Reflector system, active reflector, and active reflector arrangement method

Abstract

Provided are a reflector system, an active reflector, and an active reflector arrangement method that can efficiently eliminate a dead band region.　The reflector system includes: a first active reflector that has a first reflecting surface at least partially provided in a boundary region located at a boundary portion between a line-of-sight region and a non-line-of-sight region formed by one or more shields for shielding radio waves transmitted by a transmitter and reflects the radio waves transmitted from the transmitter on the first reflecting surface for which the reflection angle can be changed; and a second active reflector that has a second reflecting surface provided in the non-line-of-sight region, or a second reflecting surface at least partially provided in the boundary region and reflects the radio waves transmitted from the transmitter or the radio waves reflected by the first active reflector, on the second reflecting surface for which the reflection angle can be changed.

Description

[Technical Field]

[0001] The present invention relates to a reflector system, an active reflector, and a method for arranging an active reflector. [Background technology]

[0002] Conventionally, there has been a wireless communication system including a phase control reflector that reflects a wireless signal from a wireless base station or a terminal. The wireless communication system includes a first propagation channel information acquisition unit that acquires first propagation channel information between the wireless base station and the phase control reflector, and a second propagation channel information acquisition unit that acquires second propagation channel information between the phase control reflector and the terminal. The phase control reflector controls the phase of the wireless signal reflected toward the terminal or the wireless base station based on the first propagation channel information and the second propagation channel information (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 024611 Summary of the Invention [Problem to be solved by the invention]

[0004] In the environment where the radio base station, terminal, and phase control reflector are installed, there are obstacles that block radio waves such as radio signals, so there are line-of-sight areas that can be seen from the radio base station and non-line-of-sight areas that cannot be seen from the radio base station. In an environment where such line-of-sight areas and non-line-of-sight areas exist, the location of the phase control reflector is an extremely important issue. This is because the degree to which the dead zone where radio waves cannot reach can be eliminated varies greatly depending on the position of the phase control reflector.

[0005] However, in conventional wireless communication systems, the position at which the phase control reflector is disposed is not particularly considered, and there is no particular disclosure about it.

[0006] Therefore, an object of the present invention is to provide a reflector system, an active reflector, and an active reflector arrangement method that can efficiently eliminate dead zones. [Means for solving the problem]

[0007] A reflector system according to an embodiment of the present invention includes a first active reflector having a first reflective surface at least a portion of which is provided within a boundary area located at the boundary between a line-of-sight area and a non-line-of-sight area formed by one or more obstructions that block radio waves transmitted by a transmitter, and which reflects the radio waves transmitted from the transmitter with the first reflective surface, the reflection angle of which is variable; and a second active reflector having a second reflective surface provided within the non-line-of-sight area or at least a portion of which is provided within the boundary area, and which reflects the radio waves transmitted from the transmitter or the radio waves reflected by the first active reflector with the second reflective surface, the reflection angle of which is variable. [Effects of the Invention]

[0008] It is possible to provide a reflector system, an active reflector, and an active reflector arrangement method that can efficiently eliminate dead zones. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a simulation model of region 1. [Figure 2] FIG. 2 is a diagram illustrating a line-of-sight area, a non-line-of-sight area, and a dead zone area. [Figure 3] 1 is a diagram illustrating an example of antenna units 11 and 12 of an antenna set of a wireless base station 10. FIG. [Figure 4] 1 is a diagram showing an example of a reflect array antenna of an active reflector 110. FIG. [Figure 5] 2 is a diagram showing an example of a circuit configuration of an active reflector 110. FIG. [Figure 6] FIG. 10 is a diagram showing the results of a first simulation. [Figure 7] FIG. 10 is a diagram showing the results of a first simulation. [Figure 8] FIG. 10 is a diagram showing the results of a second simulation. [Figure 9] FIG. 10 is a diagram showing the position of the reflecting surface 111 of the active reflector 110 in the third simulation. [Figure 10] FIG. 10 is a diagram showing the results of a third simulation. [Figure 11] FIG. 10 is a diagram showing the results of a fourth simulation. [Figure 12] FIG. 1 is a diagram illustrating a simulation model. [Figure 13] FIG. 1 is a diagram illustrating a simulation model. [Figure 14] FIG. 10 is a diagram showing the results of a fifth simulation. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Embodiment> The following describes embodiments that apply the reflector system, active reflector, and active reflector arrangement method of the present disclosure. In the following, an XYZ coordinate system is defined and described. The direction parallel to the X axis (X direction), the direction parallel to the Y axis (Y direction), and the direction parallel to the Z axis (Z direction) are perpendicular to each other. For ease of explanation, the -Z direction may be referred to as the lower side or bottom, and the +Z direction may be referred to as the upper side or top. A planar view refers to a view from the XY plane. In the following, the length, width, thickness, etc. of each part may be exaggerated to make the configuration easier to understand. Terms such as parallel, right angle, orthogonal, horizontal, vertical, and up and down may be misaligned to the extent that they do not impair the effects of the embodiments.

[0011] <Simulation model of area 1 and reflector system 100> FIG. 1 is a diagram showing a simulation model of an area 1. FIG. 1 shows, as an example, a state in which a reflector system 100 of an embodiment is arranged in the area 1. The reflector system 100 includes, as an example, two active reflectors 110. Each active reflector 110 has a reflective surface 111. One of the two active reflectors 110 is an example of a first active reflector, and the reflective surface 111 of that active reflector is an example of a first reflective surface. The other active reflector 110 is an example of a second active reflector, and the reflective surface 111 of that active reflector is an example of a second reflective surface.

[0012] As an example, area 1 is a rectangular area, and includes a cross-shaped road 2 and buildings 5A to 5D arranged along road 2. Area 1 does not have a ceiling, and nothing other than those described here exists. Buildings 5A to 5D are an example of a shield that blocks radio waves. Road 2 is divided into an intersection 2I, two roads 2X extending from intersection 2I in the ±X direction, and two roads 2Y extending from intersection 2I in the ±Y direction. When intersection 2I, roads 2X, and 2Y are not particularly distinguished, or when intersection 2I and roads 2X and 2Y are all referred to, they are referred to as road 2. Also, as an example, the center of intersection 2I on the ground surface of cross-shaped road 2 is set as the origin of the XYZ coordinates. Road 2 is flat and parallel to the XY plane. Therefore, the Z coordinate of road 2 is Z = 0 at all positions.

[0013] As an example, the buildings 5A to 5D are square in plan view and are arranged to surround the cross-shaped road 2. The buildings 5A to 5D have a sufficient height (for example, about 30 m) and their shape in plan view is uniform up to the rooftops. As an example, the width of the road 2X in the Y direction and the width of the road 2Y in the X direction are 12 m, and the widths of the buildings 5A to 5D in the X and Y directions are 21 m.

[0014] In area 1, one wireless base station 10 and three receivers 21 to 23 are arranged. The wireless base station 10 is an example of a transmitter. As an example, the wireless base station 10 is arranged at the end of road 2X on the -X direction side. The coordinates of the wireless base station 10 are (X, Y, Z) = (-26, 0, 1.5). As an example, the height of the wireless base station 10 is 1.5 m above the ground. As an example, the wireless base station 10 includes an antenna set having a group of antenna units that transmit streams using a distributed MIMO (Multiple Input Multiple Output) method. Details of such an antenna set will be described later, but here, the coordinates of the center of gravity of the group of antenna units will be described as the coordinates of the wireless base station 10.

[0015] Receiver 21 is located at the end of road 2Y on the -Y side, receiver 22 is located at the end of road 2Y on the +Y side, and receiver 23 is located at the end of road 2X on the +X side. The coordinates of receiver 21 are (X, Y, Z) = (0, -26, 1.5), the coordinates of receiver 22 are (X, Y, Z) = (0, 26, 1.5), and the coordinates of receiver 23 are (X, Y, Z) = (26, 0, 1.5). Therefore, receiver 23 is visible from wireless base station 10, but receivers 21 and 23 are obscured by buildings 5B and 5C and are not directly visible. For example, receivers 21 to 23 are 1.5 m above ground, which is the same height as wireless base station 10. When receivers 21 to 23 are not particularly distinguished from one another, they will be referred to as receiver 20.

[0016] The active reflector 110 on the +Y side is attached to the -Y end of the -X side outer wall of building 5A, at a position closest to intersection 2I of road 2Y, and facing wireless base station 10. The active reflector 110 on the -Y side is attached to the +Y end of the -X side outer wall of building 5D, at a position closest to intersection 2I of road 2Y, and facing wireless base station 10. The height of the two active reflectors 110 is, for example, 1.5 m above ground.

[0017] The active reflector 110 is arranged with its reflecting surface 111 facing the wireless base station 10. Here, the reflecting surface 111 facing the wireless base station 10 means that a straight line can be drawn from the reflecting surface 111 to the antenna of the wireless base station 10 without being obstructed by an obstruction such as a building 5. This straight line is the shortest optical path.

[0018] The radio waves emitted from the antenna of the wireless base station 10 are reflected by the outer walls of the buildings 5A to 5D, but dead zones, which are areas where the radio waves do not reach, can occur in locations that are not visible from the wireless base station 10, such as the locations of the receivers 21 and 22. Therefore, to enable reception of radio waves even in locations where dead zones may occur, an active reflector 110 is provided. More specifically, dead zones are areas where the strength of the radio waves is below the level required for reception operations in the receivers 21 and 22.

[0019] <Line-of-sight area, non-line-of-sight area, and blind zone area> Fig. 2 is a diagram illustrating line-of-sight areas, non-line-of-sight areas, and dead zone areas. Fig. 2(A) shows line-of-sight area 30A and non-line-of-sight area 30B, and Fig. 2(B) shows dead zone areas. Fig. 2(A) omits active reflector 110, and Fig. 2(B) shows area 1, road 2, buildings 5A to 5D, dead zone areas, and the distribution of radio wave intensity.

[0020] As shown in FIG. 2A, the line-of-sight area 30A, indicated by dense dots, is the area visible from the antenna of the wireless base station 10 and is a line-of-sight (LOS) area. The non-line-of-sight area 30B, indicated by sparse dots, is the portion of the road 2 excluding the line-of-sight area 30A and is a non-line-of-sight (NLOS) area. The area visible from the antenna of the wireless base station 10 (line-of-sight area 30A) includes the intersection 2I, two roads 2X, and the portions of the two roads 2Y closer to the intersection 2I than the two dashed lines A. The two dashed lines A are located on a straight line connecting the antenna of the wireless base station 10 and the corners of buildings 5B and 5C facing the intersection 2I. The portions of the line-of-sight area 30A closer to the intersection 2I than the two dashed lines A of the two roads 2Y face the outer walls of the buildings 5A and 5D on the -X direction side, Y1 (m) from the corner of the intersection 2I. Y1 is 3.6 m.

[0021] Furthermore, as can be seen from the distribution of radio wave intensity (dBm) shown in FIG. 2(B), dead zones where radio waves radiated from the antenna of the wireless base station 10 do not reach are generated at the ±Y direction edges of the two roads 2Y. The radio waves radiated from the antenna of the wireless base station 10 reach the line-of-sight area 30A directly, but in the non-line-of-sight area 30B, they are reflected by the outer walls of the buildings 5A-5D, etc. Therefore, the non-line-of-sight area 30B is divided into an area where the radio waves reach and a dead zone where the radio waves do not reach. Note that the distribution of radio wave intensity (dBm) shown in FIG. 2(B) represents the distribution at each position on the road 2 when 25 dBm of power is radiated from the antenna of the wireless base station 10.

[0022] <Radio base station 10> 3 is a diagram showing an example of antenna units 11 and 12 of an antenna set of a wireless base station 10. The wireless base station 10 has a main body 10A and antenna units 11 and 12. The antenna units 11 and 12 form an antenna unit group. The antenna units 11 and 12 are arranged, for example, along the Y direction at an interval d to transmit streams using distributed MIMO.

[0023] The antenna units 11 and 12 are devices that transmit and receive radio waves in a high frequency band (for example, 0.3 GHz to 300 GHz) such as microwaves including millimeter waves. The antenna units 11 and 12 are configured to be able to transmit and receive radio waves corresponding to, for example, a fifth generation mobile communication system (so-called 5G), wireless communication standards such as Bluetooth (registered trademark), and wireless LAN (Local Area Network) standards such as IEEE802.11ac. The antenna units 11 and 12 may be configured to be able to transmit and receive electromagnetic waves corresponding to standards other than these, or may be configured to be able to transmit and receive electromagnetic waves of a plurality of different frequencies. Here, a configuration in which the antenna units 11 and 12 transmit and receive radio waves corresponding to the 5G standard will be described as an example. The radio waves emitted from the antenna units 11 and 12 propagate as a single beam by beamforming.

[0024] Although the radio base station 10 has two antenna units 11 and 12, the number of antenna units may be two or more, or may be three or more, to achieve distributed MIMO. For example, distributed MIMO may be achieved by using two or more radio base stations 10 each having one antenna unit.

[0025] In distributed MIMO, multiple antenna units that transmit streams must be installed at a certain distance from each other, and so are installed at an interval d. The height at which antenna units 11 and 12 are installed may be defined as the height from a reference plane (here, the surface of road 2) that is parallel to the horizontal plane. For example, if an antenna unit that emits radio waves outdoors is installed outdoors, the installation height of the antenna unit may be defined as the height from the outdoor ground. As an example, it is assumed here that the height of antenna units 11 and 12 in the Z-axis direction from the surface (ground) of road 2 is set to 1.5 m.

[0026] <Receiver 20> The receiver 20 may be a wireless base station similar to the wireless base station 10, or may be a terminal such as a smartphone or tablet computer of a user who uses 5G communication. When the receiver 20 is a wireless base station, it is preferable that the receiver 20 is capable of communication using distributed MIMO, similar to the wireless base station 10. When the receiver 20 is a wireless base station similar to the wireless base station 10, the coordinates of the center of gravity of the antenna unit group may be set as the coordinates of the receiver 20.

[0027] <Active Reflector 110> 4 is a diagram showing an example of the configuration of the active reflector 110. As an example, the active reflector 110 is a reflectarray antenna having a plurality of reflecting elements 112 arranged in an array (matrix). The plurality of reflecting elements 112 are positioned on a single reflecting surface 111 parallel to the XY plane.

[0028] The reflective elements 112 are rectangular in plan view and are arranged on the surface of an insulating layer or the like (not shown). Such reflective elements 112 can be produced by patterning a metal foil such as copper or aluminum provided on the surface of the insulating layer or the like. The multiple reflective elements 112 are arranged at equal intervals in the X direction and the Y direction, for example.

[0029] Each reflective element 112 has a via 112A extending from the center of the lower surface and penetrating the insulating layer. That is, each reflective element 112 is mushroom-shaped, for example. A PIN (P-Intrinsic-N) diode or a variable capacitor for RF (Radio Frequency) is provided in the via 112A of each reflective element 112. The PIN diode or variable capacitor is provided to make it possible to change electrical characteristics such as the potential or capacitance of the reflective element 112, and is connected to a drive circuit 113, for example. The PIN diode is switched on / off in response to a drive signal output from the drive circuit 113. Furthermore, the variable capacitor has its capacitance switched in response to the drive signal output from the drive circuit 113.

[0030] Fig. 5 is a diagram showing an example of the circuit configuration of the active reflector 110. Fig. 5(A) shows an example circuit in which a variable capacitor 114A is connected between vias 112A of two reflecting elements 112. The capacitance of the variable capacitor 114A is switched by a drive signal output from a drive circuit 113. Fig. 5(A) shows two reflecting elements 112, but the other reflecting elements 112 are also connected in pairs to variable capacitors 114A in the same way.

[0031] 5(B) shows an example circuit in which a PIN diode 114B is connected between vias 112A of two reflecting elements 112. The PIN diode 114B is switched on and off by a drive signal output from a drive circuit 113. Although two reflecting elements 112 are shown in FIG. 5(B), each of the other reflecting elements 112 is also connected to two PIN diodes 114B in the same manner.

[0032] 5(C) shows an example circuit in which PIN diodes 114C are connected in series between vias 112A and ground layers 112B of each reflecting element 112. The PIN diodes 114C are switched on and off by a drive signal output from a drive circuit 113. Although three reflecting elements 112 are shown in FIG. 5(C), the other reflecting elements 112 are also connected to PIN diodes 114C in the same manner.

[0033] The active reflector 110 can change the reflection angle of the beam formed by the reflected waves reflected by all the reflecting elements 112 to a direction other than specular reflection by adjusting the phase when reflecting the incident wave (beam) incident on the adjacent reflecting elements 112 by switching the electrical characteristics of each reflecting element 112 using a driving signal output from the driving circuit 113.

[0034] The reflection angle and period at which active reflector 110 reflects an incident beam can be set by the pattern of a drive signal that drives variable capacitor 114A, PIN diode 114B, or PIN diode 114C connected to each reflecting element 112. As an example, drive circuit 113 may be configured with a microcomputer, data representing the drive signal pattern may be stored in the microcomputer's memory, and drive circuit 113 may drive variable capacitor 114A, PIN diode 114B, or PIN diode 114C based on the data representing the drive signal pattern. Note that while active reflector 110 having reflecting element 112 shown in FIGS. 4 and 5 has been described as an example here, active reflector 110 may have a configuration other than that described here as long as it can reflect a beam transmitted from radio base station 10 in a direction at an arbitrary reflection angle.

[0035] <First Simulation> Figures 6 and 7 show the results of the first simulation. Figure 6(A) shows paths (1) to (3) in which the position of the active reflector 110 is changed in the simulation model of area 1. Figures 6(B), 7(A), and 7(B) show the channel capacities (bit / s / Hz) when the receivers 21 to 23 receive radio waves transmitted from the wireless base station 10 when the position of the active reflector 110 is changed along paths (1), (2), and (3), respectively.

[0036] Here, as an example, the size of the reflecting surface 111 of the active reflector 110 is 300 mm in length and 300 mm in width, and the area is 0.09 m 2 The position of the active reflector 110 is the position of the center of gravity of the reflecting surface 111. The reflection angle of the active reflector 110 is varied in 1 degree increments within a range of ±90 degrees with respect to the normal vector of the reflecting surface 111 when viewed on the XY plane.

[0037] Channel capacity represents the density of signals that can be multiplexed without interference in a propagation channel of a certain frequency. When channel capacity is high, when different information is transmitted by MIMO antennas, the communication speed increases, and when the same information is transmitted by MIMO antennas, the signal-to-noise ratio (SNR) on the receiving side improves. Channel capacity represents an index of communication performance between MIMO antennas.

[0038] Route (1) is a route that changes the position of the active reflector 110 in the X direction from coordinates (X, Y, Z) = (-25, 5, 1.5) to (25, 5, 1.5) with the reflecting surface 111 of the active reflector 110 facing in the -Y direction. On route (1), the active reflector 110 is located within the line-of-sight area 30A.

[0039] Route (2) is a route that changes the position of the active reflector 110 in the Y direction from coordinates (X, Y, Z) = (-5, -25, 1.5) to (-5, 25, 1.5) with the reflecting surface 111 of the active reflector 110 facing the +X direction. On route (2), the active reflector 110 is located within the non-line-of-sight area 30B.

[0040] Route (3) is a route that changes the position of the active reflector 110 in the Y direction from coordinates (X, Y, Z) = (5, -25, 1.5) to (5, 25, 1.5) with the reflective surface 111 of the active reflector 110 facing the -X direction. Route (3) changes the position of the active reflector 110 in a straight line at X = 5 m. At the position X = 5 m, the boundary between the line-of-sight area 30A and the non-line-of-sight area 30B indicated by dashed line A in FIG. 1 is at positions Y = 9.3 m and Y = -9.3 m. Therefore, in the case of route (3), the active reflector 110 is located within the line-of-sight area 30A when the positions in the Y direction are -9 m, -8 m, -7 m, 7 m, 8 m, and 9 m.

[0041] 6(B) and Y=0m in FIGS. 7(A) and 7(B) show the channel capacities when the receivers 21 to 23 receive signals when the active reflector 110 is not present in the region 1. The channel capacities of the receivers 21 and 22 in the non-line-of-sight region 30B are approximately zero when the active reflector 110 is not present in the region 1, and therefore the receivers 21 and 22 are located in the dead zone.

[0042] As shown in Figure 6(B), when the active reflector 110 was not present, the channel capacities of the receivers 21 and 22 were approximately zero. When the position of the active reflector 110 was changed along the route (1), the channel capacities of the receivers 21 and 22 tended to become higher than the channel capacity when the active reflector 110 was not present as the active reflector 110 approached the intersection 2I. The intersection 2I is located in the range of X = -6 m to 6 m. The reason why the channel capacity of the receiver 21 was higher than that of the receiver 22 is thought to be because the reflecting surface 111 of the active reflector 110 faces in the -Y direction, and an increase in reflected waves reaches the receiver 21, which is located in the non-line-of-sight area 30B on the -Y side of the intersection 2I.

[0043] Furthermore, it was confirmed that the receiver 23 located within the line-of-sight area 30A had a tendency to have a higher overall channel capacity than when there was no active reflector 110. This is thought to be because the number of radio waves reaching the receiver 23 increased due to an increase in reflected waves even within the line-of-sight area 30A.

[0044] The reason why the channel capacity of the receiver 23 showed very high values ​​when the active reflector 110 was located at X = -25 m and -20 m is thought to be due to the influence of the active reflector 110 being located close to the radio base station 10, causing reflected waves emitted from the radio base station 10 and reflected by the active reflector 110 to enter the receiver 23. The reason why the channel capacity of the receiver 23 showed very high values ​​when the active reflector 110 was located at X = 20 m and 25 m is thought to be due to the influence of the active reflector 110 being located close to the receiver 23, causing reflected waves emitted from the radio base station 10 and reflected by the active reflector 110 to enter the receiver 23.

[0045] 7(A), when the position of the active reflector 110 is changed along the route (2), the channel capacity of the receivers 21 to 23 tends to be higher when the position of the active reflector 110 in the Y direction is within the ranges of -10 m to -7 m and 7 m to 10 m than when the active reflector 110 is not present. Note that the intersection 2I is located in the range of Y=-6 m to 6 m.

[0046] It was found that when the position of the active reflector 110 in the Y direction is between -10 m and -7 m, the channel capacity of receiver 21 is higher than that of receiver 22, and therefore more reflected waves reach receiver 21, which is located closer to the active reflector 110. It was also found that when the position of the active reflector 110 in the Y direction is between 7 m and 10 m, the channel capacity of receiver 22 is higher than that of receiver 21, and therefore more reflected waves reach receiver 22, which is located closer to the active reflector 110.

[0047] Furthermore, for the receiver 23 located within the line-of-sight area 30A, when the position of the active reflector 110 in the Y direction is within the range of -10 m to -7 m or 7 m to 10 m, it was confirmed that the channel capacity tends to be higher than when the active reflector 110 is not present. This is thought to be because the active reflector 110 is located near the intersection 2I, which increases the number of reflected waves even within the line-of-sight area 30A, and therefore increases the number of radio waves that reach the receiver 23.

[0048] As shown in Figure 7(B), when the position of the active reflector 110 is changed along the path (3), the channel capacity of the receivers 21 to 23 tends to be higher than the channel capacity when the active reflector 110 is not present when the Y-direction position of the active reflector 110 is within the range of -20m to -7m and 7m to 20m.

[0049] It was found that when the position of the active reflector 110 in the Y direction is between -20 m and -7 m, the channel capacity of receiver 21 is higher than that of receiver 22, and therefore more reflected waves reach receiver 21, which is located closer to the active reflector 110. It was also found that when the position of the active reflector 110 in the Y direction is between 7 m and 20 m, the channel capacity of receiver 22 is higher than that of receiver 21, and therefore more reflected waves reach receiver 22, which is located closer to the active reflector 110.

[0050] Furthermore, the channel capacity of receivers 21 and 22 was particularly high when the Y-direction positions of the active reflector 110 within the line-of-sight area 30A on the +Y and -Y sides of road 2Y were -9 m, -8 m, -7 m, 7 m, 8 m, and 9 m. This is thought to be because the active reflector 110 is positioned within the line-of-sight area 30A on the +Y and -Y sides of road 2Y with its reflective surface 111 facing the wireless base station 10, and therefore some radio waves from the wireless base station 10 directly reach the reflective surface 111, increasing the number of reflected waves that reach receivers 21 and 22 in the non-line-of-sight area 30B.

[0051] Furthermore, for the receiver 23 located within the line-of-sight area 30A, it was confirmed that when the position of the active reflector 110 in the Y direction was −9 m, −8 m, −7 m, 7 m, 8 m, and 9 m, the channel capacity tended to be higher than when the active reflector 110 was not present. This is thought to be because, even for the receiver 23 located within the line-of-sight area 30A, the number of reflected waves that reach the receiver 23 is increased by placing the active reflector 110 within the line-of-sight area 30A on the +Y and −Y sides of the road 2Y.

[0052] The first simulation showed that installing the active reflector 110 near the intersection 2I can increase the number of reflected waves that reach the receivers 21 and 22 located within the dead zone. In particular, as shown by the results of path (3), it was found that installing the reflective surface 111 facing the wireless base station 10 within the line-of-sight area 30A can significantly increase the number of reflected waves that reach the receivers 21 and 22 located within the dead zone.

[0053] <Second Simulation> 8 is a diagram showing the results of the second simulation. In the second simulation, the difference in channel capacity (bit / s / Hz) for different sizes (areas) of the active reflector 110 was calculated. The channel capacity is the channel capacity (bit / s / Hz) when the receivers 21 to 23 receive radio waves transmitted from the wireless base station 10. The positions of the wireless base station 10 and the receivers 21 to 23 are the same as in the first simulation.

[0054] In the second simulation, the position of the active reflector 110 was the same as that in the first simulation where Y = 9 m on route (3), that is, (X, Y, Z) = (5, 9, 1.5). That is, the active reflector 110 was placed within the line-of-sight area 30A on the +Y direction side of the road 2Y, with its reflecting surface 111 facing the wireless base station 10. In addition, the reflection angle of the active reflector 110 was varied in 1-degree increments within a range of ±90 degrees with respect to the normal vector of the reflecting surface 111 when viewed on the XY plane.

[0055] The area of ​​the active reflector 110 is 0m 2 The results shown in the figure represent the results when the active reflector 110 is not installed. 2 (300mm x 300mm) and 0.64m 2 When the area of ​​the active reflector 110 was set to 0.09 m (800 mm x 800 mm), the channel capacity of the receivers 21 and 22 increased dramatically compared to when the active reflector 110 was not installed. 2 than 0.64m 2 In this case, the area of ​​the active reflector 110 is set to 0.09 m. 2 (300mm x 300mm) and 0.64m 2 (800mm x 800mm) and the result is shown below, but 1.00m 2 It was confirmed that the area of ​​the active reflector 110 showed an increasing tendency up to (1000 mm × 1000 mm). 2 When the area is reduced to 0.01 m, the channel capacity of receivers 21 and 22 is 2 It was confirmed that if the active reflector 110 is 100 mm or larger, the light intensity increases compared to when the active reflector 110 is not installed.

[0056] The second simulation revealed that the larger the size of the active reflector 110, the more reflected waves can reach the receivers 21 and 22 located in the dead zone. 2 ~1.00m 2 was found to be suitable.

[0057] <Third Simulation> FIG. 9 is a diagram showing the position of the reflecting surface 111 of the active reflector 110 in the third simulation. In the third simulation, the active reflector 110 was placed in 12 locations, and the channel capacity of the receivers 21 to 23 when placed at each location was calculated. FIG. 9 shows the outer wall on the -X direction side of the building 5A. The positions of the wireless base station 10 and the receivers 21 to 23 are the same as in the first simulation. The size of the active reflector 110 is 0.09 m 2 The active reflector 110 has a reflection angle of ±90 degrees relative to the normal vector of the reflection surface 111 in the XY plane view at intervals of 1 degree.

[0058] Four of the 12 positions of the active reflector 110 are the same as those for path (3) in the first simulation, where Y = 7 m, 8 m, 9 m, and 10 m, and are (X, Y, Z) = (5, 7, 1.5), (5, 8, 1.5), (5, 9, 1.5), and (5, 10, 1.5). The remaining eight positions are at different heights, 3 m and 6 m. That is, the 12 positions are (X, Y, Z) = (5, 7, 1.5), (5, 7, 3), (5, 7, 6), (5, 8, 1.5), (5, 8, 3), (5, 8, 6), (5, 9, 1.5), (5, 9, 3), (5, 9, 6), (5, 10, 1.5), (5, 10, 3), and (5, 10, 6).

[0059] The points (X, Y, Z) = (5, 7, 1.5), (5, 7, 3), (5, 7, 6), (5, 8, 1.5), (5, 8, 3), (5, 8, 6), (5, 9, 1.5), (5, 9, 3), and (5, 9, 6) are within the line-of-sight area 30A, and the active reflector 110 is disposed with its reflective surface 111 facing the wireless base station 10 within the line-of-sight area 30A on the +Y direction side of the road 2Y. Therefore, a straight line (shortest optical path) exists between the reflective surface 111 and the wireless base station 10. The points (X, Y, Z) = (5, 10, 1.5), (5, 10, 3), and (5, 10, 6) are within the non-line-of-sight area 30B, and the active reflector 110 is disposed within the non-line-of-sight area 30B on the +Y direction side of the road 2Y. No straight line exists between the reflective surface 111 and the wireless base station 10. 9 are positions at X=5 m. The outer wall on the −X direction side of building 5A is located at X=6 m, and therefore reflective surface 111 is located 1 m further in the −X direction than the outer wall on the −X direction side of building 5A.

[0060] Fig. 10 shows the results of the third simulation. In the third simulation, differences in the channel capacities (bit / s / Hz) of the receivers 21 to 23 for different heights of the active reflector 110 and for different line-of-sight areas 30A and non-line-of-sight areas 30B were calculated. Note that Y=0m in Fig. 10 shows the channel capacities when the receivers 21 to 23 receive signals when the active reflector 110 is not present in area 1.

[0061] 10(A) shows the channel capacity of the receivers 21 to 23 when the height of the active reflector 110 is 1.5 m (Z = 1.5 m). The channel capacity of the receivers 21 and 22 was significantly increased when the active reflector 110 was within the line-of-sight area 30A at Y = 7 m, 8 m, and 9 m, compared to when the active reflector 110 was not present. This is thought to be because when the active reflector 110 was within the line-of-sight area 30A, there was a straight line (shortest optical path) connecting the reflecting surface 111 and the wireless base station 10 over the entire surface of the reflecting surface 111. This resulted in radio waves arriving directly from the wireless base station 10, and these directly arriving radio waves were reflected by the reflecting surface 111, resulting in an increase in the number of reflected waves arriving at the receivers 21 and 22 in the dead zone. In particular, the increase in channel capacity was large when Y = 8 m, which was close to the boundary between the line-of-sight area 30A and the non-line-of-sight area 30B. When Y=7 m, the increase in channel capacity of the receiver 22, which is located on the same road 2Y as the active reflector 110 in the +Y direction, was greater than that of the receiver 21.

[0062] Furthermore, when the active reflector 110 is located in the non-line-of-sight area 30B at Y=10 m, the channel capacity of the receivers 21 and 22 is lower than when it is located in the line-of-sight area 30A, but is higher than when there is no active reflector 110. The position at Y=10 m is within the non-line-of-sight area 30B, but is close to the line-of-sight area 30A. This is thought to be because the reflected waves reflected by the buildings 5A to 5D are reflected by the reflecting surfaces 111, and the number of reflected waves reaching the receivers 21 and 22 located in the dead zone increases.

[0063] Furthermore, when the active reflector 110 was located within the line-of-sight area 30A at distances Y=7 m, 8 m, and 9 m, the channel capacity of the receiver 23 increased compared to when the active reflector 110 was not present. This is thought to be because the presence of the active reflector 110 within the line-of-sight area 30A caused radio waves that would otherwise reach the reflecting surface 111 from the wireless base station 10 to be reflected by buildings 5B and the like, increasing the number of reflected waves that reached the receiver 23 within the line-of-sight area 30A. In particular, the increase in channel capacity was large when Y=9 m, which is close to the boundary between the line-of-sight area 30A and the non-line-of-sight area 30B. Furthermore, when Y=10 m, the channel capacity of the receiver 23 was approximately the same as when the active reflector 110 was not present.

[0064] 10(B) shows the channel capacity of the receivers 21 to 23 when the height of the active reflector 110 is 3.0 m (Z = 3 m). The channel capacity of the receivers 21 and 22 was significantly increased when the active reflector 110 was within the line-of-sight area 30A at Y = 7 m, 8 m, and 9 m, compared to when the active reflector 110 was not present. In particular, the increase in channel capacity was large when Y = 7 m and 8 m, which are close to the boundary between the line-of-sight area 30A and the non-line-of-sight area 30B. When Y = 7 m and 8 m, the increase in channel capacity of the receiver 22, which is located within the road 2Y on the same +Y direction side as the active reflector 110, was larger than that of the receiver 21. As in the case of Z=1.5 m, there is a straight line (shortest optical path) connecting the reflecting surface 111 and the wireless base station 10 over the entire reflecting surface 111, so it is thought that there are radio waves that arrive directly from the wireless base station 10, and these directly arriving radio waves are reflected by the reflecting surface 111, increasing the number of reflected waves that reach the receivers 21 and 22 within the dead zone.

[0065] Furthermore, when the active reflector 110 is located within the non-line-of-sight area 30B at Y=10 m, the channel capacity of the receivers 21 and 22 is lower than when it is located within the line-of-sight area 30A, but is increased compared to when there is no active reflector 110. As with the case of Z=1.5 m, the position at Y=10 m is within the non-line-of-sight area 30B, but is close to the line-of-sight area 30A. This is thought to be because the reflected waves reflected by the buildings 5A to 5D are reflected by the reflecting surfaces 111, and the number of reflected waves reaching the receivers 21 and 22 located within the dead zone increases.

[0066] Furthermore, the channel capacity of the receiver 23 increased compared to when the active reflector 110 was not present when the active reflector 110 was located at Y = 7 m, 8 m, and 9 m within the line-of-sight region 30A and when Y = 10 m within the non-line-of-sight region 30B. As with the case of Z = 1.5 m, the presence of the active reflector 110 within the line-of-sight region 30A is thought to be due to the fact that radio waves that would otherwise directly reach the reflecting surface 111 from the wireless base station 10 are reflected by buildings 5B and the like, increasing the number of reflected waves that reach the receiver 23 within the line-of-sight region 30A. In particular, the increase in channel capacity was large when Y = 9 m, which is close to the boundary between the line-of-sight region 30A and the non-line-of-sight region 30B.

[0067] Furthermore, when Y=10 m, the channel capacity of receiver 23 was approximately the same as when Y=7 m and 8 m. Although the position of Y=10 m is within non-line-of-sight area 30B, it is close to line-of-sight area 30A, and this is thought to be because the reflected waves reflected by buildings 5A to 5D are reflected by reflecting surface 111, increasing the number of reflected waves that reach receiver 23 within line-of-sight area 30A. As described above, when Z=3 m, a better tendency was observed overall than when Z=1.5 m.

[0068] 10(C) shows the channel capacities of the receivers 21 to 23 when the height of the active reflector 110 is 6.0 m (Z = 6 m). The channel capacities of the receivers 21 and 22 increased when the active reflector 110 was located within the line-of-sight area 30A at Y = 7 m, 8 m, and 9 m, compared to when the active reflector 110 was not present. However, the increase was smaller than when Z = 1.5 m and 3 m. When Y = 7 m, the increase in channel capacity of the receiver 22, which is located within the road 2Y on the same +Y direction side as the active reflector 110, was greater than that of the receiver 21. As in the cases of Z = 1.5 m and 3 m, a straight line (shortest optical path) connecting the reflecting surface 111 and the wireless base station 10 exists over the entire reflecting surface 111. This is thought to be because, as in the cases of Z = 1.5 m and 3 m, some radio waves arrive directly from the wireless base station 10, and the directly arriving radio waves are reflected by the reflecting surface 111, resulting in an increase in the reflected waves arriving at the receivers 21 and 22, which are located within the dead zone.

[0069] Furthermore, when the active reflector 110 is located within the non-line-of-sight region 30B (Y=10 m), the channel capacity of the receivers 21 and 22 is higher than when the active reflector 110 is not present, but the increase is small. Although not shown here, the channel capacity is smaller when Z=6 m than when Z=5 m.

[0070] Furthermore, the channel capacity of the receiver 23 was approximately the same as when the active reflector 110 was not present, in all cases where Y = 7 m, 8 m, 9 m, and 10 m. Although not shown here, the channel capacity of the receiver 23 was smaller when Z = 6 m than when Z = 5 m. From the above, it was found that the height of the active reflector 110 should preferably be 1.5 m or more and 5 m or less.

[0071] <Fourth Simulation> Figure 11 shows the results of the fourth simulation. Figures 11(A), 11(B), and 11(C) show the optical paths (ray paths) of direct waves that travel directly from the wireless base station 10 to the receivers 21, 22, and 23, respectively, and reflected waves that are reflected along the way and arrive at the receivers. The coordinates of the active reflector 110 in Figures 11(A), 11(B), and 11(C) are (X, Y, Z) = (5, 7, 1.5), (5, 10, 1.5), and (5, 15, 1.5), respectively. The reflecting surface 111 faces the -X direction.

[0072] The size of the reflecting surface 111 of the active reflector 110 is 300 mm in length and 300 mm in width, and the area is 0.09 m 2 The position of the active reflector 110 is the position of the center of gravity of the reflecting surface 111. The reflection angle of the active reflector 110 is varied in 1-degree increments within a range of ±90 degrees with respect to the normal vector of the reflecting surface 111 when viewed on the XY plane. Note that in Figs. 11(A), 11(B), and 11(C), in order to make the ray paths easier to see, only the layout of the buildings 5A to 5D is shown, and the receivers 21, 22, and 23 and other components and their reference numerals are omitted.

[0073] That is, in Fig. 11(A), the active reflector 110 is located within the line-of-sight area 30A. In Fig. 11(B), the active reflector 110 is located within the non-line-of-sight area 30B, but near the boundary with the line-of-sight area 30A. In Fig. 11(C), the active reflector 110 is located within the non-line-of-sight area 30B, more than 5 m away from the line-of-sight area 30A. This simulation was performed using a simulator that calculates ray paths.

[0074] 11(A), it was found that when Y=7 m, the reflected wave reflected by the active reflector 110 was more likely to reach the receiver 21. In addition to the direct wave from the wireless base station 10, reflected waves reflected by the exterior walls of buildings 5B and 5C were also incident on the active reflector 110. It was also confirmed that the reflected wave reflected by the active reflector 110 sometimes reaches the receiver 21 directly and sometimes reaches it after being reflected by the exterior wall of building 5C on the +X direction side.

[0075] 11(A), it was found that the reflected wave reflected by the active reflector 110 was more likely to reach the receiver 22 when Y=7 m. In addition to the direct wave from the wireless base station 10, reflected waves reflected by the outer walls of buildings 5B and 5C were also incident on the active reflector 110. It was also confirmed that the reflected wave reflected by the active reflector 110 sometimes reaches the receiver 22 directly and sometimes reaches the receiver 22 after being reflected by the outer walls of buildings 5A and 5B.

[0076] 11(A), when Y=7 m, it was found that in addition to the direct wave from the wireless base station 10 and the waves reflected by the exterior walls of the buildings 5A to 5D, the reflected wave reflected by the active reflector 110 also reaches the receiver 23, although the ray path is small. In addition to the direct wave from the wireless base station 10, the reflected waves reflected by the exterior walls of the buildings 5B and 5C also reach the active reflector 110. It was also confirmed that the reflected wave reflected by the active reflector 110 does not reach the receiver 23 directly, but rather reaches it after being reflected by the exterior walls of the buildings 5A and 5D.

[0077] As shown in FIG. 11(A), when the position of the active reflector 110 is Y=7 m, the effect of obtaining ray paths to the receivers 21 and 22 located within the dead zone was significant.

[0078] 11(B), when Y=10 m, the active reflector 110 is within the non-line-of-sight area 30B, but is close to the boundary between the line-of-sight area 30A and the non-line-of-sight area 30B. Therefore, it was found that the reflected waves reflected by the active reflector 110 after being reflected by the exterior walls of buildings 5B and 5C are more likely to reach the receiver 21. It was also confirmed that the reflected waves reflected by the active reflector 110 may reach the receiver 21 directly, may be reflected by the exterior wall on the +X side of building 5C, or may be reflected by the surface of road 2Y and then reflected by the exterior wall on the +X side of building 5C. It was found that the number of reflections increased compared to when Y=7 m.

[0079] 11(B), it was found that, as in the case of receiver 21, reflected waves reflected by the active reflector 110 after being reflected by the exterior walls of buildings 5B and 5C are more likely to reach receiver 22 when Y=10 m. It was also confirmed that the reflected waves reflected by active reflector 110 may reach receiver 21 directly, may reach receiver 21 after being reflected by the exterior wall on the +X direction side of building 5B, or may reach receiver 21 after being reflected by the surface of road 2Y and then by the exterior wall on the +X direction side of building 5B. Although active reflector 110 is within the non-line-of-sight area 30B, it is closer to receiver 22 than when Y=7 m, and therefore the number of ray paths reaching receiver 22 directly from active reflector 110 is increased compared to when Y=7 m.

[0080] Furthermore, as shown in Figure 11(B), when Y = 10 m, it was found that in addition to the direct wave from the radio base station 10 and the reflected waves reflected by the outer walls of buildings 5A to 5D, a ray path was generated that reached the receiver 23, where a reflected wave reflected by the active reflector 110 and further reflected by building 5B reached the receiver 23.

[0081] As shown in FIG. 11(B), when the position of the active reflector 110 is Y=10 m, ray paths to the receivers 21 and 22 in the dead zone are obtained, and the number of ray paths to the receiver 23 increases.

[0082] 11(C), it was found that when Y=15 m, the reflected wave reflected by the active reflector 110 reaches the receiver 21. The reflected wave from the wireless base station 10 does not reach the active reflector 110 directly, but is instead reflected by the outer walls of the buildings 5A, 5B, and 5C. It was also confirmed that the reflected wave reflected by the active reflector 110 sometimes reaches the receiver 21 directly and sometimes reaches the receiver 21 after being reflected by the outer walls of the buildings 5A and 5C.

[0083] 11(C), it was found that when Y=15 m, the reflected wave reflected by the active reflector 110 did not reach the receiver 22. Because the active reflector 110 is located within the non-line-of-sight area 30B, the number of reflections of the ray path reaching the receiver 22 increased compared to when Y=7 m and 10 m.

[0084] Also, as shown in Figure 11(C), when Y = 15 m, the receiver 23 receives the direct wave from the radio base station 10 and the reflected wave reflected by the outer walls of the buildings 5A to 5D, and no ray path through which the reflected wave reflected by the active reflector 110 reaches the receiver 23 is observed.

[0085] As shown in FIG. 11(C), when the position of the active reflector 110 is Y=15 m, ray paths to the receivers 21 and 22 in the dead zone are obtained, but the ray path to the receiver 23 does not increase.

[0086] From the results of Figures 11(A), 11(B), and 11(C), it was found that in order to increase the ray paths to receivers 21 and 22 in the dead zone area while increasing the ray paths to receiver 23 in the line-of-sight area 30A, the positions in the Y direction of the active reflector 110 with its reflective surface 111 facing the wireless base station 10 are preferably Y=7m and Y=10m.

[0087] <5th Simulation> 12 and 13 are diagrams showing simulation models. Five simulation models 1A, 1B, 1C, 1D, and 1E are shown in FIGS. 12 and 13. In FIGS. 12 and 13, only the layout of buildings 5A to 5D and active reflectors 110, 110A, and 110B are shown, and receivers 21, 22, and 23 and other components and their reference numerals are omitted. The size of the active reflectors 110, 110A, and 110B is 0.09 mm. 2 (300 mm × 300 mm). The reflection angles of the active reflectors 110, 110A, and 110B were varied in 5-degree intervals within a range of ±90 degrees relative to the normal vector of the reflection surface 111 when viewed from the XY plane. The two active reflectors 110A and 110B of the simulation models 1C to 1E have the same configuration as the single active reflector 110 of the simulation model 1B.

[0088] Simulation model 1A shown in Fig. 12(A) is a simulation model for comparison and does not include an active reflector 110. Simulation model 1B shown in Fig. 12(B) includes one active reflector 110 located at a position (X, Y, Z) = (5, 7, 1.5). The reflecting surface 111 faces the -X direction toward the wireless base station 10.

[0089] 12(C) includes two active reflectors 110A and 110B, which are arranged at positions (X, Y, Z) = (5, 7, 1.5) and (5, -7, 1.5), respectively. The reflecting surfaces 111 of the two active reflectors 110A and 110B both face the -X direction toward the wireless base station 10. The two active reflectors 110A and 110B are arranged adjacent to each other across an intersection 2I. Because the intersection 2I is a line-of-sight area 30A, the two active reflectors 110A and 110B are arranged adjacent to each other across the line-of-sight area 30A. The position of the active reflector 110A is the same as the position of the active reflector 110 in the simulation model 1B, so the simulation model 1C has a configuration in which the active reflector 110B is added to the simulation model 1B.

[0090] Since the two active reflectors 110A and 110B constitute the reflector system 100, the simulation model 1C shown in Fig. 12(C) is a simulation model including the reflector system 100. The active reflector 110A is an example of a first active reflector, and the reflecting surface 111 of the active reflector 110A is an example of a first reflecting surface. The active reflector 110B is an example of a second active reflector, and the reflecting surface 111 of the active reflector 110B is an example of a second reflecting surface.

[0091] 13(A) is a simulation model including a reflector system 100. Two active reflectors 110A and 110B are disposed at positions (X, Y, Z) = (5, 7, 1.5) and (-5, 7, 1.5), respectively. The reflecting surface 111 of the active reflector 110A faces in the -X direction toward the wireless base station 10. The reflecting surface 111 of the active reflector 110B faces in the +X direction and faces the reflecting surface 111 of the active reflector 110A across the non-line-of-sight area 30B of the road 2Y on the +Y direction side.

[0092] The position of the active reflector 110A is the same as the position of the active reflector 110 in the simulation model 1B, so the simulation model 1D has a configuration in which the active reflector 110B is added to the simulation model 1B. The active reflector 110A is an example of a first active reflector, and the reflecting surface 111 of the active reflector 110A is an example of a first reflecting surface. The active reflector 110B is an example of a second active reflector, and the reflecting surface 111 of the active reflector 110B is an example of a second reflecting surface.

[0093] Simulation model 1E shown in Figure 13(B) is a simulation model that includes the reflector system 100. Two active reflectors 110A and 110B are arranged at positions (X, Y, Z) = (5, 7, 1.5) and (-5, -7, 1.5), respectively. The reflecting surface 111 of active reflector 110A faces the -X direction toward the wireless base station 10. The reflecting surface 111 of active reflector 110B faces the +X direction. The reflecting surfaces 111 of the two active reflectors 110A and 110B are positioned diagonally opposite each other with an intersection 2I in between. Because the intersection 2I is within the line-of-sight area 30A, the reflecting surfaces 111 of the two active reflectors 110A and 110B are arranged diagonally opposite each other with the line-of-sight area 30A in between.

[0094] Since the position of active reflector 110A is the same as the position of active reflector 110 in simulation model 1B, simulation model 1E has a configuration in which active reflector 110B is added to simulation model 1B. Active reflector 110A is an example of a first active reflector, and the reflecting surface 111 of active reflector 110A is an example of a first reflecting surface. Active reflector 110B is an example of a second active reflector, and the reflecting surface 111 of active reflector 110B is an example of a second reflecting surface.

[0095] 14 is a diagram showing the results of the fifth simulation. In the fifth simulation, the channel capacities of the receivers 21 to 23 in the simulation models 1A to 1E were calculated. Here, the channel capacities of the receivers 21 to 23 are shown as bar graphs. For each of the receivers 21 to 23, the channel capacities in the simulation models 1A to 1E are shown from left to right.

[0096] 14, the channel capacity of the receiver 21 of the simulation models 1B to 1E in which the active reflector 110 or 110A and 110B is arranged is significantly increased compared to the simulation model 1A in which the active reflectors 110, 110A, and 110B are not arranged. It was found that by arranging the active reflectors 110, 110A, and 110B at the above-mentioned positions, the channel capacity of the receiver 21 arranged in the dead band area can be significantly increased.

[0097] Simulation model 1C showed the greatest increase in the channel capacity of the receiver 21, and the best results were obtained by arranging two active reflectors 110A and 110B side by side across the intersection 2I facing the wireless base station 10. Simulation models 1D and 1E, which include two active reflectors 110A and 110B, also showed a slight increase in the channel capacity of the receiver 21 compared to simulation model 1B, which includes a single active reflector 110. Simulation models 1D and 1E were obtained by adding a facing and diagonally facing active reflector 110B to simulation model 1B. Therefore, it was confirmed that adding an active reflector 110B that does not face the wireless base station 10 increases the number of reflected waves that reach the receiver 21.

[0098] It was also confirmed that the channel capacity of the receiver 22 in the simulation models 1B to 1E was significantly increased compared to the simulation model 1A in which the active reflectors 110, 110A, and 110B were not installed. The channel capacity of the receiver 22 increased the most in the simulation model 1C, and the best results were obtained by arranging the two active reflectors 110A and 110B side by side across the intersection 2I facing the wireless base station 10.

[0099] Furthermore, simulation models 1D and 1E, which include two active reflectors 110A and 110B, have a slightly increased channel capacity of receiver 21 compared to simulation model 1B, which includes one active reflector 110. Therefore, it was confirmed that, similar to receiver 21, adding active reflector 110B that does not face the wireless base station 10 increases the number of reflected waves that reach receiver 22.

[0100] It was also confirmed that the channel capacity of the receiver 23 in the simulation models 1B to 1E was slightly increased compared to the simulation model 1A in which the active reflectors 110, 110A, and 110B were not arranged.

[0101] From the above, it was found in the fifth simulation that adding a second active reflector 110B can increase the channel capacity of the receivers 21 and 22 in the dead band area more than the simulation model 1B which includes only one active reflector 110. In other words, it was found that using the reflector system 100 can increase the channel capacity of the receivers 21 and 22 in the dead band area more than using the active reflector 110 alone.

[0102] Furthermore, the second active reflector 110 does not have to face the wireless base station 10, but it has been found that facing the wireless base station 10 as in simulation model 1C can more effectively increase the channel capacity of the receivers 21 and 22 in the dead zone. For this reason, when using the reflector system 100, it is estimated that it is better to have as many active reflectors 110 facing the wireless base station 10 as possible.

[0103] <Summary of Simulations 1 to 5> As described above, the first to fifth simulations were performed. For the routes (1) to (3) in the first simulation, it was found that, except for the case of X=±25 m and ±20 m in the route (1), when the active reflector 110 was placed near the intersection 2I, the channel capacity of the receivers 21 to 23 was significantly increased compared to when the active reflector 110 was not present.

[0104] When the active reflector 110 is located near the intersection 2I on routes (1) to (3), the position of the active reflector 110 is close to the boundary between the line-of-sight area 30A and the non-line-of-sight area 30B. The channel capacity of the receivers 21 to 23 increases not only when the active reflector 110 is located within the line-of-sight area 30A, but also when the active reflector 110 is located within the non-line-of-sight area 30B, such as when Y=±7 m, ±9 m, and ±10 m on route (2) and when Y=±10 m on route (3).

[0105] For this reason, it is considered sufficient that the reflective surface 111 of the active reflector 110 is located within the boundary area located at the boundary between the line-of-sight area 30A and the non-line-of-sight area 30B. The boundary area is a three-dimensional area located at the boundary including the boundary between the line-of-sight area 30A and the non-line-of-sight area 30B, and has a width in the Y direction. For example, when X = 5 m, the width of the boundary area in the Y direction is approximately Y = 7 m to 10 m and Y = -7 m to -10 m. Furthermore, even if the entire reflective surface 111 of the active reflector 110 is not located within the boundary area, it is sufficient that at least a part of the reflective surface 111 is located within the boundary area.

[0106] As described above, the active reflector 110 may be provided so that at least a portion of the reflecting surface 111 is located within the boundary area between the line-of-sight area 30A and the non-line-of-sight area 30B. By arranging the active reflector 110 in this manner, the channel capacity of the receivers 21 and 22 located within the dead zone can be increased.

[0107] Therefore, it is possible to provide an active reflector 110 that can efficiently eliminate the dead zone, and a method for arranging the active reflector 110. The method for arranging the active reflector 110 calculates the line-of-sight area 30A and the non-line-of-sight area 30B, and arranges the active reflector 110 so that at least a part of the reflective surface 111 is located in the boundary area between the line-of-sight area 30A and the non-line-of-sight area 30B.

[0108] Furthermore, when the active reflector 110 is provided with its reflecting surface 111 facing the wireless base station 10 as in the path (3), the channel capacity of the receivers 21 and 22 in the dead zone is increased compared to when the active reflector 110 is disposed with its reflecting surface 111 not facing the wireless base station 10 as in the path (2). For this reason, by providing the active reflector 110 with its reflecting surface 111 facing the wireless base station 10, it is possible to more efficiently eliminate the dead zone.

[0109] In the second simulation, the size of the reflecting surface 111 of the active reflector 110 is 0.09 m 2 ~1.00m 2 Therefore, the size of the reflecting surface 111 is set to 0.09 mm. 2 ~1.00m 2 By setting the value of the dead band to 0, the dead band can be eliminated more efficiently.

[0110] In addition, in the third simulation, the reflecting surface 111 of the active reflector 110 was positioned at 12 locations on the path (3) with different heights and Y-direction positions. As a result, the channel capacity of the receivers 21 and 22 in the dead zone increased when the height was between 1.5 m and 5 m. As for the Y-direction position, for example, when X = 5, positioning the reflecting surface 111 within the range of Y = 7 m to 10 m increased the channel capacity of the receivers 21 and 22 in the dead zone. This tendency in the Y-direction position was the same as in the first simulation. Therefore, by setting the height of the reflecting surface 111 of the active reflector 110 to between 1.5 m and 5 m, the dead zone can be more efficiently eliminated.

[0111] In the fourth simulation, in order to increase the ray paths to the receiver 23 in the line-of-sight area 30A, the channel capacity of the receivers 21 and 22 in the dead zone increased when the Y-direction positions of the active reflector 110, with the reflecting surface 111 facing the wireless base station 10, were Y = 7 and Y = 10. This tendency of the Y-direction position was the same as in the first simulation.

[0112] Furthermore, in the fifth simulation, by introducing a reflector system 100 with a second active reflector 110B added, the channel capacity of the receivers 21 and 22 in the dead zone was increased compared to the simulation model 1B that included only one active reflector 110. Therefore, it is possible to provide a reflector system 100 that can efficiently eliminate the dead zone.

[0113] Furthermore, in the reflector system 100, the channel capacity of the receivers 21 and 22 in the dead zone is increased more when both of the two active reflectors 110A and 110B face the wireless base station 10. Therefore, by arranging the two active reflectors 110A and 110B so that their reflective surfaces 111 face the wireless base station 10 and are adjacent to each other across the line-of-sight area 30A, it is possible to provide a reflector system 100 that can more efficiently eliminate the dead zone. Note that the active reflector 110B, which is an example of a second active reflector, may be arranged adjacent to the active reflector 110 in the non-line-of-sight area 30B.

[0114] Furthermore, when the second active reflector 110B does not face the wireless base station 10, the channel capacity of the receivers 21 and 22 in the dead zone can be increased compared to when only one active reflector 110 is included by locating the second active reflector 110B opposite the active reflector 110A across the non-line-of-sight region 30B or diagonally opposite the line-of-sight region 30A. Therefore, by locating the second active reflector 110B opposite the active reflector 110A across the non-line-of-sight region 30B or diagonally opposite the line-of-sight region 30A, it is possible to provide a reflector system 100 that can more efficiently eliminate dead zones.

[0115] Although the above describes a configuration in which the line-of-sight area 30A and the non-line-of-sight area 30B are separated in the XY plane, the line-of-sight area 30A and the non-line-of-sight area 30B may be separated in the vertical direction, or in a direction oblique to the X-axis, Y-axis, or Z-axis. In either case, the active reflector 110 may be installed in the boundary area between the line-of-sight area 30A and the non-line-of-sight area 30B.

[0116] The reflector system, active reflector, and active reflector arrangement method according to exemplary embodiments of the present invention have been described above. However, the present invention is not limited to the specifically disclosed embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0117] This international application claims priority based on Japanese Patent Application No. 2021-081556, filed on May 13, 2021, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0118] 1 area 1A~1E Simulation Model 10. Radio base station 11, 12 Antenna unit 30A Line of Sight 30B Non-line-of-sight area 100 Reflector System 110, 110A, 110B Active Reflectors 111 Reflective surface 112 Reflective element

Claims

1. a first active reflector having a first reflecting surface at least a portion of which is provided within a boundary area located at the boundary between a line-of-sight area and a non-line-of-sight area formed by one or more obstructions that block radio waves transmitted from a transmitter, and which reflects the radio waves transmitted from the transmitter with the first reflecting surface whose reflection angle is changeable; a second active reflector having a second reflecting surface provided within the non-line-of-sight area or a second reflecting surface at least a portion of which is provided within the boundary area, and reflecting the radio waves transmitted from the transmitter or the radio waves reflected by the first active reflector with the second reflecting surface capable of changing a reflection angle; , a reflector system.

2. The reflector system according to claim 1 , wherein the first active reflector is provided with the first reflecting surface facing the transmitter.

3. The reflector system according to claim 1 , wherein the second active reflector is provided with the second reflecting surface facing the transmitter or the first reflecting surface.

4. 4. The reflector system according to claim 1, wherein the first active reflector and the second active reflector are arranged so that the first reflective surface and the second reflective surface face each other across the line-of-sight area or the non-line-of-sight area.

5. the second active reflector has at least a portion of the second reflecting surface provided within the boundary area; 4. The reflector system according to claim 1, wherein the first active reflector and the second active reflector are arranged so that the first reflective surface and the second reflective surface are adjacent to each other across the line-of-sight area or the non-line-of-sight area.

6. 2. The reflector system according to claim 1, wherein the height position of the first reflecting surface or the second reflecting surface is at a height position of 1.5 m or more and 5 m or less above ground level.

7. 2. The reflector system according to claim 1, wherein the first active reflector changes the reflection angle of the first reflection surface in response to a drive signal, or the second active reflector changes the reflection angle of the second reflection surface in response to a drive signal.

8. the transmitter is a transmitter that transmits the radio waves in a MIMO (Multiple-Input and Multiple-Output) system, The reflector system according to claim 1 , wherein the first active reflector and the second active reflector reflect the MIMO radio waves at the first reflecting surface and the second reflecting surface.

9. The size of the first reflecting surface and the second reflecting surface is 0.01 m ２ That's all, 1m ２ 2. The reflector system of claim 1, wherein:

10. An active reflector having a reflective surface, at least a portion of which is provided within a boundary area located at the boundary between a line-of-sight area and a non-line-of-sight area formed by one or more obstructions that block radio waves transmitted by a transmitter, and which reflects the radio waves transmitted from the transmitter with the reflective surface, the reflection angle of which can be changed.

11. The active reflector according to claim 10 , wherein the reflective surface is provided toward the transmitter.

12. 11. The active reflector according to claim 10, wherein the reflecting surface is positioned at a height of 1.5 m or more and 5 m or less above ground level.

13. the transmitter is a transmitter that transmits the radio waves using a MIMO system, The active reflector according to claim 10 , wherein the reflecting surface reflects the MIMO radio wave.

14. The size of the reflecting surface is 0.01 m ２ That's all, 1m ２ 11. The active reflector of claim 10, wherein:

15. A method for arranging an active reflector, which has a reflective surface whose reflection angle can be changed so as to reflect radio waves transmitted from a transmitter, comprising: A method for arranging an active reflector, in which the active reflector is arranged so that at least a portion of the reflective surface is located within a boundary area located at the boundary between a line-of-sight area and a non-line-of-sight area formed by one or more obstructions that block radio waves transmitted from a transmitter.

Images