Wireless communication system, wireless communication control method, and wireless communication control device

Abstract

This wireless communication system switches the connection destination of a terrestrial wireless station from a first node station to a second node station. When the terrestrial wireless station cannot establish a link to the second node station before a link to the first node station is interrupted, the terrestrial wireless station establish a link to an absolute node station. The absolute node station is so located as to be able to connect to the terrestrial wireless station in the entire communication area, and has a lower connection priority than the first node station and the second node station. Next, the terrestrial wireless station switches the connection destination thereof from the first node station to the absolute node station. Subsequently, the terrestrial wireless station, after a link to the second node station is established, switches the connection destination to the second node station. In this way, the connection destination of the terrestrial wireless station can be switched to a new node station without occurrence of interruption of communication.

Description

[Technical field]

[0001] The present invention relates to a wireless communication system, a wireless communication control method, and a wireless communication control device. [Background technology]

[0002] Research is being conducted on wireless communication systems in which terrestrial wireless stations (e.g., satellite terrestrial stations and terminal stations) and node stations (e.g., satellite relay stations and cellular base stations) communicate with each other. The terrestrial wireless stations perform a switching process to switch the node station to which they are connected as the local station or the node station moves, etc. If the communication line and control line (hereinafter referred to as the link) between the local station and the node station are disconnected during the switching process, the communication is interrupted and the throughput of the entire system decreases.

[0003] For this reason, it is desirable to implement a process for switching the connection destination to an optimal node station without interrupting communication. For example, Non-Patent Document 1 discusses handover in a satellite communication system. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Sekiguchi, Fujii, and Tanibayashi, “A Study on Handover in LTE-based Satellite-Aircraft Communications”, 2019 IEICE Communications Society Conference, B-3-28, September 2019 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem of node station switching processing in a satellite communication system will be described with reference to Figs.

[0006] In Fig. 8, a link 86 is established between a satellite ground station 81 and a satellite repeater station 83. The satellite repeater stations 83, 84, and 85 are non-geostationary satellites, and move from right to left in Fig. 1. The satellite repeater station 83 moves away from the satellite ground station 81, while the satellite repeater station 84 moves closer to the satellite ground station 81. Before the link 86 is cut off and communication with the currently communicating satellite repeater station 83 is cut off, the satellite ground station 81 establishes a link 87 with a new satellite repeater station 84 and switches the communication route. This maintains communication between the satellite ground station 81 and the terminal station 82.

[0007] This node station switching process is based on the premise that the node stations (satellite relay stations 83, 84, 85) are densely arranged and that the terrestrial radio stations (satellite terrestrial station 81, terminal station 82) are able to establish links with new node stations before communication with the currently communicating node stations is cut off.

[0008] However, in reality, node stations are not always densely arranged due to reasons such as when a service is first launched or high costs. In the example shown in Fig. 9, the distance between the currently communicating node station (satellite relay station 83) and the new node station (satellite relay station 85) is large. Therefore, the satellite earth station 81 cannot establish a link 88 with the new node station before communication with the currently communicating node station is cut off. As a result, communication is cut off and the throughput of the entire system decreases.

[0009] The present invention has been made to solve the above-mentioned problems, and aims to provide a wireless communication system, a wireless communication control method, and a wireless communication control device that can switch the connection of a terrestrial radio station to a new node station without causing a communication interruption. [Means for solving the problem]

[0010] The first aspect relates to a wireless communication system. The wireless communication system includes a terrestrial wireless station, a first node station, a second node station, and an absolute node station. Terrestrial radio stations are located within the communication area. The first node station is connectable to the terrestrial radio station in a portion of the communication area. The second node station is connectable to the terrestrial radio station in a portion of the communication area. The absolute node station is arranged so as to be connectable to the terrestrial radio station throughout the communication area, and has a lower connection priority than the first node station and the second node station. When the terrestrial radio station is about to switch its connection from the first node station to the second node station, it cuts off the link with the first node station. Fixed time If a link with the second node station cannot be established before, a link with the absolute node station is established. Next, the terrestrial radio station switches the connection destination from the first node station to the absolute node station. Next, after a link with the second node station is established, the terrestrial radio station switches the connection destination to the second node station.

[0011] The second aspect relates to a wireless communication control method for switching a connection destination of a terrestrial radio station from a first node station to a second node station. Terrestrial radio stations are located within the communication area. The first node station is connectable to the terrestrial radio station in a portion of the communication area. The second node station is connectable to the terrestrial radio station in a portion of the communication area. The wireless communication control method includes a first step, a second step, and a third step. The first step is to cut off a link between the ground radio station and the first node station. Fixed time When a link between the terrestrial radio station and the second node station cannot be established before, a link between the terrestrial radio station and the absolute node station is established. The absolute node station is arranged to be connectable to the terrestrial radio stations throughout the communication area, and has a lower connection priority than the first node station and the second node station. In a second step, the connection destination is switched from the first node station to the absolute node station. In a third step, after a link between the terrestrial radio station and the second node station is established, the connection destination is switched to the second node station.

[0012] The third aspect relates to a radio communication control device for switching a connection destination of a terrestrial radio station from a first node station to a second node station. Terrestrial radio stations are located within the communication area. The first node station is connectable to the terrestrial radio station in a portion of the communication area. The second node station is connectable to the terrestrial radio station in a portion of the communication area. The wireless communication control device cuts off the link between the ground wireless station and the first node station. Fixed time If a link between the ground radio station and the second node station cannot be established before, a link between the ground radio station and the absolute node station is established. The absolute node station is arranged to be connectable to the terrestrial radio stations throughout the communication area, and has a lower connection priority than the first node station and the second node station. Next, the wireless communication control device switches the connection destination from the first node station to the absolute node station. Next, after a link between the terrestrial radio station and the second node station is established, the radio communication control device switches the connection destination to the second node station. Effect of the Invention

[0013] According to the present invention, an absolute node station that can always establish a link with a terrestrial radio station is deployed. When a terrestrial radio station switches its connection destination from a node station with which it is currently communicating to a new node station, it is possible to temporarily switch the connection destination to the absolute node station and prevent communication interruption. After that, after a link is established with a new node station with a higher connection priority, it is possible to switch the connection destination to the new node station. Therefore, according to the present invention, it is possible to switch the connection destination of a terrestrial radio station to a new node station without causing communication interruption, and it is possible to improve the throughput of the entire system. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a conceptual diagram for explaining an overview of a wireless communication system according to a first embodiment of the present invention. [Diagram 2] 1 is a diagram for explaining a communication route switching procedure in a wireless communication system according to a first embodiment of the present invention. [Diagram 3] 11 is a flowchart illustrating a communication route switching process in a terrestrial radio station. [Figure 4] FIG. 11 is a conceptual diagram for explaining an overview of a wireless communication system according to a second embodiment of the present invention. [Diagram 5] FIG. 11 is a diagram illustrating a communication route switching procedure in a wireless communication system according to a second embodiment of the present invention. [Figure 6] FIG. 2 is a block diagram illustrating an example of an overview of functions possessed by a terrestrial radio station. [Figure 7] FIG. 2 is a diagram illustrating an example of a hardware configuration of a wireless communication control device. [Figure 8] FIG. 1 is a diagram for explaining a problem with node station switching processing in a satellite communication system. [Figure 9] FIG. 1 is a diagram for explaining a problem with node station switching processing in a satellite communication system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. However, when the number, quantity, amount, range, etc. of each element is mentioned in the embodiments shown below, the present invention is not limited to the mentioned number unless it is specifically stated or clearly specified in principle. Furthermore, the structures, etc. described in the embodiments shown below are not necessarily essential to the present invention unless it is specifically stated or clearly specified in principle. Elements common to each figure are given the same reference numerals and duplicated explanations are omitted.

[0016] Embodiment 1 (1) Wireless communication system 1 is a conceptual diagram for explaining an overview of a wireless communication system according to embodiment 1. The wireless communication system shown in FIG. 1 is a satellite communication system including a plurality of terrestrial wireless stations 1, a plurality of node stations 2, and an absolute node station 3.

[0017] The absolute node station 3 is arranged so as to be able to wirelessly connect to all terrestrial radio stations 1 throughout its communication area. The absolute node station 3 according to the first embodiment is a geostationary satellite. Since a geostationary satellite orbits with the same period as the rotation period of the Earth, the relative distance between the absolute node station 3 and the terrestrial radio station 1 hardly changes. Therefore, the absolute node station 3 can always establish a link with the terrestrial radio station 1. Moreover, the absolute node station 3 is a satellite relay station, and is able to wirelessly connect to each of the multiple node stations 2.

[0018] The node station 2 is a non-geostationary satellite (mobile satellite) that has a lower altitude than a geostationary satellite. The node station 2 is, for example, a low earth orbit satellite (LEO), a medium earth orbit satellite (MEO), or a high altitude pseudo satellite (HAPS). The node station 2 moves from right to left in Fig. 1, and the relative distance between the node station 2 and the terrestrial radio station 1 changes. The node station 2 is a satellite relay station, and Fig. 1 illustrates satellite relay stations 20, 21, and 22. The satellite relay stations 20, 21, and 22 can be wirelessly connected to each other. When the terrestrial radio station 1 is located within its own communication area (which is absolutely a part of the communication area of ​​the node station 3), the node station 2 can wirelessly connect to the terrestrial radio station 1. For example, the satellite relay station 21 can wirelessly connect to the satellite earth station 10 located within its own communication area. The satellite relay station 22 can wirelessly connect to the terminal station 12 located within its own communication area.

[0019] The terrestrial radio station 1 is located within the communication area of ​​the absolute node station 3. The terrestrial radio station 1 is a satellite ground station or a terminal station, and FIG. 1 illustrates a satellite ground station 10 and terminal stations 11 and 12. In a state in which a wireless link is established as shown in FIG. 1, the terminal station 11 can communicate with the terminal station 12 via the node station 2. The satellite ground station 10 can communicate with the terminal stations 11 and 12 via the node station 2.

[0020] 1, the absolute node station 3, which is a geostationary satellite, has a larger transmission delay than the node station 2, which is a non-geostationary satellite. Therefore, the connection priority between the terrestrial radio station 1 and the absolute node station 3 is set lower than the connection priority between the terrestrial radio station 1 and the node station 2.

[0021] (2) Overview of communication route switching process Fig. 2 is a diagram for explaining a procedure for switching a communication route in the wireless communication system according to embodiment 1. With reference to Fig. 2, a process for switching the connection destination of the satellite earth station 10 (terrestrial wireless station 1) from the satellite relay station 21 (first node station) to the satellite relay station 22 (second node station) will be explained.

[0022] 2A, the satellite earth station 10 is communicating with the terminal station 12 via satellite relay stations 21 and 22. A link between the satellite earth station 10 and the satellite relay station 21 has been established, and the connection destination of the satellite earth station 10 is set to the satellite relay station 21.

[0023] FIG. 2B shows a state a certain time before the link between the satellite earth station 10 and the satellite relay station 21 is cut off. Due to the movement of the satellite relay station 21, the relative distance between the satellite earth station 10 and the satellite relay station 21 increases. The satellite earth station 10 searches for a satellite to be the next connection destination from a certain time before communication with the currently communicating mobile satellite is cut off. For example, the satellite earth station 10 attempts to establish a link with the satellite relay station 22 (second node station) before the link with the satellite relay station 21 (first node station) is cut off. If the link between the satellite earth station 10 and the satellite relay station 22 cannot be established, the satellite earth station 10 establishes a link with the absolute node station 3. After that, the satellite earth station 10 switches the connection destination from the satellite relay station 21 (first node station) to the absolute node station 3.

[0024] As a result, the communication route is switched to a route that passes through the absolute node station 3 and the satellite relay station 22, and the communication state between the satellite earth station 10 and the terminal station 12 is maintained. In this way, if the only satellite with which the satellite earth station 10 could establish a link before the link was cut off was a geostationary satellite (absolute node station 3), the satellite earth station 10 maintains the communication state by connecting to the geostationary satellite and switching the communication route. As described above, the absolute node station 3 is a satellite relay station with a larger transmission delay and lower connection priority than the node station 2, but is temporarily used to maintain the communication state.

[0025] 2C shows a state in which the link between the satellite earth station 10 and the satellite relay station 21 is cut off. The satellite relay station 21 moves away from the satellite earth station 10, and the link between the satellite relay station 21 and the satellite earth station 10 is cut off. For a while after that, the satellite earth station 10 is in a state in which it cannot establish links with any stations other than the absolute node station 3.

[0026] Thereafter, the satellite relay station 22 approaches the satellite earth station 10, and a link can be established between the satellite earth station 10 and the satellite relay station 22. After the link with the satellite relay station 22 (second node station) is established, the satellite earth station 10 switches the connection destination to the satellite relay station 22. By switching to the satellite relay station 22, which has a higher connection priority than the absolute node station 3, the communication quality is improved.

[0027] (3) Flowchart of communication route switching process 3 is a flow chart illustrating a communication route switching process in the terrestrial radio station 1. As described above, the terrestrial radio station 1 executes a communication route switching process for selecting a new node station to connect to and switching the communication route when a certain time before the link with the currently communicating node station is cut off. The communication route switching process is executed when a start process in another subroutine is established. The start conditions are based on the case where the radio wave intensity is equal to or less than a set value, the relative distance between the terrestrial radio station 1 and the currently communicating node station is equal to or more than a set value, a predetermined time has elapsed, the currently connected node station is an absolute node station, and the like. As an example, the initial state is a state in which the terrestrial radio station 1 (satellite ground station 10) and the first node station (satellite relay station 21) are connected to each other.

[0028] In step S100, it is determined whether there is another node station 2 (second node station) with which a link can be established without communication interruption. Whether a link can be established can be determined, for example, based on whether the radio wave intensity is above a threshold and the relative distance is below a threshold. If there is no second node station with which a link can be established, that is, if a link can be established only with the absolute node station 3, the process of step S110 is executed.

[0029] In step S110, the terrestrial radio station 1 (satellite ground station 10) establishes a link with the absolute node station 3. Next, the process of step S130 is executed.

[0030] In step S130, the terrestrial radio station 1 (satellite ground station 10) switches the connection destination from the first node station (satellite relay station 21) to the absolute node station 3. As a result, the communication route is switched from via the first node station (satellite relay station 21) to via the absolute node station 3. After that, this routine is ended.

[0031] By the process of step S130, the connection destination is switched to the absolute node station 3, and the communication route switching process is executed again in the next control period. Until the judgment condition of step S100 is satisfied, the communication route passing through the absolute node station 3 is adopted (steps S110, S130).

[0032] On the other hand, if a node station 2 capable of establishing a link is detected, the determination condition of step S100 is met. For example, if the relative distance between the second node station (satellite relay station 22) and the terrestrial radio station 1 (satellite terrestrial station 10) becomes small, the determination condition of step S100 is met. Next, the process of step S120 is executed.

[0033] In step S120, the terrestrial radio station 1 establishes a link with a node station 2 (second node station) that can establish a link without interrupting communication. For example, the terrestrial radio station 1 (satellite terrestrial station 10) establishes a link with a second node station (satellite relay station 22). Then, the process of step S130 is executed.

[0034] In step S130, the terrestrial radio station 1 (satellite ground station 10) switches the connection destination from the absolute node station 3 to the second node station (satellite relay station 22). The second node station has a higher connection priority (e.g., less transmission delay, higher radio wave strength) than the absolute node station 3. As a result, the communication route is switched from via the absolute node station 3 to via the second node station (satellite relay station 22). After that, this routine is terminated.

[0035] (4) Effects As described above, according to the system of this embodiment, an absolute node station 3 capable of establishing a link with a terrestrial radio station 1 is always deployed. When a terrestrial radio station switches its connection destination from a node station with which it is currently communicating to a new node station, it is possible to temporarily switch the connection destination to the absolute node station to prevent communication interruption. After that, after a link is established with a node station with a higher connection priority, it is possible to switch the connection destination to the new node station. Therefore, according to this embodiment, it is possible to switch the connection destination of a terrestrial radio station to a new node station without causing communication interruption, thereby improving the throughput of the entire system.

[0036] Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIGS.

[0037] (1) Wireless communication system Fig. 4 is a conceptual diagram for explaining an overview of a wireless communication system according to embodiment 2. The wireless communication system shown in Fig. 4 includes a plurality of terrestrial wireless stations 1, a plurality of node stations 2, and an absolute node station 3, similar to the wireless communication system according to embodiment 1.

[0038] The absolute node station 3 is arranged in the entire communication area so as to be able to wirelessly connect to all terrestrial radio stations 1. The absolute node station 3 is a cellular base station with a larger cell radius than the node station 2. The absolute node station 3 is connected to each of the multiple node stations 2 by wire.

[0039] The node station 2 is a cellular base station having a smaller cell radius than the absolute node station 3. In Fig. 4, cellular base stations 23 and 24 are illustrated. The cellular base stations 23 and 24 are connected to each other by wire. When the terrestrial wireless station 1 is located within its communication area (which is absolutely a part of the communication area of ​​the node station 3), the node station 2 can wirelessly connect to the terrestrial wireless station 1. For example, the cellular base station 23 can wirelessly connect to the terminal station 13 located within its communication area. The cellular base station 24 can wirelessly connect to the terminal station 14 located within its communication area.

[0040] The terrestrial radio station 1 is located within the communication area of ​​the absolute node station 3. Terminal stations 13 and 14 are illustrated in Fig. 4. In a state in which a wireless link is established as shown in Fig. 4, the terminal station 13 can communicate with the terminal station 14 via the node station 2.

[0041] The connection priority between the terrestrial radio station 1 and the absolute node station 3 is set lower than the connection priority between the terrestrial radio station 1 and the node station 2 .

[0042] (2) Overview of communication route switching process Fig. 5 is a diagram for explaining a procedure for switching a communication route in a wireless communication system according to embodiment 2. With reference to Fig. 5, a process for switching a connection destination of a terminal station 13 (terrestrial wireless station 1) from a cellular base station 23 (first node station) to a cellular base station 24 (second node station) will be explained.

[0043] 5A, the terminal station 13 is communicating with the terminal station 14 (not shown) via the cellular base stations 23 and 24, which have small cell radii. A link between the terminal station 13 and the cellular base station 23 is established, and the connection destination of the terminal station 13 is set to the cellular base station 23.

[0044] FIG. 5B shows a state a certain time before the link between the terminal station 13 and the cellular base station 23 is cut off. Due to the movement of the terminal station 13, the relative distance between the terminal station 13 and the cellular base station 23 becomes large. The terminal station 13 searches for a cellular base station to be the next connection destination from a certain time before communication with the cellular base station with which it is currently communicating is cut off. For example, the terminal station 13 tries to establish a link with the cellular base station 24 (second node station) before cutting off the link with the cellular base station 23 (first node station). If the link between the terminal station 13 and the cellular base station 24 cannot be established, the terminal station 13 establishes a link with the absolute node station 3. After that, the terminal station 13 switches the connection destination from the cellular base station 23 (first node station) to the absolute node station 3.

[0045] As a result, the communication route is switched to a route that passes through the absolute node station 3 and the cellular base station 24, and the communication state between the terminal station 13 and the terminal station 14 is maintained. In this way, if the only cellular base station with which the terminal station 13 could establish a link before the link was cut off was the absolute node station 3 with a large cell radius, the terminal station 13 maintains the communication state by connecting to the absolute node station 3 and switching the communication route. As described above, the absolute node station 3 is a cellular base station with a lower connection priority than the node station 2, but is used temporarily to maintain the communication state.

[0046] 5C shows a state in which the link between the terminal station 13 and the cellular base station 23 is cut off. The terminal station 13 moves away from the cellular base station 23, and the link between the terminal station 13 and the cellular base station 23 is cut off. For a while after that, the terminal station 13 is in a state in which it cannot establish links with any station other than the absolute node station 3.

[0047] Thereafter, the terminal station 13 approaches the cellular base station 24, and a link can be established between the terminal station 13 and the cellular base station 24. After the link with the cellular base station 24 (second node station) is established, the terminal station 13 switches the connection destination to the cellular base station 24. By switching to the satellite relay station 22, which has a higher connection priority than the absolute node station 3, the communication quality is improved.

[0048] (3) Flowchart of communication route switching process The flowchart of Fig. 3 described in the first embodiment is also applied to this embodiment. The above description of Fig. 3 is the same as that of the first embodiment, except that the example of the terrestrial radio station 1 is the terminal station 13, the example of the first node station is the cellular base station 23, and the example of the second node station is the cellular base station 24.

[0049] (4) Effects As described above, the system of this embodiment provides the same effects as those of embodiment 1. That is, according to this embodiment, the connection destination of a terrestrial radio station can be switched to a new node station without causing a communication interruption, and the throughput of the entire system can be improved.

[0050] (Hardware configuration example) FIG. 6 is a block diagram illustrating an outline of functions of the terrestrial radio station 1 according to each of the above-mentioned embodiments. The terrestrial radio station 1 includes a radio communication control device 40. The radio communication control device 40 includes a traffic control unit 41. The traffic control unit 41 performs the above-mentioned communication route switching process. The radio communication control device 40 includes a modem unit, an RF unit, and two antenna systems. The traffic control unit 41 may be built into the terrestrial radio station 1 or may be attached externally. The terrestrial radio station 1 may be equipped with multiple antennas, or may be equipped with one high-performance antenna.

[0051] 7 is a conceptual diagram showing an example of a hardware configuration of a processing circuit included in the traffic control unit 41 of the above-mentioned embodiment. Each of the above-mentioned functions is realized by the processing circuit. In one aspect, the processing circuit includes at least one processor 91 and at least one memory 92. In another aspect, the processing circuit includes at least one dedicated hardware 93.

[0052] When the processing circuit includes a processor 91 and a memory 92, each function is realized by software, firmware, or a combination of software and firmware. At least one of the software and firmware is written as a program. At least one of the software and firmware is stored in the memory 92. The processor 91 realizes each function by reading and executing the program stored in the memory 92.

[0053] Where the processing circuitry comprises dedicated hardware 93, the processing circuitry may be, for example, a single circuit, multiple circuits, a programmed processor, or a combination thereof. Each function is implemented by the processing circuitry.

[0054] Each function of the traffic control unit 41 may be partially or entirely configured by hardware, or may be configured as a program executed by a processor. That is, the traffic control unit 41 can be realized by a computer and a program, and the program can be recorded on a recording medium or provided through a network.

[0055] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and can be implemented in various modified forms without departing from the spirit of the present invention. [Explanation of symbols]

[0056] 1. Terrestrial radio station 2 Node Station 3 Absolute node station 10 Satellite ground station 11, 12, 13, 14 Terminal Station 20, 21, 22 Satellite relay stations 23, 24 Cellular base station 40 Wireless communication control device 41 Traffic Control Section 81 Satellite ground station 82 Terminal Station 83, 84, 85 Satellite relay stations 86, 87, 88 Links 91 Processor 92 Memory 93 Hardware

Claims

1. A terrestrial radio station located within the communication area; a first node station that is connectable to the terrestrial radio station in a part of the communication area; a second node station connectable to the terrestrial radio station in a part of the communication area; an absolute node station that is arranged so as to be connectable to the terrestrial radio stations throughout the communication area and has a lower connection priority than the first node station and the second node station; The terrestrial radio station includes: When switching the connection from the first node station to the second node station, If a link with the second node station cannot be established before a certain time period during which the link with the first node station is cut off, a link with the absolute node station is established; Switching the connection destination from the first node station to the absolute node station, After a link with the second node station is established, switching the connection destination to the second node station; A wireless communication system comprising:

2. the terrestrial radio station is a satellite terrestrial station or a terminal station; the absolute node station is a geostationary satellite; each of the first node station and the second node station is a non-geostationary satellite having an altitude lower than that of the geostationary satellite; 2. The wireless communication system according to claim 1,

3. the terrestrial radio station is a terminal station, Each of the first node station, the second node station and the absolute node station is a cellular base station; 2. The wireless communication system according to claim 1,

4. A wireless communication control method for switching a connection destination of a terrestrial wireless station from a first node station to a second node station, comprising: The terrestrial radio station is located within a communication area, the first node station is connectable to the terrestrial radio station in a part of the communication area; the second node station is connectable to the terrestrial radio station in a part of the communication area; The wireless communication control method includes: a first step of establishing a link between the terrestrial radio station and an absolute node station when a link between the terrestrial radio station and the second node station cannot be established before a certain time period during which the link between the terrestrial radio station and the first node station is cut off, the absolute node station being arranged so as to be connectable to the terrestrial radio station throughout the entire communication area and having a lower connection priority than the first node station and the second node station; a second step of switching the connection destination from the first node station to the absolute node station; a third step of switching the connection destination to the second node station after a link between the terrestrial radio station and the second node station is established; A wireless communication control method comprising:

5. the terrestrial radio station is a satellite terrestrial station or a terminal station; the absolute node station is a geostationary satellite; each of the first node station and the second node station is a non-geostationary satellite having an altitude lower than that of the geostationary satellite; 5. The wireless communication control method according to claim 4, further comprising:

6. the terrestrial radio station is a terminal station, Each of the first node station, the second node station and the absolute node station is a cellular base station; 5. The wireless communication control method according to claim 4, further comprising:

7. A wireless communication control device for switching a connection destination of a terrestrial wireless station from a first node station to a second node station, The terrestrial radio station is located within a communication area, the first node station is connectable to the terrestrial radio station in a part of the communication area; the second node station is connectable to the terrestrial radio station in a part of the communication area; The wireless communication control device includes: if a link between the terrestrial radio station and the second node station cannot be established before a certain time period during which the link between the terrestrial radio station and the first node station is cut off, a link between the terrestrial radio station and an absolute node station is established, the absolute node station being arranged so as to be connectable to the terrestrial radio station throughout the entire communication area and having a lower connection priority than the first node station and the second node station; Switching the connection destination from the first node station to the absolute node station, After a link between the terrestrial radio station and the second node station is established, switching the connection destination to the second node station; A wireless communication control device comprising:

8. the terrestrial radio station is a satellite terrestrial station or a terminal station; the absolute node station is a geostationary satellite; each of the first node station and the second node station is a non-geostationary satellite having an altitude lower than that of the geostationary satellite; 8. The wireless communication control device according to claim 7,

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