Transmitting device and wireless communication system

Abstract

This transmitter device comprises a transmission antenna that transmits an airy beam, and the initial phase distribution that is to be given to an electromagnetic wave transmitted from the transmission antenna is set such that the side lobes of the airy beam are narrow.

Description

[Technical field]

[0001] The present invention relates to a wireless communication technology using Airy Beams. [Background technology]

[0002] Normally, electromagnetic waves have the property of spreading and propagating linearly in the direction of propagation. However, there exists an Airy beam, which has the property of bending its trajectory in one direction by giving an antenna a special initial phase distribution (for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] R. Kadlimatti and PV Parimi, "Millimeter-Wave Nondiffracting Circular Airy OAM Beams," in IEEE Transactions on Antennas and Propagation, vol. 67, no. 1, pp. 260-269, Jan. 2019, doi: 10.1109 / TAP.2018.2876713. Summary of the Invention [Problem to be solved by the invention]

[0004] An Airy beam can be generated by applying a third-order phase change to a two-dimensional plane. However, its trajectory has a 90-degree spread (side lobe) in the x-axis and y-axis directions. Therefore, there is a problem that interference with other beams occurs in the places with this spread.

[0005] The present invention has been made in consideration of the above points, and aims to provide a technique for reducing interference with other beams in wireless communication using Airy beams. [Means for solving the problem]

[0006] According to the disclosed technology, A transmitting antenna for transmitting an Airy beam is provided, A transmitting device in which an initial phase distribution given to an electromagnetic wave transmitted from the transmitting antenna is set so that a side lobe of the Airy beam is narrowed, the transmitting antenna includes a plurality of antennas for Airy beams and at least one antenna for a non-diffracting beam; The non-diffracting beam transmitted by the non-diffracting beam antenna propagates through void regions in the side lobes generated by the Airy beam antennas. A transmitting device is provided. Effect of the Invention

[0007] According to the disclosed technology, it is possible to reduce interference with other beams in wireless communication using Airy beams. [Brief description of the drawings]

[0008] [Figure 1] 1 is a system configuration diagram according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram illustrating an example of the configuration of a transmitting antenna 110. [Diagram 3] FIG. 2 is a diagram illustrating an example of the configuration of a transmitting antenna 110. [Figure 4] FIG. 1 is a diagram for explaining an Airy beam with narrowed side lobes. [Diagram 5] FIG. 13 is a diagram for explaining a term to be added to the equation for generating the phase of an Airy beam. [Figure 6] 1A and 1B are diagrams illustrating an Airy beam and a Bessel beam. [Figure 7] FIG. 1 is a diagram for explaining a first embodiment. [Figure 8] FIG. 1 is a diagram for explaining a first embodiment. [Figure 9] FIG. 11 is a diagram for explaining a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention (the present embodiment) will be described with reference to the drawings. The embodiment described below is merely an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

[0010] (System Configuration) Fig. 1 shows an example of the configuration of a wireless communication system according to the present embodiment. As shown in Fig. 1, the wireless communication system according to the present embodiment includes a transmitting device 100 and a receiving device 200. The transmitting device 100 includes a transmitting antenna 110, a transmitting unit 120, a signal processing unit 130, and a control unit 140. The receiving device 200 includes a receiving antenna 210, a receiving unit 220, a signal processing unit 230, and a control unit 240. For convenience of illustration, the transmitting device 100 and the receiving device 200 are placed close to each other, but in reality they are farther apart.

[0011] 1, the transmitting device 100 and the receiving device 200 are shown separately, but the transmitting device 100 and the receiving device 200 may be provided in one device (device A). In this case, communication is performed between device A and other devices.

[0012] The transmitting antenna 110 in this embodiment can generate an Airy beam whose trajectory has a property of bending in one direction by giving a special initial phase distribution. Specifically, when the antenna is viewed as a two-dimensional plane, the Airy beam can be generated by giving, for example, a third-order phase change to the two-dimensional plane. The receiving antenna 210 may have the same configuration as the transmitting antenna 110, or may be a general antenna that does not have a special configuration for the Airy beam.

[0013] The signal processing unit 130 of the transmitting device 100 generates, from the input data, a digital signal to be transmitted on a carrier wave. The transmitting unit 120 converts the digital signal into an analog signal, converts the frequency of the analog signal into the frequency band of the carrier wave, and outputs the analog signal to the transmitting antenna 110.

[0014] The control unit 140 can perform, for example, phase setting for generating an Airy beam. For example, when the transmitting antenna 110 is a planar antenna consisting of multiple antenna elements, each of which is provided with a variable phase shifter, the control unit 140 instructs each variable phase shifter on the initial phase to be given to the electromagnetic wave.

[0015] In addition, the control unit 140 can determine parameter values ​​for generating an Airy beam based on feedback from the receiving device 200 through processing based on the flow described below, and calculate the initial phase distribution of the transmitting antenna 110 based on the parameter values.

[0016] The transmitting unit 120, the signal processing unit 130, and the control unit 140 may be called a transmitting circuit, a signal processing circuit, and a control circuit, respectively. Moreover, the "signal processing unit 130 and the control unit 140" may be collectively called a processor (or a CPU).

[0017] Furthermore, the control unit 140 may be a computer. The computer includes a memory and a processor, and the processor performs calculations by reading a program stored in the memory. The program may be stored in a recording medium such as a portable memory. The processing performed by the control unit 140 described below may be executed by this program. Note that the control unit 140 may be a device (computer) external to the transmission device 100.

[0018] The receiving unit 220 of the receiving device 200 converts an analog signal received by the receiving antenna 210 into a digital signal and transmits it to the signal processing unit 230. The signal processing unit 230 generates data from the digital signal. The signal processing unit 230 can also perform interference removal processing such as MIMO equalization processing and SIC. The control unit 240 can instruct the signal processing unit 230 whether or not to perform interference removal processing depending on the transmission method of the transmitting antenna 110 (e.g., tolerating a certain degree of interference).

[0019] In addition, the control unit 240 can measure the reception power or reception quality (for example, SINR) of the signal received from the transmitting device 100 and feed back the measurement result to the transmitting device 100.

[0020] The receiving unit 220, the signal processing unit 230, and the control unit 240 may be called a receiving circuit, a signal processing circuit, and a control circuit, respectively. Moreover, the "signal processing unit 230 and the control unit 240" may be collectively called a processor (or a CPU).

[0021] FIG. 2 shows an example of the configuration of a transmitting antenna 110 that generates an Airy beam. FIG. 2 is a front view of the planar transmitting antenna 110. As shown in FIG. 2, the antenna has a configuration in which a plurality of antenna elements (which may be called patch antennas) are provided on a planar substrate. For example, each antenna element has a variable phase shifter, and it is possible to give a predetermined initial phase to the electromagnetic wave (radio wave) for each antenna element. Depending on the initial phase given to each antenna element, it is possible to change the way the side lobes spread and the degree of bending of the Airy beam. The antenna shown in FIG. 2 may be called a multi-element two-dimensional planar array.

[0022] FIG. 3 is a diagram showing another example of the configuration of the transmitting antenna 110 that generates an Airy beam. In this example, the shape of the transmitting antenna 110 as viewed from the front is, for example, circular. FIG. 3 shows an image of a cross section of the transmitting antenna 110 cut along a plane including the axis of the radio wave transmission direction of the transmitting antenna 110. As shown in FIG. 3, the transmitting antenna 110 in this example has an antenna 111 (antenna element) that outputs radio waves, a plane wave generating lens 112, a phase modulation lens 113 (phase modulation plate), and a Fourier transform lens 114. If the plane as viewed from the front of the transmitting antenna 110 is an xy plane, the phase modulation lens can give an initial phase to each point (xy coordinates) on the xy plane. By using a phase modulation lens that realizes a desired initial phase, a desired Airy beam can be generated. In other words, an Airy beam is generated by giving an initial phase change to the electromagnetic wave of a plane wave radiated from the antenna 111 using a phase modulation plate.

[0023] In addition, when using a phase modulation lens to perform wireless communication using Airy beams while gradually changing the parameter values ​​as described below, for example, multiple phase modulation lenses having different initial phase distributions corresponding to the respective parameters are prepared, and wireless communication using Airy beams is performed while exchanging the phase modulation lenses.

[0024] (Airy beam generation method according to the present embodiment) Figures 4(a) and 4(b) show examples of radio wave intensity distribution on a certain plane facing transmitting antenna 110 that generates an Airy beam. Figure 4(a) shows the radio wave intensity distribution of a general Airy beam, and Figure 4(b) shows the radio wave intensity distribution of an Airy beam in an embodiment of the present invention. In Figures 4(a) and (b), the darker the black, the stronger the power.

[0025] As shown in Figure 4(a), a typical Airy beam has a 90-degree spread (side lobes) in the x-axis and y-axis directions around the main lobe, which has strong power. Therefore, interference with other radio waves (beams) occurs in places with this spread.

[0026] On the other hand, the Airy beam of the present embodiment can narrow the side lobe region compared to a general Airy beam, as shown in Fig. 4(b). For example, by utilizing the empty region shown in Fig. 4(b), other beams can be propagated without interference.

[0027] A typical Airy beam shown in Figure 4(a) can be generated by applying an initial phase calculated by the following Equation 1, which represents a typical third-order initial phase distribution for generating an Airy beam, to an electromagnetic wave transmitted from each point (x, y) of the transmitting antenna 110, which is in the xy plane.

[0028] 2πα(x^3+y^3) / 3 Equation 1 In contrast, as shown in Figure 4(b), an Airy beam with a narrower side lobe region can be generated by giving an initial phase calculated by the following equation 2 to the electromagnetic wave transmitted from each point (x, y) of the transmitting antenna 110.

[0029] 2πα(x^3+y^3+ax^2y+bxy^2) / 3 Equation 2 In the above formula 2, a and b are adjustable parameters and are real numbers that satisfy ab<0. However, setting the restriction ab<0 is just an example, and there may be cases where the restriction ab<0 is not set. By using the initial phase distribution calculated by formula 2, it is possible to control the spread of the side lobes in the x-axis and y-axis directions and narrow the area where interference occurs.

[0030] Equation 2 is obtained by adding "ax^2y+bxy^2" to equation 1. The reason why the spread of the side lobes can be narrowed by adding "ax^2y+bxy^2" will be explained below.

[0031] Here, as an example, we consider the case where a = -1 and b = 1. In other words, we consider the case where the term "-x^2y+xy^2" is added to Equation 1 of the initial phase distribution of a conventional Airy beam.

[0032] Figure 5 is a graph of z=-x^2y+xy^2 in xyz space. Adding the term "-x^2y+xy^2" to equation 1 is equivalent to adding a lens with a height distribution as shown in Figure 5 to a transmitting antenna that generates an Airy beam with the initial phase distribution of equation 1.

[0033] Regarding the distribution of the lens height, the absolute value of z increases the further away from the origin along the y=-x axis. In contrast, it can be said that the light is more focused from the wave where the absolute value of z is large toward the wave where the absolute value of z is small. If this is applied to the Airy beam shown in Figure 4(a), the electromagnetic wave will be distributed as being focused toward the y=x axis where the absolute value of z is small, and the side lobe region will be narrowed.

[0034] Below, examples 1 and 2 will be described as more specific examples.

[0035] Example 1 In the first embodiment, a wireless communication system that makes use of the characteristics of the Airy Beam described above will be described.

[0036] As shown in FIG. 4(b), in the Airy beam of this embodiment, the area of ​​the side lobe region can be narrowed, allowing other beams to propagate through the open region without interference.

[0037] Taking advantage of this feature, it is possible to realize wireless communication using both Airy beams and Bessel beams at the same time, as shown in Figure 6. Note that a Bessel beam is a type of non-diffracting beam that does not spread due to the diffraction phenomenon.

[0038] Fig. 7 shows the configuration of the transmitting antenna 110 and the receiving antenna 210 in the wireless communication system in the embodiment 1. As shown in Fig. 7, the transmitting antenna 110 has an antenna 111 for an Airy beam capable of transmitting an Airy beam, and an antenna 112 for a non-diffraction beam capable of transmitting a non-diffraction beam. By utilizing the bending characteristics of the Airy beam, the antenna 112 for a non-diffraction beam can be disposed in front of the antenna 111 for an Airy beam in this manner.

[0039] The Airy beam antenna 111 is equipped with sub-transmitting antennas #1 to #4 each capable of transmitting an Airy beam. Each sub-transmitting antenna of the Airy beam antenna 111 has, for example, the configuration shown in Fig. 2 or the configuration shown in Fig. 3. As antennas facing the sub-transmitting antennas #1 to #4 of the Airy beam antenna 111, the receiving antenna 210 is equipped with sub-receiving antennas #1 to #4.

[0040] Furthermore, the non-diffraction beam antenna 112 has sub-transmitting antennas #1 to #4 each capable of transmitting a non-diffraction beam. As antennas facing the sub-transmitting antennas #1 to #4 of the non-diffraction beam antenna 112, the receiving antenna 210 includes sub-receiving antennas #1 to #4.

[0041] 7, an Airy beam is transmitted from each sub-transmitting antenna of the Airy beam antenna 111, and the corresponding sub-receiving antenna receives it. A non-diffracting beam is transmitted from each sub-transmitting antenna of the non-diffracting beam antenna 112, and the corresponding sub-receiving antenna receives it.

[0042] Each non-diffracting beam is propagated by utilizing the empty area resulting from the narrowing of the side lobes as shown in FIG. 4(b). Therefore, no interference occurs between the non-diffracting beams and the side lobes. FIG. 8 shows the intensity distribution of radio waves at a cross section between the transmitting antenna 110 and the receiving antenna 210 in FIG. 7. As shown in FIG. 7, strong radio waves due to non-diffracting beams propagating through the empty areas are shown as four dots.

[0043] According to the second embodiment, the receiving device 200 does not need to perform equalization processing or interference removal processing such as SIC, and it is possible to realize spatial multiplexing transmission using both the Airy beam and the non-diffraction beam.

[0044] Example 2 In the above-mentioned equation 2, for example, a=0, b=0 are set as the initial values, and the values ​​of a and b are gradually changed. At each stage, the initial phase obtained by equation 2 after changing a and b is given to the transmitting antenna 110, thereby making it possible to gradually change the area (size) of the region in which the side lobes exist.

[0045] When a and b are changed in stages to narrow the area of ​​the region where the side lobes exist, the energy concentrated in the main lobe decreases with the change in a and b. As a result, the radio wave strength of the main lobe decreases, and the received power (or reception quality) at the receiving side decreases.

[0046] Therefore, in the second embodiment, the values ​​of a and b that obtain the desired reception power / reception quality are determined by feeding back the reception power / reception quality from the receiving device 200 to the transmitting device 100. Note that an index indicating the quality of the reception state, such as the reception power, reception quality, or SINR, is called a reception state index, and the value may be called a reception state index value.

[0047] A specific processing example will be described with reference to the flowchart in FIG. 9. It is assumed here that an equation such as "2πα(x^3+y^3-ax^2y+bxy^2) / 3" is used as equation 2, and both a and b are increased stepwise within a range of numbers equal to or greater than 0. As a and b are increased, the free area of ​​the side lobe becomes wider, but the reception strength of the main lobe decreases. This assumption is merely an example. Both a and b may be changed within a range between negative and positive values.

[0048] Moreover, here, the control of the flow shown in Fig. 9 is performed by the control unit 140 of the transmitting device 100 and the control unit 240 of the receiving device 200 in the wireless communication system shown in Fig. 1. However, this is just one example, and devices external to the transmitting device 100 and the receiving device 200 may also control the flow shown in Fig. 9. Also, although SINR is used as the reception state index, this is also just one example.

[0049] In addition, here, the configuration of the transmitting antenna 110 is assumed to be a configuration of multiple antenna elements as shown in Fig. 2, and it is assumed that the phase can be changed arbitrarily by a variable phase shifter. However, the processing of the flow in Fig. 9 can also be executed with the configuration shown in Fig. 3. In the case of the configuration shown in Fig. 3, it is sufficient to replace the phase modulation plate every time a and b are changed.

[0050] In addition, in the flow shown in Figure 9, it is assumed that a and b are changed by the same value, but this is also an example. It is also possible to fix a, change b in all steps, then change a to the next step, and change b in all steps, and repeat this process.

[0051] In S1 (step 1) of FIG. 9, the control unit 140 sets a and b to initial values ​​a=0 and b=0.

[0052] In S2, the control unit 140 sets the initial phase distribution obtained from Equation 2 given the current a and b to the transmitting antenna 110, and causes the transmitting antenna 110 to transmit an Airy beam. The control unit 240 of the receiving device 200 measures the receiving SINR of the main lobe (e.g., 20 dB) and feeds back the measured receiving SINR to the control unit 140 of the transmitting device 100.

[0053] In S3, the control unit 140 judges whether the SINR of the main lobe is at a receivable level. If it is at a receivable level, the process proceeds to S4, and if it is not at a receivable level, the process proceeds to S5. The judgment of whether the SINR of the main lobe is at a receivable level can be made by comparing the SINR with a threshold value.

[0054] In S4, the control unit 140 increases the values ​​of a and b by a fixed amount, performs S2 using the increased values ​​of a and b, and performs the determination in S3. S2, S3, and S4 are repeated while the SINR of the main lobe is at a receivable level.

[0055] If it is determined in S3 that the SINR of the main lobe is not at a receivable level, the process proceeds to S5. In S5, the control unit 140 determines the previous values ​​of a and b as the values ​​of a and b to be used.

[0056] For example, suppose the receivable SINR in the target wireless communication system is 5 dB. In other words, the threshold is 5 dB. When a and b are increased by 0.1 each time, if a=2.5, b=2.5 gives SINR=5.1 dB, and a=2.6, b=2.6 gives SINR=4.9 dB, then the values ​​of a and b are determined to be a=2.5, b=2.5.

[0057] The initial value, the increment value, and the receivable SINR may be set from an external device to the control unit 140. The receivable SINR may be measured by transmitting a known signal from the transmitting device 100 using an Airy beam and having the receiving device 200 measure the known signal.

[0058] The above flow example is a flow based on a policy of expanding the free space of the side lobe as much as possible within the range that can be received on the receiving side.

[0059] (Effects of the embodiment) According to the technology of the embodiment described above, in wireless communication using an Airy beam, it is possible to reduce the area of ​​the side lobes and thereby reduce the area where interference with other beams occurs, thereby increasing the space utilization efficiency.

[0060] (Summary of the first embodiment) This specification discloses at least the following transmitting device and wireless communication system. (Section 1) A transmitting antenna for transmitting an Airy beam is provided, The initial phase distribution given to the electromagnetic wave transmitted from the transmitting antenna is set so that the side lobes of the Airy beam become narrow. Transmitting device. (Section 2) the transmitting antenna includes a plurality of antennas for Airy beams and at least one antenna for a non-diffracting beam; The non-diffracting beam transmitted by the non-diffracting beam antenna propagates through void regions in the side lobes generated by the Airy beam antennas. A transmitting device as described in item 1. (Section 3) The transmitting antenna includes a phase modulation plate, and the initial phase distribution is set by the phase modulation plate. A transmitting device as described in claim 1 or 2. (Section 4) The transmitting antenna includes a plurality of antenna elements, and the initial phase distribution is set by an initial phase given to each of the plurality of antenna elements. A transmitting device as described in claim 1 or 2. (Section 5) The initial phase distribution is calculated by adding a predetermined term to a third-order equation for generating an Airy beam whose side lobes are not narrowed. A transmitting device according to any one of claims 1 to 4. (Section 6) A control unit that controls a shape of a side lobe in an Airy beam transmitted from the transmitting antenna by changing a value of a parameter in the predetermined term. 6. The transmitting device according to claim 5, further comprising: (Section 7) A wireless communication system comprising the transmitting device according to claim 6 and a receiving device, The control unit changes the value of the parameter stepwise, transmits an Airy beam from the transmitting antenna each time the value is changed, receives feedback of a reception state index value of the Airy beam from the receiving device, and determines the value of the parameter based on the feedback. Wireless communication system. (Section 8) The control unit determines, as the parameter value to be used for communication, the value of the parameter at a stage immediately before the reception condition index value becomes worse than the threshold value. 8. A wireless communication system as defined in claim 7.

[0061] Although the present embodiment has been described above, the present invention is not limited to such a specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0062] 100 Transmitting device 110 Transmitting Antenna 120 Transmitter 130 Signal Processing Section 140 Control section 200 Receiving device 210 Receiving antenna 220 Receiving unit 230 Signal Processing Unit 240 Control Unit

Claims

1. A transmitting antenna for transmitting an Airy beam, A transmitting device in which an initial phase distribution given to an electromagnetic wave transmitted from the transmitting antenna is set so that a side lobe of the Airy beam is narrowed, the transmitting antenna includes a plurality of antennas for Airy beams and at least one antenna for a non-diffracting beam; The non-diffracting beam transmitted by the non-diffracting beam antenna propagates through void regions in the side lobes generated by the Airy beam antennas. Transmitting device.

2. The transmitting antenna includes a phase modulation plate, and the initial phase distribution is set by the phase modulation plate. The transmitting device according to claim 1 .

3. A transmitting antenna for transmitting an Airy beam, A transmitting device in which an initial phase distribution given to an electromagnetic wave transmitted from the transmitting antenna is set so that a side lobe of the Airy beam is narrowed, The transmitting antenna includes a plurality of antenna elements, and the initial phase distribution is set by an initial phase given to each of the plurality of antenna elements. Transmitting device.

4. A transmitting antenna for transmitting an Airy beam, A transmitting device in which an initial phase distribution given to an electromagnetic wave transmitted from the transmitting antenna is set so that a side lobe of the Airy beam is narrowed, The initial phase distribution is calculated by adding a predetermined term to a third-order equation for generating an Airy beam whose side lobes are not narrowed. Transmitting device.

5. A control unit that controls a shape of a side lobe in an Airy beam transmitted from the transmitting antenna by changing a value of a parameter in the predetermined term. The transmitting device according to claim 4 , further comprising:

6. A wireless communication system comprising the transmitting device according to claim 5 and a receiving device, The control unit changes the value of the parameter stepwise, transmits an Airy beam from the transmitting antenna each time the value is changed, receives feedback of a reception state index value of the Airy beam from the receiving device, and determines the value of the parameter based on the feedback. Wireless communication system.

7. The control unit determines, as the parameter value to be used for communication, the value of the parameter at a stage immediately before the reception condition index value becomes worse than the threshold value.

7. The wireless communication system according to claim 6.

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