Terminal equipment, base station equipment, and communication methods

Abstract

To propose a mechanism that can further improve reliability outside coverage of a non-terrestrial network.SOLUTION: A terminal device disclosed herein performs satellite communication with a non-terrestrial base station. The terminal device includes a control unit. The control unit obtains non-terrestrial communication information for performing a non-satellite communication outside coverage of the non-terrestrial base station from the non-terrestrial base station. The control unit performs the non-satellite communication by using the non-terrestrial communication information when moving from an inside of the coverage to the outside of the coverage of the non-terrestrial base station.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The present disclosure relates to a terminal device, a base station device, and a communication method.

Background Art

[0002] Wireless access methods and wireless networks for cellular mobile communications (hereinafter also referred to as "Long Term Evolution (LTE)", "LTE-Advanced (LTE-A)", "LTE-Advanced Pro (LTE-A Pro)", "New Radio (NR)", "New Radio Access Technology (NRAT)", "Evolved Universal Terrestrial Radio Access (EUTRA)", or "Further EUTRA (FEUTRA)") are being studied in the 3rd Generation Partnership Project (3GPP (registered trademark)). In the following description, LTE includes LTE-A, LTE-A Pro, and EUTRA, and NR includes NRAT and FEUTRA. In LTE, the base station device (base station) is an eNodeB (evolved NodeB), in NR, the base station device (base station) is a gNodeB, and in LTE and NR, the terminal device (mobile station, mobile station device, terminal) is also referred to as a UE (User Equipment). LTE and NR are cellular communication systems in which a plurality of areas covered by a base station device are arranged in a cell shape. A single base station device may manage a plurality of cells.

[0003] NR is a Radio Access Technology (RAT) distinct from LTE, serving as a next-generation wireless access method. NR is an access technology capable of supporting various use cases, including Enhanced Mobile Broadband (eMBB), Massive Machine Type Communications (mMTC), and Ultra Reliable and Low Latency Communications (URLLC). NR can implement a technical framework that addresses the usage scenarios, requirements, and deployment scenarios in these use cases.

[0004] Furthermore, in the case of NR, due to increasing demands for wide-area coverage and connection stability, consideration has begun for non-terrestrial networks (NTN) that provide wireless networks from devices floating in the air or space. In non-terrestrial networks, wireless networks are provided to terminal equipment via satellite stations or aircraft. In addition, by using the same wireless access method as terrestrial networks, integrated operation between terrestrial and non-terrestrial networks becomes easier.

[0005] Non-terrestrial networks have wider coverage compared to terrestrial networks, making them highly effective for covering areas not covered by terrestrial networks. For example, one use case is V2X (Vehicle-to-X) communication. In V2X communication, communication errors can directly lead to accidents, requiring a higher level of reliability compared to other use cases. As mentioned earlier, in areas outside the coverage of terrestrial networks, non-terrestrial networks such as satellite communication can be used to provide communication coverage. Non-terrestrial networks have longer radio wave propagation distances compared to terrestrial networks, resulting in relatively poorer communication quality. Therefore, if communication between a base station and a terminal becomes beyond line of sight, it becomes difficult to continue communication. For example, if a car enters a tunnel, it is highly likely that communication with the non-terrestrial network will be lost. However, V2X communication is sometimes used for driving control, and unexpected communication interruptions pose a significant safety problem.

[0006] In relation to the discontinuous coverage environment of non-terrestrial networks, Non-Patent Document 1 examines technologies for achieving power saving in IoT (Internet of Things) terminals in the context of communication between IoT terminals and satellite communications in the discontinuous coverage environment of non-terrestrial networks. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] R2-2110834, Ericsson, “Discontinuous coverage in IoT NTN”, 3GPP TSG-RAN WG2 Meeting #116-e E-meeting, 1-12 November 2021, [Online], [Searched on April 13, 2020], Internet<https: / / www.3gpp.org / ftp / TSG_RAN / WG2_RL2 / TSGR2_116-e / Docs / R2-2110843.zip> [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] Non-patent document 1 discusses studies aimed at reducing power consumption in IoT terminals in non-terrestrial network discontinuous coverage environments. However, non-patent document 1 does not consider improving reliability outside of non-terrestrial network coverage. Therefore, in use cases where reliability is required, such as V2X communication, there is a need for technologies aimed at improving reliability in non-terrestrial network discontinuous coverage environments.

[0009] Therefore, this disclosure proposes a mechanism that can further improve reliability outside the coverage area of ​​non-terrestrial networks.

[0010] It should be noted that the above-mentioned problems or objectives are merely one of several problems or objectives that can be solved or achieved by the multiple embodiments disclosed herein. [Means for solving the problem]

[0011] The terminal device of this disclosure performs satellite communication with a non-terrestrial base station device. The terminal device includes a control unit. The control unit obtains non-satellite communication information from the non-terrestrial base station device for performing non-satellite communication outside the coverage of the non-terrestrial base station device. When the control unit moves from within the coverage of the non-terrestrial base station device to outside the coverage, it performs the non-satellite communication using the non-satellite communication information. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows an example configuration of a communication system according to the embodiment of this disclosure. [Figure 2] This figure shows an example of a wireless network provided by a communication system. [Figure 3] This diagram shows an overview of the satellite communications provided by the communication system. [Figure 4]It is a diagram showing an example of a cell formed by a non-stationary satellite. [Figure 5] It is a diagram showing a configuration example of a management device according to an embodiment of the present disclosure. [Figure 6] It is a diagram showing a configuration example of a ground station according to an embodiment of the present disclosure. [Figure 7] It is a diagram showing a configuration example of a satellite station according to an embodiment of the present disclosure. [Figure 8] It is a diagram showing a configuration example of a terminal device according to an embodiment of the present disclosure. [Figure 9] It is a sequence diagram for explaining an example of the handover process. [Figure 10] It is a sequence diagram for explaining another example of the handover process. [Figure 11] It is a diagram for explaining an example of a first case of a communication system according to an embodiment of the present disclosure. [Figure 12] It is a diagram for explaining another example of a first case of a communication system according to an embodiment of the present disclosure. [Figure 13] It is a diagram for explaining another example of a first case of a communication system according to an embodiment of the present disclosure. [Figure 14] It is a diagram for explaining an example of communication by a communication system according to an embodiment of the present disclosure. [Figure 15] It is a sequence diagram showing an example of the flow of terminal information notification processing according to an embodiment of the present disclosure. [Figure 16] It is a sequence diagram showing another example of the flow of terminal information notification processing according to an embodiment of the present disclosure. [Figure 17] It is a sequence diagram showing an example of the flow of handover processing according to an embodiment of the present disclosure. [Figure 18] It is a diagram for explaining another example of communication by a communication system according to an embodiment of the present disclosure. [Figure 19] It is a diagram for explaining an example of a second case of a communication system according to an embodiment of the present disclosure. [Figure 20]It is a sequence diagram showing an example of the flow of movement processing according to an embodiment of the present disclosure. [Figure 21] It is a diagram for explaining another example of the second case of the communication system according to an embodiment of the present disclosure. [Figure 22] It is a sequence diagram showing an example of the flow of movement processing according to an embodiment of the present disclosure.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0014] Also, in the present specification and drawings, a plurality of components having substantially the same functional configuration may be distinguished by attaching different numbers or alphabets after the same reference numeral. For example, a plurality of configurations having substantially the same functional configuration are distinguished as terminal devices 401, 402, and 403 as necessary. However, when it is not necessary to particularly distinguish each of a plurality of components having substantially the same functional configuration, only the same reference numeral is attached. For example, when it is not necessary to particularly distinguish the terminal devices 401, 402, and 403, they are simply referred to as the terminal device 40.

[0015] Also, in the present specification and drawings, specific values may be shown for explanation, but the values are examples, and other values may be applied.

[0016] Furthermore, resources in this specification and in the drawings represent Frequency, Time, Resource Element (including REG, CCE, and CORESET), Resource Block, Bandwidth Part, Component Carrier, Symbol, Sub-Symbol, Slot, Mini-Slot, Subslot, Subframe, Frame, PRACH occasion, Occasion, Code, Multi-access physical resource, Multi-access signature, Subcarrier Spacing (Numerology), and the like.

[0017] The one or more embodiments (including examples and modifications) described below can each be implemented independently. On the other hand, at least some of the embodiments described below may be implemented in appropriate combination with at least some of the other embodiments. These embodiments may contain novel features that differ from each other. Therefore, these embodiments may contribute to solving different objectives or problems and may produce different effects.

[0018] <<1. Overview>> Radio Access Technologies (RATs) such as LTE (Long Term Evolution) and NR (New Radio) are being considered by 3GPP (registered trademark). LTE and NR are types of cellular communication technologies that enable mobile communication of terminal devices by arranging multiple base stations in a cell-like structure. In this case, a single base station may manage multiple cells.

[0019] In the following explanation, "LTE" includes LTE-A (LTE-Advanced), LTE-A Pro (LTE-Advanced Pro), and EUTRA (Evolved Universal Terrestrial Radio Access). Similarly, "NR" includes NRAT (New Radio Access Technology) and FEUTRA (Further EUTRA). A single base station may manage multiple cells. In the following explanation, cells supporting LTE are referred to as LTE cells, and cells supporting NR are referred to as NR cells.

[0020] NR is the next generation (fifth generation) of radio access technology (RAT) after LTE. NR is a radio access technology that can support a variety of use cases, including eMBB (Enhanced Mobile Broadband), mMTC (Massive Machine Type Communications), and URLLC (Ultra-Reliable and Low Latency Communications). NR is being developed with the aim of creating a technical framework that addresses the usage scenarios, requirements, and deployment scenarios in these use cases.

[0021] Furthermore, in NR, due to increasing demands for wide-area coverage and connection stability, consideration has begun for non-terrestrial networks. In non-terrestrial networks, wireless networks are planned to be provided to terminal equipment via base stations other than ground stations, such as satellite stations and aircraft stations. These base stations other than ground stations are called non-terrestrial stations or non-terrestrial base stations. Wireless networks provided by ground stations are called terrestrial networks (TN). By using the same wireless access method for terrestrial and non-terrestrial networks, integrated operation of terrestrial and non-terrestrial networks becomes possible.

[0022] As mentioned above, in V2X communication, for example, communication errors can directly lead to accidents, so highly reliable communication is required compared to other use cases. As mentioned above, in areas outside the coverage of terrestrial networks, communication coverage can be provided by non-terrestrial networks such as satellite communication.

[0023] On the other hand, non-terrestrial networks have longer radio wave propagation distances compared to terrestrial networks, resulting in relatively poorer communication quality. Therefore, if communication between a non-terrestrial base station and a terminal becomes beyond line of sight, it becomes difficult to continue communication. For example, if a car enters a tunnel, there is a high probability that it will be unable to continue communication with the non-terrestrial network. However, V2X communication is sometimes used for driving control, and unexpected communication interruptions pose a major safety problem.

[0024] Therefore, in use cases where reliability is required, such as V2X communication, there is a need for technologies aimed at improving reliability in discontinuous coverage environments of non-terrestrial networks.

[0025] Therefore, in this embodiment, this requirement is resolved by the following means.

[0026] For example, the terminal device of this embodiment is a terminal device that performs satellite communication with a non-terrestrial base station device. The terminal device obtains non-satellite communication information from the non-terrestrial base station device for performing non-satellite communication outside the coverage of the non-terrestrial base station device. When the terminal device moves from inside to outside the coverage of the non-terrestrial base station device, it performs non-satellite communication using the non-satellite communication information.

[0027] This allows terminal devices to smoothly conduct non-satellite communications outside the coverage area of ​​non-terrestrial base station equipment. As a result, terminal devices can further improve the reliability of communications in discontinuous coverage environments of non-terrestrial networks.

[0028] Having outlined the basics of this embodiment, the communication system according to this embodiment will now be described in detail.

[0029] <<2. Communication System Configuration>> Communication System 1 is a Bent-pipe (Transparent) type mobile satellite communication system. Communication System 1 is a cellular communication system using radio access technologies such as LTE and NR, and provides wireless communication to ground terminal equipment via satellite stations. The radio access method used by Communication System 1 is not limited to LTE and NR, but may also be other radio access methods such as W-CDMA (Wideband Code Division Multiple Access) and cdma2000 (Code Division Multiple Access 2000).

[0030] The configuration of communication system 1 will be described in detail below.

[0031] <2.1. Overall Configuration of the Communication System> Figure 1 shows an example configuration of a communication system 1 according to an embodiment of the present disclosure. The communication system 1 comprises a management device 10, a ground station 20, a satellite station 30, and a terminal device 40. The communication system 1 provides a wireless network capable of mobile communication to a user through the coordinated operation of each wireless communication device constituting the communication system 1. The wireless network in this embodiment is composed of, for example, a wireless access network and a core network. In this embodiment, a wireless communication device is a device having wireless communication functionality, and in the example of Figure 1, this refers to the ground station 20, the satellite station 30, and the terminal device 40.

[0032] The communication system 1 may include multiple management devices 10, ground stations 20, satellite stations 30, and terminal devices 40. In the example in Figure 1, the communication system 1 includes management devices 101, 102, etc. as the management device 10, and ground stations 201, 202, etc. as the ground stations 20. The communication system 1 also includes satellite stations 301, 302, etc. as the satellite stations 30, and terminal devices 401, 402, 403, etc. as the terminal devices 40.

[0033] Figure 2 shows an example of a wireless network provided by communication system 1. The ground station 20 (satellite station 30) and base station 60 constitute a cell. A cell is an area covered by wireless communication. A cell may be a macrocell, microcell, femtocell, or small cell. Communication system 1 may be configured to manage multiple cells with a single base station (satellite station), or it may be configured to manage one cell with multiple base stations.

[0034] In the example shown in Figure 2, base stations 601 and 602 constitute terrestrial network TN1, and base stations 603, 604, and 605 constitute terrestrial network TN2. Terrestrial network TN1 and terrestrial network TN2 are networks operated by wireless communication carriers, such as telephone companies. Terrestrial network TN1 and terrestrial network TN2 may be operated by different wireless communication carriers or by the same wireless communication carrier. It is also possible to consider terrestrial network TN1 and terrestrial network TN2 as a single terrestrial network.

[0035] Terrestrial networks TN1 and TN2 are each connected to a core network. In the example in Figure 2, base station 60, which constitutes terrestrial network TN2, is connected to core network CN, which is configured by, for example, a management device 101. If the wireless access method of terrestrial network TN2 is LTE, then core network CN is EPC. If the wireless access method of terrestrial network TN2 is NR, then core network CN is 5GC. Of course, core network CN is not limited to EPC or 5GC, and may be a core network of another wireless access method. In the example in Figure 2, terrestrial network TN1 is not connected to a core network, but terrestrial network TN1 may be connected to core network CN. Also, terrestrial network TN1 may be connected to a core network that is not shown and is different from core network CN.

[0036] The core network CN is equipped with gateway devices and gateway switches, and is connected to the public network PN via the gateway devices. The public network PN is a public data network such as the Internet, a regional IP network, or a telephone network (mobile phone network, fixed telephone network, etc.). The gateway device is a server device connected to the Internet or a regional IP network, for example. The gateway switch is a switch connected to a telephone company's telephone network, for example. The management device 101 may also function as a gateway device or gateway switch.

[0037] The satellite stations 30, 50, and aircraft station 70 shown in Figure 2 are all non-terrestrial stations such as satellite stations and aircraft stations. A group of satellite stations (or satellite stations) that constitute a non-terrestrial network is called a Spaceborne Platform. Similarly, a group of aircraft stations (or aircraft stations) that constitute a non-terrestrial network is called an Airborne Platform. In the example in Figure 2, satellite stations 301, 302, and 303 constitute Spaceborne Platform SBP1, satellite station 501 constitutes Spaceborne Platform SBP2, and aircraft station 703 constitutes Airborne Platform ABP1.

[0038] Terminal device 40 can communicate with both ground stations and non-ground stations. In the example in Figure 2, terminal device 401 can communicate with ground stations that constitute the terrestrial network TN1. Terminal device 401 can also communicate with non-ground stations that constitute the spacebone platforms SBP1 and SBP2. Furthermore, terminal device 401 can also communicate with non-ground stations that constitute the airbone platform ABP1. Terminal device 401 may also be able to communicate directly with other terminal devices 40 (terminal device 402 in the example in Figure 2). In addition, terminal device 403 can communicate with non-ground stations that constitute the spacebone platform SBP1.

[0039] Non-terrestrial stations such as satellite station 30 may be connected to a terrestrial network or core network via a relay station. Non-terrestrial stations can also communicate directly with each other without using a relay station.

[0040] Relay stations include, for example, aeronautical stations and earth stations. An aeronautical station is a radio station installed on the ground or on a mobile device moving on the ground in order to communicate with an aircraft station. An earth station is a radio station located on Earth (including in the air) in order to communicate with a satellite station (space station). An earth station may be a large earth station or a small earth station such as a VSAT (Very Small Aperture Terminal). An earth station may be a VSAT control earth station (also called a master station or HUB station) or a VSAT earth station (also called a slave station). An earth station may also be a radio station installed on a mobile device moving on the ground. For example, an earth station on board a ship is called an Earth Station on board Vessels (ESV). An earth station may also include an aircraft earth station installed on an aircraft (including a helicopter) that communicates with a satellite station. An earth station may also include an aeronautical earth station installed on a mobile device moving on the ground that communicates with an aircraft earth station via a satellite station. The relay station may also be a portable radio station that communicates with satellite stations or aircraft stations. The relay station can be considered as part of communication system 1.

[0041] Each component of the Spacebone Platforms SBP1 and SBP2 communicates with the terminal device 40 via satellite. Satellite communication refers to wireless communication between a satellite station and a communication device. Figure 3 shows an overview of the satellite communication provided by the communication system 1. Satellite stations are mainly divided into geostationary satellite stations and low Earth orbit satellite stations.

[0042] A geostationary satellite station is located at an altitude of approximately 35,786 km and revolves around the Earth at the same speed as the Earth's rotation. In the example shown in Figure 3, satellite station 501, which is part of the Spacebone Platform SBP2, is a geostationary satellite station. The geostationary satellite station has a relative velocity of almost zero with respect to the ground-based terminal equipment 40, and is observed as stationary from the ground-based terminal equipment 40. Satellite station 501 communicates with terminal equipment 401, 403, 404, etc., located on Earth.

[0043] Low Earth orbit (LEG) satellite stations are satellite stations that orbit at lower altitudes compared to geostationary and medium Earth orbit (MEG) satellite stations. LEG satellite stations are, for example, satellite stations located between 500 km and 2000 km in altitude. In the example shown in Figure 3, satellite station 30 is part of the Space Bone Platform SBP1. 2、 303 is a low Earth orbit satellite station. Note that Figure 3 only shows two satellite stations, 302 and 303, as constituting the Space Bone Platform SBP1. However, in reality, the Space Bone Platform SBP1 is composed of two or more (e.g., tens to thousands) satellite stations 30, forming a low Earth orbit satellite constellation. Unlike geostationary satellite stations, low Earth orbit satellite stations have a relative velocity with respect to ground terminal equipment 40 and are observed as moving from the ground terminal equipment 40. Satellite station 30 2、 Each of the 303 units constitutes a cell and communicates via satellite with terminal devices 401, 403, 404, etc., located on Earth.

[0044] Figure 4 shows an example of a cell formed by a non-geostationary satellite. Figure 4 shows cell C2 formed by satellite station 302, which is a low Earth orbit satellite station. Satellite stations orbiting in low Earth orbit communicate with ground terminal equipment 40 with a predetermined directionality. For example, the angle R1 shown in Figure 4 is 40°. In the case of Figure 4, the radius D1 of cell C2 formed by satellite station 302 is, for example, 1000 km. Low Earth orbit satellite stations move at a constant speed. If it becomes difficult for a low Earth orbit satellite station to provide satellite communication to ground terminal equipment 40, a subsequent low Earth orbit satellite station (neighbor satellite station) will provide satellite communication. In the example of Figure 4, if satellite station 302 becomes unable to provide satellite communication to ground terminal equipment 40, a subsequent satellite station 303 will provide satellite communication. Note that the values ​​of angle R1 and radius D1 described above are merely examples and are not limited to those shown.

[0045] As mentioned above, medium Earth orbit and low Earth orbit satellites move in orbit at very high speeds. For example, a low Earth orbit satellite at an altitude of 600 km moves in orbit at a speed of 7.6 km / s. Low Earth orbit satellites form cells (or beams) on the ground with a radius of several tens to several hundreds of kilometers. As the satellite moves, the cells formed on the ground also move, so a handover may be necessary even if the ground terminal equipment 40 is not moving. For example, if we assume a case where the diameter of the cell formed on the ground is 50 km and the ground terminal equipment 40 is not moving, a handover will occur in approximately 6 to 7 seconds.

[0046] As described above, terminal device 40 is capable of wireless communication using a non-terrestrial network. Furthermore, the satellite station 30 of communication system 1 constitutes a non-terrestrial network. This allows communication system 1 to extend its services to terminal devices 40 located in areas not covered by the terrestrial network. For example, communication system 1 can provide public safety communications and critical communications to communication devices such as IoT (Internet of Things) devices and MTC (Machine Type Communications) devices. Additionally, by using a non-terrestrial network, service reliability and recoverability are improved, allowing communication system 1 to reduce service vulnerability to physical attacks or natural disasters. Communication system 1 can also provide service connections to aircraft terminal devices such as airplane passengers and drones, as well as mobile terminal devices such as ships and trains. Moreover, communication system 1 can provide A / V content, group communications, IoT broadcast services, software download services, and highly efficient multicast and broadcast services such as emergency messages. Furthermore, communication system 1 can also perform traffic offloading between the terrestrial network and the non-terrestrial network. To achieve these goals, it is desirable that the non-terrestrial network provided by communication system 1 be operationally integrated with the terrestrial network provided by communication system 1 at a higher layer. Furthermore, it is desirable that the non-terrestrial network provided by communication system 1 share the same wireless access method as the terrestrial network provided by communication system 1.

[0047] It should be noted that the devices in the diagram can be considered as devices in a logical sense. In other words, some of the devices in the diagram may be implemented as virtual machines (VMs), containers, Docker, etc., and these may be implemented on the same physical hardware.

[0048] Furthermore, in this embodiment, a ground station can be referred to as a base station. A satellite station can be referred to as a relay station. If a satellite station has the functionality of a base station, then a satellite station can be referred to as a base station.

[0049] Furthermore, LTE base stations are sometimes referred to as eNodeB (Evolved Node B) or eNB. Similarly, NR base stations are sometimes referred to as gNodeB or gNB. In addition, in both LTE and NR, terminal equipment 40 (also called a mobile station or terminal) is sometimes referred to as UE (User Equipment). Terminal equipment 40 is a type of communication device and is also called a mobile station or terminal.

[0050] In this embodiment, the concept of a communication device includes not only portable mobile devices such as handheld terminals (terminal devices 40), but also devices installed on structures or mobile objects. Structures or mobile objects themselves may also be considered communication devices. Furthermore, the concept of a communication device includes not only terminal devices 40, but also base stations and relay devices. A communication device is a type of processing device and information processing device. A communication device can also be referred to as a transmitting device or a receiving device.

[0051] The configuration of each device constituting communication system 1 will be described in detail below. Note that the configurations of each device shown below are merely examples. The configuration of each device may differ from those shown below.

[0052] <2.2. Configuration of the control device> Next, the configuration of the control device 10 will be described.

[0053] The management device 10 is a device that manages the wireless network. For example, the management device 10 is a device that manages the communications of the ground station 20. If the core network is EPC, then the management device 10 is a device that functions as, for example, an MME (Mobility Management Entity). If the core network is 5GC, then the management device 10 is a device that functions as, for example, an AMF (Access and Mobility Management Function) and / or an SMF (Session Management Function). Of course, the functions of the management device 10 are not limited to MME, AMF, and SMF. For example, if the core network is 5GC, the management device 10 may be a device that functions as an NSSF (Network Slice Selection Function), AUSF (Authentication Server Function), and UDM (Unified Data Management). Also, the management device 10 may be a device that functions as an HSS (Home Subscriber Server).

[0054] Furthermore, the management device 10 may also have gateway functionality. For example, if the core network is EPC, the management device 10 may have S-GW (Serving Gateway) or P-GW (Packet Data Network Gateway) functionality. Also, if the core network is 5GC, the management device 10 may have UPF (User Plane Function) functionality. Furthermore, the management device 10 does not necessarily have to be a device that constitutes the core network. For example, suppose the core network is a W-CDMA (Wideband Code Division Multiple Access) or cdma2000 (Code Division Multiple Access 2000) core network. In this case, the management device 10 may be a device that functions as an RNC (Radio Network Controller).

[0055] Figure 5 shows an example configuration of a management device 10 according to an embodiment of the present disclosure. The management device 10 comprises a communication unit 11, a storage unit 12, and a control unit 13. Note that the configuration shown in Figure 5 is a functional configuration, and the hardware configuration may differ. Furthermore, the functions of the management device 10 may be distributed and implemented across multiple physically separated configurations. For example, the management device 10 may be composed of multiple server devices.

[0056] The communication unit 11 is a communication interface for communicating with other devices. The communication unit 11 may be a network interface or an equipment connection interface. For example, the communication unit 11 may be a LAN (Local Area Network) interface such as a NIC (Network Interface Card), or a USB interface consisting of a USB (Universal Serial Bus) host controller, USB port, etc. Furthermore, the communication unit 11 may be a wired interface or a wireless interface. The communication unit 11 functions as a communication means for the management device 10. The communication unit 11 communicates with the ground station 20, etc., according to the control of the control unit 13.

[0057] The memory unit 12 is a data read / write storage device such as DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), flash memory, or hard disk. The memory unit 12 functions as a storage means for the management device 10. For example, the memory unit 12 stores the connection status of the terminal device 40. For example, the memory unit 12 stores the RRC status and ECM status of the terminal device 40. The memory unit 12 may also function as a home memory that stores the location information of the terminal device 40.

[0058] The control unit 13 is a controller that controls each part of the management device 10. The control unit 13 is implemented by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). For example, the control unit 13 is implemented by the processor executing various programs stored in the internal storage device of the management device 10 using RAM (Random Access Memory) or the like as a working area. The control unit 13 may also be implemented by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). A CPU, MPU, ASIC, and FPGA can all be considered as controllers.

[0059] <2.3. Ground Station Configuration> Next, I will explain the configuration of the ground station 20.

[0060] The ground station 20 is a wireless communication device that communicates wirelessly with the terminal device 40 via the satellite station 30. However, the ground station 20 may be configured to communicate with the terminal device 40 without going through the satellite station 30.

[0061] The ground station 20 is a type of communication device. More specifically, the ground station 20 is a device equivalent to a radio base station (Node B, eNB, gNB, etc.) or a radio access point. The ground station 20 may also be a radio relay station. The ground station 20 may also be an optical extension device called an RRH (Remote Radio Head). The ground station 20 may also be a receiving station such as an FPU (Field Pickup Unit). The ground station 20 may also be an IAB (Integrated Access and Backhaul) donor node or IAB relay node that provides radio access lines and radio backhaul lines using time division multiplexing, frequency division multiplexing, or spatial division multiplexing.

[0062] The wireless access technology used by the ground station 20 may be cellular communication technology or wireless LAN technology. Of course, the wireless access technology used by the ground station 20 is not limited to these and may be other wireless access technologies. For example, the wireless access technology used by the ground station 20 may be LPWA communication technology. Of course, the wireless communication used by the ground station 20 may be wireless communication using millimeter waves. Furthermore, the wireless communication used by the ground station 20 may be wireless communication using radio waves, or wireless communication using infrared or visible light (optical wireless).

[0063] The ground station 20 may be capable of NOMA (Non-Orthogonal Multiple Access) communication with the terminal device 40. Here, NOMA communication refers to communication (transmission, reception, or both) using non-orthogonal resources. The ground station 20 may also be capable of NOMA communication with other ground stations 20.

[0064] Furthermore, the ground stations 20 may be able to communicate with each other via a base station-core network interface (e.g., S1 Interface). This interface may be either wired or wireless. Also, the base stations may be able to communicate with each other via inter-base station interfaces (e.g., X2 Interface, S1 Interface). This interface may be either wired or wireless.

[0065] Furthermore, the concept of a base station (also called a base station) includes not only donor base stations but also relay base stations (also called relay stations or relay stations). Additionally, the concept of a base station includes not only structures equipped with base station functions but also equipment installed within those structures.

[0066] Structures include buildings such as skyscrapers, houses, transmission towers, train stations, airports, ports, and stadiums. The concept of structures also includes not only buildings, but also non-building structures such as tunnels, bridges, dams, walls, and steel columns, as well as equipment such as cranes, gates, and wind turbines. Furthermore, the concept of structures includes not only structures on land (in the narrow sense of the ground) or underground, but also structures on water such as piers and megafloats, and underwater structures such as oceanographic observation equipment. A base station can be rephrased as an information processing device.

[0067] The ground station 20 may be a donor station or a relay station. Furthermore, the ground station 20 may be a fixed station or a mobile station. A mobile station is a wireless communication device configured to be mobile (e.g., a base station). In this case, the ground station 20 may be a device installed on a mobile device or the mobile device itself. For example, a relay station with mobility can be considered a ground station 20 as a mobile station. Also, devices that are inherently mobile, such as vehicles, drones, and smartphones, and that incorporate base station functions (or at least some base station functions), qualify as ground stations 20 as mobile stations.

[0068] Here, the moving object may be a mobile device such as a smartphone or mobile phone. Furthermore, the moving object may be a moving object that moves on land (on the ground in the narrow sense) (for example, a car, bicycle, bus, truck, motorcycle, train, maglev train, etc.) or a moving object that moves underground (for example, inside a tunnel) (for example, a subway).

[0069] Furthermore, the mobile object may be a mobile object that moves on the water (for example, a passenger ship, cargo ship, hovercraft, or other vessel) or a mobile object that moves underwater (for example, a submersible, submarine, or unmanned underwater vehicle).

[0070] Furthermore, the moving object may be a moving object that moves within the atmosphere (for example, an aircraft such as an airplane, airship, or drone).

[0071] Furthermore, the ground station 20 may be a ground base station (ground station) installed on the ground. For example, the ground station 20 may be a base station located on a structure on the ground, or a base station installed on a mobile body moving on the ground. More specifically, the ground station 20 may be an antenna installed on a structure such as a building and a signal processing device connected to that antenna. Of course, the ground station 20 may be the structure or mobile body itself. "Ground" refers to the ground in a broad sense, including not only land (ground in the narrow sense) but also underground, on water, and underwater. Note that the ground station 20 is not limited to a ground base station. For example, the ground station 20 may be an aircraft station. From the perspective of the satellite station 30, an aircraft station located on Earth can also be considered a ground station.

[0072] An aircraft station is a radio communication device capable of floating within the atmosphere, such as an aircraft. An aircraft station may be a device mounted on an aircraft, or it may be the aircraft itself. The concept of an aircraft includes not only heavy aircraft such as airplanes and gliders, but also light aircraft such as balloons and airships. Furthermore, the concept of an aircraft includes not only heavy and light aircraft, but also rotary-wing aircraft such as helicopters and autogyros. An aircraft station (or the aircraft on which an aircraft station is mounted) may also be an unmanned aerial vehicle such as a drone.

[0073] The concept of unmanned aerial vehicles (UAS) also includes unmanned aircraft systems (UAS) and tethered UAS. Furthermore, the concept of unmanned aerial vehicles includes lighter than air UAS (LTA) and heavier than air UAS (HTA). In addition, the concept of unmanned aerial vehicles also includes high-altitude UAS platforms (HAPs).

[0074] The coverage size of the ground station 20 can range from large, like a macrocell, to small, like a picocell. Of course, the coverage size of the ground station 20 can also be extremely small, like a femtocell. Furthermore, the ground station 20 may have beamforming capabilities. In this case, the ground station 20 may form cells or service areas for each beam.

[0075] Figure 6 shows an example configuration of a ground station 20 according to the present disclosure. The ground station 20 comprises a wireless communication unit 21, a storage unit 22, and a control unit 23. Note that the configuration shown in Figure 6 is a functional configuration, and the hardware configuration may differ. Furthermore, the functions of the ground station 20 may be distributed and implemented across multiple physically separated configurations.

[0076] The wireless communication unit 21 is a signal processing unit for wireless communication with other wireless communication devices (e.g., terminal device 40). The wireless communication unit 21 operates according to the control of the control unit 23. The wireless communication unit 21 supports one or more wireless access methods. For example, the wireless communication unit 21 supports both NR and LTE. In addition to NR and LTE, the wireless communication unit 21 may also support W-CDMA and cdma2000. Furthermore, the wireless communication unit 21 may support automatic retransmission technologies such as HARQ (Hybrid Automatic Repeat reQuest).

[0077] The wireless communication unit 21 includes a receiving processing unit 211, a transmitting processing unit 212, and an antenna 213. The wireless communication unit 21 may include multiple receiving processing units 211, transmitting processing units 212, and antennas 213. When the wireless communication unit 21 supports multiple wireless access methods, each part of the wireless communication unit 21 may be configured individually for each wireless access method. For example, the receiving processing unit 211 and the transmitting processing unit 212 may be configured individually for LTE and NR. The antenna 213 may also be composed of multiple antenna elements (e.g., multiple patch antennas). In this case, the wireless communication unit 21 may be configured to be beamforming capable. The wireless communication unit 21 may be configured to enable polarization beamforming using vertical polarization (V polarization) and horizontal polarization (H polarization).

[0078] The receiving processing unit 211 processes the uplink signal received via the antenna 213. For example, the receiving processing unit 211 performs down-conversion, removal of unwanted frequency components, amplification level control, quadrature demodulation, conversion to a digital signal, removal of guard intervals (cyclic prefixes), and extraction of frequency domain signals using the Fast Fourier Transform on the uplink signal. Then, the receiving processing unit 211 separates the uplink channel and uplink reference signal, such as PUSCH (Physical Uplink Shared Channel) and PUCCH (Physical Uplink Control Channel), from the processed signal. The receiving processing unit 211 also demodulates the received signal using modulation schemes such as BPSK (Binary Phase Shift Keying) and QPSK (Quadrature Phase Shift Keying) for the modulation symbols of the uplink channel. The modulation scheme used for demodulation may be 16QAM (Quadrature Amplitude Modulation), 64QAM, or 256QAM. In this case, the signal points on the constellation do not necessarily need to be equidistant. The constellation may be a non-uniform constellation (NUC). The receiving processing unit 211 then performs decoding on the encoded bits of the demodulated uplink channel. The decoded uplink data and uplink control information are output to the control unit 23.

[0079] The transmission processing unit 212 performs the transmission processing of downlink control information and downlink data. For example, the transmission processing unit 212 encodes the downlink control information and downlink data input from the control unit 23 using encoding methods such as block coding, convolutional coding, and turbo coding. Then, the transmission processing unit 212 modulates the encoded bits using a predetermined modulation method such as BPSK, QPSK, 16QAM, 64QAM, or 256QAM. In this case, the signal points on the constellation do not necessarily have to be equidistant. The constellation may be a non-uniform constellation. Then, the transmission processing unit 212 multiplexes the modulation symbols and downlink reference signals for each channel and places them in predetermined resource elements. Then, the transmission processing unit 212 performs various signal processing on the multiplexed signals. For example, the transmission processing unit 212 performs processing such as conversion to the time domain using the Fast Fourier Transform, addition of guard intervals (cyclic prefixes), generation of baseband digital signals, conversion to analog signals, quadrature modulation, upconversion, removal of extraneous frequency components, and power amplification. The signal generated by the transmission processing unit 212 is transmitted from the antenna 213.

[0080] Antenna 213 is an antenna device (antenna unit) that converts electric current and radio waves to each other. Antenna 213 may consist of one antenna element (for example, one patch antenna) or multiple antenna elements (for example, multiple patch antennas). If antenna 213 consists of multiple antenna elements, the wireless communication unit 21 may be configured to beamforming. For example, the wireless communication unit 21 may be configured to generate a directional beam by controlling the directivity of the wireless signal using multiple antenna elements. Antenna 213 may also be a dual-polarization antenna. If antenna 213 is a dual-polarization antenna, the wireless communication unit 21 may use vertical polarization (V polarization) and horizontal polarization (H polarization) when transmitting the wireless signal. The wireless communication unit 21 may then control the directivity of the transmitted wireless signal using vertical polarization and horizontal polarization.

[0081] The memory unit 22 is a data read / write storage device such as DRAM, SRAM, flash memory, or hard disk. The memory unit 22 functions as a storage means for the ground station 20.

[0082] The control unit 23 is a controller that controls various parts of the ground station 20. The control unit 23 is implemented by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). For example, the control unit 23 is implemented by the processor executing various programs stored in the storage device inside the ground station 20 using RAM (Random Access Memory) or the like as a working area. The control unit 23 may also be implemented by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). CPUs, MPUs, ASICs, and FPGAs can all be considered controllers.

[0083] Furthermore, the base station 60 is a device that communicates with the terminal device 40 without going through the satellite station 30, and can be configured in the same way as the ground station 20.

[0084] <2.4. Satellite Station Configuration> Next, we will explain the configuration of satellite station 30.

[0085] The satellite station 30 is a relay station that relays communication between the ground station 20 and the terminal device 40. The satellite station 30 may also be a base station that provides base station functions to the terminal device 40.

[0086] Satellite station 30 is a radio communication device capable of floating outside the atmosphere. Satellite station 30 may be a device mounted on a space mobile vehicle such as an artificial satellite, or it may be the space mobile vehicle itself. A space mobile vehicle is a mobile vehicle that moves outside the atmosphere. Examples of space mobile vehicles include artificial satellites, spacecraft, space stations, probes, and other artificial celestial bodies.

[0087] The satellite that becomes satellite station 30 may be a low Earth orbit (LEO), medium Earth orbit (MEO), geostationary Earth orbit (GEO), or highly elliptical orbit (HEO) satellite. Of course, the satellite station may also be equipment mounted on a low Earth orbit satellite, medium Earth orbit satellite, geostationary satellite, or highly elliptical orbit satellite.

[0088] Figure 7 shows an example configuration of a satellite station 30 according to the embodiment of this disclosure. The satellite station 30 comprises a wireless communication unit 31, a storage unit 32, and a control unit 33. Note that the configuration shown in Figure 7 is a functional configuration, and the hardware configuration may differ. Furthermore, the functions of the satellite station 30 may be distributed and implemented across multiple physically separated configurations.

[0089] The wireless communication unit 31 is a wireless communication interface that communicates wirelessly with other wireless communication devices (e.g., a ground station 20, a terminal device 40, a satellite station 50, and other satellite stations 30). The wireless communication unit 31 supports one or more wireless access methods. For example, the wireless communication unit 31 supports both NR and LTE. In addition to NR and LTE, the wireless communication unit 31 may also support W-CDMA and cdma3000. The wireless communication unit 31 comprises a receiving processing unit 311, a transmitting processing unit 312, and an antenna 313. The wireless communication unit 31 may have multiple receiving processing units 311, transmitting processing units 312, and antennas 313. When the wireless communication unit 31 supports multiple wireless access methods, each part of the wireless communication unit 31 may be configured individually for each wireless access method. For example, the receiving processing unit 311 and the transmitting processing unit 312 may be configured individually for LTE and NR. The configurations of the receiving processing unit 311, the transmitting processing unit 312, and the antenna 313 are the same as those described above. The wireless communication unit 31 may also be configured to be beamforming, similar to the wireless communication unit 21.

[0090] The memory unit 32 is a data read / write storage device such as DRAM, SRAM, flash memory, or hard disk. The memory unit 32 functions as a storage means for the satellite station 30.

[0091] The control unit 33 is a controller that controls various parts of the satellite station 30. The control unit 33 is implemented by a processor such as a CPU or MPU. For example, the control unit 33 is implemented by the processor executing various programs stored in the internal memory of the satellite station 30 using RAM or the like as a working area. The control unit 33 may also be implemented by an integrated circuit such as an ASIC or FPGA. A CPU, MPU, ASIC, and FPGA can all be considered as controllers.

[0092] <2.5. Terminal Device Configuration> Next, the configuration of the terminal device 40 will be described.

[0093] Terminal device 40 is a wireless communication device that communicates wirelessly with other communication devices such as ground stations 20, satellite stations 30 and 50, base stations 60, and aircraft stations 70. Terminal device 40 may be, for example, a mobile phone, a smart device (smartphone or tablet), a PDA (Personal Digital Assistant), or a personal computer. Alternatively, terminal device 40 may be a professional camera equipped with communication functions, or a motorcycle or mobile relay vehicle equipped with communication equipment such as an FPU (Field Pickup Unit). Furthermore, terminal device 40 may be an M2M (Machine to Machine) device or an IoT (Internet of Things) device.

[0094] The terminal device 40 may be capable of NOMA communication with the ground station 20. Furthermore, the terminal device 40 may use automatic retransmission technology such as HARQ when communicating with the ground station 20. The terminal device 40 may be capable of sidelink communication with other terminal devices 40. The terminal device 40 may also use automatic retransmission technology such as HARQ when performing sidelink communication. Furthermore, the terminal device 40 may be capable of NOMA communication even when communicating with other terminal devices 40 (sidelink). Furthermore, the terminal device 40 may be capable of LPWA communication with other communication devices (for example, the ground station 20 and other terminal devices 40). Furthermore, the wireless communication used by the terminal device 40 may be millimeter-wave wireless communication. Furthermore, the wireless communication used by the terminal device 40 (including sidelink communication) may be radio wave wireless communication, or infrared or visible light wireless communication (optical wireless).

[0095] Furthermore, the terminal device 40 may be a mobile device. The mobile device is a portable wireless communication device. In this case, the terminal device 40 may be a wireless communication device installed on the mobile device, or it may be the mobile device itself. For example, the terminal device 40 may be a vehicle that moves on roads, such as an automobile, bus, truck, or motorcycle, or a wireless communication device mounted on such a vehicle. The mobile device may be a mobile terminal, or it may be a mobile device that moves on land (ground in the narrow sense), underground, on water, or underwater. The mobile device may also be a mobile device that moves within the atmosphere, such as a drone or helicopter, or a mobile device that moves outside the atmosphere, such as an artificial satellite.

[0096] The terminal device 40 may simultaneously connect to and communicate with multiple base stations or multiple cells. For example, if one base station supports a communication area via multiple cells (e.g., pCell, sCell), it is possible to combine these multiple cells using carrier aggregation (CA), dual connectivity (DC), or multi-connectivity (MC) technologies to enable communication between the ground station 20 and the terminal device 40. Alternatively, the terminal device 40 can communicate with multiple ground stations 20 via cells of different ground stations 20 using coordinated multi-point transmission and reception (CoMP) technology.

[0097] Figure 8 shows an example configuration of a terminal device 40 according to the present disclosure. The terminal device 40 comprises a wireless communication unit 41, a storage unit 42, and a control unit 43. Note that the configuration shown in Figure 8 is a functional configuration, and the hardware configuration may differ. Furthermore, the functions of the terminal device 40 may be implemented in a distributed manner across multiple physically separated configurations.

[0098] The wireless communication unit 41 is a signal processing unit for wireless communication with other wireless communication devices (e.g., the ground station 20 and other terminal devices 40). The wireless communication unit 41 operates according to the control of the control unit 43. The wireless communication unit 41 comprises a receiving processing unit 411, a transmitting processing unit 412, and an antenna 413. The configuration of the wireless communication unit 41, the receiving processing unit 411, the transmitting processing unit 412, and the antenna 413 may be the same as that of the wireless communication unit 21, the receiving processing unit 211, the transmitting processing unit 212, and the antenna 213 of the ground station 20. Also, the wireless communication unit 41 may be configured to be beamforming, similar to the wireless communication unit 21.

[0099] The memory unit 42 is a data read / write storage device such as DRAM, SRAM, flash memory, or hard disk. The memory unit 42 functions as a storage means for the terminal device 40.

[0100] The control unit 43 is a controller that controls various parts of the terminal device 40. The control unit 43 is implemented by a processor such as a CPU or MPU. For example, the control unit 43 is implemented by the processor executing various programs stored in the memory device inside the terminal device 40 using RAM or the like as a working area. The control unit 43 may also be implemented by an integrated circuit such as an ASIC or FPGA. A CPU, MPU, ASIC, and FPGA can all be considered as controllers.

[0101] <<3. Handover via Satellite Communications>> Next, we will explain the handover between satellite stations 30. Applying handover technology to satellite communications is effective in terms of enabling smooth inter-cell movement of terminal equipment 40.

[0102] Here, we will explain an example of a handover using Figure 9. Figure 9 is a sequence diagram illustrating an example of the handover process. Figure 9 shows the case where terminal device 40 hands over from the Source cell of the Source base station device, which is the handover source, to the Target cell of the Target base station device, which is the handover destination.

[0103] As shown in Figure 9, the terminal device 40 performs a measurement and sends a measurement report to the Source base station device (step S101). Similarly, the terminal device 40 performs a measurement and sends a measurement report to the Target base station device (step S102).

[0104] Based on the measurement report, the Source base station device determines whether a handover of the terminal device 40 is necessary (step S103). If the Source base station device determines that a handover is necessary, it requests a handover from the Target base station device (step S104).

[0105] When the Target base station device receives a handover request, it performs admission control (step S105) and notifies the Source base station device of the acknowledgment for the handover request (step S106).

[0106] Next, the Source base station device sends an RRC Reconfiguration including a handover command to the terminal device 40 (step S107) to notify it that a handover is to be performed.

[0107] When terminal device 40 receives RRC Reconfiguration, it detaches from the Source cell of the Source base station device (step S108) and performs the initial access procedure with the Target base station device. For example, terminal device 40 sends PRACH (Physical Random Access Channel) to the Target base station device (step S109). The Target base station device sends a Random Access response to terminal device 40 (step S110). When terminal device 40 sends a Random Access response to the Target base station device (step S111), the initial access procedure is completed and the handover process is completed.

[0108] Here, we have shown the case where the terminal device 40 performs a two-step random access procedure (2-step RACH) as the initial access procedure, but the procedure is not limited to this. The terminal device 40 may also perform a four-step random access procedure (4-step RACH) as the initial access procedure.

[0109] As shown in Figure 9, in the handover, the terminal device 40 initiates the handover when it receives a handover command from the Source base station device.

[0110] Another example of handover is a conditional handover, in which the Source base station device notifies the terminal device 40 in advance of information about potential handover destinations. Figure 10 is a sequence diagram illustrating another example of the handover flow. Figure 10 shows the case where the terminal device 40 selects either the first or second Target base station device, which are candidates for the handover destination, and performs the handover. The first Target base station device has Target candidate cell #1, and the second Target base station device has Target candidate cell #2.

[0111] As shown in Figure 10, the terminal device 40 performs the measurement and sends the measurement report to the Source base station device (step S201).

[0112] Based on the measurement report, the Source base station device determines whether a conditional handover of the terminal device 40 is required (step S202). If the Source base station device determines that a conditional handover is required, it requests a handover from the first Target base station device (step S203) and from the second Target base station device (step S204).

[0113] The first Target base station device performs admission control upon receiving a handover request (step S205). Similarly, the second Target base station device performs admission control upon receiving a handover request (step S206). The first Target base station device notifies the Source base station device of its acknowledgment regarding the handover request (step S207). The second Target base station device notifies the Source base station device of its acknowledgment regarding the handover request (step S208).

[0114] Next, the Source base station device transmits an RRC Reconfiguration to the terminal device 40 (step S209). The RRC Reconfiguration includes, for example, information about the first and second Target base station devices which are candidates for handover destinations, and information about the trigger for performing a conditional handover.

[0115] When terminal device 40 receives RRC Reconfiguration, it transmits RRC Reconfiguration complete to Source base station device (step S210) and evaluates the trigger for performing a Conditional handover (step S211). When terminal device 40 evaluates the trigger and detects the trigger (step S212), it detaches from Source cell (Source base station device) (step S213) and starts the initial connection procedure with the handover destination base station. In Figure 10, it is assumed that the first Target base station device is detected as the handover destination base station.

[0116] As shown in Figure 10, the terminal device 40 performs an initial connection procedure with the first Target base station device. The initial connection procedure is the same as the procedure shown in Figure 9.

[0117] Having completed the initial connection procedure and connected with the terminal device 40, the first Target base station device notifies the Source base station device of Handover Success, indicating that the handover was successful (step S214). Upon receiving Handover Success, the Source base station device cancels the handover to the second Target base station device by notifying the second Target base station device, which was not selected as the handover destination, of Handover Cancel (step S215).

[0118] Thus, in a conditional handover, the Source base station device does not determine the Target base station device to which the handover will occur, but rather notifies the terminal device 40 of the candidate Target base station devices. This allows the terminal device 40 to select a Target base station device that is available for connection at the time of the handover and perform the handover.

[0119] Furthermore, in a conditional handover, in order to achieve a seamless handover, the terminal device 40 detects the trigger for performing a conditional handover in step S212 of Figure 10, for example, and then detaches from the source base station device in the next step S213. In other words, in order to avoid a period during which communication with all source base station devices and target base station device candidates becomes impossible, and a period during which initial connection cannot be performed, the terminal device 40 detects the trigger for performing a conditional handover in step S212 of Figure 10, for example, and then detaches from the source base station device in the next step S213.

[0120] In the following explanation, the satellite station 30 can be replaced with non-terrestrial base station equipment that operates as a communication device, such as a drone, balloon, or airplane. Furthermore, in communications referred to as transparent payload or vent pipe, the base station equipment may represent a terrestrial base station that communicates via the satellite equipment. Moreover, this technology is not limited to these examples, and can also be applied to communications between terrestrial base station equipment and terminal equipment 40.

[0121] Furthermore, in the following explanation, satellite station 30 may be simply referred to as base station equipment (Source base station equipment, Target base station equipment, etc.).

[0122] <<4. Technical Features>> The above describes the handover of satellite station 30. Next, the operation of communication system 1 will be described. As mentioned above, the communication system 1 of this disclosure aims to continue communication when communication between satellite station 30 and terminal device 40 becomes beyond line of sight.

[0123] Here, several cases can be considered in which communication between the satellite station 30 and the terminal device 40 becomes non-line of sight, such as when communication becomes non-line of sight due to obstacles such as clouds or tunnels, or when the coverage of multiple satellite stations 30 does not overlap. Therefore, the operation of the communication system 1 will be explained below for each case.

[0124] In the following explanation, it is assumed that V2X communication is performed in communication system 1, but the scope of application of the technology disclosed herein is not limited to V2X communication. For example, the technology disclosed herein may also be applicable when high-speed, high-capacity communication, voice communication, or IoT communication is performed in communication system 1.

[0125] Furthermore, in the following explanation, when referring to ground-based base station equipment, it will be clearly indicated as "ground-based base station equipment 60". When simply referred to as "base station equipment," it is assumed to refer to non-ground base station equipment, including satellite stations 30, etc.

[0126] Furthermore, as described above, the base station equipment may include base station equipment that performs communications referred to as transparent payloads or vent pipes, etc., which are communicated via satellite equipment.

[0127] For the sake of simplicity, in the following explanation, the base station equipment (non-terrestrial base station equipment) will be considered to be the satellite station 30, and the satellite station 30 will also be referred to as the base station equipment 30. Furthermore, it will be assumed that the coverage of the base station equipment is formed by the cells formed by the satellite station 30.

[0128] <4.1. Case 1> First, as the first case, we will describe the case in which the coverage of multiple base station devices 30 does not overlap. Figure 11 is a diagram illustrating an example of the first case of the communication system 1 according to the embodiment of this disclosure.

[0129] In the example shown in Figure 11, multiple base station devices 301 and 302 each form coverage areas C31 and C32. The base station devices 301 and 302 communicate with terminal devices 40 within coverage areas C31 and C32 (satellite communication or non-terrestrial network communication).

[0130] As shown in Figure 11, coverage areas C31 and C32 do not overlap, and there is an area 90 that is outside the coverage area C3 of the base station equipment 30. In area 90, satellite communication with the base station equipment 30 is not possible.

[0131] Here, if the terminal device 40 is a mobile device (for example, a vehicle), as it moves, the terminal device 40 may move from the coverage area C31 of the base station device 301 to the area 90 outside of coverage area C31. Also, as it moves, the terminal device 40 may move from the area 90 outside of coverage area C31 of the base station device 301 to the coverage area C32 of the base station device 302.

[0132] Thus, when the terminal device 40 moves from within coverage C3 of the base station device 30 to outside coverage C3, it is required that the communication of the terminal device 40 be continued. Furthermore, when the terminal device 40 moves from outside coverage C3 of the base station device 30 to within coverage C3, it is required that the communication of the terminal device 40 be continued.

[0133] Note that the case in which there is an area 90 outside of coverage C3 between coverage C31 and C32 of multiple base station devices 301 and 302 is not limited to the example in Figure 11.

[0134] Figure 12 is a diagram illustrating another example of the first case of the communication system 1 according to the embodiment of this disclosure.

[0135] In the example shown in Figure 12, the coverage areas C31 and C32 of base station devices 301 and 302 are adjacent (or overlapping), but an obstacle 80 (clouds in the example in Figure 12) creates an area 90 that is outside the coverage areas C31 and C32 of base station devices 301 and 302. In area 90, terminal device 40 cannot communicate with base station device 30 via satellite. Note that obstacle 80 is not limited to natural objects such as clouds. For example, structures such as tunnels can also be obstacles 80.

[0136] Thus, even if the coverage C31 and C32 of base station devices 301 and 302 are adjacent (or overlapping), there are cases where, due to the influence of obstacles 80, there is an area 90 in which the terminal device 40 cannot communicate with the base station device 30.

[0137] Furthermore, the number of base station devices 30 is not limited to two. For example, even if there are three or more base station devices 30, there may be areas 90 in which terminal devices 40 cannot communicate with the base station devices 30.

[0138] Figure 13 is a diagram illustrating another example of the first case of the communication system 1 according to the embodiment of this disclosure.

[0139] Figure 13 shows the case where there are three base station devices 30. Base station devices 301 and 302 communicate (satellite communication) with terminal devices 40 within coverage C31 and C32. However, base station device 303 cannot communicate (satellite communication) with terminal devices 40 due to an obstacle 80 (cloud in the example of Figure 13). Thus, there are cases where an area 90 outside the coverage C3 of base station device 303 is created due to an obstacle 80.

[0140] As described above, when the terminal device 40 moves from within coverage C3 of the base station device 30 to outside coverage C3, it is required that the communication of the terminal device 40 be continued. Similarly, when the terminal device 40 moves from outside coverage C3 of the base station device 30 to within coverage C3, it is required that the communication of the terminal device 40 be continued.

[0141] Therefore, in the embodiments of this disclosure, when the terminal device 40 moves from within the coverage C3 of the base station device 30 to outside the coverage C3, it continues communication by performing non-satellite communication. Also, when the terminal device 40 moves from outside the coverage C3 of the base station device 30 to inside the coverage C3, it continues communication by performing satellite communication.

[0142] Non-satellite communications include terrestrial communications between the ground base station equipment 60 and the terminal equipment 40, and side-link communications between the terminal equipment 40.

[0143] <4.1.1. When communication is continued via terrestrial communication> Figure 14 is a diagram illustrating an example of communication by the communication system 1 according to the embodiment of this disclosure. In Figure 14, the terminal device 40 performs ground communication with the ground base station device 60 outside the coverage C3 of the base station device 30.

[0144] As shown in Figure 14, when the terminal device 40 is located within the coverage C31 of the base station device 301, it communicates with the base station device 301 via satellite. At this time, the base station device 301 can collect terminal information from the terminal device 40. The base station device 301 uses this terminal information to determine, for example, when the terminal device 40 moves outside the coverage C31 of the base station device 301.

[0145] When the terminal device 40 moves from within coverage C31 of the base station device 301 to area 90 outside coverage C31, the terminal device 40 communicates with the ground base station device 60. The communication between the terminal device 40 and the ground base station device 60 is non-satellite communication conducted via a terrestrial network. In this way, the terminal device 40 can ensure highly reliable communication by performing a handover from the base station device 301 to the ground base station device 60.

[0146] At this time, the terminal device 40 uses non-satellite communication information obtained from the base station device 301 to perform non-satellite communication with the ground base station device 60. For example, the terminal device 40 uses the non-satellite communication information to perform a handover from the base station device 301 to the ground base station device 60 (also referred to as the first handover). Note that the handover shown in Figure 9 or the conditional handover shown in Figure 10 may be applied as this handover.

[0147] The terminal device 40 may, for example, perform a first handover on a timer basis. In this case, the base station device 301 sets a timer for the terminal device 40 until the first handover is performed. The terminal device 40 starts the first handover procedure when the timer expires.

[0148] Alternatively, the terminal device 40 may determine the timing for the first handover based on its own location information and the orbital information of the satellite (base station device 301). The terminal device 40 may determine the timing for the first handover based on its own location information and the orbital information of the satellite. Alternatively, the terminal device 40 may perform the first handover in accordance with trigger information regarding the timing of the first handover provided by the base station device 301.

[0149] This allows the terminal device 40 to perform a smoother handover from the base station device 301 to the ground base station device 60, thereby ensuring more reliable communication.

[0150] Furthermore, when terminal device 40 moves from outside the coverage C31 of base station device 301 to within the coverage C32 of base station device 302, it performs satellite communication with base station device 302, which is different from base station device 301. In this way, terminal device 40 can ensure highly reliable communication by performing a handover from ground base station device 60 to base station device 302.

[0151] At this time, the terminal device 40 uses satellite communication information obtained from the base station device 301 and / or the ground base station device 60 to communicate with the base station device 302 via satellite. For example, the terminal device 40 uses the satellite communication information to perform a handover from the ground base station device 60 to the base station device 302 (hereinafter also referred to as the second handover). Note that the handover shown in Figure 9 or the conditional handover shown in Figure 10 may be applied as this handover.

[0152] The terminal device 40 may, for example, perform a second handover on a timer basis. In this case, the base station device 301 and / or the ground base station device 60 set a timer for the terminal device 40 until the second handover is performed. The terminal device 40 starts the second handover procedure when the timer expires.

[0153] Alternatively, terminal device 40 may determine the timing for a second handover based on its own location information and the orbital information of the satellite (base station device 302). Alternatively, terminal device 40 may perform the first handover in accordance with trigger information regarding the timing of the second handover provided by base station device 301 and / or ground base station device 60.

[0154] This allows the terminal device 40 to perform a smoother handover from the ground base station device 60 to the base station device 302, thereby ensuring more reliable communication.

[0155] In the first case shown in Figure 14, the base station equipment (satellite station) 30 to which the terminal device 40 connects differs before it enters the non-terrestrial communication coverage area and after it leaves the non-terrestrial communication coverage area. As shown in Figure 14, the terminal device 40 connects to base station equipment 301 in coverage area C31, and connects to base station equipment 302 in coverage area C32.

[0156] Thus, the base station equipment (satellite station) 30 to which the terminal device 40 connects may differ before it enters non-terrestrial communication coverage and after it leaves non-terrestrial communication coverage. In such cases, information including at least one of the signaling information (e.g., non-satellite communication information) described later may be shared between the base station equipment 30.

[0157] In other words, base station device 301 can notify base station device 302 of information including at least one of the signaling information described later. For example, base station device 301 may notify base station device 302 of information regarding the handover procedure to the Target cell and information regarding the handover trigger to the Target cell, which will be described later.

[0158] This allows the terminal device 40 to perform a smoother handover.

[0159] Furthermore, by sharing information (an example of inter-satellite information) between base station devices 301 and 302, the terminal device 40 can perform a transparent handover. Here, a transparent handover is a means by which the terminal device 40 can resume communication with base station device 30 without being aware of whether the connected base station device 30 is the same or different before entering and after leaving non-terrestrial communication coverage. By performing a transparent handover, the terminal device 40 can resume satellite communication without being aware of whether the connected base station device 30 is the same or different from the perspective of the terminal device 40.

[0160] In this case, the base station device 30 does not need to notify the terminal device 40 of information regarding the handover (for example, first HO (Handover) information and / or second HO information). For example, the base station device 30 and the terminal device 40 can perform communication including a handover in the same manner as in the second case described later.

[0161] [Signaling example] The following describes an example of signaling information used in communication in the first case.

[0162] (Device information) The terminal device 40 may, for example, notify the base station device 30 of information regarding its movement outside the non-terrestrial communication coverage as terminal information. This terminal information may be notified, for example, before the terminal device 40 moves from within the coverage C3 of the base station device 30 to outside the coverage C3, that is, from within the non-terrestrial communication coverage area to outside the non-terrestrial communication coverage area.

[0163] The device information may include at least one of the following pieces of information: • Location information, such as the location information of the terminal device 40. • Information related to mobility, such as speed and direction of movement of the terminal device 40. • Sensing information from terminal device 40 • Information regarding the terminal status of terminal device 40

[0164] The sensing information of the terminal device 40 may include, for example, information about obstacles such as tunnels and clouds, location information and mobility information of other terminal devices 40 in the vicinity, weather information, and information about ambient brightness.

[0165] Information regarding the terminal status of the terminal device 40 may include, for example, the capabilities of the terminal device 40, information on the fuel and battery levels of the terminal device 40, accident history information of the terminal device 40, temperature information of the terminal device 40, and inspection history information of the terminal device 40.

[0166] If the terminal device 40 is able to communicate with the base station device 30, for example, by being located within the coverage C3 of the base station device 30, it can notify the base station device 30 of terminal information at any time.

[0167] For example, terminal device 40 may notify terminal information when it receives a request (a request to notify information) from base station device 30. That is, terminal device 40 notifies base station device 30 of terminal information in response to a request from base station device 30. Alternatively, terminal device 40 may notify base station device 30 of terminal information at a predetermined periodic interval (semi-persistent interval).

[0168] (Non-satellite communications information) Non-satellite communication information is signaling information used for movement from within coverage C3 of the base station equipment 30 to outside coverage C3, that is, from within the non-terrestrial communication coverage area to outside the non-terrestrial communication coverage area. Non-satellite communication information is notified from the base station equipment 30 to the terminal equipment 40.

[0169] Non-satellite communication information may include, for example, first HO information regarding the implementation of a first handover, or first trigger information regarding a trigger for moving outside of non-terrestrial communication coverage.

[0170] (First HO information) The first HO information includes, for example, information regarding the implementation of a first handover to the ground base station equipment 60. The first HO information may also include information regarding the implementation of a handover from the ground base station equipment 60 to the base station equipment 30 (the second handover described above).

[0171] The first HO information may include at least one of the following pieces of information: • Information regarding the handover procedure to the target cell • Information regarding triggers for handover to target cell • Information regarding detaching from the source cell • Information on the next handover destination

[0172] Information regarding the handover procedure to the Target cell is, for example, information regarding the first handover procedure to the Target cell (ground base station equipment 60). This information may include at least one of the following pieces of information: • Target cell's PRACH (Physical Random Access Channel) transmission resources • Preamble sequence for sending PRACH from target cell • Target cell's cell ID • Target cell's Uplink / Downlink carrier frequency • Target Cell bandwidth • Terminal-specific ID after handover (C-RNTI (Cell-Radio Network Temporary ID)) • Radio Resource Configuration after Handover Conditions for updating the handover information set • Trigger information for performing a handover • Target cell timing advanced information • SSB index of the target cell • Information regarding transmission weights • Information regarding 2-STEP initial access

[0173] Information regarding the trigger for performing a handover to the Target cell (ground base station equipment 60) may include, for example, the following: • RSRP (Reference Signal Received Power) information of target cell candidates • RSRQ (Reference Signal Received Quality) information for target cell candidates • RSSI (Received Signal Strength Indication) information of target cell candidates • Timer information regarding the handover of target cell candidates • Information regarding the start time of the handover process for target cell candidates. • Information regarding the start time of the trigger detection operation for the handover of candidate target cells. • Information regarding the behavior after the timer for performing a Target cell candidate handover expires. • Behavior when a synchronization signal is received from a cell other than the target cell candidate.

[0174] Information regarding the detachment from the source cell (base station device 30) may include at least one piece of information such as the following: • Source cell's RSRP information • Source cell RSRQ information • RSSI information of the source cell • Information regarding the timer that performs detachment from the source cell. • Information regarding the time when detachment from the source cell is performed. • Information regarding the execution of detachment from source cell

[0175] Information about subsequent handover destinations may be notified from base station device 301 to terminal device 40 in addition to the information about the next handover destination (e.g., ground base station device 60). Information about subsequent handover destinations may be the same as the first HO information, except that the Target cell is the next handover destination (e.g., base station device 302) and the Source cell is the next handover destination (e.g., ground base station device 60). Furthermore, information about subsequent handover destinations may include information about the timing of consecutive handovers.

[0176] (First trigger information) As described above, non-satellite communication information may include, for example, first trigger information relating to a trigger for moving outside of non-terrestrial communication coverage. The base station device 30 may notify the terminal device 40 of the first trigger information in advance. When the terminal device 40 receives the first trigger information, it performs a move outside of non-terrestrial communication coverage based on the first trigger information.

[0177] The first trigger information may include at least one piece of information such as the following: • Threshold information regarding the received power of non-terrestrial communication cells (within non-terrestrial communication coverage) (e.g., RSRP threshold information, RSRQ threshold information, RSSI threshold information, etc.) • Information regarding the timer used to move from within non-terrestrial communication coverage to outside non-terrestrial communication coverage. • Information regarding the time of movement from within non-terrestrial communication coverage to outside non-terrestrial communication coverage. • Information regarding the execution of movement from within non-terrestrial communications coverage to outside non-terrestrial communications coverage.

[0178] (Satellite communications information) Satellite communication information is signaling information used for movement from outside coverage C3 of base station equipment 30 to inside coverage C3, that is, from outside the non-terrestrial communication coverage area to inside the non-terrestrial communication coverage area. Satellite communication information is notified to terminal equipment 40 from base station equipment 30 and / or terrestrial base station equipment 60.

[0179] Satellite communication information may include, for example, second HO information regarding the implementation of a second handover, or second trigger information regarding a trigger for moving into non-terrestrial communication coverage.

[0180] (Second HO information) The second HO information includes, for example, information regarding the implementation of a second handover to base station equipment 302. The second HO information may include information similar to the first HO information, except that the Target cell is, for example, base station equipment 302 and the Source cell is, for example, ground base station equipment 60.

[0181] (Second trigger information) The second trigger information may include, for example, information regarding a trigger for moving into non-terrestrial communication coverage. The base station equipment 30 and / or the ground base station equipment 60 may notify the terminal equipment 40 of the second trigger information in advance. When the terminal equipment 40 receives the second trigger information, it performs a move into non-terrestrial communication coverage based on the second trigger information.

[0182] The second trigger information may include at least one piece of information such as the following: • RSRP threshold information for terrestrial communication cells • RSRQ threshold information for terrestrial communication cells • RSSI threshold information for terrestrial communication cells • Information regarding the timer that enables movement from outside non-terrestrial communication coverage to inside non-terrestrial communication coverage. • Information regarding the time of movement from outside non-terrestrial communication coverage to inside non-terrestrial communication coverage. • Information regarding the execution of movement from outside non-terrestrial communications coverage to inside non-terrestrial communications coverage.

[0183] (Second terminal information) The terminal device 40 may, for example, notify the base station device 30 and / or the ground base station device 60 of information regarding its movement into the non-terrestrial communication coverage as second terminal information. This second terminal information may be notified, for example, before the terminal device 40 moves from outside the coverage C3 of the base station device 30 to inside the coverage C3, i.e., from outside the non-terrestrial communication coverage area to inside the non-terrestrial communication coverage area.

[0184] The second terminal information may include, for example, information similar to the terminal information described above. The terminal device 40 may, for example, notify the base station device 30 and / or the ground base station device 60 of the second terminal information at any time if it is able to communicate with the base station device 30 and / or the ground base station device 60.

[0185] For example, terminal device 40 may notify second terminal information at the time it receives a request (request for information notification) from base station device 30 or / and ground base station device 60. That is, terminal device 40 notifies base station device 30 or / and ground base station device 60 of terminal information in response to a request from base station device 30 or / and ground base station device 60. Alternatively, terminal device 40 may notify base station device 30 or / and ground base station device 60 of second terminal information at a predetermined periodic interval (semi-persistent interval).

[0186] [Example of communication processing] The following describes an example of communication processing when communication system 1 continues communication by performing terrestrial communication outside of non-terrestrial communication coverage. Note that the communication processing example described below is just one example, and other processing may be performed in communication system 1 according to the embodiment of this disclosure.

[0187] (Notification processing) Figure 15 is a sequence diagram showing an example of the flow of terminal information notification processing according to the embodiment of this disclosure. The notification processing shown in Figure 15 is performed between the terminal device 40 and the base station device 30 within non-terrestrial communication coverage.

[0188] The base station device 30 transmits a synchronization signal and system information to the terminal device 40 (step S301). The system information may include an explicit notice for performing communication according to the embodiments of this disclosure.

[0189] Next, the base station device 30 performs a Random Access Procedure with the terminal device 40 (step S302). At this time, the terminal device 40 may notify the base station device 30 of information data such as its own device information and sensing information.

[0190] The terminal device 40 notifies the base station device 30 of its terminal capability (step S303). The terminal capability may include capabilities relating to communication according to the embodiments of this disclosure (e.g., a first handover and / or a second handover). That is, the terminal capability may include information indicating, for example, whether or not a first handover and / or a second handover can be performed.

[0191] The base station device 30 notifies the terminal device 40 of quasi-static control information (step S304). This control information may include information relating to communication according to the embodiment of this disclosure.

[0192] The base station device 30 notifies the terminal device 40 of downlink control information (step S305). This control information may include information related to communication according to the embodiment of this disclosure, such as DCI (Downlink Control Information).

[0193] The base station device 30 transmits downlink data to the terminal device 40 (step S306). The base station device 30 transmits downlink data using, for example, PDSCH (Physical Downlink Shared Channel).

[0194] When terminal device 40 receives downlink data, it notifies base station device 30 of information regarding retransmission control (step S307). Information regarding retransmission control may include, for example, ACK / NACK.

[0195] Here, assume that terminal information (information data such as terminal information and sensing information) is generated in the terminal device 40 (step S308).

[0196] In this case, terminal device 40 sends a scheduling request to base station device 30 (step S309).

[0197] The base station device 30 notifies the terminal device 40 of downlink control information (step S310). This control information may include information related to communication according to the embodiment of this disclosure, such as DCI (Downlink Control Information).

[0198] The terminal device 40 transmits uplink data to the base station device 30 (step S311). The uplink data may include terminal information (information data such as terminal information and sensing information).

[0199] Figure 16 is a sequence diagram showing another example of the notification process flow of terminal information according to the embodiment of this disclosure. The notification process shown in Figure 16 is performed between the terminal device 40 and the base station device 30 within non-terrestrial communication coverage. The process up to the generation of terminal information in step S308 is the same as in Figure 15.

[0200] When terminal information is generated, the terminal device 40 transmits uplink data to the base station device 30 based on the information notified in Configured grant (step S401). The uplink data may include terminal information (information data such as terminal information and sensing information).

[0201] Thus, when the terminal device 40 is communicating (satellite communication) with the base station device 30, if terminal information is generated, it notifies the base station device 30 of the terminal information.

[0202] The terminal device 40 may notify the base station device 30 of terminal information in response to instructions from the base station device 30, or it may notify the base station device 30 of terminal information periodically.

[0203] (Handover process) Figure 17 is a sequence diagram showing an example of the flow of a handover process according to an embodiment of this disclosure. The handover process shown in Figure 17 includes the first handover (movement from within non-terrestrial communication coverage to outside coverage) and the second handover (movement from outside non-terrestrial communication coverage to within coverage) as described above.

[0204] The Source base station equipment shown in Figure 17 is a base station equipment 301 (see Figure 14) that communicates with the terminal equipment 40 via satellite before moving from within the non-terrestrial communication coverage area to outside the coverage area.

[0205] The ground base station equipment shown in Figure 17 is a ground base station equipment 60 (see Figure 14) that performs ground communication with the terminal equipment 40 after moving from within the non-terrestrial communication coverage area to outside the coverage area.

[0206] The Target base station equipment shown in Figure 17 is a base station equipment 302 (see Figure 14) that communicates with the terminal equipment 40 via satellite after moving from outside the non-terrestrial communication coverage into the coverage area.

[0207] Furthermore, it is assumed that, prior to the execution of the handover process shown in Figure 17, a notification process, for example, as shown in Figure 15 or Figure 16, is performed between the Source base station device and the terminal device 40. That is, the Source base station device is assumed to have acquired terminal information regarding the terminal device 40.

[0208] As shown in Figure 17, the Source base station device measures the timing when the device falls outside of non-terrestrial communication coverage based on terminal information (step S501).

[0209] The Source base station device notifies the terminal device 40 of quasi-static control information and also notifies it of non-satellite communication information (step S502).

[0210] Furthermore, the Source base station device requests a handover from the Target base station device (step S503).

[0211] When the Target base station device receives a handover request, it performs admission control (step S504) and notifies the Source base station device of the acknowledgment for the handover request (step S505).

[0212] Furthermore, the terminal device 40, upon receiving non-satellite communication information, begins measuring the timing for transitioning outside of the non-terrestrial communication coverage (step S506). For example, the terminal device 40 begins measuring the timing for performing a first handover based on the first trigger information contained in the non-satellite communication information.

[0213] Here, let's assume that the measurement results indicate that the terminal device 40 has detected a trigger for transitioning outside of non-terrestrial communication coverage (step S507). In this case, the terminal device 40 starts communication outside of non-terrestrial communication coverage (terrestrial communication). For example, the terminal device 40 performs a first handover.

[0214] When terrestrial communication begins, the terminal device 40 starts measuring the timing of the transition to non-terrestrial communication coverage (step S508).

[0215] Subsequently, the terminal device 40 performs ground communication with the ground base station device 60 (step S509).

[0216] Now, let's assume that terminal device 40 has detected a trigger for transitioning to non-terrestrial communication coverage (step S510). In this case, terminal device 40 starts communication within non-terrestrial communication coverage (satellite communication). For example, terminal device 40 performs a second handover.

[0217] The terminal device 40 transmits a Random Access Preamble to the Target base station device (step S511). The terminal device 40 transmits, for example, a collision-free Random Access Preamble to the Target base station device.

[0218] The Target base station device sends a Random Access Response to the terminal device 40 (step S512). The terminal device 40 sends an RRC Reconfiguration Complete to the Target base station device (step S513).

[0219] From this point onward, the terminal device 40 performs satellite communication with the Target base station device.

[0220] As described above, when the terminal device 40 moves from within the non-terrestrial communication coverage area to outside the coverage area, it communicates with the terrestrial base station device 60. Also, when the terminal device 40 moves from outside the non-terrestrial communication coverage area to within the coverage area, it communicates with the Target base station device.

[0221] At this time, the terminal device 40 uses non-satellite communication information obtained from the Source base station device to perform ground communication with the ground base station device 60, including, for example, a first handover. The terminal device 40 also uses satellite communication information obtained from the Source base station device and / or the ground base station device 60 to perform non-ground communication with the Target base station device, including, for example, a second handover.

[0222] As a result, the terminal device 40 can ensure reliable communication even when moving from within the non-terrestrial communication coverage area to outside the coverage area, or from outside the non-terrestrial communication coverage area to within the coverage area.

[0223] <4.1.2. When communication is continued via sidelink communication> In the example described above, it was assumed that the terminal device 40 performs terrestrial communication with the ground base station device 60 as non-satellite communication outside of non-terrestrial communication coverage. However, the non-satellite communication performed by the terminal device 40 is not limited to terrestrial communication. For example, the terminal device 40 may perform sidelink communication with another terminal device 40 as non-satellite communication.

[0224] For example, an area outside of non-terrestrial communication coverage may also be outside the coverage of the terrestrial base station equipment 60 (outside terrestrial communication coverage). In such cases, when terrestrial communication is not possible outside of non-terrestrial communication coverage, terminal equipment 40 can continue communication outside of non-terrestrial communication coverage by performing side-link communication with other terminal equipment 40.

[0225] Figure 18 illustrates another example of communication by the communication system 1 according to the embodiment of this disclosure. In Figure 18, terminal device 401 performs sidelink communication with another terminal device 402 outside the coverage C3 of base station device 30.

[0226] As shown in Figure 18, when the terminal device 401 is located within the coverage C31 of the base station device 301, it communicates with the base station device 30 via satellite. At this time, the base station device 301 can collect terminal information from the terminal device 40. The base station device 301 uses this terminal information to determine, for example, when the terminal device 40 moves outside the coverage C31 of the base station device 301.

[0227] When terminal device 40 moves from within coverage C31 of base station device 301 to area 90 outside coverage C31, terminal device 401 performs sidelink communication (e.g., V2V communication) with another terminal device 402. Sidelink communication between terminal device 40 and ground base station device 60 is non-satellite communication. In this way, terminal device 40 can ensure reliable communication by performing sidelink communication outside coverage C31 of base station device 301.

[0228] The sidelink communication between terminal device 401 and other terminal devices 402 is a network-unassisted inter-device communication. In this way, terminal device 401 transitions from network-assisted communication (satellite communication) to network-unassisted communication by moving from within to outside the non-terrestrial communication coverage.

[0229] At this time, the base station device 301 may notify the terminal device 401 of the transition to network-non-assisted device-to-device communication and the information required for network-non-assisted device-to-device communication (an example of non-satellite communication information).

[0230] When terminal device 401 receives non-satellite communication information from base station device 301, it performs a transition to network-unassisted communication and inter-device communication based on the notified non-satellite communication information.

[0231] Furthermore, when transitioning to network-unassisted device-to-device communication, the base station device 301 may alert the terminal device 401 to the transition to network-unassisted device-to-device communication. Upon receiving the alert, the terminal device 401 may issue an alert to the user (controller) using the terminal device 401, such as a driver, indicating that it is transitioning to network-unassisted communication.

[0232] This allows the user to know when they are transitioning to network-unassisted communication.

[0233] Furthermore, when terminal device 401 moves from outside the coverage C31 of base station device 301 to inside the coverage C32 of base station device 302, it engages in satellite communication with base station device 302. At this time, it is desirable for terminal device 401 to quickly transition to satellite communication with base station device 302.

[0234] This is because, outside of the non-terrestrial communication coverage, network-unassisted communication occurs with other terminal devices 402. Terminal device 401 can perform network-assisted communication by switching to satellite communication with base station device 302, thereby ensuring more reliable communication.

[0235] Furthermore, when transitioning to network-assisted communication, the base station device 302 may alert the terminal device 401 to the transition to network-assisted communication. Upon receiving the alert, the terminal device 401 will issue an alert to the user (controller) using the terminal device 401, such as a driver, indicating that it is transitioning to network-assisted communication.

[0236] This allows the user to know when the system is transitioning to network-assisted communication.

[0237] [Signaling example] An example of signaling that occurs when terminal device 40 communicates with other terminal devices 40 via sidelink communication as non-satellite communication, and communicates with base station device 30 and / or ground base station device 60, will be described below.

[0238] The terminal information that the terminal device 40 notifies the base station device 30 may include the same information as the terminal information when the terminal device 40 performs terrestrial communication as non-satellite communication.

[0239] The non-satellite communication information that the base station device 30 notifies the terminal device 40 may include not only the non-satellite communication information when the terminal device 40 performs terrestrial communication as non-satellite communication, but also sidelink information relating to sidelink communication. The sidelink information may include at least one of the following pieces of information. However, the following information is just an example, and other information that may be necessary for sidelink communication, such as information about existing sidelinks, may also be included as sidelink information. • Information regarding the communication resource pool • Information regarding means of selecting communication resources • Information about resources such as subcarrier spacing and slot length. • Information regarding the number of repeated transmissions • Information regarding modulation schemes • Information regarding error correction codes • Information regarding the Redundancy Version • Information regarding resending • Information about reservation resources • Information regarding measurement • Information regarding the bandwidth used for sidelink communication. • Information regarding the reference signal transmitted via sidelink communication • Information regarding TDD configuration • Information regarding synchronization signals used in sidelink communications • Information regarding transmission power • Information regarding transmission timing

[0240] Thus, when the terminal device 40 performs terrestrial communication as non-satellite communication, the base station device 30 may notify the terminal device 40 of the first HO information and the first trigger information as non-satellite communication information. Alternatively, when the terminal device 40 performs terrestrial communication as non-satellite communication, the base station device 30 may notify the terminal device 40 of sidelink information related to sidelink communication as non-satellite communication information.

[0241] Furthermore, the satellite communication information that the base station device 30 notifies the terminal device 40 may include the same information as the satellite communication information when the terminal device 40 performs terrestrial communication as a non-satellite communication. Also, the second terminal information that the terminal device 40 notifies the base station device 30 may include the same information as the second terminal information when the terminal device 40 performs terrestrial communication as a non-satellite communication.

[0242] [Example of communication processing] When terminal device 401 performs sidelink communication with other terminal device 402 as non-satellite communication, the notification processing performed by communication system 1 may be carried out in the same manner as the notification processing shown in Figures 15 and 16. Furthermore, the handover processing may be carried out in the same manner as the handover processing shown in Figure 17, except that the ground communication performed with the ground base station device 60 in step S509 is replaced by sidelink communication with the other terminal device 402.

[0243] As described above, when terminal device 401 moves from within non-terrestrial communication coverage to outside coverage, it performs side-link communication with other terminal devices 402. Also, when terminal device 401 moves from outside non-terrestrial communication coverage to within coverage, it performs non-terrestrial communication with the Target base station device.

[0244] At this time, terminal device 401 uses non-satellite communication information obtained from Source base station device to perform sidelink communication with other terminal devices 402, for example, including a first handover. Also, terminal device 401 uses satellite communication information obtained from Source base station device to perform non-terrestrial communication with Target base station device, for example, including a second handover.

[0245] As a result, even when the terminal device 401 moves from within the non-terrestrial communication coverage to outside the coverage or from outside the non-terrestrial communication coverage to within the coverage, highly reliable communication can be ensured. Also, even if the outside of the non-terrestrial communication coverage is outside the terrestrial communication coverage, the terminal device 401 can continue communication and ensure highly reliable communication.

[0246] <4.2. Second case> <4.2.1. Case of continuing communication by terrestrial communication> In the first case described above, it was assumed that the base station device 301 that had performed non-terrestrial communication before moving from within the non-terrestrial communication coverage to outside the coverage and the base station device 302 that performs non-terrestrial communication after moving from outside the non-terrestrial communication coverage to within the coverage are different devices. However, the base station device 30 that had performed non-terrestrial communication before moving from within the non-terrestrial communication coverage to outside the coverage and the base station device 30 that performs non-terrestrial communication after moving from outside the non-terrestrial communication coverage to within the coverage may be the same device.

[0247] FIG. 19 is a diagram for explaining an example of a second case of the communication system 1 according to an embodiment of the present disclosure.

[0248] In the example shown in FIG. 19, the base station device 30 forms a coverage C3. The base station device 30 communicates (satellite communication or non-terrestrial network communication) with the terminal device 40 within the coverage C3.

[0249] Here, as shown in FIG. 19, when an obstacle 80 (clouds in the example of FIG. 19) exists, a region 90 outside the coverage of the base station device 30 appears. In the region 90, the terminal device 40 cannot perform satellite communication with the base station device 30.

[0250] In this case, when the terminal device 40 moves from within the coverage C3 of the base station device 30 to outside the coverage C3, for example, it continues communication by performing terrestrial communication with the terrestrial base station device 60.

[0251] Also, when the terminal device 40 moves from outside the coverage C3 of the base station device 30 into the coverage C3, for example, it continues communication by performing non-terrestrial communication with the base station device 30 again.

[0252] Thereby, the terminal device 40 can ensure more reliable communication.

[0253] [Signaling Example] In the second case, the base station device 30 and the terminal device 40 may exchange the following signaling information in addition to / replace the signaling information exchanged in the first case.

[0254] The base station device 30 may notify the terminal device 40 of the following non-satellite communication information in addition to / replace the non-satellite communication information notified to the terminal device 40 in the first case.

[0255] For example, the base station device 30 may notify the terminal device 40 in advance of information until it returns to the non-terrestrial communication coverage as non-satellite communication information. The terminal device 40 may perform operations until it returns to the non-terrestrial communication coverage based on the information. Also, for example, the base station device 30 may notify the terminal device 40 of the satellite communication information described in the first case included in the non-satellite communication information.

[0256] Further, the base station device 30 may notify the terminal device 40 of position information and time information outside the non-terrestrial communication coverage. The terminal device 40 may estimate from this information which positions from which to which the outside of the non-terrestrial communication coverage is, or for how long it will be outside the non-terrestrial communication coverage.

[0257] For example, the non-satellite communication information notified from the base station device 30 to the terminal device 40 includes at least one of the following information. The non-satellite communication information is, for example, information regarding the implementation of a temporary movement outside the non-terrestrial communication coverage. · Information on immediate movement · Timer information until the movement is implemented • Information regarding received power (RSRP information, RSRQ information, RSSI information, etc.)

[0258] For example, satellite communication information notified from base station equipment 30 to terminal equipment 40 includes at least one of the following pieces of information: the satellite communication information is, for example, information regarding a trigger for moving into non-terrestrial communication coverage. • Information regarding received power (RSRP information, RSRQ information, RSSI information, etc.) • Timer information • Information regarding time • Information regarding the start time of the trigger detection operation. • Information regarding what happens after the timer expires. • Information about the surrounding environment

[0259] Furthermore, information about the surrounding environment may include, for example, map information, tunnel brightness information, weather information, and rain cloud information.

[0260] [Example of communication processing] The following describes an example of communication processing in the second case where communication system 1 continues communication by performing terrestrial communication outside of non-terrestrial communication coverage. Note that the notification processing is the same as in the first case (see Figures 15 and 16).

[0261] (Movement process) Figure 20 is a sequence diagram showing an example of the flow of a movement process according to an embodiment of this disclosure. The movement process shown in Figure 20 includes movement from within the non-terrestrial communication coverage to outside the coverage, and movement from outside the non-terrestrial communication coverage to within the coverage. Note that among the processes shown in Figure 20, those processes that are the same as the handover process shown in Figure 17 are denoted by the same reference numerals and their descriptions are omitted.

[0262] Upon detecting the trigger for transitioning to non-terrestrial communication coverage in step S510, the terminal device 40 initiates communication (satellite communication) within the non-terrestrial communication coverage.

[0263] The terminal device 40 transmits a Random Access Preamble to the base station device 30 (step S601). The terminal device 40 transmits, for example, a non-collision-based Random Access Preamble to the base station device 30. The terminal device 40 transmits the Random Access Preamble to the base station device 30 with which it was communicating before moving from within the non-terrestrial communication coverage to outside the coverage.

[0264] The base station device 30 transmits a Random Access Response to the terminal device 40 (step S602). The terminal device 40 transmits an RRC Reconfiguration Complete to the base station device 30 (step S603).

[0265] Thereafter, the terminal device 40 resumes satellite communication with the base station device 30.

[0266] As described above, when the terminal device 40 moves from within the non-terrestrial communication coverage to outside the coverage, it performs terrestrial communication with the terrestrial base station device 60. Also, when the terminal device 40 moves from outside the non-terrestrial communication coverage to within the coverage, it resumes non-terrestrial communication with the base station device 30.

[0267] At this time, the terminal device 40 uses the non-satellite communication information acquired from the base station device 30 to perform terrestrial communication with the terrestrial base station device 60, for example, including a first handover. Also, the terminal device 40 uses the satellite communication information acquired from the base station device 30 and / or the terrestrial base station device 60 to perform non-terrestrial communication with the base station device 30, for example, including a second handover.

[0268] Thereby, the terminal device 40 can ensure highly reliable communication even when moving from within the non-terrestrial communication coverage to outside the coverage or from outside the non-terrestrial communication coverage to within the coverage.

[0269] <When continuing communication by sidelink communication> In the second case, as in the first case described above, the terminal device 40 may perform sidelink communication instead of terrestrial communication outside of non-terrestrial communication coverage.

[0270] Figure 21 is a diagram illustrating another example of a second case of the communication system 1 according to the embodiment of this disclosure.

[0271] In the example shown in Figure 21, there is an area 90 that falls outside the coverage area. In area 90, the terminal device 401 cannot communicate with the base station device 30 via satellite. Also, in the example in Figure 21, area 90 is outside the coverage area (terrestrial communication coverage) of the ground base station device 60. Therefore, in area 90, the terminal device 401 cannot communicate with the ground base station device 60 via terrestrial communication.

[0272] In this case, when terminal device 401 moves from within coverage C3 of base station device 30 to outside coverage C3, it continues communication, for example, by performing sidelink communication with another terminal device 402.

[0273] Furthermore, when the terminal device 401 moves from outside the coverage C3 of the base station device 30 to inside the coverage C3, it continues communication, for example, by resuming non-terrestrial communication with the base station device 30.

[0274] This allows the terminal device 401 to ensure more reliable communication.

[0275] [Signaling example] In the second case, when communication is continued via sidelink communication, the base station equipment 30 and the terminal equipment 40 can exchange signaling information in the same way as in the first case and when communication is continued via terrestrial communication in the second case.

[0276] [Example of communication processing] The following describes an example of communication processing in the second case where communication system 1 continues communication by performing sidelink communication outside of the non-terrestrial communication coverage. The notification processing is the same as in the first case (see Figures 15 and 16).

[0277] (Movement process) Figure 22 is a sequence diagram showing an example of the flow of a movement process according to an embodiment of this disclosure. The movement process shown in Figure 22 includes movement from within the non-terrestrial communication coverage to outside the coverage, and movement from outside the non-terrestrial communication coverage to within the coverage. Note that among the processes shown in Figure 20, those processes that are the same as the handover process shown in Figure 17 are denoted by the same reference numerals and their descriptions are omitted.

[0278] Having detected the trigger for transitioning outside the non-terrestrial communication coverage in step S507, terminal device 401 begins measuring the timing for transitioning back into the non-terrestrial communication coverage (step S508). Terminal device 401 also begins sidelink communication with another terminal device 402 outside the non-terrestrial communication coverage (step S701).

[0279] Upon detecting the trigger for transitioning to non-terrestrial communication coverage in step S510, terminal device 401 initiates communication within non-terrestrial communication coverage (satellite communication).

[0280] For example, the base station device 30 performs a terminal connection check (step S702). The base station device 30 sends, for example, RRC Reconfiguration to the terminal device 401. The base station device 30 responds to the terminal connection (step S703). The terminal device 401 sends, for example, RRC Reconfiguration Complete to the base station device 30.

[0281] From this point onward, terminal device 401 resumes satellite communication with base station device 30.

[0282] As described above, when terminal device 401 moves from within the non-terrestrial communication coverage area to outside the coverage area, it engages in side-link communication with other terminal devices 402. Also, when terminal device 401 moves from outside the non-terrestrial communication coverage area to within the coverage area, it resumes non-terrestrial communication with base station device 30.

[0283] At this time, terminal device 401 uses non-satellite communication information obtained from base station device 30 to perform sidelink communication with other terminal devices 402, for example, including a first handover. Also, terminal device 401 uses satellite communication information obtained from base station device 30 to perform non-terrestrial communication with base station device 30, for example, including a second handover.

[0284] As a result, the terminal device 401 can ensure reliable communication even when moving from within the non-terrestrial communication coverage area to outside the coverage area, or from outside the non-terrestrial communication coverage area to within the coverage area.

[0285] <<5. Other Embodiments>> A Minimization of Driving Test (MDT) can be performed using the communication system 1 described above.

[0286] For example, in wireless communication networks, network optimization is performed by collecting network-related data by mounting terminal devices 40 or test equipment on mobile devices such as cars. This optimization is also called a drive test.

[0287] Because these drive tests are time-consuming and costly, network operators want to reduce the burden of drive testing. Therefore, the objective of MDT is to reduce or eliminate drive tests by collecting the necessary data (measurements) from terminal devices 40.

[0288] A communication system 1 according to the embodiment of this disclosure can be applied in MDT. For example, terminal device 40 notifies base station device 30 of the above-mentioned terminal information (e.g., information related to mobility such as the location information of the terminal device, the speed information of the terminal device, and the direction of movement, sensing information of the terminal device, and information related to the terminal status of the terminal device). Base station device 30 can optimize the network by utilizing the notified information.

[0289] In this case, the terminal device 40 may notify the base station device 30 of whether or not it possesses the capability to collect information collected by MDT and whether or not it can provide the information, including this information in the terminal's Capability information (terminal Capability).

[0290] The base station device 30 may perform network optimization and communication control based on the information notified by the terminal device 40.

[0291] <<6. Variation>> The above-described embodiment is merely an example, and various modifications and applications are possible.

[0292] For example, in the above-described embodiment, the terminal device 40 communicates with the ground station 20 via the satellite station 30, but the terminal device 40 may also communicate with the ground station 20 via an aircraft station. In this case, the satellite station 30 appearing in the above-described embodiment may be read as an aircraft station. Furthermore, the satellite station 30 appearing in the above-described embodiment can be read as a non-ground station (non-ground base station).

[0293] Furthermore, the terminal device 40 may communicate with the ground station 20 via a ground station (ground base station). In this case, the satellite station 30 appearing in the above embodiment may be read as a ground station. The ground station may include a terminal device. In addition, the satellite station 30 appearing in the above embodiment can be read as a base station, a terminal device, or a relay station.

[0294] The control device that controls the management device 10, ground station 20, satellite station 30, and terminal device 40 in this embodiment may be implemented by a dedicated computer system or by a general-purpose computer system.

[0295] For example, a communication program for performing the above-described operations is stored in a computer-readable recording medium such as an optical disc, semiconductor memory, magnetic tape, or flexible disk and distributed. Then, for example, the control device is configured by installing the program on a computer and executing the above-described process. In this case, the control device may be an external device (e.g., a personal computer) of the management device 10, ground station 20, satellite station 30, or terminal device 40. Alternatively, the control device may be an internal device (e.g., control unit 13, control unit 23, control unit 33, or control unit 43) of the management device 10, ground station 20, satellite station 30, or terminal device 40.

[0296] Alternatively, the above communication program may be stored on a disk device provided by a server on a network such as the Internet, and made available for download to a computer. Furthermore, the above functions may be realized through the cooperation of an OS (Operating System) and application software. In this case, the parts other than the OS may be stored on a medium and distributed, or the parts other than the OS may be stored on a server device and made available for download to a computer.

[0297] Furthermore, among the processes described in the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically by known methods. In addition, the processing procedures, specific names, and information including various data and parameters shown in the above document and drawings can be arbitrarily changed unless otherwise specified. For example, the various information shown in each figure is not limited to the information shown.

[0298] Furthermore, the components of each illustrated device are functionally conceptual and do not necessarily need to be physically configured as shown. In other words, the specific forms of distribution and integration of each device are not limited to those shown, and all or part of them can be functionally or physically distributed and integrated in any unit according to various loads and usage conditions.

[0299] Furthermore, the above-described embodiments can be combined as appropriate in areas where the processing content is not contradictory. Also, the order of each step shown in the flowchart of the above-described embodiments can be changed as appropriate.

[0300] Furthermore, for example, this embodiment can also be implemented as any configuration that makes up a device or system, such as a processor as a system LSI (Large Scale Integration), a module using multiple processors, a unit using multiple modules, or a set with additional functions added to a unit (i.e., a configuration of a part of a device).

[0301] In this embodiment, a system refers to a collection of multiple components (devices, modules (parts), etc.), regardless of whether all components are located in the same enclosure. Therefore, multiple devices housed in separate enclosures and connected via a network, and a single device containing multiple modules within a single enclosure, are both considered systems.

[0302] Furthermore, for example, this embodiment can adopt a cloud computing configuration in which a single function is shared and processed collaboratively by multiple devices via a network.

[0303] <<7. Conclusion>>

[0304] Although the embodiments of this disclosure have been described above, the technical scope of this disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the gist of this disclosure. Furthermore, components from different embodiments and modifications may be combined as appropriate.

[0305] Furthermore, the effects described in each embodiment of this specification are merely illustrative and not limiting, and other effects may also occur.

[0306] Furthermore, this technology can also be configured as follows. (1) A terminal device that performs satellite communication with a non-terrestrial base station device, Non-satellite communication information for performing non-satellite communication outside the coverage area of ​​the non-terrestrial base station is obtained from the non-terrestrial base station. A control unit that, when the non-terrestrial base station device moves from within its coverage area to outside its coverage area, performs non-satellite communication using the non-satellite communication information, A terminal device equipped with the following features. (2) The terminal device according to (1), wherein the control unit, when it moves outside the coverage of the non-terrestrial base station device, uses the non-satellite communication information to communicate with the terrestrial base station device. (3) The terminal device according to (2), wherein the non-satellite communication information includes at least one of the following: information regarding handover to the ground base station device, information regarding detachment from the non-ground base station device, and information regarding subsequent handover destinations. (4) The terminal device according to any one of (1) to (3), wherein the control unit, when it moves outside the coverage of the non-terrestrial base station device, uses the non-satellite communication information to perform side-link communication with another terminal device as non-satellite communication. (5) The terminal device described in (4), wherein the non-satellite communication information includes information relating to side-link communication. (6) The terminal device according to any one of (1) to (5), wherein the non-satellite communication information includes information regarding the trigger for movement outside the coverage of the non-terrestrial base station device. (7) The terminal device according to (6), wherein the information relating to the trigger for the non-terrestrial base station device to move outside the coverage includes at least one of: threshold information relating to the received power of the non-terrestrial base station device within the coverage; information relating to a timer that performs the movement of the non-terrestrial base station device from within the coverage to outside the coverage; information relating to the time at which the movement of the non-terrestrial base station device from within the coverage to outside the coverage is performed; and information relating to the execution of the movement of the non-terrestrial base station device from within the coverage to outside the coverage. (8) The aforementioned non-terrestrial base station equipment is a first non-terrestrial base station equipment, The terminal device according to any one of (1) to (7), wherein the control unit moves from outside the coverage of the first non-terrestrial base station device into the coverage of the first non-terrestrial base station device to perform satellite communication with the second non-terrestrial base station device. (9) The terminal device according to (8), wherein the control unit acquires satellite communication information to be used for satellite communication when the device moves from outside the coverage of the first non-terrestrial base station device into the coverage of the second non-terrestrial base station device. (10) The terminal device according to (9), wherein the control unit acquires the satellite communication information from the first non-terrestrial base station device. (11) The terminal device according to (9) or (10), wherein the control unit acquires the satellite communication information from a ground base station device that performs the non-satellite communication outside the coverage of the first non-terrestrial base station device. (12) The second non-terrestrial base station device is the terminal device described in any one of (8) to (11), which is the first non-terrestrial base station device. (13) The non-satellite communication information includes information regarding the trigger for the first non-terrestrial base station equipment to move outside the coverage area, The terminal device according to (12), wherein the information relating to the trigger for the movement outside the coverage of the first non-terrestrial base station device includes at least one of information regarding immediate movement, timer information until the movement is performed, and information regarding received power. (14) The satellite communication information used in the satellite communication when the first non-terrestrial base station device moves from outside the coverage of the first non-terrestrial base station device into the coverage of the second non-terrestrial base station device includes information regarding the trigger for moving into the coverage of the second non-terrestrial base station device. The terminal device according to (12) or (13), wherein the information relating to the movement trigger into the coverage of the second non-terrestrial base station device includes at least one of the following: information relating to received power, timer information, time information, information relating to the start time of the trigger detection operation, information relating to the operation after the timer has finished, and information relating to the surrounding environment. (15) The second non-terrestrial base station device is a terminal device described in any one of (8) to (11), which is different from the first non-terrestrial base station device. (16) The terminal device according to (15), wherein the second non-terrestrial base station device acquires inter-satellite information for use in satellite communications when it moves within the coverage of the second non-terrestrial base station device from the first non-terrestrial base station device. (17) The control unit notifies the non-terrestrial base station device of the terminal information, The non-terrestrial base station device uses the terminal information to estimate the timing at which the terminal device falls outside the coverage area of ​​the non-terrestrial base station device. A terminal device as described in any one of (1) to (16). (18) A base station device that performs satellite communication with terminal devices, A control unit that notifies the terminal device of non-satellite communication information for the terminal device to perform non-satellite communication outside the coverage area of ​​the base station device, Equipped with, When the terminal device moves from within the coverage area of ​​the base station device to outside the coverage area, it performs non-satellite communication using the non-satellite communication information. Base station equipment. (19) A communication method in which a terminal device communicates with a non-terrestrial base station device via satellite, To obtain non-satellite communication information from the non-terrestrial base station equipment for performing non-satellite communication outside the coverage area of ​​the non-terrestrial base station equipment, When the non-terrestrial base station device moves from within its coverage area to outside its coverage area, it performs non-satellite communication using the non-satellite communication information. A communication method that includes this. (20) A communication method in which a base station device communicates with a terminal device via satellite, To notify the terminal device of non-satellite communication information for the terminal device to perform non-satellite communication outside the coverage area of ​​the base station device, Includes, When the terminal device moves from within the coverage area of ​​the base station device to outside the coverage area, it performs non-satellite communication using the non-satellite communication information. Communication method. [Explanation of symbols]

[0307] 1. Communication System 10 Management device 20 Ground stations 30, 50 satellite stations 40 Terminal devices 60 Ground base station equipment 70 Aircraft Bureau 11 Communications Department 21, 31, 41 Wireless Communication Section 12, 22, 32, 42 storage section 13, 23, 33, 43 Control Unit

Claims

1. A terminal device that performs satellite communication with a first non-terrestrial base station device, Non-satellite communication information for performing non-satellite communication outside the coverage area of ​​the first non-terrestrial base station is obtained from the first non-terrestrial base station, When the first non-terrestrial base station device moves from within its coverage area to outside its coverage area, it performs non-satellite communication with a ground device using the non-satellite communication information. When the first non-terrestrial base station device moves from outside its coverage area to inside the coverage area of ​​the second non-terrestrial base station device, the control unit performs satellite communication with the second non-terrestrial base station device using satellite communication information. Equipped with, The aforementioned satellite communication information is obtained from the first non-terrestrial base station equipment. Terminal device.

2. The terminal device according to claim 1, wherein the control unit, when it moves outside the coverage area of ​​the first non-terrestrial base station device, uses the non-satellite communication information to communicate with the terrestrial base station device.

3. The terminal device according to claim 2, wherein the non-satellite communication information includes at least one of information relating to a handover to the ground base station device, information relating to detachment from the first non-ground base station device, and information relating to the handover destination for satellite communication after the non-satellite communication.

4. The terminal device according to claim 1, wherein the control unit, when it moves outside the coverage of the first non-terrestrial base station device, uses the non-satellite communication information to perform side-link communication with another terminal device as non-satellite communication.

5. The terminal device according to claim 4, wherein the non-satellite communication information includes information relating to side-link communication.

6. The terminal device according to claim 1, wherein the non-satellite communication information includes information regarding a trigger for movement outside the coverage of the first non-terrestrial base station device.

7. The terminal device according to claim 6, wherein the information relating to the trigger for the movement of the first non-terrestrial base station device out of coverage includes at least one of: threshold information relating to the received power of the first non-terrestrial base station device within the coverage; information relating to a timer that performs the movement of the first non-terrestrial base station device from within the coverage to outside the coverage; information relating to the time at which the movement of the first non-terrestrial base station device from within the coverage to outside the coverage is performed; and information relating to the execution of the movement of the first non-terrestrial base station device from within the coverage to outside the coverage.

8. The terminal device according to claim 1, wherein the second non-terrestrial base station device is the first non-terrestrial base station device.

9. The non-satellite communication information includes information regarding the trigger for the first non-terrestrial base station device to move outside the coverage area, The terminal device according to claim 8, wherein the information relating to the trigger for the movement outside the coverage of the first non-terrestrial base station device includes at least one of information regarding immediate movement, timer information until the movement is performed, and information regarding received power.

10. The satellite communication information used in the satellite communication when the first non-terrestrial base station device moves from outside the coverage to inside the coverage of the second non-terrestrial base station device includes information regarding the trigger for moving into the coverage of the second non-terrestrial base station device. The terminal device according to claim 8, wherein the information relating to the movement trigger into the coverage of the second non-terrestrial base station device includes at least one of the following: information relating to received power, timer information, time information, information relating to the start time of the trigger detection operation, information relating to the operation after the timer has finished, and information relating to the surrounding environment.

11. The terminal device according to claim 1, wherein the second non-terrestrial base station device is different from the first non-terrestrial base station device.

12. The terminal device according to claim 11, wherein the second non-terrestrial base station device acquires inter-satellite information for use in satellite communications when it moves within the coverage of the second non-terrestrial base station device from the first non-terrestrial base station device.

13. The control unit notifies the first non-terrestrial base station device of the terminal information, The first non-terrestrial base station device uses the terminal information to estimate the timing at which the terminal device falls outside the coverage of the first non-terrestrial base station device. The terminal device according to claim 1.

14. A base station device that performs satellite communication with terminal devices, A control unit that notifies the terminal device of non-satellite communication information for the terminal device to perform non-satellite communication outside the coverage area of ​​the base station device, Equipped with, The aforementioned terminal device is When the base station device moves from within its coverage area to outside its coverage area, it performs non-satellite communication with the ground device using the non-satellite communication information. When the aforementioned base station device moves from outside the coverage area to within the coverage area of ​​another base station device, it performs satellite communication with the other base station device using satellite communication information. The satellite communication information is acquired from the base station equipment. Base station equipment.

15. A communication method in which a terminal device performs satellite communication with a first non-terrestrial base station device, To obtain non-satellite communication information from the first non-terrestrial base station equipment for performing non-satellite communication outside the coverage area of ​​the first non-terrestrial base station equipment, When the first non-terrestrial base station device moves from within its coverage area to outside its coverage area, it performs non-satellite communication with a ground device using the non-satellite communication information. When the first non-terrestrial base station device moves from outside its coverage area to within its coverage area, it performs satellite communication with the second non-terrestrial base station device using satellite communication information. The satellite communication information is obtained from the first non-terrestrial base station equipment, A communication method that includes this.

16. A communication method in which a base station device communicates with a terminal device via satellite, To notify the terminal device of non-satellite communication information for the terminal device to perform non-satellite communication outside the coverage area of ​​the base station device, Includes, When the terminal device moves from within the coverage area of ​​the base station device to outside the coverage area, it uses the non-satellite communication information to communicate with the ground device. stomach, When the aforementioned base station device moves from outside the coverage area to within the coverage area of ​​another base station device, it performs satellite communication with the other base station device using satellite communication information. The satellite communication information is acquired from the base station equipment. Communication method.

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