TRANSMISSION CONTROL DEVICE, WIRELESS COMMUNICATION SYSTEM, TRANSMISSION CONTROL METHOD, AND PROGRAM

Abstract

Provided is a transmission control device that is provided with: a communication characteristic information acquisition unit for acquiring communication characteristic information indicating a communication characteristic; a power control method determination unit for determining, on the basis of the communication characteristic information, a power control method for a transmission signal, said method using power up to a third threshold value which is a threshold value between a predefined first threshold value and second threshold value; and a signal processing control unit for using the determined power control method to generate a transmission signal.

Description

[Technical field]

[0001] The present invention relates to a technique for spatially multiplexing and transmitting wireless signals using the orbital angular momentum (OAM) of electromagnetic waves. [Background technology]

[0002] In recent years, in order to improve transmission capacity, spatial multiplexing transmission technology of radio signals using OAM has been studied (for example, Non-Patent Document 1). In electromagnetic waves with OAM, equiphase surfaces are distributed in a spiral shape along the propagation direction centered on the propagation axis. Since electromagnetic waves with different OAM modes propagating in the same direction have orthogonal spatial phase distributions in the direction of the rotation axis, it is possible to multiplex and transmit signals by separating the signals of each OAM mode modulated with different signal sequences at the receiving device.

[0003] In a wireless communication system using this 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 realizing spatial multiplexing transmission of different signal sequences (for example, Non-Patent Document 2). For example, a Butler circuit (Butler matrix circuit) is used to generate and separate signals for the multiple OAM modes. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] J.Wang et al., "Terabit free-space data transmission employing orbital angular momentum multiplexing," Nature Photonics, Vol.6, pp.488-496, July 2012. [Non-Patent Document 2] Y.Yan et al., "High-capacity millimeter-wave communications with orbital angular momentum multiplexing," Nature Commun., vol.5, p.4876, Sep. 2014. Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, a transmitter using UCA and a Butler circuit enables large-capacity communications, but in the future, it will be necessary to utilize higher frequency bands and extend transmission distances.

[0006] However, with conventional wireless transmission technologies, communication devices that transmit signals in high frequency bands such as sub-THz are more susceptible to power drops in their output signals than communication devices that transmit signals in frequency bands such as microwaves. As a result, it becomes difficult to ensure a sufficient receiving SNR as the transmission distance increases, resulting in a deterioration in communication quality.

[0007] The disclosed technology aims to improve communication quality in wireless communication in high frequency bands. [Means for solving the problem]

[0008] The disclosed technology includes a communication characteristic information acquisition unit that acquires communication characteristic information indicating communication characteristics, a power control method determination unit that determines a power control method for a transmission signal with power up to a third threshold value that is a threshold value between a first threshold value and a second threshold value that are predefined based on the communication characteristic information, and a signal processing control unit that generates a transmission signal using the determined power control method. The communication characteristic information includes any one of a transmission / reception distance, a desired multi-level modulation number, a peak-to-average power ratio of a signal, characteristics of the region from the first threshold to the second threshold in the communication device, the SNR of a received signal, and an error vector amplitude of the received signal, and the power control method determination unit determines, by a calculation based on the transmission / reception distance, whether the SNR will be a value that allows the desired multi-level modulation number to be achieved even if the transmission power is set to below the first threshold, based on association information that indicates the association between the SNR of the received signal and the multi-level modulation number, and if it is determined that the SNR will be a value that allows the desired multi-level modulation number to be achieved, controls the power of the transmission signal to be below the first threshold, and if it is determined that the SNR will not be a value that allows the desired multi-level modulation number to be achieved, controls the power of the transmission signal to be below the third threshold. Effect of the Invention

[0009] The communication quality in high-frequency band wireless communication can be improved. [Brief description of the drawings]

[0010] [Figure 1] FIG. 13 is a diagram illustrating an example of phase setting of a UCA for generating an OAM mode signal. [Diagram 2] 1A to 1C are diagrams illustrating examples of phase distribution and signal intensity distribution of an OAM multiplexed signal. [Diagram 3] 1 is a configuration diagram of a communication system according to an embodiment of the present invention. [Figure 4] FIG. 1 is a diagram for explaining a power control method according to a conventional technique. [Diagram 5] 1 is a diagram for explaining a power control method according to an embodiment of the present invention. [Figure 6] FIG. 2 illustrates an example of the configuration of a transmitting device. [Figure 7] 1 is a diagram showing an example of a connection configuration between a Butler circuit and an antenna element in a transmitting device. [Figure 8] FIG. 2 is a diagram illustrating an example of a functional configuration of a transmission control device. [Figure 9] 13 is a flowchart showing an example of the flow of a transmission control process. [Figure 10] FIG. 2 is a diagram illustrating an example of the configuration of a receiving device. [Figure 11] 1 is a diagram showing an example of a connection configuration between a Butler circuit and an antenna element in a receiving device; [Figure 12] FIG. 2 is a diagram illustrating an example of a functional configuration of a reception control device. [Figure 13] FIG. 1 is a diagram for explaining a conventional demodulation method for a nonlinear signal. [Figure 14] 13 is a flowchart showing an example of the flow of a reception control process. [Figure 15] FIG. 1 is a diagram for explaining a method for demodulating a received signal according to the prior art. [Figure 16] 1 is a diagram for explaining a method for demodulating a received signal according to an embodiment of the present invention. [Figure 17] FIG. 2 illustrates an example of a hardware configuration of a computer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 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.

[0012] (Basic operation example) First, a basic setting and operation example relating to UCA used in the transmitting device and the receiving device in this embodiment will be described.

[0013] Fig. 1 is a diagram showing an example of phase setting of a UCA for generating an OAM mode signal. The UCA shown in Fig. 1 is a UCA consisting of eight antenna elements.

[0014] In Fig. 1, 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 ●) of the UCA. In other words, a 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). For example, when the UCA is composed of m = 8 antenna elements as shown in Fig. 1 and a signal of OAM mode n = 2 is generated, 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 two times as shown in Fig. 1 (3).

[0015] 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.

[0016] By generating different signal sequences as signals in different OAM modes and transmitting the generated signals simultaneously, wireless communication using spatial multiplexing can be performed. On the transmitting side, signals to be transmitted in each OAM mode may be generated and combined in advance and a combined signal for each OAM mode may be transmitted using a single UCA, or multiple UCAs may be used to transmit signals for each OAM mode using different UCAs for each OAM mode.

[0017] In order to separate the OAM multiplexed signals on the receiving side, the phase of each antenna element of the UCA on the receiving side is set to be opposite to the phase of the antenna elements on the transmitting side.

[0018] However, if interference occurs between OAM modes due to an axial misalignment between the transmitting and receiving antennas, it becomes necessary to separate the signals between the OAM modes mixed due to interference by digital signal processing such as channel equalization processing and successive interference cancellation processing. Note that interference between OAM modes means, for example, that a signal transmitted from a transmitting device in OAM mode 1 is output as an OAM mode 2 signal on the receiving side.

[0019] Figure 2 shows examples of phase distribution and signal intensity distribution of OAM multiplexed signals. In Figures 2(1) and (2), the arrows represent the phase distribution of OAM mode 1 and OAM mode 2 signals as viewed from the transmitting side at an end face (orthogonal propagation plane) perpendicular to the propagation direction. The arrows start at 0 degrees, the phase changes linearly, and the arrows end at 360 degrees. In other words, an OAM mode n signal propagates while its phase rotates n times (n x 360 degrees) on the orthogonal propagation plane. Note that the arrows of the phase distribution of OAM mode -1 and -2 signals point in opposite directions.

[0020] The signal intensity distribution and the position where the signal intensity is maximum differ for each OAM mode. However, the intensity distribution is the same for the same OAM mode with different signs. Specifically, the higher the order of the OAM mode, the farther the position where the signal intensity is maximum is from the propagation axis (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 signals of OAM mode 0, OAM mode 1, and OAM mode 2.

[0021] Figure 2 (3) shows the position where the signal strength is maximum for each OAM mode as a circle. The higher the OAM mode, the farther the position where the signal strength is maximum is from the central axis. Also, the beam diameter of the OAM mode multiplexed signal expands depending on the propagation distance, so the circle showing the position where the signal strength is maximum for each OAM mode becomes larger.

[0022] The system configuration and operation example of this embodiment will be described in detail below.

[0023] (System Configuration) 3 is a configuration diagram of a communication system according to an embodiment of the present invention. As shown in FIG. 3, the wireless communication system according to the embodiment includes a transmitting device 100 and a receiving device 200.

[0024] The transmitting device 100 and the receiving device 200 each include a UCA and a Butler circuit. In transmitting and receiving desired data, the transmitting device 100 multiplexes and transmits signals of one or more OAM modes, and the receiving device 200 receives the signal multiplexed with one or more OAM modes transmitted from the transmitting device 100 and separates the signals of each OAM mode.

[0025] The transmitting device 100 and the receiving device 200 are wireless communication devices that perform wireless communication. In this embodiment, it is assumed that the transmitting device 100 is a stationary base station and the receiving device 200 is a mobile terminal. However, this assumption is only an example. For example, the transmitting device 100 and the receiving device 200 may both be stationary base stations, or the transmitting device 100 and the receiving device 200 may both be mobile terminals. In addition, since multiple wireless communication devices communicate bidirectionally, each wireless communication device may have the functions of the transmitting device 100 and the receiving device 200 described later.

[0026] Next, the power control method of the transmission signal will be described in comparison with the conventional method.

[0027] (Conventional power control method) 4 is a diagram for explaining a power control method according to the conventional technology. Conventionally, it is common to perform line design so that the power of a transmission signal in a transmission device 100 is P1dB (1 dB compression point) or less. However, for a transmission device 100 that transmits a signal in a high frequency band such as Sub-THz, power below P1dB is insufficient, and it is difficult to ensure a reception SNR when the transmission distance is long.

[0028] (Power control method according to the present embodiment) FIG. 5 is a diagram for explaining a power control method according to an embodiment of the present invention. In this embodiment, the region from P1dB to Psat is utilized to ensure a margin in line design. In addition, the transmitting device 100 dynamically determines the degree of power exceeding P1dB, for example, the maximum power value Pth, based on various parameters. Furthermore, in order to deal with the nonlinearity caused by this, the receiving device 200 performs demodulation processing using CLUSTERING such as DBSCAN. As a result, the receiving SNR in the receiving device 200 is increased, and the communication quality in long-distance wireless communication in a high-frequency band can be improved.

[0029] (Example of each device configuration) Next, an example of the device configuration of the transmitting device 100 and the receiving device 200 will be described.

[0030] (Example of transmitter configuration) First, a description will be given of the transmitting device 100. Fig. 6 is a diagram showing an example of the configuration of the transmitting device. As shown in FIG. 6, the transmitting device 100 includes a UCA 110, an OAM mode generating device 120, a signal processing device 130, and a transmission control device 140.

[0031] The signal processing device 130 generates a digital signal to be transmitted on a carrier wave from the input data, converts the digital signal to an analog signal (digital-analog conversion), and converts the frequency of the analog signal to the frequency band of the carrier wave (e.g., sub-THz band). The signal processing device 130 inputs the generated analog signal to the OAM mode generating device 120 (Butler circuit).

[0032] In this embodiment, the transmission control device 140 determines a power control method based on various parameters, and instructs the signal processing device 130 to generate a signal using the determined power control method.

[0033] In addition, when signal processing device 130 receives an instruction from transmission control device 140 to generate OAM mode 1 and OAM mode 2 signals, it generates those signals and inputs the OAM mode 1 signal (signal to be transmitted by OAM mode 1 radio waves) to an input port corresponding to OAM mode 1 of OAM mode generating device 120 (Butler circuit), and inputs the OAM mode 2 signal (signal to be transmitted by OAM mode 2 radio waves) to an input port corresponding to OAM mode 2 of OAM mode generating device 120 (Butler circuit).

[0034] As described above, the OAM mode generating device 120 is a Butler circuit. Fig. 7 is a diagram showing an example of a connection configuration between the Butler circuit and antenna elements in a transmitting device. The UCA 110 in the example shown in Fig. 7 is an antenna in which eight antenna elements #1 to #8 are arranged in a circular shape.

[0035] Also, Fig. 7 shows that the Butler circuit has N input ports. Basically, the number of output ports is the maximum number of N, and in the case of the example of Fig. 6 where there are eight output ports, the maximum number of N is 8. Note that "port" may also be called "terminal".

[0036] 7, the UCA 110 may have one UCA and one Butler circuit, and the number of antenna elements may be eight, but this is merely an example. There may be more than one UCA and more than one Butler circuit. The number of antenna elements in the UCA 110 may be more than eight or less than eight.

[0037] 7 shows, as an example, that a signal to be transmitted in OAM mode 1 is input to input port A, and a signal to be transmitted in OAM mode -1 is input to input port B. Of the N input ports, the input ports other than input port A and input port B support OAM modes other than OAM modes 1 and -1.

[0038] For input from input port A, signals with a phase difference of 45° (360° / 8) are output from each output port in a counterclockwise direction, and for input from input port B, signals with a phase difference of -45° are output from each output port in a counterclockwise direction. In other words, when there is input to both input port A and input port B, a signal in which two signals with different phases are combined (multiplexed) is output from each output port.

[0039] Specifically, in UCA 110, for the sake of convenience, if antenna element #1 is taken as the reference (phase 0°), each antenna element of UCA 110 outputs a signal that is a combination of two signals having the following phases.

[0040] Antenna element #1 = (0°, 0°), antenna element #2 = (45°, -45°), antenna element #3 = (90°, -90°), antenna element #4 = (135°, -135°), antenna element #5 = (180°, -180°), antenna element #6 = (225°, -225°), antenna element #7 = (270°, -270°), antenna element #8 = (315°, -315°).

[0041] In the example of Fig. 7, the output port J of the OAM mode generating device 120 (Butler circuit) is connected to the antenna element #1 of the UCA 110, the output port I is connected to the antenna element #2 of the UCA 110, the output port H is connected to the antenna element #3 of the UCA 110, the output port G is connected to the antenna element #4 of the UCA 110, the output port F is connected to the antenna element #5 of the UCA 110, the output port E is connected to the antenna element #6 of the UCA 110, the output port D is connected to the antenna element #7 of the UCA 110, and the output port C is connected to the antenna element #8 of the UCA 110. For convenience of illustration, only the connection of the output port J is shown in Fig. 7. The signal output from each output port is supplied to the connected antenna element and is output as a radio wave from the antenna element.

[0042] (Example of functional configuration of a transmission control device) 8 is a diagram showing an example of a functional configuration of a transmission control device 140. The transmission control device 140 includes a communication characteristics information acquisition unit 141, a power control method determination unit 142, a signal processing control unit 143, and an OAM mode generation control unit 144.

[0043] The communication characteristic information acquisition unit 141 acquires communication characteristic information by receiving from the receiving device 200 or another device, etc. The communication characteristic information is information indicating characteristics of communication between the transmitting device 100 and the receiving device 200, and is, for example, (1) a transmission / reception distance, (2) a desired number of multi-level modulations, (3) a peak-to-average power ratio (PAPR) of a signal, (4) characteristics of a region from P1dB to Psat in a communication device such as the UCA 110, (5) a signal-noise ratio (SNR) of a received signal, and (6) an error vector magnitude (EVM) of a received signal.

[0044] Among these, the transmission control device 140 may store in advance the setting values ​​and the characteristics of the transmitting device 100, such as (1) the transmission / reception distance, (2) the desired number of multi-level modulations, (3) the peak-to-average power ratio (PAPR) of the signal, and (4) the characteristics of the region from P1dB to Psat in a communication device such as the UCA 110. Also, information related to the receiving device 200, such as (5) the signal-noise ratio (SNR) of the received signal, and (6) the error vector magnitude (EVM) of the received signal, may be received from the receiving device 200.

[0045] The transmission control device 140 may assume that the transmission and reception distance (1) is already known, or may receive information indicating the measurement result from a measuring device (not shown) or the like.

[0046] The power control method determination unit 142 determines the power control method for the transmission signal based on the communication characteristic information. Specific power control methods will be described below in examples 1 to 3.

[0047] <Example 1> The transmission control device 140 stores in advance related information indicating the relationship between the SNR of the received signal and the number of modulation levels. Then, the power control method determination unit 142 (1) calculates propagation attenuation and channel loss based on the transmission and reception distance, and determines based on the above-mentioned related information whether (5) the SNR of the received signal (2) is a value that allows the desired number of modulation levels to be achieved even if the transmission power is set to P1 dB or less.

[0048] Next, if the power control method determination unit 142 determines that the desired modulation number can be achieved, it controls the power of the transmission signal to be equal to or less than P1dB (first threshold value), and if it determines that the desired modulation number cannot be achieved, it controls the power of the transmission signal to be equal to or less than a threshold value Pth. The threshold value (Pth) is a threshold value (third threshold value) that is preset as a value equal to or more than P1dB (first threshold value) and equal to or less than Psat (second threshold value).

[0049] In addition, the power control method determination unit 142 may store in advance information indicating to what extent the nonlinearity of the received signal can be dealt with by clustering such as DBSCAN by the receiving device 200 described later, or may accumulate the information by feeding it back from the receiving device 200, and determine the threshold value Pth based on the information.

[0050] <Example 2> The transmission control device 140 stores in advance information indicating the possibility of performance improvement when controlling the power of a transmission signal to P1 dB or less (conventional method) and when controlling it to P1 dB or more (this embodiment). The power control method determination unit 142 determines the power control method based on the information.

[0051] For example, based on the information, the power control method determination unit 142 determines whether (5) the SNR of the received signal is a value sufficient for transmission of a desired multi-level modulation number (2) when the power is increased by 2 dB from P1 dB. (2) The desired multi-level modulation number is, for example, 16QAM (Quadrature Amplitude Modulation) by Quadrature Phase Shift Keying (QPSK).

[0052] Depending on the result of the judgment, the power control method determination unit 142 determines whether to control the power of the transmission signal so that it is equal to or less than P1dB (first threshold) as in the conventional method, or to control the power of the transmission signal so that it is equal to or less than a threshold Pth (third threshold).

[0053] Also, similarly to example 1, the power control method determination unit 142 may store in advance information indicating to what extent the nonlinearity of the received signal can be accommodated by clustering such as DBSCAN by the receiving device 200 described later, or may accumulate the information by feedback from the receiving device 200, and determine the threshold value Pth based on the information.

[0054] <Example 3> The power control method determination unit 142 may determine the power control method based on (4) characteristics of the region from P1dB to Psat in a communication device such as the UCA 110. Note that the method of acquiring information indicating this characteristic is not limited to the above-mentioned method, and may be acquired by other methods. For example, the power control method determination unit 142 determines the power control method based on the difference between P1dB (first threshold) and Psat (second threshold).

[0055] Specifically, a case will be described where the difference between P1dB (first threshold) and Psat (second threshold) is 10 dB. When performing power control at or below Pth, the power control method determination unit 142 controls so that the proportion of communications 1 dB or more higher than P1dB is 90%, and the proportion of communications 2 dB or more higher is 80%. In this way, the power control method determination unit 142 determines a control method in which the proportion of communications with high power gradually decreases based on the stepwise thresholds. This makes it possible to protect communication devices such as the UCA 110 from excessive power.

[0056] The signal processing control unit 143 controls the signal processing device 130 to generate an analog transmission signal using the determined power control method.

[0057] The OAM mode generation control unit 144 controls the signal processing device 130 and the OAM mode generation device 120 so as to generate signals of each OAM mode based on the generated transmission signal.

[0058] (Operation of transmission control device) Next, a description will be given of the operation of the transmission control device 140. The transmission control device 140 executes a transmission control process in response to a user operation or the like.

[0059] 9 is a flowchart showing an example of the flow of a transmission control process. The communication characteristic information acquisition unit 141 acquires communication characteristic information (step S11). Next, the power control method determination unit 142 determines a power control method for a transmission signal using any one of the methods of the above-mentioned examples 1 to 3, or a combination of the methods, based on the communication characteristic information (step S12).

[0060] Next, the signal processing control unit 143 controls the generation of a transmission signal (step S13), and the OAM mode generation control unit 144 controls the generation of a signal in each OAM mode (step S14).

[0061] (Example of receiving device configuration) Next, a description will be given of the receiving device 200. Fig. 10 is a diagram showing an example of the configuration of the receiving device. As shown in Fig. 10, the receiving device 200 includes a UCA 210, an OAM mode separation device 220, a signal processing device 230, and a reception control device 240.

[0062] The OAM mode demultiplexing device 220 includes a Butler circuit. The OAM mode demultiplexing device 220 also includes a measurement unit 221 that measures the SNR, error vector magnitude, and the like output from each output port of the Butler circuit.

[0063] Fig. 11 is a diagram showing an example of a connection configuration between a Butler circuit and antenna elements in a receiving device. The UCA 210 in the example shown in Fig. 11 is an antenna in which eight antenna elements #1 to #8 are arranged in a circular shape.

[0064] 11 corresponds to the Butler circuit in the transmitting device 100 with the input and output reversed.

[0065] As shown in Fig. 11, the Butler circuit has N output ports. As shown in Fig. 10, the configuration having one UCA and one Butler circuit, and the number of antenna elements being eight, are just examples. There may be multiple UCAs and multiple Butler circuits. The number of antenna elements of the UCA 210 may be more or less than eight.

[0066] 11 shows, as an example, that a signal in OAM mode 1 is output from output port A, and a signal in OAM mode -1 is output from output port B. Of the N output ports, the output ports other than output port A and output port B support OAM modes other than OAM modes 1 and -1.

[0067] Each antenna element of the UCA 210 and each input port of the OAM mode separation device 220 (Butler circuit) are connected as shown in the figure (for convenience of illustration, only #7 is shown with a connection line). In the Butler circuit, phase conversion and the like is performed in the opposite direction to that of the Butler circuit on the transmitting side, and from each output port, a signal in the OAM mode corresponding to that output port is output.

[0068] The signal processing device 230 shown in Fig. 10 converts the analog signal received from the OAM mode demultiplexing device 220 (Butler circuit) into a digital signal (analog-digital conversion), demodulates it, and generates and outputs data (bit string). The signal processing device 230 also performs signal separation processing by digital signal processing. Note that if signal separation is not necessary, the signal separation processing does not have to be performed.

[0069] The reception control device 240 instructs the signal processing device 230 to receive from the corresponding output port of the OAM mode demultiplexing device 220 (Butler circuit). The signal processing device 230 performs demodulation processing and the like using the signal received from the corresponding output port.

[0070] (Example of functional configuration of a reception control device) 12 is a diagram showing an example of the functional configuration of the reception control device 240. The reception control device 240 includes an OAM mode separation control unit 241, a signal processing control unit 242, a measurement information acquisition unit 243, and a measurement information transmission unit 244.

[0071] OAM mode separation control section 241 instructs OAM mode separation device 220 to separate the received signal into each OAM mode.

[0072] The signal processing control unit 242 instructs the signal processing device 230 to demodulate the separated signals of each OAM mode. Specifically, the signal processing control unit 242 controls the demodulation of the signal having nonlinearity by clustering using a method such as DBSCAN or "k-means clustering". This makes it possible to avoid a decrease in the accuracy of the demodulation process even if nonlinearity occurs in the output level of a signal with power exceeding P1db.

[0073] In other words, conventional demodulation methods make decisions based on predetermined decision points, and so although they can distinguish between blocks of demodulated signals due to nonlinear effects, if the blocks deviate from the predetermined decision points, they are judged as not communicating, i.e., as a transmission / reception error. On the other hand, clustering judges each block separately, so demodulation can be performed without errors even in such cases.

[0074] Fig. 13 is a diagram for explaining a conventional demodulation method for a nonlinear signal. For example, the portion indicated by a circle 902 in Fig. 13 is outside the dotted line 901 indicating the range for judgment, and therefore would result in an error in the conventional method, but by using clustering or the like, demodulation processing can be performed without errors.

[0075] In other words, clustering is a data analysis method that classifies a large number of data groups into groups with similar characteristics. For example, in the case of 16QAM, by classifying the data into 16 groups, it becomes possible to demodulate signals with output levels outside the specified range.

[0076] The measurement information acquisition unit 243 acquires measurement information indicating the SNR, error vector amplitude, etc. measured by the measurement unit 221. The measurement information transmission unit 244 transmits the acquired measurement information to the transmission device 100. The transmitted measurement information functions as a part or all of the communication characteristic information.

[0077] (Operation of the receiving control device) Next, a description will be given of the operation of the reception control device 240. In response to receiving a signal from the transmission device 100, the reception control device 240 executes reception control processing.

[0078] 14 is a flowchart showing an example of the flow of reception control processing. The OAM mode separation control unit 241 controls separation of the received signal into each OAM mode (step S21). Next, the signal processing control unit 242 controls demodulation of the signal of each OAM mode (step S22). Next, the measurement information acquisition unit 243 acquires measurement information (step S23). Then, the measurement information transmission unit 244 transmits the measurement information to the transmission device 100 (step S24).

[0079] Next, the demodulation method in step S22 of the reception control process will be described in comparison with the conventional method.

[0080] 15 is a diagram for explaining a conventional method for demodulating a received signal. In the case of 16QAM, for example, the conventional demodulation method is a method in which the amplitude of an in-phase carrier wave (in-phase) and the amplitude of a quadrature carrier wave (quadrature) are each divided into four ranges as shown by the dotted line 901, and demodulated for each range.

[0081] 16 is a diagram for explaining a method for demodulating a received signal according to an embodiment of the present invention. In this embodiment, if nonlinearity occurs in a signal with power exceeding P1db, there is a possibility that the signal will not fall within a specified amplitude range as shown by dotted line 901. Therefore, the signal processing control unit 242 realizes demodulation of a signal that may have nonlinearity by classifying the signal into data groups with a specified number of modulations by clustering.

[0082] According to the transmitting device 100 of this embodiment, it is determined whether or not to transmit a signal with a power of P1 dB or more based on communication characteristic information. This ensures a margin in line design. Also, the transmitting device 100 dynamically determines the degree of power exceeding P1 dB, for example, the maximum power Pth, based on various parameters. Also, in order to deal with the nonlinearity caused by this, the receiving device 200 performs demodulation processing using clustering by a method such as DBSCAN or "k-means clustering". As a result, it is possible to improve communication quality in long-distance wireless communication in a high-frequency band.

[0083] The transmission control device 140 and the reception control device 240 according to this embodiment can be realized, for example, by making a computer execute a program in which the processing contents described in this embodiment are described. Note that this "computer" may be a physical machine or a virtual machine on the cloud. When a virtual machine is used, the "hardware" described here is virtual hardware.

[0084] The above program can be recorded on a computer-readable recording medium (such as a portable memory) and stored or distributed. The above program can also be provided via a network such as the Internet or email.

[0085] 17 is a diagram showing an example of the hardware configuration of the computer. The computer in FIG. 17 includes a processor 1001, a memory 1002, a communication device 1003, and the like, which are interconnected via a bus B.

[0086] A program for implementing processing in the computer is stored, for example, in memory 1002. Processor 1001 implements functions related to the device in accordance with the program stored in memory 1002. Communication device 1003 transmits and receives information to and from other devices.

[0087] (Summary of the embodiment) This specification describes at least the transmission control device, the wireless communication system, the transmission control method, and the program described in the following sections. (Section 1) a communication characteristic information acquisition unit for acquiring communication characteristic information indicating a characteristic of communication; a power control method determination unit that determines a power control method for a transmission signal with power up to a third threshold value that is a threshold value between a first threshold value and a second threshold value that are predefined based on the communication characteristic information; and a signal processing control unit that generates a transmission signal using the determined power control method. Transmission control device. (Section 2) The communication characteristic information includes any one of a transmission / reception distance, a desired number of multi-level modulations, a peak-to-average power ratio of a signal, a characteristic of a region from the first threshold to the second threshold in a communication device, an SNR of a received signal, and an error vector amplitude of the received signal. 2. A transmission control device as described in claim 1. (Section 3) The power control method determination unit determines, based on the transmission / reception distance, whether the SNR will be a value that allows the desired multi-level modulation number to be achieved even if the transmission power is set to the first threshold or less, based on related information indicating a relationship between the SNR of the received signal and the multi-level modulation number, and if it determines that the SNR will be a value that allows the desired multi-level modulation number to be achieved, controls the power of the transmission signal to be equal to or less than the first threshold, and if it determines that the SNR will not be a value that allows the desired multi-level modulation number to be achieved, controls the power of the transmission signal to be equal to or less than the third threshold. 3. A transmission control device as set forth in claim 2. (Section 4) the power control method determination unit determines a power control method based on characteristics of a region from the first threshold to the second threshold in the communication device. 3. A transmission control device as set forth in claim 2. (Section 5) the power control method determination unit determines a control method in which a ratio of high power communications is gradually reduced based on a stepwise threshold value; A transmission control device as set forth in claim 4. (Section 6) A wireless communication system including a transmission control device and a reception control device, The transmission control device includes: a communication characteristic information acquisition unit for acquiring communication characteristic information indicating a characteristic of communication; a power control method determination unit that determines a power control method for a transmission signal with power up to a third threshold value that is a threshold value between a first threshold value and a second threshold value that are predefined based on the communication characteristic information; a signal processing control unit that generates a transmission signal using the determined power control method; The reception control device includes: A signal processing control unit demodulates a received signal by classifying the received signal into a data group of a prescribed number of modulations by clustering. Wireless communication system. (Section 7) A computer-implemented transmission control method, comprising: acquiring communication characteristic information indicating a characteristic of the communication; determining a power control method for a transmission signal with power up to a third threshold value, which is a threshold value between a first threshold value and a second threshold value, based on the communication characteristic information; and generating a transmission signal using the determined power control method. Transmission control method. (Section 8) A program for causing a computer to function as each unit in the transmission control device according to any one of claims 1 to 5.

[0088] 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]

[0089] 100 Transmitting device 110 UCA 120 OAM mode generator 130 Signal Processing Device 140 Transmission control device 141 Communication characteristic information acquisition unit 142 Power control method determination unit 143 Signal processing control section 144 OAM mode generation control unit 200 Receiving device 210 UCA 220 OAM mode separator 221 Measuring section 230 Signal Processing Device 240 Receiving control device 241 OAM mode separation control section 242 Signal Processing Control Unit 243 Measurement information acquisition section 244 Measurement information transmission unit 1001 Processor 1002 Memory 1003 Communication equipment

Claims

1. a communication characteristic information acquisition unit for acquiring communication characteristic information indicating a characteristic of communication; a power control method determination unit that determines a power control method for a transmission signal with power up to a third threshold value that is a threshold value between a first threshold value and a second threshold value that are predefined based on the communication characteristic information; a signal processing control unit that generates a transmission signal using the determined power control method; the communication characteristic information includes any one of a transmission / reception distance, a desired number of multi-level modulations, a peak-to-average power ratio of a signal, a characteristic of a region from the first threshold to the second threshold in a communication device, an SNR of a received signal, and an error vector amplitude of the received signal; The power control method determination unit determines, based on the transmission / reception distance, whether the SNR will be a value that allows the desired multi-level modulation number to be achieved even if the transmission power is set to the first threshold or less, based on related information indicating a relationship between the SNR of the received signal and the multi-level modulation number, and if it is determined that the SNR will be a value that allows the desired multi-level modulation number to be achieved, controls the power of the transmission signal to be equal to or less than the first threshold, and if it is determined that the SNR will not be a value that allows the desired multi-level modulation number to be achieved, controls the power of the transmission signal to be equal to or less than the third threshold. Transmission control device.

2. A wireless communication system including a transmission control device and a reception control device, The transmission control device includes: a communication characteristic information acquisition unit for acquiring communication characteristic information indicating a characteristic of communication; a power control method determination unit that determines a power control method for a transmission signal with power up to a third threshold value that is a threshold value between a first threshold value and a second threshold value that are predefined based on the communication characteristic information; a signal processing control unit that generates a transmission signal using the determined power control method; The reception control device includes: A signal processing control unit demodulates a received signal by classifying the received signal into a data group of a prescribed number of modulations by clustering; the communication characteristic information includes any one of a transmission / reception distance, a desired number of multi-level modulations, a peak-to-average power ratio of a signal, a characteristic of a region from the first threshold to the second threshold in a communication device, an SNR of a received signal, and an error vector amplitude of the received signal; The power control method determination unit determines, based on the transmission / reception distance, whether the SNR will be a value that allows the desired multi-level modulation number to be achieved even if the transmission power is set to the first threshold or less, based on related information indicating a relationship between the SNR of the received signal and the multi-level modulation number, and if it is determined that the SNR will be a value that allows the desired multi-level modulation number to be achieved, controls the power of the transmission signal to be equal to or less than the first threshold, and if it is determined that the SNR will not be a value that allows the desired multi-level modulation number to be achieved, controls the power of the transmission signal to be equal to or less than the third threshold. Wireless communication system.

3. A computer-implemented transmission control method, comprising: The computer, acquiring communication characteristic information indicating a characteristic of the communication; a power control method determination step of determining a power control method for a transmission signal with power up to a third threshold value, which is a threshold value between a first threshold value and a second threshold value, based on the communication characteristic information; generating a transmission signal using the determined power control method; Run the communication characteristic information includes any one of a transmission / reception distance, a desired number of multi-level modulations, a peak-to-average power ratio of a signal, a characteristic of a region from the first threshold to the second threshold in a communication device, an SNR of a received signal, and an error vector amplitude of the received signal; The power control method determination step determines, based on the transmission / reception distance, whether the SNR will be a value that allows the desired number of modulation levels to be achieved even if the transmission power is set to the first threshold or less, based on related information indicating a relationship between the SNR of the received signal and the number of modulation levels. If it is determined that the SNR will be a value that allows the desired number of modulation levels to be achieved, the power of the transmission signal is controlled to be equal to or less than the first threshold, and if it is determined that the SNR will not be a value that allows the desired number of modulation levels to be achieved, the power of the transmission signal is controlled to be equal to or less than the third threshold. Transmission control method.

4. A program for causing a computer to function as each unit in the transmission control device according to claim 1.

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