Wireless communication method, wireless communication device, and wireless communication system

Abstract

The wireless communication method according to one embodiment of the present invention involves using a transmission device and a reception device from which it is possible to configure a circular array antenna, in which a plurality of antenna elements are arranged in circular form, wherein the wireless communication method is characterized by including: a collection step for collecting radio wave information received by the circular array antenna of the reception device; and an estimation step for verifying the collected radio wave information against preliminarily collected radio wave information in a plurality of different radio wave transmission states, thereby estimating the axis displacement state of the circular array antennas of the transmission and reception devices.

Description

[Technical field]

[0001] The present invention relates to a wireless communication method, a wireless communication device, and a wireless communication system. [Background technology]

[0002] In recent years, in order to improve the transmission capacity of wireless communication, spatial multiplexing transmission technology of wireless signals using the orbital angular momentum (OAM) of electromagnetic waves has been under study (for example, see Non-Patent Document 1).

[0003] Electromagnetic waves with OAM have equiphase surfaces distributed in a spiral shape along the propagation direction, centered on the propagation axis. In OAM multiplex transmission, electromagnetic waves can have different OAM modes, and propagating in the same direction have orthogonal spatial phase distributions in the direction of the rotation axis. For this reason, in OAM multiplex transmission, signals can be multiplexed and transmitted by separating the signals of each OAM mode modulated with different signal sequences at the receiving device.

[0004] Furthermore, in a wireless communication system using OAM multiplexing technology, a uniform circular array antenna (hereinafter referred to as UCA (Uniform Circular Array)) in which multiple antenna elements are arranged at equal intervals in a circle is used to generate, combine, and transmit multiple OAM modes, thereby achieving spatial multiplexing transmission of different signal sequences (for example, see Non-Patent Document 2). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] J.Wang et al., "Terabit free-space data transmission employing orbital angular momentum multiplexing", Nature Photonics, Vol.6, July 2012, pp.488-496 [Non-Patent Document 2] Y.Yan et al., "High-capacity millimeter-wave communications with orbital angular momentum multiplexing", Nature Commun., vol.5, Sep. 2014, p.4876 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, a transmitting device using UCA can realize high-capacity wireless communication by performing multiplex transmission in a plurality of OAM modes.

[0007] However, in conventional wireless transmission technology using UCA, the transmitting antenna and the receiving antenna must be installed facing each other in order to separate multiple OAM mode signals without interference between the modes, which requires highly accurate axial alignment when installing the UCA.

[0008] In addition, when the number of elements in a receiving antenna is small, the resolution of the radio wave information is reduced, which can lead to a decrease in the accuracy of estimating the axis misalignment. Furthermore, when the receiving antenna is placed far away from the transmission axis of the transmitting antenna, it is difficult to capture the characteristics of OAM because the electromagnetic field distribution that represents OAM cannot be formed at the receiving point of the receiving antenna.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a wireless communication method, wireless communication device, and wireless communication system that can accurately estimate the axial misalignment between the transmission axis and the reception axis when wireless transmission is performed between wireless communication devices that can form a circular array antenna in which multiple antenna elements are arranged in a circle, and enable highly accurate axial alignment. [Means for solving the problem]

[0010] According to one aspect of the present invention, a wireless communication method includes: Multiple concentric, different diameter A wireless communication method using a transmitting device and a receiving device capable of configuring a circular array antenna arranged in a circle, comprising: a collecting step of collecting radio wave information received by the circular array antenna of the receiving device; and an estimating step of estimating an axis misalignment state of the circular array antenna of the transmitting device and the receiving device by comparing the collected radio wave information with radio wave information in a plurality of different radio wave transmission conditions collected in advance. The plurality of different radio wave transmission situations differ in orbital angular momentum mode and combination of the antenna elements to be used, and the radio wave information collected in the collecting step is an electromagnetic field distribution that represents a spatial distribution of the electric field strength and phase of the radio wave. It is characterized by:

[0011] In addition, a wireless communication device according to one aspect of the present invention includes a plurality of antenna elements. Multiple concentric, different diameter A wireless communication device that communicates with another wireless communication device using a circular array antenna arranged in a circle, the wireless communication device comprising: a collection unit that collects radio wave information received by the circular array antenna; and an estimation unit that estimates an axis misalignment state with respect to the circular array antenna provided in the other wireless communication device by comparing radio wave information collected by the collection unit with radio wave information under a plurality of different radio wave transmission conditions that have been collected in advance. The plurality of different radio wave transmission situations differ in orbital angular momentum mode and combination of the antenna elements to be used, and the radio wave information collected by the collection unit is an electromagnetic field distribution that represents a spatial distribution of the electric field strength and phase of the radio wave. It is characterized by:

[0012] In addition, a wireless communication system according to an aspect of the present invention includes a plurality of antenna elements. Multiple concentric, different diameter A wireless communication system for communicating using a transmitting device and a receiving device capable of configuring a circular array antenna arranged in a circle, comprising: a collecting unit that collects radio wave information received by the circular array antenna of the receiving device; and an estimating unit that estimates an axis misalignment state of the circular array antenna of the transmitting device and the receiving device by comparing radio wave information under a plurality of different radio wave transmission conditions collected in advance with the radio wave information collected by the collecting unit. The plurality of different radio wave transmission situations differ in orbital angular momentum mode and combination of the antenna elements to be used, and the radio wave information collected by the collection unit is an electromagnetic field distribution that represents a spatial distribution of the electric field strength and phase of the radio wave. It is characterized by: Effect of the Invention

[0013] According to the present invention, when wireless transmission is performed between wireless communication devices that can constitute a circular array antenna in which multiple antenna elements are arranged in a circle, the axial misalignment between the transmission axis and the reception axis can be accurately estimated, making it possible to achieve highly accurate axial alignment. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of a wireless communication system according to an embodiment. [Diagram 2] 1A and 1B are diagrams illustrating examples of arrangements of a plurality of antenna elements provided in a transmitting device and a receiving device. [Diagram 3] (a) is a diagram illustrating signal generation for OAM mode 0; (b) is a diagram illustrating signal generation for OAM mode 1; (c) is a diagram illustrating signal generation for OAM mode 2; and (d) is a diagram illustrating signal generation for OAM mode 3. [Figure 4] 1A is a diagram illustrating an example of a phase distribution of OAM mode 1. FIG. 1B is a diagram illustrating an example of a phase distribution of OAM mode 2. FIG. 1C is a diagram illustrating an example of a signal intensity distribution in the propagation direction of OAM modes 1 and 2. [Diagram 5] 1 is a diagram showing a state in which the transmission axis of a transmitting device and the reception axis of a receiving device are misaligned. [Figure 6] FIG. 1 is a diagram illustrating an example of an operation of a wireless communication system. [Figure 7] FIG. 11 is a diagram illustrating an overview of another operation example of the wireless communication system. [Figure 8] 2 is a functional block diagram illustrating functions of a receiving device. FIG. [Figure 9] 11 is a flowchart showing a first operation example of the transmitting device. [Figure 10] 11 is a flowchart showing a first operation example of the receiving device. [Figure 11] 13 is a flowchart showing a second operation example of the transmitting device. [Figure 12] 13 is a flowchart showing a second operation example of the receiving device. [Figure 13]13 is a flowchart showing a third operation example of the transmitting device. [Figure 14] 13 is a flowchart showing a third operation example of the receiving device. [Figure 15] 13 is a flowchart showing a fourth operation example of the transmitting device. [Figure 16] 13 is a flowchart showing a fourth operation example of the receiving device. [Figure 17] 10 is a sequence diagram illustrating an operation of the wireless communication system for correcting an axis shift using image information and azimuth information. [Figure 18] 11 is a sequence diagram illustrating another operation of the wireless communication system for correcting an axis shift using image information and azimuth information. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An embodiment of a wireless communication system will be described below with reference to the drawings. FIG. 1 is a diagram showing an example of the configuration of a wireless communication system 1 according to an embodiment. The wireless communication system 1 includes, for example, a transmitting device (transmitting station) 2, a receiving device (receiving station) 3, and a control device (control station) 4, and is configured so that the transmitting device 2 and the receiving device 3 perform OAM multiplex communication using UCA. For example, the transmitting device 2 and the receiving device 3 can configure a circular array antenna in which multiple antenna elements are arranged in a circle, and perform, for example, OAM multiplex transmission using the circular array antenna. Note that the transmitting device 2 and the receiving device 3 may be provided with concentric UCAs with different diameters to perform OAM-MIMO (Multi-Input Multi-Output) communication.

[0016] The transmitting device 2 and the receiving device 3 may be wireless communication devices having the same configuration, for example, with a transmitting function and a receiving function, respectively. The control device 4 transmits a control signal to each of the transmitting device 2 and the receiving device 3. However, the wireless communication system 1 may be configured not to include an independent control device 4.

[0017] 2 is a diagram showing an example of the arrangement of multiple antenna elements in a transmitting device 2 and a receiving device 3. The transmitting device 2 and the receiving device 3 have a circular array antenna (e.g., UCA) in which multiple antenna elements 200 are arranged in a circle, and perform OAM multiplex communication. Note that the UCA may have multiple antenna elements 200 arranged in one circle, or may have multiple antenna elements 200 arranged in multiple concentric circles with different diameters.

[0018] Fig. 3 is a diagram showing an example of phase setting of the UCA for generating signals of OAM modes. Fig. 3(a) is a diagram showing signal generation of OAM mode 0. Fig. 3(b) is a diagram showing signal generation of OAM mode 1. Fig. 3(c) is a diagram showing signal generation of OAM mode 2. Fig. 3(d) is a diagram showing signal generation of OAM mode 3. Here, the UCA is shown to have eight antenna elements 200. The appended numbers indicate phase differences with respect to a reference phase (0°) signal.

[0019] In Fig. 3, the signals of OAM modes 0, 1, 2, 3, ... on the transmitting side are generated by the phase difference of the signals supplied to each antenna element (indicated by a black circle ●) of the UCA. In other words, the signal of OAM mode n is generated by setting the phase of the signal supplied to each antenna element so that the phase rotates n times (n x 360 degrees).

[0020] For example, when a UCA is composed of m = 8 antenna elements, when generating a signal of OAM mode n = 2, a phase difference of 360n / m = 90 degrees (0 degrees, 90 degrees, 180 degrees, 270 degrees, 0 degrees, 90 degrees, 180 degrees, 270 degrees) is set counterclockwise for each antenna element so that the phase rotates twice, as shown in Figure 3(c).

[0021] Note that a signal with the phase rotation direction reversed to that of an OAM mode n signal is called OAM mode -n. For example, the phase rotation direction of a positive OAM mode signal is counterclockwise, and the phase rotation direction of a negative OAM mode signal is clockwise.

[0022] In OAM multiplexing communication, different signal sequences are generated as signals in different OAM modes, and the generated signals are transmitted simultaneously, enabling wireless communication using spatial multiplexing.

[0023] In order for the receiving device 3 to separate the OAM multiplexed signal, the phase of each antenna element of the UCA of the receiving device 3 needs to be set to be in the opposite direction to the phase of the antenna elements of the transmitting device 2.

[0024] Fig. 4 is a diagram illustrating the phase distribution and signal intensity distribution of an OAM multiplexed signal. Fig. 4(a) is a diagram illustrating the phase distribution of OAM mode 1. Fig. 4(b) is a diagram illustrating the phase distribution of OAM mode 2. Fig. 4(c) is a diagram illustrating the signal intensity distribution in the propagation direction of OAM modes 1 and 2.

[0025] In Figures 4(a) and (b), the arrows indicate the phase distribution of the signal as seen from the end face (orthogonal propagation plane) perpendicular to the propagation direction from the transmitter 2. The arrows start at 0 degrees. The phase changes linearly. The arrows end at 360 degrees. In other words, a signal in OAM mode n propagates while its phase rotates by n (n x 360 degrees) on the orthogonal propagation plane. Note that the arrows of the phase distribution of signals in OAM modes -1 and -2 point in opposite directions.

[0026] The signal intensity distribution of each OAM mode differs. In other words, the position where the signal intensity observed on a plane perpendicular to the propagation axis (propagation direction) is maximum differs for each OAM mode. However, the intensity distribution of the same OAM mode with a different sign is the same. Specifically, the higher the OAM mode, the farther the position where the signal intensity is maximum is from the propagation axis (see Non-Patent Document 2). Here, the OAM mode with a larger value is called a higher order mode. For example, a signal of OAM mode 3 is a higher order mode than a signal of OAM mode 0, OAM mode 1, or OAM mode 2.

[0027] In Fig. 4(c), the position where the signal strength is maximum for each OAM mode is shown as a circle. As the OAM mode becomes higher order, the position where the signal strength is maximum becomes farther from the central axis, and the beam diameter of the OAM mode multiplexed signal expands depending on the propagation distance, so that the circle showing the position where the signal strength is maximum for each OAM mode becomes larger.

[0028] As described above, using UCA to perform OAM multiplex transmission enables high-capacity wireless communication, but in order to separate signals of multiple OAM modes without interference between the modes, it is necessary to install the transmitting antenna and the receiving antenna in positions facing each other. In general, the transmitting axis of the transmitting device 2 and the receiving axis of the receiving device 3 are aligned by trial and error while checking the received power and transmission throughput, but it is not easy to achieve the high-precision axis alignment required for OAM multiplex transmission, for example.

[0029] For example, as shown in FIG. 5, if the transmission axis of the transmitter 2 and the reception axis of the receiver 3 are misaligned, the receiving antenna of the receiver 3 cannot form an electromagnetic field distribution that represents OAM.

[0030] Therefore, the wireless communication system 1 according to the present embodiment is configured to estimate the axis misalignment between the transmission axis of the transmitter 2 and the reception axis of the receiver 3, and correct the axis misalignment based on the estimation result.

[0031] Fig. 6 is a diagram showing a schematic overview of an operation example of the wireless communication system 1. As shown in Fig. 6, for example, the receiving device 3 receives, by using the UCA, radio waves in a designated OAM mode transmitted by the transmitting device 2 using the UCA. The receiving device 3 then compares the received radio wave information of one or more OAM modes (received power and phase patterns of each element of the UCA and received power and phase patterns after separation into each mode) with an electromagnetic field distribution database (DB) 30, thereby estimating the distance between the transmitting device 2 and the receiving device 3, the direction of the antenna aperture, and the axial shift.

[0032] The DB 30 is a database that stores radio wave information in a plurality of different radio wave transmission conditions that have been collected or calculated in advance. Here, the DB 30 is provided in the receiving device 3, but may be provided in the control device 4 (see FIG. 1) or the like.

[0033] Then, for example, the receiving device 3 controls the position, orientation, and beam direction of the receiving antenna based on the estimated axis deviation, and performs axis alignment.

[0034] FIG. 7 is a diagram showing a schematic overview of another operation example of the wireless communication system 1. For example, the transmitting device 2 switches between a plurality of different radio waves and transmits them to the receiving device 3 while switching (selecting) different antenna elements such as OAM mode switching and concentric UCAs with different diameters. The OAM mode or UCA (antenna element) to be switched (selected) here does not need to match those actually used for communication. For example, in OAM multiplex communication, one or more high-order OAM modes that do not meet the SNR required by the desired modulation method may be used for estimating the axis shift described in the present invention. In addition, in a wireless communication system that assumes non-OAM multiplex communication (general communication using only mode 0), one or more high-order OAM modes may be used for estimating the axis shift described in the present invention. In addition, the wireless communication system 1 may select antenna elements that constitute a UCA from the antenna elements 200 included in the transmitting device 2 and the receiving device 3 only when estimating the axis shift.

[0035] The receiving device 3 estimates the distance between the transmitting device 2 and the receiving device 3, the direction of the antenna aperture, and the amount of axis misalignment by comparing the received radio wave information with radio wave information in a plurality of different radio wave transmission conditions that have been collected or calculated in advance. The receiving device 3 can increase the amount of radio wave information to be compared by the transmitting device 2 switching the OAM mode and switching between UCAs with different concentric diameters, i.e., different antenna elements, and performs synthesis and correction processing on the amount of axis misalignment estimated from each piece of radio wave information by appropriate means such as weighting based on the maximum reception strength or average SNR or averaging processing. Therefore, the receiving device 3 can improve the accuracy of the amount of axis misalignment compared to estimating it from a single piece of radio wave information.

[0036] Thereafter, the receiving device 3 performs position correction (horizontal direction, vertical direction, transmission axis direction) and angle correction (horizontal direction, vertical direction) of the receiving device 3 based on the estimated axis shift to eliminate the axis shift. Furthermore, the receiving device 3 may perform correction based on the channel response for each mode, inter-mode interference, etc. Also, the receiving device 3 performs feedback of the amount of axis shift to the transmitting device 2 or the control device 4.

[0037] In this way, in the wireless communication system 1, the transmitting device 2, the receiving device 3, or the control device 4 estimates the amount of axis shift between the transmitting device 2 and the receiving device 3, shares the estimated value, and corrects the transmitting axis and the receiving axis based on the estimated amount of axis shift.

[0038] Next, a specific example of the functions of the receiving device 3 will be described. Fig. 8 is a functional block diagram illustrating the functions of the receiving device 3. The transmitting device 2 may also have the same configuration as the receiving device 3 and be configured to perform two-way communication.

[0039] As shown in FIG. 8, the receiving device 3 includes, for example, an electromagnetic field distribution database (DB) 30, a circular array antenna 31, a transmitting / receiving unit 32, a collecting unit 33, an estimating unit 34, a correcting unit 35, a setting unit 36, a control signal acquiring unit 37, a database (DB) generating unit 38, an image acquiring unit 40, an orientation acquiring unit 41, an analyzing unit 42, an axis deviation amount calculating unit 43, and an adjustment amount calculating unit 44.

[0040] As described above, DB30 is a database that stores radio wave information in a plurality of different radio wave transmission situations that have been collected or calculated in advance. For example, the radio wave information is an electromagnetic field distribution (electromagnetic field distribution characteristic data) that indicates the spatial distribution of the electric field strength and phase of radio waves, and is information that is generated by varying at least one of the OAM mode and the antenna element 200. In addition, the plurality of different radio wave transmission situations are generated by, for example, varying at least one of the orbital angular momentum mode and the antenna element. In addition, the plurality of different radio wave transmission situations also include an OAM mode that is not used for communication for data transmission.

[0041] Circular array antenna 31 is a UCA in which multiple antenna elements are arranged in a circle, and multiple antenna elements 200 (see FIG. 2) may be arranged in one circle, or multiple antenna elements 200 may be arranged in multiple circles with different diameters and concentric about a center. Also, circular array antenna 31 can be used for both transmitting and receiving radio waves, for example, but may be divided into a transmitting antenna and a receiving antenna.

[0042] The transmitting / receiving unit 32 transmits and receives radio waves via the circular array antenna 31 in accordance with settings made by a setting unit 36, which will be described later.

[0043] The collection unit 33 collects radio wave information received by the circular array antenna 31, and outputs it to the estimation unit 34 and the setting unit 36. The radio wave information collected by the collection unit 33 is, for example, the electric field intensity and phase of the received radio wave for each OAM mode and for each antenna element, and an electromagnetic field distribution that indicates the spatial distribution of the electric field intensity and phase of the received signal after separation for each OAM mode.

[0044] The radio wave information may be expressed in complex numbers to represent the electric field strength and phase. The radio wave information may also be propagation channel information of the received signal for each OAM mode or for each antenna element, or propagation channel information of the received signal after separation for each OAM mode.

[0045] The collecting unit 33 is configured to be able to collect radio wave information again even after the correcting unit 35, which will be described later, corrects the axis misalignment and performs axis alignment.

[0046] The estimation unit 34 compares the radio wave information stored in the DB 30 with the radio wave information collected by the collection unit 33 to estimate the axial misalignment state (such as the angle of the propagation axis) of the circular array antenna 31 of the transmitting device 2 and the receiving device 3, and outputs the result to the correction unit 35. Note that the propagation axis of the circular array antenna 31 is, for example, on a virtual straight line extending from the center of the UCA in a direction perpendicular to the aperture plane, and is the central axis of the electromagnetic field distribution along which each OAM mode is orthogonal to each other.

[0047] The estimation unit 34 also estimates the axis misalignment state of the circular array antenna 31 based on, for example, a plurality of different pieces of radio wave information. For example, the estimation unit 34 may improve the estimation accuracy by performing a process such as combining the amount of axis misalignment estimated using the feature quantities of each of the plurality of different pieces of radio wave information. The estimation unit 34 is also configured to be able to re-estimate the axis misalignment state of the circular array antenna 31 of the transmitting device 2 and the receiving device 3 by collating radio wave information under a plurality of different radio wave transmission conditions collected in advance with the radio wave information collected again by the collecting unit 33.

[0048] The correction unit 35 performs axis alignment by correcting the axis misalignment of the circular array antennas 31 of the transmitting device 2 and the receiving device 3 based on the axis misalignment condition estimated by the estimation unit 34. Note that the correction unit 35 is configured to be able to correct the axis misalignment of the circular array antenna 31 and perform axis alignment based on the axis misalignment condition estimated by the estimation unit 34 again after the correction and axis alignment.

[0049] The correction unit 35 also has a function of correcting the axial misalignment of the circular array antennas 31 of the transmitting device 2 and the receiving device 3 based on the amount of adjustment calculated by an adjustment amount calculation unit 44 described later, to perform axial alignment.

[0050] The setting unit 36 ​​performs settings for the transmitting / receiving unit 32 so that the result of the axis alignment performed by the correcting unit 35 after correcting the axis misalignment is reflected in the circular array antenna 31.

[0051] The control signal acquisition unit 37 acquires a control signal transmitted by, for example, the transmission device 2, and outputs it to the database generation unit 38. The control signal includes parameters for generating and transmitting an OAM mode multiplexed signal.

[0052] Based on the control signal acquired by the control signal acquisition unit 37 and the radio wave information collected by the collection unit 33, the database generation unit 38 generates radio wave information to be stored in DB30, such as an electromagnetic field distribution representing the spatial distribution of the electric field strength and phase of the radio waves, and outputs it to DB30.

[0053] The image acquisition unit 40 is, for example, a camera, acquires an image (image information) including the transmitting device 2 (or the receiving device 3), and outputs it to the analysis unit 42.

[0054] The direction acquisition unit 41 acquires the direction (direction information) of the location of the transmitting device 2 (or the receiving device 3, in some cases) contained in the image acquired by the image acquisition unit 40, and outputs the direction (direction information) to the analysis unit .

[0055] The analysis unit 42 analyzes the image acquired by the image acquisition unit 40 and the orientation acquired by the orientation acquisition unit 41 , and outputs the analysis result to the axis deviation amount calculation unit 43 .

[0056] The axis shift amount calculation unit 43 calculates the amount of axis shift of the circular array antennas 31 of the transmitting device 2 and the receiving device 3 based on the radio wave information stored in the DB 30 and the results of the analysis by the analysis unit 42, and outputs the calculated amount to the adjustment amount calculation unit 44.

[0057] The adjustment amount calculation unit 44 refers to the radio wave information stored in the DB 30, calculates an adjustment amount for correcting the amount of axis shift calculated by the axis shift amount calculation unit 43, and outputs the amount of adjustment to the correction unit .

[0058] Therefore, in the receiving device 3, the correction unit 35 performs rough adjustment of the axis shift based on the image acquired by the image acquisition unit 40 and the orientation acquired by the orientation acquisition unit 41, and then the receiving device 3 can fine-tune the axis shift of the circular array antennas 31 of the transmitting device 2 and the receiving device 3 based on the axis shift situation estimated by the estimation unit 34.

[0059] Next, a first operation example of the wireless communication system 1 will be described. In the first operation example of the wireless communication system 1, a comparison is performed using the DB 30 included in the receiving device 3. FIG. 9 is a flowchart showing the first operation example of the transmitting device 2. As shown in FIG. 9, the transmitting device 2 first sets the OAM mode (S100). Next, the transmitting device 2 sets the antenna element to be used (S102), generates an OAM mode multiplexed signal, and transmits it to the receiving device 3 (S104).

[0060] Fig. 10 is a flowchart showing a first operation example of the receiving device 3. As shown in Fig. 10, the receiving device 3 receives a QAM mode multiplexed signal (S200), and reads out the electromagnetic field distribution characteristic data from the DB 30 and performs a comparison (S202).

[0061] Then, the receiving device 3 estimates the axis shift between the transmitting device 2 and the receiving device 3 (S204), and calculates a correction amount based on the estimation result (S206). If the calculated correction amount is within a predetermined range (S208: Yes), the receiving device 3 corrects the axis shift of the receiving device 3 and the axis shift of the transmitting device 2 via the control device 4 (S210), and if the calculated correction amount is not within the predetermined range (S208: No), the process ends.

[0062] In this way, the wireless communication system 1 may correct the axis misalignment based on the radio waves received by the receiving device 3. In the following description of an example of the operation of the wireless communication system 1, substantially the same operations are denoted by the same reference numerals.

[0063] Next, a second operation example of the wireless communication system 1 will be described. In the second operation example of the wireless communication system 1, a comparison is performed using the DB 30 included in the transmitting device 2. FIG. 11 is a flowchart showing the second operation example of the transmitting device 2. As shown in FIG. 11, the transmitting device 2 first sets the OAM mode (S100). Next, the transmitting device 2 sets the antenna element to be used (S102), generates an OAM mode multiplexed signal, and transmits it to the receiving device 3 (S104).

[0064] Then, the transmitting device 2 receives radio wave information (feedback information) from the receiving device 3 (S106), and reads out the electromagnetic field distribution characteristic data from the DB 30 and performs a comparison (S202). Note that the feedback information may include accompanying information on the measurement conditions of the receiving device 3 (antenna gain, NF and loss of the RF circuit, etc.).

[0065] Then, the transmitting device 2 estimates the axis shift between the transmitting device 2 and the receiving device 3 (S204), and calculates a correction amount based on the estimation result (S206). If the calculated correction amount is within a predetermined range (S208: Yes), the transmitting device 2 corrects the axis shift of the transmitting device 2 and the axis shift of the receiving device 3 via the control device 4 (S210), and if the calculated correction amount is not within the predetermined range (S208: No), the processing ends.

[0066] Fig. 12 is a flowchart showing a second operation example of the receiving device 3. As shown in Fig. 12, the receiving device 3 receives a QAM mode multiplexed signal (S200), and transmits radio wave information (feedback information) to the transmitting device 2 (S212).

[0067] In this manner, the wireless communication system 1 may correct the axis misalignment based on the feedback information received by the transmitting device 2.

[0068] Next, a third operation example of the wireless communication system 1 will be described. In the third operation example of the wireless communication system 1, a comparison is performed using the DB 30 included in the receiving device 3. FIG. 13 is a flowchart showing the third operation example of the transmitting device 2. As shown in FIG. 13, the transmitting device 2 first sets the OAM mode (S100). Next, the transmitting device 2 sets the antenna element to be used (S102), generates an OAM mode multiplexed signal, and transmits it to the receiving device 3 (S104).

[0069] In addition, the transmitting device 2 determines whether or not there is a retransmission instruction from the receiving device 3 to transmit radio waves (S108), and if there is a retransmission instruction (S108: Yes), proceeds to processing of S110, and if there is no retransmission instruction (S108: No), terminates the processing.

[0070] In the process of S110, the transmitting device 2 transmits the OAM mode multiplexed signal to the receiving device 3.

[0071] Fig. 14 is a flowchart showing a third operation example of the receiving device 3. As shown in Fig. 14, the receiving device 3 receives a QAM mode multiplexed signal (S200), and reads out the electromagnetic field distribution characteristic data from the DB 30 and performs a comparison (S202).

[0072] Then, the receiving device 3 estimates the axis shift between the transmitting device 2 and the receiving device 3 (S204), and calculates a correction amount based on the estimation result (S206). If the calculated correction amount is within a predetermined range (S208: Yes), the receiving device 3 corrects the axis shift of the receiving device 3 and the axis shift of the transmitting device 2 via the control device 4 (S210), and if the calculated correction amount is not within the predetermined range (S208: No), the process ends.

[0073] Furthermore, the receiving device 3 instructs the transmitting device 2 to retransmit the radio wave (S214), and receives the QAM mode multiplexed signal again (S216).

[0074] Then, the receiving device 3 observes the state of axis deviation (S218), calculates the amount of correction based on the observation result (S220), and returns to the process of S208.

[0075] Next, a fourth operation example of the wireless communication system 1 will be described. In the fourth operation example of the wireless communication system 1, a comparison is performed using DB 30 included in the transmitting device 2. Fig. 15 is a flowchart showing the fourth operation example of the transmitting device 2. As shown in Fig. 15, the transmitting device 2 acquires image information and direction information (S300), and performs an analysis process of the image information and the direction information (S302).

[0076] The transmitting device 2 determines whether or not the receiving device 3 has been detected by the analysis process (S304), and if not (S304: No), proceeds to processing of S306, and if detected (S304: Yes), proceeds to processing of S310.

[0077] In the processing of S306, the transmitting device 2 determines whether or not data in 360 degrees of directions has been acquired (S306), and if not (S306: No), proceeds to processing of S308, and if acquired (S306: Yes), terminates the processing.

[0078] In the process of S308, the transmission device 2 changes the image acquisition direction, and proceeds to the process of S300.

[0079] Furthermore, the transmitting device 2 estimates the axis shift in the process of S310, calculates the amount of correction (S312), and then corrects the axis shift of the transmitting device 2 and the axis shift of the receiving device 3 via the control device 4 (S314).

[0080] Next, the transmitting device 2 newly selects an OAM mode (S316), selects an antenna element corresponding to the OAM mode (S318), and transmits an OAM radio wave (S320).

[0081] The transmitter 2 continues the receiving process until it receives feedback information from the receiver 3 (S322), and upon receiving the feedback information, reads data from the DB 30 (S324) and estimates the axis deviation (S326).

[0082] Then, the transmitting device 2 determines whether the electric field strength of the radio wave information exceeds a predetermined threshold (S328), and if it does not exceed it (S328: No), proceeds to processing of S330, and if it exceeds it (S328: Yes), proceeds to processing of S334.

[0083] The transmitting device 2 changes the OAM mode in the process of S330, changes the antenna element so as to correspond to the OAM mode (S332), and returns to the process of S320.

[0084] Furthermore, the transmitting device 2 corrects the axis deviation in the process of S334.

[0085] Fig. 16 is a flowchart showing a fourth operation example of the receiving device 3. As shown in Fig. 16, the receiving device 3 receives an OAM radio wave for axis misalignment correction (S400), and creates a received electric field strength map as feedback information (S402). Then, the receiving device 3 transmits the feedback information to the transmitting device 2 (S404).

[0086] That is, in the fourth operation example, the wireless communication system 1 receives feedback information and corrects the axis shift again after the transmitting device 2 corrects the axis shift based on the image information and the direction information.

[0087] 17 is a sequence diagram illustrating an operation of correcting an axis shift using image information and direction information in the wireless communication system 1. As shown in FIG 17, the transmitting device 2 acquires image information together with direction information (t1), and performs, for example, image recognition processing as an analysis processing to detect the receiving device 3 (t2).

[0088] The transmitting device 2 calculates the amount of axis shift in the horizontal and vertical directions using the direction of its own station and the detected direction information of the receiving device 3 (t3), and adjusts the attitude of the device (e.g., the transmitting device 2) in the horizontal and vertical directions based on the calculated amount of axis shift (t4). In other words, the transmitting device 2 performs a rough adjustment of the axis shift using the image information and the direction information.

[0089] Next, the transmitting device 2 transmits OAM radio waves to the receiving device 3 using a specific mode and antenna element (t5), and causes the receiving device 3 to feed back the received OAM radio waves as they are (t6).

[0090] Then, the transmitting device 2 compares the transmission radio wave information or the radio wave information of the DB 30 with the feedback information to calculate the amount of axis misalignment (t7), and adjusts the antenna direction and antenna element (t8). That is, the transmitting device 2 performs fine adjustment of the axis misalignment using the feedback information from the receiving device 3. Thereafter, the transmitting device 2 performs OAM multiplex transmission with the receiving device 3.

[0091] Fig. 18 is a sequence diagram illustrating another operation of correcting the axis shift by using image information and direction information in the wireless communication system 1. As shown in Fig. 18, the transmitting device 2 acquires image information together with direction information (t1), and performs, for example, image recognition processing as an analysis processing to detect the receiving device 3 (t2).

[0092] The transmitting device 2 calculates the amount of axis shift in the horizontal and vertical directions using the direction of its own station and the detected direction information of the receiving device 3 (t3), and adjusts the attitude of the device (e.g., the transmitting device 2) in the horizontal and vertical directions based on the calculated amount of axis shift (t4). In other words, the transmitting device 2 performs a rough adjustment of the axis shift using the image information and the direction information.

[0093] Next, the transmitting device 2 transmits OAM radio waves to the receiving device 3 using a specific mode and antenna element (t5).

[0094] Then, the receiving device 3 compares the transmitted radio wave information or the radio wave information of the DB 30 with the received radio wave information to calculate the amount of axis misalignment (t6), adjusts the antenna direction and antenna elements (t7), and transmits an adjustment completion notification to the transmitting device 2 (t8). In other words, the receiving device 3 performs fine adjustment of the axis misalignment using the received radio wave information. Thereafter, the transmitting device 2 performs OAM multiplex transmission with the receiving device 3.

[0095] In this way, the wireless communication system 1 according to the embodiment can estimate the axis misalignment state of the circular array antenna 31 of the transmitting device 2 and the receiving device 3 by comparing the collected radio wave information with radio wave information in a plurality of different radio wave transmission conditions collected in advance. The wireless communication system 1 can estimate the axis misalignment and perform axis alignment of the circular array antenna 31 by using the characteristics of OAM, but can also estimate the axis misalignment and perform axis alignment for communications other than OAM communications. The wireless communication system 1 may estimate the axis misalignment and perform axis alignment by using one or more OAM modes that are not used for communications. For example, the wireless communication system 1 may use a high-order mode of OAM mode 1 or higher for non-OAM communications, and a high-order mode with a low SNR that cannot be used for communications for OAM communications. When the wireless communication system 1 uses UCA, the number of modes that can be reproduced is limited by the number of antenna elements, but in principle, any high-order OAM mode can be generated and can be combined and compared with a database of radio wave information corresponding to each OAM mode.

[0096] In other words, when orbital angular momentum multiplexing transmission is performed using a circular array antenna in which multiple antenna elements are arranged in a circle, the wireless communication system 1 can accurately estimate the axial misalignment between the transmitting axis and the receiving axis, enabling highly accurate axial alignment.

[0097] In addition, each of the components constituting the transmitting device 2, the receiving device 3, and the control device 4 in the above-mentioned embodiments may be configured in part or in whole by hardware, or may be configured by having a processor execute a program.

[0098] Furthermore, when each part constituting the transmitting device 2, the receiving device 3 and the control device 4 is constituted in part or in whole by having a processor execute a program, the program may be recorded on a recording medium and supplied, or may be supplied via a network.

[0099] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims. In addition, the above-mentioned multiple embodiments may be combined. [Explanation of symbols]

[0100] 1 wireless communication system, 2 transmitting device, 3 receiving device, 4 control device, 30 DB, 31 circular array antenna, 32 transmitting / receiving unit, 33 collecting unit, 34 estimating unit, 35 correcting unit, 36 setting unit, 37 control signal acquiring unit, 38 database generating unit, 40 image acquiring unit, 41 direction acquiring unit, 42 analyzing unit, 43 axis deviation calculating unit, 44 adjustment calculating unit, 200 antenna element

Claims

1. A wireless communication method using a transmitting device and a receiving device capable of configuring a circular array antenna in which a plurality of antenna elements are arranged in a plurality of concentric circles with different diameters, comprising: a collecting step of collecting radio wave information received by the circular array antenna of the receiving device; an estimation step of estimating an axis misalignment state of the circular array antenna of the transmitting device and the receiving device by comparing the collected radio wave information with radio wave information in a plurality of different radio wave transmission states collected in advance; Including, The plurality of different radio wave transmission conditions include: The orbital angular momentum modes and the combinations of the antenna elements used are different, The radio wave information collected in the collecting step is It is an electromagnetic field distribution that represents the spatial distribution of the electric field strength and phase of radio waves. A wireless communication method comprising:

2. The plurality of different radio wave transmission conditions include: Including orbital angular momentum modes that are not used for data transmission communications.

2. The wireless communication method according to claim 1,

3. The radio wave information is The information is generated by changing the orbital angular momentum mode and the combination of the antenna elements to be used, In the estimation step, Estimating the axis misalignment state of the circular array antenna based on a plurality of different pieces of radio wave information.

3. The wireless communication method according to claim 1 or 2,

4. The method further includes a correction step of correcting the axis misalignment of the circular array antennas of the transmitting device and the receiving device based on the axis misalignment state estimated in the estimation step, thereby performing axis alignment. The wireless communication method according to any one of claims 1 to 3,

5. After the axis misalignment is corrected and the axis is aligned in the correction step, radio wave information is collected again. re-estimating the axis misalignment state of the circular array antenna of the transmitting device and the receiving device by comparing the radio wave information collected again with radio wave information collected in advance under a plurality of different radio wave transmission conditions; Based on the estimated axis deviation state again, the axis deviation of the circular array antenna of the transmitting device and the receiving device is corrected to perform axis alignment.

5. The wireless communication method according to claim 4,

6. an image acquisition step of acquiring an image including the transmitting device or the receiving device; an orientation acquisition step of acquiring an orientation of the transmitting device or the receiving device included in the acquired image; an axial misalignment amount calculation step of calculating an axial misalignment amount of the circular array antennas of the transmitting device and the receiving device based on the acquired image and the acquired direction; a correction step of correcting the axial misalignment of the circular array antennas of the transmitting device and the receiving device based on the calculated amount of axial misalignment, and Further comprising: The collecting step includes: After correcting the axis misalignment and performing axis alignment in the correction step, radio wave information is collected; The estimation step includes: and estimating an axis misalignment state of the circular array antenna of the transmitting device and the receiving device by comparing radio wave information collected in the collecting step with radio wave information in a plurality of different radio wave transmission states collected in advance.

2. The wireless communication method according to claim 1,

7. Based on the axis deviation state estimated in the estimation step, the axis deviation of the circular array antennas of the transmitting device and the receiving device is corrected again to perform axis alignment.

7. The wireless communication method according to claim 6,

8. A wireless communication device that communicates with another wireless communication device using a circular array antenna in which a plurality of antenna elements are arranged in multiple circles with different diameters and concentrically, a collection unit for collecting radio wave information received by the circular array antenna; an estimation unit that estimates an axis misalignment state with respect to a circular array antenna provided in the other wireless communication device by comparing radio wave information in a plurality of different radio wave transmission states that have been collected in advance with the radio wave information collected by the collection unit; having The plurality of different radio wave transmission conditions include: The orbital angular momentum modes and the combinations of the antenna elements used are different, The radio wave information collected by the collection unit is It is an electromagnetic field distribution that represents the spatial distribution of the electric field strength and phase of radio waves. A wireless communication device comprising:

9. A wireless communication system that uses a transmitting device and a receiving device capable of configuring a circular array antenna in which a plurality of antenna elements are arranged in multiple concentric circles with different diameters, a collection unit that collects radio wave information received by the circular array antenna of the receiving device; an estimation unit that estimates an axis misalignment state of the circular array antenna of the transmitting device and the receiving device by comparing radio wave information under a plurality of different radio wave transmission conditions that have been collected in advance with the radio wave information collected by the collection unit; having The plurality of different radio wave transmission conditions include: The orbital angular momentum modes and the combinations of the antenna elements used are different, The radio wave information collected by the collection unit is It is an electromagnetic field distribution that represents the spatial distribution of the electric field strength and phase of radio waves. A wireless communication system comprising:

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