JP2017011341A - Ground base station, mobile terminal, communication system, and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground base station that can quickly concentrate the transmission capacity of satellite communication in an area where ground communication is unavailable if the area where ground communication is unavailable occurs.SOLUTION: A ground base station comprises: a communication mode determination processing unit 46 that determines whether the operation state of an adjacent ground base station is normal or not, sets a communication mode to a normal mode if the operation state of the adjacent base station is normal, and sets the communication mode to a disaster mode if the operation state of the adjacent base station is not normal; and a ground radio communication processing unit 42 that performs radio communication with a mobile terminal. If the communication mode is set to the disaster mode by the communication mode determination processing unit 46, the ground base station generates a response indicating the rejection of satellite communication and transmits it to a mobile terminal upon receiving a notice requesting permission of satellite communication from the mobile terminal.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a communication system capable of supporting both satellite communication and terrestrial communication, a terrestrial base station, a mobile terminal, and a communication method in the communication system.

  It is considered to provide services such as telephone calls using satellite communications in disaster areas where ground communication infrastructure such as ground base stations (hereinafter referred to as ground communication infrastructure) has been destroyed due to the occurrence of a major disaster. . Until now, many satellite communication services have been used only by some special users using devices dedicated to satellite communication, such as satellite mobile phones and modem devices for satellite communication. However, with the development of mobile terminal technology, mobile terminals such as smartphones and mobile phones that are used by many general users on a daily basis have both terrestrial wireless communication functions and satellite communication functions in accordance with standards such as LTE (Long Term Evolution). The terrestrial wireless communication function is usually used, but if the terrestrial communication infrastructure becomes unusable due to a disaster, it may be possible to switch to satellite communication and use services such as calls. It is considered.

  A conventional communication system that supports both satellite communication and terrestrial communication has two types of communication functions, satellite communication and terrestrial communication, and a mobile terminal that provides communication services such as calls using either one of the functions. And a ground base station that provides a communication service. The mobile terminal periodically transmits a control signal to the ground base station via a plurality of satellites at different positions. The ground base station calculates the current position of the mobile terminal from the time required for transmission of each control signal, and determines the communication type to be used, that is, satellite communication or ground communication, for the ground communication radio wave corresponding to the current position of the mobile terminal. Determined from the status and congestion status, etc., and instructed by satellite communication. The mobile terminal communicates with the communication method instructed by the base station. For this reason, the mobile terminal can receive a communication service by an appropriate communication method at the current position. For example, see Patent Document 1.

JP-A-5-300061

  In the above conventional communication system, the base station implements a control signal for acquiring the position of the mobile station and designating a communication method to be used by satellite communication. For this reason, there has been a problem that the transmission capacity of satellite communication to be allocated to a mobile terminal in an area where only satellite communication can be used due to a disaster is consumed by communication in another area, that is, an area where ground communication can be performed.

  In addition, in order to be able to use satellite communication preferentially in a disaster area, it is necessary to change the setting from the operation management device etc. to the ground communication system by the operator's operation. As it cannot be used, there is a problem that it takes time to concentrate the resources of satellite communication in the disaster area.

  The present invention has been made in view of the above, and when an area where terrestrial communication becomes impossible occurs, the transmission capacity of satellite communication can be quickly concentrated on the area where terrestrial communication becomes impossible. The purpose is to obtain a terrestrial base station.

  In order to solve the above-described problems and achieve the object, the ground base station according to the present invention determines whether the operation state of the adjacent ground base station is normal, and the operation state of the adjacent base station is A wireless communication between the mobile terminal and a mode control unit that sets the communication mode to the first mode when normal and sets the communication mode to the second mode when the operation state of the adjacent base station is not normal And a wireless communication unit that performs communication. When the second mode is set by the mode control unit, the terrestrial base station according to the present invention receives a notification requesting permission for satellite communication from the mobile terminal via the wireless communication unit, and performs satellite communication. A communication control unit that generates a response indicating that permission is not allowed and transmits the response to the mobile terminal via the wireless communication unit.

  Advantageous Effects of Invention According to the present invention, when an area where terrestrial communication becomes impossible occurs, the transmission capacity of satellite communication can be quickly concentrated on the area where terrestrial communication becomes impossible.

The figure which shows the structural example of the communication system concerning Embodiment 1. FIG. The figure which shows the function structural example of the mobile terminal of Embodiment 1. The figure which shows the hardware structural example of the mobile terminal of Embodiment 1. FIG. The figure which shows the structural example of a control circuit The figure which shows the function structural example of the ground base station of Embodiment 1. FIG. The figure which shows an example of the format of the normal notification of Embodiment 1 at the time of using a UDP packet The figure which shows an example of the hardware constitutions of the ground base station of Embodiment 1 The figure which shows an example of the service area of the ground communication and satellite communication at the time of disaster occurrence of Embodiment 1 The figure which shows an example of the communication sequence at the time of normality of Embodiment 1, ie, when a disaster has not occurred A diagram showing an example of the arrangement of ground base stations and mobile terminals The figure which shows an example of a communication sequence when the function of a ground base station stops by the disaster etc. of Embodiment 1 The flowchart which shows an example of the communication mode setting process sequence based on the terrestrial radio control signal in the communication mode control processing part of Embodiment 1 The flowchart which shows an example of the setting process sequence at the time of the satellite communication start request reception in the communication mode control process part of Embodiment 1. The flowchart which shows an example of the process sequence in the communication control process part of Embodiment 1. The flowchart which shows an example of the process sequence in the communication mode determination process part of Embodiment 1. A flowchart showing an example of a processing procedure in the communication service processing unit of the first embodiment The figure which shows the example of arrangement | positioning of each service area in case all the terrestrial communication service areas in which the terrestrial communication service located in the satellite communication service area including a terrestrial communication loss | disconnection service area does not lose | disappear are used as a disaster surrounding ground communication service area The figure which shows an example of the service area of the ground communication at the time of disaster occurrence of Embodiment 2, and satellite communication The figure which shows an example of the communication sequence at the time of disaster occurrence of Embodiment 2 It is a figure which shows the example of arrangement | positioning of a ground base station and a mobile terminal. The flowchart which shows an example of the transmission processing procedure of the normal notification in the communication mode determination process part of Embodiment 2, and a disaster mode notification The flowchart which shows an example of the determination process procedure of the communication mode in the communication mode determination process part of Embodiment 2.

  Hereinafter, a ground base station, a mobile terminal, a communication system, and a communication method according to embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram of a configuration example of a communication system according to the first embodiment of the present invention. As shown in FIG. 1, the communication system of the present embodiment includes a mobile terminal 1, a communication satellite 2, a satellite base station 3, and terrestrial base stations 4-1 to 4-9. The satellite base station 3 and the ground base stations 4-1 to 4-9 are connected to the main network 7 and connected to the communication network 8 via the main network 7. In FIG. 1, nine terrestrial base stations are illustrated, but the number of terrestrial base stations is not limited to the illustrated example, and may be any number. 1 shows one mobile terminal, the number of mobile terminals is not limited to the illustrated example and may be any number. When the ground base stations 4-2 to 4-9 are shown without distinction, they are appropriately described as the ground base stations 4.

  The mobile terminal 1 has two wireless communication functions, a satellite communication function and a ground communication function according to a communication standard such as LTE, and selects one of them to perform communication such as a call.

  The communication satellite 2 is an artificial satellite capable of forming one or more transmission / reception beams. Satellite communication service areas 5-1 and 5-2 in FIG. 1 are terrestrial areas irradiated by each transmission / reception beam when the communication satellite forms two transmission / reception beams, and the mobile terminal performs satellite communication using each transmission / reception beam. It is an area where it can be done. The communication satellite 2 relays communication between the mobile terminal located in the satellite communication service areas 5-1 and 5-2 and the satellite base station 3. Although FIG. 1 shows a case where there are two transmission / reception beams, the number of transmission / reception beams is not limited to the illustrated example, and may be any number. In FIG. 1, terrestrial base stations 4-1 to 4-4 exist in the satellite communication service area 5-1, and terrestrial base stations 4-5 to 4-9 exist in the satellite communication service area 5-2. However, the number of terrestrial base stations present in each satellite communication service area is not limited to the illustrated example.

  The satellite base station 3 is a base station in satellite communication, and relays communication data transmitted from the mobile terminal 1 received via the communication satellite 2 to the communication network 8. Further, the satellite base station 3 transmits communication data addressed to the mobile terminal 1 received from the communication network 8 to the mobile terminal 1 via the communication satellite 2.

  The ground base stations 4-1 to 4-9 perform ground communication according to a communication standard such as LTE with the mobile terminal 1, and provide mobile communication services such as a call to the mobile terminal 1. . The ground base stations 4-1 to 4-9 each have a service area that can provide a mobile communication service, that is, ground communication service areas 6-1 to 6-9, and each of the ground communication service areas 6-1 to 6-6. Relay communication between the mobile terminal existing in -9 and the communication network 8 is performed. The ground communication service areas 6-1 to 6-9 are areas where the ground base stations 4-1 to 4-9 can perform ground communication with the mobile terminal 1 through wireless communication.

  The trunk network 7 is a communication network that connects the ground base stations 4-1 to 4-9, and the ground base stations 4-1 to 4-9 and the communication network 8 with wires such as optical cables. The communication network 8 is a wide area communication network such as a public switched telephone network or the Internet.

  FIG. 2 is a diagram illustrating a functional configuration example of the mobile terminal 1 according to the present embodiment. As shown in FIG. 2, the mobile terminal 1 includes a terrestrial radio antenna 11, a satellite radio antenna 12, a terrestrial radio communication processing unit 13, a satellite radio communication processing unit 14, a communication control processing unit 15, a communication mode control processing unit 16, and an application. The unit 17 is provided.

  The terrestrial radio antenna 11 is a terrestrial radio antenna used when performing radio communication with the ground base stations 4-1 to 4-9. The satellite radio antenna 12 is a satellite radio antenna used when performing satellite communication with the communication satellite 2. The terrestrial radio communication processing unit 13 which is the first communication unit communicates with the terrestrial base stations 4-1 to 4-9 via the terrestrial radio antenna 11 in accordance with a standard such as LTE. Processing such as processing is performed to perform wireless communication, that is, ground wireless communication. The terrestrial radio communication processing unit 13 receives the terrestrial radio control signal, which is a control signal for terrestrial communication, via the terrestrial radio antenna 11 and transfers it to the communication mode control processing unit 16.

  A satellite wireless communication processing unit 14 as a second communication unit performs processing such as communication protocol processing in satellite communication via the satellite wireless antenna 12 with the communication satellite 2 to perform satellite communication. The communication protocol process in the satellite communication is performed according to, for example, GMR-1 3G “GEO-Mobile Radio Interface Specifications (Release 3); Third Generation Satellite Packet Radio Service”. Communication protocol processing in satellite communication is not limited to this example. In accordance with an instruction from the communication mode control processing unit 16, the communication control processing unit 15 switches so that the communication of the application unit 17 is performed by either one of the terrestrial wireless communication processing unit 13 or the satellite wireless communication processing unit 14. Further, when receiving a satellite communication start request from the application unit 17, the communication control processing unit 15 notifies the communication mode control processing unit 16 of the satellite communication start request. That is, the communication control processing unit 15 is a selection unit that selects either communication by the terrestrial wireless communication processing unit 13 or communication by the satellite wireless communication processing unit 14.

  The communication mode control processing unit 16 manages the communication mode of the mobile terminal 1, and controls switching of communication processing by the communication control processing unit 15, that is, selection of communication processing, according to the communication mode. There are two types of communication modes in the mobile terminal 1: a ground mode and a satellite mode. The ground mode is a mode for performing ground communication, and the satellite mode is a mode for performing satellite communication. In the terrestrial mode, the communication mode control processing unit 16 generates a satellite communication permission request when notified of the satellite communication start request from the communication control processing unit 15, and generates the communication control processing unit 15 and the terrestrial wireless communication processing unit 13. And it transmits to the ground base station 4 via the ground radio antenna 11. The communication mode control processing unit 16 determines a communication mode based on a response to the satellite communication permission request, and notifies the communication control processing unit 15 of the determined communication mode. The communication mode control processing unit 16 sets the communication mode to the terrestrial mode when receiving the terrestrial radio control signal at a constant period. Further, the communication mode control processing unit 16 switches the communication mode to the satellite mode when the terrestrial radio control signal cannot be received within a certain period. In addition, when the communication mode control processing unit 16 transmits a satellite communication permission request and receives a response for permitting satellite communication in the ground mode, the communication mode control processing unit 16 switches the communication mode from the ground mode to the satellite mode. Details of switching of the communication mode in the mobile terminal 1 will be described later.

  When starting satellite communication in the ground mode, the communication mode control processing unit 16 transmits a notification requesting permission for satellite communication to the ground base station 4 via the ground wireless communication processing unit 13. The communication mode control processing unit 16 communicates with the communication control processing unit 15 by the satellite wireless communication processing unit 14 when receiving a response permitting satellite communication from the ground base station 4 via the terrestrial wireless communication processing unit 13. Instructs the communication control processing unit 15 to select communication by the terrestrial radio communication processing unit 13 when receiving a response not permitting satellite communication from the terrestrial base station 4 via the terrestrial radio communication processing unit 13 A communication mode control unit.

  The application unit 17 communicates with the communication network 8 by satellite wireless communication or terrestrial wireless communication, thereby executing application processing for realizing various services such as calling, electronic mail, or web page browsing. In addition, application processing performed by the application unit 17 may use either ground communication or satellite communication, processing for performing only satellite communication for reasons such as disaster prevention drills, and for reasons of communication speed such as video services. There are three types of processing that perform only ground communication. When executing processing for performing satellite communication, the application unit 17 sends a start request for satellite communication to the communication control processing unit 15. When performing processing for performing ground communication, the application unit 17 sends a ground communication start request to the communication control processing unit 15. When performing a process that may be either satellite communication or ground communication, the application unit 17 sends a communication start request without specifying a communication type to the communication control processing unit 15.

  FIG. 3 is a diagram illustrating a hardware configuration example of the mobile terminal 1 according to the present embodiment. As shown in FIG. 3, the mobile terminal 1 of the present embodiment includes antennas 101 and 102, communication processing circuits 103 and 104, and a processing circuit 105. The antenna 101 corresponds to the terrestrial radio antenna 11 in FIG. 2, and the antenna 102 corresponds to the satellite radio antenna 12 in FIG. The communication processing circuit 103 corresponds to the terrestrial wireless communication processing unit 13, and the communication processing circuit 104 corresponds to the satellite wireless communication processing unit 14. The processing circuit 105 corresponds to the communication control processing unit 15, the communication mode control processing unit 16, and the application unit 17.

  The communication processing circuit 103 and the communication processing circuit 104 are electronic circuits such as a dedicated communication interface circuit that performs corresponding communication processing. Even if the processing circuit 105 is dedicated hardware, a CPU (Central Processing Unit, a central processing unit, a processing unit, a processing unit, a microprocessor, a microcomputer, a processor, a DSP that executes a memory and a program stored in the memory (Also referred to as a “Digital Signal Processor”). Here, the memory is, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory, or an EEPROM (Electrically Erasable Memory). A volatile semiconductor memory, a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a DVD (Digital Versatile Disk), and the like are applicable.

  When the above processing circuit 105 is realized by dedicated hardware, these include, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA ( Field Programmable Gate Array), or a combination of these.

  When the processing circuit 105 is realized by a control circuit including a CPU, the control circuit is, for example, a control circuit 200 having a configuration shown in FIG. FIG. 4 is a diagram illustrating a configuration example of the control circuit 200. As shown in FIG. 4, the control circuit 200 is an input unit 201 that is a reception unit that receives data input from the outside, a processor 202 that is a CPU, a memory 203, and a transmission unit that transmits data to the outside. And an output unit 204. The input unit 201 is an interface circuit that receives data input from the outside of the control circuit 200 and applies the data to the processor 202, and the output unit 204 is an interface that transmits data from the processor 202 or the memory 203 to the outside of the control circuit 200. Circuit. When the processing circuit 105 is realized by the control circuit 200 shown in FIG. 4, the processor 202 corresponds to each process of the communication control processing unit 15, the communication mode control processing unit 16, and the application unit 17 stored in the memory 203. This is realized by reading and executing the program. The memory 203 is also used as a temporary memory in each process executed by the processor 202.

  In FIG. 3, the communication control processing unit 15, the communication mode control processing unit 16, and the application unit 17 are realized by one processing circuit 105. However, the communication control processing unit 15, the communication mode control processing unit 16 and the application unit are realized. 17 may be individually configured as a processing circuit. In this case, these processing circuits may be dedicated hardware, or may be realized by the control circuit 200 as shown in FIG. Two of the communication control processing unit 15, the communication mode control processing unit 16, and the application unit 17 may be realized by one control circuit 200.

  FIG. 5 is a diagram illustrating a functional configuration example of the ground base station 4-1 according to the present embodiment. The ground base stations 4-2 to 4-9 have the same configuration as that of the ground base station 4-1. Hereinafter, as shown in FIG. 5, the ground base station 4-1 includes the ground wireless antenna 41, the ground wireless communication processing unit 42, the communication service processing unit 43, the wired communication processing unit 44, the wired communication port 45, and a communication mode determination process. Part 46 is provided.

  The ground radio antenna 41 is a ground communication antenna for communicating with the mobile terminal 1 using ground radio. The terrestrial radio communication processing unit 42 performs processing such as communication protocol processing for terrestrial communication with the mobile terminal 1 according to a standard such as LTE via the terrestrial radio antenna 41. That is, the terrestrial wireless communication processing unit 42 is a wireless communication unit that performs wireless communication with the mobile terminal 1. The terrestrial radio communication processing unit 42 transmits a terrestrial radio control signal via the terrestrial radio antenna 41 at regular intervals. The ground radio control signal includes identification information for identifying the source ground base station 4. This terrestrial radio control signal is a broadcast signal including information used by the mobile terminal 1 for connection processing with its own device. For example, a signal in a downlink control channel (DCI (Downlink Control Information)) format in LTE is used. However, the format of the terrestrial radio control signal is not limited to this.

  The communication service processing unit 43 performs processing for relaying communication between the mobile terminal 1 and the communication network 8 via the trunk network 7. In addition, the communication service processing unit 43 acquires from the communication mode determination processing unit 46 in response to a satellite communication permission request for requesting permission for satellite communication of the mobile terminal 1 via the ground wireless antenna 41 and the ground wireless communication processing unit 42. The response according to the communication mode is generated and transmitted via the ground radio antenna 41 and the ground radio communication processing unit 42. For example, a communication partner device corresponding to the type of service enjoyed by the mobile terminal 1 is connected to the communication network 8. Alternatively, the communication network 8 includes a device that relays communication with a communication partner device of the mobile terminal 1. For example, when the service enjoyed by the mobile terminal 1 is a call with a fixed telephone, the communication partner device is connected to the communication network 8 which is a public telephone network. For example, when the service that the mobile terminal 1 enjoys is web page browsing, a web server that is a communication partner device is connected to the communication network 8 that is the Internet.

  The wired communication port 45 is a communication port for connecting the ground base station 4-1 to the trunk network 7. The wired communication processing unit 44 performs communication protocol processing for wired communication with other ground base stations 4-2 to 4-9 via the wired communication port 45 and the trunk network 7. That is, the wired communication processing unit 44 is a base station communication unit that performs communication between the ground base stations 4.

  The communication mode determination processing unit 46 transmits an operation state indicating whether or not the operation of the ground base station 4 is normal for each of one or more adjacent ground base stations 4 set in advance via the trunk network 7. It is determined by control communication, and the communication mode of the own device is determined based on the determined operation state. In the communication mode determination processing unit 46, the terrestrial base station 4 adjacent to the terrestrial communication service area 6 in the satellite communication service area 5 including the terrestrial communication service area 6 formed by the own apparatus, that is, the terrestrial base station 4 is preset. Yes. The terrestrial base station 4 to which the terrestrial communication service area 6 to be formed is adjacent is referred to as an adjacent terrestrial base station 4. In other words, in the present embodiment, the terrestrial base station 4 adjacent to the terrestrial base station 4 has the terrestrial communication service area 6 that is a service area that can communicate with the terrestrial base station 4 as the terrestrial communication service area of its own device. 6 is a ground base station 4 adjacent to 6. In the present embodiment, there are two communication modes, a normal mode and a disaster mode. The normal mode is a mode indicating that the ground communication function in the own device is normal and that the ground communication functions of one or more adjacent ground base stations 4 set in advance are normal. The disaster mode is a mode indicating that the ground communication function of the own apparatus is normal and the ground communication function of one or more adjacent ground base stations 4 set in advance is lost. In addition, the communication mode determination processing unit 46 transmits a normal notification at regular intervals to one or more adjacent ground base stations 4 set in advance via the wired communication processing unit 44 and the wired communication port 45. The normal notification includes the identification information of the destination ground base station 4, the identification information of the transmission source ground base station 4, and the identification information indicating the normal notification. As the normal notification, for example, a UDP (User Datagram Protocol) packet can be used. FIG. 6 is a diagram illustrating an example of a normal notification format when a UDP packet is used. In the example of FIG. 6, the normal notification includes a MAC (Media Access Control) header, an IP (Internet Protocol) header, a UDP header, a destination ground base station ID (Identifier: identification information), a source ground base station ID, and a code. . The code is information indicating the type of notification, and a value indicating normal notification is determined in advance, and a code storing a value indicating normal notification is a normal notification. In addition, for a disaster mode notification described later, a notification in the same format as the normal notification can be used. In this case, for example, a normal notification when the code is 0, and a disaster mode notification when the code is 1. The code value is determined in advance.

  The communication mode determination processing unit 46 generates a normal notification indicating normal operation periodically, that is, at a constant cycle, and transmits the normal notification to the adjacent ground base station 4 via the wired communication processing unit 44. When the normal notification is regularly received from the terrestrial base station 4 to be determined, it is determined that the operation state of the adjacent base station is normal.

  That is, the communication mode determination processing unit 46 determines whether or not the operation state of the adjacent ground base station 4 is normal, and sets the communication mode to the first mode when the operation state of the adjacent base station is normal. Is a mode control unit that sets the communication mode to the disaster mode that is the second mode when the operation state of the adjacent ground base station 4 is not normal. In addition, when the disaster mode is set by the communication mode determination processing unit 46, the communication service processing unit 43 receives a notification requesting permission for satellite communication from the mobile terminal 1 via the terrestrial wireless communication processing unit 42. It is a communication control unit that generates a response indicating that satellite communication is not permitted and transmits the response to the mobile terminal 1 via the ground wireless communication processing unit 42. In addition, when there are a plurality of adjacent ground base stations 4, the communication mode determination processing unit 46 determines whether or not the operation state of all the adjacent ground base stations 4 is normal, and all the adjacent base stations 4 The communication mode is set to the normal mode that is the first mode when the operation state is normal, and the communication mode is set to the second mode when the operation state of one or more adjacent ground base stations 4 is not normal. Set a certain disaster mode.

  FIG. 7 is a diagram illustrating an example of a hardware configuration of the ground base station 4-1 according to the present embodiment. The hardware configuration of the ground base stations 4-2 to 4-9 is the same as the hardware configuration of the ground base station 4-1. As illustrated in FIG. 7, the ground base station 4-1 includes an antenna 401, a communication processing circuit 402, a processing circuit 403, a communication processing circuit 404, and a port 405. The antenna 401 corresponds to the terrestrial radio antenna 41, and the communication processing circuit 402 corresponds to the terrestrial radio communication processing unit 42. The processing circuit 403 corresponds to the communication service processing unit 43 and the communication mode determination processing unit 46, the communication processing circuit 404 corresponds to the wired communication processing unit 44, and the port 405 corresponds to the wired communication port 45.

  The communication processing circuit 402 and the communication processing circuit 404 are electronic circuits such as a dedicated communication interface circuit that performs corresponding communication processing. The processing circuit 403 may be dedicated hardware or a control circuit including a memory and a CPU that executes a program stored in the memory.

  When the above processing circuit 403 is realized by dedicated hardware, these are, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. It is.

  When the processing circuit 403 is realized by a control circuit including a CPU, the control circuit is, for example, the control circuit 200 having the configuration shown in FIG. When the processing circuit 403 is realized by the control circuit 200 shown in FIG. 4, the processor 202 reads out the programs corresponding to the processes of the communication service processing unit 43 and the communication mode determination processing unit 46 stored in the memory 203. It is realized by executing. The memory 203 is also used as a temporary memory in each process executed by the processor 202.

  In FIG. 7, the communication service processing unit 43 and the communication mode determination processing unit 46 are realized by one processing circuit 105, but the communication service processing unit 43 and the communication mode determination processing unit 46 are individually configured as processing circuits. May be. In this case, each of these processing circuits may be dedicated hardware, or may be realized by the control circuit 200 as shown in FIG.

  Next, the communication mode when a disaster occurs according to this embodiment will be described. FIG. 8 is a diagram illustrating an example of a service area for ground communication and satellite communication when a disaster occurs according to the present embodiment. In FIG. 8, the satellite communication service area 5 is indicated by a dotted circle. In FIG. 8, the symbol of the satellite communication service area 5 is attached to one satellite communication service area 5, but all the circles described with the same dotted line indicate the satellite communication service area. The satellite communication service area 5 is an area where the mobile terminal 1 can perform satellite communication with each transmission / reception beam of the communication satellite 2 as in the satellite communication service areas 5-1 and 5-2 of FIG.

  In FIG. 8, the ground communication service area 6 is indicated by a solid circle. In FIG. 8, the reference numeral of the ground communication service area 6 is attached to one ground communication service area, but the circles indicated by the same solid line all indicate the ground communication service area. In addition, an area in the ground communication service area 6 in which the ground communication function in the ground base station 4 is lost due to a disaster or the like is shown as a ground communication loss service area 61. In FIG. 8, the reference symbol for the ground communication loss service area 61 is attached to one ground communication loss service area, but all the circles with the same hatching indicate the ground communication loss service area 61. Further, the terrestrial communication service area 6 adjacent to the terrestrial communication loss service area 61 and not losing the terrestrial communication function by the terrestrial base station is shown as a disaster peripheral terrestrial communication service area 62. In FIG. 8, the reference symbol of the disaster peripheral ground communication service area 62 is attached to one disaster peripheral ground communication service area 62, but all the circles with the same hatching indicate the disaster peripheral ground communication service area 62. In FIG. 8, the satellite communication service area 5 and the ground communication service area 6 are indicated by circles, but the actual shape of the service area is not limited to a circle.

  In the present embodiment, as shown in FIG. 8, the communication of the ground base station 4 that forms the ground communication service area 6 that is adjacent to the ground communication loss service area 61 and in which the ground communication function by the ground base station 4 is not lost. Set the mode to disaster mode. A disaster peripheral ground communication service area 62 in FIG. 8 is a ground communication service area formed by the ground base station 4 whose communication mode is set to the disaster mode. When starting the satellite communication, the mobile terminal 1 transmits a satellite communication permission request to the ground base station 4 forming the ground communication service area 6 in which the mobile terminal 1 is located. Then, when the ground base station 4 that has set the communication mode to the disaster mode receives a satellite communication permission request from the mobile terminal 1 in the ground communication service area 6 formed by itself, a response that does not permit satellite communication, that is, The satellite communication non-permission response is transmitted to the mobile terminal that has transmitted the satellite communication permission request. Further, when the mobile terminal 1 does not receive a terrestrial radio control signal from any terrestrial base station 4, the mobile terminal 1 shifts to a satellite mode for performing satellite communication. Thereby, the mobile terminal 1 located in the ground communication service area 6 where the ground communication function is not lost does not use the transmission capacity of the satellite communication, and is located in the ground communication service area 6 where the ground communication function is lost. The transmission capacity of satellite communication can be concentrated on the mobile terminal 1.

  Next, the operation of the present embodiment will be described. FIG. 9 is a diagram illustrating an example of a communication sequence when the present embodiment is normal, that is, when no disaster has occurred. FIG. 9 is based on the arrangement shown in FIG. FIG. 10 is a diagram illustrating an arrangement example of the ground base stations 4-1 and 4-2 and the mobile terminals 1-1 and 1-2. As shown in FIG. 10, the ground communication service areas 6-1 and 6-2 formed by the ground base stations 4-1 and 4-2 are adjacent to each other. As shown in FIG. 10, the mobile terminal 1-1 is located in the ground communication service area 6-1 and the mobile terminal 1-2 is located in the ground communication service area 6-2. The mobile terminals 1-1 and 1-2 are the mobile terminals 1 described with reference to FIGS. 1, 2, and 3.

  As shown in FIG. 9, the ground base station 4-1 transmits a ground radio control signal at regular intervals (step S1). Specifically, as described above, the terrestrial radio communication processing unit 42 transmits the terrestrial radio control signal at regular intervals via the terrestrial radio antenna 41. The ground base station 4-1 transmits a normality notification to one or more adjacent ground base stations 4 set in advance at regular intervals (step S2). Specifically, as described above, the communication mode determination processing unit 46 sends one or more adjacent ground bases that are set in advance at regular intervals via the wired communication processing unit 44 and the wired communication port 45. Transmit to station 4. The one or more adjacent ground base stations 4 set in advance to the ground base station 4-1 include the ground base station 4-2, and are adjacent to the ground base station 4-2 set in advance. It is assumed that one or more ground base stations 4 include a ground base station 4-1. The cycle for transmitting the terrestrial radio control signal and the cycle for transmitting the normal notification may be the same or different. Although communication between the terrestrial base stations 4 passes through the main network 7, the main network 7 is not shown in FIG.

  Similarly to the ground base station 4-1, the ground base station 4-2 transmits a normal notification to one or more adjacent ground base stations 4 set in advance at regular intervals (step S3). A signal is transmitted at regular intervals (step S4).

  Since the ground base station 4-1 has received the normal notification from the ground base station 4-2 at regular intervals, the communication mode is set to the normal mode. Since the ground base station 4-2 can receive the normal notification from the ground base station 4-1 at regular intervals, the communication mode is set to the normal mode. In addition, since the mobile terminals 1-1 and 1-2 can receive the terrestrial radio control signals from the terrestrial base stations 4-1 and 4-2, respectively, the communication mode is set to the terrestrial mode.

  For example, when the application unit 17 sends a communication start request for terrestrial communication or a communication start request that does not specify a communication type, the mobile terminal 1-1 transmits a terrestrial radio control signal received from the terrestrial base station 4-1. Based on this, ground communication connection processing is performed (step S5). Specifically, the ground radio communication processing unit 13 transmits a connection request to the ground base station 4-1 via the ground radio antenna 11, and the ground radio communication processing unit 42 of the ground base station 4-1 The connection request is received via the mobile terminal 1-1 and a response is transmitted to the mobile terminal 1-1. Thereafter, for example, processing such as position registration processing is performed between the terrestrial wireless communication processing unit 13 and the terrestrial wireless communication processing unit 42. The ground communication connection process is performed according to a ground communication protocol such as LTE.

  When the ground communication connection processing is completed, the mobile terminal 1-1 transmits communication data to the communication network 8 via the ground base station 4-1 (step S6), and the mobile terminal 1- 1 transmitted from the communication network 8 is transmitted. 1 is received via the ground base station 4-1 (step S7).

  Specifically, in step S6, for example, the terrestrial wireless communication processing unit 13 receives the communication data generated by the application unit 17 via the communication control processing unit 15, and the received communication data is transmitted to the terrestrial wireless antenna 11. To the ground base station 4-1. In the destination of communication data, identification information of a communication partner apparatus connected to the communication network 8 is stored. In the terrestrial base station 4-1, the terrestrial radio communication processing unit 42 receives the communication data via the terrestrial radio antenna 41 and passes it to the communication service processing unit 43. The communication service processing unit 43 passes the communication data received from the terrestrial wireless communication processing unit 42 to the wired communication processing unit 44, and the wired communication processing unit 44 transmits the communication data via the wired communication port 45 and the trunk network 7 to the communication network 8. Send to. In step S 7, when the wired communication processing unit 44 receives communication data addressed to the mobile terminal 1-1 from the communication network 8 via the wired communication port 45 and the trunk network 7, it passes the communication data to the communication service processing unit 43. The communication service processing unit 43 passes the communication data received from the wired communication processing unit 44 to the terrestrial wireless communication processing unit 42, and the terrestrial wireless communication processing unit 42 passes the communication data to the mobile terminal 1-1 via the terrestrial wireless antenna 11. Send.

  For example, when the application unit 17 sends out a satellite communication start request, the mobile terminal 1-2 transmits a satellite communication permission request to the ground base station 4-2 (step S8). Specifically, the terrestrial radio communication processing unit 13 generates a satellite communication permission request and transmits it to the terrestrial base station 4-2 through the terrestrial radio antenna 11.

  When the ground base station 4-2 receives the satellite communication permission request, since the communication mode is the normal mode, the ground base station 4-2 transmits a satellite communication permission response permitting the satellite communication to the mobile terminal 1-2 (step S9). Specifically, when the terrestrial radio communication processing unit 42 receives the satellite communication permission request via the terrestrial radio antenna 41, the terrestrial radio communication processing unit 42 passes the request to the communication service processing unit 43. The communication service processing unit 43 generates a satellite communication permission request and transmits it to the ground base station 4-2 through the satellite radio antenna 12.

  When the mobile terminal 1-2 receives the satellite communication permission response, the mobile terminal 1-2 starts the satellite communication connection process, and thereafter, the satellite communication connection process is performed between the mobile terminal 1-2 and the satellite base station 3 via the communication satellite 2. Performed (steps S10 and S11). Specifically, when the communication mode control processing unit 16 receives the satellite communication permission response via the terrestrial radio antenna 11, the terrestrial radio communication processing unit 13, and the communication control processing unit 15, the communication mode control processing unit 16 sets the satellite mode to the communication control processing unit 15. The communication control processing unit 15 instructs the satellite wireless communication processing unit 14 to start the satellite communication connection processing. The satellite radio communication processing unit 14 starts the satellite communication connection process based on an instruction from the communication control processing unit 15. For example, the satellite wireless communication processing unit 14 transmits a connection request for requesting satellite communication connection to the communication satellite 2 as a control signal as satellite communication connection processing. The control signal is transmitted using, for example, a predetermined frequency for the control signal. When receiving a connection request for requesting a satellite communication connection, the communication satellite 2 transfers it to the satellite base station 3. Upon receiving the connection request transferred by the communication satellite 2, the satellite base station 3 sends a control signal such as an authentication request for performing satellite communication to the mobile terminal 1-2 that is the connection request source via the communication satellite 2. And transmit to the mobile terminal 1-2. The satellite radio communication processing unit 14 of the mobile terminal 1-2 transmits a control signal in response to the control signal transmitted from the satellite base station 3 to the satellite base station 3 via the communication satellite 2. In this way, control signals are transmitted and received between the satellite base station 3 and the mobile terminal 1-2 as satellite communication connection processing. The frequency used by the mobile terminal 1-2 for transmission / reception of communication data is also determined by the satellite communication connection process.

  After the satellite communication connection processing, the mobile terminal 1-2 transmits communication data to the communication network 8 via the communication satellite 2 and the satellite base station 3 (step S12), and the mobile terminal 1 transmitted from the communication network 8 is transmitted. Communication data addressed to -1 is received via the satellite base station 3 and the communication satellite 2 (step S13). Specifically, the communication satellite 2 transfers the communication data transmitted from the mobile terminal 1 to the satellite base station 3, and the satellite base station 3 communicates the communication data received from the mobile terminal 1-2 via the communication satellite 2. Transfer to network 8. Further, the satellite base station 3 transmits the communication data addressed to the mobile terminal 1-2 received from the communication network 8 to the mobile terminal 1 via the communication satellite 2.

  Next, the operation when the function of the ground base station 4-2 is stopped due to a disaster or the like in the arrangement example shown in FIG. 10 will be described. FIG. 11 is a diagram illustrating an example of a communication sequence when the function of the ground base station 4-2 is stopped due to a disaster or the like according to the present embodiment.

  Similarly to the example of FIG. 9, the terrestrial base station 4-1 transmits a terrestrial radio control signal at regular intervals (step S1), and sends a normal notification to one or more adjacent terrestrial base stations 4 set in advance. Transmission is performed at regular intervals (step S2). Here, as in FIG. 9, one or more adjacent ground base stations 4 preset for the ground base station 4-1 include the ground base station 4-2. It is assumed that one or more adjacent ground base stations 4 preset to -2 include the ground base station 4-1.

  When the ground base station 4-2 stops functioning due to a disaster or the like (step S20), neither the ground radio control signal nor the normal notification is transmitted. For this reason, since the ground base station 4-1 does not receive a normal notification from the ground base station 4-2 during a certain time that is a time equal to or longer than a certain period, the ground base station 4-1 shifts to the disaster mode (step S21). Even in the disaster mode, the ground base station 4-1 transmits a normal notification at a constant cycle.

  On the other hand, since the mobile terminal 1-2 does not receive a terrestrial radio control signal from the terrestrial base station 4-2 during a certain time that is a time longer than a certain period, the mobile terminal 1-2 shifts to the satellite mode (step S22). When the mobile terminal 1-2 receives the satellite communication start request or the start request not specifying the communication type after the transition to the satellite mode, the satellite communication connection processing is performed in the same manner as in steps S10 and S11 of FIG. (Steps S23 and S24). Then, the mobile terminal 1-2 transmits the communication data to the communication network 8 via the communication satellite 2 and the satellite base station 3 (step S25), and the communication addressed to the mobile terminal 1-2 transmitted from the communication network 8 Data is received via the satellite base station 3 and the communication satellite 2 (step S26). Note that after shifting to the satellite mode, the ground communication start request by the application unit 17 is immediately stopped by the communication control processing unit 15.

  Further, the mobile terminal 1-1 is set to the ground mode similarly to the example of FIG. 9, and in this state, for example, the application unit 17 sends out a satellite communication start request as in step S8 of FIG. In such a case, a satellite communication permission request is transmitted to the ground base station 4-1 (step S27). Since the ground base station 4-1 is in the disaster mode, when receiving the satellite communication permission request from the mobile terminal 1-1, the ground base station 4-1 transmits a satellite communication non-permission response indicating that the satellite communication is not permitted to the mobile terminal 1-1. (Step S28). When the mobile terminal 1-1 receives the satellite communication non-permission response, the process of the application unit 17 that performs the satellite communication process is stopped.

  On the other hand, when the application unit 17 sends a ground communication start request or a start request not specifying a communication type, the ground communication connection process is performed with the ground base station 4-1 as in step S 5 of FIG. 9. Implement (step S29). When the ground communication connection processing is completed, the mobile terminal 1-1 transmits communication data to the communication network 8 via the ground base station 4-1 (step S30), and the mobile terminal 1- 1 transmitted from the communication network 8 is transmitted. 1 is received via the ground base station 4-1 (step S31).

  Next, details of the operation of the communication mode control processing unit 16 of the mobile terminal 1 will be described. FIG. 12 is a flowchart illustrating an example of a communication mode setting process procedure based on the terrestrial radio control signal in the communication mode control processing unit 16. The communication mode control processing unit 16 determines whether or not a terrestrial radio control signal has been received via the terrestrial radio antenna 11 and the terrestrial radio communication processing unit 13 (step S101). When the terrestrial radio control signal is received (step S101 Yes), the communication mode is set to the terrestrial mode (step S102).

  Next, the communication mode control processing unit 16 determines whether or not the terrestrial radio control signal has been received within a certain time, that is, within a certain time after receiving the previous terrestrial radio control signal (step S103). The predetermined time is set to a value equal to or longer than a predetermined period in which the terrestrial radio control signal is transmitted.

  If the communication mode control processing unit 16 has not received a terrestrial radio control signal within a certain time (No at Step S103), the communication mode control processing unit 16 sets the communication mode to the satellite mode (Step S104), and returns to Step S101. If the terrestrial radio control signal is not received in step S101 (step S101), it is determined whether or not a predetermined time has elapsed since the previous terrestrial radio control signal was received (step S105). If the predetermined time has elapsed (step S105 Yes), the process proceeds to step S104. If the predetermined time has not elapsed (No at step S105), the process returns to step S101.

  In step S103, when a terrestrial radio control signal is received within a predetermined time (step S103 Yes), step S103 is repeated.

  FIG. 13 is a flowchart illustrating an example of a setting process procedure when the communication mode control processing unit 16 receives a start request for satellite communication. When receiving a satellite communication start request from the communication control processing unit 15 in the ground mode, the communication mode control processing unit 16 starts the process of FIG. In the terrestrial mode, there is a terrestrial base station 4 in which the mobile terminal 1 can receive a terrestrial radio control signal at a constant period. The communication mode control processing unit 16 sends a satellite communication permission request to the terrestrial base station 4 that can receive the terrestrial radio control signal at a constant cycle via the communication control processing unit 15, the terrestrial radio communication processing unit 13, and the terrestrial radio antenna 11. Transmit (step S106). Then, the communication mode control processing unit 16 determines whether the response received from the ground base station 4 via the ground radio antenna 11, the ground radio communication processing unit 13, and the communication control processing unit 15 is a satellite communication permission response ( Step S107). When the response received from the ground base station 4 is a satellite communication permission response (Yes in step S107), the communication control processing unit 15 is notified of the satellite mode (step S109a), and the process is terminated.

  If the response received from the ground base station 4 is not a satellite communication permission response (No in step S107), that is, if the response received from the ground base station 4 is a satellite communication non-permission response, the communication mode control processing unit 16 Without changing the communication mode, the communication control processing unit 15 is notified of the ground mode (step S109b), and the process ends.

  When the communication mode is set to the satellite mode by the above processing, the communication mode control processing unit 16 sets the communication mode to the ground mode when the communication corresponding to the satellite communication start request is completed.

  Next, details of the operation of the communication control processing unit 15 of the mobile terminal 1 will be described. FIG. 14 is a flowchart illustrating an example of a processing procedure in the communication control processing unit 15 according to the present embodiment. First, the communication control processing unit 15 determines whether or not a communication start request has been received from the application unit 17 (step S110). When the communication start request is not received from the application unit 17 (No at Step S110), Step S110 is repeated.

  When the communication start request is received from the application unit 17 (Yes in Step S110), the communication control processing unit 15 determines whether or not the communication mode is the satellite mode (Step S111). Specifically, the communication control processing unit 15 inquires of the communication mode control processing unit 16 about the communication mode, acquires the communication mode from the communication mode control processing unit 16, and determines whether or not the acquired communication mode is the satellite mode. to decide.

  When the communication mode is not the satellite mode, that is, when it is the terrestrial mode (No at Step S111), the communication control processing unit 15 determines whether or not the communication request from the application unit 17 is a satellite communication request (Step S112). . If the communication request from the application unit 17 is not a satellite communication request (No in step S112), the communication control processing unit 15 instructs the terrestrial radio communication processing unit 13 to perform the terrestrial communication connection process (step S113). When the ground communication connection process is completed, the communication control processing unit 15 controls to transmit / receive communication data via the ground wireless communication processing unit 13 (step S114). And the communication control process part 15 judges whether communication was complete | finished (step S115), and when communication is not complete | finished (step S115 No), repeats step S115. When the communication is finished (Yes in step S115), the process is finished.

  If the communication request from the application unit 17 is a satellite communication request in step S112 (Yes in step S112), the communication control processing unit 15 notifies the communication mode control processing unit 16 of a satellite communication start request (step S116). ). The communication control processing unit 15 determines whether or not the communication mode received from the communication mode control processing unit 16 as a response to this notification is the satellite mode (step S117). When the received communication mode is the satellite mode (step S117 Yes), the communication control processing unit 15 instructs the satellite wireless communication processing unit 14 to perform the satellite communication connection process (step S118). When the satellite communication connection process is completed, the communication control processing unit 15 controls to transmit / receive communication data via the satellite wireless communication processing unit 14 (step S119), and proceeds to step S115.

  If the communication mode is the satellite mode in step S111 (step S111 Yes), the communication control processing unit 15 determines whether the communication request from the application unit 17 is a ground communication request (step S120a). If it is not a ground communication request (No at Step S120a), the process proceeds to Step S118. When the request is a ground communication request (Yes at Step 120a), the communication control processing unit 15 notifies the application unit 17 of the failure to start communication (Step S120b) and ends the process. If the received mode is not the satellite mode in step S117 (No in step S117), the process proceeds to step S120b.

  Next, details of the operation of the communication mode determination processing unit 46 of the ground base station 4 of the present embodiment will be described. FIG. 15 is a flowchart illustrating an example of a processing procedure in the communication mode determination processing unit 46 according to the present embodiment. If there are a plurality of adjacent ground base stations 4 set in advance, the processing shown in FIG. 15 is performed for each adjacent ground base station 4. The communication mode determination processing unit 46 determines whether or not a normal notification has been received from the adjacent ground base station 4 (step S121). The adjacent ground base station 4 is one of the previously set adjacent ground base stations 4 described above.

  When a normal notification is received from the adjacent ground base station 4 (step S121 Yes), the communication mode determination processing unit 46 sets the communication mode to the normal mode (step S122). Then, the communication mode determination processing unit 46 determines whether or not the normal notification is received from the adjacent ground base station 4 within a predetermined time, that is, within a predetermined time after receiving the previous normal notification (step S123). ). This fixed time is set to a value equal to or longer than a fixed period in which the ground normality notification is transmitted.

  If the normal notification is received from the adjacent ground base station 4 within a certain time after the previous normal notification is received (Yes in step S123), step S123 is repeated. When the normal notification is not received from the adjacent ground base station 4 within a certain time after the previous normal notification is received (No in step S123), the communication mode determination processing unit 46 sets the communication mode to the disaster mode. (Step S124), the process returns to Step S121.

  In step S121, when a normal notification is not received from the adjacent ground base station 4 (No in step S121), it is determined whether or not a certain time has passed (step S125), and when a certain time has passed (step S125). Yes), the process proceeds to step S124. If the predetermined time has not elapsed (No at step S125), the process returns to step S121.

  Next, details of the operation of the communication service processing unit 43 of the ground base station 4 will be described. FIG. 16 is a flowchart illustrating an example of a processing procedure in the communication service processing unit 43. The communication service processing unit 43 determines whether or not a satellite communication permission request has been received from the mobile terminal 1 via the terrestrial wireless antenna 41 and the terrestrial wireless communication processing unit 42 (step S131). (Step S131 Yes), the communication mode determination processing unit 46 is inquired about the communication mode (Step S132). The communication service processing unit 43 determines whether or not the communication mode obtained by the inquiry is the normal mode (step S133). If the communication mode is the normal mode (step S133 Yes), the satellite communication permission response is processed by the terrestrial wireless communication process. The data is transmitted to the mobile terminal 1 via the unit 44 and the ground radio antenna 41 (step S134), and the process is terminated.

  If the normal mode is not set in step S133, that is, if the disaster mode is selected (No in step S133), the communication service processing unit 43 sends a satellite communication non-permission response to the mobile terminal 1 via the terrestrial radio communication processing unit 42 and the terrestrial radio antenna 41. (Step S135), and the process ends. If the satellite communication permission request is not received in step S131 (step S131 No), step S131 is repeated.

  As described above, in the present embodiment, when the terrestrial base station 4 becomes unable to receive a normal notification from another adjacent terrestrial base station 4 for a certain period of time, the adjacent terrestrial communication service area 6 becomes the terrestrial communication loss service area 61. By determining that it has become, and shifting to the disaster mode, its own ground communication service area 6 is set as the disaster peripheral ground communication service area 62. Then, by disabling the satellite communication of the mobile terminal 1 located in the disaster peripheral ground communication service area 62, the mobile terminal 1 uses the ground communication. Therefore, the resources of the same satellite communication service rear 5 are prevented from being consumed by the mobile terminal 1 located in the disaster peripheral ground communication service area 62 that can use the ground communication, and the ground communication is stopped. An effect is obtained that the mobile terminal 1 located in the lost service area 61 can use more satellite communication transmission capacity, that is, resources.

  Further, since the ground base station 4 performs control of permission or non-permission of satellite communication for the mobile terminal 1 using ground communication, a control signal for control of permission or non-permission of satellite communication is transmitted by satellite communication. The mobile terminal 1 located in the terrestrial communication loss service area 61 can use more satellite communication resources without consuming these resources.

  Further, the disaster peripheral ground communication service area 62 is automatically set when the ground communication loss service area 61 occurs. For this reason, normally, even in a location where terrestrial communication can be used, for example, the mobile terminal 1 that can use satellite communication for disaster drilling or the like, if it becomes the disaster peripheral terrestrial communication service area 62, satellite communication is automatically disabled. It can be permitted and it can be prevented that the mobile terminal 1 located in the disaster peripheral ground communication service area 62 that can use the ground communication service is consumed. Thereby, the effect that the mobile terminal 1 located in the ground communication loss | disconnection service area 61 in which the ground communication service has stopped can use more resources is acquired.

  In the present embodiment, satellite communication is not permitted for the mobile terminal 1 located in the disaster peripheral ground communication service area 62, but certain communication is not allowed to the mobile terminal 1 located in the disaster peripheral ground communication service area 62. A certain amount of satellite communication may be permitted. For example, communication of some mobile terminals 1 among the mobile terminals 1 located in the disaster peripheral ground communication service area 62 is permitted. Specifically, for example, if the number of mobile terminals 1 performing satellite communication is equal to or less than a certain number, a satellite communication permission response is returned when a satellite communication permission request is received. On the other hand, when the number of mobile terminals 1 performing satellite communication exceeds a certain number, when a satellite communication permission request is received, a satellite communication non-permission response is returned. In addition, when the mobile terminal 1 ends the satellite communication, the mobile terminal 1 transmits a satellite communication end notification to the ground base station 4. The terrestrial base station 4 manages the number Ns of mobile terminals 1 performing satellite communication, sets the initial value of Ns to 0, and increases Ns by 1 each time a satellite communication permission response is returned. Further, when receiving the satellite communication end notification, the ground base station 4 decreases Ns by one. Thereby, the ground base station 4 can manage the number Ns of the mobile terminals 1 performing satellite communication.

  In this embodiment, the satellite communication of all the mobile terminals 1 located in the disaster peripheral ground communication service area 62 cannot be used. However, priority is set according to the model of the mobile terminal 1 and the high priority terminal. For example, satellite communication may be used for terminals used in police and fire fighting. The mobile terminal 1 transmits the priority of its own terminal to the ground base station 4 together with the satellite communication permission request. Moreover, the mobile terminal 1 may set a priority for every communication. In this case, the mobile terminal 1 transmits the communication priority to the ground base station 4 together with the satellite communication permission request. When the disaster mode is set, when the communication service processing unit 43 receives the satellite communication permission request from the mobile terminal 1 together with the priority of the satellite wireless communication, the response indicating that the satellite communication is not permitted according to the priority or A response permitting satellite communication is generated and transmitted to the mobile terminal 1 via the terrestrial wireless communication processing unit 42. Specifically, for example, the priority is defined by two types of high priority and low priority. Then, when the priority received together with the satellite communication permission request is high priority, the communication service processing unit 43 generates a response for permitting satellite communication and transmits the response to the mobile terminal 1 together with the satellite communication permission request. If the received priority is low priority, a response not permitting satellite communication is generated and transmitted to the mobile terminal 1.

  In this embodiment, the normal notification between the ground base stations 4 is transmitted via the trunk network 7, but the normal notification may be transmitted by wireless communication.

  In the present embodiment, the terrestrial base stations 4 to which the terrestrial communication service areas 6 are adjacent are registered as adjacent to each other in the communication mode determination processing unit 46, but in the same satellite communication service area 5. All the ground base stations 4 in which the ground communication service area 6 is located may be registered in the respective communication mode determination processing units 46 as the adjacent ground base stations 4. That is, all the ground base stations 4 included in the irradiation range of the same beam of the communication satellite 2 are set as the above-described adjacent ground base stations set in advance. In this case, as shown in FIG. 17, all the terrestrial communication service areas 6 in which the terrestrial communication service is not lost, which are located in the satellite communication service area 5 including the terrestrial communication loss service area 61, are all located in the disaster peripheral terrestrial communication service area 62. It can be. FIG. 17 shows each service area when all the terrestrial communication service areas 6 that are located in the satellite communication service area 5 including the terrestrial communication lost service area 61 and in which the terrestrial communication service is not lost are designated as disaster peripheral terrestrial communication service areas 62. It is a figure which shows the example of arrangement | positioning. As described above, when all the ground communication service areas 6 in which the ground communication services located in the satellite communication service area 5 including the ground communication loss service area 61 are not lost are designated as the disaster peripheral ground communication service area 62, the ground communication loss service is obtained. Even when the satellite communication service area 5 is wider than the area 61, there is an effect that the satellite communication resource can be effectively used in the ground communication loss service area 61.

Embodiment 2. FIG.
Next, a communication system according to the second embodiment will be described. In the first embodiment, the terrestrial communication service area 6 of the terrestrial base station 4 adjacent to the terrestrial communication loss service area 61 is designated as the disaster peripheral terrestrial communication service area 62, and satellite communication is prohibited. In the present embodiment, the terrestrial communication service area 6 adjacent to the disaster peripheral terrestrial communication service area 62 is set as the disaster second peripheral terrestrial communication service area. Limit satellite communications.

  The configuration of the communication system of the present embodiment is the same as that of the first embodiment. The configurations of the ground base station 4 and the mobile terminal 1 of the present embodiment are the same as those of the first embodiment. Hereinafter, a different point from Embodiment 1 is demonstrated and the overlapping description is abbreviate | omitted.

  When the satellite communication service area 5 is wide, if the satellite communication is restricted not only in the ground communication service area 6 adjacent to the ground communication loss service area 61 but also in other ground communication service areas 6, the ground communication loss service area can be more effectively performed. 61 can be assigned satellite communication resources.

  FIG. 18 is a diagram illustrating an example of a service area for ground communication and satellite communication when a disaster occurs according to the present embodiment. 18, the satellite communication service area 5 and the ground communication service area 6 are the same as the example of FIG. 8 in the ground communication loss service area 61 and the disaster peripheral ground communication service area 62. In the present embodiment, the terrestrial communication service area 6 adjacent to the disaster peripheral terrestrial communication service area 62 and capable of normal ground communication is set as the disaster second peripheral terrestrial communication service area 63, and the disaster second peripheral terrestrial communication area 63 is set. The satellite communication of the mobile terminal 1 in the communication service area 63 is restricted.

  Since the operation of the present embodiment when it is normal, that is, when no disaster has occurred, is the same as that of the first embodiment, description thereof is omitted. FIG. 19 is a diagram illustrating an example of a communication sequence when a disaster occurs according to the present embodiment. In FIG. 19, the arrangement shown in FIG. 20 is assumed. FIG. 20 is a diagram illustrating an arrangement example of the ground base stations 4-1, 4-2, 4-3 and the mobile terminal 1-3. As shown in FIG. 20, the ground communication service area 6-1 formed by the ground base station 4-1 and the ground communication service area 6-2 formed by the ground base station 4-2 are adjacent to each other. The ground communication service area 6-1 and the ground communication service area 6-3 formed by the ground base station 4-3 are adjacent to each other. On the other hand, the ground communication service area 6-2 and the ground communication service area 6-3 are not adjacent to each other. The mobile terminal 1-3 is located in the ground communication service area 6-3. The mobile terminal 1-3 is the mobile terminal 1 described in FIG. 1, FIG. 2, and FIG.

  As shown in FIG. 19, as in the first embodiment, the ground base station 4-3 transmits a terrestrial radio control signal at regular intervals (step S41). A normal notification is transmitted to the adjacent ground base stations 4-2 and 4-3 set in advance at regular intervals (step S42). Similarly, the terrestrial base stations 4-2 and 4-3 also transmit normality notifications to the adjacent terrestrial base stations 4-1 set in advance at regular intervals (steps S43 and S44). The terrestrial base stations 4-2 and 4-3 also transmit terrestrial radio control signals at regular intervals. In FIG. 19, the terrestrial radio control signals transmitted from the terrestrial base stations 4-2 and 4-3 are The illustration is omitted. Although communication between the terrestrial base stations 4 passes through the trunk network 7, the trunk network 7 is not shown in FIG.

  Next, the ground base station 4-2 stops functioning due to a disaster or the like (step S45), and the normal notification is not transmitted from the ground base station 4-2. Since the ground base station 4-2 does not receive the normal notification within a predetermined time as in the first embodiment, the ground base station 4-2 shifts to the disaster mode (step S46).

  In the present embodiment, when the terrestrial base station 4-2 shifts to the disaster mode, a disaster mode notification is received instead of the normal notification to the adjacent terrestrial base station 4-3 that has received the normal notification. Are transmitted at regular intervals (step S47). As with the first embodiment, the normal notification is transmitted at regular intervals to the ground base station 4-1 in which the own device can no longer receive the normal notification.

  The ground base station 4-3 that has received the disaster mode notification shifts to the disaster second mode (step S48). The disaster second mode is a communication mode corresponding to the disaster second peripheral ground communication service area 63. The disaster second mode is a communication mode in which the ground base station 4-3 transmits a normal notification at a constant cycle, but returns a satellite communication non-permission response when receiving a satellite communication permission request from the mobile terminal 1-3. It is.

  Thereafter, the mobile terminal 1-3 transmits a satellite communication permission request to the terrestrial base station 4-3 in which the mobile terminal 1-3 can receive the terrestrial radio control signal at a constant cycle, similarly to the first embodiment (step S49). . Since the ground base station 4-3 is in the disaster second mode, when receiving the satellite communication permission request, the ground base station 4-3 transmits a satellite communication non-permission response to the mobile terminal 1-3 (step S50). Upon receiving the satellite communication non-permission response, the mobile terminal 1-3 stops the process in the case of an application that requires satellite communication.

  On the other hand, in the case of an application that may be terrestrial communication, terrestrial communication connection processing is performed with the terrestrial base station 4-3 in the same manner as in step S5 of FIG. When the ground communication connection process is completed, the mobile terminal 1-3 transmits communication data to the communication network 8 via the ground base station 4-3 (step S52), and the mobile terminal 1- 1 transmitted from the communication network 8 is transmitted. Communication data addressed to 3 is received via the ground base station 4-3 (step S53).

  As described above, in the present embodiment, when the communication mode determination processing unit 46 shifts from the normal mode that is the first mode to the second mode that is the disaster mode, the mode notification that notifies the transition to the disaster mode is notified. When the disaster mode notification is transmitted from the adjacent ground base station to the adjacent ground base station having the normal operation state via the wired communication processing unit 44 and the disaster mode notification is received from the adjacent ground base station. 3 is set to the disaster second mode. The disaster mode notification includes the identification information of the destination ground base station 4, the identification information of the transmission source ground base station 4, and the identification information indicating the overseas mode. Then, when the disaster second mode is set, the communication service processing unit 43, when receiving a notification requesting permission for satellite communication from the mobile terminal 1 via the ground wireless communication processing unit 42, does not permit the satellite communication. The response shown is generated and transmitted to the mobile terminal 1 via the terrestrial radio communication processing unit 42.

  Next, details of the operation of the communication mode determination processing unit 46 of the ground base station 4 of the present embodiment will be described. FIG. 21 is a flowchart illustrating an example of a transmission processing procedure of normal notification and disaster mode notification in the communication mode determination processing unit 46 of the present embodiment. In the first embodiment, the normal notification is transmitted at regular intervals regardless of the communication mode. However, in the present embodiment, the notification transmitted differs depending on the mode. As shown in FIG. 21, the communication mode determination processing unit 46 determines whether or not the communication mode is the disaster mode (step S141). When the communication mode is not the disaster mode, that is, when it is the normal mode or the disaster second mode (No in step S141), the communication mode determination processing unit 46 wired normal notification to all the adjacent ground base stations 4 set in advance. Transmission is performed via the communication processing unit 44 and the wired communication port 45 (step S142). Next, the communication mode determination processing unit 46 determines whether or not a certain period has elapsed, that is, whether or not a time corresponding to the certain period has elapsed (step S143), and when the certain period has elapsed (Yes in step S143). Return to step S141. If the fixed period has not elapsed (No at Step S143), Step S143 is repeated.

  If it is determined in step S141 that the communication mode is the disaster mode (Yes in step S141), the communication mode determination processing unit 46 sends a disaster mode notification to the adjacent ground base station 4 set in advance, respectively. And it transmits via the wired communication port 45 (step S144), and progresses to step S143.

  Next, communication mode determination processing in the communication mode determination processing unit 46 of the present embodiment will be described. FIG. 22 is a flowchart illustrating an example of a communication mode determination processing procedure in the communication mode determination processing unit 46 according to the present embodiment. First, the communication mode determination processing unit 46 determines whether either a disaster mode notification or a normal notification has been received (step S151). When either the disaster mode notification or the normal notification is received (step S151 Yes), it is determined whether the disaster mode notification or the normal notification is received from all the adjacent ground base stations 4 within a predetermined time (step S152). If any notification has been received from all adjacent ground base stations 4 (step S152 Yes), it is determined whether all notifications are normal notifications (step S153). When all the notifications are normal notifications (step S153 Yes), the communication mode is set to the normal mode (step S154). Then, it is determined whether or not a normal notification has been received from all adjacent ground base stations within a predetermined time (step S155), and if received (step S155 Yes), step S155 is repeated.

  If even one disaster mode notification has been received in step S153 (No in step S153), the communication mode determination processing unit 46 sets the communication mode to the disaster second mode (step S158), and returns to step S151. In step S152, when the disaster mode notification or the normal notification is not received within a certain time from one or more of the adjacent ground base stations 4 (No in step S152), the communication mode determination processing unit 46 sets the communication mode to the disaster mode. (Step S157), and the process returns to step S151. In step S151, when no notification is received from the adjacent ground base station (No in step S151), it is determined whether a certain time has elapsed since the last notification was received (step S156), and the certain time has elapsed. If not (No in step S156), the process returns to S151. If the predetermined time has passed (step S156 Yes), the process proceeds to step S157.

  As described above, the ground base station 4 that has detected that the adjacent ground base station 4 has stopped terrestrial communication by stopping the reception of the normal notification transmitted by the adjacent ground base station 4 The notification is transmitted to another normal adjacent ground base station 4. The ground base station 4 that has received the disaster mode notification does not permit the mobile terminal 1 to perform satellite communication. For this reason, the same effects as those of the first embodiment can be obtained, and the ground base station 4 adjacent to the ground communication loss service area 61 is set as the disaster peripheral ground communication service area 62 so that the satellite communication is not permitted. There is an effect that more satellite communication resources can be used as compared with the case where the satellite communication in the ground communication loss service area 61 is restricted.

  In the present embodiment, satellite communication is not permitted for the mobile terminal 1 located in the disaster peripheral ground communication service area 62, but certain communication is not allowed to the mobile terminal 1 located in the disaster peripheral ground communication service area 62. A certain amount of satellite communication may be permitted.

  In the present embodiment, the satellite communication of all mobile terminals 1 located in the disaster peripheral ground communication service area 62 cannot be used. As described in the first embodiment, however, Priorities may be provided so that satellite communication can be used for high priority terminals, such as terminals used in police and fire fighting. The mobile terminal 1 transmits the priority of its own terminal to the ground base station 4 together with the satellite communication permission request. Moreover, the mobile terminal 1 may set a priority for every communication. In this case, the mobile terminal 1 transmits the communication priority to the ground base station 4 together with the satellite communication permission request. When the disaster mode is set, when the communication service processing unit 43 receives the satellite communication permission request from the mobile terminal 1 together with the priority of the satellite wireless communication, the response indicating that the satellite communication is not permitted according to the priority or A response permitting satellite communication is generated and transmitted to the mobile terminal 1 via the terrestrial wireless communication processing unit 42. Specifically, for example, the priority is defined by two types of high priority and low priority. Then, when the priority received together with the satellite communication permission request is high priority, the communication service processing unit 43 generates a response for permitting satellite communication and transmits the response to the mobile terminal 1 together with the satellite communication permission request. If the received priority is low priority, a response not permitting satellite communication is generated and transmitted to the mobile terminal 1.

  In this embodiment, the normal notification and the disaster mode notification between the terrestrial base stations 4 are exchanged via the trunk network 7, but may be performed by wireless communication.

  In the present embodiment, the ground base station 4 that controls the disaster peripheral ground communication service area 62 transmits the disaster mode notification, so that the disaster second peripheral regional communication service area is located outside the disaster peripheral ground communication service area 62. 63 is set. In addition to this, the ground base station 4 that controls the disaster second surrounding area communication service area 63 transmits the disaster second mode notification, so that the disaster third surrounding area communication is further outside the disaster second surrounding area communication service area. It is also possible to set a service area, and to set the disaster third, fourth,... Surrounding area communication service area and restrict satellite communication of the mobile terminal 1 in all the disaster surrounding ground communication service areas. In this case, even when the satellite communication service area 5 is relatively large, the mobile terminal 1 in the ground communication loss service area 61 can use more satellite communication resources.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  1, 1-1 to 1-3 mobile terminals, 2 communication satellites, 3 satellite base stations, 4-1 to 4-9 terrestrial base stations, 5,5-1, 5-2 satellite communication service areas, 6,6- 1-6-9 Terrestrial communication service area, 7 trunk network, 8 communication network, 11 terrestrial radio antenna, 12 satellite radio antenna, 13 terrestrial radio communication processing unit, 14 satellite radio communication processing unit, 15 communication control processing unit, 16 communication Mode control processing unit, 17 application unit, 41 terrestrial radio antenna, 42 terrestrial radio communication processing unit, 43 communication service processing unit, 44 wired communication processing unit, 45 wired communication port, 46 communication mode determination unit, 101, 102, 401 antenna 103, 104, 402, 404 Communication processing circuit, 105, 403 processing circuit, 405 ports.

Claims (9)

It is determined whether the operation state of the adjacent ground base station is normal, and when the operation state of the adjacent base station is normal, the communication mode is set to the first mode, A mode control unit for setting the communication mode to the second mode when the operation state is not normal;
A wireless communication unit that performs wireless communication with a mobile terminal;
When the second mode is set by the mode control unit, when a notification requesting permission of satellite communication is received from the mobile terminal via the wireless communication unit, a response indicating that the satellite communication is not permitted A communication control unit that generates and transmits to the mobile terminal via the wireless communication unit;
A ground base station characterized by comprising:   2. The service area that is a range that can communicate with a ground base station is a ground base station that is adjacent to the service area that is a range that can communicate with its own device as the adjacent ground base station. Ground base station.   The terrestrial base station according to claim 1, wherein all the terrestrial base stations included in the same beam irradiation range of the communication satellite are the adjacent terrestrial base stations.   When the second mode is set by the mode control unit, the communication control unit receives a notification requesting permission for the satellite communication along with the communication priority from the mobile terminal via the wireless communication unit. Then, a response indicating that the satellite communication is not permitted or a response allowing the satellite communication is generated according to the priority and transmitted to the mobile terminal via the wireless communication unit. The ground base station according to 1, 2, or 3. A base station communication unit that performs communication between ground base stations,
With
The mode control unit periodically generates a normal notification indicating normal operation and transmits the normal notification to the adjacent ground base station via the base station communication unit, and periodically transmits the normal notification from the adjacent ground base station. The ground base station according to any one of claims 1 to 4, wherein when the normal notification is received, the operation state of the adjacent base station is determined to be normal. When the mode control unit shifts from the first mode to the second mode, the mode control unit notifies the adjacent ground base station whose operation state is normal to the mode notification that notifies the transition to the second mode. When transmitting via a base station communication unit and receiving a mode notification from an adjacent ground base station, the communication mode is set to the third mode,
When the third mode is set by the mode control unit, the communication control unit receives the notification requesting permission for satellite communication from the mobile terminal via the wireless communication unit, and performs the satellite communication. 6. The ground base station according to claim 5, wherein a response indicating that permission is not generated is generated and transmitted to the mobile terminal via the wireless communication unit. A first communication unit that performs radio communication with the ground base station according to any one of claims 1 to 6;
A second communication unit for performing satellite communication;
As a communication for transmitting and receiving communication data, a selection unit that selects one of communication by the first communication unit and communication by the second communication unit;
When starting satellite communication, a notification requesting permission for satellite communication is transmitted to the ground base station via the first communication unit, and satellite communication is performed from the ground base station via the first communication unit. When receiving a response that permits the communication, the selection unit is instructed to select communication by the second communication unit, and a response that does not permit the satellite communication from the ground base station via the first communication unit. A communication mode control unit that instructs the selection unit to select communication by the first communication unit when received,
A mobile terminal comprising: A communication satellite,
A ground base station according to any one of claims 1 to 6;
A mobile terminal according to claim 7;
A communication system comprising: A communication method in a communication system comprising a ground base station, and a mobile terminal comprising a first communication unit that performs wireless communication with the ground base station and a second communication unit that performs satellite communication,
The terrestrial base station determines whether the operation state of the adjacent ground base station is normal, and sets the communication mode to the first mode when the operation state of the adjacent base station is normal; A first step of setting the communication mode to a second mode when the operation state of the adjacent base station is not normal;
A second step of transmitting a notification requesting permission for satellite communication to the ground base station via the first communication unit when the mobile terminal starts satellite communication;
When the ground base station has set the second mode, upon receiving the notification from the mobile terminal, a response indicating that the satellite communication is not permitted is generated and transmitted to the mobile terminal, When the first mode is set, upon receiving the notification from the mobile terminal, a third step of generating a response indicating that satellite communication is permitted and transmitting the response to the mobile terminal;
When the mobile terminal receives a response permitting satellite communication from the ground base station, the mobile terminal performs communication by the second communication unit, and when the mobile terminal receives a response not permitting satellite communication from the ground base station, the first A fourth step of performing communication by one communication unit;
A communication method comprising:

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