Communication system, communication control method, and computer program

Abstract

This communication system comprises: a first ground station that wirelessly communicates with a non-ground station; a plurality of ground relay stations that receive a signal transmitted from the first ground station via the non-ground station and relay the signal toward a destination of the signal via an optical communication network; and a switching device that switches a communication path to which the plurality of ground relay stations are connected in the optical network.

Description

Communication System, Communication Control Method, and Computer Program

[0001] The present invention relates to a communication system, a communication control method, and a computer program.

[0002] Communication in non-terrestrial networks (Non-Terrestrial Network: NTN) such as satellite communication and HAPS uses high-frequency bands, so it is vulnerable to deteriorating weather such as rain and fog. To address such issues, a communication system has been proposed that provides multiple ground stations (Hub stations) for relaying. In this communication system, when the feeder link quality at the Hub station during communication deteriorates, a switch to a path using another ground station is made. Also, all-optical networks such as those disclosed in Non-Patent Document 1 are expected.

[0003] Regarding the study of common base technologies for all-optical networks in the Innovative Information and Communication Technology (Beyond 5G (6G)) Fund Project, Ministry of Internal Affairs and Communications, International Strategy Bureau, Technology Policy Division, February 28, 2024, <URL:https: / / www.soumu.go.jp / main_content / 000930977.pdf>

[0004] However, generally, about several thousand communication paths are aggregated in one Hub station. Therefore, it takes a long time to switch the IP routing to switch the communication path using a certain Hub station to a communication path using another Hub station. As a result, communication delays and the like due to the switching process occur due to deteriorating weather. The present invention has been made in view of the above circumstances, and provides a stronger communication technology against changes in the communication environment such as deteriorating weather in a communication system using a non-terrestrial network.

[0005] One aspect of the present invention is a communication system including: a first ground station that wirelessly communicates with a non-terrestrial station; a plurality of ground relay stations that receive a signal transmitted from the first ground station, relay the signal to the destination of the signal via the non-terrestrial station and via an optical communication network; and a switch that switches a communication path to which the plurality of ground relay stations are connected in the optical network.

[0006] One aspect of the present invention is a communication system comprising: a first ground station that wirelessly communicates with a non-ground station; a plurality of ground relay stations that receive signals transmitted from the first ground station via the non-ground station and relay the signals to their destination via an optical communication network; a switch that switches communication paths to which the plurality of ground relay stations are connected in the optical network; and a control device, wherein the control device comprises an acquisition step of acquiring correlation information correlated with the communication environment for a ground relay station among the plurality of ground relay stations that is communicating with the non-ground station; and an instruction step of instructing the ground relay station communicating with the non-ground station and the switch to switch when the control device needs to switch the ground relay station communicating with the non-ground station to another ground relay station.

[0007] One aspect of the present invention is a computer program that causes a computer to execute the following steps in a communication system comprising: a first ground station that wirelessly communicates with a non-ground station; a plurality of ground relay stations that receive signals transmitted from the first ground station via the non-ground station and relay the signals to their destination via an optical communication network; and a switch in the optical network that switches the communication paths to which the plurality of ground relay stations are connected. The steps include: an acquisition step of acquiring correlation information correlated with the communication environment for a ground relay station among the plurality of ground relay stations that is communicating with the non-ground station; and an instruction step of instructing a control device to switch the ground relay station communicating with the non-ground station and the switch when the control device needs to switch the ground relay station communicating with the non-ground station to another ground relay station.

[0008] This invention makes it possible to provide a communication technology that is more resilient to changes in the communication environment, such as adverse weather conditions, in communication systems using non-terrestrial networks.

[0009] This is a schematic block diagram showing the system configuration of the communication system 100 of the present invention. This is a diagram showing a first specific example of equipment connected to the first ground station 10. This is a diagram showing a second specific example of equipment connected to the first ground station 10. This is a schematic block diagram showing a specific example of the functional configuration of the control device 70. This is a sequence chart showing an outline of the processing flow of the communication system 100. This is a diagram showing a modified example of the communication system 100. This is a diagram showing an outline of the hardware configuration example of the information processing device 90 applied to this embodiment.

[0010] Figure 1 is a schematic block diagram showing the system configuration of the communication system 100 of the present invention. The communication system 100 comprises a first ground station 10, a non-ground station 20, a first ground relay station, a first sensor 31, a second ground relay station 40, a second sensor 41, an optical communication network 50, a switch 60, a control device 70, and a second ground station 80.

[0011] Communication is conducted between the first ground station 10, the non-ground station 20, and multiple ground relay stations (in the case of Figure 1, the first ground relay station 30 and the second ground relay station) using a non-ground network. The first ground station 10 is a wireless communication device installed on the ground and performs wireless communication with the non-ground station 20. The first ground station 10 may be a wireless communication device using a portable (movable) antenna, or it may be a wireless communication device that is fixed or semi-fixed. The first ground station 10 may be configured as a communication terminal device itself (for example, a mobile phone or smartphone, etc.), or it may be configured as a wireless relay device such as Mobile Wi-Fi (registered trademark). The second ground station 80 is a communication device or an information processing device such as a server. The second ground station 80 may be, for example, a server or terminal device that is the communication destination of a terminal device that is communicatively connected to the first ground station 10. The second ground station 80 may be, for example, a communication device that relays communication between a terminal device that is communicatively connected to the first ground station 10 and a server or terminal device that is its communication destination.

[0012] Figure 2 shows a first specific example of equipment connected to the first ground station 10. The first ground station 10 may be installed in a facility 14 such as a residence, office, or building. In this case, a first repeater 11 may be connected to the first ground station 10. The first repeater 11 may be configured using, for example, a modem for non-ground station communication. A second repeater 12 is connected to the first repeater 11. Multiple second repeaters 12 may be connected to the first repeater 11.

[0013] The second repeater 12 is configured using, for example, IP network communication equipment such as a router. Terminal devices 13 are connected to the second repeater 12. The terminal devices 13 are information processing devices such as smartphones, tablets, or personal computers. The second repeater 12 and the terminal devices 13 may be connected via a communication protocol such as LAN or wireless LAN. Multiple terminal devices 13 may be connected to the second repeater 12.

[0014] Figure 3 shows a second specific example of equipment connected to the first ground station 10. The first ground station 10 may be provided, for example, as a wireless base station system. In this case, a first repeater 11 may be connected to the first ground station 10. A second repeater 12 is connected to the first repeater 11. Multiple second repeaters 12 may be connected to the first repeater 11.

[0015] The second repeater 12 is configured using IP network communication equipment such as a router. A wireless base station 15 is connected to the second repeater 12. The wireless base station 15 communicates wirelessly with wireless terminal devices 16. The wireless terminal devices 16 are wireless communication-capable information processing devices such as smartphones, tablets, and personal computers. Multiple wireless terminal devices 16 may be connected to the wireless base station 15.

[0016] Returning to the explanation of Figure 1, the non-ground station 20 comprises a mobile body located in the air away from the ground, and a wireless communication device installed on the mobile body. The mobile body may be, for example, an artificial satellite (e.g., a geostationary satellite, a low-Earth orbit satellite, or a high-Earth orbit satellite), a flying object, or an aircraft. As the flying object, an unmanned aerial vehicle such as a HAPS or a drone may be used, or a balloon may be used. The non-ground station 20 may function as a wireless base station or as a wireless relay station. If the non-ground station 20 functions as a wireless relay station, the second ground station may also function as a wireless base station.

[0017] The first ground relay station 30 is a communication device installed at a specific location on the ground. The first ground relay station 30 communicates wirelessly with the non-ground station 20. The first ground relay station 30 is connected to the second ground relay station 40 and the second ground station 80 via an optical communication network 50.

[0018] The first sensor 31 is a sensor installed in a physically close position to the first ground relay station 30. It is desirable that the distance between the first ground relay station 30 and the first sensor 31 be shorter than a predetermined length. The first sensor 31 acquires predetermined values ​​indicating the environment around the first ground relay station 30. The first sensor 31 acquires values ​​correlated with the communication environment of wireless communication between the first ground relay station 30 and the non-ground station 20. The first sensor 31 may be configured using, for example, an image sensor that photographs the sky and generates image data. The first sensor 31 may be configured using a precipitation sensor.

[0019] The second ground relay station 40 is configured using the same equipment as the first ground relay station 30. It is desirable that the second ground relay station 40 be located at a physical distance from the first ground relay station 30. For example, it is desirable that the second ground relay station 40 be located at a physical distance such that even if the communication environment between the first ground relay station 30 and the non-ground station 20 is poor due to rainfall, the communication environment between the second ground relay station 40 and the non-ground station 20 will be different. For example, it is desirable that each ground relay station be located at a predetermined distance (e.g., 100 km, 200 km, etc.) or more apart.

[0020] The second sensor 41 is a sensor installed in a physically close position to the second ground relay station 40. It is desirable that the distance between the second ground relay station 40 and the second sensor 41 be shorter than a predetermined length. The second sensor 41 is constructed using the same equipment as the first sensor 31.

[0021] The optical communication network 50 is configured using one or more optical communication devices and optical communication paths, including a switching device 60. The optical communication network 50 is configured using, for example, an all-optical network. An all-photonics network is a specific example of an all-optical network.

[0022] The switch 60 is a route switching device that switches the communication path of optical signals in the optical communication network 50 while keeping the optical signals. The switch 60 switches the communication path of optical signals in accordance with the control of the control device 70. For example, if the switch 60 receives a control signal from the control device 70 to switch all communication between the first ground relay station 30 and the second ground station 80 to communication between the second ground relay station 40 and the second ground station 80, the switch 60 changes the communication path of optical signals according to that control. For example, if the switch 60 receives a control signal from the control device 70 to switch only the optical signal communication of the frequency to be switched among the communication between the first ground relay station 30 and the second ground station 80 to communication between the second ground relay station 40 and the second ground station 80, the switch 60 changes the communication path of optical signals according to that control. In this case, the optical signal communication of frequencies that are not to be switched is maintained as communication between the first ground relay station 30 and the second ground station 80 even after the switching process of the switch 60 is performed.

[0023] The control device 70 is configured using an information processing device. The control device 70 controls the communication of the communication system 100. The control device 70 is connected to the first ground relay station 30, the first sensor 31, the second ground relay station 40, the second sensor 41, and the switch 60 so as to be communicative. Communication between the control device 70 and each device may be performed by optical communication, but is not necessarily required to be optical communication. The control device 70 acquires information correlated with the communication environments of the first ground relay station 30 and the second ground relay station 40 (hereinafter referred to as "correlation information") and determines whether or not the switch 60 needs to be switched. If the control device 70 determines that switching is necessary, it generates a switching control signal according to the determination result and transmits it to the first ground relay station 30, the second ground relay station 40, and the switch 60.

[0024] Figure 4 is a schematic block diagram showing a specific example of the functional configuration of the control device 70. The control device 70 is configured using information equipment such as a personal computer or a server. The control device 70 includes a communication unit 71, a storage unit 72, and a control unit 73.

[0025] The communication unit 71 is a communication device. The communication unit 71 may be configured, for example, as a network interface. The communication unit 71 communicates data with other devices (for example, the first ground relay station 30, the first sensor 31, the second ground relay station 40, the second sensor 41, and the switch 60) via the network in accordance with the control of the control unit 73. The communication unit 71 may be a device that performs wireless communication or a device that performs wired communication.

[0026] The storage unit 72 is configured using a storage device such as a magnetic hard disk drive or a semiconductor storage device. The storage unit 72 stores data used by the control unit 73.

[0027] The control unit 73 is configured using a processor such as a CPU (Central Processing Unit) and memory (main memory). The control unit 73 functions as a switching determination unit 731 and a switching control unit 732 when the processor executes a program. Note that all or part of the functions of the control unit 73 may be implemented using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The above program may be recorded on a computer-readable recording medium. Computer-readable recording media include, for example, portable media such as flexible disks, magneto-optical disks, ROMs, CD-ROMs, and semiconductor memory devices (e.g., SSDs: Solid State Drives), as well as storage devices such as hard disks and semiconductor memory devices built into computer systems. The above program may be transmitted via a telecommunications line.

[0028] The switching determination unit 731 acquires correlation information regarding the communication environments of the first ground relay station 30 and the second ground relay station 40, and determines whether or not the switching device 60 needs to be switched. Specific examples of correlation information include weather forecast information, current weather information, image data of the sky, and signal strength information between each ground relay station and the non-ground station 20. Based on the correlation information, the switching determination unit 731 determines the deterioration of the communication environment at the ground relay station 30 that is communicating on the non-ground network. If the correlation information satisfies predetermined deterioration conditions that indicate the communication environment has deteriorated to the point where switching is necessary, the switching determination unit 731 determines that switching is necessary.

[0029] Weather forecast information and information on current weather conditions may be obtained, for example, from a server that provides weather forecast information. Image data of the sky may be obtained from a server that provides such image data, or from the first sensor 31 and the second sensor 41. Signal strength information between non-ground stations and each ground relay station may be obtained from the first ground relay station 30 and the second ground relay station 40.

[0030] The switching determination unit 731 may determine whether or not a switch is necessary based on predetermined criteria. For example, if a ground relay station 30 (hereinafter referred to as the "operating ground relay station") that is currently communicating with a non-ground station 20 determines that there is a high probability of a continuous line failure, it may determine that it is necessary to switch the communication path to another ground relay station 30. In the following explanation, the ground relay station 30 to which the switch will be made will be referred to as the switching destination ground relay station.

[0031] More specifically, a switch may be determined to be necessary in the following situations: When the weather forecast predicts rain and that it will continue for a predetermined time or longer. Specifically, when the predicted rainfall exceeds a predetermined amount (e.g., 10 millimeters per hour) and that it will continue for a predetermined time (e.g., 1 hour) or longer. When the precipitation sensor is reacting at or above a predetermined level. In this case, a switch may be determined to be necessary regardless of whether the weather forecast predicts rain or not. When an image of the sky is input to a trained model and an output indicating that a switch is necessary is obtained. Such a trained model may be obtained, for example, by performing training processing using training data that combines multiple images of the sky and a ground truth label indicating whether a switch is necessary for the conditions of each image of the sky. When the antenna gain (received strength) falls below a predetermined value (e.g., 50 dBi). When time-series information of the antenna gain is input to a trained model and an output indicating that a switch is necessary is obtained. Such a trained model may be obtained, for example, by performing training processing using training data that combines time-series information of multiple antenna gains and a ground truth label indicating whether a switch is necessary for the conditions of each time-series information. When the communication environment of another ground relay station is better than the communication environment of the currently operating ground relay station.

[0032] The switching control unit 732 generates a control signal to switch part or all of the communication at the operational ground relay station to the communication at another ground relay station, according to the determination result of the switching determination unit 731. The switching control unit 732 transmits the generated control signal to the controlled devices (first ground relay station 30, second ground relay station 40, and switch 60). More specifically, the switching control unit 732 may perform the switching process as follows, for example.

[0033] First, the switching control unit 732 switches the non-terrestrial network to the target terrestrial relay station. Such a switch involves, for example, changing the frequency of the radio signals used in communication on the non-terrestrial network. Once the switching of the non-terrestrial network is complete, the switching control unit 732 instructs the switch 60 to switch the optical path. Once it is confirmed that there are no remaining terrestrial relay stations that have not yet been switched, the line switching is completed.

[0034] Let's explain the switching in more detail. As a premise, although only one first ground station 10 is shown in Figure 1, there may be multiple first ground stations 10. In this case, the non-ground stations 20 communicate with each first ground station 10 using radio signals in different frequency bands. Similarly, the first ground relay station 30 and the second ground relay station 40 communicate with the non-ground stations 20 using radio signals in different frequency bands. Each frequency band is one within a certain range. For example, suppose the first ground relay station 30 communicates with the non-ground station 20 using radio signals in frequency band A, and the second ground relay station 40 communicates with the non-ground station 20 using radio signals in frequency band B. When a part of the communication of the first ground relay station 30, which is functioning as an operational ground relay station (for example, communication with the second ground station 80), is switched to the second ground relay station 40, the non-ground stations 20 are notified of this. The non-ground stations 20 switch from sending data in frequency band A to communication in frequency band B. This process completes the switchover of the non-terrestrial network.

[0035] Subsequently, the switching control unit 732 instructs the switch 60 to switch, and the switch 60 switches the optical path. For example, the connection destination of the optical cable between the second ground relay station 40 and the switch 60 is switched from an optical cable connected to the first ground relay station 30, which was the operational ground relay station, to an optical cable connected to the second ground relay station 40, which will become the new operational ground relay station. At this time, the switching control unit 732 may also notify the second ground station 80 of the switch (for example, a change in IP routing on the second ground station 80 side). In this case, the second ground station 80 may change the settings of the transmission signal header etc. in accordance with the change in destination from the first ground relay station 30 to the second ground relay station 40.

[0036] Figure 5 is a sequence chart showing an overview of the processing flow of the communication system 100. First, the control device 70 repeatedly acquires correlation information at predetermined timings (step S101). The switching determination unit 731 determines whether or not to perform a switch based on the acquired correlation information (step S102). If the switching determination unit 731 determines that no switch is to be performed, the control device 70 waits until the next timing for acquiring correlation information without the switching control unit 732 performing any processing.

[0037] On the other hand, if the switching determination unit 731 determines that a switch should be performed, the switching control unit 732 generates a switching signal and transmits the switching signal to the active ground relay station and the target ground relay station (step S103). In the example in Figure 5, the first ground relay station 30 corresponds to the active ground relay station, and the second ground relay station 40 corresponds to the target ground relay station. The active ground relay station stops communication on the non-terrestrial network of the frequency to be switched (step S104), and the target ground relay station starts communication on the non-terrestrial network of the frequency to be switched (step S105). Subsequently, the switching control unit 732 transmits a control signal to the switcher 60 to instruct it to switch the optical path (step S106). The switcher 60 performs the switching process based on the switching signal (step S107).

[0038] In the communication system 100 configured in this way, it becomes possible to achieve more robust communication against changes in the communication environment, such as bad weather, in a communication system using a non-terrestrial network. Specifically, this is as follows: When the switching determination unit 731 of the control device 70 determines that the communication environment of the non-terrestrial network has deteriorated, such as due to bad weather, a switching process is performed in the optical communication network 50. Therefore, it is possible to complete the switching in a shorter time compared to the conventional case where the terrestrial relay station 30 and the second terrestrial station 80 are connected using a non-optical communication network. If the optical communication network 50 is constructed as an all-optical network, it is possible to complete the switching in an even shorter time. Therefore, it becomes possible to achieve more robust communication against changes in the communication environment, such as bad weather.

[0039] Figure 6 shows a modified example of the communication system 100. As shown in Figure 6, the communication system 100 may have three or more ground relay stations 30.

[0040] Figure 7 is a schematic diagram of an example hardware configuration of an information processing device 90 applied to this embodiment. The information processing device 90 comprises a processor 91, main memory 92, communication interface 93, auxiliary storage device 94, input / output interface 95, and internal bus 96. The processor 91, main memory 92, communication interface 93, auxiliary storage device 94, and input / output interface 95 are connected to each other via the internal bus 96 so as to be able to communicate with each other. The information processing device 90 may also be applied to, for example, a control device 70. In this case, for example, the communication unit 71 may be configured using the communication interface 93. For example, the storage unit 72 may be configured using the auxiliary storage device 94. Also, the control unit 73 may be configured using the processor 91 and the main memory 92.

[0041] The control device 70 may be implemented using multiple information processing devices. For example, the control device 70 may be implemented using a device such as a cloud. For example, in the control device 70, the storage unit 72 and the control unit 73 may be implemented in different information processing devices. For example, the storage unit 72 and the control unit 73 of the control device 70 may be distributed and implemented in multiple information processing devices.

[0042] While embodiments of this invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and includes designs and the like that do not depart from the spirit of this invention.

[0043] 100...Communication system, 10...First ground station, 20...Non-ground station, 30...First ground relay station, 31...First sensor, 40...Second ground relay station, 41...Second sensor, 50...Optical communication network, 60...Switching device, 70...Control device, 71...Communication unit, 72...Storage unit, 73...Control unit, 731...Switching determination unit, 732...Switching control unit, 80...Second ground station

Claims

1. A communication system comprising: a first ground station that communicates wirelessly with a non-ground station; a plurality of ground relay stations that receive signals transmitted from the first ground station via the non-ground station and relay the signals to their destination via an optical communication network; and a switch in the optical network that switches the communication paths to which the plurality of ground relay stations are connected.

2. The communication system according to claim 1, wherein the optical network is an all-optical network.

3. The communication system according to claim 1 or 2, further comprising a control device that acquires correlation information correlated with the communication environment for a ground relay station among the plurality of ground relay stations that is communicating with the non-ground station, and instructs the ground relay station communicating with the non-ground station and the switching device to switch when it is necessary to switch the ground relay station communicating with the non-ground station to another ground relay station.

4. A communication system comprising: a first ground station that wirelessly communicates with a non-ground station; a plurality of ground relay stations that receive signals transmitted from the first ground station via the non-ground station and relay the signals to their destination via an optical communication network; a switch in the optical network that switches the communication paths to which the plurality of ground relay stations are connected; and a control device, wherein the control device comprises: an acquisition step of acquiring correlation information correlated with the communication environment for a ground relay station among the plurality of ground relay stations that is communicating with the non-ground station; and an instruction step of instructing the ground relay station communicating with the non-ground station and the switch to switch when the control device needs to switch the ground relay station communicating with the non-ground station to another ground relay station.

5. A communication system comprising: a first ground station that communicates wirelessly with a non-ground station; a plurality of ground relay stations that receive signals transmitted from the first ground station via the non-ground station and relay the signals to their destination via an optical communication network; and a switch in the optical network that switches the communication paths to which the plurality of ground relay stations are connected, wherein the computer program causes the computer to execute: an acquisition step of acquiring correlation information that is correlated with the communication environment for a ground relay station among the plurality of ground relay stations that is communicating with the non-ground station; and an instruction step of instructing the ground relay station communicating with the non-ground station and the switch to switch when the control device needs to switch the ground relay station communicating with the non-ground station to another ground relay station.

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