Wireless transmission system

Abstract

The invention provides a wireless transmission system which improves a radio wave propagation environment and inhibits radio waves from escaping out of a necessary space. This wireless transmission system is provided with: a base station that performs wireless communication in a prescribed frequency band selected from among frequencies of 1 GHz to 300 GHz (inclusive); and an electromagnetic wave reflecting device having a reflecting panel for reflecting the electromagnetic wave of the predetermined frequency band, the electromagnetic wave reflecting device being disposed in a communication area of the base station, the electromagnetic wave reflecting device being disposed at a position lower than the uppermost position of the reflecting surface of the reflecting panel in the electromagnetic wave emitted from the base station. The electromagnetic wave reflecting device reflects the electromagnetic waves incident on the reflecting panel to a position lower than an incident position.

Description

Technical Field

[0001] The present invention relates to a wireless transmission system. Background Art

[0002] For the purpose of realizing the automation of manufacturing processes, office work, remote operation, AI (Artificial Intelligence)-based control and management, autonomous driving, etc., the introduction of wireless base stations indoors and outdoors is in progress. In addition to indoors such as factories, workshops, offices, and commercial facilities, and outdoors such as highways and railway lines, wireless base stations have also been introduced in scenarios regardless of indoors or outdoors such as medical sites and event venues.

[0003] In the fifth-generation mobile communication standard (hereinafter referred to as "5G"), a frequency band of 6 GHz or less called "sub-6" and a 28 GHz frequency band classified as a millimeter wave band are provided. In the next-generation 6G mobile communication standard, it is expected to be extended to the sub-terahertz band. By using such a high-frequency band, the communication bandwidth is greatly expanded, and a large amount of data communication can be performed with low latency. A structure in which electromagnetic reflection devices are arranged along at least a part of a production line in a factory has been proposed (for example, refer to Patent Document 1).

[0004] Patent Document 1: International Publication No. 2021 / 199504

[0005] When applying local 5G radio waves indoors and outdoors, there are usually multiple structures and moving objects at the location where the base station is introduced, and blind spots where radio waves are difficult to reach due to being blocked by these structures and objects may occur. Simply increasing the number of base stations increases the cost but it is difficult to eliminate the blind spots. It is necessary to consider minimizing the addition of base stations and how to improve the utilization efficiency of radio waves. On the other hand, if the local 5G radio waves reach outside the application area, interference with other commercial radio waves may occur. It is required to balance the improvement of blind spots and the suppression of radio waves from escaping to the outside. Summary of the Invention

[0006] An object of the present invention is to provide a wireless transmission system that balances the improvement of the radio wave environment and the suppression of radio waves from escaping to the space outside the necessary area.

[0007] In one embodiment, the wireless transmission system includes:

[0008] a base station that performs wireless communication in a specified frequency band selected from frequencies of 1 GHz or more and 300 GHz or less; and

[0009] an electromagnetic wave reflection device having a reflection panel that reflects electromagnetic waves in the specified frequency band, and the electromagnetic wave reflection device is arranged within the communication area of the base station,

[0010] The electromagnetic wave radiated from the above base station hits a position on the reflecting surface of the above reflecting panel that is lower than the uppermost position.

[0011] The above electromagnetic wave reflection device reflects the above electromagnetic wave incident on the above reflecting panel downward from the incident position.

[0012] Implement a wireless transmission system that takes into account both the improvement of the radio wave environment and the suppression of radio wave leakage outside the necessary space. Description of the Drawings

[0013] Figure 1A It is a schematic diagram showing a configuration example of the wireless transmission system of the embodiment.

[0014] Figure 1B It is a schematic diagram showing another configuration example of the wireless transmission system.

[0015] Figure 1C It is a schematic diagram showing yet another configuration example of the wireless transmission system.

[0016] Figure 2 It is a schematic diagram of the electromagnetic wave reflection device used in the wireless transmission system.

[0017] Figure 3 It is a schematic diagram of the electromagnetic wave reflection fence formed by connecting electromagnetic wave reflection devices.

[0018] Figure 4 It is a schematic diagram showing a modified example of the electromagnetic wave reflection fence.

[0019] Figure 5 It is the A-A line along the Figure 4 of the horizontal cross-section configuration example.

[0020] Figure 6 It is Figure 4 a top view of the connecting part C of

[0021] Figure 7 It is a diagram showing another connection example of the electromagnetic wave reflection fence.

[0022] Figure 8 It is a diagram showing yet another arrangement example of the electromagnetic wave reflection fence.

[0023] Figure 9 It is a plan view showing another arrangement example of the electromagnetic wave reflection fence.

[0024] Figure 10 It is a plan view showing an arrangement example of the electromagnetic wave reflection device. Detailed Implementation Manner

[0025] In an embodiment, in a wireless transmission system used indoors and outdoors, an electromagnetic wave reflection device is used to improve blind spots and suppress the leakage of radio waves to the outside. In this specification, a "blind spot" refers to a zone where the received power is reduced by 10 dB or more compared to the surrounding receiving environment without obstructions due to the influence of obstructions. Generally, electromagnetic waves below 3 THz are called radio waves, but in this specification, the communication wave transmitted from the base station is called a "radio wave", and general electromagnetic waves are called "electromagnetic waves".

[0026] The blind spot includes not only a two-dimensional area but also a three-dimensional space. If production equipment, sensors, mobile communication terminals, etc. with wireless communication functions are located in the blind spot, it is difficult to transmit and receive signals between them and the base station. Therefore, an electromagnetic wave reflection device is introduced to reduce the blind spot and improve the radio wave environment. By devising the positional relationship and configuration structure between the electromagnetic wave reflection device and the base station, the radio wave with strong linear propagation is suppressed from leaking out of the area where the radio wave is used.

[0027] Hereinafter, with reference to the drawings, the structure of the wireless transmission system according to the embodiment will be described. The following-described mode is an example for embodying the technical idea of the present invention and does not limit the present invention. Sometimes, the sizes, positional relationships, etc. of the components shown in the respective drawings are exaggerated for easy understanding of the invention. In the following description, the same reference numerals or names may be given to the same components or functions, and repeated descriptions may be omitted.

[0028] <Wireless Transmission System>

[0029] Figure 1A is a schematic diagram of the wireless transmission system 1A according to the embodiment. The wireless transmission system 1A is installed indoors and outdoors and supports wireless communication in a specified frequency band selected from a range of at least 1 GHz or more and 170 GHz or less, preferably 1 GHz or more and 300 GHz or less. The wireless transmission system 1A includes: a base station 31 that transmits and receives signals in the specified frequency band included in the above frequency range; and an electromagnetic wave reflection device 60A that reflects electromagnetic waves in the frequency band used by the base station 31. In Figure 1A the coordinate system, the installation surface P on which the electromagnetic wave reflection device 60A is placed is set as the XY plane, and the height direction orthogonal to the XY plane is set as the Z direction.

[0030] The antenna of base station 31 has directivity and gain selected according to the width, shape, usage, etc. of the space into which base station 31 is introduced. As an example, the base station 31 of the embodiment has an antenna with a maximum gain of 5 dBi or more and 30 dBi or less. The electromagnetic wave radiated from base station 31 hits a position lower than the highest position on the reflecting surface 105 of the electromagnetic wave reflecting device 60A. That is, the beam cross-section of the electromagnetic wave emitted from base station 31 incident on the reflecting surface 105 is located below the uppermost end of the reflecting surface 105. The beam cross-section incident on the reflecting surface 105 can also be said to be the width of the beam when the electromagnetic wave emitted from base station 31 enters the reflecting surface 105 with a power of half (-3 dB) or more of the maximum value of the power of the electromagnetic wave emitted from base station 31. This beam width is called the "3 dB beam width". If the position of the beam cross-section incident on the electromagnetic wave reflecting device 60A is lower than the uppermost end of the reflecting surface and the incident beam is reflected downward from the incident position, the position of the antenna of base station 31 itself can be located higher than the upper end of the electromagnetic wave reflecting device 60A or lower than the upper end.

[0031] In the environment where base station 31 is used, there are structures 20 such as shelves, racks, and columns. In Figure 1A , the place where base station 31 is introduced is, for example, the production line 3 where production machinery is present. The production machinery used in production line 3 has a wireless terminal 34 that communicates with base station 31, and the production machinery itself may become a structure 20 that shields the radio waves from base station 31. From the perspective of the antenna of base station 31, the area behind structure 20 is a blind area 30 with poor visibility (NLOS: Non-Line-of-Sight). In blind area 30, the received power is reduced by 10 dB or more compared to the surrounding reception environment where it is not blocked by structure 20. If wireless terminal 34 is located in blind area 30, signals cannot be transmitted and received between it and base station 31. Wireless terminal 34 also includes mobile terminals such as smartphones and sensor devices fixed at specified positions.

[0032] The electromagnetic wave reflecting device 60A causes the radio waves from base station 31 to reach the blind area 30, improving the radio wave environment. The electromagnetic wave reflecting device 60 has a reflecting panel 10 that reflects electromagnetic waves of the frequency used by base station 31. The electromagnetic wave reflecting device 60A may also have legs 56 to stand independently on the installation surface P. In Figure 1A 's example, the reflecting panel 10 is supported on the legs 56 at an angle substantially perpendicular to the installation surface P. When it is called "substantially perpendicular", it includes a range of 90° ± 10° that can stand stably with respect to the installation surface P. Casters with locks can also be provided on the legs 56, enabling the electromagnetic wave reflecting device 60A to be moved and installed at a desired location. Instead of using the legs 56, the electromagnetic wave reflecting device 60A can also be installed on a wall or ceiling.

[0033] The reflecting surface 105 of the reflecting panel 10 of the electromagnetic wave reflecting device 60A includes at least one of a specular reflecting surface and an artificial reflecting surface whose reflection characteristics are controlled, that is, a metasurface. The metasurface is formed by periodic structures or patterns finer than the wavelength and is designed to reflect radio waves in a desired direction. Specifically, a ground layer is formed on one surface of the dielectric layer, and a periodic pattern designed with a conductive material to have prescribed reflection characteristics is formed on the other surface of the dielectric layer, thereby forming the reflecting surface of the metasurface. The metasurface can reflect electromagnetic waves at a reflection angle different from the incident angle. Reflection at an angle different from the incident angle may also include controlled diffusion and scattering, and including them is called non-specular reflection.

[0034] For example, the structure 20 is a metal cabinet about 1 m in height. When observed from the base station 31, the wireless terminal 34 assembled to the IoT (Internet of Things) sensor is located behind the cabinet. The reflecting panel 10 of the electromagnetic wave reflecting device 60A has a non-specular reflecting surface on at least a part of the reflecting surface 105, and reflects the incident electromagnetic waves at an angle different from the incident angle toward the blind area 30. In the illustrated example, the electromagnetic wave reflecting device 60A reflects the electromagnetic waves incident on the reflecting panel 10 at an angle different from the incident angle downward relative to the incident position. Generally, the metasurface designs fine periodic patterns in such a way as to control the reflection direction in the horizontal plane parallel to the XY plane. However, by designing the periodic patterns in such a way as to control the reflection angle in the vertical (XZ) plane, the Figure 1A above-described reflection structure can be realized. The metasurface can also be designed to reflect vertically incident electromagnetic waves at a reflection angle greater than 0° and less than 90°.

[0035] The electromagnetic wave reflecting device 60A reflects the radio waves from the base station 31 toward the blind area 30 and suppresses the radio waves from escaping outside the production line 3 between the base station 31 and the wireless terminal 34. Through the wireless transmission system 1A, improvement of the radio wave environment and suppression of the radio waves from escaping outside the necessary space are achieved.

[0036] Figure 1B is a schematic diagram of the wireless transmission system 1B. The wireless transmission system 1B includes a base station 31 and an electromagnetic wave reflecting device 60B that reflects electromagnetic waves in the frequency band used by the base station 31. The electromagnetic wave reflecting device 60B has a reflecting panel 10-1 erected substantially perpendicular to the installation surface P and a reflecting panel 10-2 inclined with respect to the installation surface P. As described above, "substantially perpendicular" includes a range of 90° ± 10°. The reflecting panel 10-2 is inclined in the direction of the base station 31 with respect to the perpendicular line of the installation surface P, and its reflecting surface 105 faces obliquely downward.

[0037] The beam cross-section of the electromagnetic wave radiated from the base station 31 hits a position lower than the highest position of the reflecting surface 105 of the electromagnetic wave reflecting device 60B, that is, the highest position of the reflecting surface 105 of the reflecting panel 10-2, and is incident on the reflecting panel 10-2. In the environment where the base station 31 is used, a metal rack with a height of about 1.5 m is placed as the structure 20. When observed from the base station 31, the area behind the rack is the blind area 30, and the wireless terminal 34 is located in this blind area 30.

[0038] The radio wave radiated from the base station 31 is reflected by the reflecting surface 105 of the reflecting panel 10-2 and received by the wireless terminal 34. The reflecting panel 10 of the electromagnetic wave reflecting device 60B has a non-specular reflecting surface on at least a part of the reflecting surface 105, and reflects the incident electromagnetic wave toward the blind area 30 at an angle different from the incident angle. The reflecting surface 105 is formed by a periodic pattern, a mesh pattern, a geometric pattern, etc. formed by a transparent conductive material or a metal material. The size, shape, interval, etc. of the periodic pattern of the non-specular reflecting part in the reflecting surface 105 are designed in a manner to obtain the desired reflection characteristics.

[0039] The electromagnetic wave reflecting device 60B reflects the radio wave from the base station 31 toward the blind area 30 and suppresses the radio wave from escaping outside the production line 3 between the base station 31 and the wireless terminal 34. Through the wireless transmission system 1B, the improvement of the radio wave environment and the suppression of the radio wave from escaping outside the necessary space are achieved.

[0040] Figure 1C It is a schematic diagram of the wireless transmission system 1C. The wireless transmission system 1C includes a base station 31 and an electromagnetic wave reflecting device 60C that reflects the electromagnetic wave of the frequency band used by the base station 31. The electromagnetic wave reflecting device 60C has a reflecting panel 10-1 that stands substantially perpendicular to the installation surface P and a reflecting panel 10C-2 that is inclined with respect to the installation surface P.

[0041] The beam cross-section of the electromagnetic wave radiated from the base station 31 hits a position lower than the highest position of the reflecting surface 105 of the electromagnetic wave reflecting device 60C, that is, the highest position of the reflecting surface 105C of the reflecting panel 10C-2, and is incident on the reflecting panel 10C-2. In the environment where the base station 31 is used, a metal rack with a height of about 1.5 m is placed as the structure 20. When observed from the base station 31, the area behind the rack is the blind area 30, and the wireless terminal 34 is located in this blind area 30.

[0042] In Figure 1CIn the example, the specular reflection of the electromagnetic wave reflection device 60C is utilized. The radio wave radiated from the base station 31 is specularly reflected by the reflection surface 105C of the reflection panel 10C-2 and is incident on the reflection panel 10-1. The incident wave is reflected by the reflection panel 10-1 toward the blind zone 30 and is received by the wireless terminal 34. Generally, a specular reflection surface can achieve a reflection efficiency close to 100%, and the reflected wave reflected by the reflection panel 10C-2 also has sufficient reflection intensity. The reflected wave reflected again by the reflection panel 10-1 is also received by the wireless terminal 34 with sufficient power.

[0043] The electromagnetic wave reflection device 60C reflects the radio wave from the base station 31 toward the blind zone 30 and suppresses the radio wave from escaping outside the production line 3 between the base station 31 and the wireless terminal 34. Through the wireless transmission system 1C, improvement of the radio wave environment and suppression of the radio wave from escaping outside the necessary space are achieved.

[0044] <Electromagnetic Wave Reflection Device and Electromagnetic Wave Reflection Fence>

[0045] Figure 2 is a schematic diagram of the electromagnetic wave reflection device 60. The electromagnetic wave reflection device includes a reflection panel 10 and a frame 50 that holds the reflection panel. The width or lateral direction of the reflection panel 10 is set as the X direction, the thickness direction is set as the Y direction, and the height or longitudinal direction is set as the Z direction. The frame 50 holds both ends along the height direction of the reflection panel 10. The frame 50 not only stably holds both ends of the reflection panel 10 but also contributes to the safety of the conveyance of the reflection panel 10 and the enhancement of mechanical strength. In addition, when a plurality of reflection panels 10 are connected and used, the frame 50 may also have a function and structure for electrically connecting between adjacent reflection panels 10 and making the reflection potential continuous.

[0046] The electromagnetic wave reflection device 60 may also have a top frame 57 that holds the upper end in the height direction of the reflection panel 10 and a bottom frame 58 that holds the lower end. The frame 50 may also be referred to as a side frame according to the positional relationship with the top frame 57 and the bottom frame 58. Legs 56 may also be provided on the electromagnetic wave reflection device 60 to make the electromagnetic wave reflection device 60 stand on its own.

[0047] The reflection panel 10 reflects electromagnetic waves in a specified frequency band selected from frequencies of 1 GHz or higher and 300 GHz or lower. The reflection surface 105 of the reflection panel 10 has at least one of a non-specular reflection surface and a specular reflection surface including a metasurface. The reflection surface 105 is formed by a periodic pattern, a mesh pattern, a geometric pattern, etc. formed of a transparent conductive material, a metal material of a good conductor. In the case where a metasurface is formed by a periodic conductive pattern, it is patterned in such a way as to obtain desired reflection characteristics.

[0048] Figure 3It is a schematic diagram of the electromagnetic wave reflection fence 100. The electromagnetic wave reflection fence 100 is formed by connecting a plurality of electromagnetic wave reflection devices 60-1, 60-2, and 60-3. The reflection panels 10-1, 10-2, and 10-3 of the electromagnetic wave reflection devices 60-1, 60-2, and 60-3 (hereinafter, appropriately collectively referred to as "electromagnetic wave reflection device 60") are connected by a frame 50. The number of the connected electromagnetic wave reflection devices 60 is appropriately determined according to the installation environment.

[0049] From the viewpoint of maintaining the continuity of the reflection potential, it is sometimes preferable that the reflection panels 10-1, 10-2, 10-3 (hereinafter, appropriately collectively referred to as "reflection panel 10") are electrically connected to each other. In the case where the reflecting surface 105 includes a metasurface, the adjacent reflection panels 10 may not be electrically connected. A top frame 57 and a bottom frame 58 may also be provided at the upper and lower ends of each reflection panel 10.

[0050] In the case where legs 56 are provided on each electromagnetic wave reflection device 60, it may be configured to be able to fix the legs 56 to the installation surface using screws, bolts, etc. Alternatively, a component such as a caster may be installed on the legs 56 to make it movable. The electromagnetic wave reflection fence 100 and a single electromagnetic wave reflection device 60 may also be used in combination.

[0051] Figure 4 It is a schematic diagram of the electromagnetic wave reflection fence 100A as a modified example. The electromagnetic wave reflection fence 100A is formed by connecting the electromagnetic wave reflection devices 60A-1, 60A-2, and 60A-3. The electromagnetic wave reflection device 60A-1 and 60A-2 are connected in the same direction (in this example, the X direction) by a frame 50A, and the electromagnetic wave reflection device 60A-2 and 60A-3 are connected in different directions by a frame 50A. The upper and lower ends of the reflection panels 10A-1, 10A-2, and 10A-3 of the electromagnetic wave reflection devices 60A-1, 60A-2, and 60A-3 (hereinafter, appropriately collectively referred to as "reflection panel 10A") may also be held by a top frame 57 and a bottom frame 58, respectively.

[0052] Figure 5 It is along the frame 50A Figure 4Configuration example of the horizontal cross-section of the A-A line. This horizontal cross-section is a cross-section within a plane parallel to the XY plane where the electromagnetic wave reflection fence 100A is provided. The frame 50A has a main body 505 formed of a conductor such as aluminum, and slits 551a, 551b, 551c, and 551d (hereinafter, collectively referred to as "slits 551" as appropriate) formed in the main body 505. The reflection panels 10A-1 and 10A-2 are respectively inserted and held in the opposing slits 551a and 551b of the frame 50A. In order to make the frame 50A lighter, a certain space is formed between each slit 551 and the central portion of the main body 505. In the case of further weight reduction, a cavity can also be provided in the central portion of the main body 505. Having Figure 5 The frame 50A having the horizontal cross-sectional shape can be formed, for example, by injection molding.

[0053] The outer shape of the horizontal cross-section of the frame 50A is substantially square. By processing it into a shape that is substantially symmetric with respect to the center of the main body 505, the frame 50A can be used in any orientation. The width w1 corresponding to the length of one side of the horizontal cross-section of the frame 50A is, for example, 40 mm to 60 mm. The width w2 of the slits 551a to 551d is determined according to the thickness of the reflection panel 10A used. The thickness w3 of the central portion of the main body 505 is set in the range of 15 mm to 35 mm according to the strength required for the frame 50A. The outer surface of the frame 50A can also be covered with an insulating cover such as resin.

[0054] Figure 6 is Figure 4 Top view of the connecting portion C. The reflection panels 10A-2 and 10A-3 are held and connected to the adjacent slits 551a and 551c of the frame 50A. By selecting appropriate slits 551, the reflection panels 10A can be connected in two directions. As Figure 4 shown, the reflection panels 10A-1 and 10A-2 can also be connected in the X direction, and the reflection panel 10A-3 can be connected in the -Y direction. Another reflection panel 10A can also be further connected to the reflection panel 10A-3 in the -Y direction or -X direction. Thus, a prescribed space can be surrounded, and the leakage of radio waves can be effectively suppressed.

[0055] Figure 7 is a diagram showing another connection example of the electromagnetic wave reflection fence. The reflection panels 10A-2 and 10A-3 are connected by a frame 50B having a triangular horizontal cross-sectional shape. By selecting two of the slits 551a, 551b, and 551c and connecting the reflection panels 10A, the reflection panels 10A can be connected in two directions other than at a right angle. According to the environment in which the electromagnetic wave reflection fence is used and the positional relationship with respect to the base station 31 and the structure 20, a plurality of electromagnetic wave reflection devices 60 can be connected at an angle other than parallel. The triangular frame 50B can also connect the reflection panel 10C-2 toFigure 1C It is used when reaching the upper end of the reflection panel 10-1.

[0056] Figure 8 It shows a connection example of the electromagnetic wave reflection fence 300. The electromagnetic wave reflection fence 300 has two sets of electromagnetic wave reflection fences 100-1 and 100-2 arranged parallel or non-parallel to each other, and a top panel 110 covering the upper parts of the electromagnetic wave reflection fences 100-1 and 100-2. In this example, the top panel 110 is combined with the electromagnetic wave reflection fences 100-1 and 100-2 formed by connecting two or more electromagnetic wave reflection devices 60, but it is also possible to combine the top panel 110 with a structure in which individual electromagnetic wave reflection devices 60 are arranged parallel or non-parallel to each other, or a structure in which the electromagnetic wave reflection device 60 and the electromagnetic wave reflection fence 100 are opposed to each other. The planar shape of the top panel 110 is determined according to the arrangement direction of the electromagnetic wave reflection fences 100-1 and 100-2. Similar to the reflection panel 10A for the electromagnetic wave reflection fences 100-1 and 100-2, the top panel 110 has a reflection surface that reflects radio waves (for example, in a specified frequency band in the range of 1 GHz or more and 300 GHz or less, or 1 GHz or more and 170 GHz or less) from the base station. The reflection surface has at least one of a specular reflection surface and a non-specular reflection surface including a metasurface.

[0057] In the electromagnetic wave reflection fence 300, the beam cross-section of the electromagnetic wave radiated from the base station enters the reflection surface of the electromagnetic wave reflection fence 100-1 or 100-2 at a position lower than the uppermost end, or the reflection surface inside the top panel 110, and is reflected downward from the incident position. The surface of the reflection surface of the top panel 110 facing the outside, that is, the upper side, becomes the uppermost end of the reflection surface, and the surface facing the inside, that is, the lower side, becomes the incident surface of the electromagnetic wave. The electromagnetic wave incident on the reflection surface of the electromagnetic wave reflection fence 100-1 or 100-2, or the reflection surface of the top panel 110, is reflected downward from the incident position, suppressing the escape of radio waves outside the electromagnetic wave reflection fence 300. When the electromagnetic wave reflection fence 300 is used outdoors, a protective layer with an ultraviolet protection function can also be provided on the outermost layer of the top panel 110, especially on the surface facing the outside.

[0058] In Figure 8 's example, a rectangular top panel 110 that covers the space between the electromagnetic wave reflection fences 100-1 and 100-2 separated by a specified distance is used. As the top frame 57 that holds the upper end of the reflection panel 10A, Figure 5 and Figure 6The frame 50A shown. The upper end of the reflection panel 10A can also be held by the slit 551a of the frame 50A, and the edge of the top panel 110 can be held by another adjacent slit 551d. By using the top panel 110, the dissipation of radio waves scattered by structures in the space can be effectively suppressed. The top panel 110 is not limited to a flat panel horizontally arranged with respect to the installation surface (XY plane), and may also have an arched curved surface.

[0059] For example, the thickness of the reflection panel of the top panel 110 is 5.0 mm or more and 17.0 mm or less. When there are almost no obstacles exceeding the height of the electromagnetic wave reflection fences 100-1 and 100-2 in the space between the electromagnetic wave reflection fences 100-1 and 100-2, the top panel 110 bent with an appropriate radius of curvature can also be used.

[0060] As another configuration example, a frame 50B having Figure 7 the horizontal cross-sectional shape can also be used for the top frame 57. As shown in Figure 1B , the top panel 110 is connected obliquely with respect to the perpendicular line of the installation surface (XY plane). In this case, the top panel 110 extends obliquely upward from the upper end of the electromagnetic wave reflection fence 100-1 like the reflection panel 10-2 shown in Figure 1B . The front end of the first top panel extending obliquely upward from the upper end of the electromagnetic wave reflection fence 100-1 and the front end of the second top panel extending obliquely upward from the upper end of the electromagnetic wave reflection fence 100-2 can also be connected by the frame 50B to form a tunnel.

[0061] Figure 9 is a plan schematic diagram showing another arrangement example of the electromagnetic wave reflection fences. The electromagnetic wave reflection fences 100-1 and 100-2 are arranged non-parallel to the production line 3. The electromagnetic wave reflection fences 100-1 and 100-2 can be arranged in an appropriate orientation according to the arrangement of the production machinery inside the production line 3, the movement range, the arrangement of the structure 20 (refer to Figures 1A to 1C ) that becomes an obstacle, the position of the base station 31, etc. The number of connected electromagnetic wave reflection devices 60 can also be appropriately selected according to the width of the production line 3. When the position of the transmitting antenna of the base station 31 is higher than the uppermost end of the electromagnetic wave reflection device 60, the height of the electromagnetic wave reflection fences 100-1 and 100-2 can be selected in such a way that the beam cross-section (3 dB beam width) of the electromagnetic wave radiated from the base station 31 is incident on a position below the highest position of the effective reflection surface of the reflection panel of the electromagnetic wave reflection device 60. As shown in Figure 8 , a top panel 110 can also be provided between the electromagnetic wave reflection fences 100-1 and 100-2 to cover the space of the production line 3.

[0062] In the case where the top panel 110 is provided, the electromagnetic wave radiated from the base station 31 is incident obliquely from below on the reflection surface on the inner side of the top panel 110 and is reflected toward the space between the electromagnetic wave reflection fences 100-1 and 100-2. By using the top panel 110, the electric wave radiated from the base station 31 can be effectively reflected inside the production line 3.

[0063] Figure 10 It is a plan schematic diagram showing a configuration example of the electromagnetic wave reflection device 60. The electromagnetic wave reflection device 60 can also be used individually. For example, the electromagnetic wave reflection devices 60-1, 60-2, 60-3, and 60-4 can be used to surround a specified area. Four electromagnetic wave reflection fences 100 can be used instead of the electromagnetic wave reflection devices 60-1 to 60-4. The top panel 110 can be provided to cover the area surrounded by the four electromagnetic wave reflection devices 60 or the electromagnetic wave reflection fences 100. The electromagnetic wave radiated from the base station is incident on the area surrounded by the electromagnetic wave reflection device 60 or the electromagnetic wave reflection fence 100. The electromagnetic wave from the base station is incident on the reflection surface on the inner side of the top panel 110, or at a position lower than the upper end of the reflection surface of the electromagnetic wave reflection device 60 or the electromagnetic wave reflection fence and is reflected downward. Thereby, the electric wave environment inside the production line 3 can be improved, and the leakage of the electric wave outside the production line 3 can be effectively suppressed.

[0064] Using a model in which a base station 31 and an electromagnetic wave reflection device 60 are provided in a facility equipped with a production line 3, the improvement effect of the electric wave environment and the electric wave leakage suppression effect are confirmed. Evaluation is made focusing on the positional relationship between the height of the antenna of the base station 31 and the highest position of the reflection surface 105 of the electromagnetic wave reflection device 60.

[0065] <Example 1>

[0066] Example 1 is Example 1. There are a plurality of structures such as metal racks and production machinery in a facility with a length of 50.0 m, a width of 50.0 m, and a height of 10.0 m. A base station 31 operating at a frequency of 28.2 GHz is introduced into the facility (refer to Figure 1A etc.), and signals are transmitted and received between the wireless terminal 34 assembled to the production machinery and the base station 31. Looking from the antenna of the base station 31, the area behind the structure 20 is a blind spot 30. An electromagnetic wave reflection device 60 using a reflection panel 10 with a width of 1.0 m and a height of 2.0 m is provided at a position where the electric wave from the base station 31 can be reflected toward the blind spot 30. The top frame 57 and the bottom frame are not used, the height of the lower end of the reflection panel 10 from the installation surface is 0.15 m, and the height of the upper end of the reflection surface 105 is 2.50 m.

[0067] The position of the antenna of base station 31 is 3.0 m from the floor, and the maximum gain is 20 dBi. Base station 31 transmits a beam with a half-value width of 8° in the vertical direction and 40° in the horizontal direction obliquely downward. The beam cross-section of the electromagnetic wave emitted from base station 31 hits a position lower than the uppermost end of the reflecting surface 105 of the electromagnetic wave reflecting device 60 and is reflected downward to the blind area 30. The received power of the blind area 30 before the electromagnetic wave reflecting device 60 is set is -100.0 dBm. By setting the electromagnetic wave reflecting device 60, the received power of the blind area 30 changes to -85.0 dBm, an improvement of 15.0 dB. On the other hand, outside production line 3, the received power before the electromagnetic wave reflecting device 60 is set is -125.0 dBm, and the received power after setting is -125.0 dBm, showing no change.

[0068] It was confirmed that: by introducing the electromagnetic wave reflecting device 60, the radio wave environment in the blind area 30 within production line 3 is improved, and the dissipation of radio waves to the outside of production line 3 is suppressed.

[0069] <Example 2>

[0070] Example 2 is Embodiment 2. In Example 2, the Figure 8 shown tunnel-shaped electromagnetic wave reflecting fence 300 is used. There are multiple structures such as metal racks and production machinery in a facility with a length of 50.0 m, a width of 50.0 m, and a height of 10.0 m. A base station 31 (refer to Figure 1A etc.) operating at a frequency of 28.2 GHz is introduced into the facility, and signals are transmitted and received between a wireless terminal 34 assembled on the production machinery and base station 31. From the perspective of the antenna of base station 31, the area behind structure 20 is the blind area 30. An electromagnetic wave reflecting fence 300 formed by connecting electromagnetic wave reflecting devices 60 in a tunnel shape is constructed at a position where the radio waves from base station 31 can be reflected toward the blind area 30.

[0071] Four electromagnetic wave reflecting devices 60 using reflection panels 10 with a width of 1.0 m and a height of 2.0 m are set, and they are connected by a frame 50 to fabricate an electromagnetic wave reflecting fence 100-1. Similarly, four electromagnetic wave reflecting devices 60 using reflection panels 10 with a width of 1.0 m and a height of 2.0 m are set, and they are connected by a frame 50 to fabricate an electromagnetic wave reflecting fence 100-2. In production line 3, the electromagnetic wave reflecting fences 100-1 and 100-2 are set at an interval of 1 m, and a top panel 110 is set. When the top panel 110 is connected using a frame 50A, the upper ends of the reflection panels 10 used in the electromagnetic wave reflecting fence 100 are hidden inside the frame 50A by about a few millimeters, but such a change in the position of the upper end of the reflecting surface 105 can be ignored.

[0072] The position of the antenna of base station 31 is 1.5 m from the floor, and the maximum gain is 20 dBi. Base station 31 transmits a beam with a half-power beamwidth of 8° in the vertical direction and 40° in the horizontal direction. Inside the tunnel-shaped electromagnetic wave reflection fence 300, from the perspective of the antenna of base station 31, the area behind structure 20 is blind area 30. The electromagnetic wave emitted from base station 31 is incident from below onto the reflection surface on the inner side of the top panel 110 and is reflected towards the lower blind area. The received power of blind area 30 before setting the electromagnetic wave reflection fence 300 is -100.0 dBm. By setting the electromagnetic wave reflection fence 300, the received power of blind area 30 changes to -85.0 dBm, with an improvement of 15.0 dB. On the other hand, outside production line 3, the received power before setting the electromagnetic wave reflection device 60 is -125.0 dBm, and the received power after setting is -125.0 dBm, showing no change.

[0073] It was confirmed that: by using the electromagnetic wave reflection fence 300 formed by connecting the electromagnetic wave reflection devices 60, the radio wave environment in blind area 30 inside production line 3 is improved, and the dissipation of radio waves to the outside of production line 3 is suppressed.

[0074] <Example 3>

[0075] Example 3 is a comparative example. In Example 3, the position of the upper limit of the beam emitted from the antenna of base station 31 is higher than the highest position of the reflection surface 105 of the electromagnetic wave reflection device 60. There are multiple structures such as metal racks and production machinery in a facility with a length of 50.0 m, a width of 50.0 m, and a height of 10.0 m. A base station 31 operating at a frequency of 28.2 GHz is introduced into the facility (refer to Figure 1A etc.), and signals are transmitted and received between the wireless terminal 34 assembled on the production machinery and base station 31. From the perspective of the antenna of base station 31, the area behind structure 20 is blind area 30. Near blind area 30, an electromagnetic wave reflection device 60 using a reflection panel 10 with a width of 1.0 m and a height of 2.0 m is set. Without using the top frame 57 and the bottom frame, the height of the lower end of the reflection panel 10 from the installation surface is 0.15 m, and the height of the upper end of the reflection surface 105 is 2.15 m.

[0076] The position of the antenna of base station 31 is 3.0 m from the floor, and the maximum gain is 20 dBi. Base station 31 transmits a beam with a half-power beam width of 8° in the vertical direction and 40° in the horizontal direction obliquely downward, but the upper limit position of the beam cross-section exceeds the upper end of the electromagnetic wave reflection device 60. The received power of the blind area 30 before the electromagnetic wave reflection device 60 is set is -100.0 dBm. By setting the electromagnetic wave reflection device 60, the received power of the blind area 30 changes to -85.0 dBm, an improvement of 15.0 dB. On the other hand, outside production line 3, the received power before the electromagnetic wave reflection device 60 is set is -125.0 dBm, and the received power after setting changes to -90.0 dBm. This indicates that the radio waves of base station 31 leak outside production line 3.

[0077] Based on the results of Examples 1 to 3, by setting the electromagnetic wave reflection device 60 in such a way that the beam cross-section of the 3 dB beam width of the electromagnetic wave radiated from the antenna of base station 31 hits a position lower than the upper end of the reflection surface of the electromagnetic wave reflection device 60, the radio wave environment of the blind area 30 can be improved, and the leakage of radio waves to the space outside the necessary radio space can be suppressed. It is also possible to connect the reflection panels 10 of the electromagnetic wave reflection device 60 in the height direction according to the installation position of base station 31 to adjust the height. For example, it is also possible to connect three reflection panels with a horizontal length of 2.0 m and a vertical length of 1.0 m in the height direction to make an electromagnetic wave reflection device 60 with a height of 3.0 m.

[0078] The wireless transmission systems 1A to 1C of the embodiment can take both reducing the blind area 30 or improving the radio wave environment and suppressing the leakage of radio waves to the target space by making the electromagnetic waves emitted from the antenna of base station 31 incident on a position lower than the upper end of the reflection surface of the electromagnetic wave reflection device and reflecting them downward from the incident position. The wireless transmission systems 1A to 1C of the embodiment are all applicable to areas extending in a specified direction such as indoor and outdoor event venues, general roads, highways, railway lines, tunnels, etc., in addition to production lines. In addition, it can also be applied to electronic toll collection systems, streets, roundabouts, terraces of commercial facilities or public facilities, arcades, etc.

[0079] The size of the reflection panel 10 used in the electromagnetic wave reflection device 60 can be appropriately designed according to the application scenario. As an example, a size of 10 cm × 10 cm to 4.0 m × 4.0 m can also be used. The height of the antenna of base station 31 only needs to be at a position lower than the uppermost end of the reflection surface 105 of the electromagnetic wave reflection device 60. The height, orientation, and assembly method of the electromagnetic wave reflection device 60 are appropriately designed according to the position of the transmitting antenna of the base station introduced into the environment where the electromagnetic wave reflection device 60 is placed. The reflection surface 105 of the electromagnetic wave reflection device 60 reflects the incident electromagnetic waves downward from the incident position of the electromagnetic waves. Thereby, the blind area 30 is reduced, and the leakage of radio waves from the specified space is suppressed.

[0080] The embodiments of the present disclosure have been described above, but the present disclosure may include the following configurations.

[0081] (Item 1)

[0082] A wireless transmission system, comprising:

[0083] a base station that performs wireless communication in a specified frequency band selected from frequencies of 1 GHz or higher and 300 GHz or lower; and

[0084] an electromagnetic wave reflection device having a reflection panel that reflects electromagnetic waves in the specified frequency band, the electromagnetic wave reflection device being disposed within the communication area of the base station,

[0085] the electromagnetic waves emitted from the base station hit a position lower than the uppermost position of the reflection surface of the reflection panel,

[0086] and the electromagnetic wave reflection device reflects the electromagnetic waves incident on the reflection panel downward to a position lower than the incident position.

[0087] (Item 2)

[0088] The wireless transmission system according to Item 1,

[0089] wherein the reflection panel has a non-specular reflection surface and reflects the electromagnetic waves incident on the reflection panel downward at an angle different from the incident angle.

[0090] (Item 3)

[0091] The wireless transmission system according to Item 1 or 2,

[0092] wherein the reflection panel has a specular reflection surface and reflects the electromagnetic waves incident on the reflection panel downward at an angle the same as the incident angle.

[0093] (Item 4)

[0094] The wireless transmission system according to Item 1,

[0095] wherein the electromagnetic wave reflection device includes: a first reflection panel that stands substantially perpendicular to the installation surface; and a second reflection panel that is connected to the upper end of the first reflection panel,

[0096] and the second reflection panel is inclined from the perpendicular line of the installation surface.

[0097] (Item 5)

[0098] The wireless transmission system according to Item 4,

[0099] The first reflecting surface of the first reflecting panel and the second reflecting surface of the second reflecting panel have specular reflecting surfaces in at least a part thereof.

[0100] (Item 6)

[0101] The wireless transmission system according to any one of Items 1 to 5 includes:

[0102] At least two of the electromagnetic wave reflecting devices facing each other either parallel or non-parallel; and

[0103] A top panel covering the space between at least two of the electromagnetic wave reflecting devices,

[0104] The electromagnetic waves emitted from the base station are incident on a position lower than the uppermost position of the reflecting surfaces of at least two of the electromagnetic wave reflecting devices, or on the reflecting surface inside the top panel, and are reflected downward from the incident position.

[0105] (Item 7)

[0106] The wireless transmission system according to Item 6,

[0107] The reflecting surface inside the top panel is parallel to the installation surfaces of at least two of the electromagnetic wave reflecting devices.

[0108] (Item 8)

[0109] The wireless transmission system according to Item 6,

[0110] The reflecting surface inside the top panel is inclined with respect to the installation surfaces of at least two of the electromagnetic wave reflecting devices.

[0111] (Item 9)

[0112] The wireless transmission system according to any one of Items 1 to 8,

[0113] Connecting a plurality of the electromagnetic wave reflecting devices to form an electromagnetic wave reflecting fence.

[0114] (Item 10)

[0115] The wireless transmission system according to any one of Items 1 to 8,

[0116] A first electromagnetic wave reflecting fence formed by connecting a plurality of the electromagnetic wave reflecting devices and a second electromagnetic wave reflecting fence formed by connecting a plurality of the electromagnetic wave reflecting devices are arranged either parallel or non-parallel.

[0117] This application claims priority based on Japanese Patent Application No. 2022-210450 filed on December 27, 2022, including the entire contents of these Japanese patent applications.

[0118] Description of Reference Numerals

[0119] 1, 1A... Wireless transmission system; 3... Production line; 10, 10A, 10-1, 10-2, 10-3, 10A-1, 10A-2, 10A-3, 10C-2... Reflective panel; 20... Structure; 31... Base station; 34... Wireless terminal; 50, 50A, 50B... Frame; 57... Top frame; 58... Bottom frame; 60, 60A, 60B, 60C, 60-1, 60-2, 60-3, 60A-1, 60A-2, 60A-3... Electromagnetic wave reflection device; 100, 100A, 100-1, 100-2, 300... Electromagnetic wave reflection fence; 110... Top panel.

Claims

1. A wireless transmission system, characterized in that, Comprising: A base station for wireless communication using a specified frequency band selected from frequencies above 1 GHz and below 300 GHz; and An electromagnetic wave reflection device having a reflection panel for reflecting electromagnetic waves in the specified frequency band, the electromagnetic wave reflection device being disposed within the communication area of the base station, The electromagnetic waves emitted from the base station hit a position lower than the uppermost position on the reflection surface of the reflection panel, and the electromagnetic wave reflection device reflects the electromagnetic waves incident on the reflection panel downward to a position lower than the incident position.

2. The wireless transmission system according to claim 1, wherein: The reflection panel has a non-specular reflection surface and reflects the electromagnetic waves incident on the reflection panel downward at an angle different from the incident angle.

3. The wireless transmission system according to claim 1, wherein: The reflection panel has a specular reflection surface and reflects the electromagnetic waves incident on the reflection panel downward at the same angle as the incident angle.

4. The wireless transmission system according to claim 1, wherein: The electromagnetic wave reflection device has: a first reflection panel standing substantially perpendicular to the installation surface; and a second reflection panel connected to the upper end of the first reflection panel, The second reflection panel is inclined from the perpendicular line of the installation surface.

5. The wireless transmission system according to claim 4, wherein: At least a part of the first reflection surface of the first reflection panel and the second reflection surface of the second reflection panel has a specular reflection surface.

6. The wireless transmission system according to claim 1, characterized in that, Comprising: At least two of the electromagnetic wave reflection devices opposed to each other in parallel or non-parallel; and A top panel covering the space between at least two of the electromagnetic wave reflection devices, The electromagnetic waves emitted from the base station are incident on a position lower than the uppermost position on the reflection surface of at least two of the electromagnetic wave reflection devices, or on the inner reflection surface of the top panel, and are reflected downward to a position lower than the incident position.

7. The wireless transmission system according to claim 6, wherein: The inner reflection surface of the top panel is parallel to the installation surface of at least two of the electromagnetic wave reflection devices.

8. The wireless transmission system according to claim 6, wherein: The inner reflection surface of the top panel is inclined with respect to the installation surface of at least two of the electromagnetic wave reflection devices.

9. The wireless transmission system according to any one of claims 1 to 8, wherein: A plurality of the electromagnetic wave reflection devices are connected to form an electromagnetic wave reflection fence.

10. The wireless transmission system according to any one of claims 1 to 8, wherein: A first electromagnetic wave reflection fence formed by connecting a plurality of the electromagnetic wave reflection devices and a second electromagnetic wave reflection fence formed by connecting a plurality of the electromagnetic wave reflection devices are arranged in parallel or non-parallel.

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