Ground system, unmanned aerial vehicle, and wireless relay system

Abstract

To provide a ground system, an unmanned aircraft, and a radio relay system capable of appropriately replacing the unmanned aircraft under the assumption that the radio relay system is mounted on the unmanned aircraft.SOLUTION: The ground system includes a transmission unit configured to transmit, to an unmanned aerial vehicle, a frame to be relayed by the unmanned aerial vehicle, a reception unit configured to receive, from the unmanned aerial vehicle, a signal indicating that synchronization of the frame is established in the unmanned aerial vehicle, and a control unit configured to control transmission of switching information for notifying a timing for starting or stopping relay of the frame in the unmanned aerial vehicle in accordance with the signal indicating that synchronization of the frame is established.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to ground systems, unmanned aerial vehicles, and radio relay systems. [Background technology]

[0002] In recent years, wireless repeaters have been used to expand the coverage area of ​​wireless systems. Known wireless repeater systems include a system in which mutually orthogonal resources are not allocated to each wireless repeater (e.g., Patent Document 1), and a system in which mutually orthogonal resources are allocated to each wireless repeater (e.g., Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-98156 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-139157 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, by mounting a wireless repeater on an unmanned aerial vehicle, it is conceivable that in the event of a disaster or the like, a temporary line may be set up using the wireless repeater mounted on the unmanned aerial vehicle.

[0005] In the case described above, since unmanned aircraft are battery-powered, there is a limit to the flight time of the unmanned aircraft, and it becomes necessary to replace unmanned aircraft equipped with wireless repeaters.

[0006] Therefore, the present disclosure has been made to solve the above-mentioned problems, and aims to provide a ground system, an unmanned aircraft, and a wireless relay system that enable appropriate replacement of unmanned aircraft when assumed to be installed on the unmanned aircraft. [Means for solving the problem]

[0007] The disclosed aspect is a ground system comprising: a transmitting unit that transmits to an unmanned aerial vehicle a frame to be relayed by the unmanned aerial vehicle; a receiving unit that receives from the unmanned aerial vehicle a signal indicating that synchronization of the frame has been established in the unmanned aerial vehicle; and a control unit that controls the transmission of switching information that notifies the unmanned aerial vehicle of the timing to start or stop relaying the frame in response to the signal indicating that synchronization of the frame has been established.

[0008] An aspect of the disclosure is an unmanned aerial vehicle comprising: a repeater that receives frames to be relayed by the unmanned aerial vehicle from a ground system and relays the frames received from the ground system; a transmitter that transmits a signal to the ground system indicating that synchronization of the frames has been established in the unmanned aerial vehicle; and a control unit that controls the start or stop of relaying the frames based on switching information that notifies the unmanned aerial vehicle of the timing to start or stop relaying the frames, wherein the switching information is transmitted in response to the signal indicating that synchronization of the frames has been established.

[0009] An aspect of the disclosure is a wireless relay system comprising an unmanned aerial vehicle and a ground system that transmits frames to be relayed by the unmanned aerial vehicle, wherein the unmanned aerial vehicle transmits a signal to the ground system indicating that synchronization of the frames has been established in the unmanned aerial vehicle, the ground system transmits switching information in response to the signal indicating that synchronization of the frames has been established, notifying the unmanned aerial vehicle of the timing to start or stop relaying the frames, and the unmanned aerial vehicle controls the start or stop of relaying the frames based on the switching information. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a ground system, an unmanned aerial vehicle, and a wireless relay system that enable appropriate replacement of unmanned aerial vehicles when assumed to be mounted on the unmanned aerial vehicle. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a wireless relay system 10 according to an embodiment. [Figure 2] FIG. 2 is a diagram for explaining a usage scene according to the embodiment. [Figure 3] FIG. 3 is a diagram showing a ground system 100 and an unmanned aerial vehicle 300 according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating a wireless relay method according to the embodiment. [Figure 5] FIG. 5 is a diagram illustrating a wireless relay method according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, an embodiment of the present invention will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and the ratios of the dimensions may differ from those of the actual parts.

[0013] Therefore, specific dimensions should be determined with reference to the following explanation. Of course, the dimensional relationships and ratios may differ between the drawings.

[0014] [Disclosure Summary] The ground system according to the disclosure summary includes a transmitting unit that transmits to the unmanned aerial vehicle a frame to be relayed by the unmanned aerial vehicle, a receiving unit that receives a signal from the unmanned aerial vehicle indicating that synchronization of the frame has been established in the unmanned aerial vehicle, and a control unit that controls the transmission of switching information that notifies the unmanned aerial vehicle of the timing to start or stop relaying the frame in response to the signal indicating that synchronization of the frame has been established.

[0015] The unmanned aerial vehicle according to the disclosure summary comprises a repeater that receives frames to be relayed by the unmanned aerial vehicle from a ground system and relays the frames received from the ground system, a transmitter that transmits a signal to the ground system indicating that synchronization of the frames has been established in the unmanned aerial vehicle, and a control unit that controls the start or stop of relaying the frames based on switching information that notifies the unmanned aerial vehicle of the timing to start or stop relaying the frames, and the switching information is transmitted in response to the signal indicating that synchronization of the frames has been established.

[0016] The wireless relay system according to the disclosure summary comprises an unmanned aerial vehicle and a ground system that transmits frames to be relayed by the unmanned aerial vehicle, wherein the unmanned aerial vehicle transmits a signal to the ground system indicating that synchronization of the frames has been established in the unmanned aerial vehicle, and the ground system transmits switching information in response to the signal indicating that synchronization of the frames has been established, notifying the unmanned aerial vehicle of the timing to start or stop relaying the frames, and the unmanned aerial vehicle controls the start or stop of relaying the frames based on the switching information.

[0017] In the outline of the disclosure, the ground system transmits switching information in response to a signal indicating that frame synchronization has been established, notifying the unmanned aerial vehicle of the timing to start or stop relaying the frame, and the unmanned aerial vehicle controls the start or stop of frame relay based on the switching information. With this configuration, the unmanned aerial vehicle can be appropriately replaced based on the switching information transmitted in response to the signal indicating that frame synchronization has been established.

[0018] [Embodiment] (Radio relay system) A wireless relay system according to an embodiment will be described below. Fig. 1 is a diagram showing a wireless relay system 10 according to an embodiment. As shown in Fig. 1, the wireless relay system 10 includes a first device 100, a second device 200, and an unmanned aerial vehicle 300.

[0019] The wireless relay system 10 may employ FDD (Frequency Division Duplex) or TDD (Time Division Duplex).

[0020] Here, in the communication in the wireless relay system 10, scattered pilot signals may be arranged across two or more frames. The scattered pilot signals are signals used for demodulation of OFDM (Orthogonal Frequency Division Multiplexing). In the communication in the wireless relay system 10, signals may be transmitted continuously across two or more frames.

[0021] First device 100 communicates with second device 200 via a repeater (repeater 310, described later) mounted on unmanned aerial vehicle 300. First device 100 may be a base station, a broadcasting station, or a field pickup unit (FPU).

[0022] When a signal is transmitted from first device 100 to second device 200, first device 100 is an example of a transmitting device. When a signal is transmitted from second device 200 to first device 100, first device 100 is an example of a receiving device.

[0023] Second device 200 communicates with first device 100 via a repeater (repeater 310, described later) mounted on unmanned aerial vehicle 300. Second device 200 may be a mobile station, a receiver, or an FPU.

[0024] When a signal is transmitted from first device 100 to second device 200, second device 200 is an example of a receiving device. When a signal is transmitted from second device 200 to first device 100, second device 200 is an example of a transmitting device.

[0025] The unmanned aerial vehicle 300 is an aircraft equipped with a repeater (repeater 310, described later). The unmanned aerial vehicle 300 is powered by a battery. The repeater equipped in the unmanned aerial vehicle 300 may relay a signal from the first device 100 to the second device 200. The repeater equipped in the unmanned aerial vehicle 300 may relay a signal from the second device 200 to the first device 100. The unmanned aerial vehicle 300 may be referred to as a UAV (Unmanned Aerial Vehicle) or a drone.

[0026] Although not particularly limited, a signal from first device 100 to second device 200 may be referred to as a DL (Downlink) signal. A signal from second device 200 to first device 100 may be referred to as a UL (Uplink) signal.

[0027] (Usage scenario) A usage scene according to the embodiment will be described below. Fig. 2 is a diagram for explaining a usage scene according to the embodiment. In Fig. 2, unmanned aerial vehicle 300A and unmanned aerial vehicle 300B are examples of unmanned aerial vehicle 300 described above.

[0028] As shown in Fig. 2, in a usage scenario, when unmanned aerial vehicle 300A is performing a relay at a predetermined position, a case is assumed in which the flight time of unmanned aerial vehicle 300A falls below a threshold. In such a case, unmanned aerial vehicle 300B, which has sufficient flight time, is flown to the predetermined position, and unmanned aerial vehicle 300A is replaced with unmanned aerial vehicle 300B. After being replaced with unmanned aerial vehicle 300B, unmanned aerial vehicle 300A returns to the ground.

[0029] In an embodiment, unmanned aerial vehicle 300 (unmanned aerial vehicle 300A and unmanned aerial vehicle 300B) transmits a signal to the ground system indicating that frame synchronization has been established. In response to the signal indicating that frame synchronization has been established, the ground system transmits switching information notifying unmanned aerial vehicle 300 (unmanned aerial vehicle 300A and unmanned aerial vehicle 300B) of the timing to start or stop relaying frames. Unmanned aerial vehicle 300 (unmanned aerial vehicle 300A and unmanned aerial vehicle 300B) controls the start or stop of frame relay based on the switching information.

[0030] For example, when unmanned aerial vehicle 300A is replaced with unmanned aerial vehicle 300B, upon receiving a signal from unmanned aerial vehicle 300B indicating that frame synchronization has been established, the ground system transmits switching information to unmanned aerial vehicle 300A and unmanned aerial vehicle 300B. Unmanned aerial vehicle 300A stops relaying frames based on the switching information, and unmanned aerial vehicle 300B starts relaying frames based on the switching information.

[0031] (Ground Systems and Unmanned Aerial Vehicles) A ground system and an unmanned aerial vehicle according to an embodiment will be described below. A case in which the first device 100 is a transmitting device will be exemplified below. In such a case, the first device 100 is an example of a ground system. Therefore, the first device 100 may be referred to as a ground system 100.

[0032] Fig. 3 is a diagram showing ground system 100 and unmanned aerial vehicle 300 according to an embodiment. Fig. 3 illustrates a case in which unmanned aerial vehicle 300A is replaced with unmanned aerial vehicle 300B. Because unmanned aerial vehicle 300A and unmanned aerial vehicle 300B have the same configuration, unmanned aerial vehicle 300A and unmanned aerial vehicle 300B may be simply referred to as unmanned aerial vehicle 300.

[0033] As shown in FIG. 3, the ground system 100 includes a high frequency unit 110, a receiving unit 120, and a control unit .

[0034] The radio frequency unit 110 converts the frame into a radio frequency signal. The frame may be an FDD frame or a TDD frame. The frame may also be referred to as an OFDM frame. As described above, a scattered pilot signal may be arranged across two or more frames. A signal may also be transmitted continuously across two or more frames.

[0035] In the embodiment, high frequency unit 110 constitutes a transmitting unit that transmits frames to repeater 310 mounted on unmanned aerial vehicle 300 to be relayed by repeater 310 .

[0036] The receiver 120 receives a signal from the unmanned aerial vehicle 300. The receiver 120 may receive the signal via a communication network. The communication network may include, but is not limited to, the Internet or a mobile communication network. The signal may be referred to as a telemetry signal.

[0037] In an embodiment, receiver 120 constitutes a receiver that receives a signal from unmanned aerial vehicle 300 indicating that frame synchronization has been established in unmanned aerial vehicle 300. Hereinafter, the signal indicating that frame synchronization has been established may be referred to as a synchronization status signal.

[0038] The control unit 130 controls each component provided in the ground system 100 and controls the operation of the ground system 100 .

[0039] In an embodiment, the control unit 130 constitutes a control unit that controls the transmission of switching information that notifies the timing to start or stop relaying frames in the unmanned aerial vehicle 300 in response to a signal (synchronization status signal) indicating that frame synchronization has been established.

[0040] Here, the switching information is part of the transmission parameters of the frame. The transmission parameters of the frame may be referred to as TMCC (Transmission and Multiplexing Configuration Control) information or a TMCC signal. The TMCC signal may be inserted into part of the frame.

[0041] Possible values ​​of the switching information may include a value that instructs the start or stop of relaying a frame and a value that does not instruct the start or stop of relaying a frame. For example, the switching information may have a bit length of 1 bit, and "1" may be a value that instructs the start or stop of relaying a frame, and "0" may be a value that does not instruct the start or stop of relaying a frame.

[0042] Control unit 130 may set the switching information to "1" when the number of unmanned aerial vehicles 300 with which frame synchronization is established increases (for example, when it changes from 0 to 1 or from 1 to 2). On the other hand, control unit 130 may set the switching information to "0" when the number of unmanned aerial vehicles 300 with which frame synchronization is established decreases (for example, when it changes from 1 to 0, from 2 to 1, or from 2 to 0) when the number of unmanned aerial vehicles 300 with which frame synchronization is established does not change. In other words, control unit 130 may set the switching information to "1" in a pulsed manner only once each time it receives a synchronization status signal.

[0043] Although not particularly limited, it is possible that switching information set to "1" is called switching information, and switching information set to "0" is not called switching information.

[0044] As shown in Figure 3, unmanned aerial vehicle 300 has a repeater 310 (repeater 310A or repeater 310B), a transmitting unit 320 (transmitting unit 320A or transmitting unit 320B), and a control unit 330 (control unit 330A or control unit 330B).

[0045] The repeater 310 repeats a frame received from the ground system 100. For example, the repeater 310 repeats a frame received from the first device 100 to the second device 200.

[0046] In an embodiment, repeater 310 constitutes a repeater that receives frames from ground system 100 to be relayed by unmanned aerial vehicle 300 and relays frames received from ground system 100 .

[0047] The transmitter 320 transmits the signal to the ground system 100. The transmitter 320 may transmit the signal via a communication network. The communication network may include, but is not limited to, the Internet or a mobile communication network. The signal may be referred to as a telemetry signal.

[0048] In the embodiment, the transmitter 320 constitutes a transmitter that transmits a signal (synchronization status signal) to the ground system 100 indicating that frame synchronization has been established in the unmanned aerial vehicle 300.

[0049] The control unit 330 controls each component provided in the unmanned aerial vehicle 300 and controls the operation of the unmanned aerial vehicle 300.

[0050] The control unit 330 monitors the frames received from the ground system 100 and determines whether or not frame synchronization has been established. When frame synchronization has been established, the control unit 330 instructs the transmission unit 320 to transmit a switching signal.

[0051] In the embodiment, the control unit 330 constitutes a control unit that controls the start or stop of relaying frames based on switching information that notifies the timing of starting or stopping relaying frames in the unmanned aerial vehicle 300.

[0052] When control unit 330 is not currently relaying a frame, it controls repeater 310 to start relaying the frame in accordance with the switching information. That is, control unit 330 instructs repeater 310 to start relaying the frame in accordance with the switching information. For example, when control unit 330 is provided in unmanned aerial vehicle 300B, control unit 330 controls repeater 310 to start relaying the frame in accordance with the switching information.

[0053] Here, the control unit 330 may instruct the repeater 310 to start relaying the frame from the symbol next to the switching information. However, the control unit 330 may also instruct the repeater 310 to start relaying the frame from the guard interval next to the switching information.

[0054] When relaying a frame, control unit 330 performs control to stop relaying the frame in accordance with the switching information. That is, control unit 330 instructs repeater 310 to stop relaying the frame in accordance with the switching information. For example, when control unit 330 is provided in unmanned aerial vehicle 300A, control unit 330 performs control to stop relaying the frame in accordance with the switching information.

[0055] Here, the control unit 330 may instruct the repeater 310 to stop relaying frames from the guard interval following the switching information.

[0056] (Radio relay method) The wireless relay method according to the embodiment will be described below. Fig. 4 is a diagram showing the operation of unmanned aerial vehicle 300 according to the embodiment, and Fig. 5 is a diagram showing the operation of ground system 100 according to the embodiment.

[0057] First, the operation of unmanned aerial vehicle 300 will be described with reference to FIG.

[0058] As shown in FIG. 4, in step S10, unmanned aerial vehicle 300 establishes frame synchronization.

[0059] In step S11, unmanned aerial vehicle 300 transmits to ground system 100 a signal indicating that frame synchronization has been established (synchronization status signal).

[0060] In step S12, unmanned aerial vehicle 300 determines whether or not switching information set to "1" has been received from ground system 100. If unmanned aerial vehicle 300 has received switching information set to "1", it executes the operation of step S13. If unmanned aerial vehicle 300 has not received switching information set to "1", it waits until it receives switching information.

[0061] In step S13, unmanned aerial vehicle 300 starts relaying the frame (emitting radio waves). For example, unmanned aerial vehicle 300 may start relaying the frame from the symbol next to the switching information. However, unmanned aerial vehicle 300 may also start relaying the frame from the guard interval next to the switching information.

[0062] In step S14, unmanned aerial vehicle 300 determines whether or not switching information set to "1" has been received from ground system 100. If unmanned aerial vehicle 300 has received switching information set to "1", it executes the operation of step S15. If unmanned aerial vehicle 300 has not received switching information set to "1", it waits until it receives switching information.

[0063] 4, after starting to emit radio waves, unmanned aerial vehicle 300 may stop emitting radio waves if it stops receiving frames from ground system 100. For example, unmanned aerial vehicle 300 may stop emitting radio waves if it does not receive the (n+1)th frame for a certain period of time after receiving the nth frame.

[0064] In step S15, unmanned aerial vehicle 300 stops relaying frames (emitting radio waves). For example, unmanned aerial vehicle 300 stops relaying frames from the guard interval following the switching information.

[0065] Second, the operation of ground system 100 will be described with reference to Fig. 5. In the initial state of the flow shown in Fig. 5, the number of unmanned aerial vehicles 300 with which frame synchronization is established is zero.

[0066] 5, in step S20, the ground system 100 monitors the synchronization status signal transmitted from the unmanned aerial vehicle 300 to determine whether the number of unmanned aerial vehicles 300 with which frame synchronization is established has changed from 0 to 1. If the number of unmanned aerial vehicles 300 has changed from 0 to 1, the ground system 100 executes the processing of step S21. If the number of unmanned aerial vehicles 300 remains 0, the ground system 100 waits until it receives the synchronization status signal.

[0067] In step S21, the ground system 100 sets the switching information to “1.” For example, the switching information is inserted into a frame and transmitted to the unmanned aerial vehicle 300 as TMCC information.

[0068] In step S22, the ground system 100 monitors the synchronization status signal transmitted from the unmanned aerial vehicle 300 to determine whether the number of unmanned aerial vehicles 300 with which frame synchronization is established has changed from 1 to 2. If the number of unmanned aerial vehicles 300 has changed from 1 to 2, the ground system 100 executes the processing of step S23. If the number of unmanned aerial vehicles 300 remains at 1, the ground system 100 waits until it receives a synchronization status signal.

[0069] In step S23, the ground system 100 sets the switching information to “1.” For example, the switching information is inserted into a frame and transmitted to the unmanned aerial vehicle 300 as TMCC information.

[0070] In step S24, the ground system 100 monitors the synchronization status signal transmitted from the unmanned aerial vehicle 300 to determine whether the number of unmanned aerial vehicles 300 with which frame synchronization is established has changed from 2 to 1. If the number of unmanned aerial vehicles 300 has changed from 2 to 1, the ground system 100 executes the processing of step S25. If the number of unmanned aerial vehicles 300 remains at 2, the ground system 100 waits until it receives a synchronization status signal.

[0071] In step S25, the ground system 100 monitors the synchronization status signal transmitted from the unmanned aerial vehicle 300 to determine whether the number of unmanned aerial vehicles 300 with which frame synchronization is established has changed from 1 to 0. If the number of unmanned aerial vehicles 300 has changed from 1 to 0, the ground system 100 ends the series of processes. If the number of unmanned aerial vehicles 300 remains at 1, the ground system 100 returns to the processing of step S22.

[0072] In FIG. 5, ground system 100 may identify the number of unmanned aerial vehicles 300 with which to establish frame synchronization according to the following options.

[0073] In option 1, the synchronization status signal may be a signal that simply indicates that frame synchronization has been established. In such a case, unmanned aerial vehicle 300 may be configured to periodically transmit the synchronization status signal. If ground system 100 does not receive a synchronization status signal from a given unmanned aerial vehicle 300 before the time elapsed since receiving the most recent synchronization status signal from that unmanned aerial vehicle 300 exceeds a threshold, ground system 100 may detect that frame synchronization has not been established for that unmanned aerial vehicle 300 and determine that the number of unmanned aerial vehicles 300 that have established synchronization has decreased.

[0074] In option 2, the synchronization status signal may be a signal that can indicate that frame synchronization is not established, in addition to that that frame synchronization is established. When ground system 100 receives a synchronization status signal indicating that frame synchronization is not established from a certain unmanned aerial vehicle 300, ground system 100 may detect that frame synchronization is not established for that certain unmanned aerial vehicle 300 and determine that the number of unmanned aerial vehicles 300 that have established synchronization has decreased.

[0075] Although not specifically mentioned in Figure 5, the series of processes may be terminated if it is detected in step S22 that frame synchronization has not been established in one unmanned aerial vehicle 300, i.e., if the number of unmanned aerial vehicles 300 with which frame synchronization has been established changes from 1 to 0. Also, if it is detected in step S24 that frame synchronization has not been established in two unmanned aerial vehicles 300 simultaneously, i.e., if the number of unmanned aerial vehicles 300 with which frame synchronization has been established changes from 2 to 0, the series of processes may be terminated.

[0076] (Action and effect) In the embodiment, ground system 100 transmits switching information notifying unmanned aerial vehicle 300 of the timing to start or stop relaying frames in response to a signal (synchronization status signal) indicating that frame synchronization has been established, and unmanned aerial vehicle 300 controls the start or stop of frame relay based on the switching information. With this configuration, unmanned aerial vehicle 300 can be appropriately switched based on the switching information transmitted in response to the synchronization status signal.

[0077] In an embodiment, the switching information may be part of the transmission parameters (TMCC information) of the frame. With this configuration, it is possible to simultaneously instruct two unmanned aerial vehicles 300 of the switching timing using a simple configuration (i.e., information that unmanned aerial vehicles 300 always receive).

[0078] Furthermore, since switching information is inserted into the frame that is ultimately relayed to the receiving device (e.g., the second device 200), the receiving device can also understand the timing of switching the unmanned aerial vehicle 300, so the receiving device can properly receive the frame even in cases where a scattered pilot signal is placed across two or more frames or where a signal is transmitted continuously across two or more frames.

[0079] In an embodiment, possible values ​​of the switching information may include a value that instructs the start or stop of relaying a frame and a value that does not instruct the start or stop of relaying a frame. With this configuration, it is possible to simultaneously instruct two unmanned aerial vehicles 300 of the switching timing using a simple configuration (for example, switching information with a bit length of 1 bit).

[0080] [Other embodiments] Although the present invention has been described by the above disclosure, the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. From this disclosure, various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art.

[0081] Although not specifically mentioned in the above disclosure, unmanned aerial vehicle 300 may be interpreted as a wireless relay device.

[0082] Although not specifically mentioned in the above disclosure, the switching information does not have to be TMCC information. The switching information may be any information that can be inserted into a frame. For example, the switching information may be included in an AC (Auxiliary Channel). The switching information may be a specific symbol that constitutes a frame.

[0083] Although not specifically mentioned in the above disclosure, the switching information does not have to be TMCC information. The switching information may be transmitted to unmanned aerial vehicle 300 via a communication network. The communication network may include, but is not limited to, the Internet or a mobile communication network. The switching information may be a type of telemetry signal. In such a case, the switching information may be transmitted to a receiving device (e.g., second device 200) via the communication network.

[0084] Although not specifically mentioned in the above disclosure, the unmanned aerial vehicle 300 may employ non-regenerative relaying, which relays signals without decoding the signals, or the unmanned aerial vehicle 300 may employ regenerative relaying, which involves decoding the signals.

[0085] Although not specifically mentioned in the above disclosure, a program may be provided that causes a computer to execute each process performed by the ground system 100 and the unmanned aerial vehicle 300. The program may also be recorded on a computer-readable medium. Using the computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0086] Alternatively, a chip may be provided that is configured with a memory that stores programs for executing the processes performed by ground system 100 and unmanned aerial vehicle 300 and a processor that executes the programs stored in the memory.

[0087] (Addendum) The above disclosure may be expressed as follows:

[0088] The first feature is a ground system comprising a transmitting unit that transmits frames to an unmanned aerial vehicle to be relayed by the unmanned aerial vehicle, a receiving unit that receives a signal from the unmanned aerial vehicle indicating that synchronization of the frames has been established in the unmanned aerial vehicle, and a control unit that controls the transmission of switching information that notifies the unmanned aerial vehicle of the timing to start or stop relaying the frames in response to the signal indicating that synchronization of the frames has been established.

[0089] A second feature is the terrestrial system in the first feature, wherein the switching information is part of a transmission parameter of the frame.

[0090] A third feature is a terrestrial system according to the first or second feature, wherein possible values ​​of the switching information include a value that instructs starting or stopping relaying of the frame, and a value that does not instruct starting or stopping relaying of the frame.

[0091] A fourth feature is an unmanned aerial vehicle comprising: a repeater that receives a frame to be relayed by the unmanned aerial vehicle from a ground system and relays the frame received from the ground system; a transmitter that transmits a signal to the ground system indicating that synchronization of the frame has been established in the unmanned aerial vehicle; and a control unit that controls the start or stop of relaying the frame based on switching information that notifies the unmanned aerial vehicle of the timing to start or stop relaying the frame, wherein the switching information is transmitted in response to the signal indicating that synchronization of the frame has been established.

[0092] A fifth feature is the unmanned aerial vehicle of the fourth feature, wherein the control unit controls the unmanned aerial vehicle to start relaying the frame in accordance with the switching information when relaying of the frame is not being performed.

[0093] A sixth feature is an unmanned aerial vehicle according to the fourth or fifth feature, wherein the control unit controls the unmanned aerial vehicle to stop relaying the frame in accordance with the switching information when relaying the frame is being performed.

[0094] A seventh feature is a wireless relay system comprising an unmanned aerial vehicle and a ground system that transmits frames to be relayed by the unmanned aerial vehicle, wherein the unmanned aerial vehicle transmits a signal to the ground system indicating that synchronization of the frames has been established in the unmanned aerial vehicle, the ground system transmits switching information in response to the signal indicating that synchronization of the frames has been established, notifying the unmanned aerial vehicle of the timing to start or stop relaying the frames, and the unmanned aerial vehicle controls the start or stop of relaying the frames based on the switching information. [Explanation of symbols]

[0095] 10: Wireless relay system, 100: First device, 110: High frequency unit, 120: Receiving unit, 130: Control unit, 200: Second device, 300: Unmanned aerial vehicle, 310: Repeater, 320: Transmitting unit, 330: Control unit

Claims

1. a transmitter that transmits a frame to be relayed by the unmanned aerial vehicle to the unmanned aerial vehicle; a receiving unit that receives a signal from the unmanned aerial vehicle indicating that the frame synchronization has been established in the unmanned aerial vehicle; A ground system comprising: a control unit that controls the transmission of switching information that notifies the unmanned aerial vehicle of the timing to start or stop relaying the frame in response to a signal indicating that frame synchronization has been established.

2. The ground system according to claim 1 , wherein the switching information is part of transmission parameters of the frame.

3. The ground system according to claim 1 , wherein possible values ​​of the switching information include a value that instructs the start or stop of relaying the frame, and a value that does not instruct the start or stop of relaying the frame.

4. An unmanned aerial vehicle, a repeater that receives a frame to be relayed by the unmanned aerial vehicle from a ground system and relays the frame received from the ground system; a transmitter in the unmanned aerial vehicle that transmits a signal indicating that the frame synchronization has been established to the ground system; a control unit that controls the start or stop of relaying the frame based on switching information that notifies the unmanned aerial vehicle of a timing to start or stop relaying the frame, An unmanned aerial vehicle, wherein the switching information is transmitted in response to a signal indicating that frame synchronization has been established.

5. The unmanned aerial vehicle according to claim 4 , wherein the control unit controls the unmanned aerial vehicle to start relaying the frame in response to the switching information when relaying the frame is not currently being performed.

6. The unmanned aerial vehicle according to claim 4 , wherein the control unit, when relaying the frame, controls to stop relaying the frame in accordance with the switching information.

7. Unmanned aerial vehicles and a ground system that transmits frames to be relayed by the unmanned aerial vehicle; the unmanned aerial vehicle transmits a signal to the ground system indicating that the frame synchronization has been established at the unmanned aerial vehicle; the ground system transmits switching information notifying the unmanned aerial vehicle of a timing to start or stop relaying the frame in response to a signal indicating that synchronization of the frame has been established; A wireless relay system in which the unmanned aerial vehicle controls the start or stop of relaying the frame based on the switching information.

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