranging the reflection array in the roadway.

[0035] In an exemplary embodiment of the present application, the initial parameters of the roadway model at least include: roadway length, roadway material, roadway dielectric constant, roadway conductivity, and roadway permeability;

[0036] The types of the roadway include one or more of a T-shaped roadway, a C-shaped roadway, and a ladder-shaped roadway;

[0037] The initial parameters of the base station include the antenna height of the base station, the frequency of the base station signal, and the transmission power of the base station signal; wherein, the propagation direction of the base station signal points to the extension direction of the roadway.

[0038] In an exemplary embodiment of the present application, the steps of installing a base station in the roadway, determining the initial parameters of the base station, and using the ray tracing method to obtain the first output power of the roadway include:

[0039] Install the base station at the entrance of the roadway and set the initial parameters of the base station;

[0040] Input both the initial parameters of the base station and the initial parameters of the roadway model into a computer, and use Feko software and the ray tracing method to obtain the first output power.

[0041] In an exemplary embodiment of the present application, the steps of constructing the reflection array, arranging one reflection array in each non-line-of-sight signal area in the roadway, and using the ray tracing method to obtain the second output power of the roadway include:

[0042] Install one reflection array at each turning in the roadway, wherein each turning in the roadway is a non-line-of-sight signal area;

[0043] Input both the initial parameters of the base station and the initial parameters of the roadway model into a computer, and use Feko software and the ray tracing method to obtain the second output power.

[0044] In an exemplary embodiment of the present application, the step of comparing the first output power and the second output power to obtain the enhancement effect of non-line-of-sight signal transmission after arranging the reflection array in the roadway includes:

[0045] Judging the enhancement effect according to the difference between the second output power and the first output power;

[0046] If the second output power is greater than the first output power, arranging the reflection array in the roadway has the effect of enhancing non-line-of-sight signal transmission.

[0047] A reflection array for enhancing non-line-of-sight signals underground and its communication method proposed by the present application. By setting a reflection array with N×N reflection units arranged in a gradient according to electromagnetic waves of multiple phase angles, and comparing the first output power obtained without setting the reflection array in the underground roadway with the second output power obtained after setting the reflection array, the enhancement effect of non-line-of-sight signal transmission after setting the reflection array in the underground roadway is obtained. The present application can enhance the coverage range and transmission distance of communication signals underground, and improve the transmission quality and transmission efficiency of communication signals underground. Description of the Drawings

[0048] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0049] FIG. 1 shows a schematic structural diagram of a reflection unit and a reflection array in an exemplary embodiment of the present application;

[0050] FIG. 2 shows a schematic diagram of the amplitude and phase of a reflection unit in an exemplary embodiment of the present application;

[0051] FIG. 3 shows a phase arrangement diagram, a corresponding direction diagram, and a beam far-field diagram of gradient arrangement of N×N reflection units at different electromagnetic wave phase angles using the generalized Snell's law in an exemplary embodiment of the present application;

[0052] FIG. 4 shows a schematic diagram of optimizing N×N reflection units at different electromagnetic wave phase angles using a genetic optimization algorithm in an exemplary embodiment of the present application;

[0053] Figure 5 FIG. shows a schematic diagram of the steps of a communication method for enhancing non-line-of-sight signals underground in an exemplary embodiment of the present application;

[0054] FIG. 6 shows a schematic diagram of three different types of roadways in an exemplary embodiment of the present application;

[0055] FIG. 7 shows a comparative curve graph of the relationship between distance and received power for three different types of roadways in an exemplary embodiment of the present application with and without a reflection array;

[0056] FIG. 8 shows a schematic diagram of the non-line-of-sight signal enhancement effect of setting a reflection array in three different types of roadways in an exemplary embodiment of the present application. Detailed implementation manners

[0057] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more complete and comprehensive, and the concept of the example embodiments will be fully conveyed to those skilled in the art. The features, structures, or characteristics described can be combined in any suitable manner in one or more embodiments.

[0058] In addition, the accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0059] In a first aspect of this example embodiment, a reflection array for enhancing non-line-of-sight signals underground is provided, as Figure 1a and Figure 1b shown. The reflection array includes:

[0060] N×N reflection units arranged in a gradient according to different phase angles of electromagnetic waves. Each of the reflection units includes, sequentially arranged from top to bottom:

[0061] A first metal layer, the first metal layer having a cube structure; a square through hole is provided in the middle of the first metal layer;

[0062] A first dielectric layer, the first dielectric layer having a cube structure; the first dielectric layer is printed on the bottom surface of the first metal layer;

[0063] A second metal layer, the second metal layer having a cube structure, the second metal layer is printed on the bottom surface of the first dielectric layer;

[0064] A second dielectric layer, the second dielectric layer being a cube structure; the second dielectric layer is printed on the bottom surface of the second metal layer;

[0065] A metal bottom plate, the metal bottom plate being a cube structure; the metal bottom plate is printed on the bottom surface of the second dielectric layer;

[0066] Wherein, the square through-hole has the same size as the second metal layer provided below.

[0067] In a second aspect of the exemplary embodiment, a communication method for enhancing non-line-of-sight signals underground is provided. This communication method utilizes the reflection array proposed in the first aspect of the exemplary embodiment and is arranged underground. This communication method may include the following steps:

[0068] Step S101: Establish a roadway model of the underground area with non-line-of-sight signals and set the initial parameters of the roadway model; wherein, the roadway model includes at least one type of roadway, and each type of the roadway has at least one non-line-of-sight signal area.

[0069] Step S102: Set up a base station in the roadway, determine the initial parameters of the base station, and use the ray tracing method to obtain the first output power of the roadway.

[0070] Step S103: Construct a reflection array, and arrange a reflection array in each non-line-of-sight signal area in the roadway, and use the ray tracing method to obtain the second output power of the roadway.

[0071] Step S104: Compare the first output power and the second output power to obtain the enhancement effect of non-line-of-sight signal transmission after arranging the reflection array in the roadway.

[0072] In the embodiment of the present application, a reflection array for enhancing non-line-of-sight signals underground and its communication method are proposed. By setting a reflection array composed of N×N reflection units arranged in a gradient according to different phase angles of electromagnetic waves, and comparing the first output power obtained without setting this reflection array in the underground roadway with the second output power obtained after setting this reflection array, the enhancement effect of non-line-of-sight signal transmission after setting this reflection array in the underground roadway is obtained. Thus, it can enhance the coverage range and transmission distance of communication signals underground, and improve the transmission quality and transmission efficiency of communication signals underground.

[0073] Next, the structure and steps of the above-mentioned reflection array for enhancing non-line-of-sight signals underground and its communication method in the exemplary embodiment will be described in more detail.

[0074] A first aspect of an embodiment of the present application proposes a reflective array. As shown in FIG. 1, the reflective array combines the phase response of local electromagnetic waves and the generalized Snell's law, and arranges the phase response reflecting units on the surface of the reflective array according to the gradient phase. In this way, a reflective array that can regulate the outgoing angle of incident electromagnetic waves within a certain range can be obtained. Specifically:

[0075] As shown in FIG. 2, the reflective array is composed of N×N reflecting units. These reflecting units are divided into 8 structural types according to their respective geometric dimensions, and each corresponds to electromagnetic waves with different phase angles. The generalized Snell's law is used to arrange these reflecting units into the reflective array according to the phase gradient.

[0076] The structure of each reflecting unit is as follows:

[0077] Each reflecting unit includes, from top to bottom in sequence: a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, and a metal bottom plate.

[0078] The first metal layer is a cube structure, and a square through hole is provided in the middle position.

[0079] The first dielectric layer is a cube structure, and the first dielectric layer is printed on the bottom surface of the first metal layer.

[0080] The second metal layer is a cube structure, and the second metal layer is printed on the bottom surface of the first dielectric layer.

[0081] The second dielectric layer is a cube structure, and the second dielectric layer is printed on the bottom surface of the second metal layer.

[0082] The metal bottom plate is a cube structure, and the metal bottom plate is printed on the bottom surface of the second dielectric layer.

[0083] Among them, the size of the square through hole is the same as that of the second metal layer provided below.

[0084] Furthermore, the side length of each reflecting unit is 40 mm. In this embodiment, the reflecting units are divided into different types according to their respective size specifications. Each type of reflecting unit corresponds to electromagnetic waves with different phase angles. Specifically as follows:

[0085] The phase angles of the electromagnetic waves are respectively: 30°, 75°, 120°, 165°, 210°, 255°, 300°, and 345°.

[0086] Consisting of Figure 2a and Figure 2bIt can be seen that 000 represents 30°; 001 represents 75°; 010 represents 120°; 011 represents 165°; 100 represents 210°; 101 represents 255°; 110 represents 300°; 111 represents 345°. Through Figure 2, the fluctuations of the frequencies corresponding to the amplitudes and phases of the reflection units with different phase angles in the entire reflection array can be clearly seen.

[0087] Furthermore, the side lengths of both the first dielectric layer and the second dielectric layer are 40 mm, and the heights of both the first dielectric layer and the second dielectric layer are 3 mm; the side length of the metal bottom plate is 40 mm; the heights of the first metal layer, the second metal layer, and the metal bottom plate are all 0.035 mm; on this basis,

[0088] The side length of the first metal layer corresponding to the phase angle of 30° is 38 mm, and the side length of the second metal layer corresponding to the phase angle of 30° is 36 mm;

[0089] The side length of the first metal layer corresponding to the phase angle of 75° is 37.2 mm, and the side length of the second metal layer corresponding to the phase angle of 75° is 34 mm;

[0090] The side length of the first metal layer corresponding to the phase angle of 120° is 37.6 mm, and the side length of the second metal layer corresponding to the phase angle of 120° is 28 mm;

[0091] The side length of the first metal layer corresponding to the phase angle of 165° is 38 mm, and the side length of the second metal layer corresponding to the phase angle of 165° is 20 mm;

[0092] The side length of the first metal layer corresponding to the phase angle of 210° is 37.6 mm, and the side length of the second metal layer corresponding to the phase angle of 210° is 17 mm;

[0093] The side length of the first metal layer corresponding to the phase angle of 255° is 36.8 mm, and the side length of the second metal layer corresponding to the phase angle of 255° is 12 mm;

[0094] The side length of the first metal layer corresponding to the phase angle of 300° is 33.6 mm, and the side length of the second metal layer corresponding to the phase angle of 300° is 2 mm;

[0095] The side length of the first metal layer corresponding to the phase angle of 345° is 40 mm, and the side length of the second metal layer corresponding to the phase angle of 245° is 36 mm.

[0096] Furthermore, as shown in Figure 3, the reflection array arranges the N×N reflection units in a gradient manner according to the generalized Snell's law to obtain an initial reflection array.

[0097] If the reflection angle of the initial reflection array meets the reflection requirements of the downhole non-line-of-sight signal, the initial reflection array is the finally obtained reflection array;

[0098] If the initial reflection array does not meet the reflection requirements, the genetic optimization algorithm is used to optimize the N×N reflection units to obtain the optimized reflection array, and the optimized reflection array is used as the finally obtained reflection array.

[0099] Here, the beam angle reflected by the reflection array is only used to prove that the reflection array can deflect the beam of electromagnetic waves within a certain angle. The genetic algorithm can further expand the ability of the beam deflection angle. At the same time, the reflection array can also be incident obliquely so that the reflected beam can propagate along the direction of the roadway extension.

[0100] It can be seen that Figure 3a shows the arrangement of the N×N reflection units, the corresponding direction pattern and the beam far-field pattern when the reflection angle of the electromagnetic wave reflected by the reflection array is 15°. Figure 3b shows the arrangement of the N×N reflection units, the corresponding direction pattern and the beam far-field pattern when the reflection angle of the electromagnetic wave reflected by the reflection array is 25°. Figure 3c shows the arrangement of the N×N reflection units, the corresponding direction pattern and the beam far-field pattern when the reflection angle of the electromagnetic wave reflected by the reflection array is 35°.

[0101] As can be seen from Fig. 4, when the angle is between 15° and 55°, it is the beam adjustable range of the reflection array composed of the N×N reflection units. It can be seen that there is a high-gain effect with low side lobes within this angle range. When the angle exceeds 55°, obvious side lobes will appear. Therefore, the range of 15° - 55° is taken as the achievable range of beam deflection. This proves that the beam of the reflection array in this application has good directivity. Fig. 4 is for example to illustrate the effect within the range of 15° - 55°. Figure 4a The corresponding one is 45°, Figure 4b The corresponding one is 50°.

[0102] Fig. 3 and Fig. 4 reflect the ability of the reflection array to adjust the beam deflection angle, and do not correspond one by one to the 8 phase angles. The calculation formula for the gradient phase requirement here is: Among them, represents the gradient phase requirement, θ i represents the incident angle, θ r represents the reflection angle, k represents the beam, k = 2π / λ, and λ is the wavelength. It can be known that under the same gradient requirement, there are countless groups of solutions for and. is the incident wave from the base station antenna, and is the beam angle reflected by the reflection array, that is, beam regulation or beam deflection, so that it can point to the non-line-of-sight signal area or the direction of the roadway extension.

[0103] The beam far-field patterns in FIGS. 3 and 4 are for more intuitive representation.

[0104] Furthermore, the first metal layer, the second metal layer, and the metal bottom layer are all made of pure copper, and the loss tangent values of the first metal layer, the second metal layer, and the metal bottom layer are all 5.96e+007 S / m.

[0105] FR4 circuit boards are provided on both the first dielectric layer and the second dielectric layer; the thickness of the FR4 circuit board is 0.5 nm; the dielectric constants of the first dielectric layer and the second dielectric layer are both εr = 4.3; the dielectric loss angles of the first dielectric layer and the second dielectric layer are both tanδ = 0.0019.

[0106] In a second aspect of the embodiment of the present application, a communication method for enhancing non-line-of-sight signals underground is proposed. This communication method utilizes the above reflection array to arrange the underground roadway. As Figure 5 shown, this communication method includes:

[0107] Step S101: Establish a roadway model for the area with non-line-of-sight signals underground and set the initial parameters of the roadway model; wherein, the roadway model includes at least one type of roadway, and each type of the roadway has at least one non-line-of-sight signal area.

[0108] Step S102: Set up a base station in the roadway, determine the initial parameters of the base station, and use the ray tracing method to obtain the first output power of the roadway.

[0109] Step S103: Construct a reflection array and arrange a reflection array in each non-line-of-sight signal area in the roadway, and use the ray tracing method to obtain the second output power of the roadway.

[0110] Step S104: Compare the first output power and the second output power to obtain the enhancement effect of non-line-of-sight signal transmission after arranging the reflection array in the roadway.

[0111] The following details each step of this communication method.

[0112] In step S101, the roadway model of this embodiment includes one or more of T-shaped roadways, C-shaped roadways, and ladder-shaped roadways. The initial parameter data of the roadway includes: roadway length, roadway material, roadway dielectric constant, roadway conductivity, and roadway permeability.

[0113] The roadway length is further divided into horizontal roadway length and vertical roadway length.

[0114] The width and height of the roadway are both 5 m, and the cross-section of the roadway is rectangular.

[0115] All types of roadways are made of concrete.

[0116] The dielectric constant of the roadway is 4.3.

[0117] The conductivity of the roadway is 0.005 S / m.

[0118] The permeability of the roadway is close to that of a vacuum.

[0119] As shown in Figure 6, Figure 6 shows different types of roadways.

[0120] In this embodiment, Figure 6a in the T-shaped roadway, the length of the horizontal roadway is 200 m; the length of the vertical roadway is 65 m. The intersection position of the horizontal roadway and the vertical roadway is the non-line-of-sight signal area.

[0121] In Figure 6b in the C-shaped roadway, the length of each horizontal roadway is 200 m; the length of the vertical roadway is 50 m. The connection corner position of each horizontal roadway and the vertical roadway is the non-line-of-sight signal area.

[0122] In Figure 6c in the trapezoidal roadway, the length of each horizontal roadway is 200 m; the vertical roadway is 50 m. The connection corner position of each horizontal roadway and the vertical roadway is the non-line-of-sight signal area.

[0123] Step S102 includes the following sub-steps:

[0124] Sub-step S1021: Set up a base station at the entrance of the roadway and determine the initial parameters of the base station.

[0125] In this sub-step, the initial parameters of the base station include the antenna height of the base station, the frequency of the communication signal of the base station, and the transmission power of the communication signal. The propagation direction of the communication signal of the base station points to the extension direction of the roadway.

[0126] In the embodiment, the operating frequency of the communication signal of the base station is 900 MHz. The electromagnetic waves in this frequency band have the characteristics of low propagation loss, wide coverage, strong penetration ability, and low network deployment cost. Therefore, in this embodiment, the base station built using the low-frequency 900 MHz has a larger coverage area, does not require ultra-dense networking, can greatly reduce the network construction cost, and save energy and reduce emissions. Especially in the coal mine underground, compared with other frequency bands, the 900 MHz frequency band has the advantages of low signal transmission loss, long wireless transmission distance, and strong diffraction ability.

[0127] Furthermore, in this embodiment, the antenna height is set to 2 m. The transmission power of the communication signal is set to 200 MW. The antenna is a unidirectional antenna, and the propagation direction of the communication signal points to the extension direction of the roadway.

[0128] Sub-step S1022: Input the initial parameters of the base station and the initial parameter data of the roadway model into a computer respectively, and use the Feko software and the ray-tracing method to obtain the first output power.

[0129] Further, as shown in FIGS. 7 and 8, the ray-tracing method can be used to calculate the propagation characteristics of electromagnetic waves and verify the feasibility of the reflection array for enhancing non-line-of-sight signals. The standard ray-tracing model performs strict 3D ray-tracing prediction. Although the calculation results have high accuracy, the cost is a large amount of calculation. The deterministic model is used to model the physical propagation of radio waves and can accurately consider the influence of the roadway environment on the propagation parameters.

[0130] Here, the simulation accuracy of the Feko software is set to 0.2 m. In this embodiment, the initial parameters of the base station and the initial parameter data of the roadway model are input into a computer respectively to obtain the first output power. As Figure 7a 、 7c shown in FIGS. 7e, the intensity of the communication signals transmitted by the antennas of the base station is all within -60 dBm, which can meet the high-quality communication requirements, while there are basically no communication signals in the non-line-of-sight signal area. This visualization effect can be seen from FIG. 8.

[0131] For the calculation of electromagnetic waves, not only the free-space loss needs to be considered, but also the losses caused by transmission, reflection, and multiple diffractions need to be considered. This requires using a physical deterministic model or an empirical model to complete. Due to the characteristics of the roadway wall, the reflection model considers second-order reflection and temporarily ignores the scattering factor because after two reflections, the scattered energy is very small and can be ignored. As can be seen from FIG. 7, at a working frequency of 900 MHz, as the distance increases, the received power shows a gradually decreasing trend, which indicates that the closer to the base station, the faster the intensity loss of the electromagnetic wave; conversely, the farther from the base station, the smaller the loss rate of the electromagnetic wave with distance. Therefore, the electromagnetic wave can also propagate a long distance at a relatively low power. As can also be seen from FIG. 7, when the reflection array is not set, the electromagnetic wave has no ability to reflect into the non-line-of-sight signal area, and the communication signal can only reach the roadway turning point. This visualization effect can also be seen from FIG. 8, and the communication signals in the non-line-of-sight signal area are interrupted.

[0132] Step S103 includes the following sub-steps:

[0133] Sub-step S1031: Construct a reflection array.

[0134] In this embodiment, the operating frequency band of the reflection array is 900 MHz

[0135] Sub-step S1032: The non-line-of-sight signal area is each turning point of the roadway, and a reflection array is set at each turning point respectively.

[0136] Sub-step S1033: Input the initial parameters of the base station and the initial parameters of the roadway into a computer respectively, and use the Feko software and the ray tracing method to obtain the second output power.

[0137] As Figure 8a , 8b and 8c, it can be seen that a base station is set at the entrance of the roadway, and a reflection array is set at each turning of the roadway. Similarly, the simulation accuracy of the Feko software is set to 0.2m here. In this embodiment, the initial parameters of the base station and the initial parameter data of the roadway model are input into the computer respectively, and the second output power obtained is.

[0138] As Figure 7b and Figure 7d shown, after being reflected by the reflection array, the communication signal intensity emitted by the antenna of the base station is almost within -100dBm. Figure 7f Because there are two reflection arrays, the signal is reflected 2 times, and some energy is additionally lost, but it almost meets the high communication requirement of -105dBm, and the non-line-of-sight signal area is covered by the signals reflected by the reflection array. The visualization effect can be seen in Figure 8.

[0139] Figure 8 shows that by arranging the reflection array, without adding more base stations, the signal intensity in the non-line-of-sight signal area can reach the expected effect and meet the communication requirements. Arranging such a reflection array is not only simple and easy to implement, but also has no energy consumption and no safety hazards.

[0140] From Figure 8a it can be seen that when there is no reflection array arranged in the T-shaped roadway, there is a non-line-of-sight signal blind area in the roadway. After arranging the reflection array, the relative communication signal source has a beam deflection of ±60°, and the calculated minimum received power is -105dBm, meeting the communication requirements in the underground roadway.

[0141] From Figure 8b it can be seen that when there is no reflection array arranged in the C-shaped roadway, there is a non-line-of-sight signal blind area. Since the total length of the roadway is relatively long, the non-line-of-sight signal area is relatively large, and a reflection array needs to be set at the intersection of each horizontal roadway and vertical roadway respectively. The set reflection arrays can reflect the main beam of 60°. After the arrangement is completed, the minimum received power is within -105dBm, which can meet the communication requirements in the underground roadway.

[0142] From Figure 8c it can be seen that by comparing the received power before and after arranging the reflection array in the trapezoidal roadway, it can be found that since the total length of the trapezoidal roadway is less than that of the C-shaped roadway, the signal enhancement effect in the trapezoidal roadway is significantly better than that in the C-shaped roadway. Only a small part of the received power is less than -120dBm, and most of the area is a high-quality communication area.

[0143] As can be seen, both FIG. 7 and FIG. 8 show the variation characteristics of 900 MHz electromagnetic waves with and without the reflection array arranged in the base station. FIG. 7 can intuitively distinguish the magnitude of the received power value and its changing trend in the form of a specific numerical curve. FIG. 8 visually shows the distribution of the received power in the roadway in the form of a top view.

[0144] Figure 7a is the curve of the received power varying with the base station distance when there is no reflection array arranged in the T-shaped roadway, and the signal stops transmitting at 200 m. Figure 7b By installing a reflecting surface and transmitting to two non-line-of-sight areas of 30 m each up and down, it can reach within -100 dBm. Figure 7c is the curve of the received power varying with the base station distance when there is no reflection array arranged in the C-shaped roadway. Figure 7d By installing a reflecting surface and transmitting to a non-line-of-sight area of 185 m, it can reach within -100 dBm. Figure 7e is the curve of the received power varying with the base station distance when there is no reflection array arranged in the ladder-shaped roadway, and the signal stops transmitting at 130 m. Figure 7f By installing reflecting surfaces at both turning points, the first reflecting surface transmits to a non-line-of-sight area of 40 m, and the signal transmitted by the second reflecting surface can basically reach within -100 dBm.

[0145] Figure 8a The result for the T-shaped roadway visually shows the coverage of the entire roadway, and one reflecting surface covers a short non-line-of-sight area to meet the communication requirements. Figure 8b The result for the C-shaped roadway visually shows the coverage of the entire roadway, and one reflecting surface covers a long non-line-of-sight area to meet the communication requirements, strongly proving the enhancement of the coverage of non-line-of-sight signals by the reflecting surface. Figure 8c The result for the ladder-shaped roadway visually shows the coverage of the entire roadway, and two reflecting surfaces basically meet the communication requirements to cover two consecutive non-line-of-sight areas, verifying the feasibility of multiple reflections of the reflecting surface in a complex environment.

[0146] In step S104, after obtaining the first output power and the second output power, in order to judge the enhancement effect of the non-line-of-sight signal transmission after arranging the reflection array, it is necessary to compare according to the difference between the second output power and the first output power.

[0147] If the second output power is greater than the first output power, arranging the reflection array in the roadway has the effect of enhancing non-line-of-sight signal transmission.

[0148] If the second output power is equal to or less than the first output power, this indicates that there is no enhancement effect or the signal transmission effect is weakened.

[0149] In summary, a reflective array and its communication method for enhancing non-line-of-sight signals underground are proposed in this application. First, by controlling the radiation direction of electromagnetic waves, the transmission range and coverage area of non-line-of-sight signals underground can be effectively expanded. Second, signal attenuation is reduced, and low-frequency signals attenuate less during propagation, which can better overcome the obstruction of obstacles. Third, the influence of external interference on the signal can be reduced, and the anti-interference ability of the signal is improved. Finally, it can also be applied to other environments such as cities, indoors, or complex terrains. Low-frequency signals can better penetrate buildings or obstacles, enhancing the penetration ability and adaptability of the signals.

[0150] It should be noted that although several units of the system for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiments of the present application, the features and functions of two or more of the above-described units can be embodied in one unit. Conversely, the features and functions of one unit described above can be further divided and embodied by multiple units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the present application. Those of ordinary skill in the art can understand and implement it without creative effort.

[0151] Those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of the present application and include known common knowledge or conventional technical means in the technical field not disclosed in the present application.

Claims

1. A reflective array for enhancing non-line-of-sight signals in a mine, characterized in that, The reflective array includes: N×N reflective units arranged in a gradient according to different phase angles of electromagnetic waves. Each of the reflective units includes, from top to bottom in sequence: A first metal layer, which is a cube structure; a square through-hole is provided in the middle of the first metal layer; A first dielectric layer, which is a cube structure; the first dielectric layer is printed on the bottom surface of the first metal layer; A second metal layer, which is a cube structure, and the second metal layer is printed on the bottom surface of the first dielectric layer; A second dielectric layer, which is a cube structure; the second dielectric layer is printed on the bottom surface of the second metal layer; A metal bottom plate, which is a cube structure; the metal bottom plate is printed on the bottom surface of the second dielectric layer; Wherein, the size of the square through-hole is the same as that of the second metal layer provided below.

2. The reflective array for enhancing non-line-of-sight signals in a mine according to claim 1, characterized in that, The phase angles include: 30°, 75°, 120°, 165°, 210°, 255°, 300° and 345°; each of the phase angles corresponds to a reflective array unit of a corresponding size.

3. The reflective array for enhancing non-line-of-sight signals in a mine according to claim 2, characterized in that, The side lengths of the first dielectric layer and the second dielectric layer are both 40 mm, and the heights of the first dielectric layer and the second dielectric layer are both 3 mm; the side length of the metal bottom plate is 40 mm; the heights of the first metal layer, the second metal layer and the metal bottom plate are all 0.035 mm; The side length of the first metal layer corresponding to the phase angle of 30° is 38 mm, and the side length of the second metal layer corresponding to the phase angle of 30° is 36 mm; The side length of the first metal layer corresponding to the phase angle of 75° is 37.2 mm, and the side length of the second metal layer corresponding to the phase angle of 75° is 34 mm; The side length of the first metal layer corresponding to the phase angle of 120° is 37.6 mm, and the side length of the second metal layer corresponding to the phase angle of 120° is 28 mm; The side length of the first metal layer corresponding to the phase angle of 165° is 38 mm, and the side length of the second metal layer corresponding to the phase angle of 165° is 20 mm; The side length of the first metal layer corresponding to the phase angle of 210° is 37.6 mm, and the side length of the second metal layer corresponding to the phase angle of 210° is 17 mm; The side length of the first metal layer corresponding to the phase angle of 255° is 36.8 mm, and the side length of the second metal layer corresponding to the phase angle of 255° is 12 mm; The side length of the first metal layer corresponding to the phase angle of 300° is 33.6 mm, and the side length of the second metal layer corresponding to the phase angle of 300° is 2 mm; The side length of the first metal layer corresponding to the phase angle of 345° is 40 mm, and the side length of the second metal layer corresponding to the phase angle of 245° is 36 mm.

4. The reflective array for enhancing non-line-of-sight signals in a mine according to claim 3, characterized in that, The N×N reflective units are arranged in a gradient according to the generalized Snell's law to obtain an initial reflective array; If the reflection angle of the initial reflection array meets the reflection requirements of the downhole non-line-of-sight signal, then the initial reflection array is the finally obtained reflection array; If the initial reflection array does not meet the reflection requirements, then the genetic optimization algorithm is used to optimize each of the N×N reflection units respectively to obtain an optimized reflection array, and the optimized reflection array is used as the finally obtained reflection array.

5. The reflective array for enhancing non-line-of-sight signals in a mine according to claim 3, characterized in that, The first metal layer, the second metal layer, and the metal bottom layer are all made of pure copper, and the loss tangent values of the first metal layer, the second metal layer, and the metal bottom layer are all 5.96e+007 S / m; FR4 circuit boards are arranged on both the first dielectric layer and the second dielectric layer, and the thickness of the FR4 circuit board is 0.5 nm; the dielectric constants of the first dielectric layer and the second dielectric layer are both εr = 4.3; the dielectric loss angles of the first dielectric layer and the second dielectric layer are both tanδ = 0.0019.

6. A communication method for enhancing non-line-of-sight signals in a mine, characterized in that, This communication method uses the reflection array described in any one of claims 1-5 to be arranged downhole; the communication method includes: Establish a roadway model of the downhole area with non-line-of-sight signals and set the initial parameters of the roadway model; wherein, the roadway model includes at least one type of roadway, and each type of roadway has at least one non-line-of-sight signal area; Set up a base station in the roadway, determine the initial parameters of the base station, and use the ray tracing method to obtain the first output power of the roadway; Construct the reflection array and arrange one reflection array in each non-line-of-sight signal area in the roadway, and use the ray tracing method to obtain the second output power of the roadway; Compare the first output power and the second output power to obtain the enhancement effect of non-line-of-sight signal transmission after arranging the reflection array in the roadway.

7. The communication method for enhancing non-line-of-sight signals in a mine according to claim 6, characterized in that, The initial parameters of the roadway model at least include: roadway length, roadway material, roadway dielectric constant, roadway conductivity, and roadway permeability; The types of the roadway include one or more of T-shaped roadways, C-shaped roadways, and ladder-shaped roadways; The initial parameters of the base station include the antenna height of the base station, the frequency of the base station signal, and the transmission power of the base station signal; wherein, the propagation direction of the base station signal points to the extension direction of the roadway.

8. The communication method for enhancing non-line-of-sight signals underground according to claim 7, wherein, The steps of setting up a base station in the roadway, determining the initial parameters of the base station, and using the ray tracing method to obtain the first output power of the roadway include: Set up the base station at the entrance of the roadway and set the initial parameters of the base station; Input both the initial parameters of the base station and the initial parameters of the roadway model into a computer, and use Feko software and the ray tracing method to obtain the first output power.

9. The communication method for enhancing non-line-of-sight signals underground according to claim 8, wherein, The steps of constructing the reflection array, arranging one reflection array in each non-line-of-sight signal area in the roadway, and using the ray tracing method to obtain the second output power of the roadway include: A reflection array is provided at each turning in the roadway, wherein each turning in the roadway is a non-line-of-sight signal area; The initial parameters of the base station and the initial parameters of the roadway model are both input into a computer, and the second output power is obtained by using Feko software and the ray tracing method.

10. The communication method for enhancing non-line-of-sight signals underground according to claim 9, wherein, The step of comparing the first output power and the second output power to obtain the enhancement effect of non-line-of-sight signal transmission after arranging the reflection array in the roadway includes: Judging the enhancement effect according to the difference between the second output power and the first output power; If the second output power is greater than the first output power, arranging the reflection array in the roadway has the effect of enhancing non-line-of-sight signal transmission.

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