JP2017153018A - Radio communication system and communication method for radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication system capable of receiving radio waves of OAM with higher accuracy in relative to the prior arts without enlarging an opening diameter of an antenna, and a communication method for the radio communication system.SOLUTION: The present invention relates to a radio communication system comprising a transmitter station, a receiver station and a beam control element. The transmitter station includes: a modulation section for modulating an electromagnetic wave based on a signal including data to be transmitted; an a transmission antenna section including at least one set of circular array antennas each including multiple antenna elements for radiating the electromagnetic wave that is modulated by the modulation section. The beam control element includes a lens section which inputs the electromagnetic wave radiated from the transmission antenna section of the transmitter station, changes a radiation direction of the inputted electromagnetic wave and outputs the electromagnetic wave. The receiver station includes: a reception antenna section including at least one set of circular array antennas each including multiple antenna elements for receiving the electromagnetic wave outputted from the lens section; and a demodulation section for demodulating a reception signal of the electromagnetic wave received by the reception antenna section.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radio communication system and a communication method of the radio communication system.

  In wireless communication systems, techniques for increasing transmission capacity by multiplexing electromagnetic waves using orbital angular momentum (OAM: Orbital Angular Momentum) have been proposed (for example, Non-Patent Documents 1 and 2). That is, when the phase distributions of electromagnetic waves having different OAM modes are orthogonal to each other, the electromagnetic waves in each OAM mode can be separated by processing of the receiving station. Thereby, an electromagnetic wave can be multiplexed and transmitted using OAM.

O. Edfors and A. J. Johansson, “Is orbital angular momentum (OAM) based radio communication an unexploited area?”, IEEE transactions on antenna and propagation, Vol. 60, No. 2, pp.1126-1131, 2012 M. Tamagnone, JS Santiago, S. Capdevila, JR Mosig, J. Perruisseau-Carrier, “The orbital angular momentum (OAM) multiplexing controversy: OAM as a subset of MIMO”, IEEE 9th Conference on Antennas and Propagation, pp. 1 -5, 2015

  OAM electromagnetic waves propagate through space while maintaining a vortex phase distribution. In addition, the energy of the electromagnetic waves of OAM diffuses spatially.

  For this reason, in order to receive OAM electromagnetic waves with a predetermined reception power, it is necessary to increase the aperture diameter of the antenna according to the propagation distance, and the scale of the wireless communication system increases as the propagation distance increases. .

  An object of the present invention is to provide a radio communication system and a communication method of the radio communication system that can receive OAM electromagnetic waves with higher accuracy than before without increasing the aperture diameter of the antenna.

  A first invention is a wireless communication system including a transmission station, a reception station, and a beam control element, wherein the transmission station modulates an electromagnetic wave based on a signal including data to be transmitted, and a modulation unit And a transmitting antenna unit including at least one set of circular array antennas having a plurality of antenna elements that radiate electromagnetic waves modulated with a beam control element, which receives an electromagnetic wave radiated from the transmitting antenna unit of the transmitting station as an input. A receiving antenna unit that includes at least one set of circular array antennas having a plurality of antenna elements that receive electromagnetic waves output from the lens unit; And a demodulator that demodulates a received signal of the electromagnetic wave received by the receiving antenna unit.

  In the first invention, the lens unit forms an image of an electromagnetic wave radiated from the circular array antenna of the transmitting antenna unit at a size of the circular array antenna of the receiving antenna unit at a position where the receiving antenna unit is disposed. As described above, the antenna is disposed between the transmission antenna unit and the reception antenna unit.

  In the first invention, the transmitting antenna unit has a plurality of sets of circular array antennas arranged on a two-dimensional plane perpendicular to the optical axis direction of the lens unit, and the receiving antenna unit is an optical axis of the lens unit. A plurality of sets of circular array antennas arranged on a two-dimensional plane perpendicular to the direction, and a transmitting station generates a reference signal for radiating electromagnetic waves to each circular array antenna of the transmission antenna unit; A control unit that radiates the electromagnetic wave of the reference signal generated by the signal generation unit to each circular array antenna of the transmission antenna unit, and the receiving station transmits the reception state of the electromagnetic wave of the reference signal received by the reception antenna unit A measurement unit that measures each circular array antenna of the antenna unit and outputs the measurement result to the transmitting station is provided, and the control unit radiates an electromagnetic wave of a signal including data based on the measurement result Shaped array antenna is selected from a plurality of sets of circular array antenna of the transmitting antenna section.

  In the first invention, the transmission antenna unit has a plurality of sets of circular array antennas arranged concentrically on a two-dimensional plane perpendicular to the optical axis direction of the lens unit. A plurality of circular array antennas arranged concentrically on a two-dimensional plane perpendicular to the optical axis direction of the optical unit, and the lens unit radiates from each of the multiple circular array antennas of the transmission antenna unit. Between the transmitting antenna unit and the receiving antenna unit so that the image of the electromagnetic wave to be imaged is one of the sizes of a plurality of circular array antennas of the receiving antenna unit at the position where the receiving antenna unit is disposed. Placed in.

  In the first invention, the transmission station includes an OAM mode selection unit that selects an Orbital Angular Momentum (OAM) mode to be modulated in the modulation unit based on information added to a signal including data. The unit modulates the electromagnetic wave having the OAM selected by the OAM mode selection unit based on a signal including data, and the transmission antenna unit radiates the electromagnetic wave having the OAM modulated by the modulation unit.

  A second invention is a communication method of a wireless communication system comprising a transmitting station, a receiving station, and a beam control element, wherein the transmitting station modulates an electromagnetic wave based on a signal including data to be transmitted; The beam control element includes a first transmission step in which the transmission station radiates a modulated electromagnetic wave using a transmission antenna unit including at least one set of circular array antennas having a plurality of antenna elements, and a beam control element. An imaging step for changing the radiation direction of the input electromagnetic wave and outputting the electromagnetic wave radiated from the transmitting antenna unit using the lens unit, and a circular array antenna having a plurality of antenna elements A first receiving step for receiving an electromagnetic wave output from the lens unit using a receiving antenna unit including at least one set; and the receiving station receives the receiving antenna unit. The received signal of the electromagnetic wave and a demodulation step of demodulating.

  In the second invention, transmission is performed so that the image of the electromagnetic wave radiated from the circular array antenna of the transmission antenna unit is formed with the size of the circular array antenna of the reception antenna unit at the position where the reception antenna unit is disposed. It arrange | positions between an antenna part and a receiving antenna part.

  In the second invention, the transmitting station has a plurality of sets of circular array antennas arranged on a two-dimensional plane perpendicular to the optical axis direction of the lens unit. A second transmitting step for radiating electromagnetic waves, and a receiving station using a receiving antenna unit having a plurality of sets of circular array antennas arranged on a two-dimensional plane perpendicular to the optical axis direction of the lens unit. A second receiving step for receiving the electromagnetic wave of the reference signal radiated by each circular array antenna of the unit, and the receiving station for each circular array antenna of the transmitting antenna unit for the reception state of the electromagnetic wave of the reference signal received by the receiving antenna unit A measurement step of measuring and outputting the measurement result to the transmitting station, and the transmitting station emitting electromagnetic waves of a signal including data based on the measurement result received from the receiving station. A circular array antenna which includes a selection step of selecting from a plurality of sets of circular array antenna of the transmitting antenna section.

  In the second invention, the transmitting antenna unit has a plurality of sets of circular array antennas arranged concentrically on a two-dimensional plane perpendicular to the optical axis direction of the lens unit, and the receiving antenna unit includes a lens A plurality of circular array antennas arranged concentrically on a two-dimensional plane perpendicular to the optical axis direction of the optical unit, and the lens unit radiates from each of the multiple circular array antennas of the transmission antenna unit. Between the transmitting antenna unit and the receiving antenna unit so that the image of the electromagnetic wave to be imaged is one of the sizes of a plurality of circular array antennas of the receiving antenna unit at the position where the receiving antenna unit is disposed. Placed in.

  In the second invention, the transmitting station includes an OAM mode selection step for selecting an orbital angular momentum mode to be modulated based on information added to a signal including data, and the modulation step is selected in the OAM mode selection step. The electromagnetic wave having OAM is modulated based on a signal including data, and the first transmission step emits the electromagnetic wave having OAM modulated by the modulation unit step.

  The present invention makes it possible to receive OAM electromagnetic waves with higher accuracy than before by using the imaging effect of the lens without increasing the aperture diameter of the antenna.

1 is a diagram illustrating an embodiment of a wireless communication system. It is a figure which shows an example of the transmitting antenna shown in FIG. An example of arrangement | positioning of the transmitting antenna shown in FIG. 1, a receiving antenna, and a beam control element is shown. FIG. It is a figure which shows an example of energy distribution according to the radiation angle of the electromagnetic waves for every OAM mode radiated | emitted by the transmitting antenna shown in FIG. FIG. 6 illustrates another embodiment of a wireless communication system. It is a figure which shows an example of the transmitting antenna shown in FIG. It is a figure which shows an example of arrangement | positioning of the transmitting antenna, receiving antenna, and beam control element which were shown in FIG. It is a figure which shows an example of the communication process in the radio | wireless communications system shown in FIG.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 shows an embodiment of a wireless communication system.

  The wireless communication system SYS illustrated in FIG. 1 includes a transmitting station 10, a receiving station 20, and a beam control element 30. The transmitting station 10 and the receiving station 20 are connected to each other via radio.

  The transmission station 10 includes an IF (Interface) unit 11, an S / P (Serial-to-Parallel) unit 12, a modulation unit 13, and a transmission antenna ANT.

  The IF unit 11 is an input interface or the like, and receives a signal including data transmitted from a mobile communication terminal such as a smartphone or a tablet terminal, or a signal including data from a network. IF section 11 outputs the received signal (hereinafter also referred to as “transmission signal sequence”) to S / P section 12.

  The S / P unit 12 converts the transmission signal sequence from a serial signal to a parallel signal. The S / P unit 12 outputs the transmission signal sequence converted into the parallel signal to the modulation unit 13.

  The modulation unit 13 refers to the preamble added to the head of the transmission signal sequence received from the S / P unit 12, and acquires OAM information indicating an OAM mode for modulating electromagnetic waves. Based on the acquired OAM information, the modulation unit 13 modulates each stream of the transmission signal series converted into a parallel signal into OAM electromagnetic waves of different modes. Then, the modulation unit 13 multiplexes the OAM electromagnetic waves in each mode and outputs them to the transmission antenna ANT.

  Note that a processor or the like included in the transmission station 10 may function as an OAM mode selection unit that selects an OAM mode with reference to a preamble added to the head of a transmission signal sequence, for example. In this case, the processor or the like outputs OAM information indicating the selected OAM mode to the modulation unit 13.

  The transmission antenna ANT is a circular array antenna in which a plurality of antenna elements EA are arranged on the circumference, and has at least one set of circular array antennas. The transmission antenna ANT radiates the OAM electromagnetic wave received from the modulation unit 13 toward the reception station 20. The transmission antenna ANT will be described with reference to FIG.

  The receiving station 20 has a receiving antenna ANR and a demodulator 21.

  Similar to the transmission antenna ANT, the reception antenna ANR is a circular array antenna in which a plurality of antenna elements EA are arranged on the circumference, and has at least one set of circular array antennas. The receiving antenna ANR receives an electromagnetic wave having OAM radiated from the transmitting station 10 via the beam control element 30, and outputs a received signal of the received OAM electromagnetic wave to the demodulator 21. The receiving antenna ANR will be described with reference to FIG.

  The demodulator 21 performs demodulation processing on the received signal of the OAM electromagnetic wave. Then, the receiving station 20 outputs the transmission signal sequence to an external mobile communication terminal or network that is the transmission destination indicated by the preamble of the demodulated transmission signal sequence via the output interface included in the receiving station 20. To do.

  The beam control element 30 includes, for example, a lens 31 that is a convex lens. The beam control element 30 uses the lens 31 to input an electromagnetic wave transmitted from the transmission antenna ANT of the transmission station 10, changes the radiation direction of the input electromagnetic wave, and outputs it. The lens 31 is a single convex lens, but may be a combination of a plurality of lenses. The lens 31 may be an element having the same function as the convex lens instead of the convex lens.

  The beam control element 30 may be included in the transmitting station 10 or the receiving station 20.

  Further, the arrangement of the transmitting station 10, the receiving station 20, and the beam control element 30 will be described with reference to FIG.

  FIG. 2 shows an example of the transmission antenna ANT shown in FIG. As shown in FIG. 2, the transmission antenna ANT has N sets of circular array antennas SA (SA (1) -SA (N)). Each of the circular array antennas SA of the transmission antenna ANT has a different radius R1 (R11-R1N) and is arranged concentrically. For example, eight antenna elements EA are arranged at intervals of 2π / 8 on the circumference of each circular array antenna SA. When the number of antenna elements EA included in each circular array antenna SA is M, the antenna elements EA are arranged at an interval of an angle 2π / M.

  The number N of circular array antennas SA in the transmission antenna ANT and the number of antenna elements EA included in each circular array antenna SA are appropriately determined according to the scale of the wireless communication system SYS and the required communication quality. It is preferable.

  Next, a method for modulating an electromagnetic wave having an OAM mode using the transmission antenna ANT will be described. For example, the circular array antenna SA (n) (n is an integer from 1 to N) shown in FIG. 2 radiates an electromagnetic wave having a single OAM mode j (j is an integer from 0 to M−1). In this case, an electromagnetic wave having a signal waveform whose phase is different by 2πj / M for each antenna element EA is radiated. Thereby, the circular array antenna SA (n) radiates an electromagnetic wave of OAM mode j.

  Further, when the circular array antenna SA (n) radiates two or more OAM mode electromagnetic waves, the circular array antenna SA (n) radiates an electromagnetic wave obtained by combining the signal waveforms of the OAM modes from the antenna element. For example, when the OAM mode is j1 and j2, the circular array antenna SA (n) has a signal waveform whose phase differs by 2πj1 / M for each antenna element EA and a signal waveform whose phase differs by 2πj2 / M for each antenna element EA. The electromagnetic wave of the signal waveform which synthesize | combined is radiated. Thereby, circular array antenna SA (n) can radiate | emit the electromagnetic waves of OAM mode j1 and j2 simultaneously. J1 and j2 are integers from 0 to M-1.

  On the other hand, the receiving antenna ANR has L sets of circular array antennas arranged in concentric circles having different radii R2 (R21-R2L), similarly to the transmitting antenna ANT shown in FIG. Similarly to the transmission antenna ANT, eight antenna elements EA are arranged at intervals of 2π / 8 on the circumference of each of the circular array antennas of the reception antenna ANR. Note that the number L of sets of circular array antennas of the reception antenna ANR may be the same as or different from the number N of sets of circular array antennas of the transmission antenna ANT. Further, the number of antenna elements EA included in each circular array antenna of the reception antenna ANR may be the same as or different from the number of antenna elements EA included in each circular array antenna SA of the transmission antenna ANT.

  The reception antenna ANR transmits an OAM electromagnetic wave radiated by the circular array antenna SA (n) (n is an integer from 1 to N) of the transmission antenna ANT via the beam control element 30 to any one of the reception antennas ANR. Receive with a set of circular array antennas. The receiving antenna ANR outputs a received signal of the received electromagnetic wave to the demodulator 21.

  When the OAM electromagnetic wave is in a single OAM mode, the demodulator 21 performs phase shift processing so that the phases of the received signals are aligned between the antenna elements EA of the circular array antenna of the receiving antenna ANR that has received the OAM electromagnetic wave. Execute. The demodulator 21 adds the signal waveforms of the received signals of the antenna elements EA whose phases are aligned with each other to restore the modulated signal. Then, the demodulator 21 demodulates the restored modulated signal.

  On the other hand, when the OAM electromagnetic wave has a plurality of OAM modes, the demodulator 21 receives the IDFT () on the received signal received at the same time in each antenna element EA of the circular array antenna of the receiving antenna ANR that has received the OAM electromagnetic wave. Inverse discrete Fourier transform) processing is performed to separate the received signals for each OAM mode. Then, the demodulator 21 demodulates the separated received signals in each OAM mode.

  FIG. 3 shows an example of the arrangement of the transmission antenna ANT, the reception antenna ANR, and the beam control element 30 shown in FIG. In FIG. 3, a set of circular array antennas having a radius R11 (ie, the circular array antenna SA (1) shown in FIG. 2) is shown as the transmitting antenna ANT, and a set of circular arrays having a radius R21 is shown as the receiving antenna ANR. Indicates an antenna. In FIG. 3, a lens 31 having a diameter dL and a focal length f is shown as the beam control element 30. The diameter dL of the lens 31 is preferably set according to the beam width of the electromagnetic wave radiated from the transmitting antenna ANT.

  In FIG. 3, the direction of the optical axis of the lens 31 is the X axis, and the directions perpendicular to the optical axis of the lens 31 are the Y axis and the Z axis. In FIG. 3, the transmission antenna ANT is arranged on the YZ plane so that the origin of the XYZ coordinates coincides with the center of the circular array antenna SA (1) of the transmission antenna ANT. Further, the reception antenna ANR is arranged on the YZ plane at a distance x so as to face the transmission antenna ANT so that the X axis passes through the center of the circular array antenna included in the reception antenna ANR. That is, the center of the transmission antenna ANT, the center of the reception antenna ANR, and the optical axis of the lens 31 are arranged on the X axis.

  When the electromagnetic wave radiated from the transmitting antenna ANT is imaged at the position of the distance x where the receiving antenna ANR is arranged by the lens 31 having the focal length f arranged at a position a distance a from the transmitting antenna ANT, the expression ( The condition 1) is satisfied.

1 / a + 1 / (xa) = 1 / f (1)
The magnification k of the image of the transmission antenna ANT formed at the position of the reception antenna ANR is calculated using Expression (2).

k = (x−a) / a (2)
When the size of the image of the transmitting antenna ANT having the radius R11 is the size of the receiving antenna ANR having the radius R21, the magnification k is R21 / R11. As a result, the distance a at which the lens 31 is disposed is expressed by Expression (3) using Expression (2) and the radii R11 and R21 of the transmission antenna ANT and the reception antenna ANR.

a = x × R11 / (R11 + R21) (3)
Further, the focal length f of the lens 31 is related to the radius R11 of the transmission antenna ANT and the radius R21 of the reception antenna ANR as shown in the equation (4) based on the equations (1) and (3).

f = x * R11 / (R11 + R21) * (1-R11 / (R11 + R21)) (4)
That is, each of the transmission antenna ANT, the reception antenna ANR, and the beam control element 30 is arranged on the X axis so as to satisfy the conditions of the expressions (3) and (4).

  FIG. 3 shows the case where the transmitting antenna ANT uses a circular array antenna having a radius R11 and the receiving antenna ANR uses a circular array antenna having a radius R21. However, each of the transmitting antenna ANT and the receiving antenna ANR has a different radius. Also in the case of using the circular array antenna, the distance “a” and the focal length “f” of the lens 31 are calculated using the expressions (1) and (2).

  Note that a circular array antenna SA (i) satisfying the conditions of the equations (3) and (4) and having a radius R1i of the transmitting antenna ANT and a circular array antenna having a radius R2m of the receiving antenna ANR are R2m = k × When the condition of R1i is satisfied, communication between the circular array antenna SA (1) having the radius R11 of the transmitting antenna ANT and the circular array antenna having the radius R21 of the receiving antenna ANR, and the circular array antenna SA having the radius R1i of the transmitting antenna ANT. Communication between (i) and the circular array antenna having the radius R2m of the receiving antenna ANR may be performed simultaneously. Here, i is an integer from 2 to N, and m is an integer from 2 to L.

  In this case, the electromagnetic wave radiated from the circular array antenna SA (1) of the transmitting antenna ANT is received by the circular array antenna having the radius R21 of the receiving antenna ANR and input to the demodulator 21. On the other hand, the electromagnetic wave radiated from the circular array antenna SA (i) of the transmitting antenna ANT is received by the circular array antenna having the radius R2m of the receiving antenna ANR and input to the demodulator 21. The demodulator 21 demodulates the received signal input from the circular array antenna having the radius R21 of the receiving antenna ANR and the received signal input from the circular array antenna having the radius R2m independently.

  FIG. 4 shows an example of energy distribution according to the radiation angle of the electromagnetic wave for each OAM mode radiated by the transmission antenna ANT shown in FIG. The horizontal axis of FIG. 4 indicates the radiation angle θ of the electromagnetic wave of OAM radiated from the transmission antenna ANT with reference to the direction of the X axis (the optical axis of the lens 31). The vertical axis in FIG. 4 shows the energy ratio between the total radiant energy of the electromagnetic wave radiated by the transmitting antenna ANT and the cumulative value of the radiant energy of the electromagnetic wave radiated at a radiation angle from 0 degree to θ degree.

  In obtaining the distribution shown in FIG. 4, the number of antenna elements EA of the circular array antenna having the radius R11 of the transmitting antenna ANT and the circular array antenna having the radius R21 of the receiving antenna ANR is set to twelve. The frequency of the OAM electromagnetic wave is 60 gigahertz, the radius R11 is 0.5 centimeter (that is, one wavelength of the electromagnetic wave), and the radius R21 is 10 centimeters. The distance x between the transmitting antenna ANT and the receiving antenna ANR is 10 meters, and the transmitting station 10, the receiving station 20, and the beam control element 30 are 0.125 centimeters (0.25 wavelength) from the ground. Is going to be placed.

  As shown in FIG. 4, for example, when the OAM mode is “1”, the radiation angle θ at which the energy ratio is 80% indicates 27 degrees. When the radiation angle θ is 27 degrees and the beam control element 30 is not disposed, the beam width of the OAM mode “1” electromagnetic wave at the position of 10 meters where the receiving antenna ANR is disposed is 5.09 meters. However, when the lens 31 having a focal length f of 45.35 centimeters is disposed at a position 47.62 centimeters (distance a) from the transmitting antenna ANT, the OAM mode “1” at the position where the receiving antenna ANR is disposed. The beam width of the electromagnetic wave is 10 centimeters (that is, the radius R21 of the receiving antenna ANR). That is, by arranging the beam control element 30, the spread of the electromagnetic wave in the OAM mode “1” can be reduced by 0.020 times. Further, the spread of electromagnetic waves when the OAM mode is “0”, “2”, or “3” can be reduced as in the case of the OAM mode “1”. Thereby, the scale of the wireless communication system SYS can be suppressed.

  The diameter dL of the lens 31 when the OAM mode is “1” is preferably larger than 2 × 47.62 centimeters (distance a) × tan (27 degrees) (that is, 48.53 centimeters).

  As described above, in the embodiment shown in FIGS. 1 to 4, the beam control element 30 is arranged so that the size of the image of the transmission antenna ANT becomes the size of the reception antenna ANR at the position where the reception antenna ANR is arranged. . That is, the beam width of the OAM electromagnetic wave radiated from the transmitting antenna ANT can be set to the size of the receiving antenna ANR by the imaging action of the lens 31 included in the beam control element 30. As a result, the radio communication system SYS can receive the OAM electromagnetic waves with higher accuracy than the conventional one without increasing the aperture diameter of the reception antenna ANR, and can suppress the scale of the radio communication system SYS.

  FIG. 5 shows another embodiment of a wireless communication system. Elements having the same or similar functions as those described in FIG. 1 are denoted by the same or similar reference numerals, and detailed description thereof will be omitted.

  The wireless communication system SYS1 illustrated in FIG. 5 includes a transmitting station 10A, a receiving station 20A, and a beam control element 30.

  The transmission station 10A includes an IF unit 11, an S / P unit 12, a modulation unit 13, a control unit 14, a reference signal generation unit 15, and a transmission antenna ANTa.

  The control unit 14 is realized by, for example, a processor included in the transmission station 10A executing a control program stored in a storage device such as a hard disk device included in the transmission station 10A, and controls the operation of the transmission station 10A. To do. For example, the control unit 14 displays the measurement results such as SNR (Signal-to-Noise Ratio) and BER (Bit Error Rate) of the electromagnetic wave received by the receiving antenna ANRa measured by the receiving station 20A as the IF unit 11 or the IF unit. 11 is received via an input interface included in the transmitting station 10A different from 11. Based on the received measurement results, the control unit 14 selects a set of circular array antennas that radiate OAM electromagnetic waves from a plurality of sets of circular array antennas included in the transmission antenna ANTa. In addition, the control unit 14 causes the reference signal generation unit 15 to generate a reference signal that causes the reception station 20A to measure the SNR, BER, and the like of the electromagnetic wave radiated from the transmission antenna ANTa. The control unit 14 sequentially transmits the OAM electromagnetic waves modulated based on the generated reference signal to each of a plurality of circular array antennas of the transmission antenna ANTa.

  Note that a processor or the like included in the transmission station 10A may function as an OAM mode selection unit that selects an OAM mode with reference to a preamble added to the head of a transmission signal sequence, for example. In this case, the processor or the like outputs OAM information indicating the selected OAM mode to the modulation unit 13.

  Based on the control instruction from the control unit 14, the reference signal generation unit 15 generates a reference signal for causing the receiving station 20A to measure the SNR, BER, and the like of the electromagnetic wave radiated from each circular array antenna of the transmission antenna ANTa. The generated reference signal is output to the transmission antenna ANTa.

  The transmission antenna ANTa is a circular array antenna in which a plurality of antenna elements EA are arranged on the circumference, and has a plurality of sets of circular array antennas. The transmission antenna ANTa is used by the modulation unit 13 based on a transmission signal sequence received via the IF unit 11 using a set of circular array antennas selected by the control unit 14 among a plurality of sets of circular array antennas. A modulated OAM electromagnetic wave is emitted. Further, the transmission antenna ANTa radiates the electromagnetic wave of the reference signal generated by the reference signal generation unit 15 to each of a plurality of sets of circular array antennas based on the control instruction of the control unit 14. The transmission antenna ANTa will be described with reference to FIG.

  The receiving station 20A includes a receiving antenna ANRa, a demodulator 21 and a measuring unit 22.

  Similar to the transmission antenna ANTa, the reception antenna ANRa is a circular array antenna in which a plurality of antenna elements EA are arranged on the circumference, and has at least one set of circular array antennas. The receiving antenna ANRa receives the electromagnetic wave having the OAM radiated from the transmitting station 10 </ b> A via the beam control element 30, and outputs the received signal of the received OAM electromagnetic wave to the demodulator 21. The reception antenna ANRa outputs the received signal of the received electromagnetic wave to the measurement unit 22 when the electromagnetic wave radiated from the transmission station 10A is a reference signal. The receiving antenna ANRa will be described with reference to FIG.

  Note that it is preferable that the receiving station 20A outputs the received signal to the demodulating unit 21 and the measuring unit 22 after compensating for the phase distortion generated in the received signal due to the imaging action using a variable phase shifter or the like.

  The measurement unit 22 measures the SNR, BER, and the like of the reception signal of the electromagnetic wave of the reference signal that is radiated from each circular array antenna of the transmission antenna ANTa of the transmission station 10A and received by the reception antenna ANRa. The measurement unit 22 feeds back a measurement result to the transmission station 10A in a wired or wireless manner via an output interface included in the reception station 20A. Note that SNR, BER, and the like are examples of reception states.

  FIG. 6 shows an example of the transmission antenna ANTa shown in FIG. FIG. 6 shows, for example, six sets of circular array antennas SAa having a radius R11 or a radius R12 among the N sets of circular array antennas SAa (SAa (1) -SAa (N)) included in the transmission antenna ANTa. Each of the circular array antennas SAa of the transmission antennas ANTa is arranged on the YZ plane perpendicular to the optical axis (X axis) of the lens 31 so that the centers of the circular array antennas SAa do not overlap. For example, the circular array antenna SAa (2) is disposed at a position of a distance h from the center of the circular array antenna SAa (1) and an angle φ with respect to the Y axis. Then, on the circumference of each circular array antenna SAa, eight antenna elements EA are arranged at intervals of 2π / 8 as in the circular array antenna SA shown in FIG.

  The radii of the circular array antennas SAa may all be the same or all different. Further, the number N of circular array antenna sets in the transmission antenna ANTa and the number of antenna elements EA of each circular array antenna are appropriately determined according to the scale of the wireless communication system SYS1 and the required communication quality. preferable.

  On the other hand, the reception antenna ANRa has a plurality of sets of circular array antennas, similar to the transmission antenna ANTa shown in FIG. 6, and each circular array antenna has a distance x so that the centers of the circular array antennas do not overlap each other. It is arranged on the YZ plane at the position. In each of the circular array antennas of the reception antenna ANRa, eight antenna elements EA are arranged on the circumference at intervals of 2π / 8 as in the case of the transmission antenna ANTa. Note that the number of sets of circular array antennas of the reception antenna ANRa may be the same as or different from the number of sets of circular array antennas of the transmission antenna ANTa. Further, the number of antenna elements EA included in each circular array antenna of the reception antenna ANRa may be the same as or different from the number of antenna elements EA included in each circular array antenna of the transmission antenna ANTa. Further, the radii of the circular array antennas of the receiving antenna ANRa may all be the same or all different.

  FIG. 7 shows an example of the arrangement of the transmission antenna ANTa, the reception antenna ANRa, and the beam control element 30 shown in FIG. The same or similar elements as those described in FIG. 3 are denoted by the same or similar reference numerals, and detailed description thereof will be omitted.

  In FIG. 7, two sets of circular array antennas SAa (1) and SAa (2) having a radius R11 are shown as the transmitting antenna ANTa, and one set of circular array antennas having a radius R21 are shown as the receiving antenna ANRa.

  In FIG. 7, the circular array antenna SAa (1) of the transmission antenna ANTa is arranged on the YZ plane so that the origin of the XYZ coordinates coincides with the center of the circular array antenna SAa (1). Further, as shown in FIG. 6, the circular array antenna SAa (2) is arranged on the YZ plane so that the center of the circular array antenna SAa (2) comes to the position of the distance h and the angle φ. On the other hand, the receiving antenna ANRa faces the circular array antenna SAa (1) of the transmitting antenna ANTa so that the X axis passes through the center of the circular array antenna of the receiving antenna ANRa, similarly to the receiving antenna ANR shown in FIG. Arranged on the YZ plane. That is, the center of the circular array antenna SA (1) of the transmission antenna ANTa, the center of the reception antenna ANRa, and the optical axis of the lens 31 are arranged on the X axis. Further, the transmission antenna ANTa, the reception antenna ANRa, and the lens 31 are arranged so as to satisfy the conditions of the expressions (3) and (4).

  In this case, the OAM electromagnetic wave radiated by the circular array antenna SAa (1) of the transmission antenna ANTa shown in FIG. 7 is located at the position where the reception antenna ANRa is arranged, similarly to the transmission antenna ANT shown in FIG. An image is formed by the lens 31 with a radius R21. On the other hand, since the circular array antenna SAa (2) shown in FIG. 7 is arranged at a position offset by a distance h and an angle φ with respect to the optical axis (X axis) of the lens 31, the circular array antenna SAa (2 The OAM electromagnetic wave radiated by (1) forms an image 40 at a position different from the position of the antenna ANTa. For this reason, it becomes difficult for the OAM electromagnetic wave radiated from the circular array antenna SAa (2) to be received by the receiving antenna ANRa with a predetermined reception power.

  When the offset of the image 40 with respect to the position of the antenna ANTa is a distance h ′ and an angle φ ′, the image 40 and the circular array antenna SAa (2) of the transmission antenna ANTa have a distance h ′ = (x−a) × h / a and the angle φ ′ = π + φ.

  For example, when the position of the receiving station 20A is shifted due to a disaster such as an earthquake or an artificial action, and the position of the receiving antenna ANRa becomes the position of the image 40, the receiving antenna ANRa is a circular array antenna SAa of the transmitting antenna ANTa. It becomes difficult to receive the OAM electromagnetic wave radiated by (1) with a predetermined reception power. On the other hand, the receiving antenna ANRa can receive OAM electromagnetic waves radiated from the circular array antenna SAa (2) of the transmitting antenna ANTa with a predetermined reception power. That is, as shown in FIG. 6, the transmission antenna ANTa is arranged such that each of the N sets of circular array antennas SAa is distributed on the YZ plane, so that the reception antenna ANRa of the reception station 20A can be any of the transmission antennas ANTa. The OAM electromagnetic wave radiated by the pair of circular array antennas SAa can be received.

  Therefore, the control unit 14 generates a reference signal in the reference signal generation unit 15 in order to select a set of circular array antennas SAa that radiate OAM electromagnetic waves among the N sets of circular array antennas SAa of the transmission antennas ANTa. Let The control unit 14 sequentially transmits the OAM electromagnetic waves modulated based on the reference signal generated by the reference signal generation unit 15 to each of the N circular array antennas SAa of the transmission antenna ANTa. The control unit 14 receives, from the receiving station 20A, the measurement results obtained by the measurement unit 22 such as SNR and BER of the electromagnetic waves radiated from each circular array antenna SAa of the transmission antenna ANTa. For example, the control unit 14 refers to the received measurement result and selects the circular array antenna SAa in which the highest SNR (or lowest BER) is measured.

  FIG. 8 shows an example of communication processing in the wireless communication system SYS1 shown in FIG. For example, the processing from step S100 to step S170 is executed by the transmitting station 10A. Further, the processing from step S200 to step S240 is executed by the receiving station 20A. That is, FIG. 8 shows an embodiment of a communication method of a wireless communication system.

  8 is started when the transmitting station 10A receives a transmission signal sequence.

  In step S100, the control unit 14 causes the reference signal generation unit 15 to generate a reference signal.

  In step S110, the control unit 14 sequentially transmits the OAM electromagnetic waves modulated based on the reference signal generated in step S100 to each of the circular array antennas SAa (1) to SAa (N) of the transmission antenna ANTa. Therefore, the variable i is initialized to 1.

  In step S120, the control unit 14 causes the circular array antenna SAa (i) to emit the OAM electromagnetic wave modulated based on the reference signal generated in step S100.

  In step S130, the control unit 14 receives measurement results such as SNR and BER for the electromagnetic wave radiated in step S120 from the receiving station 20A. Then, the control unit 14 stores the received measurement result in the storage device of the transmitting station 10A in association with the circular array antenna SAa (i).

  In step S140, the control unit 14 increases the variable i by one.

  In step S150, the control unit 14 determines whether or not the variable i is smaller than the number N of pairs of circular array antennas SAa. If the variable i is smaller than the number N of sets, the processing of the transmitting station 10A proceeds to step S120. On the other hand, when the variable i is equal to or greater than the number N of sets, the processing of the transmitting station 10A proceeds to step S160.

  In step S160, the control unit 14 selects the circular array antenna SAa that radiates the OAM electromagnetic wave of the transmission signal series based on the measurement result of each circular array antenna SAa received in step S130. For example, the control unit 14 selects the circular array antenna SAa in which the highest SNR is measured. Alternatively, the control unit 14 selects the circular array antenna SAa in which the lowest BER is measured.

  In step S170, the control unit 14 causes the circular array antenna SAa of the transmission antenna ANTa selected in step S160 to emit an electromagnetic wave having an OAM modulated by the modulation unit 13 based on the transmission signal sequence. Then, the transmitting station 10A ends the communication process.

  Each time the transmitting station 10A receives a transmission signal sequence, the transmitting station 10A executes the processing from step S100 to step S170. For example, when the measurement unit 22 measures the SNR or the like of the received signal of the transmission signal sequence, the transmission station 10A refers to the measured SNR or the like and determines that the predetermined communication quality is maintained. The processing from step S100 to step S150 may be omitted.

  On the other hand, in step S200, the receiving antenna ANRa receives the OAM electromagnetic wave radiated in step S120 and modulated based on the reference signal. Then, the receiving antenna ANRa outputs a received signal of the received electromagnetic wave to the measuring unit 22.

  In step S210, the measurement unit 22 measures the SNR, BER, and the like of the reception signal of the electromagnetic wave received in step S200.

  In step S220, the measurement unit 22 transmits the measurement result measured in step S210 to the transmitting station 10A.

  In step S230, the receiving antenna ANRa receives the OAM electromagnetic wave modulated based on the transmission signal sequence radiated in step S170. Then, the receiving antenna ANRa outputs a received signal of the received electromagnetic wave to the demodulator 21.

  In step S240, the demodulator 21 performs demodulation processing on the received electromagnetic wave signal received in step S230. Then, the demodulation unit 21 outputs the transmission signal sequence to an external mobile communication terminal or network that is the transmission destination indicated by the preamble of the demodulated transmission signal sequence via an output interface included in the receiving station 20. . Then, the receiving station 20A ends the communication process.

  The receiving station 20A executes the processing from step S200 to step S240 every time the transmitting station 10A receives the transmission signal sequence.

  As described above, in the embodiment shown in FIGS. 5 to 8, the beam control element 30 is arranged so that the size of the image of the transmission antenna ANTa becomes the size of the reception antenna ANRa at the position where the reception antenna ANRa is arranged. . In other words, the beam width of the OAM electromagnetic wave radiated from the transmitting antenna ANTa can be made the size of the receiving antenna ANRa by the imaging action of the lens 31 included in the beam control element 30. As a result, the radio communication system SYS1 can receive the OAM electromagnetic wave with higher accuracy than the conventional one without increasing the aperture diameter of the reception antenna ANRa, and can suppress the scale of the communication system SYS1.

  Further, each of the N sets of circular array antennas SAa of the transmission antennas ANTa are arranged on a two-dimensional plane perpendicular to the optical axis of the lens 31 so that the centers of the circular array antennas SAa do not overlap. Then, when transmitting the transmission signal sequence, the control unit 14 uses the reference signal by the reference signal generation unit 15 to use the circular array antenna having the highest SNR (or the lowest BER) of the electromagnetic wave received by the receiving station 20A. Select SAa. Thereby, even when the position of the receiving station 20A is shifted due to a disaster or the like, the radio communication system SYS1 can transmit a transmission signal sequence.

  From the above detailed description, features and advantages of the embodiments will become apparent. This is intended to cover the features and advantages of the embodiments described above without departing from the spirit and scope of the claims. Also, any improvement and modification should be readily conceivable by those having ordinary knowledge in the art. Therefore, there is no intention to limit the scope of the inventive embodiments to those described above, and appropriate modifications and equivalents included in the scope disclosed in the embodiments can be used.

DESCRIPTION OF SYMBOLS 10,10A ... Transmission station; 11 ... IF part; 12 ... S / P part; 13 ... Modulation part; 14 ... Control part; 15 ... Reference signal generation part; 20, 20A ... Reception station; Measurement unit; 30 ... Beam control element; 31 ... Lens; 40 ... Image; ANT, ANTa ... Transmission antenna; ANR, ANRa ... Reception antenna; EA ... Antenna element; SA (1) -SA (N), SAa (1) -SAa (N) ... circular array antenna; SYS, SYS1 ... wireless communication system

Claims (10)

A wireless communication system comprising a transmitting station, a receiving station, and a beam control element,
The transmitting station is
A modulation unit that modulates electromagnetic waves based on a signal including data to be transmitted;
A transmission antenna unit including at least one circular array antenna having a plurality of antenna elements that radiate electromagnetic waves modulated by the modulation unit;
The beam control element is
With the input of the electromagnetic wave radiated from the transmission antenna unit of the transmission station, comprising a lens unit that changes the radiation direction of the input electromagnetic wave and outputs,
The receiving station is
A receiving antenna unit including at least one set of circular array antennas having a plurality of antenna elements for receiving electromagnetic waves output from the lens unit;
A wireless communication system, comprising: a demodulation unit that demodulates a reception signal of an electromagnetic wave received by the reception antenna unit. The wireless communication system according to claim 1, wherein
The lens unit forms an image of an electromagnetic wave radiated from the circular array antenna of the transmitting antenna unit with a size of the circular array antenna of the receiving antenna unit at a position where the receiving antenna unit is disposed. As described above, the wireless communication system is arranged between the transmitting antenna unit and the receiving antenna unit. The wireless communication system according to claim 1 or 2,
The transmission antenna unit includes a plurality of sets of the circular array antennas arranged on a two-dimensional plane perpendicular to the optical axis direction of the lens unit,
The receiving antenna unit includes a plurality of sets of the circular array antennas arranged on a two-dimensional plane perpendicular to the optical axis direction of the lens unit,
The transmitting station is
A signal generation unit that generates a reference signal for radiating electromagnetic waves to each of the circular array antennas of the transmission antenna unit;
A control unit that radiates electromagnetic waves of the reference signal generated by the signal generation unit to each of the circular array antennas of the transmission antenna unit,
The receiving station is
Measuring the reception state of the electromagnetic wave of the reference signal received by the reception antenna unit for each of the circular array antennas of the transmission antenna unit, comprising a measurement unit for outputting the measurement result to the transmission station;
The control unit selects a circular array antenna that radiates an electromagnetic wave of a signal including the data from the plurality of sets of circular array antennas of the transmission antenna unit based on the measurement result. apparatus The wireless communication system according to claim 1, wherein
The transmission antenna unit includes a plurality of sets of the circular array antennas arranged concentrically on a two-dimensional plane perpendicular to the optical axis direction of the lens unit,
The receiving antenna unit includes a plurality of sets of the circular array antennas arranged concentrically on a two-dimensional plane perpendicular to the optical axis direction of the lens unit,
The lens unit includes the plurality of sets of circular arrays of the reception antenna unit at a position where the image of the electromagnetic wave radiated from each of the plurality of sets of circular array antennas of the transmission antenna unit is disposed. A radio communication system, wherein the radio communication system is arranged between the transmitting antenna unit and the receiving antenna unit so as to form an image with any size of the antenna. The wireless communication system according to any one of claims 1 to 4,
The transmitting station includes an OAM mode selection unit that selects an Orbital Angular Momentum (OAM) mode to be modulated in the modulation unit based on information added to a signal including the data,
The modulation unit modulates an electromagnetic wave having the OAM selected by the OAM mode selection unit based on a signal including the data,
The radio communication system, wherein the transmitting antenna unit radiates an electromagnetic wave having an OAM modulated by the modulating unit. A communication method of a wireless communication system comprising a transmitting station, a receiving station, and a beam control element,
A modulation step in which the transmitting station modulates an electromagnetic wave based on a signal including data to be transmitted;
A first transmitting step in which the transmitting station radiates the modulated electromagnetic wave using a transmitting antenna unit including at least one set of circular array antennas having a plurality of antenna elements;
An imaging step in which the beam control element uses the lens unit included in the beam control element to input the electromagnetic wave radiated from the transmission antenna unit, changes the radiation direction of the input electromagnetic wave, and outputs it,
A first receiving step in which the receiving station receives an electromagnetic wave output from the lens unit using a receiving antenna unit including at least one set of circular array antennas having a plurality of antenna elements;
And a demodulation step of demodulating a reception signal of an electromagnetic wave received by the reception antenna unit. In the communication method of the radio | wireless communications system of Claim 6,
The lens unit forms an image of an electromagnetic wave radiated from the circular array antenna of the transmitting antenna unit with a size of the circular array antenna of the receiving antenna unit at a position where the receiving antenna unit is disposed. As described above, the communication method of the wireless communication system, wherein the communication method is arranged between the transmission antenna unit and the reception antenna unit. In the communication method of the radio | wireless communications system of Claim 6 or Claim 7,
The transmitting station has a plurality of sets of the circular array antennas arranged on a two-dimensional plane perpendicular to the optical axis direction of the lens unit. A second transmission step of radiating
The receiving station includes the receiving antenna unit having a plurality of sets of the circular array antennas arranged on a two-dimensional plane perpendicular to the optical axis direction of the lens unit. A second receiving step of receiving an electromagnetic wave of the reference signal radiated by the array antenna;
The receiving station measures the reception state of the electromagnetic wave of the reference signal received by the receiving antenna unit for each of the circular array antennas of the transmitting antenna unit, and a measurement step of outputting the measurement result to the transmitting station;
A selection in which the transmitting station selects, from the plurality of sets of circular array antennas of the transmitting antenna unit, a circular array antenna that radiates an electromagnetic wave of a signal including the data based on the measurement result received from the receiving station. A communication method for a wireless communication system. In the communication method of the radio | wireless communications system of Claim 6,
The transmission antenna unit includes a plurality of sets of the circular array antennas arranged concentrically on a two-dimensional plane perpendicular to the optical axis direction of the lens unit,
The receiving antenna unit includes a plurality of sets of the circular array antennas arranged concentrically on a two-dimensional plane perpendicular to the optical axis direction of the lens unit,
The lens unit includes the plurality of sets of circular arrays of the reception antenna unit at a position where the image of the electromagnetic wave radiated from each of the plurality of sets of circular array antennas of the transmission antenna unit is disposed. A communication method of a radio communication system, wherein the radio communication system is arranged between the transmission antenna unit and the reception antenna unit so as to form an image with any size of the antenna. In the communication method of the radio | wireless communications system of any one of Claim 6 thru | or 9,
The transmitting station includes an OAM mode selection step of selecting an orbital angular momentum mode to be modulated based on information added to a signal including the data,
The modulation step modulates an electromagnetic wave having the OAM selected in the OAM mode selection step based on a signal including the data,
The communication method of the wireless communication system, wherein the first transmission step radiates an electromagnetic wave having the OAM modulated in the modulation step.

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