Reflection structure and radio communication system

Abstract

One of the purposes of this disclosure is to provide a radio wave reflection structure that can be installed without providing an additional installation place, and a radio communication system for which this reflection structure is used. This reflection structure comprises: a structure that can be used as a social infrastructure; and a radio wave reflector that is incorporated into the structure and causes partial transmission of radio waves.

Description

Reflection Structure and Wireless Communication System

[0001] The present disclosure relates to a reflection structure that reflects radio waves and a wireless communication system using the reflection structure.

[0002] When there is a dead zone where radio waves from a transmitter cannot reach directly due to buildings such as buildings or terrain, the visibility can be improved by installing a reflection structure (also called a reflector) around such a zone (see Non-Patent Document 1).

[0003] Maruyama Tamami, Furuno Tatsuo, Uehayashi Shinji, "Research on Directional Control Reflector for Eliminating Radio Wave Dead Zones", NTT DOCOMO Technical Journal Vol. 17 No. 3, pp. 70-73, Oct. 2009.

[0004] However, generally, in order to newly install a reflection structure, it is necessary to secure an installation location, and land costs, installation work costs, etc. associated with the installation location are incurred.

[0005] An object of the present disclosure is to provide a radio wave reflection structure that can be installed without newly securing an installation location and a wireless communication system using the reflection structure in order to solve the above problems.

[0006] An aspect of the present disclosure is preferably a reflection structure including a structure that can be used as social infrastructure and a radio wave reflector incorporated in the structure that causes partial transmission of radio waves.

[0007] In the reflection structure of the present disclosure, a radio wave reflector is incorporated in a structure used as social infrastructure. Since the reflection structure can be replaced with an existing structure, it can be installed without newly securing an installation location.

[0008] This is an example of the configuration of a wireless communication system using a reflective structure according to Embodiment 1. This is a top view of a reflective structure usable as a tactile paving block according to Embodiment 1. This is a top view of a reflective structure usable as a tactile paving block according to Embodiment 1. This is a diagram showing a first example of incorporating a reflector according to Embodiment 1. This is a diagram showing a second example of incorporating a reflector according to Embodiment 1. This is a diagram showing a third example of incorporating a reflector according to Embodiment 1. This is a diagram showing a fourth example of incorporating a reflector according to Embodiment 1. This is a diagram showing a fifth example of incorporating a reflector according to Embodiment 1. This is a diagram showing a sixth example of incorporating a reflector according to Embodiment 1. This is a first example of a reflective structure whose reflection direction can be controlled according to Embodiment 2. This is a second example of a reflective structure whose reflection direction can be controlled according to Embodiment 2.

[0009] Embodiments of this disclosure will be described with reference to the drawings. The same or corresponding components will be denoted by the same reference numerals, and repetition of the description may be omitted.

[0010] Embodiment 1 Figure 1 shows an example of the configuration of a wireless communication system 200 using a reflective structure 100 according to Embodiment 1. The reflective structure 100 is installed in multiple locations such as the top of a mountain 30, the rooftop and exterior wall of a building 40, and the road surface. Radio waves 50 from the transmitter 10 are reflected by one or more reflective structures 100 and relayed to the receiver 20.

[0011] In the reflective structure 100, a reflector 110 for radio waves 50 is incorporated into a structure that can be used as social infrastructure, such as tactile paving blocks, signs, traffic lights, and building exteriors. Because the reflective structure 100 can be used as social infrastructure, it can replace existing structures and can be installed without securing a new installation location.

[0012] The reflector 110 is, for example, a metal or a dielectric, but is not limited to any material that can reflect radio waves 50. The reflector 110 is partially transparent to the radio waves 50.

[0013] Figure 2 is a top view of a reflective structure 100 that can be used as a tactile paving block. To enable its use as a tactile paving block, the reflective structure 100 comprises a base 120 and a plurality of tactile projections 130 provided on the base 120. As shown in Figure 2, the projections 130 are rectangular in top view and are repeatedly arranged in a one-dimensional direction. Alternatively, as shown in Figure 3, circular projections 130 may be repeatedly arranged in a two-dimensional direction in top view. The shape and arrangement of the projections 130 are not limited to these.

[0014] The reflector 110 may be incorporated into the base 120 or into the projection 130. Below, examples of how the reflector 110 is incorporated into the reflective structure 100 that functions as a tactile paving block will be explained using Figures 4 to 9. Note that Figures 4 to 9 are side views of the reflective structure 100.

[0015] Figure 4 shows the first example of the assembly. A plate-shaped reflector 110 is embedded in each of the protrusions 130. By embedding the reflectors 110 in the protrusions 130, the deterioration of the reflectors 110 can be suppressed.

[0016] The radio wave reflecting surfaces of each reflector 110 are tilted in the same direction. This allows incoming radio waves 50 to be reflected in one direction.

[0017] Furthermore, the inclination of the reflector 110 may be adjusted so that radio waves 50 arriving from a specific direction are reflected in a desired direction. The desired direction is, for example, the direction of a dead zone where radio waves 50 from the transmitter 10 do not easily reach directly. Alternatively, it may be the direction in which the receiver 20 is located. By reflecting the radio waves 50 in these directions, the line of sight in the wireless communication system 200 is improved, and the dead zone is eliminated.

[0018] Figure 5 shows a second example of the assembly. Reflectors 110 are provided on the inner walls of the multiple protrusions 130. This allows for a larger reflection area compared to the first example. The reflectors 110 may also cover the surfaces of the multiple protrusions 130. In this case, since there is no attenuation due to the radio waves 50 passing through the inside of the protrusions 130, the reflection efficiency can be improved compared to the first example. Also, because reflectors 110 are provided on the inner walls of the protrusions 130, the reflection area can be increased compared to the first example.

[0019] Figure 6 shows a third example of the assembly. Inside the multiple protrusions 130, a first reflector 110-1 is provided on the upstream side with respect to the direction of arrival of the radio waves 50, and a second reflector 110-2 is provided on the downstream side. As described above, the reflector 110 is partially transparent to the radio waves 50. In this example, the reflectivity is improved because the radio waves 50 that were not reflected by the first reflector 110-1 can be reflected by the second reflector 110-2.

[0020] Figure 7 shows a fourth example of the assembly. A first reflector 110-1 is provided inside a plurality of protrusions 130. Furthermore, a plate-shaped second reflector 110-2 is provided inside the base 120, extending across the plurality of protrusions 130. By embedding the second reflector 110-2 inside the base 120, the reflective area can be increased compared to the third example.

[0021] Figure 8 shows a fifth example of the assembly. A plate-shaped reflector 110 extending across multiple protrusions 130 is provided inside the base 120. In this example, the radio wave reflecting surface of the reflector 110 is inclined, allowing it to reflect incoming radio waves 50 in one direction.

[0022] Figure 9 shows a sixth example of the assembly. A plate-shaped reflector 110 extending across multiple protrusions 130 is provided inside the base 120. In this example, the radio wave reflecting surface of the reflector 110 is curved in a wave-like manner, which allows for a larger reflecting area compared to the fifth example. Furthermore, the direction of reflection of the radio waves 50 can be controlled by devising the curvature of the radio wave reflecting surface.

[0023] Note that the examples of how the reflectors 110 are incorporated are not limited to those shown in Figures 4 to 9. For example, the reflectors 110 in Figure 4 do not necessarily have to be tilted in the same direction. By tilting each reflector 110 in different directions, it is possible to achieve the effect of reflecting radio waves 50 in multiple directions.

[0024] As described above, in the reflective structure 100 of this disclosure, a reflector 110 for radio waves 50 is incorporated into a structure used as social infrastructure. Since the reflective structure 100 can replace existing structures, it can be installed without securing a new installation location.

[0025] A typical example of a social infrastructure structure is tactile paving. However, the structures of this disclosure are not limited to tactile paving. The same effects can be obtained when the structure is a sign, traffic light, the exterior wall of a building 40, etc. This is common to all the embodiments described below.

[0026] Embodiment 2 In this embodiment, multiple reflective structures 100 with controllable reflection direction will be described. Figures 10 and 11 are side views of the reflective structures 100. The following sections will describe the changes from Embodiment 1.

[0027] Figure 10 shows a first example of a reflective structure 100 whose reflection direction can be controlled. Similar to Figure 6 of Embodiment 1, a first reflector 110-1 is provided on the upstream side with respect to the direction of arrival of the radio waves 50 inside the plurality of protrusions 130, and a second reflector 110-2 is provided on the downstream side.

[0028] Furthermore, the distance between the first reflector 110-1 and the second reflector 110-2 gradually changes at a constant rate in a direction parallel to the extension direction of the first reflector 110-1. This allows a phase angle corresponding to the distance to be assigned to the reflected radio waves 50, and the equiphase planes of the radio waves 50 can be aligned so that the radio waves 50 reflected in a specific direction reinforce each other. This makes it possible to control the reflection direction of the radio waves 50.

[0029] If it is difficult to increase the distance between the first reflector 110-1 and the second reflector 110-2, the phase angle imparted to the radio wave 50 may be adjusted by adjusting the refractive index of the first reflector 110-1.

[0030] Figure 11 shows a second example of a reflective structure 100 whose reflection direction can be controlled. Similar to Figure 7 of Embodiment 1, a first reflector 110-1 is provided inside a plurality of protrusions 130. In addition, a plate-shaped second reflector 110-2 is provided inside the base 120, extending across the plurality of protrusions 130. In this embodiment, the size of the radio wave reflective surface of the first reflector 110-1 gradually changes at a constant rate in a direction parallel to the extension direction of the first reflector 110-1. This makes it possible to impart a phase angle to the reflected radio waves 50 according to the size of the reflective surface, and to align the equiphase surfaces of the radio waves 50 so that the radio waves 50 reflected in a specific direction reinforce each other. This makes it possible to control the reflection direction of the radio waves 50.

[0031] In the example in Figure 10, the distance between the first reflector 110-1 and the second reflector 110-2 changes with respect to the direction in which the protrusions 130 are repeated. Also, in the example in Figure 11, the size of the radio wave reflecting surface of the first reflector 110-1 changes with respect to the direction in which the protrusions 130 are repeated. However, in the case of the protrusions 130, which are rectangular in plan view as shown in Figure 2, the direction of change may be the direction in which the protrusions 130 extend.

[0032] The first reflector 110-1 and the second reflector 110-2 may both be provided inside the base 120. For example, a plate-shaped first reflector 110-1 and a second reflector 110-2 extending across a plurality of protrusions 130 are provided inside the base 120, and the first reflector 110-1 is tilted so that the distance between them gradually changes. This provides the same effect as described in Figure 10.

[0033] This disclosure is not limited to the embodiments described above, and various modifications can be made during implementation without departing from its essence. Furthermore, each embodiment and its modifications may be combined as appropriate, and in that case, the combined effects can be obtained.

[0034] <Modification 1> When the reflector 110 is incorporated into a plurality of protrusions 130, the reflector 110 does not need to be incorporated into all of the plurality of protrusions 130, but may be incorporated into some of the target protrusions. This is common to all of the following embodiments.

[0035] 10: Transmitter, 20: Receiver, 30: Mountain, 40: Building, 50: Radio wave, 100: Reflective structure, 110: Reflector, 110-1: First reflector, 110-2: Second reflector, 120: Base, 130: Protrusion, 200: Wireless communication system

Claims

1. A reflective structure comprising: a structure usable as social infrastructure; and a radio wave reflector incorporated into the structure that causes partial transmission of radio waves.

2. The reflective structure according to claim 1, wherein the reflector is embedded within the structure.

3. The reflective structure according to claim 1, wherein the reflector is provided on the surface of the structure.

4. The reflective structure according to claim 1 or 2, wherein the structure is a braille block comprising a base and a plurality of braille projections provided on the upper surface of the base.

5. The reflective structure according to claim 4, wherein the reflector includes a first reflector provided on the upstream side with respect to the direction of arrival of the radio waves and a second reflector provided on the downstream side.

6. The reflective structure according to claim 5, wherein the distance between the first reflector and the second reflector gradually changes at a constant rate in a direction parallel to the first reflector.

7. The reflective structure according to claim 5, wherein there are a plurality of first reflectors, and the size of the radio wave reflecting surface of the first reflectors gradually changes at a constant rate in a direction parallel to the first reflectors.

8. A wireless communication system comprising: a reflective structure according to any one of claims 1 to 7; a transmitter that transmits the radio waves; and a receiver that receives the radio waves, wherein the reflector reflects the radio waves from the transmitter toward the receiver.

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