Reflection system and design method for reflection system

Abstract

This disclosure relates to a reflection system and a design method for a reflection system. This reflection system has a reflection area, which is an area that reflects radio waves, and a transmission area, which is an area that transmits radio waves.

Description

Reflection System and Method for Designing Reflection System

[0001] The present disclosure relates to a reflection system and a method for designing a reflection system.

[0002] In 5G and 6G services, technological development utilizing radio waves in high-frequency bands including millimeter waves is progressing to realize wireless transmission of large-capacity data. On the other hand, since radio waves in high-frequency bands have strong straightness, there is a problem that transmission quality is significantly degraded in environments with poor line-of-sight.

[0003] As a method for solving this problem, a method of introducing an electromagnetic wave control device capable of changing the reflection direction of radio waves has been studied. As an electromagnetic wave control device, for example, RIS (Reconfigurable Intelligent Surface) is known. For example, Non-Patent Document 1 comprehensively discloses the latest research trends using RIS.

[0004] As an electromagnetic wave control device other than RIS, a metasurface reflector is known. A metasurface reflector is a reflector that fixedly reflects radio waves in an arbitrary direction with respect to an incident angle. For example, Non-Patent Document 2 discloses a technique for realizing retroreflection using a two-layer metasurface reflector.

[0005] Liu, Yuanwei, et al. "Reconfigurable intelligent surfaces: Principles and opportunities." IEEE communications surveys & tutorials, 2021, Vol.23, No.3, p1546-1577Arbabi, Amir, et al. "Planar metasurface retroreflector." Nature Photonics, June 19, 2017, Vol.11, p415-420.

[0006] As mentioned above, metasurface reflectors fixedly reflect radio waves in any direction relative to the angle of incidence. Therefore, a reflection system in which a metasurface reflector is installed on a metal sign, for example, will reflect all radio waves. As a result, radio waves used for wireless communication will not reach the back of the reflection system. In other words, there was a problem in that the wireless communication system, including the reflection system, could not cover the area behind the reflection system.

[0007] The primary objective of this disclosure is to provide a reflective system in which a wireless communication system including the reflective system can cover the area behind the reflective system, in order to solve the aforementioned problems.

[0008] A first aspect of this disclosure is preferably a reflection system having a reflection region which is a region that reflects radio waves and a transmission region which is a region that transmits radio waves.

[0009] A second aspect of this disclosure is a method for designing a reflection system that causes radio waves emitted by a transmitter to reach a receiver by reflecting the radio waves, wherein the reflection system is composed of a transmissive metasurface reflector placed on a diffraction grating, the transmissive metasurface reflector is a reflector that reflects a portion of the radio waves and transmits a portion of them, and the method for designing a reflection system preferably comprises: calculating the area of ​​the transmissive metasurface reflector placed on the diffraction grating so that the phases of the incident radio waves are aligned; cutting the transmissive metasurface reflector to match the area; and placing the cut transmissive metasurface reflector on the diffraction grating.

[0010] According to an aspect of this disclosure, a wireless communication system including a reflective system can cover the area behind the reflective system.

[0011] This figure shows an example configuration of a design system according to Embodiment 1 of this disclosure. This figure shows the hardware configuration of a design device according to Embodiment 1 of this disclosure. This figure shows an example configuration of a reflection system according to Embodiment 1 of this disclosure. This figure shows the angle of incidence and the angle of reflection in a reflector. This figure shows an example configuration of a design system according to a comparative example. This figure shows the angle of incidence and the angle of reflection in a metasurface reflector. This figure shows an example configuration of a reflection system according to Embodiment 2 of this disclosure. This figure shows an example configuration of a reflection system according to Embodiment 3 of this disclosure. This figure shows an example configuration of a reflection system according to Embodiment 4 of this disclosure. This figure shows the first and second configuration examples of a reflection system according to Embodiment 5 of this disclosure. This is a side view showing the first, second and third configuration examples of a reflection system according to Embodiment 5 of this disclosure. This is the first figure showing the coverage area by the third configuration example of the reflection system according to Embodiment 5 of this disclosure. This is the second figure showing the coverage area by the third configuration example of the reflection system according to Embodiment 5 of this disclosure. This figure shows the coverage area by a reflection system according to a comparative example. This is a perspective view showing an example configuration of a reflection system according to Embodiment 6 of this disclosure. This is a perspective view showing an example configuration of a reflection system according to a comparative example.

[0012] The design system and other related components described herein will be explained with reference to the drawings. The same or corresponding components will be denoted by the same reference numerals, and repetition of the explanation may be omitted.

[0013] Embodiment 1 Figure 1 is a diagram showing an example configuration of a design system according to Embodiment 1 of the present disclosure. The design system 100 includes a transmitter 4. The transmitter 4 transmits radio waves. The transmitter 4 is, for example, a base station. The radio waves transmitted from the transmitter 4 are reflected by the reflection system 8a and reach the receiver 6a. The radio waves transmitted from the transmitter 4 also pass through the reflection system 8a and reach the receiver 6b.

[0014] The reflection system 8a is a system that has both a reflection region, which is a region that reflects radio waves, and a transmission region, which is a region that transmits radio waves. The reflection system 8a is, for example, a sign installed in the wireless communication path between the transmitter 4 and the receiver 6. Details of the reflection system 8a will be described later.

[0015] The design system 100 also includes a design device 2. The design device 2 designs the reflection system 8a. The design of the reflection system 8a is performed by determining the design pattern to be used.

[0016] Figure 2 shows the hardware configuration of a design apparatus according to Embodiment 1 of the present disclosure. Each function of the design apparatus 2 may be partially or entirely composed of hardware such as a PLD (Programmable Logic Device) or FPGA (Field Programmable Gate Array), or it may be composed of a program executed by a processor such as a CPU.

[0017] For example, design device 2 can be implemented using a computer and a program, and the program can be recorded on a storage medium or provided via a network.

[0018] As shown in Figure 2, the design device 2 has an input unit 200, an output unit 201, a communication unit 202, a CPU 203, a memory 204, and an HDD 205 connected via a bus 206, and functions as a computer. The design device 2 is also capable of inputting and outputting data to and from a computer-readable storage medium 207.

[0019] The input unit 200 is, for example, a keyboard and mouse. The output unit 201 is, for example, a display device such as a display.

[0020] The communication unit 202 is, for example, a communication interface that communicates with a wireless device to be controlled.

[0021] The CPU 203 controls each component of the design device 2 and performs predetermined processing. The memory 204 and HDD 205 store data, etc.

[0022] The storage medium 207 is capable of storing programs and the like that which execute the functions of the design device 2. Note that the architecture of the design device 2 is not limited to the example shown in Figure 2.

[0023] Figure 3 shows an example of the configuration of a reflective system according to Embodiment 1 of the present disclosure. The reflective system 8a is configured by forming a through-hole 83 at a specific position on the reflector plate 82. That is, in the reflective system 8a, the reflector plate 82 is the reflective region, and the through-hole 83 is the transmissive region.

[0024] The reflector 82 is a flat device that has the property of naturally reflecting radio waves. The reflector 82 may be, for example, a metal plate or glass coated with metal particles.

[0025] The through-hole 83 is a hole formed to penetrate the reflector 82. The through-hole 83 is formed at a specific location on the reflector 82. The specific location may be, for example, a location that does not impair the design of the sign if the reflective system 8a is a sign. Alternatively, the specific location may be set based on the frequency of the radio waves used in wireless communication.

[0026] Figure 4 shows the angle of incidence and angle of reflection at the reflector. As mentioned above, the reflector 82 is a flat device that has the property of naturally reflecting radio waves. Therefore, the angle of incidence and angle of reflection of the radio waves reflected by the reflector 82 are the same angle θ.

[0027] The effects obtained by the reflective system according to this embodiment will be explained. Figure 5 is a diagram showing an example of the configuration of a design system according to a comparative example. The design system 500 according to the comparative example includes a reflective system 800. The reflective system 800 is a reflective system in which a metasurface reflector 84 is installed on a sign 9 which is a metal body.

[0028] The metasurface reflector 84 is a reflector that fixedly reflects radio waves in any direction relative to the angle of incidence. Radio waves transmitted from the transmitter 4 are reflected by the metasurface reflector 84 and reach the receiver 6a. On the other hand, the radio waves transmitted from the transmitter 4 do not pass through the metasurface reflector 84 and the signboard 9, and therefore do not reach the receiver 6b. Thus, since the radio waves transmitted from the transmitter 4 do not reach the back side of the reflection system 800, there was a problem that the wireless communication system including the reflection system 800 could not cover the area on the back side of the reflection system 800.

[0029] The reflection system 8a according to this embodiment has both a reflection region and a transmission region. That is, radio waves transmitted from the transmitter 4 are not only reflected by the reflection system 8a and reach the receiver 6a, but also pass through the reflection system 8a and reach the receiver 6b. In other words, since the radio waves used in wireless communication reach the back side of the reflection system 8a, the wireless communication system including the reflection system 8a can cover the area on the back side of the reflection system.

[0030] Figure 6 shows the angle of incidence and angle of reflection in the metasurface reflector. As mentioned above, the metasurface reflector 84 is a reflector that fixedly reflects radio waves in any direction with respect to the angle of incidence. Therefore, the angle of incidence θ of the radio waves reflected by the reflector 82 １ and reflection angle θ ２ These will be different angles.

[0031] Embodiment 2 Figure 7 is a diagram showing an example of the configuration of a reflection system according to Embodiment 2 of the present disclosure. The reflection system 8b is configured by forming a transmissive metasurface reflector 86 at a specific position on the reflector 82. That is, in the reflection system 8b, the reflector 82 is the reflection region, and the transmissive metasurface reflector 86 is the transmission region.

[0032] The transmissive metasurface reflector 86 is a reflector that reflects a portion of radio waves and transmits a portion of them. Furthermore, the transmissive metasurface reflector 86 can set the reflection angle and transmission angle of radio waves to any arbitrary angle.

[0033] The transmissive metasurface reflector 86 is configured to penetrate the reflector 82. The transmissive metasurface reflector 86 may be configured to be inserted, for example, into a hole formed to penetrate the reflector 82. The transmissive metasurface reflector 86 is formed at a specific position on the reflector 82. The specific position and the reflection angle of radio waves by the transmissive metasurface reflector 86 may be set based on the position of the transmitter used in wireless communication and the area to be covered on the back side of the reflection system 8b.

[0034] The reflection system 8b according to this embodiment has both a reflection region and a transmission region. That is, the radio waves transmitted from the transmitter 4 not only reach the receiver 6a after being reflected by the reflection system 8b, but also pass through the reflection system 8b to reach the receiver 6a. In other words, since the radio waves used in wireless communication reach the back side of the reflection system, the wireless communication system including the reflection system can cover the area on the back side of the reflection system.

[0035] Embodiment 3 Figure 8 is a diagram showing an example of the configuration of a reflective system according to Embodiment 3 of the present disclosure. The reflective system 8c is configured by forming a transmissive metasurface reflector 86 on the outer circumference of a reflector 82. That is, in the reflective system 8c, the reflector 82 is the reflective region, and the transmissive metasurface reflector 86 is the transmissive region.

[0036] The transmissive metasurface reflector 86 is configured to surround the outer periphery of the reflector 82. The design of the transmissive metasurface reflector 86 or the reflection angle of radio waves by the transmissive metasurface reflector 86 may be set based on the position of the transmitter used in wireless communication and the area to be covered on the back side of the reflection system 8c. The design of the transmissive metasurface reflector 86 may be set, for example, by designing the width or thickness at each position.

[0037] The reflection system 8c according to this embodiment has both a reflection region and a transmission region. That is, the radio waves transmitted from the transmitter 4 are not only reflected by the reflection system 8c and reach the receiver 6a, but also pass through the reflection system 8c and reach the receiver 6b. In other words, since the radio waves used in wireless communication reach the back side of the reflection system, the wireless communication system including the reflection system can cover the area on the back side of the reflection system.

[0038] Embodiment 4 Figure 9 is a diagram showing an example of the configuration of a reflection system according to Embodiment 4 of the present disclosure. The reflection system 8d includes a transmissive metasurface reflector 86. That is, in the reflection system 8d, the region in the transmissive metasurface reflector 86 that reflects radio waves is the reflection region, and the region in the transmissive metasurface reflector 86 that transmits radio waves is the transmission region.

[0039] As described above, the transmissive metasurface reflector 86 is a reflector that reflects a part of radio waves and transmits another part thereof. The design of the transmissive metasurface reflector 86 or the reflection angle of radio waves by the transmissive metasurface reflector 86 may be set based on the position of a transmitter used in wireless communication and an area to be covered on the back side of the reflection system 8d. The design of the transmissive metasurface reflector 86 may be set, for example, by designing the width or thickness thereof.

[0040] The reflection system 8d according to the present embodiment has both a reflection region and a transmission region. That is, radio waves transmitted from the transmitter 4 are not only reflected by the reflection system 8d to reach the receiver 6a, but also pass through the reflection system 8d to reach the receiver 6b. That is, since radio waves used in wireless communication reach the back side of the reflection system, a wireless communication system including the reflection system can cover an area on the back side of the reflection system.

[0041] Embodiment 5 FIG. 10 is a diagram showing first and second configuration examples of a reflection system according to Embodiment 5 of the present disclosure. The reflection system according to the present embodiment is configured by arranging a transmissive metasurface reflector on a diffraction grating. That is, in the reflection systems 8e-1 to 8e-3, the region that reflects radio waves in the transmissive metasurface reflector 86 is a reflection region, and the region that transmits radio waves in the transmissive metasurface reflector 86 is a transmission region.

[0042] FIG. 10 shows reflection systems 8e-1 and 8e-2, which are reflection systems according to the present disclosure. The reflection system 8e-1 is configured of a transmissive metasurface reflector 86a arranged on a diffraction grating. The diffraction grating used in the reflection system 8e-1 is designed based on the distance from the transmitter 4. Region A where the transmissive metasurface reflector 86a is arranged ＋ is calculated based on the phase of an incident wave of the radio wave emitted from the transmitter 4. This setting method will be described later.

[0043] Further, the reflection system 8e-2 is configured of a transmissive metasurface reflector 86b arranged on a diffraction grating having a different design from that of the transmissive metasurface reflector 86a.

[0044] Region 87a is the wave distribution of radio waves incident from the front of the near field of the diffraction grating. Region 87b is the wave distribution of radio waves incident from an oblique direction in the near field of the diffraction grating. As described above, radio waves incident on the diffraction grating exhibit different distributions depending on the incident direction.

[0045] The reflection system according to the present embodiment can limit the phase of incident radio waves within a specific range by setting the arrangement of the transmissive metasurface reflectors on the diffraction grating based on the distance from the transmitter 4. As a result, the reflection system according to the present embodiment can uniform the phase of incident radio waves. Therefore, the reflection system according to the present embodiment can reflect or transmit radio waves in the designed direction without being affected by the distance to the transmitter 4.

[0046] Fig. 11 is a side view showing first, second and third configuration examples of a reflection system according to Embodiment 5 of the present disclosure. A reflection system 8e-3, which is the third configuration example of the reflection system according to the present embodiment, is configured by combining a reflection system 8e-1 and a reflection system 8e-2.

[0047] Referring to Fig. 11, a design method for each reflection system implemented by the design apparatus 2 will be described. First, the design apparatus 2 determines, in the reflection system to be designed, a region A which is a region of the transmissive metasurface reflector 86a to be arranged on the diffraction grating ＋ to be calculated. Region A ＋ is limited within a specific range as shown in Mathematical formula 1 for a point r on the surface of the transmissive metasurface reflector 86a by the phase φ(r) of the incident wave from the wave source that is the source of radio waves, a real constant α and an arbitrary integer n. Note that the wave source herein is the transmitter 4.

[0048]

[0049] The transmissive metasurface reflector 86a is cut according to region A ＋ and arranged on the diffraction grating. As a result, a reflection system 8e-1 capable of uniforming the phase of incident radio waves is formed.

[0050] Here, in the reflection system 8e-2, region A is a region complementary to that of the reflection system 8e-1― It may be formed by placing a transmissive metasurface reflector 86b therein. In this case, region A － It is defined as shown in equation 2.

[0051]

[0052] Figure 12 is a first diagram showing the coverage area of ​​a third configuration example of the reflection system according to Embodiment 5 of the present disclosure. Here, it is shown that the transmissive metasurface reflector 86a is designed to reflect radio waves, and the transmissive metasurface reflector 86b is designed to transmit radio waves.

[0053] In this case, the coverage area of ​​the reflection system 8e-3 is determined by the reflected wave 72 and transmitted wave 73 of the incident wave 71 from the transmitter 4. That is, according to this embodiment, the direction of the radio waves can be divided into two different directions. In particular, according to this embodiment, the direction of the radio waves can be divided into the reflection side and the transmission side of the reflection system.

[0054] Figure 13 is a second diagram showing the coverage area of ​​a third configuration example of the reflection system according to Embodiment 5 of the present disclosure. Here, the case is shown in which both the transmissive metasurface reflector 86a and the transmissive metasurface reflector 86b are designed to reflect radio waves.

[0055] In this case, the coverage area of ​​the reflection system 8e-3 is determined by the reflected waves 72 and 72a of the incident wave 71 from the transmitter 4. That is, according to this embodiment, the direction of the radio waves can be divided into two different directions.

[0056] Figure 14 shows the coverage area of ​​the comparative example reflective system. Here, the coverage area of ​​the comparative example reflective system 800e is shown. The reflective system 800e is composed of a metasurface reflector.

[0057] The incident wave 75 is the incident wave that was assumed during the design of the reflection system 800e. The incident wave 75 is a plane wave. The incident wave 75 is a plane wave because, for example, the wave source is far away. The reflected wave 76 is the reflected wave of the incident wave 75.

[0058] On the other hand, the incident wave 71 is the incident wave from transmitter 4, which is the transmitter that will actually be used. The incident wave 71 is reflected by the reflection system 800e and becomes the reflected wave 78.

[0059] As described above, in the comparative example, with the reflection system 800e, if the incident wave assumed during the design phase changes from the incident wave actually used, the coverage area also changes. In other words, if the position information of the transmitter used changes, there was a problem in that the range could not be covered as designed unless the design of the reflection system 800e was changed.

[0060] The reflection system according to this embodiment is formed by arranging a transmissive metasurface reflector on a diffraction grating in accordance with region A+, which is calculated so that the phase of the incident wave is aligned. Therefore, even if the position information of the transmitter used changes, the reflection system according to this embodiment can cover the range as designed without changing the design of the reflection system.

[0061] Embodiment 6 Figure 15 is a perspective view showing an example of the configuration of a reflective system according to Embodiment 6 of the present disclosure. In the reflective system 8f, the reflector 82 and the transmissive metasurface reflector 86 in the reflective system 8c are joined together, and the boundary of the joint is configured to be saw-toothed. That is, in the reflective system 8e, the reflector 82a is the reflective region, and the transmissive metasurface reflector 86c is the transmissive region.

[0062] Figure 16 is a perspective view showing an example configuration of a reflective system according to a comparative example. The reflective system 8c shown as a comparative example is configured such that the boundary between the reflector 82 and the transmissive metasurface reflector 86 is a plane.

[0063] Edge diffraction occurs on surfaces other than the reflective surfaces of the reflector 82 and the transmissive metasurface reflector 86. In the reflection system 8c, the boundary between adjacent reflectors 82 and transmissive metasurface reflectors 86 is planar, so the effect of edge diffraction is significant. As a result, radio waves reflected by the reflection system 8c form standing waves, and there was a problem in that null points occurred in some locations.

[0064] In the reflection system 8f according to this embodiment, the boundary between the adjacent reflectors 82a and the transmissive metasurface reflector 86c is sawtooth-shaped, so the effect of edge diffraction is small. As a result, radio waves reflected by the reflection system 8f according to this embodiment are less likely to form standing waves, and thus null points are less likely to occur.

[0065] Furthermore, the shape of the boundary between adjacent reflectors 82a and transmissive metasurface reflectors 86c is not limited to a sawtooth shape; any shape that can avoid the formation of null points in certain locations due to the reflected radio waves forming standing waves is acceptable. This boundary shape may be determined, for example, by radio wave propagation simulations based on the frequency of the radio waves used or the sizes of the reflectors 82a and transmissive metasurface reflectors 86c.

[0066] Furthermore, while this disclosure describes an embodiment in which the processing necessary for designing a reflector is performed by a single design device, the embodiments relating to this disclosure are not limited to this. In other words, the design of the reflector relating to this disclosure may be carried out by a design system in which the processing that would normally be performed by design device 2 is divided among multiple devices.

[0067] 4 Transmitter 6 Receiver 6a Receiver 6b Receiver 8 Reflection system 8a Reflection system 8b Reflection system 8c Reflection system 8d Reflection system 8e Reflection system 8e-1 Reflection system 8e-2 Reflection system 8e-3 Reflection system 8e1 Reflection system 8f Reflection system 71 Incident wave 75 Incident wave 82 Reflector 82a Reflector 83 Through hole 84 Metasurface reflector 86 Through-type metasurface reflector 86a Through-type metasurface reflector 86b Through-type metasurface reflector 86c Through-type metasurface reflector 87a Region 87b Region 800 Reflection system 800e Reflection system

Claims

1. A reflective system having a reflective region that reflects radio waves and a transmissive region that transmits radio waves.

2. The reflective system according to claim 1, wherein the reflective region is a reflector which is a flat device having the property of naturally reflecting radio waves, and the transmissive region is a transmissive hole formed at a specific position on the reflector.

3. The reflective system according to claim 1, wherein the reflective region is a reflector which is a flat device having the property of naturally reflecting radio waves, the transmitting region is a transmissive metasurface reflector formed at a specific position on the reflector, and the transmissive metasurface reflector reflects a portion of the radio waves and transmits a portion of them.

4. The reflective system according to claim 1, wherein the reflective region is a reflector which is a flat device having the property of naturally reflecting radio waves, the transmitting region is a transmissive metasurface reflector formed on the outer periphery of the reflector, and the transmissive metasurface reflector reflects a portion of the radio waves and transmits a portion of them.

5. The reflective system according to claim 1, comprising a transmissive metasurface reflector, wherein the reflective region is composed of a region in the transmissive metasurface reflector that reflects radio waves, and the transmissive region is composed of a region in the transmissive metasurface reflector that transmits radio waves.

6. The reflection system according to claim 1, comprising a transmissive metasurface reflector placed on a diffraction grating, the transmissive metasurface reflector, wherein the reflection region is comprised of a region in the transmissive metasurface reflector that reflects radio waves, and the transmission region is comprised of a region in the transmissive metasurface reflector that transmits radio waves.

7. The reflective system according to claim 1, wherein the reflective region is a reflector which is a flat device having the property of naturally reflecting radio waves, the transmitting region is a transmissive metasurface reflector formed on the outer periphery of the reflector, the transmissive metasurface reflector reflects a portion of the radio waves and transmits a portion of them, and the boundary between the reflector and the transmissive metasurface reflector is sawtooth.

8. A method for designing a reflection system that causes radio waves emitted by a transmitter to reach a receiver by reflecting the radio waves, wherein the reflection system is configured by arranging a transmissive metasurface reflector on a diffraction grating, the transmissive metasurface reflector is a reflector that reflects a portion of the radio waves and transmits a portion of them, and the method for designing a reflection system comprising: calculating the area of ​​the transmissive metasurface reflector arranged on the diffraction grating so that the phases of the incident waves of the radio waves are aligned; cutting the transmissive metasurface reflector to match the area; and arranging the cut transmissive metasurface reflector on the diffraction grating.

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