Communication device, communication system, communication method, and program

Abstract

To provide a communication device, a communication system, a communication method, and a program that improve the accuracy of predicting the availability of a wireless station in a non-terrestrial network (NTN).SOLUTION: A communication device 30 includes an NTN communication unit 39 connectable to an NTN, a sensor unit 38, and a control unit (processor 31). The control unit acquires presence information on the range of obstructions in space including the sending direction or the arriving direction of radio waves during communication by the NTN communication unit using the sensor unit, and executes processing based on the possible range in space where radio waves can be transmitted and received between the NTN communication unit and a non-terrestrial network, estimated from the acquired presence information.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] Conventionally, a technology has been considered for switching a wireless link for a communication terminal between a terrestrial base station and a satellite base station. In this technology, when the terrestrial base station in a disaster area stops and only the satellite base station can be used, the satellite base station establishes a wireless link preferentially with the communication terminal in the disaster area (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-134676 A [Patent Document 2] Special Publication No. 2022-545100 [Patent Document 3] JP 2006-133215 A [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP(registered trademark) TR 38.821 V16.2.0 (2023-03)(Release 16) Summary of the Invention [Problem to be solved by the invention]

[0005] However, radio stations of non-terrestrial networks (NTN: Non-Terrestrial Networks), including satellite base stations and HAPS (High Altitude Platform Stations), are often obstructed by obstacles. An aspect of the disclosed embodiments is to improve the accuracy of predicting the availability of wireless stations in an NTN. [Means for solving the problem]

[0006] The disclosed embodiment is exemplified by a communication device. The communication device includes an NTN communication unit connectable to a non-terrestrial network, a sensor unit, and a control unit. The control unit acquires presence information on the range of presence of an obstruction in space including the sending direction or the arriving direction of a radio wave during communication by the NTN communication unit using the sensor unit, and executes processing based on the possible range in space where radio waves can be transmitted and received between the NTN communication unit and the non-terrestrial network, which is estimated based on the acquired presence information. Effect of the Invention

[0007] The communication device can improve the accuracy of predicting the availability of radio stations in an NTN. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of an environment in which a vehicle equipped with a communication device according to a first embodiment travels. [Diagram 2] FIG. 2 is a diagram illustrating a vehicle in which a communication device is mounted and a group of devices related to the communication device. [Diagram 3] FIG. 3 is a diagram illustrating an example of a configuration included in a network. [Figure 4] FIG. 4 is a diagram illustrating a configuration of a communication device. [Diagram 5] FIG. 5 is a diagram illustrating an example of the configuration of an information processing device. [Figure 6] FIG. 6 is a diagram illustrating a travel route on which the LOS prediction and determination process is performed by the communication device. [Figure 7] FIG. 7 is a flowchart illustrating a communication method performed by the communication device mounted on the vehicle of the first embodiment. [Figure 8] FIG. 8 is a flowchart illustrating the details of the LOS prediction process. [Figure 9] FIG. 9 is a flowchart illustrating the process of the communication device of the second embodiment. [Figure 10] FIG. 10 is a flowchart illustrating the process of the communication device of the third embodiment. [Figure 11] FIG. 11 is a flowchart illustrating details of the LOS and communication quality prediction process according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the communication device 30, the communication system 100, the communication method, and the program of the present embodiment will be described with reference to the drawings. The communication device 30 includes an NTN communication unit 39 connectable to a non-terrestrial network, a sensor 38, and a control unit (see Figs. 1, 2, 4, etc.). The control unit acquires presence information on the range of the presence of an obstruction in a space including the sending direction or the arriving direction of a radio wave during communication by the NTN communication unit 39, using the sensor 38. Then, the control unit executes processing based on the possible range in the space where radio waves can be transmitted and received between the NTN communication unit 39 and the non-terrestrial network, which is estimated based on the acquired presence information. Note that, in the space including the sending direction or the arriving direction of the radio wave, there exists an NTN radio station 6 to which the non-terrestrial network is connected.

[0010] The communication device 30 can move, for example, by being mounted on a moving object or carried by a user. Therefore, it is assumed that the presence information changes as the communication device 30 moves. Therefore, the control unit repeatedly predicts the movement route of the communication device 30 in a time section from the current time to a future time when a predetermined time has passed. Then, the control unit obtains presence information regarding the presence range of an obstacle on the movement route of the communication device 30 in the time section up to the future time. The communication device 30 may estimate this presence information by its own information processing. In addition, the communication device 30 may receive the presence information from the information processing device 4, database 7, etc. on the network N1 connected via the NTN communication unit 39 or the TN communication unit (communication IF 33 in FIG. 4) connectable to a ground network (see FIG. 1 and FIG. 4).

[0011] <First embodiment> (System configuration) Hereinafter, with reference to FIG. 1 to FIG. 8, a vehicle 3 as a moving body of the first embodiment, a communication device 30 mounted on the vehicle 3, and a communication system 100 including the communication device 30 are illustrated. FIG. 1 is a diagram illustrating an environment in which vehicles 3A and 3B mounted with the communication device 30 of the first embodiment travel. The vehicles 3A, 3B, etc. are collectively referred to as vehicles 3. The number of vehicles 3 included in the communication system 100 may be one or three or more. The moving body is not limited to a four-wheeled vehicle, and may be a two-wheeled vehicle, a bicycle, etc. The moving body may be a ship, or an air vehicle capable of moving in space, such as a drone, or an aircraft. As shown in FIG. 1, the vehicle 3 as a moving body is equipped with the communication device 30 of this embodiment.

[0012] In Fig. 1, the line of sight toward the page is also called the depth direction. Meanwhile, in Fig. 1, the opposite direction to the line of sight toward the page is also called the front direction. In Fig. 3, there are mountains in the distance in the depth direction. Vehicle 3A is traveling in the left lane RL1 of the road from the front side to the depth direction of the drawing. Meanwhile, vehicle 3B is traveling in the right lane RL2 of the road from the depth side to the front side of the drawing.

[0013] Also, near the road on which vehicle 3A is traveling, which is closer to the front of the drawing, there are obstacles on both sides of the road. On the other hand, near the road on which vehicle 3B is traveling, which is closer to the back of the drawing, there are no obstacles and there is a wider space with a wider view than near the road on which vehicle 3A is traveling. , NTN radio station 6 is shown in the sky above the distant mountains.

[0014] The NTN radio station 6 is a communication satellite, a HAPS, or the like, and is equipped with an NTN communication device 60. Communication satellites include GSO (Geosynchronous Orbit) satellites and NGSO (Non-Geosynchronous Orbit) satellites.

[0015] The NTN radio station 6 is connected to a terrestrial communication device 30 or UE2 (see FIG. 2) via a line called a service link. If the NTN radio station 6 is a GSO satellite, the service link can be provided by a radio wave beam that is fixed on the Earth and always covers the same area. On the other hand, if the NTN radio station 6 is not a GSO satellite, the service link can be provided by a quasi-Earth-fixed type or an Earth-moving type radio wave beam. It is possible to provide.

[0016] Here, in the case of an Earth-moving type radio wave beam, a cell in the NTN (hereinafter, an NTN cell) moves on the ground as an NTN radio station 6 (such as an NGSO satellite) moves on the orbital plane. Here, an NTN cell refers to a communication range that one NTN radio station 6 covers at a certain point in time. Also, in the case of a quasi-Earth fixed type, different beams for each period of time are stationary on a given NTN cell on the ground for a certain period of time. The cross section of each beam through the earth's surface is called a footprint. The quasi-Earth fixed type radio wave beam can be formed by an NTN radio station 6 that generates a steerable beam to fix the footprint on the ground at a certain time.

[0017] The NTN communication device 60 mounted on the NTN radio station 6 connects the ground communication device 30, the UE 2, etc. to a mobile communication system such as a 5G core network (5GC). Note that in this embodiment and the following embodiments, an example of application of the communication system 100 to a fifth generation mobile communication system is exemplified. However, the communication system 100 of this embodiment may be applied to a fourth generation or fifth generation or later mobile communication system.

[0018] The NTN communication device 60 connects the terrestrial communication device 30, UE2, etc. to the mobile communication system by transparent relay or regenerative relay. In "transparent relay," the waveform of the relayed radio signal is not changed. On the other hand, in regenerative relay, demodulation, decoding, switching, routing, encoding, modulation, etc. of the radio signal are performed. Therefore, the NTN communication device 60 and the NTN radio station 6 that perform regenerative relay are called gNBs (next generation nodes). It can be said that all or part of the functions of ground base stations such as B) are installed on communications satellites or HAPS, etc.

[0019] The NTN communication device 60 is connected to a terrestrial NTN gateway via a communication line called a feeder link. In transparent relay, the NTN gateway connects the NTN communication device 60 to a terrestrial base station (gNB, etc.) of the mobile communication system. On the other hand, in regenerative relay, the NTN gateway may connect the NTN communication device 60 directly to a core network (5GC, etc.) of the mobile communication system without going through a terrestrial base station (gNB, etc.).

[0020] 2 is a diagram illustrating a vehicle 3 equipped with a communication device 30 according to the present embodiment and a group of devices related to the communication device 30. In FIG. 2, as the group of devices related to the communication device 30, a UE2 (User Equipment), an information processing device 4, a database 7, and an NTN radio station 6 connected to a network N1 including a mobile communication system are illustrated. The network N1 is, for example, a mobile communication system that supports LTE (Long Term Evolution), a fifth generation mobile communication system (5G), and a sixth generation mobile communication system (6G). This includes mobile communication systems such as the 6th generation mobile communication system (6G), wireless LANs (Local Area Networks), etc. In Fig. 2, the solid lines exemplify wired communication lines, and the dotted lines exemplify wireless communication lines, for example.

[0021] The UE2 is called a mobile terminal, a smartphone, etc. The UE2 accesses the network N1 via a base station included in the network N1. The UE2 may also access the network N1 via a communication line called a service link and an NTN radio station 6.

[0022] The communication device 30 has a similar configuration to the UE 2 and executes similar processing. However, the communication device 30 is connected to a sensor 38 (see FIG. 4) on the vehicle 3. The communication device 30 detects the presence or absence of an obstruction in the surrounding space on the moving path of the vehicle 3 while it is traveling, using the sensor 38. Furthermore, the communication device 30 acquires orbital information (Ephemeris information) of the NTN radio station 6 from the network N1 via the NTN radio station 6, or directly from the network N1 without going through the NTN radio station 6. The orbital information includes, for example, time (day, hour, minute, second, Epoch), position (X, Y, Z) and velocity (dX / dt, dY / dt, dZ / dt) in Earth-centered, Earth-fixed (ECEF) Cartesian coordinates. However, the orbital information may be coordinates and velocity in polar coordinates (phi, lambda, a, b) of a spheroid. Here, a is, for example, the equatorial semicircle of the spheroid. The radius of the orbit is the polar radius, b is the polar radius of the orbit, phi is the latitude, and lambda is the longitude. The information may be in True Equator Mean Equinox (TEME) coordinates.

[0023] The communication device 30 acquires the trajectory information from the NTN radio station 6 or a base station of a radio access network connected to the network N1. For example, when the communication device 30 is connected to an LTE or 5G core network (5GC), the trajectory information can be acquired in a system information block (SIB). The procedure by which the communication device 30 (and the UE2) acquires the SIB from the 5GC is specified in 3GPP (registered trademark) 38.331. Note that the communication device 30 may acquire, from the network N1, the trajectory information of the currently connected NTN radio station 6 and the trajectory information of the NTN radio station 6 covering a candidate NTN cell to which the communication device 30 is connected in a predetermined time ΔT.

[0024] In this embodiment, the information processing device 4 is a server that manages the orbital information of all NTN radio stations 6 or a data storage device that stores the information, similar to A (Assisted)-GPS (Global Positioning System). The information processing device 4 operates as a database and provides trajectory information of the NTN radio stations 6. Therefore, by making an inquiry to the information processing device 4, the communication device 30 can obtain trajectory information of the NTN radio stations 6 that cover the NTN cells that are candidates for connection to the communication device 30 in a predetermined time ΔT. However, the server that manages the trajectory information of all NTN radio stations 6 or the database that holds the information is not limited to the information processing device 4.

[0025] For example, a communication carrier that manages and provides a mobile communication system (see FIG. 3) included in the network N1 may connect a server that manages the orbit information of all NTN radio stations 6 or a database that holds the information to the DN5. Also, the server that manages the orbit information of all NTN radio stations 6 or the database that holds the information may be provided as AF12 in FIG. 3 so as to be accessible from the communication device 30. Also, as one of the functions of NEF11e in FIG. 3, the orbit information of all NTN radio stations 6 may be provided. Furthermore, in 5G, 6G, and other communication standards, the provision of such orbit information may be stipulated as one of the functions of NF11 such as NEF11e. In this way, the communication device 30 queries the information processing device 4, other servers, or databases for "NTN radio stations that exist in a time period before or after a certain time in the vicinity of a specified point (current point, future point)".

[0026] Then, the communication device 30 determines the feasible range (LOS (Line Of Sight)) in which radio waves can be transmitted and received between the communication device 30 and the NTN radio station 6 on the travel route while traveling, based on the obstacles on the route while traveling and the trajectory information of the NTN radio station 6.

[0027] The communication device 30 is equipped with a sensor 38. The sensor 38 may be, for example, a radar, a camera, or The sensor 38 is a receiver that detects reflected waves from an obstacle of an electromagnetic wave emitted from the communication IF 33 (see FIG. 4). For example, the sensor 38 has a laser irradiation device and a photodetector that can scan a two-dimensional plane in front of the vehicle 3. The sensor 38 detects an obstacle in front of the vehicle 3 by scanning a two-dimensional plane in front of the vehicle 3 with a laser and receiving reflected light. The sensor 38 may also be a three-dimensional millimeter wave radar that combines a transmitter that irradiates multiple pencil beams in front of the vehicle 3 and a receiver that receives reflected waves from the front of the vehicle 3 with a gain pattern of multiple pencil beams. The transmitter may also be the communication IF 33 (see FIG. 4) that connects to a base station of a wireless access network. Therefore, the sensor 38 detects three-dimensional presence information regarding the presence range of obstacles in front of and around the vehicle 3 on the moving route of the vehicle 3.

[0028] Furthermore, the sensor 38 may have a processor and a camera and capture an image of the area ahead of the vehicle 3. The processor may recognize an obstacle ahead of the vehicle 3 from the image captured by the camera, and notify the communication device 30 of information such as the height and depth of the obstacle as seen from the vehicle 3.

[0029] The communication device 30 may also acquire a 3D (dimension) MAP of the surroundings of the vehicle 3 from a database 7 connected to the network N1. The LOS can be identified by adding presence information regarding the range of the obstruction detected by the sensor 38 to the 3D MAP information acquired from the .

[0030] Furthermore, the communication device 30 may predict the LOS from the present to a predetermined time ΔT in the future. For example, the communication device 30 may update the information of the 3D MAP around the vehicle 3 from time to time based on the current position information, driving speed, acceleration, driving direction, destination, and information on obstacles detected by the sensor 38, and estimate the LOS. Furthermore, the communication device 30 may transfer the current position information, driving speed, acceleration, driving direction, destination, and information on obstacles detected by the sensor 38 of the vehicle 3 to the information processing device 4 and request it to calculate the LOS from the present time to a predetermined time ΔT in the future.

[0031] The information processing device 4 provides a LOS calculation service to the communication device 30, UE2, etc. For example, the information processing device 4 receives a request from the communication device 30, etc., to calculate the LOS from the current time point to a predetermined time ΔT in the future, together with the current position information, the running speed, the acceleration, the running direction, the destination, and information on the obstruction detected by the sensor 38, etc. At this time, the information processing device 4 may acquire from its own storage device 32 the trajectory information of the NTN radio station 6 to which the communication device 30 is currently connected and the trajectory information of the NTN radio station 6 covering the cell that is a candidate to which the communication device 30 and UE2 are connected in the predetermined time ΔT. However, as described above, the information processing device 4 may acquire the above trajectory information from a server, database, etc. connected to the DN5 of 5GC. The information processing device 4 may also acquire the above trajectory information from a server, database, etc. provided as the AF12 of 5GC.

[0032] As described above, in this embodiment, the information processing device 4 executes processing as a server that manages the trajectory information of all NTN radio stations 6 or a database that holds information. Therefore, the information processing device 4 may be a server that can receive a request from the communication device 30 and respond with "NTN radio stations that exist in the time period before and after the specified time in the vicinity of the specified point (current point, future point)."

[0033] Furthermore, the information processing device 4 may acquire a 3D MAP of the movement route from the current position of the communication device 30 to the destination in the database 7, for example. However, the information processing device 4 may store and read out the 3D MAP of the movement route of the communication device 30 in the storage device 42 (see FIG. 4). The information processing device 4 may be, for example, a computer connected to the DN5 (see FIG. 3) of the 5GC. Furthermore, the information processing device 4 may be, for example, the AF12 (see FIG. 3) of the 5GC.

[0034] The database 7 updates the information of the 3D MAP on the ground and provides the latest 3D MAP information to the communication device 30, UE2, and the like. The 3D MAP is map information that is three-dimensionalized by adding information in the vertical direction (height direction and depth direction) to two-dimensional map information. The database 7 collects, for example, three-dimensional information of the surroundings of the communication device 30, UE2, and the like from the communication device 30, UE2, and other devices connected to the network N1, together with two-dimensional position information of the respective locations. The three-dimensional information may be information based on images captured by a camera mounted on the vehicle 3 or other moving body and a camera mounted on the UE2, and the like. The database 7 updates the 3D MAP information every moment based on the collected images or three-dimensional information, and the like. The database 7 provides the current 3D MAP information to the communication device 30 and UE2 in response to requests from the communication device 30, UE2, and the like.

[0035] The database 7 stores 3D MAP information that does not change much over time in the storage device 42 (see FIG. 4). The database 7 obtains the latest three-dimensional information about the surroundings of the UE 2 from the UE 2 connected to the network N1, and updates the 3D MAP. For example, the database 7 obtains three-dimensional information such as the position, height, and width of a newly constructed building from the UE 2 connected to the network N1. Such information can also be called real-time information. The UE 2 that provides the real-time information can be called a device that executes sensing processing.

[0036] The database 7 can also be a computer that accumulates information collected by the device in the past. The database 7 may be, for example, a computer connected to the DN5 of the 5GC (see FIG. 3). The database 7 may also be, for example, the AF12 of the 5GC (see FIG. 3).

[0037] FIG. 3 is a diagram illustrating a configuration of a mobile communication system included in the network N1. FIG. 3 also illustrates a fifth generation mobile communication system (also called a 5G network or 5GNW (Network)). 1. However, as already mentioned, the network N1 is not limited to a 5G network, but may be an LTE network or a network including a mobile communication system of 6G or later. In FIG. 1, UE2 is a terminal of a user (subscriber). As shown in FIG. 4, the communication device 30 has the same configuration as the UE2. The RAN (Radio Access Network) 3 is an access network to the 5G core network (5GC). The RAN 3 is composed of a base station (gNB).

[0038] The 5G network has a 5G core network (5GC) and an access network ((R)AN), and the above-mentioned UE2, DN (Data Network) 5, and AF (Application Function) 12 are connected to the 5G network. The 5GC also has NFs 11a to 11e and 11g to 11k (hereinafter referred to as NFs 11a to 11k), which are indicated in bold. Each of the NFs 11a to 11k is a function realized by one or more computers executing a program. However, a single computer may realize two or more of the NFs 11a to 11k. In this embodiment, the components of the 5GC are collectively referred to as NFs 11 (Network Functions 11). The components of the 5GC are individually referred to as NEFs 11e, etc. In FIG. 1, each component is given an individual symbol in parentheses along with a generic symbol.

[0039] As mentioned above, 5GC is composed of a set of components with specific functions called NF11. Figure 3 shows the following NF11 that composes 5GC. In Figure 3, NF11 is shown as a thick rectangle. UPF(User Plane Function)11a AMF (Access and Mobility Management Function)11b SMF (Session Management Function)11c PCF(Policy Control Function)11d NEF(Network Exposure Function)11e NRF(Network Repository Function)11g NSSF(Network Slice Selection Function)11h AUSF(Authentication Server Function)11i UDM(Unified Data Management)11j NWDAF(Network Data Analytics Function)11k In this embodiment, user plane packets transmitted and received by UE2 are called user packets. UPF11a routes and forwards user packets, inspects packets, and processes QoS. AMF11b is a device for accommodating UE2 in the area in 5GC. AMF11b accommodates RAN3, and performs subscriber authentication control, location (mobility) management of UE2, etc.

[0040] The SMF 11c manages a PDU (Protocol Data Unit) session and controls the UPF 11a to implement QoS (Quality of Service) control and policy control. The PDU session is a virtual communication path for exchanging data between the UE 2 and the DN 5. The DN 5 is a data network (such as the Internet) outside the 5GC.

[0041] The PCF 11d cooperates with the SMF 11c to perform QoS control, policy control, billing control, etc. QoS control involves controlling the quality of communication, such as by prioritizing packet forwarding, while policy control involves controlling communication, such as QoS based on network or subscriber information, whether or not to forward packets, and billing.

[0042] NEF11e plays a role of mediating communication between AF12 or a node outside 5GC and NF11 of 3GPP (registered trademark). For example, NEF11e securely publishes the functions and events of each NF11 to a third party, AF12, edge computer, etc. NEF11e also converts between internal information of 5GC and external information. NEF11e converts, for example, information handled by AF12 and information handled by each NF11 of 5GC. For example, NEF11e converts between a service identifier in AF12 and 5GC internal information.

[0043] AF12 is an element that interacts with 5GC to provide services to users, and is called, for example, an external application server. AF12, which is considered to be trusted by the 5G network operator, can directly access NF11 related to 5GC. AF12, which is not permitted to directly access NF11 related to 5GC, uses an interface exposed externally via NEF11e to access the network functions of 5GC.

[0044] The NRF 11g stores and manages information on the NFs 11 (for example, the AMF 11b, the SMF 11c, the UPF 11a, etc.) in the 5GC. In response to an inquiry about an NF 11 desired to be used, the NRF 11g can return multiple NF 11 candidates to the inquiry source.

[0045] The NSSF11h has a function of selecting a network slice to be used by a subscriber from among the network slices generated by network slicing. A network slice is a virtual network with specifications according to the application.

[0046] The AUSF 11i is a subscriber authentication server that performs subscriber authentication under the control of the AMF 11b. The UDM 11j holds or manages subscriber-related information. The subscriber-related information can be said to be an example of contract data. The contract data is, for example, information based on a contract between a user of the communication device 30 (and the UE 2) and a business operator (also called an operator, or MNO (Mobile Network Operator)) that manages the mobile communication system. The UDM 11j holds or manages the subscriber-related information. It provides information to each NF 11, or acquires, registers, deletes, or changes the status of UE 2.

[0047] The NWDAF11k has the function of collecting and analyzing data from each NF11, OAM (Operations, Administration, and Maintenance) terminal, etc. operates, manages and maintains the network (5GC). In other words, NWDAF11k is the NF11 that provides analysis information on the network.

[0048] The DN5 is a network outside the communication system, for example, the Internet. The DN5 is connected to the communication network provided by this communication system (5GC) via one of the UPFs 11a. The UPF 11a can have a multi-stage configuration. The final stage UPF 11a connected to the DN5 is called a PSA UPF (PDU Session Anchor User Plane Function). The UPF 11a provided between the RAN3 and the PSA UPF is called an I (Intermediary) UPF.

[0049] In the example of FIG. 3, the information processing device 4 and the database 7 are connected to the DN5. The information processing device 4 and the database 7 have already been described in FIG. 2. Furthermore, in FIG. 2, the LOS calculation AF12a and the 3D MAP AF12b are provided in a position parallel to the AF12. The LOS calculation AF12a calculates the LOS on the moving route of the user's device, that is, the communication device 30, the UE2, etc., as the AF12, and provides the communication device 30, the UE2, etc. with LOS information as the calculation result. That is, the LOS calculation AF12a provides the same processing as the information processing device 4. Furthermore, the 3D MAP AF12b updates the 3D MAP as the AF12, and provides it to the communication device 30, the UE2, the LOS calculation AF12a, or the information processing device 4. That is, the 3D MAP AF12b provides the same processing as the database 7.

[0050] <Configuration of information processing device and terminal> FIG. 4 is a diagram illustrating a configuration of the communication device 30. The communication device 30 is a device mounted on a moving body such as a vehicle 3 and accesses a mobile communication system, and has the same configuration as the UE 2. The communication device 30 includes a processor 31 as a processing unit or control unit (controller), a storage device 32, a communication interface 33 (communication IF 33), an NTN communication unit 39, an input device 34, and a display 35, which are mutually connected via a bus 36. The communication device 30 may also be connected to a sensor 38 via an interface (referred to as I / F 37). The sensor 38 is, for example, a radar, a camera, etc., as described in FIG. 2. Note that the communication device 30 may use a transmitter of the communication IF 33 as a substitute for a transmitter of the sensor 38.

[0051] The storage device 32 includes a main storage device and an auxiliary storage device. The main storage device is used as at least one of a storage area for programs and data, a program development area, a program work area, and a buffer area for communication data. The main storage device is configured with a RAM (Random Access Memory) or a combination of a RAM and a ROM (Read Only Memory). The auxiliary storage device is used as a storage area for data and programs. A non-volatile storage medium is applied to the auxiliary storage device. Examples of the non-volatile storage medium include a hard disk, a Solid State Drive (SSD), a flash memory, and an EEPROM (Electrically Erasable Programmable Read-Only Memory). The storage device 22 may also include a drive device for a disk recording medium.

[0052] The communication IF 33 is a circuit that performs communication processing. For example, the communication IF 33 is a transmitter and a receiver that access a base station (gNB) of a mobile communication system such as 5G. Also, for example, the communication IF 33 is a network interface card (NIC). Also, the communication IF 33 may be a wireless communication circuit that performs wireless communication (5G, wireless LAN (Wi-Fi (registered trademark)), BLE (Bluetooth (registered trademark) Low Energy), etc.). Also, the communication IF The NTN communication unit 39 is a transmitter and a receiver that communicates with the NTN radio station 6 in the sky via a service link.

[0053] The input device 34 includes a key, a button, a pointing device, a touch panel, etc., and is used to input information. The display 35 is, for example, a liquid crystal display, an OEL (Organic Electro-Luminescence) display, etc. The display 25 displays information and data.

[0054] FIG. 5 is a diagram illustrating the configuration of the information processing device 4. However, it can be said that FIG. 5 illustrates the configuration of the NFs 11a to 11k, the AFs 12, the LOS calculation AFs 12a, the 3D MAP AFs 12b, the database 7, and the like. The information processing device 4 can be configured using a dedicated or general-purpose computer such as a personal computer (PC), a workstation (WS), or a server machine. However, the information processing device 4 may be a collection (cloud) of one or more computers. The information processing device 4 includes a processor 41, a storage device 42, a communication interface 43 (communication IF 43), an input device 44, and a display 45, which are mutually connected via a bus 46. The processor 41, the storage device 42, the communication IF 43, the input device 44, and the display 45 can be the same as the processor 31, the storage device 32, the communication IF 33, the input device 34, and the display 35. Therefore, the description of these is omitted.

[0055] The processors 31 and 41 perform various processes by executing various programs stored in the storage device 32. The processors 31 and 41 are, for example, CPUs (Central Processing Units). A CPU is also called an MPU (Microprocessor Unit). The processors 31 and 41 may have a single processor configuration or a multiprocessor configuration. Also, a single physical CPU connected via a single socket may have a multicore configuration. The processors 31 and 41 may include arithmetic devices of various circuit configurations, such as a DSP (Digital Signal Processor) or a Graphics Processing Unit (GPU). Also, the processors 31 and 41 may have a configuration in cooperation with at least one of an integrated circuit (IC), other digital circuits, and analog circuits. The integrated circuit may be an LSI, an ASIC (Application Specific Integrated Circuit), or a programmable logic The PLD includes, for example, a field-programmable gate array (FPGA). The processors 31 and 41 include, for example, a microcontroller (MCU). This also includes what are called SoC (System-on-a-chip), system LSI, or chipset.

[0056] (Example of processing) Fig. 6 is a diagram illustrating a travel route on which the communication device 30 performs LOS prediction and availability determination processing. In Fig. 6, footprints FP1 to FP8 are illustrated as cross sections on the ground surface of beams from an NTN radio station 6 on the travel route on which the vehicle 3 travels during a predetermined time ΔT. The NTN radio station 6 may be, for example, a GSO satellite, an NGSO satellite, or a HAPS.

[0057] If NTN Radio Station 6 is an NGSO satellite or HAPS providing an Earth-moving type service link, footprints FP1 to FP8 are When the NTN radio station 6 moves in the orbital plane, it moves on the ground. If the NTN radio station 6 is an NGSO satellite or a HAPS and provides a Quasi-Earth-fixed type service link, In the case where the NTN radio station 6 is a GSO satellite, the footprints FP1 to FP8 are stationary at a certain time on the NTN cell at each location. On the other hand, if the NTN radio station 6 is a GSO satellite, the service link and the NTN cell are earth-fixed and always cover the same area.

[0058] The communication device 30 acquires, for example, by the SIB, trajectory information of the NTN radio station 6 on the moving route that moves a predetermined time ΔT from the current position of the vehicle 1 from time to time. As described in FIG. 2, the trajectory information includes, for example, time (day, hour, minute, second, Epoch), Earth-centered, Earth-fixed (ECEF) orthogonal, Includes coordinates (X, Y, Z) and velocities (dX / dt, dY / dt, dZ / dt), although orbit information may also include coordinates and velocities in ellipsoidal polar coordinates (phi, lambda, a, b). .

[0059] Moreover, the communication device 30 momentarily calculates the LOS on the travel route that moves a predetermined time ΔT from the current position of the vehicle 1, or acquires it from the information processing device 4. Therefore, the communication device 30 momentarily identifies footprints FP1 to FP8 that reflect the LOS on the travel route that moves a predetermined time ΔT from the current position of the vehicle 1.

[0060] In the moving route exemplified by LOS1 on the left side of Fig. 6, footprints FP1 to FP8 reflecting the LOS are all connected. That is, LOS1 is an example of no interruption. In the example of LOS1, the communication device 30 determines that it is possible to connect to the NTN wireless station 6 without interruption on the moving route that moves a predetermined time ΔT from the current position.

[0061] On the other hand, in the moving route exemplified by LOS2 on the right side of FIG. 6, there is an interruption point Z1 between footprints FP6 and FP7. Also, there is an interruption point Z2 between footprints FP7 and FP8. That is, LOS2 is an example where there is an interruption. In the example of LOS2, the communication device 30 determines that the connection with the NTN radio station 6 is interrupted at the interruption points Z1, Z2, etc. on the moving route moving a predetermined time ΔT from the current position. The communication device 30 continues communication with the network N1 by connecting to, for example, a terrestrial base station immediately before reaching the interruption points Z1, Z2.

[0062] Fig. 7 is a flowchart illustrating a communication method by the communication device 30 mounted on the vehicle 3. This process is started, for example, by turning on the power of the communication device 30 or turning on the power of an accessory of the vehicle 3. In this process, the communication device 30 repeatedly executes the process of Fig. 7 every predetermined time ΔT (S1). The repetition started by S1 is called LOOP1.

[0063] In LOOP1, the communication device 30 acquires the current time, the current location where the vehicle 3 is located, the moving speed of the vehicle 3, etc. (S2). Next, the communication device 30 acquires trajectory information (position and moving speed) of the NTN radio station 6, etc. available in a section where the vehicle 3 can move at the acquired moving speed for a predetermined time ΔT (S3). For example, the communication device 30 acquires the position and moving speed of the currently connected NTN radio station 6. In addition, when another NTN radio station provides an NTN cell around the NTN cell provided by the NTN radio station 6 and on the moving route, the communication device 30 acquires the position and moving speed of the other NTN radio station. On the moving route is a route along which the vehicle 3 moves at the moving speed acquired in S2 for a predetermined time ΔT. This moving route is a section in which the connection of the NTN radio station 6, etc. is predicted to be maintained, and is also called a predicted section. In addition, the NTN cell around the NTN cell provided by the NTN radio station 6 is exemplified by an NTN cell that is a handover destination for the NTN cell provided by the NTN radio station 6, for example.

[0064] The NTN wireless station 6 and the other NTN wireless stations described above provide NTN cells available on the moving route (prediction section), and are referred to as NTN wireless stations 6, etc. In addition to the current position and moving speed of the NTN radio station 6, etc., the planned position and planned moving speed of the NTN radio station 6, etc. predicted in the future within a predetermined time ΔT, which is the period in which LOOP1 is executed, may be acquired from the information processing device 4, other servers or databases on the network N1. In this way, the communication device 30 may acquire the planned predicted position of the NTN radio station 6, etc. in the predetermined time ΔT, which is the LOS prediction period, from the network N1 along with the current position of the NTN radio station 6, etc., and store it in the storage device 32. The above-mentioned trajectory information of the NTN radio station 6, etc. may be acquired via the NTN radio station 6, or may be acquired via a ground base station and a ground network. Then, the communication device 30 executes a repeated process for each NTN radio station 6, etc. for which trajectory information has been acquired (S4). This repetition is called LOOP2.

[0065] Then, the communication device 30 predicts LOS to the NTN wireless station 6 for each point and time on the movement route (prediction section) in the movement direction of the vehicle 3 (S5). Details of the processing of S5 will be described separately with reference to FIG. 8. Then, the communication device 30 judges whether or not LOOP2 has ended (S6). That is, the communication device 30 judges whether or not LOOP2 has been executed for all NTN wireless stations 6, etc. If LOOP2 has not ended, the communication device 30 returns the processing to S4 and continues LOOP2.

[0066] On the other hand, when LOOP2 ends, the communication device 30 judges whether or not the connection to the NTN wireless station 6, etc. continues and is maintained within the prediction interval (S7). If the connection to the NTN wireless station 6, etc. continues and is maintained within the prediction interval, the communication device 30 activates or maintains NTN communication (S8). On the other hand, if the connection to the NTN wireless station 6, etc. is not maintained within the prediction interval, the communication device 30 activates or maintains TN (Terrestrial Network) communication such as cellular communication or wireless LAN communication. The communication is enabled (S9). In this example, the communication device 30 switches from NTN communication to TN communication.

[0067] Then, the communication device 30 determines whether LOOP1 has ended (S10). LOOP1 ends when, for example, the power of the communication device 30 is turned off or the power of an accessory of the vehicle 3 is turned off. If LOOP1 has not ended, the communication device 30 returns the process to S1 and continues LOOP1. On the other hand, if the power or the like is turned off, the communication device 30 ends the process.

[0068] In the process of S9, the communication device 30 may use NTN communication in combination with TN communication. This is because the connection to the NTN radio station 6 or the like continues at least partially within the prediction interval. Here, using both means that the communication device 30 maintains the connection to the NTN radio station 6 via the NTN communication unit 39, and the communication IF 33, which is the TN communication unit, maintains the connection to the ground base station. By using both in combination in this way, the communication device 30 can switch to TN communication in a short time even if the connection to the NTN radio station 6 or the like is interrupted.

[0069] FIG. 8 is a flowchart illustrating the details of the LOS prediction process (S5 in FIG. 7). The communication device 30 executes repetition (k=0 to N) for each time interval Δt within a predetermined time ΔT, which is an LOS prediction period (S51). The repetition for each time interval Δt is called LOOP3. The number of repetitions k=0 corresponds to the current time, and ΔT=N*Δt. The time interval Δt is, for example, a time period that can follow the change in LOS associated with the movement of the vehicle 3. Note that, instead of executing repetition for each time interval Δt, the communication device 30 may repeat the process of LOOP3 for each NTN cell that overlaps with the movement path (prediction section) that moves during the predetermined time ΔT.

[0070] In LOOP3, for example, the communication device 30 predicts the position (CX=CVx*Δt, CY=CVy*Δt) of the vehicle 3 at time k*ΔT based on the speed of the vehicle 3 (S52). where (CVx, CVy) is the speed of the vehicle 3. Here, the origin (0,0) of the position of the vehicle 3 is set to the current location. However, the communication device 30 may obtain the road conditions and traffic congestion conditions of the current travel route from a car navigation system or the like, and correct the speed of the vehicle 3.

[0071] Furthermore, the communication device 30 predicts the positions (NX=NVx*Δt, NY=NVy*Δt, NZ=NVz*Δt) of the NTN radio stations 6, etc. at time k*ΔT based on the current orbit information (time, position, speed) of the NTN radio stations 6, etc. (S53), where (NVx, NVy, NVz) are the speeds of the NTN radio stations 6, etc.

[0072] However, instead of predicting the position of the NTN radio station 6 etc. in S53, the communication device 30 may read out the expected positions of the NTN radio station 6 etc. within a predetermined time ΔT, which have been acquired in advance, from the storage device 32 in the process of S3 in FIG. 7. In addition, the orbit information (time, position, speed) of the NTN radio station 6 etc. may be expressed in polar coordinates (phi, lambda, a, b) of an ellipsoid. The receiving device 30 determines the range of the NTN cell (or footprint) provided by the beam of the NTN wireless station 6, etc. at time k*ΔT.

[0073] The communication device 30 also acquires a 3D MAP reflecting the obstruction at the position (CX, CY) of the vehicle 3 (S54). For example, the communication device 30 acquires a 3D MAP at the position of the vehicle 3 at time k*ΔT from the database 7 via the network N1. However, when the communication device 30 acquires the current position of the vehicle 3 in the process of S2 in FIG. 7, the communication device 30 may acquire a 3D MAP in the vicinity of the moving path (prediction interval) moving in the LOS prediction period ΔT from the database 7 in advance. Furthermore, the communication device 30 may acquire real-time information to be added to the 3D MAP in the vicinity of the moving path (prediction interval) from the UE 2 connected to the network N1. Furthermore, the communication device 30 may acquire real-time information to be added to the 3D MAP in the vicinity of the moving path (prediction interval) from the UE 2 by a communication method called, for example, a side link or NR (New Radio)-V (Vehicle) 2X PC5. Furthermore, the communication device 30 may obtain real-time information to be added to the 3D MAP in the vicinity of the travel route (prediction section) from other vehicles connected to the network N1 or other vehicles connected by vehicle-to-vehicle communication. The vehicle-to-vehicle communication is, for example, by a side link or NR-V2X PC5. The real-time information is, for example, the presence of a crane temporarily installed for building construction work. The UE2 that provides the real-time information can be said to be a device that executes a sensing process.

[0074] Furthermore, the communication device 30 detects obstacles around the vehicle 3 and in front of the vehicle 3, which correspond to the position of the vehicle 3 at time k*ΔT (CX=CVx*Δt, CY=CVy*Δt), using a sensor 38 mounted on the vehicle 3. As described in Fig. 2, the sensor 38 is, for example, a radar, a camera, or a receiver that detects reflected waves from an obstacle of an electromagnetic wave emitted from the communication IF 33. That is, it can be said that the communication device 30 acquires, using the sensor 38, presence information on the presence range of the obstacle in space including the sending direction or the arriving direction of the radio wave during communication by the NTN communication unit 39.

[0075] Furthermore, the communication device 30 adds the information acquired from the UE 2 connected to the network N1 and the presence information of the obstruction detected by the sensor 38 to the 3D MAP acquired from the database 7. The order of the above S52, S53, and S54 is not limited, and any of them may be executed first. Also, the above S52, S53, and S54 may be executed in parallel.

[0076] Then, the communication device 30 calculates the LOS at the time k*ΔT (S55). The communication range in space is calculated from the information on obstructions detected by the sensor 38 and the like. Furthermore, the positions of the NTN wireless stations 6, etc. at time k*ΔT calculated in S53 are reflected in the communication range in space, and a connectable range (LOS) with the NTN wireless station 6 in the space above the vehicle 3 is calculated. The connectable range can also be said to be a range in which radio waves can be transmitted and received between the communication device 30 and the NTN wireless station 6.

[0077] Then, the communication device 30 reflects the LOS at the position corresponding to each time k*ΔT on the moving route (prediction interval) to the NTN cell (or footprint) on the moving route. That is, the communication device 30 limits the NTN cell (or footprint) of the NTN communication identified from the position of the NTN wireless station 6, etc., to the range of LOS defined by the presence of an obstruction. The range of LOS is, for example, the footprint FP1 to FP8 illustrated in FIG. 6.

[0078] Then, the communication device 30 judges whether or not LOOP3 is to be ended, that is, whether or not the repetition (k=0 to N) for each time interval Δt is completed (S58). If the repetition (k=0 to N) is not completed, the communication device 30 returns the process to S51. On the other hand, if the repetition (k=0 to N) is completed, the communication device 30 returns to the process of FIG. 7 (RETURN).

[0079] (Effects of the embodiment) As described above, according to this embodiment, the communication device 30 includes the NTN communication unit 39 connectable to a non-terrestrial network, the sensor 38 as a sensor unit, and the processor 31 and storage device 32 as a control unit.

[0080] The communication device 30 acquires presence information on the range of obstructions in space including the direction of transmission or direction of arrival of radio waves during communication by the NTN communication unit 39, using the sensor 38. The communication device 30 also identifies the LOS, which is the communication range in space above and in front of the vehicle 3 and which is estimated based on the acquired presence information and which can connect to the NTN radio station 6. Then, the communication device 30 executes processing based on the LOS. The processing based on the LOS is processing that minimizes interruption of the communication device 30, such as the processing from S7 to S9 in FIG. 7. That is, the communication device 30 can maintain communication with the network N1 as much as possible while executing communication by the NTN communication unit 39.

[0081] The communication device 30 is mounted on a moving object such as a vehicle 3. The communication device 30 estimates the LOS for each time interval Δt within a time period from the present time to a future time after a predetermined time ΔT has elapsed, from time to time, in accordance with the movement of the vehicle 3. The communication device 30 then executes either NTN communication or TN communication, or both, in accordance with the estimated LOS. That is, the communication device 30 can maintain communication with the network N1 as much as possible while moving by the vehicle 3.

[0082] The communication device 30 includes a communication IF 33 that is a TN communication unit that can be connected to a terrestrial network. The communication device 30 can receive the position or predicted position information of the NTN radio station 6 in space in advance via the terrestrial network. The communication device 30 then estimates the LOS by reflecting the position or predicted position information of the NTN radio station 6 received. The communication device 30 can stably acquire the position or predicted position information of the NTN radio station 6 in space and estimate the LOS by using the terrestrial network in addition to NTN communication.

[0083] In addition, the communication device 30 estimates the LOS based on information acquired from the UE 2, which is a device that executes the sensing process, or presence information acquired from the database 7 that accumulates information previously collected by the UE 2. Therefore, the 3D In addition to the MAP information (database 7 information), the LOS can be estimated based on information that changes over time. Also, the information obtained from UE2 includes real-time information. That is, the communication device 30 can estimate the LOS based on three-dimensional information that changes in real time, in addition to the 3D MAP information that is stored in the database 7 and that does not change much over time.

[0084] The communication device 30 switches between communication by the NTN communication unit 39 and communication by the communication IF 33 serving as the TN communication unit based on the estimation result. Therefore, the communication device 30 can stably communicate with the network N1 by the NTN communication unit 39 and the TN communication unit (communication IF 33). Moreover, the communication device 30 can achieve even more stable communication by using both the communication by the NTN communication unit 39 and the communication by the communication IF 33 serving as the TN communication unit. Moreover, the communication device 30 can continue and maintain communication with the network N1 while determining in advance the quality, connectivity, availability, etc. of the NTN communication.

[0085] The sensor 38 does not need to be a camera. Therefore, the vehicle 3 or the communication device 30 can acquire information to be added to the 3D MAP without mounting a camera. Furthermore, the communication device 30 can acquire information to be added to the 3D MAP without the sensor 38 by cooperating with another vehicle or the UE 2. However, whether the vehicle 3 is to mount the sensor 38 or a camera may be determined based on a trade-off between processing time, estimation accuracy, communication quality, and cost.

[0086] <Second embodiment> A communication device 30 according to the second embodiment will be described with reference to FIG. 9. In the above-described first embodiment, the communication device 30 judges whether or not a connection to an NTN wireless station 6 or the like continues and is maintained within the prediction interval. Then, if a connection to an NTN wireless station 6 or the like continues and is maintained within the prediction interval, the communication device 30 activates or maintains NTN communication. On the other hand, if a connection to an NTN wireless station 6 or the like is not maintained within the prediction interval, the communication device 30 activates TN communication such as cellular communication or wireless LAN communication. In this case, the communication device 30 uses both NTN communication and NT communication.

[0087] In this embodiment, in addition to the above processing, the communication device 30 determines a case where a connection to the NTN wireless station 6, etc. is completely impossible within the prediction interval. The processing of this embodiment other than the case where a connection to the NTN wireless station 6, etc. is completely impossible is the same as that of the first embodiment.

[0088] FIG. 9 is a flowchart illustrating the process of the communication device 30 of the second embodiment. In FIG. 9, the process from S1 to S6 is the same as that in FIG. 7, and therefore the description thereof is omitted. In this embodiment, after LOOP2 ends, the communication device 30 judges whether or not a connection to the NTN wireless station 6, etc. is impossible in the prediction interval (S11). If a connection to the NTN wireless station 6, etc. is impossible in the prediction interval (YES in S11), the communication device 30 activates the TN communication (S12). On the other hand, if a connection to the NTN wireless station 6, etc. is possible in the prediction interval (NO in S11), the communication device 30 judges whether or not a connection to the NTN wireless station 6 is maintained without interruption in the prediction interval (S13). Then, if a connection to the NTN wireless station 6 is maintained without interruption (YES in S13), the communication device 30 activates or maintains the NTN communication (S14). On the other hand, if the connection to the NTN wireless station 6 or the like is not maintained at least partially within the prediction interval (NO in S13), the communication device 30 uses both TN communication such as cellular communication or wireless LAN communication and NTN communication (S15). The process of S10 is the same as that in FIG. 7, and therefore the description will be omitted.

[0089] As described above, according to this embodiment, the communication device 30 judges whether NTN communication will be maintained completely without interruption within the prediction interval, whether it will be maintained partially, or whether it will not be maintained at all. Therefore, the communication device 30 can take early action in the case where NTN communication is not maintained completely. Furthermore, when NTN communication is partially maintained, the communication device 30 uses NTN communication to the extent possible, and when NTN communication is interrupted, quickly switches to TN communication. The process of S15 may simply be a process of enabling TN communication, similar to S9 in FIG.

[0090] <Third embodiment> Hereinafter, a communication device 30 according to the third embodiment will be described with reference to Fig. 10 and Fig. 11. In the first and second embodiments, the communication device 30 identifies an LOS, which is a communication range in which a connection can be made between the communication device 30 and the NTN wireless station 6, in the space around and in front of the vehicle 3. Then, the communication device 30 switches between NTN communication and TN communication, or uses both NTN communication and TN communication, depending on whether or not a connection with the NTN wireless station 6 is maintained within the prediction interval.

[0091] In this embodiment, a sensor 38 mounted on the vehicle 3 detects rainfall or the like in the range of the LOS, and the communication device 30 estimates the communication quality in the range of the LOS based on the detection result. Then, a processing example in which the communication device 30 switches between NTN communication and TN communication, or uses NTN communication and TN communication in combination, depending on the communication quality, is described. The processing of the third embodiment other than the detection of rainfall or the like in the range of the LOS, the estimation of communication quality in the range of the LOS, and the switching between NTN communication and TN communication in accordance with the communication quality, or the use of both, is the same as the first and second embodiments.

[0092] FIG. 10 is a flow chart illustrating the process of the communication device 30 of the third embodiment. In this process, the processes from S1 to S4, S6, and S7 are similar to those in FIG. 7 of the first embodiment, and therefore the description thereof is omitted. In this embodiment, before entering the repeated process of LOOP2, the communication device 30 acquires rainfall information in the sky within the prediction interval (S3A). For example, the communication device 30 acquires the rainfall information from a ground base station, a weather server connected to AF12 or DN5 (hereinafter, weather server, etc.).

[0093] In this embodiment, a weather server connected to the base station, AF12, or DN5 is connected to the radar rain gauge via the network N1 to detect the rainfall conditions. The radar rain gauge of this embodiment radiates electromagnetic waves in the terahertz band, that is, far-infrared light with a frequency of about 100 GHz to 10 THz and a wavelength of about 3 mm to 30 micrometers, into space. The radar rain gauge detects clouds, raindrops, precipitation, etc. from the reflection of the electromagnetic waves in the same configuration as a normal precipitation observation radar. The radar rain gauge may be installed in a ground base station, for example. The weather server may also obtain rainfall information from a computer of a public institution such as the Ministry of Construction or the Japan Meteorological Agency, or a computer of a private weather forecasting company, for example.

[0094] The structure of a radar rain gauge or precipitation observation radar is described, for example, in "The Structure and Operation of Radar Rain Gauges" by Kazuhiko Fukami, River Technology Training 2022, General Incorporated Foundation River Information Center (FRICS) (URL: http: / / www.river.or.jp / kougi2022_6.pdf, searched on October 15, 2023). However, in this document, the electromagnetic waves used are from the S band (wavelength 10 cm) to the X band (wavelength 3 m). On the other hand, the radar rain gauge of this embodiment transmits pulsed electromagnetic waves in the terahertz band into space, and measures the raindrop size distribution and rainfall amount from the power value and phase of the electromagnetic waves backscattered by rainclouds, raindrops, etc., or changes in polarization in the transmitted and received waves.

[0095] The weather server or the like then divides the sky above the travel route of the vehicle 3 into predetermined blocks, and calculates the amount of rainfall per unit time for each mesh. The mesh is, for example, a rectangle of predetermined dimensions (for example, a rectangle of 1 km by 10 km), and a reference point (for example, the position of one corner) is specified by latitude and longitude. However, the weather server or the like may add vertical height information to the mesh. In other words, the weather server or the like may measure the amount of rainfall within a predetermined height range. The communication device 30 determines the current position of the vehicle 3 and a predetermined time ΔT from the current time. The route to the destination after the movement is transferred to a weather server or the like, and the amount of rainfall in the mesh that overlaps with the route is obtained.

[0096] Then, in LOOP2, the communication device 30 calculates the LOS to the NTN wireless station 6 for each point and time in the moving direction, and further predicts the communication quality within the LOS range (S5A). The details of S5A will be described separately in detail with reference to FIG.

[0097] Then, in the determination of S7, if the connection to the NTN wireless station 6 or the like continues and is maintained within the prediction interval, the communication device 30 determines whether the communication quality in the LOS satisfies a standard (S7A). Here, the communication quality is determined based on whether or not a bit error rate estimated depending on weather such as rainfall exceeds a standard value.

[0098] Then, when the communication quality satisfies the standard in the entire range of the LOS, the communication device 30 activates or maintains the NTN communication (S8). On the other hand, when the communication quality does not satisfy the standard within the prediction interval, the communication device 30 activates the TN communication such as the cellular communication or the wireless LAN communication (S9). Note that in the process of S9, the communication device 30 may use both the TN communication and the NTN communication. The process of S10 is the same as that in FIG. 7, and therefore the description thereof will be omitted.

[0099] 11 is a flowchart illustrating the details of the LOS and communication quality prediction process (S5A in FIG. 10) of this embodiment. In this process, the processes from S51 to S55 are the same as those in FIG. 8 of the first embodiment, so the description thereof will be omitted.

[0100] In this embodiment, the communication device 30 calculates the LOS and then acquires the amount of rainfall in the range of the LOS (S56). That is, the communication device 30 identifies the meshes included in the range of the LOS among the meshes that overlap with the prediction interval on the travel route acquired in S5A of Fig. 10. Then, the communication device 30 estimates the communication quality in each mesh in the range of the LOS from the amount of rainfall in the meshes included in the range of the LOS (S57).

[0101] The communication device 30 has an attenuation value table that specifies the attenuation of electromagnetic waves for, for example, a transmission / reception frequency and an amount of rainfall. The communication device 30 refers to the attenuation value table and acquires the presence or absence of rainfall or the amount of rainfall in the NTN cell (or footprint) currently in communication. The communication device 30 also acquires the presence or absence of rainfall or the amount of rainfall in meshes that overlap with the prediction interval. Then, the communication device 30 refers to the attenuation value table based on the acquired amount of rainfall and specifies the communication quality in each mesh that overlaps with the prediction interval.

[0102] For example, the communication device 30 can assume that the communication quality Q0 measured in the NTN cell (or footprint) currently in communication reflects the amount of rainfall. Therefore, the communication device 30 obtains the difference ΔRxy between the amount of rainfall R0 in a mesh that overlaps the NTN cell currently in communication and the amount of rainfall Rxy in each mesh that overlaps each NTN cell on the prediction interval. Then, the communication device 30 obtains the communication quality in each mesh that overlaps each NTN cell on the prediction interval by correcting the current communication quality Q0 according to the difference Δ in the amount of rainfall, and reflects it in the communication quality in each NTN cell. Then, for example, the communication quality in the prediction interval on the moving route is stored in the storage device 32 or the like. However, the communication device 30 may store the maximum value, minimum value, average value, etc. of the communication quality in each mesh that overlaps with the prediction interval as the communication quality of each NTN cell that overlaps with the prediction interval in the storage device 32 or the like.

[0103] Instead of acquiring the amount of rainfall for each mesh, the communication device 30 may acquire the amount of rainfall for the entire predicted section on the travel route from a weather server or the like. That is, the communication device 30 may acquire an approximate value of the amount of rainfall and obtain the communication quality, assuming that the amount of rainfall for the entire predicted section on the travel route is constant with a predetermined allowable accuracy. The process of S58 is the same as that of FIG. 8, and therefore the explanation thereof will be omitted. The explanation is omitted.

[0104] As described above, the communication device 30 of the present embodiment estimates the LOS, which is the range in which radio waves can be transmitted and received, based on the rainfall conditions in the space. Therefore, the communication device 30 can estimate the LOS by taking into account not only the presence of obstacles but also the weather.

[0105] <Other embodiments> The above embodiment is merely an example, and the present disclosure may be modified as appropriate without departing from the spirit and scope of the present disclosure. Furthermore, the processes and means described in the present disclosure may be freely combined and implemented as long as no technical contradiction occurs.

[0106] Furthermore, a process described as being performed by one device may be shared and executed by multiple devices. Alternatively, a process described as being performed by different devices may be executed by one device. In a computer system, the hardware configuration (server configuration) by which each function is realized can be flexibly changed.

[0107] The present disclosure can also be realized by supplying a computer program implementing the functions described in the above embodiments to a computer, and having one or more processors of the computer read and execute the program. Such a computer program may be provided to the computer by a non-transitory computer-readable storage medium connectable to the system bus of the computer, or may be provided to the computer via a network. The non-transitory computer-readable storage medium may be, for example, any type of disk, such as a magnetic disk, a hard disk drive, an optical disk (CD (Compact Disc)-ROM (Read Only Memory)), a DVD (Digital Versatile Disc), a Blu-ray disk, etc.). , read-only memory (ROM), random access memory (RAM), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), magnetic cards, flash memory, The term "media" includes any type of medium suitable for storing electronic instructions, such as a hard disk drive or optical card. [Explanation of symbols]

[0108] 2. UE 3, 3A, 3B vehicle 4. Information processing equipment 5DN 6 NTN radio station 7 Database 11 NF 12AF 30 Communication Equipment 33 Communication Interface 38 Sensors 39 NTN Communications Department

Claims

1. An NTN communication unit connectable to a non-terrestrial network; A sensor unit; A control unit, The control unit acquires presence information regarding the range of obstructions in space, including the sending or arriving direction of radio waves during communication by the NTN communication unit, using the sensor unit, and performs processing based on the possible range in which the radio waves can be transmitted and received in the space between the NTN communication unit and the non-terrestrial network, which is estimated from the acquired presence information.

2. The communication device is mounted on a moving object, The communication device according to claim 1 , wherein the control unit estimates the possible range in a time interval from a current time point to a future time point after a predetermined time has elapsed, from moment to moment in response to movement of the mobile object.

3. Further comprising a TN communication unit connectable to a terrestrial network, The communication device according to claim 1 , wherein position or position prediction information of an NTN radio station in the space is received in advance via the terrestrial network, and the available range is estimated by reflecting the position or the position prediction information received in advance.

4. The communication device according to claim 1 , wherein the possible range is estimated based on the presence information acquired from a device that executes a sensing process or an information processing device that accumulates information previously collected by the device.

5. The communication apparatus according to claim 4 , wherein the possible range is estimated based on information acquired from the information processing apparatus and real-time information acquired from the device.

6. The communication device according to claim 3 , wherein the control unit switches between communication by the NTN communication unit and communication by the TN communication unit based on the estimated possible range.

7. The communication device according to claim 3 , wherein the control unit uses both communication by the NTN communication unit and communication by the TN communication unit.

8. The communication device according to claim 1 , wherein the control unit estimates the possible range based on a rainfall state in the space.

9. A communication system comprising the communication device according to claim 1 and the non-terrestrial network.

10. The computer A process of acquiring presence information regarding the range of an obstruction in space including the sending direction or the arriving direction of a radio wave during communication by an NTN communication unit connectable to a non-terrestrial network; A communication method which executes processing based on a possible range in which the radio waves can be transmitted and received between the NTN communication unit and the non-terrestrial network in the space, the range being estimated from the acquired presence information.

11. The NTN communication unit is mounted on a moving object, The communication method according to claim 10 , wherein the computer estimates the possible range in a time interval from a current time point to a future time point after a predetermined time has elapsed, from moment to moment in response to the movement of the mobile object.

12. The communication method according to claim 10, wherein position or position prediction information of an NTN radio station in the space is received in advance via a terrestrial network, and the possible range is estimated by reflecting the position or the position prediction information received in advance.

13. The communication method according to claim 10 , wherein the possible range is estimated based on the presence information acquired from a device that executes a sensing process or an information processing device that accumulates information previously collected by the device.

14. The communication method according to claim 13 , wherein the possible range is estimated based on information acquired from the information processing device and real-time information acquired from the device.

15. The communication method according to claim 12 , wherein communication by the NTN communication unit and communication by a TN communication unit connectable to the terrestrial network are switched based on the estimated possible range.

16. The communication method according to claim 12 , wherein communication by the NTN communication unit and communication by a TN communication unit connectable to the terrestrial network are used in combination.

17. The communication method according to claim 10 , wherein the possible range is estimated based on a rainfall state in the space.

18. On the computer, A process of acquiring presence information regarding the range of an obstruction in space including the sending direction or the arriving direction of a radio wave during communication by an NTN communication unit connectable to a non-terrestrial network; A program for executing processing based on the possible range in which the radio waves can be transmitted and received between the NTN communication unit and the non-terrestrial network in the space, which is estimated from the acquired presence information.

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