Transmission device and transmission method

Abstract

This transmission device comprises: a signal generation unit for generating signals in -n-th order (n is an integer of 1 or greater) to 0-th order orbital angular momentum modes; a signal transmission unit for transmitting a multiplexed signal obtained by multiplexing the signals in the -n-th order to 0-th order orbital angular momentum modes generated by the signal generation unit; and a phase control unit for performing phase control for increasing, by a prescribed amount, all the orders of the orbital angular momentum mode signals multiplexed into the multiplexed signal transmitted by the signal transmission unit.

Description

Transmitting device and transmitting method

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

[0002] Conventionally, a technique for changing the phase of a radio signal when transmitting the signal from a transmitting device to a receiving device has been known (for example, Non-Patent Document 1). Also conventionally, a technique for transmitting an OAM (Orbital Angular Momentum) mode signal from a transmitting device to a receiving device has been known, and is used to transmit a large amount of data from a transmitting device to a receiving device.

[0003] S. Abdollahramezani et al., “Electrically driven reprogrammable phase-change metasurface reaching 80% efficiency”, Nature Communications, 13, Article number: 1696 (2022).

[0004] However, in the past, when multiple signals of different orders of OAM modes were transmitted from a transmitting device to a receiving device, and if the OAM mode signals contained higher-order mode signals, the variation in the multiple OAM mode signals increased, and communication quality could deteriorate when long-distance transmission was performed over a large distance between the transmitting device and the receiving device.

[0005] In view of the above circumstances, the present invention aims to provide a technology that can prevent variations in signals transmitted from a transmitting device to a receiving device, even when a higher-order mode signal is included in an OAM (orbital angular momentum) mode signal, and that enables long-distance transmission.

[0006] One aspect of the present invention is a transmitting device including: a signal generating unit that generates orbital angular momentum mode signals of -nth order (n is an integer equal to or greater than 1) to 0th order; a signal transmitting unit that transmits a multiplexed signal in which the orbital angular momentum mode signals of -nth order to 0th order generated by the signal generating unit are multiplexed; and a phase control unit that performs phase control to increase, by a predetermined amount, all orders of the orbital angular momentum mode signals multiplexed into the multiplexed signal transmitted by the signal transmitting unit.

[0007] Another aspect of the present invention is a transmission method including: a signal generation process for generating orbital angular momentum mode signals of −nth order (n is an integer of 1 or more) to 0th order; a signal transmission process for transmitting a multiplexed signal in which the orbital angular momentum mode signals of −nth order to 0th order generated in the signal generation process are multiplexed; and a phase control process for performing phase control to increase, by a predetermined amount, all orders of the orbital angular momentum mode signals multiplexed in the multiplexed signal transmitted in the signal transmission process.

[0008] According to the present invention, even if a higher-order mode signal is included in an OAM (orbital angular momentum) mode signal, it is possible to prevent variations from occurring in the signal transmitted from the transmitting device to the receiving device, thereby enabling long-distance transmission.

[0009] FIG. 1 is a schematic configuration diagram of a communication system according to a first embodiment of the present invention. FIG. 2 is a schematic configuration diagram showing an example of a transmitting antenna according to the first embodiment of the present invention. FIG. 3 is a schematic configuration diagram showing another example of a transmitting antenna according to the first embodiment of the present invention. FIG. 4 is a flowchart showing processing of a transmitting device according to the first embodiment of the present invention. FIG. 5 is a diagram showing an overview of transmission processing by the transmitting device according to the first embodiment of the present invention. FIG. 6 is a table explaining an example of signal generation processing of a signal generation unit according to the first embodiment of the present invention. FIG. 7 is a diagram showing an example of an OAM mode conversion correspondence table stored in a transmitting device storage unit according to the first embodiment of the present invention. FIG. 8 is a table explaining an example of phase control processing of a phase control unit according to the first embodiment of the present invention. FIG. 9 is a schematic configuration diagram of a communication system according to a second embodiment of the present invention. FIG. 10 is a flowchart showing processing of a transmitting device according to the second embodiment of the present invention. FIG. 11 is a diagram showing an overview of transmission processing by the transmitting device according to the second embodiment of the present invention.

[0010] First and second embodiments of the present invention will be described below with reference to the drawings. First, the first embodiment of the present invention will be described.

[0011] 1 is a schematic diagram of a communication system 100a according to a first embodiment of the present invention. The communication system 100a includes a transmitting device 10a and a receiving device 20. The transmitting device 10a includes a transmitting device control unit 11a, a transmitting device storage unit 12a, a signal generation unit 13a, a signal transmitting unit 14a, a transmitting antenna 15a, a phase control unit 16a, and a transmission plate 17a.

[0012] The transmitting device control unit 11a includes a CPU (Central Processing Unit) and the like. The transmitting device control unit 11a is connected to a transmitting device storage unit 12a, a signal generation unit 13a, a signal transmission unit 14a, and a phase control unit 16a. The transmitting device control unit 11a controls each unit of the transmitting device 10a. The transmitting device storage unit 12a includes a memory, an HDD (Hard Disk Drive), and the like. The transmitting device storage unit 12a is connected to the transmitting device control unit 11a. The transmitting device storage unit 12a stores data necessary for the operation of the transmitting device 10a, data to be transmitted from the transmitting device 10a to the receiving device 20, and the like.

[0013] The signal generator 13a is connected to the transmitter control unit 11a and the signal transmitter 14a. The signal generator 13a generates a plurality of signals of different orders in Orbital Angular Momentum (OAM) mode to be transmitted from the transmitter 10a to the receiver 20. Note that OAM is one of the characteristics of electromagnetic waves and represents the degree of electromagnetic wave rotation, which forms a spiral shape relative to the direction of propagation of the electromagnetic wave. Specifically, OAM is expressed as a rotation of the phase on a plane perpendicular to the direction of propagation of the electromagnetic wave. Electromagnetic waves with different OAM are uncorrelated, so they can be distinguished and separated even when superimposed.

[0014] The signal transmitting unit 14a is connected to the transmitting device control unit 11a, the signal generating unit 13a, and the transmitting antenna 15a. The signal transmitting unit 14a performs encoding processing, modulation processing, etc. on the signal transmitted from the transmitting device 10a to the receiving device 20. The transmitting antenna 15a is connected to the signal transmitting unit 14a. The transmitting antenna 15a transmits the signal output from the signal transmitting unit 14a as a wireless signal.

[0015] FIG. 2 is a schematic diagram showing an example of a transmitting antenna 15a according to the first embodiment of the present invention. FIG. 2 illustrates a case in which the transmitting antenna 15a is a uniform circular array (UCA) antenna. A circular array is an antenna array in which identical sensor elements are arranged at equal intervals on a circumference. Circular arrays are used to radiate radio waves. The antenna elements constituting the circular array radiate electromagnetic waves in the same direction. The radio waves radiated in the axial direction of the entire circular array are multiplexed. In a circular array, different modes (phase patterns) can be generated by adjusting the feed phases of the antenna elements, enabling multiplexed transmission.

[0016] 2, the transmitting antenna 15a is shown as having eight antenna elements 151a, 152a, 153a, 154a, 155a, 156a, 157a, and 158a arranged at equal intervals on the circumference of a predetermined circle. While FIG. 2 illustrates the transmitting antenna 15a as having eight antenna elements 151a, 152a, 153a, 154a, 155a, 156a, 157a, and 158a arranged at equal intervals on the circumference of a predetermined circle, the present invention is not limited to this. For example, if the number of antenna elements constituting the transmitting antenna 15a is k, k does not have to be 8 as shown in FIG. 2 as long as k is an integer equal to or greater than 2. In addition, if the order of the OAM mode signal transmitted by the transmitting antenna 15a is l and the antenna number of the antenna elements that make up the transmitting antenna 15a is k, the phase distribution of each antenna element 151a, 152a, 153a, 154a, 155a, 156a, 157a, and 158a is expressed as 2πl / k.

[0017] 2, the transmitting antenna 15a according to the first embodiment of the present invention is configured as a circular array antenna, but the present invention is not limited to this. For example, the transmitting antenna 15a according to the first embodiment of the present invention may be configured as a double circular array antenna as shown in FIG.

[0018] 3, the transmitting antenna 15a shows eight antenna elements 1511a, 1512a, 1513a, 1514a, 1515a, 1516a, 1517a, and 1518a arranged at equal intervals on the circumference of a predetermined inner circle, and also shows eight antenna elements 1521a, 1522a, 1523a, 1524a, 1525a, 1526a, 1527a, and 1528a arranged at equal intervals on the circumference of a predetermined outer circle.

[0019] 3 illustrates a case in which the transmitting antenna 15a includes eight antenna elements 1511a, 1512a, 1513a, 1514a, 1515a, 1516a, 1517a, and 1518a arranged at equal intervals on the circumference of a predetermined inner circle, and eight antenna elements 1521a, 1522a, 1523a, 1524a, 1525a, 1526a, 1527a, and 1528a arranged at equal intervals on the circumference of a predetermined outer circle, but the present invention is not limited to this. For example, the number of antenna elements constituting the transmitting antenna 15a illustrated in FIG. 3 may be less than or greater than 16.

[0020] By using the configuration of the transmitting antenna 15a shown in Fig. 3, more data can be transmitted from the transmitting device 10a to the receiving device 20 than when using the configuration of the transmitting antenna 15a shown in Fig. 2. Note that Fig. 3 illustrates the case where the antenna elements constituting the transmitting antenna 15a are arranged on the circumference of two circles, but this is not limitative. For example, the antenna elements constituting the transmitting antenna 15a may be arranged on the circumference of N circles (N is an integer equal to or greater than 3).

[0021] Returning to the explanation of FIG. 1 , the phase control section 16a is connected to the transmitter control section 11a and the transmission plate 17a. The phase control section 16a includes a RIS (Reconfigurable Intelligent Surface). The RIS used in the first embodiment is a planar surface made up of unit cells, and its characteristics are dynamically controlled to adjust the phase of the OAM mode signal transmitted through the transmission plate 17a. The transmission plate 17a is a transparent plate-shaped member. The RIS constituting the phase control section 16a is attached to one surface of the transmission plate 17a.

[0022] 1 includes a receiving device control unit 21, a receiving device storage unit 22, a receiving antenna 23, and a signal receiving unit 24. The receiving device control unit 21 includes a CPU (Central Processing Unit) and the like. The receiving device control unit 21 is connected to the receiving device storage unit 22 and the signal receiving unit 24. The receiving device control unit 21 controls each unit of the transmitting device 10. The receiving device storage unit 22 includes a memory, an HDD (Hard Disk Drive), and the like. The receiving device storage unit 22 is connected to the receiving device control unit 21. The receiving device storage unit 22 stores data necessary for the operation of the receiving device 20, data that the receiving device 20 receives from the transmitting device 10a, and the like.

[0023] The receiving antenna 23 is connected to the signal receiving unit 24. The receiving antenna 23 receives a signal transmitted from the transmitting device 10a and outputs the signal to the signal receiving unit 24. The signal receiving unit 24 is connected to the receiving device control unit 21 and the receiving antenna 23. The signal receiving unit 24 performs decoding processing, demodulation processing, etc. on the signal transmitted from the transmitting device 10a to the receiving device 20.

[0024] Fig. 4 is a flowchart showing the processing of the transmitting device 10a according to the first embodiment of the present invention. Fig. 5 is a diagram showing an outline of the transmission processing by the transmitting device 10a according to the first embodiment of the present invention. First, in the flowchart shown in Fig. 4, the signal generating unit 13a generates signals in multiple OAM (orbital angular momentum) modes (step S11). For example, as shown in Fig. 6, when the OAM mode is 0, the signal generating unit 13a generates OAM mode signals with phases of 0, 0, 0, 0 for antenna elements identified by antenna element numbers 1, 2, 3, and 4.

[0025] 6, when the OAM mode is -1, the signal generation unit 13a generates OAM mode signals with phases of 0, -π / 2, -π, and -3π / 2 for the antenna elements identified by the antenna element numbers 1, 2, 3, and 4. When the OAM mode is -2, the signal generation unit 13a generates OAM mode signals with phases of 0, -π, 0, and -π for the antenna elements identified by the antenna element numbers 1, 2, 3, and 4.

[0026] Next, in the flowchart shown in Fig. 4, the signal generating unit 13a generates a multiplexed signal by multiplexing the multiple OAM mode signals generated in step S11 (step S12). Next, in the flowchart shown in Fig. 4, the signal transmitting unit 14a transmits the multiplexed signal generated in step S12 via the transmitting antenna 15a as a spiral OAM mode signal D11 as shown in Fig. 5 (step S13).

[0027] Next, in the flowchart shown in FIG. 4, the phase control unit 16a determines whether the transmission plate 17a has received a multiplexed signal (step S14). If the transmission plate 17a determines that it has not received a multiplexed signal (NO in step S14), the phase control unit 16a performs the process of step S14 again after a predetermined time has elapsed. On the other hand, if the transmission plate 17a determines that it has received a multiplexed signal (YES in step S14), the phase control unit 16a performs phase control on the multiplexed signal received by the transmission plate 17a using RIS technology (step S15). Specifically, the phase control unit 16a converts the OAM mode so that the smallest order (order -2 in FIG. 6) among the orders of the multiple OAM mode signals generated by the signal generation unit 13a (see FIG. 6) becomes 0.

[0028] The transmitter storage unit 12a of the transmitter 10a stores data of an OAM mode conversion correspondence table such as that shown in FIG. 7, and based on this OAM mode conversion correspondence table, the phase control unit 16a increases the order of the OAM mode signal generated by the signal generation unit 13a (that is, the order of the OAM mode signal received by the transmission plate 17a) by a predetermined order (here, the order such that the smallest order, −2, of the orders of the OAM mode signals received by the transmission plate 17a becomes zero (here, +2)). Here, all of the orders of −2, −1, and 0 of the OAM mode signals generated by the signal generation unit 13a are increased by the predetermined order (here, +2), and the orders of the OAM mode signals are converted to 0, 1, and 2, respectively, by the phase control unit 16a.

[0029] As a result, the phases of the signals of orders 0, -1, -2 in the OAM mode of antenna element number 1 generated by signal generation unit 13a shown in Fig. 6 are shifted by +0 by phase control unit 16a and converted to phases of 0, 0, 0 in the OAM mode of orders 2, 1, 0 in the OAM mode of antenna element number 1, as shown in Fig. 8. Furthermore, the phases of the signals of orders 0, -π / 2, -π in the OAM mode of antenna element number 2 generated by signal generation unit 13a shown in Fig. 6 are shifted by +π by phase control unit 16a and converted to phases of π, π / 2, 0 in the OAM mode of orders 2, 1, 0 in the OAM mode of antenna element number 2, as shown in Fig. 8.

[0030] Furthermore, the phases of the signals of OAM mode orders 0, -1, and -2 of antenna element number 3 generated by signal generation unit 13a shown in Fig. 6 are shifted by +2π by phase control unit 16a as shown in Fig. 8, and converted to phases of 0, π, and 0 of signals of OAM mode orders 2, 1, and 0 of antenna element number 3. The phases of the signals of OAM mode orders 0, -1, and -2 of antenna element number 4 generated by signal generation unit 13a shown in Fig. 6 are shifted by +3π by phase control unit 16a as shown in Fig. 8, and converted to phases of π, 3π / 2, and 0 of signals of OAM mode orders 2, 1, and 0 of antenna element number 4. In other words, phase control unit 16a continuously shifts the phase of the OAM mode signal in the circumferential direction from 0 to nπ (3π in Fig. 8).

[0031] As a result, the spiral OAM mode signal D11 incident on the transmission plate 17a of the transmitter 10a is converted into a non-spiral OAM mode signal D12, which is then output from the transmission plate 17a. In FIG. 5, the phase of the signal output from the transmission antenna 15a is expressed as exp(jn １ φ), and the phase given by the phase control section 16a is expressed as exp(jn ２ φ), the phase of the signal emitted from the transmission plate 17a is expressed as exp(j(n １ +n ２ )φ).

[0032] As described above, in the transmitting device 10a according to the first embodiment, the transmitting antenna 15a, which is a circular array antenna, generates a multiplexed signal with OAM modes ranging from -n (here, n = 2) to 0. Then, the phase control unit 16a uses RIS (Reconfigurable Intelligent Surface) technology to perform phase control on the OAM signals transmitted through the transmitting plate 17a in a direction that increases all OAM modes by +n modes. The OAM modes generated by the phase control unit 16a range from 0 to +n. This makes it possible to reverse the OAM modes from the transmitting antenna 15a to the phase control unit 16a and the OAM modes from the phase control unit 16a to the receiving device 20, thereby suppressing differences in beam spread for each OAM mode.

[0033] Specifically, by giving the phase distribution of the OAM signal transmitted from the transmitting antenna 15a, which has 2n antenna elements and can generate n OAM modes, a phase distribution that continuously shifts the phase from 0 to nπ in the circumferential direction when passing through the transmitting plate 17a, the OAM mode (-n) with the highest absolute value is converted to mode 0, and OAM mode 0 is converted to OAM mode n.

[0034] As a result, even if a higher-order mode signal is included in an OAM (orbital angular momentum) mode signal, the phase control unit 16a and the transmission plate 17a can be used to prevent variations from occurring in the OAM signal transmitted from the transmitting device 10a to the receiving device 20, making it possible to perform long-distance transmission.

[0035] Second Embodiment Next, a communication system 100b according to a second embodiment of the present invention will be described. Note that the second embodiment has the same configuration as the first embodiment and parts that perform the same processing are denoted by the same reference numerals, and their description will be omitted.

[0036] 9 is a schematic configuration diagram of a communication system 100b according to a second embodiment of the present invention. The communication system 100b according to the second embodiment differs from the communication system 100a according to the first embodiment in that it includes a transmission device 10b instead of the transmission device 10a (FIG. 1).

[0037] The transmitting device 10b according to the second embodiment differs from the transmitting device 10a according to the first embodiment in that it includes a phase control unit 16b and a reflecting plate 17b instead of the transmitting antenna 15a, phase control unit 16a, and transmitting plate 17a (FIG. 1). Note that parts of the configuration of the communication system 100b according to the second embodiment shown in FIG. 9 that are similar to the configuration of the communication system 100a according to the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and description of those configurations will be omitted.

[0038] While the transmitting plate 17a in the first embodiment is a flat, transparent plate, the reflecting plate 17b in the second embodiment is shaped like a parabolic antenna, and the multiplexed signal transmitted from the signal transmitting unit 14a is reflected by the parabolic antenna-shaped reflecting plate 17b. The phase control unit 16b is connected to the transmitting device control unit 11a and the reflecting plate 17b. The phase control unit 16b includes a reconfigurable intelligent surface (RIS). The RIS used in the second embodiment is a planar surface composed of unit cells, and its characteristics are dynamically controlled to adjust the phase of the OAM mode signal reflected by the reflecting plate 17b. The reflecting plate 17b is a member shaped like a parabolic antenna. The RIS constituting the phase control unit 16b is attached to the inner surface of the reflecting plate 17b.

[0039] Fig. 10 is a flowchart showing the processing of a transmitting device 10b according to a second embodiment of the present invention. In the flowchart of Fig. 10 showing the processing of the transmitting device 10b according to the second embodiment, processing of steps S24 and S25 is performed instead of steps S14 and S15 in the flowchart of Fig. 4 showing the processing of the transmitting device 10a according to the first embodiment. Note that parts of the flowchart of Fig. 10 showing the processing of the transmitting device 10b according to the second embodiment that perform the same processing as in the flowchart of Fig. 4 showing the processing of the transmitting device 10a according to the first embodiment are assigned the same reference numerals, and description of those processes will be omitted.

[0040] In the flowchart shown in Figure 10, the phase control unit 16b determines whether the reflector 17b has received a multiplexed signal (step S24). If the reflector 17b determines that it has not received a multiplexed signal (NO in step S24), the phase control unit 16b performs the process of step S24 again after a predetermined time has elapsed. On the other hand, if the reflector 17b determines that it has received a multiplexed signal (YES in step S24), the phase control unit 16b performs phase control on the multiplexed signal received by the reflector 17b using RIS technology (step S25). Specifically, the phase control unit 16b converts the OAM mode so that the smallest order of the multiple OAM mode signals generated by the signal generation unit 13a is 0.

[0041] 11 is a diagram showing an overview of a transmission process by a transmitting device 10b according to a second embodiment of the present invention. In the second embodiment, the signal transmitting unit 14a transmits the multiplexed signal generated in step S12 via the transmitting antenna 15a toward the reflector 17b as a spiral OAM mode signal D21 as shown in FIG. 11. The spiral OAM mode signal D21 incident on the reflector 17b of the transmitting device 10b is converted into a non-spiral OAM mode signal D22 and emitted from the reflector 17b in the direction from which the signal D21 arrived.

[0042] In FIG. 11, the phase of the signal emitted from the transmitting antenna 15a is expressed as exp(jn １ φ), and the phase given by the phase control section 16b is expressed as exp(jn ２ φ), the phase of the signal emitted from the reflector 17b is expressed as exp(j(n １ +n ２ )φ).

[0043] In the transmitting device 10b according to the second embodiment, a multiplexed signal with OAM modes ranging from -n (here, n = 2) to 0 is generated from the transmitting antenna 15a, which is a circular array antenna. Then, the phase control unit 16a uses RIS (Reconfigurable Intelligent Surface) technology to perform phase control on the OAM signal reflected by the reflector 17b in a direction that increases all OAM modes by +n modes. The OAM modes generated by the phase control unit 16b range from 0 to +n. This makes it possible to reverse the OAM modes from the transmitting antenna 15a to the phase control unit 16b and the OAM modes from the phase control unit 16b to the receiving device 20, thereby suppressing differences in beam spread for each OAM mode.

[0044] As a result, even if a higher-order mode signal is included in an OAM (orbital angular momentum) mode signal, the phase control unit 16b and the reflector 17b can be used to prevent variations from occurring in the OAM signal transmitted from the transmitting device 10b to the receiving device 20, making it possible to perform long-distance transmission.

[0045] At least some of the functions of the transmitting devices 10a and 10b in the first and second embodiments described above, and at least some of the functions of the receiving device 20, may be implemented by a computer. In this case, a program for implementing these functions may be recorded on a computer-readable recording medium, and the program may be loaded and executed by a computer system. Note that the term "computer system" as used herein includes hardware such as an operating system (OS) and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, read-only memories (ROMs), 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 media that dynamically store programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or communication lines such as telephone lines, and media that store programs for a fixed period of time, such as volatile memory within the computer systems that serve as the server or client in such cases. Furthermore, the above program may be one that realizes part of the functions described above, or may be one that can realize the functions described above in combination with a program already recorded in a computer system, or may be one that is realized using a programmable logic device such as an FPGA.

[0046] 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.

[0047] The present invention can be applied to a transmitting device and a transmitting method that require long-distance transmission, in which it is necessary to prevent variations in the signal transmitted from the transmitting device to the receiving device even when a higher-order mode signal is included in the OAM (orbital angular momentum) mode signal.

[0048] DESCRIPTION OF SYMBOLS 10a, 10b... Transmitting device, 11a... Transmitting device control section, 12a... Transmitting device storage section, 13a... Signal generating section, 14a... Signal transmitting section, 15a... Transmitting antenna, 16a, 16b... Phase control section, 17a... Transmitting plate, 17b... Reflecting plate, 20... Receiving device, 21... Receiving device control section, 22... Receiving device storage section, 23... Receiving antenna, 24... Signal receiving section, 100a, 100b... Communication system

Claims

1. A transmitting device comprising: a signal generating unit that generates orbital angular momentum mode signals of -nth order (n is an integer of 1 or greater) to 0th order; a signal transmitting unit that transmits a multiplexed signal in which the orbital angular momentum mode signals of -nth order to 0th order generated by the signal generating unit are multiplexed; and a phase control unit that performs phase control to increase by a predetermined amount all orders of the orbital angular momentum mode signals multiplexed into the multiplexed signal transmitted by the signal transmitting unit.

2. The transmitting device according to claim 1, wherein the signal transmitting unit transmits the multiplexed signal using a circular array antenna or a multiple circular array antenna.

3. The transmitting device according to claim 1, wherein the phase control unit performs the phase control by increasing all orders of the -nth to 0th orbital angular momentum mode signals by +n to generate 0th to +nth orbital angular momentum mode signals.

4. The transmitting device according to claim 1, wherein the phase control section performs the phase control when the multiplexed signal transmitted from the signal transmitting section passes through a flat transmitting plate.

5. The transmitting device according to claim 1, wherein the phase control section performs the phase control when the multiplexed signal transmitted from the signal transmitting section is reflected by a parabolic antenna-shaped reflector.

6. A transmission method comprising: a signal generation process for generating orbital angular momentum mode signals of -nth order (n is an integer of 1 or greater) to 0th order; a signal transmission process for transmitting a multiplexed signal obtained by multiplexing the orbital angular momentum mode signals of -nth order to 0th order generated in the signal generation process; and a phase control process for performing phase control to increase by a predetermined amount all orders of the orbital angular momentum mode signals multiplexed into the multiplexed signal transmitted in the signal transmission process.

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