Mobile satellite communication system, mobile satellite communication device, mobile satellite communication method, and mobile satellite communication program

Abstract

To provide a technique for managing the locations of user terminals that can improve the efficiency of a mobile satellite communication system.SOLUTION: A mobile satellite communication system includes a plurality of non-geostationary satellite devices, each of which includes communication means for communicating with a terrestrial user terminal and other non-geostationary satellite devices, and generation means for generating location information indicating an association between a user terminal connected to the non-geostationary satellite device and one of a plurality of geographical areas preset on the ground that corresponds to the location of the user terminal.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a satellite mobile communication system, a satellite mobile communication device, a satellite mobile communication method, and a satellite mobile communication program.

Background Art

[0002] In a general terrestrial mobile communication system, location information of a user terminal is managed based on which base station the user terminal is connected to, and communication between user terminals is realized using the location information of the user terminal.

[0003] Further, Patent Document 1 describes creating a virtual routing area (VRA) by developing a graph of associated / connected satellites at an arbitrary given time interval in a satellite mobile communication system.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a satellite mobile communication system using a satellite constellation, since a non-geostationary satellite serving as a relay station orbits the earth in a few hours, it moves much faster than the moving speed of a user terminal. Therefore, for example, the relay station to which the user terminal connects is updated every few minutes to ten-odd minutes. Therefore, when managing the location information of the user terminal as in the above-described terrestrial mobile communication system, the location information is updated every time the relay station to which the user terminal connects is updated. Therefore, frequent transmission and reception of management information occur, squeezing the communication bandwidth. Further, when communication is performed at the timing when the relay station is updated, a cache miss may occur in the transfer of communication data.

[0006] In addition, in the technology described in Patent Document 1, complicated processing is required to create a virtual routing area (VRA) for each given time interval.

[0007] The present disclosure has been made in view of the above problems, and an exemplary object thereof is to provide a technology for managing the location of a user terminal that can improve the efficiency of a satellite mobile communication system.

Means for Solving the Problems

[0008] A satellite mobile communication system device according to an exemplary aspect of the present disclosure includes a plurality of non-geostationary satellite devices. Each non-geostationary satellite device includes communication means for communicating with a user terminal on the ground and other non-geostationary satellite devices, a user terminal connected to the non-geostationary satellite device, and generation means for generating location information indicating an association between the user terminal and a geographical area corresponding to the location of the user terminal among a plurality of geographical areas preset on the ground.

[0009] A satellite mobile communication device according to an exemplary aspect of the present disclosure is a satellite mobile communication device included in a non-geostationary satellite device that constitutes a satellite mobile communication system including a plurality of non-geostationary satellite devices. The satellite mobile communication device includes communication means for communicating with a user terminal on the ground and other non-geostationary satellite devices, a user terminal connected to the satellite mobile communication device, and generation means for generating location information indicating an association between the user terminal and a geographical area corresponding to the location of the user terminal among a plurality of geographical areas preset on the ground.

[0010] A satellite mobile communication method according to an exemplary aspect of the present disclosure is a satellite mobile communication method by a satellite mobile communication system including a plurality of non-geostationary satellite devices. At least one processor included in each non-geostationary satellite device executes communication processing for communicating with a user terminal on the ground and other non-geostationary satellite devices, and generation processing for generating location information indicating an association between the user terminal connected to the non-geostationary satellite device and a geographical area corresponding to the location of the user terminal among a plurality of geographical areas preset on the ground.

[0011] A satellite mobile communication program according to an exemplary aspect of the present disclosure is a satellite mobile communication program for operating a computer as a satellite mobile communication device included in a non-geostationary satellite device that constitutes a satellite mobile communication system including a plurality of non-geostationary satellite devices. The computer is caused to function as communication means for communicating with a ground user terminal and other non-geostationary satellite devices, a user terminal connected to the satellite mobile communication device, and generation means for generating location information indicating an association between a geographical area corresponding to the location of the user terminal and a plurality of pre-set geographical areas on the ground.

Effect of the Invention

[0012] According to an exemplary aspect of the present disclosure, there is an exemplary effect that a location management technology for a user terminal capable of improving the efficiency of a satellite mobile communication system can be provided.

Brief Description of the Drawings

[0013]

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Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be exemplified. However, the present invention is not limited to the following exemplary embodiments, and various modifications are possible within the scope shown in the claims. For example, embodiments obtained by appropriately combining the technical means employed in the following exemplary embodiments may also be included in the scope of the present invention. Further, embodiments obtained by appropriately omitting a part of the technical means employed in the following exemplary embodiments may also be included in the scope of the present invention. Also, the effects mentioned in the following exemplary embodiments are merely examples of the effects expected in those exemplary embodiments, and do not define the extension of the present invention. That is, embodiments that do not exhibit the effects mentioned in the following exemplary embodiments may also be included in the scope of the present invention.

[0015] 〔First Exemplary Embodiment〕 A first exemplary embodiment, which is an example of an embodiment of the present invention, will be described in detail with reference to the drawings. This exemplary embodiment is a basic form of each of the exemplary embodiments described below. Note that the scope of application of each technical means adopted in this exemplary embodiment is not limited to this exemplary embodiment. That is, each technical means adopted in this exemplary embodiment can also be adopted in other exemplary embodiments included in the present disclosure as long as there are no particular technical obstacles. In addition, each technical means shown in the drawings referred to for explaining this exemplary embodiment can also be adopted in other exemplary embodiments included in the present disclosure as long as there are no particular technical obstacles.

[0016] (Configuration of Satellite Mobile Communication System) The configuration of the satellite mobile communication system 1 will be described with reference to FIG. 1. FIG. 1 is a block diagram showing the configuration of the satellite mobile communication system 1. As shown in FIG. 1, the satellite mobile communication system 1 includes a plurality of non-geostationary satellite devices 10. The plurality of non-geostationary satellite devices 10 each function as a relay station that communicates with a ground user terminal (not shown), and constitute a so-called satellite constellation.

[0017] In this specification, a non-geostationary satellite refers to a satellite orbiting an orbit other than the geostationary orbit. A non-geostationary satellite generally orbits at an altitude lower than the geostationary orbit, and its position as seen from the ground changes over time. In this specification, a satellite constellation refers to a system that operates a plurality of satellites in cooperation.

[0018] Each non-geostationary satellite device 10 includes communication means 110 for communicating with a ground user terminal and other non-geostationary satellite devices 10, and management means (generation means) 120 for generating and managing location information indicating the association between the user terminal connected to the non-geostationary satellite device 10 and the geographical area corresponding to the position of the user terminal among a plurality of preset geographical areas on the ground.

[0019] In this specification, a geographical area, also referred to as an area, is such that all terrestrial areas that can be connected while each non-geostationary satellite 10 orbits are pre-divided into a plurality of geographical areas. Note that for a certain area to be connectable from the non-geostationary satellite 10 means that the non-geostationary satellite 10 can be connected to a user terminal located in that area, and this area may also be referred to as the connectable range of the non-geostationary satellite 10. Although the size of one geographical area is not particularly limited, it may be the same size as the connectable range of one non-geostationary satellite 10. A geographical area is a fixed area and may be defined by, for example, latitude, longitude, etc.

[0020] Also, the communication between the non-geostationary satellite device 10 and the user terminal, and the communication between non-geostationary satellite devices 10 may be realized by any technology. For example, it may be communication by radio waves or communication by optical space communication.

[0021] (Effect of the satellite mobile communication system) As described above, in the satellite mobile communication system 1, each non-geostationary satellite device 10 is configured to generate location information indicating the association between the user terminal connected to the non-geostationary satellite device 10 and the geographical area corresponding to the position of the user terminal among a plurality of geographical areas preset on the ground.

[0022] Since such location information is not based on a relay station to which the user terminal is connected, unlike the above-described terrestrial mobile communication system, the location information is not updated every time the relay station to which the user terminal is connected is updated. Also, since the geographical area is fixed, there is no need to re-create the area at given time intervals as in the technology described in Patent Document 1. Therefore, according to the satellite mobile communication system 1, there is an effect that a location management technology for user terminals that can improve the efficiency of the satellite mobile communication system 1 can be provided.

[0023] (Configuration of the satellite mobile communication device) The configuration of the satellite mobile communication device 100 will be described with reference to FIG. 2. FIG. 2 is a block diagram showing the configuration of the satellite mobile communication device 100. As shown in FIG. 2, the satellite mobile communication device 100 is provided in the non-geostationary satellite device 10 and realizes the communication function of the non-geostationary satellite device 10. The non-geostationary satellite device 10 is one of a plurality of non-geostationary satellite devices 10 included in the satellite mobile communication system 1.

[0024] The satellite mobile communication device 100 includes communication means 110 for communicating with a ground user terminal and other non-geostationary satellite devices, a user terminal connected to the satellite mobile communication device, and management means (generation means) 120 for generating and managing location information indicating the association between the user terminal and a geographical area corresponding to the location of the user terminal among a plurality of pre-set geographical areas on the ground.

[0025] (Effect of satellite mobile communication device) As described above, in the satellite mobile communication device 100, a configuration is adopted in which location information indicating the association between the user terminal connected to the satellite mobile communication device 100 and the geographical area corresponding to the location of the user terminal among a plurality of pre-set geographical areas on the ground is generated. Therefore, according to the satellite mobile communication device 100, an effect can be obtained that a location management technology of the user terminal can be provided so that the satellite mobile communication system 1 constituted by the non-geostationary satellite device 10 equipped with the satellite mobile communication device 100 can be made more efficient.

[0026] 〔Second exemplary embodiment〕 A second exemplary embodiment, which is an example of an embodiment of the present invention, will be described in detail with reference to the drawings. For components having the same functions as those described in the above-described exemplary embodiments, the same reference numerals will be given, and the description thereof will be omitted as appropriate. Note that the scope of application of each technical means adopted in this exemplary embodiment is not limited to this exemplary embodiment. That is, each technical means adopted in this exemplary embodiment can be adopted in other exemplary embodiments included in the present disclosure as long as there are no particular technical obstacles. In addition, each technical means shown in each drawing referred to for explaining this exemplary embodiment can be adopted in other exemplary embodiments included in the present disclosure as long as there are no particular technical obstacles.

[0027] FIG. 3 is a diagram showing an overview of the satellite mobile communication system 1. In one aspect, the satellite mobile communication system 1 includes a plurality of non-geostationary satellite devices 10 orbiting the Earth in the same orbital plane. Note that the number of non-geostationary satellite devices included in the satellite mobile communication system 1 is not particularly limited, and for example, it can be 10 to 16, but it may be 9 or less, or 17 or more. In addition, the orbital planes of the non-geostationary satellite devices 10 included in the satellite mobile communication system 1 do not have to be the same, and the satellite mobile communication system 1 may include a plurality of non-geostationary satellite devices 10 having different orbital planes. As shown in FIG. 3, when distinguishing and representing each non-geostationary satellite device 10, it is denoted as non-geostationary satellite devices S1 to Sn.

[0028] In addition, in one aspect, the satellite mobile communication system 1 may include one or more terrestrial base stations BS. The terrestrial base station BS communicates with any one of the non-geostationary satellite devices 10 and may have a special function (for example, a user authentication function or the like). In addition, the satellite mobile communication system 1 may not include the terrestrial base station BS, and the functions of the terrestrial base station BS may be distributed and provided in each non-geostationary satellite device 10.

[0029] In one aspect, the communication between the non-geostationary satellite device 10 and the terrestrial base station BS may be managed such that the non-geostationary satellite device 10 that connects to the terrestrial base station BS based on time is managed, or the terrestrial base station BS may be managed by geographical area in the same manner as the user terminal UE, and the non-geostationary satellite device 10 that connects to the terrestrial base station BS based on the geographical area may be managed.

[0030] FIG. 3 also shows the connection status of the satellite mobile communication system 1 with the terrestrial user terminals UE (user terminals UE1 to UE3) and the terrestrial base station BS (terrestrial base station BS1) at a certain point in time. At the point in time shown in FIG. 3, the non-geostationary satellite device S1 is connected to the user terminal UE1 and the user terminal UE2. Note that the connection destination of the user terminal UE1 switches from the non-geostationary satellite device S1 to the non-geostationary satellite device S2 as the non-geostationary satellite devices 10 move. Also, at the point in time shown in FIG. 3, the terrestrial base station BS1 is connected to the non-geostationary satellite device Sn-1, but at different points in time, the terrestrial base station BS1 may be connected to other non-geostationary satellite devices 10.

[0031] Note that various methods such as time-based path control, dynamic path control such as OSPF, and other path controls can be applied to control the communication paths between the non-geostationary satellite devices 10 and between the non-geostationary satellite device 10 and the terrestrial base station BS.

[0032] FIG. 4 is a diagram showing an example of the relationship between the geographical area (area) and the connectable range of each non-geostationary satellite device 10. The vertical axis represents time, and time progresses from the upper part to the lower part. The horizontal axis represents the moving direction of each non-geostationary satellite device 10.

[0033] In the example shown in FIG. 4, areas 1 to n are preset as geographical areas. The size of each area is equal to the size of the connectable range of each non-geostationary satellite device 10.

[0034] At time t1, the connectable ranges of the non-geostationary satellite devices S1 to Sn coincide with areas 1 to n respectively. In other words, the number of geographical areas corresponding to the connectable range of each non-geostationary satellite device 10 is one. Also, the user terminals UE1 and UE2 located in area 1 are connected to the non-geostationary satellite device S1, and the user terminal UE3 located in area 6 is connected to the non-geostationary satellite device S6.

[0035] As time progresses to time t2, the connectable range of each non-geostationary satellite device 10 spans multiple areas. For example, the connectable range of the non-geostationary satellite device S1 corresponds to areas 1 and 12. Also, the connectable range of the non-geostationary satellite device S2 corresponds to areas 1 and 2. At this time, the number of geographical areas corresponding to the connectable range of each non-geostationary satellite device 10 becomes plural respectively. Also, the number of non-geostationary satellite devices 10 corresponding to one geographical area also becomes plural. Also, the connection destination of the user terminal UE1 located in area 1 switches to the non-geostationary satellite device S2, and the connection destination of the user terminal UE2 located in area 1 remains the non-geostationary satellite device S1. Also, the connection destination of the user terminal UE3 located in area 6 has switched to the non-geostationary satellite device S7.

[0036] Furthermore, as time progresses to time t3, the connectable range of each non-geostationary satellite device 10 coincides with each area again. For example, the connectable range of the non-geostationary satellite device S1 corresponds to area n. Also, the connectable range of the non-geostationary satellite device S2 corresponds to area 1. Also, the user terminals UE1 and UE2 located in area 1 are connected to the non-geostationary satellite device S2, and the user terminal UE3 located in area 6 is connected to the non-geostationary satellite device S7.

[0037] As described above, the connectable range of each non-geostationary satellite device 10 may be in one-to-one correspondence with a geographical area at each point in time, or the connectable ranges of a plurality of non-geostationary satellite devices 10 may correspond to one geographical area, or the connectable range of one non-geostationary satellite device 10 may correspond to a plurality of geographical areas, or they may be combined in any of these cases. Also, user terminals located in the same area may be connected to the same non-geostationary satellite device 10 or may be connected to different non-geostationary satellite devices 10.

[0038] FIG. 5 is a diagram showing a schematic configuration of the non-geostationary satellite device 10. The non-geostationary satellite device 10 in the present embodiment includes a satellite mobile communication device 100. The satellite mobile communication device 100 includes a communication means 110, a user terminal connection management means (generation means, information sharing means) 121, a user communication management means (sending means, transfer means) 130, a location information inquiry means (acquisition means) 140, an area address management means (specification means) 150, a user terminal management table T1, a location information management table T2, and an area address management table T3.

[0039] The communication means 110 executes communication with a ground user terminal UE, another non-geostationary satellite device 10, and a ground base station BS. When the satellite mobile communication system 1 does not include the ground base station BS, the communication means 110 executes communication between the ground user terminal UE and another non-geostationary satellite device 10. The communication means 110 may execute each communication with the user terminal UE, another non-geostationary satellite device 10, and the ground base station BS using the same communication method or different communication methods. Also, the communication means 110 for executing communication with the user terminal UE, the communication means 110 for executing communication with another non-geostationary satellite device 10, and the communication means 110 for executing communication with the ground base station BS may be provided separately.

[0040] The user terminal connection management means 121 processes connection requests from the user terminal UE. For example, in one aspect, when the terrestrial base station BS has a user authentication function, the user terminal connection management means 121 transmits the connection request from the user terminal UE to the terrestrial base station BS via another non-geostationary satellite device 10, and transmits the response from the terrestrial base station BS to the user terminal UE.

[0041] In addition, the user terminal connection management means 121 generates and manages location information indicating the association between the user terminal UE connected to the non-geostationary satellite device 10 and the geographical area corresponding to the location of the user terminal among a plurality of pre-set geographical areas on the ground.

[0042] Specifically, the connection request from the user terminal UE includes the location information of the user terminal UE. Based on the connection information, the user terminal connection management means 121 generates location information indicating the association between the user terminal UE attempting to connect to the non-geostationary satellite device 10 and the geographical area corresponding to the location of the user terminal UE, and transmits it to the terrestrial base station BS together with the connection request. Note that the identification information indicating the non-geostationary satellite device 10 may be associated with the location information. In addition, the user terminal connection management means 121 may store the generated location information in the user terminal management table T1.

[0043] When the response from the terrestrial base station BS is a connection permission for the user terminal UE, the user terminal connection management means 121 may transmit the location information of the user terminal UE connected to the non-geostationary satellite device 10 stored in the user terminal management table T1 to other non-geostationary satellite devices 10. In particular, the user terminal connection management means 121 may transmit the location information of the user terminal UE connected to the non-geostationary satellite device 10 to a neighboring non-geostationary satellite device 10. Another non-geostationary satellite device 10 that has received the location information of the user terminal UE stores the received location information in the location information management table T2 of the other non-geostationary satellite device 10. At this time, the identification information indicating the non-geostationary satellite device 10 to which the user terminal UE is connected may be associated with the location information of the user terminal UE stored in the location information management table T2.

[0044] In one aspect, the user terminal connection management means 121 may transmit the location information of the user terminal UE connected to the non-geostationary satellite device 10 to at least one of the first neighboring non-geostationary satellite device and the second neighboring non-geostationary satellite device. The first neighboring non-geostationary satellite device is a non-geostationary satellite device that includes the geographical area indicated by the location information within the connectable range. The second neighboring non-geostationary satellite device is a non-geostationary satellite device that includes the geographical area indicated by the location information within the next connectable range. Note that "including the geographical area within the next connectable range" means that the geographical area exists at a position adjacent to the connectable range of the non-geostationary satellite device in the moving direction of the non-geostationary satellite device and is included in the connectable range of the non-geostationary satellite device when the non-geostationary satellite device moves in the orbital plane.

[0045] In this way, by transmitting the location information of the user terminal UE connected to the non-geostationary satellite device 10 to other non-geostationary satellite devices 10, particularly neighboring non-geostationary satellite devices 10, the location information of the user terminal UE can be shared with other non-geostationary satellite devices 10, and the processing when the user terminal UE connects to other non-geostationary satellite devices 10 can proceed smoothly.

[0046] In particular, since the first neighboring non-geostationary satellite device 10 and the second neighboring non-geostationary satellite device 10 are highly likely to be connected to the user terminal UE, it is beneficial to share the location information of the user terminal UE. Also, in one aspect, as will be described later, in the satellite mobile communication system 1, the communication content addressed to a certain user terminal UE is transmitted to the non-geostationary satellite device 10 corresponding to the geographical area of the user terminal UE based on the geographical area of the user terminal UE. At this time, even when there are a plurality of non-geostationary satellite devices 10 corresponding to the geographical area, if the location information of the user terminal UE connected to the neighboring non-geostationary satellite device 10 is shared, the communication content can be quickly transmitted to the target user terminal UE.

[0047] In the above, the case where each non-geostationary satellite device 10 has the same orbital plane has been described. However, as described above, the satellite mobile communication system 1 may include a plurality of non-geostationary satellite devices 10 having different orbital planes. In this case, as the neighboring non-geostationary satellite device 10, the location information may be shared with the non-geostationary satellite device 10 having the same orbital plane. However, considering that the position of the non-geostationary satellite device 10 as viewed from the ground shifts due to the rotation of the earth, the location information may be shared with the non-geostationary satellite device 10 having a different orbital plane as the neighboring non-geostationary satellite device 10.

[0048] Also, in addition to the location information, the user terminal connection management means 121 may transmit information indicating the scheduled time when the geographical area corresponding to the connectable range of the non-geostationary satellite device 10 will change to other non-geostationary satellite devices 10. Thereby, when the geographical area corresponding to the connectable range of the non-geostationary satellite device 10 changes and the connection destination of the user terminal UE connected to the non-geostationary satellite device 10 switches to another non-geostationary satellite device 10, the processing can proceed more smoothly.

[0049] The user communication management means 130 manages the communication of the user terminal UE connected to the non-geostationary satellite device 10.

[0050] In one aspect, when the non-geostationary satellite device 10 receives communication content addressed to a specific user terminal UE from the user terminal UE connected to the non-geostationary satellite device 10, the user communication management means 130 transmits the communication content addressed to the specific user terminal UE to other non-geostationary satellite devices 10 in association with information identifying the geographical area corresponding to the location of the specific user terminal UE.

[0051] The information for identifying the geographical area is not particularly limited as long as it can identify the geographical area. For example, it may be an address corresponding to the geographical area.

[0052] The location information management table T2 stores location information indicating the association between the user terminal UE connected to other non-geostationary satellite devices 10 and the geographical area where the user terminal UE is located. The user communication management means 130 may refer to the location information management table T2 to obtain information for identifying the geographical area corresponding to the location of the specific user terminal UE.

[0053] Also, when the location information management table T2 does not include the location information of the specific user terminal UE, the location information inquiry means 140 may inquire about the location information of the specific user terminal UE and obtain the location information of the specific user terminal UE.

[0054] Specifically, first, the satellite mobile communication system 1 further includes a collecting means for collecting the location information managed by the user terminal connection management means 121 of each non-geostationary satellite device 10. In one aspect, the terrestrial base station BS functions as the collecting means. Then, the location information inquiry means 140 may obtain the location information of the specific user terminal UE directly from the terrestrial base station BS or via other non-geostationary satellite devices 10 from the terrestrial base station BS.

[0055] As a result, the user communication management means 130 can transmit the communication content addressed to a specific user terminal UE to another non-geostationary satellite device 10 in association with information identifying the geographical area corresponding to the location of the specific user terminal UE.

[0056] Also, when the non-geostationary satellite device 10 receives communication content associated with identification information identifying a geographical area from another non-geostationary satellite device 10, if the user communication management means 130 compares the geographical area indicated by the identification information with the geographical area corresponding to the connectable range of the non-geostationary satellite device 10 and they do not match, the communication content may be transferred to a non-geostationary satellite device 10 different from the other non-geostationary satellite device 10, and if they match, the communication content may be transmitted to the destination user terminal UE.

[0057] The geographical area corresponding to the connectable range of the non-geostationary satellite device 10 is specified, for example, by the area address management means 150. In one aspect, the area address management means 150 refers to an area address management table T3 showing the correspondence between the position of the non-geostationary satellite device 10 and the address indicating the geographical area, and automatically updates the address indicating the geographical area corresponding to the connectable range of the non-geostationary satellite device 10 based on the position of the non-geostationary satellite device 10.

[0058] In one aspect, the area address management table T3 may be a table showing the correspondence between the position of the non-geostationary satellite device 10 and the address identifying the geographical area, or may be one showing parameters for calculation for specifying the address indicating the geographical area from the position of the non-geostationary satellite device 10.

[0059] As a result, the user communication management means 130 can appropriately process the communication content received from another non-geostationary satellite device 10. If the communication content received from another non-geostationary satellite device 10 includes information on the source user terminal UE and information indicating the geographical area of the source user terminal UE, the user communication management means 130 may generate location information of the source user terminal UE based on these and store it in the location information management table T2.

[0060] In addition, the area address management means 150 may acquire the positions of neighboring non-geostationary satellite devices 10, and further automatically update the address indicating the geographical area corresponding to the connectable range of the neighboring non-geostationary satellite devices 10.

[0061] Subsequently, with reference to FIGS. 6 to 8, the operation of the satellite mobile communication system 1 will be described. FIGS. 6 to 8 are flowcharts showing an example of the operation of the satellite mobile communication system 1.

[0062] First, with reference to FIG. 6, the operations in which the user terminals UE1 and UE3 are connected to the non-geostationary satellite devices S1 and S6, respectively, will be described.

[0063] In step S100, the non-geostationary satellite device S1 transmits a reference signal (reference burst) within the connectable range. The user terminal UE1 that has received the reference signal from the non-geostationary satellite device S1 transmits a connection request to the non-geostationary satellite device S1 in step S102. At this time, the connection request includes the location information of the user terminal UE1.

[0064] In step S104, the user terminal connection management means 121 of the non-geostationary satellite device S1 generates the location information of the user terminal UE1 based on the connection request and stores it in the user terminal management table T1. FIG. 9 shows an example of the user terminal management table T1 in step S104.

[0065] In steps S106 to S108, the user terminal connection management means 121 of the non-geostationary satellite device S1 transmits the connection request and the location information of the user terminal UE1 to the terrestrial base station BS1 via the relay station (non-geostationary satellite device Sn).

[0066] In step S110, the terrestrial base station BS1 authenticates the connection of the user terminal UE1 based on the connection request of the user terminal UE1, and adds the location information of the user terminal UE1 to the user area management table of the terrestrial base station BS1. FIG. 10 shows an example of the user area management table in step S110.

[0067] Then, in steps S112 to S114, the terrestrial base station BS1 transmits the authentication result of the connection of the user terminal UE1 to the non-geostationary satellite device S1 via the relay station (non-geostationary satellite device Sn).

[0068] In step S116, the user terminal connection management means 121 of the non-geostationary satellite device S1 transmits the authentication result of the connection of the user terminal UE1 to the user terminal UE1. Also, in step S118, the user terminal connection management means 121 transmits the location information stored in the user terminal management table T1 to the neighboring non-geostationary satellite device S2. As a result, location information as shown in FIG. 9 is also stored in the user terminal management table T1 of the non-geostationary satellite device S2.

[0069] Also, in step S120, the non-geostationary satellite device S6 transmits a reference signal (reference burst) within the connectable range. The user terminal UE3 that has received the reference signal from the non-geostationary satellite device S6 transmits a connection request to the non-geostationary satellite device S6 in step S122. At this time, the connection request includes the location information of the user terminal UE3.

[0070] In step S124, the user terminal connection management means 121 of the non-geostationary satellite device S6 generates the location information of the user terminal UE3 based on the connection request and stores it in the user terminal management table T1.

[0071] In steps S126 to S130, the user terminal connection management means 121 of the non-geostationary satellite device S6 transmits the connection request and location information of the user terminal UE3 to the terrestrial base station BS1 via the relay station.

[0072] In step S132, the terrestrial base station BS1 authenticates the connection of the user terminal UE3 based on the connection request of the user terminal UE3, and adds the location information of the user terminal UE3 to the user area management table of the terrestrial base station BS1. FIG. 11 shows an example of the user area management table in step S132.

[0073] Then, in steps S134 to S138, the terrestrial base station BS1 transmits the authentication result of the connection of the user terminal UE3 to the non-geostationary satellite device S6 via the relay station.

[0074] In step S140, the user terminal connection management means 121 of the non-geostationary satellite device S6 transmits the authentication result of the connection of the user terminal UE3 to the user terminal UE3. Also, in step S142, the user terminal connection management means 121 transmits the location information stored in the user terminal management table T1 to a neighboring non-geostationary satellite device (not shown).

[0075] Subsequently, referring to FIG. 7, the operation in which the user terminals UE1 and UE3 communicate with each other will be described.

[0076] In step S200, the user terminal UE3 transmits the communication content addressed to the user terminal UE1 to the non-geostationary satellite device S6. FIG. 12 shows an example of the header information of the communication content addressed to the user terminal UE1.

[0077] In steps S202 to S206, the location information inquiry means 140 of the non-geostationary satellite device S6 inquires the terrestrial base station BS1 about the location information of the user terminal UE1 via the relay station.

[0078] In step S208, the terrestrial base station BS1 identifies the location information of the user terminal UE1 by referring to the user area management table as shown in FIG. 11. Then, in steps S210 to S214, the terrestrial base station BS1 transmits the location information of the user terminal UE1 to the non-geostationary satellite device S6 via the relay station.

[0079] Then, in S216, the user communication management means 130 of the non-geostationary satellite device S6 encapsulates the communication content addressed to the user terminal UE1 in association with the information (address of area 1) for identifying the geographical area corresponding to the position of the user terminal UE1 based on the location information of the user terminal UE1, and transmits it to the non-geostationary satellite device S1 via the relay station. FIG. 13 shows an example of the header information of the encapsulated communication content.

[0080] In step S218, the user communication management means 130 of the non-geostationary satellite device S1 decapsulates and transmits the communication content addressed to the user terminal UE1 to the user terminal UE1.

[0081] Also, in step S220, the user terminal UE1 transmits the communication content addressed to the user terminal UE3 to the non-geostationary satellite device S1. FIG. 14 shows an example of the header information of the communication content addressed to the user terminal UE3.

[0082] In steps S222 to S224, the location information inquiry means 140 of the non-geostationary satellite device S1 inquires the ground base station BS1 about the location information of the user terminal UE3 via the relay station.

[0083] In step S226, the ground base station BS1 identifies the location information of the user terminal UE3 by referring to the user area management table as shown in FIG. 11. Then, in steps S228 to S230, the ground base station BS1 transmits the location information of the user terminal UE3 to the non-geostationary satellite device S1 via the relay station.

[0084] Then, in S232, the user communication management means 130 of the non-geostationary satellite device S1 encapsulates the communication content addressed to the user terminal UE3 in association with the information (address of area 6) for identifying the geographical area corresponding to the position of the user terminal UE3 based on the location information of the user terminal UE3, and transmits it to the non-geostationary satellite device S6 via the relay station. FIG. 15 shows an example of the header information of the encapsulated communication content.

[0085] In step S234, the user communication management means 130 of the non-geostationary satellite device S6 releases the encapsulation and transmits the communication content addressed to the user terminal UE3 to the user terminal UE3.

[0086] Subsequently, with reference to FIG. 8, the operation when the connection destination of the user terminal UE1 is changed will be described.

[0087] In step S300, the non-geostationary satellite device S2 transmits a reference signal (reference burst) within the connectable range. The user terminal UE1 that has received the reference signal from the non-geostationary satellite device S2 transmits a connection request to the non-geostationary satellite device S2 in step S302. As a result, the connection destination of the user terminal UE1 changes from the non-geostationary satellite device S1 to the non-geostationary satellite device S2.

[0088] In step S304, the user terminal connection management means 121 of the non-geostationary satellite device S2 updates the location information in the user terminal management table T1 and transmits the updated location information to the adjacent non-geostationary satellite devices S1 and S3. Note that the non-geostationary satellite device S1 is the first adjacent non-geostationary satellite device described above, and the non-geostationary satellite device S3 is the second adjacent non-geostationary satellite device described above. FIG. 16 shows an example of the updated location information.

[0089] In step S306, the user terminal UE3 transmits the communication content addressed to the user terminal UE1 to the non-geostationary satellite device S6.

[0090] In step S308, the user communication management means 130 of the non-geostationary satellite device S6 encapsulates the communication content addressed to the user terminal UE1 in association with the information (address of area 1) for identifying the geographical area corresponding to the location of the user terminal UE1 and transmits it. As a result, it is assumed that the communication content reaches the non-geostationary satellite device S3. In this case, since the location information stored in the user terminal management table T1 of the non-geostationary satellite device S3 indicates that the user terminal UE1 is connected to the non-geostationary satellite device S2, in step S310, the user communication management means 130 of the non-geostationary satellite device S3 transmits the communication content addressed to the user terminal UE1 to the non-geostationary satellite device S2. Then, in step S312, the user communication management means 130 of the non-geostationary satellite device S2 transmits the communication content addressed to the user terminal UE1 to the user terminal UE1.

[0091] Also, in step S314, the user communication management means 130 of the non-geostationary satellite device S6 encapsulates the communication content addressed to the user terminal UE1 in association with the information (address of area 1) for identifying the geographical area corresponding to the location of the user terminal UE1 and transmits it. As a result, it is assumed that the communication content reaches the non-geostationary satellite device S1. In this case, since the location information stored in the user terminal management table T1 of the non-geostationary satellite device S1 indicates that the user terminal UE1 is connected to the non-geostationary satellite device S2, in step S318, the user communication management means 130 of the non-geostationary satellite device S1 transmits the communication content addressed to the user terminal UE1 to the non-geostationary satellite device S2. Then, in step S320, the user communication management means 130 of the non-geostationary satellite device S2 transmits the communication content addressed to the user terminal UE1 to the user terminal UE1.

[0092] FIG. 17 is a flowchart showing an example of the operation of the reception process in the non-geostationary satellite device 10.

[0093] In step S400, the non-geostationary satellite device 10 receives communication content from another non-geostationary satellite device 10. The header information of the communication content indicates, for example, the geographical area of the destination as shown in FIG. 13.

[0094] In step S402, the user communication management means 130 of the non-geostationary satellite device 10 determines whether the address indicating the destination geographical area included in the header information matches the address indicating the geographical area corresponding to the connectable range of the non-geostationary satellite device 10 identified by the area address management means 150.

[0095] If they do not match in step S402, in step S404, the user communication management means 130 transfers the communication content to another non-geostationary satellite device 10.

[0096] If they match in step S402, in step S406, the user communication management means 130 refers to the user terminal management table T1 to determine whether the user terminal UE indicated by the header information is the user terminal UE connected to the non-geostationary satellite device 10.

[0097] If it is not the user terminal UE connected to the non-geostationary satellite device 10 in step S406, in step S408, the user communication management means 130 refers to the location information management table T2 and transfers the communication content to the non-geostationary satellite device 10 to which the user terminal UE is connected.

[0098] If it is the user terminal UE connected to the non-geostationary satellite device 10 in step S406, in step S410, the user communication management means 130 de-capsulates the communication content and transfers the communication content to the user terminal UE.

[0099] Note that in step S408, the user communication management means 130 may change the address indicating the destination geographical area in the header information to the address identifying the non-geostationary satellite device 10 to which the user terminal UE is connected, and transfer the communication content to the non-geostationary satellite device 10. Thereby, the processing in the non-geostationary satellite device 10 as the transfer destination can be reduced.

[0100] Note that in the above description, the location information of the user terminal UE is determined by the position of the user terminal UE, but it is not necessarily the case that such a determination must be made. For example, there are a non-geostationary satellite device S1 corresponding to area 1 and a non-geostationary satellite device S2 corresponding to area 2. If a user terminal UE1 located in area 1 is connected to the non-geostationary satellite device S2, area 2 may be associated as the location information of the user terminal UE1.

[0101] Also, the procedure for the user terminal UE to change the connection destination is not particularly limited. In the example shown in FIG. 8, when the user terminal UE1 changes the connection destination from the non-geostationary satellite device S1 to the non-geostationary satellite device S2, the user terminal UE1 that has received the reference burst of the non-geostationary satellite device S2 makes a connection request to the non-geostationary satellite device S2, but it is not limited to this. For example, the user terminal UE1 that has received the reference burst of the non-geostationary satellite device S2 may transmit satellite information receivable by the non-geostationary satellite device S1 and switch the connection destination based on a handover instruction from the non-geostationary satellite device S1. Also, after the user terminal UE1 that has received the reference burst of the non-geostationary satellite device S2 makes a connection request to the non-geostationary satellite device S2, if a handover request is made from the non-geostationary satellite device S2 to the non-geostationary satellite device S1, the user terminal UE1 may switch the connection destination based on a handover instruction from the non-geostationary satellite device S1.

[0102] According to the simulations by the inventors, by applying the present disclosure, for example, the number of communication times and communication bandwidth for the management of location information between the non-geostationary satellite device 10 and the terrestrial base station BS, the number of communication times and communication bandwidth for the sharing of location information between adjacent non-geostationary satellite devices 10, the reduction of cache misses and the resulting reduction of delay in communication using location information, and other effects can be obtained.

[0103] 〔Example of implementation by software〕 Some or all of the functions of the non-geostationary satellite device 10 and the satellite mobile communication device 100 (hereinafter also referred to as "each of the above devices") may be realized by hardware such as an integrated circuit (IC chip), or may be realized by software.

[0104] In the latter case, each of the above devices is realized by, for example, a computer that executes instructions of a program that is software for realizing each function. An example of such a computer (hereinafter referred to as computer C) is shown in FIG. 18. FIG. 18 is a block diagram showing the hardware configuration of computer C that functions as each of the above devices.

[0105] Computer C includes at least one processor C1 and at least one memory C2. A program P for operating computer C as each of the above devices is recorded in memory C2. In computer C, processor C1 reads and executes program P from memory C2, whereby each function of each of the above devices is realized.

[0106] As processor C1, for example, a CPU (Central Processing Unit), GPU (Graphic Processing Unit), DSP (Digital Signal Processor), MPU (Micro Processing Unit), FPU (Floating point number Processing Unit), PPU (Physics Processing Unit), TPU (Tensor Processing Unit), quantum processor, microcontroller, or a combination thereof can be used. As memory C2, for example, a flash memory, HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof can be used.

[0107] Note that the computer C may further include a RAM (Random Access Memory) for expanding the program P during execution and temporarily storing various data. The computer C may further include a communication interface for transmitting and receiving data to and from other devices. The computer C may further include an input / output interface for connecting input / output devices such as a keyboard, a mouse, a display, and a printer.

[0108] In addition, the program P can be recorded on a non-transitory tangible recording medium M readable by the computer C. As such a recording medium M, for example, a tape, a disk, a card, a semiconductor memory, or a programmable logic circuit can be used. The computer C can obtain the program P via such a recording medium M. Also, the program P can be transmitted via a transmission medium. As such a transmission medium, for example, a communication network or a broadcast wave can be used. The computer C can also obtain the program P via such a transmission medium.

[0109] 〔Supplementary Note 1〕 The present disclosure includes the technologies described in the following supplementary notes. However, the present invention is not limited to the technologies described in the following supplementary notes, and various modifications are possible within the scope indicated in the claims.

[0110] (Supplementary Note 1) A satellite mobile communication system including a plurality of geostationary satellite devices, each geostationary satellite device comprising communication means for communicating with a ground user terminal and other geostationary satellite devices, a user terminal connected to the geostationary satellite device, and generation means for generating location information indicating an association between the geostationary satellite device and a geographical area corresponding to the location of the user terminal among a plurality of pre-set geographical areas on the ground.

[0111] (Supplementary Note 2) The satellite mobile communication system according to Supplementary Note 1, wherein each non-geostationary satellite device further comprises specifying means for specifying one or more of the geographical areas corresponding to the connectable range of the non-geostationary satellite device.

[0112] (Supplementary Note 3) The satellite mobile communication system according to Supplementary Note 2, wherein each non-geostationary satellite device further comprises transfer means for receiving communication content associated with identification information for identifying a geographical area from another non-geostationary satellite device, comparing the geographical area indicated by the identification information with the geographical area specified by the specifying means, and if they do not match, transferring the communication content to a non-geostationary satellite device different from the other non-geostationary satellite device.

[0113] (Supplementary Note 4) The satellite mobile communication system according to Supplementary Note 1, wherein each non-geostationary satellite device further comprises sending means for associating communication content addressed to a specific user terminal with information for identifying the geographical area corresponding to the position of the specific user terminal and transmitting the communication content to another non-geostationary satellite device.

[0114] (Supplementary Note 5) The satellite mobile communication system according to Supplementary Note 4, further comprising collecting means for collecting the location information generated by the generating means of each non-geostationary satellite device, and each non-geostationary satellite device further comprising obtaining means for obtaining the geographical area corresponding to the position of the specific user terminal from the collecting means.

[0115] (Supplementary Note 6) The satellite mobile communication system according to Supplementary Note 1, wherein each non-geostationary satellite device further comprises information sharing means for transmitting the location information to another non-geostationary satellite device.

[0116] (Supplementary Note 7) The information sharing means transmits the location information to at least one of a first neighboring non-geostationary satellite device and a second neighboring non-geostationary satellite device among the plurality of non-geostationary satellite devices. The first neighboring non-geostationary satellite device is a non-geostationary satellite device that includes the geographical area indicated by the location information within its connectable range. The second neighboring non-geostationary satellite device is a non-geostationary satellite device that includes the geographical area indicated by the location information within its next connectable range. The satellite mobile communication system according to Supplementary Note 6.

[0117] (Supplementary Note 8) A satellite mobile communication device provided in a non-geostationary satellite device that constitutes a satellite mobile communication system including a plurality of non-geostationary satellite devices, the satellite mobile communication device comprising: communication means for communicating with a ground user terminal and other non-geostationary satellite devices; a user terminal connected to the satellite mobile communication device; and generation means for generating location information indicating an association between the user terminal and a geographical area corresponding to the position of the user terminal among a plurality of geographical areas preset on the ground.

[0118] (Supplementary Note 9) A satellite mobile communication method using a satellite mobile communication system including a plurality of non-geostationary satellite devices, wherein at least one processor provided in each non-geostationary satellite device executes communication processing for communicating with a ground user terminal and other non-geostationary satellite devices, and generation processing for generating location information indicating an association between the user terminal connected to the non-geostationary satellite device and a geographical area corresponding to the position of the user terminal among a plurality of geographical areas preset on the ground.

[0119] (Supplementary Note 10) A satellite mobile communication program for operating a computer as a satellite mobile communication device included in a non-geostationary satellite device that constitutes a satellite mobile communication system including a plurality of non-geostationary satellite devices, the program causing the computer to function as communication means for communicating with a ground user terminal and other non-geostationary satellite devices, a user terminal connected to the satellite mobile communication device, and generation means for generating location information indicating an association between the user terminal and a geographical area corresponding to the location of the user terminal among a plurality of preset geographical areas on the ground.

[0120] [Supplementary Note 2] The present disclosure includes the technologies described in the following supplementary notes. However, the present invention is not limited to the technologies described in the following supplementary notes, and various modifications are possible within the scope indicated by the claims.

[0121] (Supplementary Note 1) A satellite mobile communication system including a plurality of non-geostationary satellite devices, each non-geostationary satellite device including at least one processor, the at least one processor executing communication processing for communicating with a ground user terminal and other non-geostationary satellite devices, and generation processing for generating location information indicating an association between a user terminal connected to the non-geostationary satellite device and a geographical area corresponding to the location of the user terminal among a plurality of preset geographical areas on the ground.

[0122] Note that the non-geostationary satellite device may further include a memory. Also, a program for causing the at least one processor to execute each of the above processes may be stored in the memory.

[0123] (Supplementary Note 2) A satellite mobile communication device included in a non-geostationary satellite device that constitutes a satellite mobile communication system including a plurality of non-geostationary satellite devices, comprising at least one processor, wherein the at least one processor performs communication processing for communicating with a terrestrial user terminal and other non-geostationary satellite devices, and a user terminal connected to the satellite mobile communication device, and generation processing for generating location information indicating an association between the user terminal and a geographical area corresponding to the location of the user terminal among a plurality of preset geographical areas on the ground.

[0124] Note that the non-geostationary satellite device may further include a memory. Further, a program for causing the at least one processor to execute each process may be stored in the memory.

Explanation of Signs

[0125] 1 Satellite mobile communication system 10, S1~Sn Non-geostationary satellite devices 100 Satellite mobile communication device 110 Communication means 120 Management means 121 User terminal connection management means 130 User communication management means 140 Location information inquiry means 150 Area address management means T1 User terminal management table T2 Location information management table T3 Area address management table

Claims

1. Comprising a plurality of non-geostationary satellite devices, Each non-geostationary satellite device, Communication means for communicating with a ground user terminal and other non-geostationary satellite devices, A user terminal connected to the non-geostationary satellite device, and generation means for generating location information indicating an association between the geographical area corresponding to the location of the user terminal and a plurality of preset geographical areas on the ground, a satellite mobile communication system.

2. Each non-geostationary satellite device, Further comprising specifying means for specifying one or more of the geographical areas corresponding to the connectable range of the non-geostationary satellite device, the satellite mobile communication system according to claim 1.

3. Each non-geostationary satellite device, Receives communication content associated with identification information for identifying a geographical area from another non-geostationary satellite device, and if the geographical area indicated by the identification information does not match the geographical area specified by the specifying means, further comprising transfer means for transferring the communication content to a non-geostationary satellite device different from the other non-geostationary satellite device, the satellite mobile communication system according to claim 2.

4. Each non-geostationary satellite device, Further comprising sending means for associating communication content addressed to a specific user terminal with information for identifying the geographical area corresponding to the location of the specific user terminal and sending it to other non-geostationary satellite devices, the satellite mobile communication system according to claim 1.

5. Further comprising collecting means for collecting the location information generated by the generating means of each non-geostationary satellite device, Each non-geostationary satellite device, Further comprising obtaining means for obtaining from the collecting means the geographical area corresponding to the location of the specific user terminal, the satellite mobile communication system according to claim 4.

6. Each non-geostationary satellite device, Further comprising information sharing means for transmitting the location information to other non-geostationary satellite devices, the satellite mobile communication system according to claim 1.

7. The information sharing means transmits the location information to at least one of a first neighboring non-geostationary satellite device and a second neighboring non-geostationary satellite device among the plurality of non-geostationary satellite devices, The first neighboring non-geostationary satellite device is a non-geostationary satellite device whose connectable range includes the geographical area indicated by the location information, The second neighboring non-geostationary satellite device is a non-geostationary satellite device whose connectable range includes the geographical area indicated by the location information next, the satellite mobile communication system according to claim 6.

8. A satellite mobile communication device included in a non-geostationary satellite device that constitutes a satellite mobile communication system including a plurality of non-geostationary satellite devices, communication means for communicating with a ground user terminal and other non-geostationary satellite devices, and generation means for generating location information indicating an association between a user terminal connected to the satellite mobile communication device and a geographical area corresponding to the position of the user terminal among a plurality of geographical areas preset on the ground. The satellite mobile communication device is provided with the above.

9. A satellite mobile communication method by a satellite mobile communication system including a plurality of non-geostationary satellite devices, wherein at least one processor included in each non-geostationary satellite device, performs communication processing for communicating with a ground user terminal and other non-geostationary satellite devices, and generation processing for generating location information indicating an association between a user terminal connected to the non-geostationary satellite device and a geographical area corresponding to the position of the user terminal among a plurality of geographical areas preset on the ground. The satellite mobile communication method is as described above.

10. A satellite mobile communication program for operating a computer as a satellite mobile communication device included in a non-geostationary satellite device that constitutes a satellite mobile communication system including a plurality of non-geostationary satellite devices, wherein the computer is caused to function as communication means for communicating with a ground user terminal and other non-geostationary satellite devices, generation means for generating location information indicating an association between a user terminal connected to the satellite mobile communication device and a geographical area corresponding to the position of the user terminal among a plurality of geographical areas preset on the ground. The satellite mobile communication program is as described above.

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