Transmission device

Abstract

A transmission device according to the present invention includes: a beam generation unit that generates an Airy beam having a property in which radio waves are spatially asymmetric; and a control unit that performs spatial modulation of a carrier wave by controlling a phase pattern such that spatial distribution of the Airy beam generated by the beam generation unit is different.　

Description

Transmitting device

[0001] The present invention relates to a transmitting device.

[0002] Conventionally, in order to realize high-speed and large-capacity transmission, the use of wireless communication using high frequency bands such as millimeter waves, sub-THz waves, and terahertz (THz) waves has been considered. In addition, in high frequency bands such as sub-THz waves, efforts have been made to suppress interference by using an Airy beam, which has the characteristic of radio waves being spatially asymmetric (see, for example, Patent Document 1 and Non-Patent Document 1).

[0003] International Publication No. 2022 / 145008

[0004] Doohwan Lee, Yasunori Yagi, and Hiroyuki Shiba, “Multishape radio: new approach to utilizing the physical properties of electromagnetic waves”, IEICE Communications Express, Vol.11, No.9, 571-576.

[0005] In the wireless communication using the above-mentioned high frequency band, the power consumption of RF (Radio Frequency) components constituting the wireless device, such as an up-converter and a down-converter, is large due to the use of the high frequency band. Furthermore, when modulation and demodulation with a high modulation depth are used, a high-precision RF device is required, which results in a complex circuit. Thus, conventional communication devices that perform wireless communication using the high frequency band have had problems of high power consumption and a complex configuration.

[0006] In view of the above circumstances, an object of the present invention is to provide a technology that enables a communication device that performs wireless communication using a high frequency band to have a simple configuration and low power consumption.

[0007] One aspect of the present invention is a transmitting device comprising a beam generating unit that generates an Airy beam whose radio waves have the property of being spatially asymmetric, and a control unit that performs spatial modulation of a carrier wave by controlling a phase pattern so that the spatial distribution of the Airy beam generated by the beam generating unit differs.

[0008] According to the present invention, it is possible to provide a communication device that performs wireless communication using a high frequency band with a simple configuration and low power consumption.

[0009] FIG. 1 is a diagram illustrating an example of the configuration of a communication system in an embodiment. FIG. 2 is a diagram illustrating details of a plurality of receiving units in an embodiment. FIG. 3 is a diagram illustrating a modulation method performed by a transmitting device in an embodiment. FIG. 4 is a diagram illustrating a modulation method performed by a transmitting device in an embodiment. FIG. 5 is a diagram illustrating a modulation method performed by a transmitting device in an embodiment. FIG. 6 is a diagram illustrating a specific example of application example 1. FIG. 7 is a diagram illustrating a specific example of application example 2. FIG. 8 is a diagram illustrating a specific example of application example 3. FIG. 9 is a diagram illustrating a specific example of application example 3.

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] 1 is a diagram showing an example of the configuration of a communication system 100 according to an embodiment. The communication system 100 includes a transmitting device 10 and a receiving device 20. The transmitting device 10 and the receiving device 20 perform wireless communication using a high frequency band. Here, the high frequency band refers to frequency bands such as millimeter waves, sub-THz waves, and terahertz waves (THz).

[0012] The transmitting device 10 is a device that transmits data to be transmitted (hereinafter referred to as "transmission data") using a high frequency band. The transmitting device 10 wirelessly transmits the transmission data to the receiving device 20 using an Airy beam. An Airy beam is characterized by radio waves that are spatially asymmetric. In other words, an Airy beam is characterized by asymmetric side lobes. Based on this characteristic, the transmitting device 10 of the present invention performs modulation using the distribution of the radio waves of the Airy beam.

[0013] For example, the transmitting device 10 can generate Airy beams with different radio wave radiation directions by rotating the phase pattern set on the lens used to generate the Airy beam. That is, the transmitting device 10 can generate multiple Airy beams with side lobes pointing in different directions by rotating the phase pattern set on the lens used to generate the Airy beam. The phase pattern set on the lens is a phase pattern that can generate an Airy beam. This enables the transmitting device 10 to perform modulation using Airy beams with different radio wave radiation directions. The method of rotating the phase pattern set on the lens may involve physically rotating the lens. Alternatively, the lens may be composed of multiple phase-controllable elements, and the phase may be set using a method in which the phase of each element is set to be the same as when the lens is physically rotated.

[0014] The receiving device 20 receives the radio waves transmitted from the transmitting device 10. The receiving device 20 demodulates the signal based on the received radio waves. Specifically, the receiving device 20 detects the spatial distribution based on the intensities of the main lobe and side lobes of the received radio waves (Airy beam) and demodulates the signal.

[0015] [Configuration of Transmitting Device 10] Next, we will explain the configurations of the transmitting device 10 and the receiving device 20. First, we will explain the configuration of the transmitting device 10. The transmitting device 10 includes a carrier wave generating unit 11, a signal generating unit 12, a control unit 13, and a beam forming unit 14.

[0016] The carrier wave generation unit 11 generates a carrier wave. The carrier wave generation unit 11 outputs the generated carrier wave as a radio wave to the beam generation unit 14. The signal generation unit 12 generates transmission data. The signal generation unit 12 outputs the generated transmission data to the control unit 13 and the beam generation unit 14.

[0017] The control unit 13 sets a phase pattern for generating an Airy beam in the beam generation unit 14. Furthermore, the control unit 13 performs spatial modulation of the carrier wave by controlling the phase pattern set in the beam generation unit 14 so that the spatial distribution of the Airy beam varies. Specifically, the control unit 13 adjusts the radio waves of the Airy beam generated by the beam generation unit 14 by rotating the phase pattern of a lens provided in the beam generation unit 14. Adjusting the radio waves of the Airy beam means adjusting the radiation direction of the radio waves of the Airy beam. The control unit 13 adjusts the rotation angle of the phase pattern of the lens based on the transmission data.

[0018] The beam generator 14 generates an Airy beam for transmitting transmission data based on the carrier wave output from the carrier wave generator 11 and the transmission data output from the signal generator 12. The beam generator 14 is composed of a phase setting lens 141 and a Fourier lens 142. The phase setting lens 141 is composed of a mechanism capable of rotating a phase pattern. Here, the mechanism capable of rotating a phase pattern is, for example, a metasurface. The phase setting lens 141 forms a phase pattern set by the controller 13 at a predetermined rotation angle. The phase pattern set in the phase setting lens 141 is calculated based on the following equation (1). In equation (1), β represents a scaling parameter, i represents an imaginary number, and k ｘ , k ｙ represents the xy coordinate system, and α is a constant. ｘ , k ｙ )=(0,0). Details of equation (1) are described in Non-Patent Document 1, and therefore will not be described here.

[0019]

[0020] The Fourier lens 142 is set to a phase pattern obtained by modulo calculating the phase of the convex lens by 360. The phase pattern of the Fourier lens 142 may be set in advance.

[0021] In the transmitting device 10, the carrier wave output from the carrier wave generating unit 11 passes through the beam generating unit 14. Here, a phase pattern is set in the beam generating unit 14 so that an Airy beam can be generated. The control unit 13 rotates the phase pattern set in the phase setting lens 141 provided in the beam generating unit 14 in accordance with the transmission data, thereby performing spatial modulation of the transmission data.

[0022] [Configuration of Receiving Device 20] Next, the configuration of the receiving device 20 will be described. The receiving device 20 includes a plurality of receiving units 21 and a signal demodulation unit 22. The plurality of receiving units 21 receive radio waves transmitted from the transmitting device 10 and detect the intensity of the received radio waves. The signal demodulation unit 22 calculates the distribution of Airy beams based on the intensity of the radio waves detected by each receiving unit 21 and performs demodulation processing.

[0023] 2 is a diagram showing the details of the multiple receiving units 21 in this embodiment. As shown in FIG. 2, the receiving units 21 are arranged in an array of M rows and N columns. Each receiving unit 21 includes an antenna 23 and a measuring unit 24. The antenna 23 receives radio waves transmitted from the transmitting device 10. The measuring unit 24 detects the intensity of the received radio waves. In this way, the receiving device 20 does not need to detect the phase, which requires high precision, and only detects the intensity, allowing for simplification of the device.

[0024] Next, the modulation method performed by the transmitting device 10 will be described. Figures 3 to 6 are diagrams for explaining the modulation method performed by the transmitting device 10 in the embodiment. Figure 3 shows the phase pattern and spatial distribution when modulating "00" in the transmission data. Figure 4 shows the phase pattern and spatial distribution when modulating "11" in the transmission data. Figure 5 shows the phase pattern and spatial distribution when modulating "01" in the transmission data. Figure 6 shows the phase pattern and spatial distribution when modulating "10" in the transmission data.

[0025] When modulating "00" in the transmission data, the control unit 13 sets the phase pattern of the phase setting lens 141 to the state shown in Fig. 3(A). Hereinafter, the phase pattern of the phase setting lens 141 in the state shown in Fig. 3(A) is also referred to as the reference pattern. The reference pattern is the state in which the phase pattern is not rotated. When the phase setting lens 141 is in the state shown in Fig. 3(A), the distribution of the radio waves of the Airy Beam generated is as shown in Fig. 3(B).

[0026] When modulating "11" in the transmission data, the control unit 13 sets the phase pattern of the phase setting lens 141 to the state shown in FIG. 4A. The state shown in FIG. 4A is a state in which the phase pattern is rotated 180 degrees from the reference pattern state. This is a state in which the phase setting lens 141 is rotated 180 degrees clockwise around the center. In other words, when modulating "11" in the transmission data, the control unit 13 rotates the phase pattern of the phase setting lens 141 180 degrees from the reference pattern state. The distribution of the radio waves of the Airy Beam generated when the phase setting lens 141 is in the state shown in FIG. 4A is as shown in FIG. 4B.

[0027] When modulating "01" in the transmission data, the control unit 13 sets the phase pattern of the phase setting lens 141 to the state shown in FIG. 5A. The state shown in FIG. 5A is a state in which the phase pattern is rotated 45 degrees from the reference pattern state. This is a state in which the phase setting lens 141 is rotated 45 degrees clockwise around the center. In other words, when modulating "01" in the transmission data, the control unit 13 rotates the phase pattern of the phase setting lens 141 45 degrees from the reference pattern state. The distribution of the Airy Beam radio waves generated when the phase setting lens 141 is in the state shown in FIG. 5A is as shown in FIG. 5B.

[0028] When modulating "10" in the transmission data, the control unit 13 sets the phase pattern of the phase setting lens 141 to the state shown in FIG. 6A. The state shown in FIG. 6A is a state in which the phase pattern is rotated 135 degrees from the reference pattern state. This is a state in which the phase setting lens 141 is rotated 135 degrees clockwise around the center. In other words, when modulating "10" in the transmission data, the control unit 13 rotates the phase pattern of the phase setting lens 141 135 degrees from the reference pattern state. The distribution of the radio waves of the Airy Beam generated when the phase setting lens 141 is in the state shown in FIG. 6A is as shown in FIG. 6B.

[0029] As shown in Figures 3 to 6, the spatial distribution of the Airy beam changes by rotating the phase pattern set in the phase setting lens 141. The transmitter 10 uses this feature to spatially modulate the carrier wave. Note that the rotation angle of the phase pattern during modulation described above is an example, and the orientation of the phase pattern during modulation (rotation angle of the phase pattern) is not limited to the above. For example, the state shown in Figure 4(A) may be a reference pattern used when modulating "00" in the transmission data, and the state shown in Figure 3(A) may be used when modulating "11" in the transmission data. Note that the modulation depth can also be increased by making the rotation pattern of the phase pattern finer.

[0030] According to the communication system 100 configured as described above, the transmitting device 10 includes a beam generating unit 14 that generates an Airy beam having the property of making radio waves spatially asymmetric, and a control unit 13 that performs spatial modulation of the carrier wave by controlling the phase pattern so that the spatial distribution of the Airy beam varies. Specifically, the control unit 13 of the transmitting device 10 performs spatial modulation of the carrier wave by controlling the rotation of the phase pattern for generating the Airy beam.

[0031] This allows a communication device that performs wireless communication using a high frequency band to have a simple configuration and low power consumption. Specifically, the transmitter 10 performs modulation using the distribution of radio waves of an Airy beam. This allows the transmitter 10 to eliminate components that modulate and upconvert the modulated signal. As a result, the power consumption of RF components can be reduced and the device configuration can be simplified compared to conventional device configurations.

[0032] The receiver 20 does not perform highly accurate phase detection, but only performs simple intensity detection, thereby simplifying the device. In this way, the communication system 100 performs modulation and demodulation using the spatial characteristics of the Airy beam, enabling desired wireless communication with low power consumption and a simple device configuration, without using conventional modulators and demodulators.

[0033] Next, an application example using the above-described transmitting device 10 will be described.

[0034] (Application Example 1) Consider a case where there is an obstacle on the communication path between a transmitter and a receiver. Since high-frequency bands tend to travel in a straight line, if there is an obstacle on the communication path between the transmitter and the receiver, there is a high possibility that the radio waves transmitted from the transmitter will be blocked by the obstacle. In such a case, it is expected that the receiver will not be able to receive the radio waves properly.

[0035] In contrast, the transmitter 10 of the present invention generates an Airy beam so that the side lobes point in a direction different from the direction of the obstacle, enabling communication while avoiding the obstacle. For example, the transmitter 10 generates an Airy beam by fixing the phase pattern so that the side lobes point in the direction of the obstacle. Figures 7 and 8 are diagrams showing a specific example of Application Example 1. As shown in Figure 7, if an obstacle T is located below a reference line BL on the communication path between the transmitter 10 and the receiver 20, the transmitter 10 can avoid the obstacle by rotating the phase pattern so as not to generate an Airy beam that radiates radio waves in a direction below (lower than) the reference line BL. That is, the transmitter 10 can avoid the obstacle by rotating the phase pattern so as not to generate an Airy beam whose side lobes point in a direction below (lower than) the reference line BL. Note that the transmitter 10 modulates the signal itself to be carried on the generated Airy beam using a conventional modulation method. The reference line BL may be predetermined based on the positional relationship between the transmitter 10 and the receiver 20.

[0036] 8, when an obstacle T is located above a reference line BL on the communication path between the transmitting device 10 and the receiving device 20, the transmitting device 10 can avoid the obstacle by rotating the phase pattern so as not to generate an Airy beam that radiates radio waves in a direction above (higher than) the reference line BL. In other words, the transmitting device 10 can avoid the obstacle by rotating the phase pattern so as not to generate an Airy beam whose side lobes are directed in a direction above (higher than) the reference line BL.

[0037] Note that the user may visually determine whether the obstacle T is above or below the reference line BL. Although not shown in FIGS. 7 and 8 , it is also possible that the obstacle T is located on the left or right side of the communication path between the transmitting device 10 and the receiving device 20. In this case, the transmitting device 10 may generate an Airy beam (an Airy beam with side lobes pointing in a direction different from the direction in which the obstacle exists) that can radiate radio waves. In this way, the transmitting device 10 can be controlled to avoid the obstacle.

[0038] (Application Example 2) Consider a case where an eavesdropper U eavesdrops on communication between a transmitting device and a receiving device. In general communication, once communication between a transmitting device and a receiving device is eavesdropped, there is a possibility that eavesdropping will continue. In contrast, the transmitting device 10 of the present invention continuously rotates the phase pattern to avoid eavesdropping and enable secure communication.

[0039] FIG. 9 is a diagram illustrating a specific example of Application Example 2. As illustrated in FIG. 9 , assume that the transmitting device 10 generates an Airy beam that radiates radio waves in directions indicated by spatial distributions P1, P2, P3, and P4. For example, the transmitting device 10 generates an Airy beam that radiates radio waves in the direction indicated by spatial distribution P1, and then rotates the phase pattern to generate an Airy beam that radiates radio waves in the direction indicated by spatial distribution P2. Similarly, the transmitting device 10 generates an Airy beam that radiates radio waves in the direction indicated by spatial distribution P2, and then rotates the phase pattern to generate an Airy beam that radiates radio waves in the direction indicated by spatial distribution P3. Similarly, the transmitting device 10 generates an Airy beam that radiates radio waves in the direction indicated by spatial distribution P4, and then rotates the phase pattern to generate an Airy beam that radiates radio waves in the direction indicated by spatial distribution P4.

[0040] By continuously rotating the phase pattern in this way, the receiving device 20 can continuously receive the transmitted data with strong power. On the other hand, since the power of the Airy beam transmitted from the transmitting device 10 fluctuates at the eavesdropper U, it is impossible to receive anything other than the Airy beam radiating radio waves in the direction of the eavesdropper U. In this way, secure communication is possible.

[0041] (Application Example 3) Consider a case where transmission data is transmitted to either a receiving device located in the sky or a receiving device located on the ground. When the transmission data is transmitted to the receiving device located in the sky, the transmission data may become an interference signal for the receiving device located on the ground. Conversely, when the transmission data is transmitted to the receiving device located on the ground, the transmission data may become an interference signal for the receiving device located in the sky.

[0042] In contrast, the transmitting device 10 of the present invention generates an Airy beam that can radiate radio waves in the direction of the receiving device that is the destination of the transmitted data, thereby enabling communication while suppressing interference. For example, the transmitting device 10 generates an Airy beam by fixing a phase pattern so that a side lobe is oriented in the direction of the receiving device that is the destination of the transmitted data. Figures 10 and 11 are diagrams showing a specific example of Application Example 3. In Figures 10 and 11, the receiving device 20 is a receiving device located in the sky (for example, a flying object such as a drone), and the receiving device 30 is a receiving device located on the ground.

[0043] 10, when receiving device 20 is the receiving device to which transmission data is to be sent, transmitting device 10 generates an Airy beam that radiates radio waves in the direction (sky) where receiving device 20 is located, and rotates the phase pattern so as not to generate an Airy beam that radiates radio waves in the direction (ground) where receiving device 30 is located. In this way, transmitting device 10 can avoid interference with receiving device 30 by rotating the phase pattern to generate an Airy beam whose side lobes are directed in the direction (sky) where receiving device 20 is located. Note that transmitting device 10 modulates the signal itself to be carried on the generated Airy beam using a conventional modulation method.

[0044] 11 , when receiving device 30 is the receiving device to which transmission data is to be sent, transmitting device 10 generates an Airy beam that radiates radio waves in the direction (ground) where receiving device 30 is located, and rotates the phase pattern so as not to generate an Airy beam that radiates radio waves in the direction (sky) where receiving device 20 is located. In this way, transmitting device 10 can avoid interference with receiving device 20 by rotating the phase pattern to generate an Airy beam whose side lobes are directed in the direction (ground) where receiving device 30 is located. In this way, transmitting device 10 can perform control to suppress spatial interference.

[0045] A part (e.g., the control unit 13) or all of the transmitting device 10 in the above-described embodiment may be implemented by a computer. In this case, a program for implementing this function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read and executed by a computer system. Note that the term "computer system" here includes hardware such as an OS (Operating System) and peripheral devices.

[0046] Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs (Read Only Memory), and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, the term "computer-readable recording medium" may also include devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs over networks like the Internet or communication lines like telephone lines, and devices that store programs for a fixed period of time, such as volatile memory within the computer systems that serve as servers or clients in such cases. The above programs may also be recorded on computer-readable recording media. Examples of computer-readable recording media include portable media such as flexible disks, magneto-optical disks, ROMs, CD-ROMs, and semiconductor storage devices (e.g., solid-state drives (SSDs)), as well as storage devices such as hard disks and semiconductor storage devices built into computer systems. The above programs may also be transmitted via telecommunications lines.

[0047] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0048] The present invention can be applied to wireless communication technology using high frequency bands.

[0049] REFERENCE SIGNS LIST 10... transmitting device, 11... carrier wave generating unit, 12... signal generating unit, 13... control unit, 14... beam generating unit, 20... receiving device, 21... receiving unit, 22... signal demodulating unit, 23... antenna, 24... measuring unit, 100... communication system, 141... phase setting lens, 142... Fourier lens

Claims

1. A transmitting device comprising: a beam generating unit that generates an Airy beam, which has the property of making radio waves spatially asymmetric; and a control unit that performs spatial modulation of a carrier wave by controlling the phase pattern so that the spatial distribution of the Airy beam generated by the beam generating unit differs.

2. The transmitting device according to claim 1, wherein the control unit performs spatial modulation of the carrier wave by controlling the rotation of the phase pattern.

3. A transmitting device as described in claim 1 or 2, wherein the beam generating unit is composed of a plurality of lenses for generating the Airy beam, and the control unit performs spatial modulation of the carrier wave by rotating the phase patterns of some of the plurality of lenses in accordance with the transmission data.

4. The transmitting device according to claim 3, wherein the part of the lenses is made of a metasurface material.

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