JP7783423B2 - Wireless communication system and wireless communication method - Google Patents

Description

The present disclosure relates to a wireless communication system and a wireless communication method.

Generally, wireless communication systems such as 4G (fourth generation mobile communication system) and 5G (fifth generation mobile communication system) use half-duplex wireless communication in which the transmitting antenna and the receiving antenna are shared. In recent years, full-duplex wireless communication in which the transmitting antenna and the receiving antenna are separate has been proposed in order to improve frequency utilization efficiency (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2021-158557

The wireless communication system disclosed herein includes a first wireless station having a first transmitting/receiving antenna, a second wireless station having a second transmitting/receiving antenna, a first radio wave control plate installed between the first wireless station and the second wireless station and emitting radio waves transmitted from the first transmitting/receiving antenna at a predetermined control angle, and a second radio wave control plate installed between the first wireless station and the second wireless station along a first direction with the first radio wave control plate and emitting radio waves transmitted from the second transmitting/receiving antenna at a predetermined control angle, and at least the first transmitting/receiving antenna is configured as a separate transmitting antenna and receiving antenna.

The wireless communication method disclosed herein includes the steps of receiving radio waves transmitted from a transmitting antenna of a first radio station with a first radio wave control plate, emitting them at a predetermined control angle, and having them received by a transmitting/receiving antenna of a second radio station, and receiving radio waves transmitted from the transmitting/receiving antenna of the second radio station with a second radio wave control plate, emitting them at a predetermined control angle, and having them received by a receiving antenna of the first radio station.

FIG. 1 is a diagram for explaining a full-duplex wireless communication method according to a comparative example. FIG. 2 is a diagram illustrating an example of the configuration of the wireless communication system according to the first embodiment. FIG. 3 is a diagram schematically illustrating an example of a radio wave refraction plate. FIG. 4 is a diagram for explaining the refraction angle of the radio wave refraction plate according to the first embodiment. FIG. 5 is a diagram for explaining a method of installing the radio wave refraction plate according to the first embodiment. FIG. 6 is a diagram illustrating an example of the configuration of a wireless communication system according to a first modification of the first embodiment. FIG. 7 is a diagram illustrating an example of the configuration of a wireless communication system according to a second modification of the first embodiment. FIG. 8 is a diagram illustrating an example of the configuration of a wireless communication system according to the second embodiment.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to this embodiment, and in the following embodiments, identical parts will be designated by the same reference numerals, and duplicate explanations will be omitted.

[Embodiments and Comparative Examples]
(Comparative Example)
Before describing the embodiment, a comparative example will be described first. Fig. 1 is a diagram for explaining a full-duplex wireless communication method according to the comparative example.

As shown in Figure 1, the wireless communication system 1a in the comparative example includes a first wireless station 10 and a second wireless station 20. The wireless communication system 1a is a wireless communication system that performs full-duplex wireless communication.

The first wireless station 10 has a first transmitting antenna 12 and a first receiving antenna 14. The second wireless station 20 has a second transmitting antenna 22 and a second receiving antenna 24.

Let's consider simultaneous wireless communication using radio waves W1 between the first transmitting antenna 12 and the second receiving antenna 24, and wireless communication using radio waves W2, which has the same frequency as radio waves W1, between the second transmitting antenna 22 and the first receiving antenna 14. In this case, to avoid interference between radio waves W1 and W2, it was necessary to ensure a very long distance (e.g., 10 m) for the distance D1 between the first transmitting antenna 12 and the first receiving antenna 14, and for the distance D2 between the second transmitting antenna 22 and the second receiving antenna 24. In other words, in the comparative example, there was a limit to the space available for installing the first wireless station 10 and the second wireless station 20.

[First embodiment]
An example of the configuration of a wireless communication system according to the first embodiment will be described with reference to Fig. 2. Fig. 2 is a diagram for explaining an example of the configuration of a wireless communication system according to the first embodiment.

As shown in FIG. 2, the wireless communication system 1 includes a first wireless station 10, a second wireless station 20, a first radio wave refraction plate 32, and a second radio wave refraction plate 34. The wireless communication system 1 is a wireless communication system that performs full-duplex wireless communication. Compared to the wireless communication system 1a shown in FIG. 1, the wireless communication system 1 includes a first radio wave refraction plate 32 and a second radio wave refraction plate 34.

The first wireless station 10 is equipped with a first transmitting antenna 12 and a first receiving antenna 14. The first transmitting antenna 12 and the first receiving antenna 14 are configured separately. The first transmitting antenna 12 and the first receiving antenna are a type of first transmitting and receiving antenna. The first transmitting antenna 12 and the first receiving antenna 14 are installed on the first wireless station 10 with a predetermined distance (e.g., within 1 m) between them. The first transmitting antenna 12 and the first receiving antenna 14 are configured so that the isolation between them is, for example, 20 dB (decibels) or more. The first transmitting antenna 12 is configured to transmit radio waves W1 toward the first radio wave refraction plate 32.

The second wireless station 20 is equipped with a second transmitting antenna 22 and a second receiving antenna 24. The second transmitting antenna 22 and the second receiving antenna 24 are configured separately. The second transmitting antenna 22 and the second receiving antenna 24 are a type of second transmitting/receiving antenna. The second transmitting antenna 22 and the second receiving antenna 24 are installed on the second wireless station 20 with a predetermined distance (e.g., within 1 m) between them. The second transmitting antenna 22 and the second receiving antenna 24 are configured so that the isolation between the second transmitting antenna 22 and the second receiving antenna 24 is, for example, 20 dB or more. The second transmitting antenna 22 is configured to transmit radio waves W2 toward the second radio wave refraction plate 34.

The first radio wave refraction plate 32 and the second radio wave refraction plate 34 are installed between the first radio station 10 and the second radio station 20. The first radio wave refraction plate 32 and the second radio wave refraction plate 34 are configured to refract received radio waves at a predetermined angle and emit them. The first radio wave refraction plate 32 and the second radio wave refraction plate 34 may be composed of, for example, a metamaterial that changes the phase of the incident wave. The first radio wave refraction plate 32 and the second radio wave refraction plate 34 are a type of radio wave control plate.

Figure 3 is a schematic diagram showing an example of a radio wave refraction plate. As shown in Figure 3, the first radio wave refraction plate 32 may include, for example, a substrate 40, an element 42, an element 44, an element 46, and an element 48. The configuration of the second radio wave refraction plate 34 is the same as the configuration of the first radio wave refraction plate 32, so a description thereof will be omitted.

Element 42, element 44, element 46, and element 48 may be formed on substrate 40. Substrate 40 may have, for example, a rectangular shape, but is not limited to this. Elements 42, element 44, element 46, and element 48 may be arranged two-dimensionally on substrate 40. Specifically, in FIG. 3 , multiple elements 42 may be arranged in a row on the bottom row of substrate 40. Multiple elements 44 may be arranged in a row on the row above element 42. Multiple elements 46 may be arranged in a row on the row above element 44. Multiple elements 48 may be arranged in a row on the row above element 46. In other words, first radio wave refraction plate 32 may have a structure in which multiple elements of different sizes are periodically arranged. Elements 42 to 48 may each vary in the frequency band and phase shift of the radio waves they change. Although elements 42 to 48 each have a rectangular shape, the shape is not limited to this. By changing the size and shape of elements 42, 44, 46, and 48, the frequency band and the amount of phase change of the radio waves to be refracted can be adjusted.

The refraction angle of the radio wave refraction plate according to this embodiment will now be described. Figure 4 is a diagram illustrating the refraction angle of the radio wave refraction plate according to the first embodiment. As shown in Figure 4, the transmitting antenna 12a and the receiving antenna 24a communicate via the radio wave refraction plate 30. When the radio wave W11 transmitted from the transmitting antenna 12a is incident perpendicular to the refraction surface of the radio wave refraction plate 30, i.e., parallel to the normal direction of the radio wave refraction plate 30, the incident angle θ11 of the radio wave W11 with respect to the radio wave refraction plate 30 is 0°. In this embodiment, the emission angle θ0 of the radio wave W12 when the incident angle θ11 = 0° is defined as the refraction angle θ0 of the radio wave refraction plate 30. Note that when the incident angle θ11 ≠ 0°, the refraction angle θ12 is calculated using the following equation (1):

Returning to Figure 2, the first radio wave refraction plate 32 is installed so that radio waves W1 from the first transmitting antenna 12 are incident perpendicularly to the refraction surface. The first radio wave refraction plate 32 is configured to refract radio waves W1 and emit radio waves W3 toward the second wireless station 20. Specifically, the refraction angle θ1 of the first radio wave refraction plate 32 is configured as the angle between the direction connecting the first transmitting antenna 12 to the center of the first radio wave refraction plate 32 and the direction connecting the center of the first radio wave refraction plate 32 to the second receiving antenna 24.

The second radio wave refraction plate 34 is installed so that radio waves W2 from the second transmitting antenna 22 are perpendicularly incident on the refraction surface. The second radio wave refraction plate 34 is configured to refract radio waves W2 and emit radio waves W4 toward the first wireless station 10. Specifically, the refraction angle θ2 of the second radio wave refraction plate 34 is configured as the angle between the direction connecting the second transmitting antenna 22 to the center of the second radio wave refraction plate 34 and the direction connecting the center of the second radio wave refraction plate 34 to the first receiving antenna 14.

The refraction angle θ1 of the first radio wave refraction plate 32 and the refraction angle θ2 of the second radio wave refraction plate 34 are types of control angles of the radio wave control plate.

The first radio wave refraction plate 32 is preferably installed in a Fresnel zone defined based on the straight-line distance between the first transmitting antenna 12 and the first radio wave refraction plate 32 and the straight-line distance between the first radio wave refraction plate 32 and the second receiving antenna 24. The second radio wave refraction plate 34 is preferably installed in a Fresnel zone defined based on the straight-line distance between the second transmitting antenna 22 and the second radio wave refraction plate 34 and the straight-line distance between the second radio wave refraction plate 34 and the first receiving antenna 14.

Figure 5 is a diagram for explaining the installation method of the radio wave refraction plate according to the first embodiment. Below, an example of installing the first radio wave refraction plate 32 will be described. The method of installing the second radio wave refraction plate 34 is the same as the method of installing the first radio wave refraction plate 32, so its explanation will be omitted.

5, center point O indicates the center point of the first radio wave refraction plate 32. Transmission point T indicates the position of the first transmitting antenna 12 of the first radio station 10 shown in FIG. 2. Reception point R indicates the position of the second receiving antenna 24 of the second radio station 20 shown in FIG. 2. Reception point R' indicates a virtual receiving antenna, which is an extension of a straight line connecting the first transmitting antenna 12 to the center of the first radio wave refraction plate 32 in the example shown in FIG. 2. Specifically, in the example shown in FIG. 5, the straight-line distance between center point O and reception point R is the same as the straight-line distance between center point O and reception point R'. When considering the path of radio waves from transmission point T, passing through points on the first radio wave refraction plate 32, to reception point R, the first radio wave refraction plate 32 is installed in a region where radio waves constructively interact. This enables this embodiment to obtain higher received power. In this embodiment, the region where radio waves constructively interact is called an odd-order Fresnel zone, and the region where radio waves destructively interact is called an even-order Fresnel zone.

As shown in Figure 5, consider a situation in which radio waves from transmission point T pass through first radio wave refraction plate 32 and reach reception point R. In Figure 5, the center point of first radio wave refraction plate 32 is defined as center point O. The straight-line distance between transmission point T and center point O is defined as dTx. The straight-line distance between reception point R and center point O is defined as dRx. Consider a plane P that is perpendicular to the line connecting transmission point T and reception point R', passing through center point O. Now, consider a circle on plane P, centered at center point O, with a radius defined by the following equation (2).

In equation (2), n is a natural number and λ is the wavelength of the radio wave.

In this embodiment, in equation (2), the annular portion ranging from radius rn-1 to radius rn is defined as the nth Fresnel zone. In the example shown in FIG. 5, a first Fresnel zone 50, a second Fresnel zone 52, a third Fresnel zone 54, and a fourth Fresnel zone 56 are shown. For example, the range of a circle with radius r1 is the first Fresnel zone 50. For example, the range of the annular portion between the circle with radius r1 and the circle with radius r2 is the second Fresnel zone 52.

The size of the first radio wave refraction plate 32 is preferably set, for example, to at least twice the radius of the first Fresnel zone 50. The radius of the nth Fresnel zone is also called the nth Fresnel radius. Setting the size of the first radio wave refraction plate 32 to at least twice the first Fresnel radius enables effective wireless communication. The size of the first radio wave refraction plate 32 may be set within a range of ±25% of twice the first Fresnel radius. In other words, the size of the first radio wave refraction plate 32 may be set within a range of 75% to 125% of twice the radius of the first Fresnel zone.

As described above, in the first embodiment, two radio wave refraction plates, the first radio wave refraction plate 32 and the second radio wave refraction plate 34, are installed between the first radio station 10 and the second radio station 20. This enables full-duplex communication to be performed with a short distance, such as within 1 m, between the first transmitting antenna 12 and the first receiving antenna 14, and between the second transmitting antenna 22 and the second receiving antenna 24. In other words, the first embodiment reduces the space required to install the first radio station 10 and the second radio station 20, thereby reducing restrictions on installation locations.

(First Modification of the First Embodiment)
A configuration example of a wireless communication system according to a first modified example of the first embodiment will be described with reference to Fig. 6. Fig. 6 is a diagram showing a configuration example of a wireless communication system according to a first modified example of the first embodiment.

As shown in Figure 6, the wireless communication system 1A includes a first wireless station 10, a second wireless station 20, a first radio wave reflector 62, and a second radio wave reflector 64. Compared to the wireless communication system 1 shown in Figure 2, the wireless communication system 1A includes a first radio wave reflector 62 and a second radio wave reflector 64 instead of the first radio wave refraction plate 32 and the second radio wave refraction plate 34.

The first radio wave reflector 62 and the second radio wave reflector 64 are installed between the first radio station 10 and the second radio station 20. The first radio wave reflector 62 and the second radio wave reflector 64 are configured to reflect and emit received radio waves at a predetermined angle. The first radio wave reflector 62 and the second radio wave reflector 64 may be made of, for example, a metamaterial that changes the phase of the incident wave. The first radio wave reflector 62 and the second radio wave reflector 64 are a type of radio wave control plate.

The first radio wave reflector 62 is installed so that radio waves W1 from the first transmitting antenna 12 are incident on the reflecting surface. The first radio wave reflector 62 is configured to emit radio waves W5, which are the reflected radio waves W1, toward the second wireless station 20. Specifically, the reflection angle θ3 of the first radio wave reflector 62 is configured to be an angle at which radio waves W5 are emitted toward the second receiving antenna 24.

The second radio wave reflector 64 is installed so that radio waves W2 from the second transmitting antenna 22 are incident on the reflecting surface. The second radio wave reflector 64 is configured to emit radio waves W6, which are the reflected radio waves W2, toward the first wireless station 10. Specifically, the reflection angle θ4 of the second radio wave reflector 64 is configured to be an angle at which radio waves W6 are emitted toward the first receiving antenna 14.

The reflection angle θ3 of the first radio wave reflector 62 and the reflection angle θ4 of the second radio wave reflector 64 are types of control angles of the radio wave control plate.

As described above, in the modified example of the first embodiment, two radio wave reflectors, a first radio wave reflector 62 and a second radio wave reflector 64, are installed between the first radio station 10 and the second radio station 20. This allows full-duplex communication to be performed with a short distance, such as within 1 m, between the first transmitting antenna 12 and the first receiving antenna 14, and between the second transmitting antenna 22 and the second receiving antenna 24.

In the present disclosure, the first radio wave refraction plate 32 and the second radio wave refraction plate 34 and the first radio wave reflector 62 and the second radio wave reflector 64 may be selectively used depending on, for example, the installation space. In the following embodiments and variations, each wireless communication system is described as including the first radio wave refraction plate 32 and the second radio wave refraction plate 34, but the present disclosure is not limited to this. Each wireless communication system described below may also include the first radio wave reflector 62 and the second radio wave reflector 64 instead of the first radio wave refraction plate 32 and the second radio wave refraction plate 34.

(Second Modification of the First Embodiment)
2, the first wireless station 10 is described as having the first transmitting antenna 12 and the first receiving antenna 14, and the second wireless station 20 is described as having the second transmitting antenna 22 and the second receiving antenna 24. However, the present disclosure is not limited to this. Specifically, it is sufficient that the transmitting antenna and the receiving antenna are configured separately in at least one of the first wireless station 10 and the second wireless station 20.

Figure 7 is a diagram showing an example configuration of a wireless communication system according to a second variant of the first embodiment. As shown in Figure 7, the wireless communication system 1B includes a first wireless station 10, a second wireless station 20, a first radio wave refraction plate 32, and a second radio wave refraction plate 34. Compared to the wireless communication system 1 shown in Figure 2, the wireless communication system 1B differs in that the second wireless station 20 includes a transmitting/receiving antenna 26 instead of the second transmitting antenna 22 and the second receiving antenna 24.

The transmitting/receiving antenna 26 is an antenna in which a transmitting antenna and a receiving antenna are integrated. When the second wireless station 20 performs full-duplex communication using the transmitting/receiving antenna 26, it has an antenna beam pattern directed in the azimuth direction of the first radio wave refraction plate 32 and the second radio wave refraction plate 34.

As described above, in the second variant of the first embodiment, full-duplex wireless communication can be performed between a first wireless station 10 in which the transmitting antenna and the receiving antenna are configured separately, and a second wireless station 20 in which the transmitting antenna and the receiving antenna are configured integrally.

Second Embodiment
A second embodiment of the present disclosure will be described. As shown in Fig. 2, in the present disclosure, full-duplex wireless communication is performed by installing a first radio wave refraction plate 32 and a second radio wave refraction plate 34 between a first radio station 10 and a second radio station 20. In this case, if the line of sight of the second receiving antenna 24 is good from the first transmitting antenna 12, or if the line of sight of the first receiving antenna 14 is good from the second transmitting antenna 22, direct communication may occur between the antennas, making it impossible to suppress radio wave interference.

An example configuration of a wireless communication system according to the second embodiment will be explained using Figure 8. Figure 8 is a diagram for explaining an example configuration of a wireless communication system according to the second embodiment.

As shown in Figure 8, in the wireless communication system 1C, an obstacle 70 that blocks radio waves is located between the first wireless station 10 and the second wireless station 20.

The first transmitting antenna 12 and the second receiving antenna 24 are installed so that an obstacle 70 is located on the straight line L1 connecting the first transmitting antenna 12 and the second receiving antenna 24. In other words, the first transmitting antenna 12 is installed in a location with poor visibility, such that the second receiving antenna 24 is hidden by the obstacle 70 when viewed from the first transmitting antenna 12. Therefore, in the wireless communication system 1C, direct communication does not occur between the first transmitting antenna 12 and the second receiving antenna 24. This allows the first transmitting antenna 12 and the second receiving antenna 24 to communicate appropriately via the first radio wave refraction plate 32.

The first receiving antenna 14 and the second transmitting antenna 22 are installed so that an obstacle 70 is located on the straight line L2 connecting the first receiving antenna 14 and the second transmitting antenna 22. In other words, the first receiving antenna 14 is installed in a location with poor visibility, such that the second transmitting antenna 22 is hidden by the obstacle 70 when viewed from the first receiving antenna 14. Therefore, in the wireless communication system 1C, direct communication does not occur between the first receiving antenna 14 and the second transmitting antenna 22. As a result, the first receiving antenna 14 and the second transmitting antenna 22 can communicate appropriately via the second radio wave refraction plate 34.

As described above, the second embodiment can prevent direct communication between the first transmitting antenna 12 and the second receiving antenna 24, and between the first receiving antenna 14 and the second transmitting antenna 22. This allows the second embodiment to more appropriately suppress radio wave interference when performing full-duplex communication.

(Modification of the second embodiment)
A modified example of the second embodiment will be described. In the second embodiment, the first transmitting antenna 12 is installed in a position where the second receiving antenna 24 has poor visibility when viewed from the first transmitting antenna 12. In the second embodiment, the first receiving antenna 14 is installed in a position where the second transmitting antenna 22 has poor visibility when viewed from the first receiving antenna 14. In this case, if the distance between the first radio wave refraction plate 32 and the second radio wave refraction plate 34 is smaller than the distance between the first transmitting antenna 12 and the first receiving antenna 14 and the distance between the second transmitting antenna 22 and the second receiving antenna 24, there is a possibility of self-interference.

For this reason, it is preferable that the first radio wave refraction plate 32 and the second radio wave refraction plate 34 are set so that the distance between the center of the refraction surface of the first radio wave refraction plate 32 and the center of the refraction surface of the second radio wave refraction plate 34 is larger than the distance between the first transmitting antenna 12 and the first receiving antenna 14. It is preferable that the first radio wave refraction plate 32 and the second radio wave refraction plate 34 are installed so that the distance between the center of the refraction surface of the first radio wave refraction plate 32 and the center of the refraction surface of the second radio wave refraction plate 34 is larger than the distance between the second transmitting antenna 22 and the second receiving antenna 24.

The distance between the first transmitting antenna 12 and the first receiving antenna 14, and the distance between the second transmitting antenna 22 and the second receiving antenna 24, is, for example, within 1 m. In this case, it is preferable to install the first radio wave refraction plate 32 and the second radio wave refraction plate 34 at a distance such that the distance between the center of the refraction surface of the first radio wave refraction plate 32 and the center of the refraction surface of the second radio wave refraction plate 34 is, for example, 10 m or more. This allows the azimuth angles of the radio waves W1 transmitted by the first transmitting antenna 12 and the radio waves W2 transmitted by the second transmitting antenna 22 to be spaced apart from the directions of the second receiving antenna 24 and the first receiving antenna 14, respectively, thereby further suppressing radio wave interference.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the content of these embodiments. Furthermore, the components described above include those that would be easily imagined by a person skilled in the art, those that are substantially identical, and those that are within the scope of what is known as equivalents. Furthermore, the components described above can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiments.

REFERENCE SIGNS LIST 1 wireless communication system 10 first wireless station 12 first transmitting antenna 14 first receiving antenna 20 second wireless station 22 second transmitting antenna 24 second receiving antenna 26 transmitting/receiving antenna 32 first radio wave refraction plate 34 second radio wave refraction plate 62 first radio wave reflector 64 second radio wave reflector

Claims (2)

a first radio station having a first transmitting/receiving antenna;
a second radio station having a second transmitting/receiving antenna;
a first radio wave control board that is installed between the first radio station and the second radio station, receives radio waves transmitted from the first transmitting/receiving antenna, and transmits the radio waves to the second transmitting/receiving antenna ;
a second radio wave control board that is installed between the first radio station and the second radio station, receives radio waves transmitted from the second transmitting/receiving antenna, and transmits the radio waves to the first transmitting/receiving antenna ;
Including,
At least the first transmitting/receiving antenna is configured as a transmitting antenna and a receiving antenna separately.
Wireless communication system. receiving radio waves transmitted from a transmitting antenna of a first radio station with a first radio wave control board, and emitting the radio waves at a predetermined control angle so that the radio waves are received by a transmitting/receiving antenna of a second radio station;
receiving the radio wave transmitted from the transmitting/receiving antenna of the second radio station with a second radio wave control board, and emitting the radio wave at a predetermined control angle so that the receiving antenna of the first radio station receives the radio wave;
A wireless communication method comprising: