COMMUNICATION PROCESSING CIRCUIT AND COMMUNICATION PROCESSING METHOD

Abstract

To provide a technique for achieving flexible communication by setting communication opportunities on demand that are not in a predetermined communication schedule in inter-satellite optical communication.SOLUTION: One aspect of the present disclosure includes: an orbit prediction unit that predicts the orbit of a relay satellite that relays communication between a satellite having an optical communication unit and an earth station; a communication planning unit that creates a communication plan between the satellite and the relay satellite; a setting unit that sets an unplanned communication period during which there is a possibility of unplanned communication between the satellite and the relay satellite; and a creation unit that creates control information for controlling the optical communication unit so that the optical communication unit points to and tracks the relay satellite over the unplanned communication period based on the predicted orbit.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to a satellite operation device. [Background technology]

[0002] A technology is being considered for communication between satellites (for example, observation satellites, communication satellites, etc.) operated by user companies and other operators and earth stations via relay satellites. In this technology, the use of inter-satellite optical communications, in which inter-satellite communications are carried out via optical communications between satellites and relay satellites, is being considered.

[0003] In the inter-satellite optical communications that have been considered so far, communications between relay satellites and satellites are carried out according to a communication plan (hereinafter referred to as a communication schedule or scheduling) that is set in advance based on the relative positions of the relay satellite orbiting in a medium earth orbit and the satellite orbiting in a low earth orbit. The relay satellite establishes a communication connection with a specified satellite according to the set schedule, and transmits and receives data to and from that satellite.

[0004] Known space optical communication technologies can be applied to inter-satellite optical communications. For example, Japanese Patent Application Laid-Open No. 2001-203641 discloses a free-space optical transmission device capable of tracking and pointing in free-space optical communications. Japanese Patent Application Laid-Open No. 2016-100855 also discloses a transceiver that transmits data and control information superimposed on each other in free-space optical communications. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-203641 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-100855 Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional inter-satellite optical communications, relay satellites and satellites can only communicate during the time periods set in the communication schedules that are set in advance by the operators of each satellite, resulting in a lack of flexibility in communication opportunities. Therefore, even if the operators of satellites want to communicate with and obtain data from satellites immediately during periods that are not set in the communication schedule, there is a problem in that it is not possible to meet their needs.

[0007] The present disclosure aims to provide a technology that realizes flexible communication by enabling communication opportunities that are not included in a predetermined communication schedule in inter-satellite optical communication to be set on demand. [Means for solving the problem]

[0008] One aspect of the present disclosure is A communication processing circuit of a satellite that performs optical communication with a relay satellite, the communication processing circuit comprising: a processing unit that processes data transmitted by optical communication to the relay satellite; a communication establishment unit that establishes unplanned communication that is not planned in advance with the relay satellite; a receiving unit that receives position information that indicates the position of the relay satellite during an unplanned communication period in which the unplanned communication is likely to occur; and a control unit that controls pointing and tracking of the relay satellite throughout the unplanned communication period based on the position information. . [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a technology for realizing flexible communication by enabling communication opportunities that are not included in a predetermined communication schedule in inter-satellite optical communication to be set on demand. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a schematic diagram illustrating a satellite and a relay satellite according to an embodiment of the present disclosure. [Figure 2] 1 is a schematic diagram illustrating a communication range between an earth station and a satellite according to an embodiment of the present disclosure. [Figure 3] FIG. 2 is a schematic diagram illustrating communication between an earth station and a satellite via a relay satellite according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a block diagram showing a hardware configuration of a satellite and a relay satellite according to an embodiment of the present disclosure. [Figure 5] FIG. 2 is a block diagram illustrating a hardware configuration of a communication planning device according to an embodiment of the present disclosure. [Figure 6]FIG. 2 is a block diagram showing a functional block configuration of a satellite according to an embodiment of the present disclosure. [Figure 7] FIG. 2 is a block diagram showing a functional block configuration of a relay satellite according to an embodiment of the present disclosure. [Figure 8] 1 is a block diagram showing a functional block configuration of a communication planning device according to an embodiment of the present disclosure. [Figure 9] FIG. 2 is a schematic diagram illustrating a procedure for initiating unplanned communication according to an embodiment of the present disclosure. [Figure 10] FIG. 10 is a sequence diagram illustrating an example of operation of a satellite system before it becomes ready for unplanned communication in an embodiment of the present disclosure. [Figure 11] FIG. 10 is a sequence diagram illustrating an example of the operation of a satellite system at the start of unplanned communication in an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] A satellite system according to an embodiment of the present disclosure will now be described with reference to the drawings.

[0012] [Satellite System] As shown in FIG. 1, the satellite system 10 includes an earth station 50, a satellite 100, a relay satellite 200, and a communication planning device 300. Although FIG. 1 shows three satellites 100 and two relay satellites 200, the present disclosure is not limited thereto. The number of satellites 100 may be one or a number other than three. The number of relay satellites 200 may be one or a number other than two. Furthermore, to ensure constant communication with the relay satellites 200 orbiting the Earth, multiple earth stations 50 may be located in multiple countries or regions on Earth.

[0013] In this embodiment, the satellite 100 and the relay satellite 200 orbit the Earth in different orbits. For example, if the satellite 100 is an observation satellite, a satellite constellation may be constructed of the multiple satellites 100 and the multiple satellites 100 may orbit in a predetermined arrangement so that the entire Earth can be observed using the multiple satellites 100.

[0014] The satellite 100 is an artificial satellite that has a predetermined function and orbits at a predetermined altitude, such as an observation satellite or a communication satellite, without being limited thereto.

[0015] The relay satellite 200 functions as a relay station for transmitting and receiving data between the earth station 50 and the satellite 100, without limitation. In this embodiment, the relay satellite 200 orbits at a higher altitude than the satellite 100. Typically, the relay satellite 200 can cover a plurality of satellites 100.

[0016] For example, the satellite 100 orbits in a low earth orbit (LEO). The low orbit is located, for example, at an altitude of approximately 20 km to 2,000 km above the Earth's surface. Also, for example, the relay satellite 200 orbits in a medium earth orbit (MEO). The medium earth orbit is located, for example, at an altitude of approximately 1,000 km to 36,0000 km above the Earth's surface. As a result, the positions of the satellite 100 and the relay satellite 200 as seen from the earth station 50 change over time. Also, the relative positions of the satellite 100 and the relay satellite 200 also change over time.

[0017] The earth station 50 is a communication station that communicates with the satellite 100 directly or via the relay satellite 200. In addition, when there are multiple earth stations 50, the relay satellite operator 30 may use a certain earth station 50_1 (not shown) only for communication with the relay satellite 200, and not for communication with the satellite 100 via the relay satellite 200. In the example shown in FIG. 1 , the earth station 50 is installed on the ground, but the earth station in the present disclosure is not limited to this. The earth station in the present disclosure may be, for example, a communication station of a non-terrestrial network (NTN) constructed in the stratosphere or the like. The earth station 50 may be communicatively connected to the relay satellite operator 30, the satellite operator 40, and the communication planning device 300 via a network 20 such as the Internet. Information acquired by the earth station 50 from the satellite 100 is passed to the relay satellite operator 30, the satellite operator 40, and / or the communication planning device 300 via the Internet.

[0018] 2, the range in which an earth station 50 can communicate with a satellite 100 is determined by the visible range of the earth station 50. In the example shown in Fig. 2, the earth station 50 can communicate with a satellite 100_2 that is within the communication range, but cannot communicate with a satellite 100_1 that is within the non-communication range.

[0019] On the other hand, as shown in FIG. 3, the earth station 50 can use the relay satellite 200 that is present within the communication range to communicate with the satellite 100_1 that is present within the communication non-range via the relay satellite 200.

[0020] The communication planning device 300 is a device that makes a communication plan for inter-satellite optical communication between the satellite 100 and the relay satellite 200. The communication planning device 300 is, for example, a computer such as a PC (Personal Computer). The communication planning device 300 is managed and / or operated by, for example, a relay satellite operator 30. Details of the communication planning device 300 will be described later.

[0021] [Summary of the Disclosure] Communication between the earth station 50 and the satellite 100 via the relay satellite 200 is usually performed based on a preset communication schedule. The communication schedule is a schedule set in advance by the relay satellite operator 30 and / or the satellite operator 40, which indicates the time or time period during which communication between the earth station 50 and the satellite 100 will be performed via the relay satellite 200. The communication schedule is set in advance for a predetermined period of time starting from a predetermined time after the current time, for example, and is shared throughout the entire satellite system 10.

[0022] The predetermined period is set to, for example, 24 hours or 48 hours. The communication schedule is set based on the predicted orbits of the satellite 100 and the relay satellite 200 for the predetermined period. In this embodiment, the communication schedule of a certain satellite 100 is set to include information indicating the time (time zone or time) for communication and which of the multiple relay satellites 200 is to relay the communication.

[0023] In this specification, communication according to a communication schedule, i.e., communication that is planned in advance, is referred to as planned communication, and a period during which planned communication according to the communication schedule is performed is referred to as a planned communication period.

[0024] On the other hand, during periods other than the planned communication period, the satellite operator 40 or the relay satellite operator 30 may desire instantaneous communication between the earth station 50 and the satellite 100. To give a specific example, if the satellite 100 is an observation satellite and an event such as a natural disaster, such as an earthquake, tsunami, eruption, or fire, or a terrorist attack occurs in a certain region on Earth, the satellite operator 40 may want to immediately obtain observation data of the location of the event by the satellite 100. In such a case, the satellite operator 40 needs to request a communication opportunity that is not included in the predetermined communication schedule from the relay satellite operator 30, and set up communication between the satellite 100 and the earth station 50 via the relay satellite 200 on an on-demand basis.

[0025] In this embodiment, a technology for setting on-demand opportunities for inter-satellite optical communication that is not on a predetermined communication schedule during a period other than a predetermined planned communication period will be described in detail. In the following description, communication between satellite 100 and relay satellite 200 that is not on a predetermined communication schedule and that is performed during a period other than a planned communication period will be referred to as unplanned communication. Also, a period during which satellite 100 may receive a signal requesting unplanned communication from relay satellite 200 will be referred to as an unplanned communication period.

[0026] [Hardware configuration of satellite and relay satellite] The satellite 100 and the relay satellite 200 have, for example, the hardware configuration shown in Fig. 4. The satellite 100 and the relay satellite 200 each have hardware classified into a command and data handling system 101, a mission system 102, a communication system 103, a mechanical and thermal structure system 104, an attitude control system 105, and a power supply system 106.

[0027] The command and data handling system 101 processes received commands, as well as status data, mission data, etc. For example, the command and data handling system 101 has a processing circuit for data processing, and uses this processing circuit to realize various functional units described below.

[0028] The mission system 102 realizes a function (mission) specific to each satellite. For example, if the satellite is an earth observation satellite, the mission system 102 may be composed of a sensor, a data processing device, etc. If the satellite is a communications satellite, the mission system 102 may be composed of a data relay antenna, communications equipment, etc.

[0029] The communication system 103 may be composed of communication equipment, an antenna, etc. that receives commands from the earth station 50 and transmits the satellite's status, satellite observation data, telemetry, etc. to the earth station 50. The communication system 103 of the satellite 100 also has a camera that captures images of the satellite's surroundings, captures images of non-terrestrial areas such as outer space, and is equipped with an optical communication system 103A that receives and emits beacon light and communication light for inter-satellite optical communication. For example, the camera constantly captures images of the non-terrestrial areas around the satellite at a predetermined frame rate (e.g., 30 fps) and passes the captured image frames of the non-terrestrial areas to the command and data handling system 101, etc.

[0030] The mechanism and thermal structure system 104 consists of the satellite body, movable deployable parts such as solar panels, and mechanisms for stabilizing the temperature inside the satellite and dissipating heat.

[0031] The attitude control system 105 is composed of sensors that measure the position and / or attitude of the satellite, thrusters that change the altitude and / or attitude of the satellite, and the like, and controls the position and / or attitude of the satellite in orbit.

[0032] The power supply system 106 controls and manages the power used in the satellite. For example, the power supply system 106 charges the battery with power generated by the solar cell and supplies the power required by each system in the satellite.

[0033] Note that the above-described hardware configuration is merely an example, and the satellite 100 and relay satellite 200 according to the present disclosure may be realized with other appropriate hardware configurations. Furthermore, the grouping of each system described above is merely an example, and the hardware configurations of the satellite 100 and relay satellite 200 may be described using other groupings. For example, the same equipment and mechanisms may be classified into different systems depending on the satellite's mission. For example, since the relay satellite 200's main mission is to relay data via optical communications, the optical communication equipment (e.g., cameras, optical transmission devices, etc.) and data relay equipment may be classified into the mission system 102. On the other hand, since the satellite 100's mission is Earth observation, etc., various sensors and data processing devices for observation may be classified into the mission system 102, and the optical communication equipment (e.g., cameras, optical transmission devices, etc.) for communication with the relay satellite 200 may be classified into the communication system 103.

[0034] [Hardware configuration of communication planning device 300] Next, the hardware configuration of the computer 1000 that constitutes the communication planning device 300 will be described with reference to Fig. 5. Fig. 2 is a diagram showing an example of the hardware configuration of the computer 1000.

[0035] The computer 1000 includes input devices 1001 such as a keyboard, mouse, and touchpad, output devices 1002 such as a display and speakers, a CPU (Central Processing Unit) 1003, a ROM (Read Only Memory) 1004, a RAM (Random Access Memory) 1005, a storage device 1006 such as a hard disk drive or SSD (Solid State Drive), a reading device 1007 that reads information from recording media such as a DVD-ROM (Digital Versatile Disk Read Only Memory) or USB (Universal Serial Bus) memory, and a transmitting / receiving device 1008 that communicates via a network, and each part is connected by a bus 1009.

[0036] The reading device 1007 then reads a program for realizing the functions of the communication planning device 300 from a recording medium on which the program is recorded, and stores the program in the storage device 1006. Alternatively, the transmitting / receiving device 1008 communicates with a system device connected to the network, and stores the program for realizing the functions of the communication planning device 300 downloaded from the system device in the storage device 1006.

[0037] Then, the CPU 1003 copies the program stored in the storage device 1006 to the RAM 1005, and sequentially reads out and executes instructions contained in the program from the RAM 1005, thereby realizing the functions of the communication planning device 300.

[0038] [Satellite software configuration] Next, with reference to FIG. 6, a functional block configuration of the satellite 100 according to an embodiment of the present disclosure will be described.

[0039] 6, satellite 100 has a communication unit 110, an optical communication unit 120, and a tracking unit 130. The processing of each functional block can be realized by any of the systems included in the hardware configuration described above, software that controls the systems included in the hardware configuration, or a combination thereof.

[0040] The communication unit 110 communicates with the earth station 50. This enables data transmission and reception between the satellite 100 and the earth station 50 while the satellite 100 is within the communication range of the earth station 50. The communication unit 110 receives, from the earth station 50, communication schedule information for planned communication with the relay satellite 200 in the planned communication period, and control information for pointing and tracking the relay satellite 200 in the non-planned communication period. Details of the control information will be described later.

[0041] The optical communication unit 120 performs inter-satellite optical communication with the relay satellite 200. The optical communication unit 120 includes a beacon light detection unit 121, a communication establishment unit 122, and a communication execution unit 123.

[0042] The beacon light detection unit 121 detects beacon light transmitted from the relay satellite 200 based on the communication schedule at the start of inter-satellite optical communication with the relay satellite 200 during the planned communication period. The beacon light detection unit 121 also detects beacon light transmitted from the relay satellite 200 in response to a communication request received from the earth station 50 during the unplanned communication period. The beacon light detection unit 121 acquires optical signals from an image of an area including the relay satellite 200 captured by a camera included in the satellite 100, extracts bright spots that are beacon light candidates through image processing, and detects beacon light based on a determination process for the extracted bright spots. Alternatively, the beacon light detection unit 121 may detect beacon light directly received from a specific relay satellite 200 that is being point-tracked by the point-tracking unit 130 (described later). In this case, the satellite 100 does not need to have a camera, which reduces the manufacturing cost of the satellite 100.

[0043] When the beacon light detection unit 121 detects a beacon light including a communication request for the satellite itself, the communication establishment unit 122 starts a procedure for establishing communication with the relay satellite 200. For example, the communication establishment unit 122 transmits a response signal indicating a response to the communication request included in the beacon light to the relay satellite 200, and establishes a communication connection between the relay satellite 200 and the satellite 100 according to a predetermined communication establishment procedure. The response signal includes, for example, the identifier of the satellite 100 and the identifier of the relay satellite 200.

[0044] When a communication connection with the relay satellite 200 is established, the communication execution unit 123 executes inter-satellite optical communication with the relay satellite 200 using communication light. If communication cannot be established for some reason, the optical communication unit 120 executes a predetermined number of retries. If communication cannot be established even after the retries, the satellite 100 may notify the relay satellite operator 30 and / or the satellite operator 40 via the earth station 50 of information indicating that communication could not be established.

[0045] The tracking unit 130 controls the optical communication unit 120 so that the optical communication system 103A (see FIG. 4) tracks the specific relay satellite 200 during the unplanned communication period based on control information including position information of the specific relay satellite 200 to be tracked during the unplanned communication period. This makes it easier for the optical communication unit 120 to detect beacon light from the specific relay satellite 200 during the unplanned communication period, and enables unplanned communication to be established in a short time.

[0046] [Software configuration of relay satellite 200] Next, with reference to FIG. 7, a software configuration of the relay satellite 200 according to an embodiment of the present disclosure will be described.

[0047] [Relay satellite] 7, the relay satellite 200 has a communication unit 210 and an optical communication unit 220. The functions of each piece of software can be realized by any one or a combination of the systems included in the above-mentioned hardware configuration.

[0048] The communication unit 210 communicates with the earth station 50. This enables data transmission and reception between the relay satellite 200 and the earth station 50. The communication unit 210 receives, from the earth station 50, communication schedule information for planned communication with the relay satellite 200 in the planned communication period, and communication request information including a request to start unplanned communication with the satellite 100 in the unplanned communication period.

[0049] The optical communication unit 220 performs inter-satellite optical communication with the satellite 100. The optical communication unit 220 includes an optical signal transmitting / receiving unit 221, a communication establishing unit 222, and a communication executing unit 223.

[0050] The optical signal transmitting / receiving unit 221 transmits beacon light to the satellite 100 in response to communication schedule information or communication request information received from the earth station 50, and receives a response signal from the satellite 100 that detects the beacon light. For example, the beacon light may be an optical signal with lower directivity (larger divergence angle) than the communication light transmitted after an optical communication connection with the satellite 100 is established. In this case, the beacon light is transmitted over a relatively wider area than the communication light, making it easier for the satellite 100 to receive the beacon light. Alternatively, the optical signal transmitting / receiving unit 221 may scan an optical signal with the same level of directivity as the communication light or higher (smaller divergence angle) toward a range where the satellite 100 may be located.

[0051] The optical signal transmitting / receiving unit 221 may transmit a beacon light having a predetermined blinking pattern that indicates the encoded information. The blinking pattern allows the satellite 100 receiving the beacon light to determine whether the beacon light is intended for the satellite.

[0052] When the optical signal transmitting / receiving unit 221 receives a response signal from the satellite 100, it determines whether the received response signal is addressed to the satellite itself based on the identifier of the satellite 100 and the identifier of the relay satellite 200 contained in the response signal.

[0053] When the optical signal transmitting / receiving unit 221 receives a response signal addressed to the satellite, the communication establishment unit 222 starts a procedure for establishing communication with the satellite 100. For example, the communication establishment unit 222 establishes a communication connection between the relay satellite 200 and the satellite 100 in accordance with a predetermined communication establishment procedure.

[0054] When a communication connection with the satellite 100 is established, the communication execution unit 223 executes inter-satellite optical communication with the satellite 100 using communication light. If communication cannot be established for some reason, the optical communication unit 220 executes a predetermined number of retries. If communication cannot be established even after the retries, the relay satellite 200 may notify the relay satellite operator 30 and / or the satellite operator 40 via the earth station 50 of information indicating that communication could not be established.

[0055] [Functional Block Configuration of Communication Planning Device 300] Next, with reference to FIG. 8, a functional block configuration of the communication planning device 300 according to an embodiment of the present disclosure will be described.

[0056] As shown in FIG. 8, the communication planning device 300 includes a communication unit 310, a trajectory prediction unit 320, and a creation unit 330.

[0057] The communication unit 310 communicates with the satellite 100 and / or the relay satellite 200 via the network 20 and the earth station 50. This allows the communication unit 310 to transmit various types of information to the satellite 100 and / or the relay satellite 200.

[0058] The orbit prediction unit 320 predicts the orbit of the satellite 100 and / or the relay satellite 200 during the planned communication period. The orbit prediction unit 320 further predicts the orbit of the satellite 100 and the relay satellite 200 during the unplanned communication period. Known techniques can be used by the orbit prediction unit 320 to predict the orbit of the satellite 100 and the relay satellite 200. One example of the orbit prediction technique is one that uses a Kalman filter. The orbit prediction unit 320 may receive orbit prediction information for the satellite 100 from the satellite operator 40 of the satellite 100.

[0059] The creation unit 330 creates control information to be transmitted to the satellite 100 and communication request information to be transmitted to the relay satellite 200 in order to perform unplanned communication between the satellite 100 and the relay satellite 200. The control information may be created by the satellite operator 40 of the satellite 100 based on the orbit of the relay satellite 200 during the unplanned communication period predicted by the orbit prediction unit 320. The control information created by the creation unit 330 may be transmitted to the satellite operator 40 that operates the satellite 100, and the satellite operator 40 may further create overall control information including the control information for controlling the operation of the entire satellite 100.

[0060] First, in preparation for performing unplanned communication, the creation unit 330 sets a specific period from a specific time after the current time in the reference time of the satellite system 10 as an unplanned communication period, and creates control information for controlling the optical communication unit 120 of the satellite 100 so that the optical communication system 103A tracks the pointing of a specific relay satellite 200 during the unplanned communication period. The control information created by the creation unit 330 is merely information for causing the satellite 100 to control the optical communication unit 120, and is not information for controlling the operation of the entire satellite. As described above, the overall control information for controlling the operation of the entire satellite 100 may be created by the satellite operator 40.

[0061] An example of an unplanned communication period is a desired 24-hour or 48-hour period based on the reference time of the satellite system 10. Specifically, if the current time of the satellite system 10 is 9:00 AM on March 1, the creation unit 330 may set the 48 hours from 12:00 AM on March 1 to 12:00 AM on March 3 as the unplanned communication period. These times are merely examples and may be changed as appropriate. For example, if the satellite 100 is an earth observation satellite and the satellite operator 40 wishes to acquire data on demand from the satellite 100 during a specific period in the future, the satellite operator 40 requests the relay satellite operator 30 to set an unplanned communication period for that specific period. Furthermore, an unplanned communication period can be set for each of multiple satellites 100. An unplanned communication period is not set only once; new unplanned communication periods can be set as time passes. For example, after the 48 hours from 12:00 AM on March 1st to 12:00 AM on March 3rd are set as an unplanned communication period, as time passes, the 48 hours from 12:00 AM on March 3rd to 12:00 AM on March 5th may be set as a new unplanned communication period.

[0062] In this embodiment, the unplanned communication period is set to 24 hours or 48 hours as a result of balancing the amount of calculation by the creation unit 330 for predicting the orbits of the satellite 100 and / or relay satellite 200 during the planned communication period with the frequency of uplinking control information to the satellite 100. If the calculation resources of the creation unit 330 are sufficiently large, the unplanned communication period may be set to a longer period. On the other hand, if it is acceptable to increase the frequency at which the control information and communication request information created by the creation unit 330 are transmitted to the satellite 100 or relay satellite 200 via the earth station 50, the unplanned communication period may be set to a shorter period. The orbit prediction and position information of the satellite 100 and relay satellite 200 are calculated and identified, for example, based on a solar system barycenter celestial reference coordinate system.

[0063] The creation unit 330 creates control information including position information of a specific relay satellite 200 that the satellite 100 should track during the unplanned communication period, based on the predicted orbits of the satellite 100 and the relay satellite 200. More specifically, the creation unit 330 identifies the direction in which the optical communication system 103A of the satellite 100 should be pointed, based on the relative positions of the satellite 100 and the relay satellite 200 estimated based on the predicted orbits at each point in the unplanned communication period, and creates control information to point the optical communication system 103A in the identified direction.

[0064] The control information may include, for example, the following information: identification information (such as a preset ID) of the satellite 100 that is the target of the unplanned communication, the start time (absolute time) of the unplanned communication, predicted position coordinate information of the satellite 100 at a predetermined interval (for example, every second) and its error range, etc. Note that the coordinate system used for the predicted position coordinate information may be a solar system barycentric celestial body reference coordinate system, a geocentric inertial coordinate system, a geocentric Earth-fixed coordinate system, or the like.

[0065] In this embodiment, since there are multiple relay satellites 200, when unplanned communication with a certain satellite 100 is desired, it is necessary to select a relay satellite 200 from the multiple relay satellites 200 to relay communication with the satellite 100. In this specification, the relay satellite 200 to relay communication with the satellite 100 may be referred to as the first relay satellite 200_1.

[0066] When creating the communication request information, the creation unit 330 estimates the positional relationship between the earth station 50, the satellite 100, and the relay satellite 200 at each point in time during the unplanned communication period based on the predicted orbit, and determines which relay satellite 200 to use for relaying based on the positional relationship. The creation unit 330 or the satellite operator 40 derives the direction in which the first relay satellite 200_1, as determined from the satellite 100, is located at each point in time during the unplanned communication period, and creates control information to be transmitted to the satellite 100. Note that the positional relationship between the earth station 50, the satellite 100, and the relay satellite 200 is constantly changing, so that it may become necessary over time to change the relay satellite 200 to be used for relaying among the multiple relay satellites 200. In this case, the control information is information for controlling the optical communication system 103A to point in a direction in which a different relay satellite is located before and after a certain time.

[0067] The control information created by the creation unit 330 or the satellite operator 40 is uplinked to the satellite 100 via the earth station 50. Upon receiving the control information, the satellite 100 directs the optical communication system 103A in the direction indicated by the control information throughout the unplanned communication period. The direction indicated by the control information is the direction in which the first relay satellite 200_1 is located as seen from the satellite 100 at that time. This enables the satellite 100 to reliably detect a beacon light that requests the start of unplanned communication when the beacon light is transmitted from the relay satellite 200 during the unplanned communication period. Because the control information indicates the direction at each time point during the unplanned communication period, the satellite 100 can continue to point and track the optical communication system 103A toward the direction in which the relay satellite 200 is located during the unplanned communication period.

[0068] It is desirable to determine the start time of the unplanned communication period taking into consideration the time from the current time of the satellite system 10 until the creation unit 330 creates the control information, the control information is received by the satellite 100, and the optical communication system 103A is directed in the direction in which the relay satellite 200 is located.

[0069] In this way, the control information created by the creation unit 330 is received by the satellite 100, thereby completing preparations for unplanned communication between the satellite 100 and the first relay satellite 200_1 during the unplanned communication period. In the following description, a state in which the control information is transmitted to the satellite 100 and the optical communication system 103A of the satellite 100 is pointing and tracking the direction in which the first relay satellite 200_1 is located is referred to as an unplanned communication preparation completion state.

[0070] In the unplanned communication preparation complete state, unplanned communication between the satellite 100 and the first relay satellite 200_1 has not yet been performed. When a request to start unplanned communication is transmitted from the satellite operator 40 to the communication planning device 300 within the unplanned communication period, the creation unit 330 creates communication request information for actually starting the unplanned communication.

[0071] The communication request information includes the start time of the unplanned communication and the direction in which the satellite 100 is located as seen from the first relay satellite 200_1 at the start time. The start time of the unplanned communication is determined by, for example, the satellite operator 40.

[0072] The creation unit 330 derives the direction in which the satellite 100 is located as seen from the first relay satellite 200_1 based on the positional relationships among the earth station 50, the satellite 100, and the relay satellite 200 at each point in time during the unplanned communication period, which are estimated based on the predicted orbit. In this way, the creation unit 330 creates the communication request information.

[0073] The communication request information created by the creation unit 330 is uplinked to the first relay satellite 200_1 via the earth station 50. Upon receiving the communication request information, the first relay satellite 200_1 transmits a beacon light for starting optical communication in the direction included in the communication request information when the start period of the unplanned communication arrives.

[0074] During the unplanned communication period, the satellite 100 causes the optical communication system 103A to point and track the direction of the first relay satellite 200_1, so that the beacon light transmitted from the first relay satellite 200_1 is received by the optical communication unit 120. This makes it possible to start unplanned communication between the earth station 50 and the satellite 100 via the first relay satellite 200_1.

[0075] [Procedure for starting unplanned communication] Next, the procedure for starting unplanned communication will be described.

[0076] When the satellite operator 40 desires unplanned communication with a specific satellite 100, it transmits a request to start unplanned communication to the communication planning device 300. The communication planning device 300 transmits communication request information to a relay satellite 200 located in a position where optical communication with the satellite 100 is possible, via the earth station 50. Upon receiving the communication request information from the earth station 50, the relay satellite 200 transmits a beacon light onto the orbit around which the satellite 100 orbits. The beacon light may be, for example, a pulsed optical signal in which the identifier of the relay satellite 200 and the identifier of the communicating satellite 100 are encoded.

[0077] When satellite 100 receives the beacon light, it analyzes the contents, and if it determines that it has been requested by relay satellite 200 as the communication partner, it returns a response signal to establish a communication connection with relay satellite 200, the source of the beacon light. This establishes optical communication between satellite 100 and relay satellite 200, and unplanned communication between earth station 50 and satellite 100 via relay satellite 200 begins.

[0078] FIG. 9 shows an outline of a procedure for starting unplanned communication when unplanned communication between the earth station 50 and the satellite 100_3 among the plurality of satellites 100_1, 100_2, 100_3, and 100_4 is desired.

[0079] The earth station 50 transmits communication request information requesting communication with the satellite 100_3 to the relay satellite 200. The communication request information includes information indicating the direction of the satellite 100_3 as seen from the relay satellite 200, and the relay satellite 200 transmits a beacon light in that direction.

[0080] The satellite 100_3 receives the beacon light transmitted by the relay satellite 200. Here, the satellite 100_3 uses control information to control the optical communication unit 120 to control the optical communication system 103A so that the optical communication unit 120 performs pointing tracking in the direction in which the relay satellite 200 is located. Therefore, the satellite 100_3 can easily receive and detect the beacon light transmitted by the relay satellite 200.

[0081] When the satellite 100_3 detects the beacon light from the relay satellite 200, it extracts the identifier of the relay satellite 200 and the identifier of the requested communication partner encoded in the beacon light. The satellite 100_3 determines whether the extracted identifier of the communication partner matches its own identifier. In this example, since the identifier of the satellite 100_3 is included in the beacon light, the satellite 100_3 determines that it is requested as the communication partner according to a predetermined communication establishment procedure, and proceeds to a communication establishment procedure with the relay satellite 200. Once a communication connection between the satellite 100_3 and the relay satellite 200 is established according to a predetermined communication establishment procedure, the satellite 100_3 and the relay satellite 200 transmit and receive data via optical communication. The beacon light may also have a specific blinking pattern that does not include the identifier of the relay satellite 200. In this case, the satellite 100 that detects the beacon light may determine from the blinking pattern that the beacon light was transmitted from a predetermined relay satellite.

[0082] By using this procedure, unplanned communication between the earth station 50 and the satellite 100 via the relay satellite 200 can be started at a desired timing.

[0083] [Example of operation] The above describes the processing of each functional block included in the satellite system 10. Next, an example of the operation of the satellite system 10 before the start of an unplanned communication period and during the unplanned communication period will be described.

[0084] <Example of operation of satellite system 10 before entering unplanned communication preparation state> An example of the operation of each component of the satellite system 10 before it becomes ready for unplanned communication will be described with reference to FIG.

[0085] In step S1, the communication planning device 300 sets an unplanned communication period.

[0086] In step S2, the communication planning device 300 predicts the orbits of the satellite 100 and the relay satellite 200 during the unplanned communication period.

[0087] In step S3, the communication planning device 300 determines the relay satellite 200 that will perform relay at each time point in the unplanned communication period.

[0088] In step S4, the communication planning device 300 derives the direction of the relay satellite 200 as seen from the satellite 100.

[0089] In step S5, the communication planning device 300 generates control information for directing the direction of the relay satellite 200 to the optical communication system 103A of the satellite 100 at each point in time during the unplanned communication period.

[0090] In step S6, the communication planning device 300 transmits the control information to the earth station 50.

[0091] In step S7, the earth station 50 transmits (uplinks) the control information to the satellite 100. In step S7, the earth station 50 may transmit (uplinks) the control information to the satellite 100 via the relay satellite 200 using pre-planned planned communication, or may wait until the satellite 100 comes within the communication range of the earth station 50 and then uplink the control information directly to the satellite 100 without going through the relay satellite 200.

[0092] In step S8, the satellite 100, in accordance with the control information, causes the optical communication system 103A to point and track the relay satellite 200. This puts the satellite system 10 into a state where preparations for unplanned communication are complete.

[0093] <Example of operation of satellite system 10 at the start of unplanned communication> An example of the operation of the satellite system 10 at the start of unplanned communication will be described with reference to FIG.

[0094] In step S11, the communication planning device 300 receives a request to start unplanned communication from the satellite operator 40 or the like during an unplanned communication period.

[0095] In step S12, the communication planning device 300 determines a start time for the requested unplanned communication. For example, if the satellite operator 40 specifies a start time, the communication planning device 300 may use that time as the start time, or may determine the start time by taking into consideration the time required to create communication request information for the unplanned communication, the time required for uplinking to the relay satellite 200, the time required for communication preparation in the relay satellite 200, etc.

[0096] In step S13, the communication planning device 300 determines the first relay satellite 200_1 to relay the requested unplanned communication based on the predicted orbit.

[0097] In step S14, the communication planning device 300 derives the direction of the satellite 100 as seen from the first relay satellite 200_1 at the start time of the unplanned communication based on the predicted orbit.

[0098] In step S15, the communication planning device 300 generates communication request information including the position information of the satellite 100 for the first relay satellite 200_1.

[0099] In step S16, the communication planning device 300 transmits the communication request information to the earth station 50.

[0100] In step S17, the earth station 50 uplinks the communication request information to the first relay satellite 200_1.

[0101] In step S18, the first relay satellite 200_1 transmits beacon light to the satellite 100 to start optical communication based on the communication request information.

[0102] In step S19, inter-satellite optical communication is established between the first relay satellite 200_1 and the satellite 100.

[0103] In step S110, unplanned communication is performed between the earth station 50 and the satellite 100 via the first relay satellite 200_1.

[0104] 11 , in steps S16 and S17, the communication request information created by the communication planning device 300 is transmitted to the first relay satellite 200_1 via the earth station 50. However, the communication request information created by the communication planning device 300 may be transmitted to the relay satellite 200 via another earth station 50_1 that does not communicate with the satellite 100 but communicates with the relay satellite 200.

[0105] <Actions and Effects> As described above, according to the satellite system 10 of the present disclosure, the communication planning device 300 determines in advance which relay satellite 200 will relay communication between the earth station 50 and the satellite 100 during an unplanned communication period when unplanned communication that has not been planned in advance may occur, and creates control information that controls the optical communication unit 120 of the satellite 100 to cause the optical communication system 103A of the satellite 100 to point and track the determined relay satellite 200. This control information allows the satellite 100 to continue pointing in the direction of the relay satellite 200 that will perform relaying during the unplanned communication period.

[0106] As a result, when unplanned communication actually starts and beacon light is transmitted from relay satellite 200 to satellite 100 to establish inter-satellite optical communication, satellite 100 immediately receives the transmitted beacon light and can establish optical communication with relay satellite 200.

[0107] This configuration allows the satellite 100 to receive beacon light transmitted from the relay satellite 200 to the satellite 100 during the unplanned communication period.

[0108] Assuming that all communications are planned communications, as in the prior art, the satellite 100 only needs to control the optical communication system 103A to orient toward the relay satellite 200 to receive the beacon light from the relay satellite 200 immediately before the scheduled communication time (e.g., one minute before the start of communication). Therefore, the satellite 100 does not need to control the orientation of the optical communication system 103A outside of the communication period to reduce power consumption. Therefore, in a satellite system that can only perform planned communications planned in advance, it is extremely difficult to reliably perform unplanned communications outside of the planned communication time because the satellite is not prepared to receive the beacon light from the relay satellite. Even if the earth station 50 transmits a signal requesting unplanned communications to the relay satellite 200, it is difficult for the relay satellite 200 to establish optical communications with the satellite 100 due to the unplanned communications. Therefore, if the target satellite 100 is not within the communication range of the earth station 50, the earth station 50 must wait for the satellite 100 to come within communication range.

[0109] Furthermore, even if relay satellite 200 receives unplanned communication from earth station 50 and is able to transmit beacon light to satellite 100, if satellite 100 does not constantly capture relay satellite 200 in order to transmit beacon light, it is extremely unlikely that optical communication system 103A of satellite 100 will be able to receive the beacon light, and there is an extremely high possibility that inter-satellite optical communication will not be established.

[0110] On the other hand, in the satellite system 10 according to the present disclosure, a period during which unplanned communication may occur is set in advance, and during that period, the optical communication unit 120 of the satellite 100 is controlled so that the optical communication system 103A tracks the direction of the relay satellite 200. Therefore, when the relay satellite 200 immediately transmits a beacon light to the satellite 100 based on communication request information requesting unplanned communication, the possibility that the satellite 100 will reliably receive the beacon light and reliably establish optical communication with the relay satellite 200 can be increased.

[0111] In addition, the following supplementary notes are provided in relation to the above description. (Appendix 1) an orbit prediction unit that predicts the orbit of a relay satellite that relays communications between a satellite having an optical communication unit and an earth station; a generation unit that generates control information for controlling the optical communication unit so that the optical communication unit points to and tracks the relay satellite during an unplanned communication period in which unplanned communication, which is communication not planned in advance between the satellite and the earth station, may occur based on the predicted orbit; and A communication planning device comprising: (Appendix 2) the creation unit identifies a first relay satellite that will relay the unplanned communication among the plurality of relay satellites for each time period during the unplanned communication period based on the predicted orbit, and creates the control information so that the optical communication unit points to the first relay satellite for each time period. 2. The communications planning device of claim 1. (Appendix 3) the creation unit creates communication request information including a predicted position of the satellite when the earth station requests the satellite for the unplanned communication. 3. The communication planning device of claim 1 or 2. (Appendix 4) A satellite that communicates with an earth station via a relay satellite, a communication unit that receives, during an unplanned communication period in which unplanned communication, which is communication not planned in advance between the satellite and the earth station, is likely to occur, location identification information that identifies the location of the relay satellite that relays the unplanned communication; an optical communication unit that performs optical communication with the relay satellite; a pointing unit that causes the optical communication unit to point and track the relay satellite during the unplanned communication period based on the position identification information; A satellite comprising: (Appendix 5) An earth station, a satellite having an optical communication unit; a relay satellite that relays communications between the earth station and the satellite; a communication planning device that predicts the orbits of the satellite and the relay satellite, and creates control information to control the satellite so that the optical communication unit points to and tracks the relay satellite during an unplanned communication period in which unplanned communication, which is communication not planned in advance, may occur, based on the predicted orbits; Equipped with The satellite causes the optical communication unit to point and track the relay satellite based on the control information. Satellite system.

[0112] [Variations] Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the specific embodiments described above, and various modifications and variations are possible within the scope of the gist of the present disclosure as set forth in the claims.

[0113] In the above-described embodiment, an example has been described in which the control information includes information indicating the position or direction of the relay satellite as seen from the satellite 100. However, in the present disclosure, for example, the satellite 100 may store in advance orbit prediction data of multiple relay satellites 200, and the satellite 100 may itself estimate the position or direction of the relay satellite 200 indicated by the control information based on the orbit prediction data.

[0114] Similarly, in the above-described embodiment, an example has been described in which the communication request information includes information indicating the position or direction of the satellite 100 as seen from the first relay satellite 200_1. However, in the present disclosure, for example, the relay satellite 200 may store in advance orbit prediction data of multiple satellites, and may itself estimate the position or direction of the satellite 100 indicated in the communication request information based on the orbit prediction data of the satellite 100 to be relayed. [Explanation of symbols]

[0115] 10 Satellite Systems 20 Network 30 Relay satellite operators 40 Satellite operator 50 earth station 100 satellites 120 Optical Communications Department 121 Beacon light detector 122 Communication Establishment Unit 123 Communication Execution Unit 130 Directional tracking unit 200 relay satellites 210 Communications Department 220 Optical Communications Department 221 Optical signal transmitter / receiver 222 Communication Establishment Unit 223 Communications Execution Department 300 Communication Planning Device 310 Communications Department 320 Trajectory Prediction Unit 330 Creation Department

Claims

1. A communication processing circuit of a satellite that performs optical communication with a relay satellite, a processing unit that processes data transmitted to the relay satellite by the optical communication; a communication establishment unit that establishes unplanned communication with the relay satellite; a receiving unit that receives position information indicating a position of the relay satellite during an unplanned communication period in which the unplanned communication is likely to occur; a control unit that performs control to point and track the relay satellite throughout the unplanned communication period based on the location information; A communication processing circuit comprising:

2. The relay satellite is a relay satellite selected from a plurality of relay satellites, The relay satellite is identified for each time period in the unplanned communication period, the location information is location information indicating the location of the relay satellite; 2. The communication processing circuit according to claim 1.

3. A communication processing method executed in a communication circuit of a satellite that performs optical communication with a relay satellite, comprising: receiving location information indicating a location of the relay satellite during an unplanned communication period in which unplanned communication is likely to occur; performing control to point and track the relay satellite during the unplanned communication period based on the location information; Detecting a beacon light from the relay satellite; establishing the unplanned communication with the relay satellite; Processing data related to optical communication with the relay satellite; Communication processing method.

4. The relay satellite is a relay satellite selected from a plurality of relay satellites, The relay satellite is identified for each time period in the unplanned communication period, the location information is location information indicating the location of the relay satellite; The communication processing method according to claim 3 .

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