Communication device, communication method, and communication system

Abstract

A communication device of the present invention is connected to a first non-stationary satellite station among a plurality of non-stationary satellite stations forming a fixed-position cell on the ground. The communication apparatus includes: an acquisition unit that acquires, from a first non-stationary satellite station, information related to a handover of a connection from the first non-stationary satellite station to a second non-stationary satellite station among the plurality of non-stationary satellite stations prior to a handover process; and a switching processing unit that switches the connection from the first non-stationary satellite station to the second non-stationary satellite station without performing a random access procedure on the basis of the information relating to the switching of the connection.

Description

TECHNICAL FIELD

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

[0002] In recent years, with an increase in demand for communication performance such as wide-area coverage, research has been initiated on non-terrestrial networks (NTNs) in which a radio network is provided from a device floating in the air or in space. In non-terrestrial networks, a non-geostationary non-ground station such as a medium earth orbit satellite, a low earth orbit satellite, and a high altitude platform station (HAPS) can be used as a base station or a relay station.

[0003] LIST OF CITATIONS

[0004] PATENT LITERATURE

[0005] PTL 1: International Publication No. 2021 / 230107

[0006] NON-PATENT LITERATURE

[0007] NPL 1: R2-1916351, Thales, “[108 #06] [NTN] Earth fixed vs. Earth moving cells in NTN LEO (Thales)”, 3GPP TSG RAN2 Meeting #108, Reno, USA, November 18-22, 2019. SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] Unlike a known base station or relay station fixed on the ground, a non-geostationary non-ground station appears to be highly moving in the sky when viewed from a terminal device on the ground. Accordingly, in the case where a known communication technique is directly applied to a non-terrestrial network, it can be impossible to achieve communication with high communication performance (e.g., connection stability, low latency, high reliability, high throughput, power saving, low processing load, and the like).

[0010] Therefore, the present disclosure proposes a communication device, a communication method, and a communication system capable of achieving high communication performance.

[0011] Note that the foregoing described problem or object is only one of a plurality of problems or objects that can be solved or achieved by the plurality of embodiments disclosed in this specification.

[0012] SOLUTION TO THE PROBLEM

[0013] To solve the problems described above, a communication device according to an aspect of the present disclosure is configured to connect to a first non-geostationary satellite station among a plurality of non-geostationary satellite stations that form a position-fixed cell on the ground, wherein the communication device includes an acquisition section configured to acquire, in advance from the first non-geostationary satellite station before a handover process, information related to a handover of a connection from the first non-geostationary satellite station to a second non-geostationary satellite station among the plurality of non-geostationary satellite stations, and a handover process section configured to hand over the connection from the first non-geostationary satellite station to the second non-geostationary satellite station without performing a random access procedure, based on the information related to the handover of the connection. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a diagram for describing an operation of a non-terrestrial network using a geostationary cell.

[0015] Figure 2 is a diagram showing a configuration example of a communication system according to an embodiment of the present disclosure.

[0016] Figure 3 is a diagram showing an example of a radio network provided by the communication system.

[0017] Figure 4 is a diagram showing an overview of satellite communication provided by the communication system.

[0018] Figure 5 is a diagram showing an example of a cell formed by a non-geostationary satellite station.

[0019] Figure 6 is a diagram showing a configuration example of a management device according to an embodiment of the present disclosure.

[0020] Figure 7 is a diagram showing a configuration example of a ground station according to an embodiment of the present disclosure.

[0021] Figure 8 is a diagram showing a configuration example of a non-ground station according to an embodiment of the present disclosure.

[0022] Figure 9 is a diagram showing a configuration example of a relay station according to an embodiment of the present disclosure.

[0023] Figure 10 is a diagram showing a configuration example of a terminal device according to an embodiment of the present disclosure.

[0024] Figure 11 is a flowchart showing an example of an initial connection process.

[0025] Figure 12 is a diagram illustrating a contention-based random access procedure.

[0026] Figure 13 is a diagram illustrating a non-contention-based random access procedure.

[0027] Figure 14 is a diagram illustrating a 2-step random access procedure.

[0028] Figure 15 is a diagram illustrating an example of a handover sequence of a cell formation area.

[0029] Figure 16 is a diagram illustrating another example of a handover sequence of a cell formation area. DETAILED DESCRIPTION

[0030] Embodiments of the present disclosure will be described in detail below based on the accompanying drawings. In the following embodiments, the same components are denoted by the same reference numerals, and repetitive description thereof will be omitted.

[0031] In the present specification and drawings, a plurality of components having substantially the same functional configuration can be distinguished from each other by appending different numerals to the same reference numeral. For example, a plurality of configurations having substantially the same functional configuration are distinguished as terminal devices 501, 502, and 503, as necessary. However, where it is unnecessary to particularly distinguish a plurality of components having substantially the same functional configuration from each other, the components are simply denoted by the same reference numeral. For example, where it is unnecessary to particularly distinguish the terminal devices 501, 502, and 503 from each other, the terminal devices are simply referred to as terminal device 50.

[0032] One or more embodiments (examples and modifications) described below can each be independently implemented. On the other hand, at least some of a plurality of embodiments described below can be appropriately combined with at least some other embodiments. A plurality of embodiments can include novel features different from each other. Therefore, a plurality of embodiments can contribute to solving different purposes or problems, and can exhibit different effects.

[0033] Further, the present disclosure will be described in accordance with the following item order.

[0034] 1. SUMMARY

[0035] 2. CONFIGURATION OF COMMUNICATION SYSTEM

[0036] 2-1. CONFIGURATION EXAMPLE OF MANAGEMENT DEVICE

[0037] 2-2. CONFIGURATION EXAMPLE OF GROUND STATION

[0038] 2-3. CONFIGURATION EXAMPLE OF NON-GROUND STATION

[0039] 2-4. Configuration example of base station

[0040] 2-5. Configuration example of relay station

[0041] 2-6. Configuration example of terminal device

[0042] 3. Basic operation of communication system

[0043] 3-1. Initial connection processing

[0044] 3-2. Random access procedure

[0045] 3-3. Details of random access procedure of NR

[0046] 3-4. 2-step RACH of NR

[0047] 4. Operation of communication system

[0048] 4-1. Overview of processing

[0049] 4-2. Notification of information related to handover of cell-formed area

[0050] 4-3. Handover of cell-formed area

[0051] 4-4. Processing of skipping random access procedure and the like

[0052] 4-5. Continuous transmission of same data

[0053] 4-6. Communication between base stations

[0054] 5. Sequence example

[0055] 5-1. Sequence example 1

[0056] 5-2. Sequence example 2

[0057] 6. Variations

[0058] 7. Conclusion

[0059] 1. Overview

[0060] 3GPP (registered trademark) is studying radio access technologies (RATs) such as long term evolution (LTE) and new radio (NR). LTE and NR are types of cellular communication technologies, and enable mobile communication of terminal devices by allocating a plurality of areas covered by base stations in a cellular manner (e.g., eNode (eNB), gNode (gNB), or RAN node (including EUTRAN and NGRAN)). Research on 6G has begun in recent years. 6G is also a type of cellular communication technology. This technology enables mobile communication of terminal devices by allocating a plurality of areas covered by base stations in a cellular manner. Note that a single base station can manage a plurality of cells.

[0061] Note that in the following description, "LTE" includes LTE-Advanced (LTE-A), LTE-Advanced Pro (LTE-A Pro), and evolved universal terrestrial radio access (EUTRA). NR includes new radio access technology (NRAT) and further EUTRA (FEUTRA). Note that a single base station can manage a plurality of cells. In the following description, a cell corresponding to LTE is referred to as an LTE cell, and a cell corresponding to NR is referred to as an NR cell.

[0062] NR is a next-generation radio access scheme for LTE, and is a radio access technology (RAT) different from LTE. NR is a radio access technology that can support various use cases, including enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low-latency communication (URLLC). NR can implement a technical framework corresponding to use cases, requirements, deployment scenarios, and the like in these use cases.

[0063] 6G is a cellular communication technology belonging to the next generation of NR and 5GS (5G system) corresponding to the fifth generation of mobile communication. 6G includes radio access technologies and network technologies between base stations, core networks, and data networks. 6G will be seen as a high-level of eMBB, mMTC, and URLLC, which are major use cases or requirements in NR. Technologies provided in 6G can include AI-related technologies (e.g., cognitive network, AI-native air interface), sensing-related technologies (e.g., radar sensing, network as a sensor), and terahertz communication-related technologies.

[0064] 1-1. Objectives

[0065] In cellular mobile communication, a radio network is configured by base stations or relay stations (hereinafter also referred to as ground stations) installed on the ground that form cells (e.g., macro cells, micro cells, femto cells, or small cells). The base stations / relay stations installed on the ground are referred to as ground stations (or ground base stations / ground relay stations). The radio network provided by the ground stations is referred to as a terrestrial network.

[0066] On the other hand, with a decrease in cost for base stations and an increase in demand for providing coverage to areas where radio waves from base stations are difficult to reach, and the like, research is being conducted on providing radio networks for terminal devices by base stations / relay stations other than ground stations, such as satellite stations or aircraft stations. Base stations / relay stations other than ground stations are referred to as non-ground stations (or non-ground base stations / non-ground relay stations). Radio networks provided from non-ground stations are referred to as non-terrestrial networks (NTNs). By using the same radio access scheme for terrestrial networks and non-terrestrial networks, it is possible to operate terrestrial networks and non-terrestrial networks in an integrated manner.

[0067] Among non-ground stations, non-geostationary non-ground stations such as medium earth orbit satellite stations and low earth orbit satellite stations move at high speed in the sky as viewed from mobile terminals on the ground. Specifically, low earth orbit satellite stations move in the air at approximately 7.6 km / s. Accordingly, cells formed on the ground by non-ground stations also move at high speed similarly to non-ground stations. In the following description, cells that move on the ground in accordance with the movement of non-ground stations can be referred to as earth-moving cells. Non-terrestrial networks that use earth-moving cells have, for example, a problem of frequent occurrence of handover associated with the movement of cells.

[0068] To solve this problem, it is assumed that a cell forming means for fixing the positions of cells formed on the ground is employed. For example, non-ground stations such as satellite stations fix the positions of cells formed on the ground by steering cell-forming beams, and the like. In the following description, cells whose positions are fixed can be referred to as earth-fixed cells. In the case of implementing non-terrestrial networks that use earth-fixed cells, the positions of cells on the ground are fixed, and thus it is assumed that the problem described above (e.g., frequent occurrence of handover) is solved. Specifically, in future non-terrestrial networks, it is expected that very low earth orbit satellites that operate around very low earth orbits (VLEOs) will be utilized. In the case of using earth-moving cells in non-terrestrial networks that use very low earth orbit satellites, the handover period is very short (e.g., approximately 3.7 seconds in the case of a short period). Accordingly, it is assumed that earth-fixed satellites will be utilized for future non-terrestrial networks.

[0069] Figure 1 is a diagram for describing the operation of non-terrestrial networks that use earth-fixed cells. In the example of Figure 1 In the example of, earth-fixed cells (earth-fixed cells) are formed on the ground. In the following description, the positions at which cells are formed are referred to as cell positions or simply as cells. Each of satellite stations A and B is one of a plurality of non-geostationary satellite stations that form earth-fixed cells (cells 1 to 3) in the example of Figure 1 In the example of, earth-fixed cells (earth-fixed cells) are formed on the ground. In the following description, the positions at which cells are formed are referred to as cell positions or simply as cells. Each of satellite stations A and B is one of a plurality of non-geostationary satellite stations that form earth-fixed cells (cells 1 to 3) in the example of

[0070] The satellite station A and the satellite station B each form a communication area (hereinafter also referred to as a cell formation area) at a predetermined cell position on the ground. In Figure 1 the example, the satellite station A forms a communication area (cell formation area A) at the position of cell 2 at time T. Figure 1 The satellite station B forms a communication area (cell formation area B) at the position of cell 3 at time T. The terminal device is located at the position of cell 2. Accordingly, the terminal device belongs to the communication area (cell formation area A) formed by the satellite station A at time T. Figure 1

[0071] The satellite station A and the satellite station B control beams and the like, so that the communication areas (cell formation areas) formed on the ground are kept in a state of being fixed to the predetermined cell positions even when the positions of the satellite stations change due to movement. For example, at time T+t1, the satellite station A steers a beam so as to fix the communication area (cell formation area A) formed by the satellite station A to the position of cell 2. At time T+t1, the satellite station B steers a beam so as to fix the communication area (cell formation area B) formed by the satellite station B to the position of cell 3.

[0072] As time further advances, it becomes difficult for the satellite station A and the satellite station B to keep the communication areas (cell formation areas) at the current cell positions. At this time, the satellite station A and the satellite station B move the communication areas to the next cell positions. For example, at time T+t1+t2, the satellite station A forms a communication area (cell formation area A) at the position of cell 1. At time T+t1+t2, the satellite station B forms a communication area (cell formation area B) at the position of cell 2. At this time, the terminal device switches a connection from the communication area (cell formation area A) formed by the satellite station A to the communication area (cell formation area B) formed by the satellite station B. At this time, the satellite station A and the satellite station B share information related to cell formation between the satellite station A and the satellite station B, and move the cell formation areas. Accordingly, the terminal device can switch the satellite station in a manner in which no cell handover occurs (transparently).

[0073] However, in the case where the known communication technology is directly applied to the non-terrestrial network using the earth-fixed cell, there is a possibility that communication having high communication performance (e.g., connection stability, low delay, high reliability, high throughput, power saving, low processing load, and the like) cannot be achieved. For example, even in the case where information can be shared between the satellite stations so as to appear that no cell handover occurs, in reality, the terminal device can not be able to smoothly switch the satellite station.

[0074] As a specific example, in addition to the handover, it is assumed that the non-terrestrial network using the earth-fixed cell has problems as described in (1) to (3) below, for example.​

[0075] (1) Switching is performed instantaneously between downlink beam direction and uplink beam direction. Accordingly, the terminal device needs to switch the beam direction to the appropriate direction at the timing at which the satellite station is switched.

[0076] (2) Switching of the satellite station to be connected instantaneously causes a difference in propagation delay. Accordingly, the communication device (terminal device and / or base station) needs to update information related to downlink-uplink frame synchronization, timing advance compensation, and the like.

[0077] (3) The problems described above occur simultaneously in all terminal devices, and thus a large amount of signaling and the like occurs simultaneously. Accordingly, it is necessary to reduce the signaling overhead.

[0078] Note that the problems described above are merely examples. The problems of the non-terrestrial network using the earth-fixed cell are not limited to those described above.

[0079] 1-2. Summary of solutions

[0080] In the present embodiment, the problems described above are solved by the following means. Note that the description regarding the base station appearing in the following description can be replaced with the description regarding the relay station as appropriate.

[0081] The communication system according to the present embodiment includes a base station and a terminal device. The base station is a non-terrestrial station that connects to the terminal device as a first non-geosynchronous satellite station among a plurality of non-geosynchronous satellite stations that form position-fixed cells on the ground. Alternatively, the base station is a terrestrial station that connects to the terminal device using the first non-geosynchronous satellite station as a relay station.

[0082] Before the terminal device switches the connection from the first non-geosynchronous satellite station to a second non-geosynchronous satellite station, the base station notifies the terminal device in advance of information related to the switching of the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station (for example, a satellite station B shown in FIG. 1). The first non-geosynchronous satellite station and the second non-geosynchronous satellite station are each one of the plurality of non-geosynchronous satellite stations. For example, the first non-geosynchronous satellite station is a satellite station A shown in FIG. 1, and the second non-geosynchronous satellite station is the satellite station B shown in FIG. 1. Figure 1 Figure 1 Figure 1

[0083] ​​​The information related to the handover of the connection can include information related to communication parameters after the handover of the connection. For example, the information related to the communication parameters can include at least one of information related to timing advance, information related to terminal-specific transmission timing synchronization, information related to cell-common transmission timing synchronization, information related to transmission weight, information related to HARQ disable, information related to position, orbit, time, and altitude of the satellite device, or information related to transmission power. Furthermore, the information related to the handover of the connection can include position information of the second non-geosynchronous satellite station (i.e., information related to beam direction after the handover of the connection).

[0084] Before the handover processing from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station, the terminal device acquires in advance, from the first non-geosynchronous satellite station, information related to the handover of the connection. Based on the information related to the handover of the connection, the terminal device switches the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station without handover (i.e., without performing a random access procedure).

[0085] Thus, the terminal device acquires in advance, from the non-geosynchronous satellite station, information related to the handover of the connection before the handover of the connection. Accordingly, even if communication is implemented using a non-terrestrial network and the non-terrestrial network is using earth-fixed cells, the terminal device can smoothly implement the handover of the connection using the information related to the handover of the connection. As a result, the terminal device can implement communication with high communication performance.

[0086] It should be noted that the base station implementing the technology described in the present embodiment is a non-terrestrial base station device operating as a communication device, such as a satellite station, a drone, a balloon, or an airplane. The base station implementing the present technology can be a gateway deployed on the ground (transparent payload scheme). The present technology is also applicable to communication between a terrestrial base station device and a terminal device.

[0087] The foregoing describes an overview of the present embodiment, and a communication system according to the present embodiment will be described in detail below.

[0088] 2. Configuration of the communication system

[0089] First, the configuration of the communication system 1 of the present embodiment will be described.

[0090] The communication system 1 is a cellular communication system using a radio access technology such as LTE, NR, or 6G. The communication system 1 provides radio communication for terminal devices on the ground through non-ground stations (e.g., satellite stations or aircraft stations). In a case where the non-ground stations are satellite stations, the communication system 1 can be a bent-pipe (transparent) type mobile satellite communication system. Of course, some or all of the non-ground stations included in the communication system 1 can be configured to function as base stations rather than relay stations.

[0091] The radio access scheme used by the communication system 1 is typically NR, but is not limited thereto. The radio access scheme used by the communication system 1 can be a radio access scheme other than NR, such as 6G, LTE, Wideband Code Division Multiple Access (W-CDMA), or Code Division Multiple Access 2000 (cdma 2000). Of course, the radio access scheme used by the communication system 1 can be a radio access scheme of a subsequent generation to 6G.

[0092] It should be noted that, in the present embodiment, a ground station (also referred to as a ground base station) refers to a base station (including a relay station) installed on the ground. Here, the “ground” is not only the land but also the ground in a broad sense including the underground, the water surface, and the underwater. It should be noted that, in the following description, the term “ground station” can be replaced with “gateway”.

[0093] The techniques of the present disclosure are not only applicable to communication between non-ground base stations and terminal devices, but also applicable to communication between terrestrial base stations and terminal devices. At this time, the ground base stations and the terminal devices can communicate with each other through non-ground stations such as satellite stations or aircraft stations.

[0094] The configuration of the communication system 1 will be described in detail hereinafter.

[0095] Figure 2 is a diagram illustrating a configuration example of the communication system 1 according to the embodiment of the present disclosure. The communication system 1 includes a management device 10, a ground station 20, a non-ground station 30, a relay device 40, and a terminal device 50. The communication system 1 provides a radio network capable of mobile communication for users through the cooperative operation of the radio communication devices constituting the communication system 1. The radio network of the present embodiment includes, for example, a radio access network and a core network. In the present embodiment, the radio communication devices are devices having a radio communication function, and in the present embodiment, the radio communication devices are classified into the ground station 20, the non-ground station 30, the relay device 40, and the terminal device 50. Figure 2 corresponds to the ground station 20, the non-ground station 30, the relay station 40, and the terminal device 50 in the example of

[0096] The communication system 1 can include a plurality of management devices 10, a plurality of ground stations 20, a plurality of non-ground stations 30, a plurality of relay stations 40, and a plurality of terminal devices 50. In the present embodiment, the ground station 20, the non-ground station 30, the relay device 40, and the terminal device 50 are not limited in number. Figure 2In the example, communication system 1 includes management devices 101, 102, etc., which serve as management devices 10. Communication system 1 also includes ground stations 201, 202, etc., which serve as ground stations 20, and non-ground stations 301, 302, etc., which serve as non-ground stations 30. Communication system 1 also includes relay stations 401, 402, etc., which serve as relay stations 40, and terminal devices 501, 502, 503, etc., which serve as terminal devices 50.

[0097] Figure 3 This is a diagram illustrating an example of a radio network provided by communication system 1.

[0098] Management device 10 is, for example, a device constituting the core network CN. Management device 10 is connected to network PN. Management device 10 is connected to ground station 20 and non-ground station 30, and allows terminal device 50 to connect to network PN. Network PN is a public data network such as the Internet. Network PN is not limited to the Internet, and can be, for example, a local area network (LAN), a wide area network (WAN), a telephone network (mobile phone network, fixed phone network, etc.), or a local Internet Protocol (IP) network. Of course, network PN can be another mobile network. For example, network PN can be a cellular network provided by an entity different from the entity operating communication system 1 (e.g., a commercial entity such as a mobile network operator (MNO)).

[0099] Ground station 20 and non-ground station 30 are base stations or relay stations. In the following description, ground station 20 and non-ground station 30 are base stations, but ground station 20 and non-ground station 30 can be relay stations. Ground station 20 is, for example, a ground base station in a structure installed on the ground, and non-ground station 30 is, for example, a non-ground base station such as a satellite station or a High Altitude Platform Station (HAPS). Ground station 20 and non-ground station 30 each constitute a cell. A cell is an area that covers radio communication. The cell can be any of macrocells, microcells, femtocells, and small cells. It should be noted that the communication system 1 can be configured such that a single base station (satellite station) manages multiple cells, or it can be configured such that multiple base stations manage one cell.

[0100] exist Figure 3 In the example, ground stations 201 and 202 constitute terrestrial network TN1, and ground stations 203, 204, and 205 constitute terrestrial network TN2. Terrestrial networks TN1 and TN2 are networks operated by radio communication companies such as telephone companies. Terrestrial networks TN1 and TN2 may be operated by different radio communication service providers, or they may be operated by the same radio communication service provider. Terrestrial networks TN1 and TN2 can be considered as a single terrestrial network.

[0101] The terrestrial network TN1 and the terrestrial network TN2 are each connected to a core network. In Figure 3 In the example shown in FIG. 1, the ground stations 20 that constitute the terrestrial network TN2 are connected to a core network CN including a management device 101 and the like, for example. In the case where the radio access scheme of the terrestrial network TN2 is LTE, the core network CN is an EPC. In the case where the radio access scheme of the terrestrial network TN2 is NR, the core network CN is a 5GC. Of course, the core network CN is not limited to the EPC or the 5GC, and can be a core network of another radio access scheme. It should be noted that, in the example shown in FIG. 1, the terrestrial network TN1 is not connected to a core network, but the terrestrial network TN1 can be connected to the core network CN. The terrestrial network TN1 can be connected to a core network (not shown) different from the core network CN. Figure 3

[0102] The core network CN includes a gateway device and a gateway switch, for example, and is connected to the network PN through the gateway device or the gateway switch. As described earlier, the network PN is a public network such as the Internet. The gateway device can be a server device connected to the Internet, a regional IP network, or the like. The gateway switch is a switch connected to a telephone network of a telephone company, for example. The management device 101 can have a function as the gateway device or the gateway switch.

[0103] Figure 3 The non-terrestrial stations 30 shown in FIG. 1 are satellite stations or aircraft stations, for example. A group of satellite stations (or satellite stations) that constitute a non-terrestrial network is referred to as a space-based platform. A group of aircraft stations (or aircraft stations) that constitute a non-terrestrial network is referred to as an air-based platform. In Figure 3 In the example shown in FIG. 1, the non-terrestrial stations 301, 302, 303 constitute a space-based platform SBP1, and the non-terrestrial station 304 constitutes a space-based platform SBP2. The non-terrestrial station 305 constitutes an air-based platform ABP1.

[0104] The non-terrestrial stations 30 can be able to communicate with the terrestrial networks or the core network through the relay stations 40. Of course, the non-terrestrial stations 30 can be able to directly communicate with the terrestrial networks or the core network without intervention of the relay stations 40. It should be noted that the non-terrestrial stations 30 can be able to communicate with the terminal devices 50 through the relay stations 40, or can be able to directly communicate with the terminal devices 50. The non-terrestrial stations 30 can be able to directly communicate with each other without intervention of the relay stations 40.

[0105] The relay stations 40 relay communication between devices on the ground and the non-terrestrial stations 30. The relay stations 40 can be ground stations or non-terrestrial stations. In Figure 3 ​In the example of FIG. 4, the relay station 402 relays communications between the ground station 20 and the non-ground station 30, and the relay station 401 relays communications between the management device 10 and the non-ground station 30. It should be noted that the relay station 40 can relay communications between the terminal device 50 and the non-ground station 30. The relay station 40 can also be capable of communicating with another relay station 40.

[0106] The terminal device 50 can communicate with both the ground station and the non-ground station. In the example of FIG. 5, the terminal device 501 can communicate with the ground station 20. The terminal device 501 can communicate with the non-ground station 30. It should be noted that the terminal device 50 can be capable of communicating with the relay station 40. The terminal device 50 can be capable of directly communicating with another terminal device 50. The terminal device 501 can be capable of directly communicating with the terminal device 502. Figure 3

[0107] The devices constituting the space-based platforms SBPl and SBP2 perform satellite communications with the terminal device 50. Satellite communications are radio communications between a satellite station and a terminal device. Figure 4 FIG. 6 is a diagram showing an overview of satellite communications provided by the communication system 1. Satellite stations are generally classified into geostationary satellite stations and low earth orbit satellite stations.

[0108] A geostationary satellite station is a satellite station located in a geostationary orbit, and rotates around the Earth at the same speed as the rotation of the Earth. In the example of FIG. 4, the non-ground station 304 constituting the space-based platform SBP2 is a geostationary satellite station. Among satellite orbits, a geostationary orbit is an orbit at an altitude of approximately 35,786 km. A geostationary orbit is also referred to as a geosynchronous earth orbit (GEO). A geostationary satellite station has a relative speed of substantially zero with respect to a terminal device 50 on the ground, and is stationary as viewed from the terminal device 50 on the ground. The non-ground station 304 performs satellite communications with the terminal devices 501, 503, 504, and the like located on the Earth. Figure 4

[0109] A low earth orbit satellite station is a satellite station that operates in a low orbit around the Earth. In the example of FIG. 4, the non-ground station 301 constituting the air-based platform ABP1 is a low earth orbit satellite station. Among satellite orbits, a low earth orbit is an orbit at an altitude of approximately 2,000 km. A low earth orbit satellite station has a relative speed with respect to a terminal device 50 on the ground, and is not stationary as viewed from the terminal device 50 on the ground. The non-ground station 301 performs satellite communications with the terminal devices 501, 502, 503, 504, and the like located on the Earth. Figure 4 ​​In the example, the non-ground stations 301 and 302 constituting the space platform SBP1 are low Earth orbit (LEO) satellite stations. In satellite orbits, LEO is an orbit at an altitude of approximately 2000 km or lower (e.g., from 100 km to 2000 km). LEO is also called Low Earth Orbit (LEO). Unlike geostationary satellite stations, LEO satellite stations have a relative velocity with the ground-based terminal equipment 50 and appear to be moving from the perspective of the ground-based terminal equipment 50. Non-ground stations 301 and 302 each form a cell and communicate via satellite with terminal equipment 501, 503, 504, etc., located on Earth.

[0110] It should be noted that, Figure 4 Only two non-ground stations, 301 and 302, are shown as satellite stations constituting the SBP1 space platform. However, in practice, a satellite constellation is formed by many satellite stations. In this case, the number of satellite stations constituting the SBP1 space platform is three or more (e.g., dozens to thousands).

[0111] It should be noted that, although Figure 4 The examples shown as satellite stations are only geostationary satellite stations and low Earth orbit (LEO) satellite stations, but the satellite stations constituting communication system 1 may include medium Earth orbit (MEO) satellite stations. A MEO satellite station is a satellite station operating in a medium Earth orbit around the Earth. A MEO is an orbit located between low Earth orbit (LEO) and geostationary orbit. MEO is also called a medium Earth orbit (MEO). Furthermore, the satellite stations constituting communication system 1 may include highly elliptical orbit (HEO) satellite stations. It should be noted that the satellite stations forming a satellite constellation may include not only LEO satellite stations, but also MEO, HEO, and geostationary satellite stations. The satellite stations may include very low Earth orbit (VLEO) satellite stations. A VLEO satellite station is a satellite station operating in a very low Earth orbit (VLEO) around the Earth.

[0112] Figure 5 This is an illustration showing an example of a cellular network formed by non-geosynchronous satellites. Figure 5 The cell C formed by non-ground station 302 is shown. Figure 5 In the example, non-ground station 302 is a low Earth orbit satellite station (or a very low Earth orbit satellite station). The satellite station, operating in low Earth orbit, communicates with ground-based terminal equipment 50 in a predetermined direction relative to the ground. For example, in Figure 5 In the example shown, angle R is 40°. Figure 5In the example of FIG. 3, the radius D of the cell C formed by the non-terrestrial station 302 is, for example, 1000 km. The low earth orbit satellite station moves at a constant speed. In a case where it is difficult for the low earth orbit satellite station to provide satellite communication to the terminal device 50 on the ground, a succeeding low earth orbit satellite station (a neighboring satellite station) provides satellite communication. In Figure 5 In the example of FIG. 3, in a case where it is difficult for the non-terrestrial station 302 to provide satellite communication to the terminal device 50 on the ground, a succeeding non-terrestrial station 303 provides satellite communication. It should be noted that the numerical values of the angle R and the radius D described above are merely examples and are not limiting.

[0113] The medium earth orbit satellite and the low earth orbit satellite move in an orbit in the sky at a very high speed. For example, the low earth orbit satellite at an altitude of 600 km moves in an orbit at a speed of 7.6 km / S. The low earth orbit satellite forms a cell (or a beam) having a radius of several tens of km to several hundred km on the ground, but the cell formed on the ground also moves according to the movement of the satellite, so handover can have to be performed even when the terminal device on the ground does not move. For example, assuming that the cell formed on the ground has a diameter of 50 km and the terminal device on the ground does not move, handover occurs in about 6 to 7 seconds.

[0114] As described above, the terminal device 50 can perform radio communication using a non-terrestrial network. The non-terrestrial station 30 of the communication system 1 constitutes the non-terrestrial network. Accordingly, the communication system 1 can extend services to the terminal device 50 located in an area that cannot be covered by the terrestrial network.

[0115] For example, the communication system 1 can provide public safety communication and critical communication to communication devices such as Internet of Things (IoT) devices and Machine Type Communication (MTC) devices. By using the non-terrestrial network, service reliability and recoverability are improved, so the communication system 1 can reduce vulnerability of services to physical attacks or natural disasters. The communication system 1 can also realize service connection to airplane passengers and aircraft terminal devices such as drones, and service connection to mobile terminal devices such as ships and trains. Furthermore, the communication system 1 can provide A / V content, group communication, IoT broadcast service, software download service, high-efficiency multicast service such as emergency messages, high-efficiency broadcast service, and the like. In addition, the communication system 1 can also realize offloading of communication traffic between the terrestrial network and the non-terrestrial network.

[0116] In order to realize the foregoing, it is desirable to integrate the operation of the non-terrestrial network provided by the communication system 1 with the operation of the terrestrial network in a higher layer. It is desirable for the non-terrestrial network provided by the communication system 1 to share a common radio access scheme with the terrestrial network.

[0117] It should be noted that the devices in the drawings can be regarded as logical devices. In other words, some of the devices in the drawings can be implemented by virtual machines (VMs), containers (e.g., container Docker), and the like, and these devices can be implemented on physically identical hardware.

[0118] In the present embodiment, the ground station and the non-ground station can also be referred to as base stations. The satellite station can also be referred to as a relay station. In a case where the satellite station has a function as a base station, the satellite station can also be referred to as a base station.

[0119] It should be noted that, in the following description, the terminal device can also be referred to as a user equipment (UE). The terminal device is a type of communication device, and is also referred to as a mobile station or a terminal.

[0120] In the present embodiment, the concept of a communication device includes not only a portable mobile device such as a mobile terminal (terminal device), but also a device installed in a structure or a moving body. The structure or the moving body itself can be regarded as a communication device. The concept of a communication device includes not only a terminal device, but also a base station and a relay station. The communication device is a type of processing device and an information processing device. The communication device can also be referred to as a transmission device or a reception device.

[0121] Hereinafter, the configuration of each device constituting the communication system 1 will be described in detail. It should be noted that the configuration of each device described below is merely an example. The configuration of each device can be different from the configuration described below.

[0122] 2-1. Configuration Example of Management Device

[0123] The configuration of the management device 10 will now be described.

[0124] The management device 10 is a device that manages a radio network. For example, the management device 10 is a device that constitutes a core network. In a case where the core network is an EPC, the management device 10 is, for example, a device having a function as a mobility management entity (MME). In a case where the core network is a 5GC, the management device 10 is, for example, a device having a function as an access and mobility management function (AMF) and / or a session management function (SMF). The MME, the AMF, and the SMF are control plane network function nodes in the core network. The management device 10 can have a device as a control plane network function (6G CPNF) in 6G. The 6G CPNF can include one or a plurality of logical nodes.

[0125] Of course, the functions of the management apparatus 10 are not limited to the MME, the AMF, the SMF, and the 6G CPNF. For example, in the case where the core network is a 5GC, the management apparatus 10 can be an apparatus having functions as a network slice selection function (NSSF), an authentication server function (AUSF), a policy control function (PCF), and a unified data management (UDM). The management apparatus 10 can also be an apparatus having a function as a home subscriber server (HSS).

[0126] It should be noted that the management apparatus 10 can have a function of a gateway. For example, the management apparatus 10 can have a function as a serving gateway (S-GW) or a packet data network gateway (P-GW). The management apparatus 10 can also have a function of a user plane function (UPF). At this time, the management apparatus 10 can include a plurality of UPFs. The management apparatus 10 can also be an apparatus having a function as a user plane network function (6G UPNF) in 6G.

[0127] The core network includes a plurality of network functions, each of which can be integrated into one physical apparatus or can be distributed to a plurality of physical apparatuses. In other words, the management apparatus 10 can be distributed and assigned in a plurality of apparatuses. Furthermore, this distributed assignment can be controlled to be performed dynamically. The base station (the terrestrial station 20 and / or the non-terrestrial station 30) and the management apparatus 10 constitute a network, and provide a radio communication service for the terminal apparatus 50. The management apparatus 10 is connected to a network PN such as the Internet. The terminal apparatus 50 can use various services provided through the network PN.

[0128] It should be noted that the management apparatus 10 does not necessarily need to be an apparatus constituting the core network. For example, assume that the core network is a wideband code division multiple access (W-CDMA) or code division multiple access 2000 (cdma 2000) core network. At this time, the management apparatus 10 can be an apparatus functioning as a radio network controller (RNC).

[0129] Figure 6 is a diagram showing a configuration example of the management apparatus 10 according to an embodiment of the present disclosure. The management apparatus 10 includes a communication portion 11, a storage portion 12, and a control portion 13. It should be noted that, Figure 6 The configuration shown in is a functional configuration, and can be different from a hardware configuration. The functions of the management apparatus 10 can be implemented in a plurality of physically separate configurations in a distributed manner. For example, the management apparatus 10 can include a plurality of server apparatuses.

[0130] The communication section 11 is a communication interface for communicating with other devices. The communication section 11 can be a network interface or a device connection interface. For example, the communication section 11 can be a local area network (LAN) interface such as a network interface card (NIC), or can be a universal serial bus (USB) interface including a USB host controller, a USB port, and the like. The communication section 11 can also be a wired interface or a wireless interface. The communication section 11 functions as a communication means of the management device 10. The communication section 11 communicates with the ground station 20 and the like in accordance with the control of the control section 13.

[0131] The storage section 12 is a storage device capable of data read and data write, such as a dynamic random access memory (DRAM), a static random access memory (SRAM), a flash memory, or a hard disk. The storage section 12 functions as a storage means in the management device 10. The storage section 12 stores, for example, the connection state of the terminal device 50. For example, the storage section 12 stores the state of radio resource control (RRC) and the state of EPS connection management (ECM) of the terminal device 50. The storage section 12 can function as a home storage that stores the location information of the terminal device 50.

[0132] The control section 13 is a controller that controls each section of the management device 10. The control section 13 is realized by, for example, a processor such as a central processing unit (CPU), a micro processing unit (MPU), or a graphic processing unit (GPU). For example, the control section 13 is realized by executing various programs stored in a storage device inside the management device 10 by a processor using a random access memory (RAM) or the like as a work area. It should be noted that the control section 13 can be realized by an integrated circuit such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). The control section 13 can also be realized by a GPU. Any one of the CPU, the MPU, the ASIC, the FPGA, and the GPU can be regarded as a controller. It should be noted that the control section 13 can include a plurality of physically separated objects. For example, the control section 13 can include a plurality of semiconductor chips.

[0133] It should be noted that the operation of the control section 13 can be similar to the operation of the control section 23 of the ground station 20, or can be similar to the operation of the control section 33 of the non-ground station 30. Furthermore, the operation of the control section 13 can be similar to the operation of the control section 43 of the relay station 40, or can be similar to the operation of the control section 53 of the terminal device 50.

[0134] 2-2, Configuration Example of Ground Station

[0135] The configuration of the ground station 20 will be described first.

[0136] The ground station 20 is a communication device located on the ground. For example, the ground station 20 is a radio communication device that performs radio communication with the terminal device 50. The ground station 20 can be configured to perform radio communication with the terminal device 50 through the non-ground station 30, or can be configured to perform radio communication with the terminal device 50 through a relay station on the ground. Of course, the ground station 20 can be configured to directly perform radio communication with the terminal device 50.

[0137] Figure 7 is a diagram illustrating a configuration example of the ground station 20 according to an embodiment of the present disclosure. The ground station 20 includes a radio communication section 21, a storage section 22, a control section 23, and a network communication section 24. Figure 7 The configuration illustrated in FIG. 10 is a functional configuration, and can be different from a hardware configuration. The functions of the ground station 20 can be implemented in a plurality of physically separate configurations in a distributed manner.

[0138] The radio communication section 21 is a signal processing section for performing radio communication with other radio communication devices (e.g., the non-ground station 30, the relay station 40, the terminal device 50, and another ground station 20). The radio communication section 21 operates in accordance with the control of the control section 23. The radio communication section 21 supports one or more radio access schemes. For example, the radio communication section 21 supports at least one of NR, LTE, or 6G. In addition to NR, LTE, and 6G, the radio communication section 21 can support W-CDMA and / or cdma 2000. The radio communication section 21 can also support an automatic retransmission technique such as Hybrid Automatic Repeat reQuest (HARQ).

[0139] The radio communication section 21 includes a reception processing section 211, a transmission processing section 212, and an antenna 213. The radio communication section 21 can include a plurality of reception processing sections 211, a plurality of transmission processing sections 212, and a plurality of antennas 213. It should be noted that, in the case where the radio communication section 21 supports a plurality of radio access schemes, each of the sections of the radio communication section 21 can be configured separately for each radio access scheme. For example, the reception processing section 211 and the transmission processing section 212 can be configured separately for each of LTE, NR, and 6G. The antenna 213 can include a plurality of antenna elements (e.g., a plurality of patch antennas). At this time, the radio communication section 21 can be configured to be capable of beamforming. The radio communication section 21 can be configured to be capable of polarization beamforming using a vertical polarization wave (V-polarization wave) and a horizontal polarization wave (H-polarization wave).

[0140] The reception processing section 211 performs processing on the uplink signal received through the antenna 213. For example, the reception processing section 211 performs down-conversion, removal of unnecessary frequency components, control of amplification level, quadrature demodulation, conversion into a digital signal, removal of a guard interval (cyclic prefix), frequency-domain signal extraction by a fast Fourier transform, and the like on the uplink signal. Subsequently, the reception processing section 211 separates an uplink channel (such as a physical uplink shared channel (PUSCH) or a physical uplink control channel (PUCCH)) and an uplink reference signal from the signal subjected to the processing described above. The reception processing section 211 demodulates the received signal by using a modulation scheme such as binary phase shift keying (BPSK) or quadrature phase shift keying (QPSK) for the modulation symbols of the uplink channel. The modulation method used for demodulation can be 16 quadrature amplitude modulation (QAM), 64 QAM, 256 QAM, or 1024 QAM. At this time, the signal points on the constellation diagram do not necessarily have to be equidistant. The constellation diagram can be a non-uniform constellation diagram (NUC). Subsequently, the reception processing section 211 performs decoding processing on the encoded bits of the demodulated uplink channel. The decoded uplink data and uplink control information are output to the control section 23.

[0141] The transmission processing section 212 performs transmission processing of downlink control information and downlink data. For example, the transmission processing section 212 encodes the downlink control information and downlink data received from the control section 23 using an encoding scheme such as block coding, convolutional coding, or turbo coding. Here, the encoding can be based on, for example, a polar code or a low-density parity-check code (LDPC code). Subsequently, the transmission processing section 212 modulates the encoded bits by a predetermined modulation scheme such as BPSK, QPSK, 16 QAM, 64 QAM, 256 QAM, or 1024 QAM. At this time, the signal points on the constellation diagram do not necessarily have to be equidistant. The constellation diagram can be a non-uniform constellation diagram (NUC). Subsequently, the transmission processing section 212 multiplexes the modulation symbols of each channel and a downlink reference signal, and allocates the multiplexed modulation symbols and downlink reference signal in a predetermined resource unit. Subsequently, the transmission processing section 212 performs various types of signal processing on the multiplexed signal. For example, the transmission processing section 212 performs processing such as conversion to the time domain by a fast Fourier transform, addition of a guard interval (cyclic prefix), generation of a baseband digital signal, conversion into an analog signal, quadrature modulation, up-conversion, removal of unnecessary frequency components, and power amplification. The signal generated by the transmission processing section 212 is transmitted from the antenna 213.

[0142] The antenna 213 is an antenna device (antenna portion) that converts electric current into radio waves and converts radio waves into electric current. The antenna 213 can include one antenna element (for example, one patch antenna) or a plurality of antenna elements (for example, a plurality of patch antennas). In a case where the antenna 213 includes a plurality of antenna elements, the radio communication portion 21 can be configured to be capable of beamforming. For example, the radio communication portion 21 can generate a directional beam by controlling the directivity of a radio signal using a plurality of antenna elements. The antenna 213 can be a dual-polarized antenna. In a case where the antenna 213 is a dual-polarized antenna, the radio communication portion 21 can transmit a radio signal using dual-polarized waves including a vertically polarized wave (V-polarized wave) and a horizontally polarized wave (H-polarized wave). In transmitting a radio signal, the radio communication portion 21 can use dual-polarized waves including polarized waves at 45 degrees and -45 degrees from the vertical direction. The radio communication portion 21 can control the directivity of a radio signal transmitted using dual-polarized waves. The radio communication portion 21 can transmit and receive spatially multiplexed signals by a plurality of layers including a plurality of antenna elements.

[0143] The storage portion 22 is a storage device capable of data read and data write, such as a DRAM, an SRAM, a flash memory, or a hard disk. The storage portion 22 functions as a storage of the ground station 20.

[0144] The control portion 23 is a controller that controls each portion of the ground station 20. The control portion 23 is implemented by, for example, a processor such as a CPU, an MPU, or a GPU. For example, the control portion 23 is implemented by executing various programs stored in a storage device inside the ground station 20 by a processor using a RAM or the like as a work area. The control portion 23 can be implemented by an integrated circuit such as an ASIC or an FPGA. The control portion 23 can be implemented by a GPU. Any one of the CPU, the MPU, the ASIC, the FPGA, and the GPU can be regarded as a controller. The control portion 23 can include a plurality of physically separated objects. For example, the control portion 23 can include a plurality of semiconductor chips.

[0145] It should be noted that the operation of the control portion 23 of the ground station 20 can be similar to the operation of the control portion 33 of the non-ground station 30. At this time, the control portion 23 of the ground station 20 can have a configuration similar to the functional blocks (described later) included in the control portion 33 of the non-ground station 30. Of course, the operation of the control portion 33 of the non-ground station 30 can be the same as the operation of the control portion 23 of the ground station 20. Furthermore, the operation of the control portion 23 can be similar to the operation of the control portion 43 of the relay station 40, can be similar to the operation of the control portion 13 of the management device 10, or can be similar to the operation of the control portion 53 of the terminal device 50.

[0146] The network communication section 24 is a communication interface for communicating with other devices. The network communication section 24 is, for example, a network interface. The network communication section 24 is, for example, a LAN interface such as a NIC. The network communication section 24 can be a wired interface or a wireless interface. The network communication section 24 functions as a communication device of the ground station 20. The network communication section 24 communicates with the management device 10, the relay station 40, and the like in accordance with the control of the control section 23.

[0147] 2-3. Configuration Example of Non-ground Station

[0148] The configuration of the non-ground station 30 will now be described.

[0149] In the present embodiment, the non-ground station 30 is a base station that provides a terminal device 50 with the function of a base station. Alternatively, the non-ground station 30 is a relay station that relays communication between the ground station 20 (or another non-ground station 30) and the terminal device 50. The non-ground station 30 can be a satellite station or an aircraft station.

[0150] The satellite station is a satellite station that can float in outer space. The satellite station can be a device installed on a space mobile body such as a man-made satellite, or can be the space mobile body itself. The space mobile body is a mobile body that moves in outer space. Examples of the space mobile body include man-made celestial bodies such as man-made satellites, space ships, space stations, and probes.

[0151] It should be noted that the satellite that functions as the satellite station can be any one of a very low earth orbit satellite, a low earth orbit satellite, a medium earth orbit satellite, and a geostationary satellite. The satellite that functions as the satellite station can also be a high elliptical orbit satellite that orbits a high elliptical orbit (HEO). The satellite station can be a communication device installed on these satellites.

[0152] The aircraft station is a radio communication device that can float in the atmosphere, such as an aircraft. The aircraft station can be a device installed on an aircraft or the like, or can be the aircraft itself. It should be noted that the concept of an aircraft includes not only aircrafts that are heavier than air such as airplanes and gliders, but also aircrafts that are lighter than air such as balloons and airships. The concept of an aircraft includes not only aircrafts that are heavier than air and aircrafts that are lighter than air, but also rotary-wing aircrafts such as helicopters and autogyros. It should be noted that the aircraft station (or the aircraft on which the aircraft station is installed) can be an unmanned aerial vehicle (UAV) such as a drone.

[0153] It should be noted that the concept of unmanned aerial vehicle includes unmanned aircraft system (UAS) and tethered unmanned aircraft system (tethered UAS). The concept of unmanned aerial vehicle includes lighter-than-air (LTA) UAS and heavier-than-air (HTA) UAS. In addition, the concept of unmanned aerial vehicle includes high-altitude UAS platforms (HAPs).

[0154] Figure 8 is a diagram showing a configuration example of the non-ground station 30 according to an embodiment of the present disclosure. The non-ground station 30 includes a radio communication part 31, a storage part 32, and a control part 33. Figure 8 The configuration shown in FIG. 1 is a functional configuration, and can be different from a hardware configuration. The functions of the non-ground station 30 can be implemented in a plurality of physically separate configurations in a distributed manner.

[0155] The radio communication part 31 is a radio communication interface for implementing radio communication with other radio communication apparatuses (e.g., the ground station 20, the relay station 40, the terminal apparatus 50, and another non-ground station 30). The radio communication part 31 supports one or more radio access schemes. For example, the radio communication part 31 supports at least one of NR, LTE, or 6G. In addition to NR, LTE, and 6G, the radio communication part 31 can support W-CDMA and / or cdma 3000.

[0156] The radio communication part 31 includes a reception processing part 311, a transmission processing part 312, and an antenna 313. The radio communication part 31 can include a plurality of reception processing parts 311, a plurality of transmission processing parts 312, and a plurality of antennas 313. It should be noted that, in a case where the radio communication part 31 supports a plurality of radio access schemes, each of the parts of the radio communication part 31 can be configured separately for each radio access scheme. For example, the reception processing part 311 and the transmission processing part 312 can be configured separately for each of LTE, NR, and 6G. The configuration of the reception processing part 311, the transmission processing part 312, and the antenna 313 is similar to that of the reception processing part 211, the transmission processing part 212, and the antenna 213 described earlier. It should be noted that, similarly to the radio communication part 21, the radio communication part 31 can be configured to be capable of beamforming. At this time, similarly to the radio communication part 21, the radio communication part 31 can be configured to be capable of polarization beamforming. Similarly to the radio communication part 21, the radio communication part 31 can also be configured to be capable of transmitting and receiving spatially multiplexed signals.

[0157] The storage part 32 is a storage apparatus capable of data read and data write, such as DRAM, SRAM, flash memory, or a hard disk. The storage part 32 functions as a storage of the non-ground station 30.

[0158] The control section 33 is a controller that controls each section of the non-ground station 30. The control section 33 is implemented by, for example, a processor such as a CPU, an MPU, or a GPU. For example, the control section 33 is implemented by executing various programs stored in a storage device inside the non-ground station 30 by a processor using a RAM or the like as a work area. Note that the control section 33 can be implemented by an integrated circuit such as an ASIC or an FPGA. The control section 33 can also be implemented by a GPU. Any one of a CPU, an MPU, an ASIC, an FPGA, and a GPU can be regarded as a controller. Note that the control section 33 can include a plurality of physically separate objects. For example, the control section 33 can include a plurality of semiconductor chips.

[0159] The control section 33 includes a notification section 331, a reception section 332, a transmission section 333, and a communication control section 334. Each block (the notification section 331 to the communication control section 334) that constitutes the control section 33 is a functional block that indicates a function of the control section 33, respectively. The functional blocks can be software blocks or hardware blocks. For example, each of the functional blocks described above can be a software module implemented by software (including microprograms), or can be a circuit block on a semiconductor chip (a die). Of course, each of the functional blocks can be a processor or an integrated circuit. The control section 33 can include functional units different from the functional blocks described above. The method of configuring the functional blocks is arbitrary.

[0160] Note that the operation of the control section 33 can be similar to the operation of the control section 53 of the terminal device 50. Further, the operation of the control section 33 can be similar to the operation of the control section 13 of the management device 10, can be similar to the operation of the control section 23 of the ground station 20, or can be similar to the operation of the control section 43 of the relay station 40.

[0161] 2-4, Configuration Example of Base Station

[0162] At least one of the ground station 20 or the non-ground station 30 can operate as a base station. In the case where the ground station 20 is a base station, the non-ground station 30 can function as a relay station that relays communication between the base station and the terminal device 50. The ground station 20 can also function as a relay station that relays communication between the base station and the terminal device 50. In the case where the ground station 20 and / or the non-ground station 30 is used as a relay station, the configuration of the ground station 20 and / or the non-ground station 30 can be similar to the configuration of the relay station 40 described later. A base station will be described hereinafter.

[0163] A base station is a device corresponding to a radio base station (base station, Node B, eNB, gNB, 6GNB, etc.) or a radio access point. The base station can be a radio relay station. The base station can be an optical expansion device called a remote radio head (RRH). The base station can be a receiving station such as a field pickup unit (FPU). The base station can be an integrated access and backhaul (IAB) donor node or an IAB relay node that provides a radio access line and a radio backhaul line by time division multiplexing, frequency division multiplexing, or space division multiplexing.

[0164] It should be noted that the radio access technology used by the base station can be a cellular communication technology or a wireless LAN technology. Of course, the radio access technology used by the base station is not limited to the technologies described above, and can be any other radio access technology. For example, the radio access technology used by the base station can be a low-power wide-area (LPWA) communication technology. The radio communication used by the base station can be radio communication using millimeter waves or radio communication using terahertz waves. The radio communication used by the base station can be radio communication using radio waves or radio communication using infrared rays or visible light (optical radio communication).

[0165] The base station according to the present embodiment can be capable of non-orthogonal multiple access (NOMA) communication with another communication device (for example, the terminal device 50). Here, the NOMA communication is communication (transmission, reception, or both) using a non-orthogonal resource. It should be noted that the base station can be capable of NOMA communication with another base station. Here, the non-orthogonal resource is a resource (time, frequency, and space) on an axis different from an orthogonal resource, and is, for example, a radio resource capable of separating different signals using scrambling, interleaving, codes (for example, spreading codes, sparse codes, etc.), power differences, and the like.

[0166] The base station according to the present embodiment can be capable of intercommunication with a core network through a base station-core network interface (for example, an S1 interface, etc.). The interface can be a wired or wireless interface. The base station can be capable of intercommunication with another base station through an inter-base station interface (for example, an X2 interface, an Xn interface, an X2 interface, an F1 interface, etc.). The interface can be a wired or wireless interface.

[0167] It should be noted that the concept of a base station (also referred to as a base station device) includes not only a donor base station but also a relay base station (also referred to as a relay station). At this time, the relay base station can be any one of an RF repeater, a smart repeater, and a smart surface. The concept of a base station includes not only a structure having the function of a base station but also a device installed in a structure.

[0168] The structure is, for example, a building such as a high-rise building, a house, a steel tower, a station facility, an airport facility, a port facility, an office building, a school building, a hospital, a factory, a commercial facility, or a stadium. The concept of a structure includes not only a building but also a non-building structure such as a tunnel, a bridge, a dam, a fence, or a pole, and equipment such as a crane, a gate, or a windmill. The concept of a structure includes not only a structure on land (narrowly, on the ground) or underground but also a structure on water such as a breakwater or an ultra-large floating body, and a structure under water such as an ocean observation facility. The base station can also be referred to as an information processing apparatus.

[0169] The base station can be a donor station or a relay station. The base station can also be a fixed station or a mobile station. A mobile station is a radio communication apparatus configured to be movable (for example, a base station). At this time, the base station can be an apparatus installed in a moving body, or can be the moving body itself. For example, a relay station having mobility can be regarded as a base station as a mobile station. The base station as a mobile station also corresponds to an apparatus originally having mobility and having a function of a base station (at least some of the functions of a base station), such as a vehicle, an unmanned aerial vehicle (UAV), or a smartphone. An example of the UAV is a drone.

[0170] Here, the moving body can be a mobile terminal such as a smartphone or a mobile phone. The moving body can also be a moving body on land (narrowly, on the ground) (such as a vehicle such as a car, a bicycle, a bus, a truck, a motorcycle, a train, or a linear motor car), or can be a moving body underground (for example, in a tunnel) (for example, a subway). The moving body can also be a moving body on water (such as a ship such as a passenger ship, a cargo ship, or a hovercraft), or can be a moving body under water (such as a submersible such as a semi-submersible ship, a submarine, or an unmanned underwater vehicle). The moving body can also be a moving body in the atmosphere (such as an aircraft such as an airplane, a dirigible, or a drone). The moving body can also be capable of floating in the air or in space.

[0171] The base station can be a ground base station (a ground station) installed on the ground. For example, the base station can be a base station disposed in a structure on the ground, or can be a base station installed in a moving body moving on the ground. More specifically, the base station can be an antenna installed in a structure such as a building and a signal processing apparatus connected to the antenna. Of course, the base station can be the structure or the moving body itself. The term "on the ground" means not only on land (narrowly, on the ground) but also on the ground in a broad sense, including underground, on water, and under water. It should be noted that the base station is not limited to a ground base station. For example, in the case where the communication system 1 is a satellite communication system, the base station can be an aircraft station. From the perspective of a satellite station, an aircraft station located on the Earth is a ground station.

[0172] The base station is not limited to a ground station. The base station can be a non-ground base station device (non-ground station) capable of floating in the air or in space. At this time, the base station can be an aircraft station or a satellite station.

[0173] The size of the coverage of the base station can range from large (such as a macro cell) to small (such as a pico cell). Of course, the size of the coverage of the base station can be very small, such as a femto cell. The base station can have a beamforming capability. In this case, the base station can form a cell or a service area for each beam. To this end, the base station can be equipped with an antenna array including a plurality of antenna elements, and can be configured to provide advanced antenna technologies represented by multiple input multiple output (MIMO) and beamforming.

[0174] In addition to beamforming that allows a beam to have directionality, by further considering distance information from the antennas of the base station, the base station can have a function of delivering a desired wave to a predetermined point in a point-by-point manner. This function can be referred to as beam focusing or point forming.

[0175] In the present embodiment, the base station can include a set of a plurality of physical or logical devices. For example, in the present embodiment, the base station can be divided into a plurality of devices such as a baseband unit (BBU) and a radio unit (RU), and can be interpreted as an aggregation of the plurality of devices. In the embodiment of the present disclosure, the base station can be one or both of the BBU and the RU.

[0176] The BBU and the RU can be connected through a predetermined interface (for example, eCPRI). The RU can be referred to as a remote radio unit (RRU) or a radio DoT (RD). The RU can correspond to a gNB-DU (gNB distributed unit) described later. The BBU can correspond to a gNB-CU (gNB central unit) described later. The RU can be a radio device connected to the gNB-DU described later. The gNB-CU, the gNB-DU, and the RU connected to the gNB-DU can be configured to comply with open radio access network (O-RAN). The RU can be a device integrated with an antenna.

[0177] The antenna included in the base station (for example, the antenna integrated with the RU) can employ an advanced antenna system and support MIMO (for example, FD-MIMO) and beamforming. In this case, the antenna included in the base station (for example, the antenna integrated with the RU) can include, for example, 64 transmission antenna ports and 64 reception antenna ports.

[0178] The antenna installed on the RU can be an antenna panel including one or more antenna elements, and the RU can be equipped with one or more antenna panels. For example, the RU can be equipped with two types of antenna panels as horizontal polarization antenna panels and vertical polarization antenna panels, or as right-hand circular polarization antenna panels and left-hand circular polarization antenna panels. The RU can form and control independent beams for each antenna panel.

[0179] It should be noted that multiple base stations can be connected to each other. One or more base stations can be included in a radio access network (RAN). That is, a base station can be simply referred to as a RAN, a RAN node, an access network (AN), or an AN node. The RAN in LTE is referred to as an enhanced universal terrestrial RAN (EUTRAN). The RAN in NR is referred to as an NGRAN. The RAN in W-CDMA (UMTS) is referred to as a UTRAN.

[0180] A base station in LTE is sometimes referred to as an evolved node B (eNodeB) or eNB. At this time, the EUTRAN includes one or more eNodeBs (eNBs). A base station in NR can be referred to as a gNodeB or gNB. At this time, the NGRAN includes one or more gNBs. A base station in 6G can be referred to as a 6GNodeB, 6gNodeB, 6GNB, or 6gNB. At this time, the 6GRAN includes one or more 6GNBs. The EUTRAN can include a gNB (en-gNB) connected to a core network (EPC) in an LTE communication system (EPS). Similarly, the NGRAN can include an ng-eNB connected to a core network 5GC in a 5G communication system (5GS).

[0181] It should be noted that, in the case of a base station being an eNB, a gNB, or a 6GNB, the base station can be referred to as a 3GPP access. In the case of a base station being a radio access point, the base station can be referred to as a non-3GPP access. The base station can also be an optical expansion device referred to as a remote radio head (RRH) or a radio unit (RU). In the case of a base station being a gNB, the base station can be a combination of the gNB central unit (CU) and the gNB distributed unit (DU) described earlier, or can be either one of them.

[0182] Here, the gNB-CU hosts multiple upper layers among the access layers for communication with the UE. Here, the upper layers are, for example, radio link control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol (PDCP). On the other hand, the gNB-DU hosts multiple lower layers among the access layers. Here, the lower layers are, for example, radio link control (RLC), medium access control (MAC), and physical layer (PHY). That is, the gNB-CU can generate some of the messages / information as RRC signaling (semi-statically informed), and the gNB-DU can generate the remaining messages / information as MAC CE or DCI (dynamically informed). In the RRC configuration (quasi-statically informed), the gNB-DU can generate some of the configurations, such as the IE: cellGroupConfig, and the gNB-CU can generate the remaining configurations. These configurations can be transmitted and received through the F1 interface.

[0183] The base stations can be configured to be able to communicate with another base station. For example, in the case of a combination of multiple base stations being eNBs or a combination of eNBs and en-gNBs, the respective base stations can be connected through an X2 interface. In the case of a combination of multiple base stations being gNBs or a combination of ng-eNBs and gNBs, the devices can be connected through an Xn interface. In the case of a combination of multiple base stations being a gNB central unit (CU) and a gNB distributed unit (DU), the devices can be connected through the F1 interface described above. The multiple base stations can transmit messages / information (e.g., RRC signaling, MAC control element (CE), or downlink control information (DCI)) described later, for example, through the X2, Xn, or F1 interface.

[0184] For example, in the embodiments described later, the ground station and the non-ground station can both be gNBs or both be eNBs. In the embodiments described later, one of the ground station and the non-ground station can be a gNB, and the other can be an eNB. In the embodiments described later, one of the ground station and the non-ground station can be a gNB-CU, and the other can be a gNB-DU. In the case of the non-ground station being a gNB and the ground station being an eNB, the gNB of the non-ground station (satellite station) can implement connection mobility (handover) or dual connectivity through coordination (e.g., X2 signaling, Xn signaling) with the eNB of the ground station. In the case of the non-ground station being a gNB-DU and the ground station being a gNB-CU, the gNB-DU of the non-ground station (e.g., satellite station) can constitute a logical gNB through coordination (e.g., F1 signaling) with the gNB-CU of the ground station.

[0185] The cell provided by the base station is referred to as a serving cell. The serving cell includes a primary cell (PCell) and a secondary cell (SCell). In a case where dual connectivity is configured for a UE (e.g., the terminal device 50), the PCell and zero or one or more SCells provided by a master node (MN) can be referred to as a master cell group. Examples of dual connectivity include EUTRA-EUTRA dual connectivity, EUTRA-NR dual connectivity (ENDC), EUTRA-NR dual connectivity with 5GC, NR-EUTRA dual connectivity (NEDC), and NR-NR dual connectivity (NNDC). Examples of dual connectivity also include NR-6G dual connectivity and 6G-NR dual connectivity.

[0186] It should be noted that the serving cell can include a primary secondary cell or a primary SCG cell (PSCell). That is, in a case where dual connectivity is configured for a UE, the PSCell and zero or one or more SCells provided by a secondary node (SN) can be referred to as a secondary cell group (SCG).

[0187] A physical uplink control channel (PUCCH) is transmitted in the PCell and the PSCell, but not in the SCell, unless a special configuration (e.g., PUCCH on SCell) is provided. Radio link failure is also detected in the PCell and the PSCell, but not in the SCell (may not need to be detected). As described earlier, the PCell and the PSCell have a special role in the serving cell, and are therefore also referred to as special cells (SpCell).

[0188] One cell can be associated with one downlink component carrier and one uplink component carrier. The system bandwidth corresponding to one cell can be divided into a plurality of bandwidth parts (BWPs). At this time, one or more BWPs can be configured for a UE, and one BWP can be used as an active BWP for a UE. The radio resources (e.g., frequency band, numerology (subcarrier spacing), and slot format (slot configuration)) that can be used by the terminal device 50 can be different for each cell, each component carrier, or each BWP.

[0189] 2-5, Configuration Example of Relay Station

[0190] The configuration of the relay station 40 will now be described.

[0191] The repeater station 40 is a radio communication device that performs radio communication with other communication devices such as the management device 10, the ground station 20, the non-ground station 30, and the terminal device 50. The repeater station 40 relays communication between the non-ground station 30 and a communication device on the ground, such as the management device 10, the ground station 20, or the terminal device 50. The repeater station 40 can be a ground station or a non-ground station. At this time, the repeater station 40 can have a similar configuration to the ground station 20 or can have a similar configuration to the non-ground station 30.

[0192] The repeater station 40 of the present embodiment is, for example, a layer 3 repeater, and is different from a known layer 1 repeater that only amplifies the power of a received RF signal. Here, the layer 3 repeater is a repeater that can decode up to the layer 3. It should be noted that the repeater station 40 can be a smart repeater. Unlike the known layer 1 repeater, the smart repeater is a repeater that is also capable of controlling a physical layer (PHY) or the like. Furthermore, other descriptions indicating a repeater station such as a repeater or a relay device can be substituted for the description of the repeater station appearing in the following description.

[0193] It should be noted that the repeater station 40 can be a fixed device or a movable device. At this time, the repeater station 40 can be a floatable device. The coverage of the repeater station 40 is not limited to a specific size. For example, a cell covered by the repeater station 40 can be a macro cell, a micro cell, or a small cell. Of course, the size of the coverage of the repeater station 40 can be very small, such as a femto cell. The repeater station 40 can also have a beamforming capability. At this time, the repeater station 40 can include a cell or a service area formed for each beam.

[0194] The repeater station 40 is not limited to a device on which the repeater station 40 is installed, as long as the repeater function is satisfied. For example, the repeater station 40 can be installed on a terminal device such as a smartphone, can be installed on a vehicle such as a car, a train, or a rickshaw, can be installed on a flying object (floatable object) such as a balloon, an airplane, or a drone, can be installed on equipment such as a traffic light, a signboard, or a street lamp, or can be installed on a home appliance such as a television, a game console, an air conditioner, a refrigerator, or a lighting fixture. The repeater station can also be provided on an outer wall of a building structure such as a building. With the repeater station provided on the outer wall of the building, even in a case where there is a shielding object between a base station and a terminal device, a signal from the base station can be transmitted through the repeater station provided on the outer wall of the building and reach the terminal device.

[0195] Further, similarly to the base station described earlier, the relay station 40 can be a device installed in a mobile body, or can be the mobile body itself. As described earlier, the mobile body can be a mobile terminal such as a smartphone or a mobile phone. The mobile body can also be a mobile body that moves on land (narrowly, on the ground), or can move underground. Of course, the mobile body can move on water or can move underwater. Further, the mobile body can move within the atmosphere or can move in outer space. The relay station 40 can be a ground station device or a non-ground station device. At this time, the relay station 40 can be an aircraft station or a satellite station.

[0196] The relay station 40 can also be an aircraft station or an earth station. An aircraft station is a radio station installed on the ground or on a mobile body that moves on the ground to communicate with an aircraft station. An earth station is a radio station located on the Earth (including in the air) to communicate with a satellite station (space station). The earth station can be a large earth station or a small earth station such as a very small aperture terminal (VSAT).

[0197] Note that the earth station can be a VSAT control earth station (also called a master station or HUB station), or can be a VSAT earth station (also called a slave station). The earth station can also be a radio station installed on a mobile body that moves on the ground. An example of an earth station installed on a ship includes a shipboard earth station (ESV). The earth station can also include an aircraft earth station installed in an aircraft (including a helicopter) and communicating with a satellite station. The earth station can also include an aeronautical earth station installed in a mobile body that moves on the ground and communicating with an aircraft earth station through a satellite station.

[0198] Note that the relay station 40 can be a portable radio station that communicates with a satellite station or an aircraft station.

[0199] Figure 9 is a diagram showing a configuration example of the relay station 40 according to an embodiment of the present disclosure. The relay station 40 includes a radio communication section 41, a storage section 42, a control section 43, and a network communication section 44. Note that, Figure 9 The configuration shown in the diagram is a functional configuration, and can be different from a hardware configuration. The functions of the relay station 40 can be distributed in a plurality of physically separate configurations in a distributed manner.

[0200] The radio communication section 41 is a signal processing section for performing radio communication with other radio communication apparatuses (e.g., the ground station 20, the non-ground station 30, the relay station 40, the terminal apparatus 50, and another relay station 40). The radio communication section 41 operates in accordance with the control of the control section 43. The radio communication section 41 includes a reception processing section 411, a transmission processing section 412, and an antenna 413. The configuration of the radio communication section 41, the reception processing section 411, the transmission processing section 412, and the antenna 413 can be similar to that of the radio communication section 21, the reception processing section 211, the transmission processing section 212, and the antenna 213 of the ground station 20. Similarly to the radio communication section 21, the radio communication section 41 can be configured to be capable of beamforming. At this time, similarly to the radio communication section 21, the radio communication section 41 can be configured to be capable of polarization beamforming. Similarly to the radio communication section 21, the radio communication section 41 can also be configured to be capable of transmitting and receiving spatially multiplexed signals.

[0201] The storage section 42 is a storage apparatus capable of reading and writing data, such as a DRAM, an SRAM, a flash memory, or a hard disk. The storage section 42 functions as a storage device of the relay station 40.

[0202] The control section 43 is a controller that controls each section of the relay station 40. The control section 43 is implemented by, for example, a processor such as a CPU, an MPU, or a GPU. For example, the control section 43 is implemented by executing various programs stored in a storage apparatus inside the relay station 40 by a processor using a RAM or the like as a work area. It should be noted that the control section 43 can be implemented by an integrated circuit such as an ASIC or an FPGA. The control section 43 can also be implemented by a GPU. Any one of the CPU, the MPU, the ASIC, the FPGA, and the GPU can be regarded as a controller. It should be noted that the control section 43 can include a plurality of physically separate objects. For example, the control section 43 can include a plurality of semiconductor chips.

[0203] It should be noted that the operation of the control section 43 of the relay station 40 can be similar to that of the control section 23 of the ground station 20 or the control section 33 of the non-ground station 30. Conversely, the operation of the control section 23 of the ground station 20 or the control section 33 of the non-ground station 30 can be similar to that of the control section 43 of the relay station 40. Furthermore, the operation of the control section 43 can be similar to that of the control section 13 of the management apparatus 10, or can be similar to that of the control section 53 of the terminal apparatus 50.

[0204] The network communication section 44 is a communication interface for communicating with other devices. The network communication section 44 is, for example, a network interface. The network communication section 44 is, for example, a LAN interface such as a NIC. Note that the network communication section 44 can be a wired interface or a wireless interface. The network communication section 44 functions as a communication means of the relay station 40. The network communication section 44 communicates with the management device 10, the ground station 20, and the like in accordance with the control of the control section 43.

[0205] 2-6. Configuration example of terminal device

[0206] The configuration of the terminal device 50 will now be described.

[0207] The terminal device 50 is a radio communication device that performs radio communication with other communication devices such as the ground station 20 and the non-ground station 30. Any type of computer can be employed as the terminal device 50. The terminal device 50 can be a mobile terminal such as a mobile phone, a smart device (smartphone or tablet device), a personal digital assistant (PDA), or a notebook PC. The terminal device 50 can also be a game machine with a communication function. The terminal device 50 can also be an imaging device (e.g., a camcorder) with a communication function. The terminal device 50 can be a motorcycle, a mobile relay vehicle, or the like installed with a communication equipment such as a field pickup unit (FPU). The terminal device 50 can also be a machine-to-machine (M2M) device or an Internet of Things (IoT) device. The terminal device 50 can also be a wearable device such as a smart watch.

[0208] Note that the terminal device 50 can be an xR device such as an augmented reality (AR) device, a virtual reality (VR) device, or a mixed reality (MR) device. In this case, the xR device can be a glasses-type device such as AR glasses or MR glasses, or can be a head-mounted device such as a VR head-mounted display. In the case where the terminal device 50 is an xR device, the terminal device 50 can be a stand-alone device that includes only a user-wearing portion (e.g., a glasses portion). The terminal device 50 can be a terminal-linked device that includes a user-wearing portion (e.g., a glasses portion) and a terminal portion (e.g., a smart device) linked to the user-wearing portion.

[0209] Note that the terminal device 50 can be configured to be connectable to a plurality of communication paths. For example, the terminal device 50 can be configured to be connectable to both a Wi-Fi (registered trademark) and a cellular network. The terminal device 50 can be connectable to a plurality of cellular networks. In this case, the plurality of cellular networks can include a first cellular network including a terrestrial network and a second cellular network including a non-terrestrial network. In this case, the plurality of cellular networks can be associated with different subscriber identity modules (SIMs).

[0210] It should be noted that the terminal device 50 can be configured to enable switching between use of multiple SIM cards. For example, the terminal device 50 can correspond to a dual-SIM or a triple-SIM. Of course, the terminal device 50 can be configured to allow for insertion of more than three SIM cards into the terminal device 50. The terminal device 50 can also support remote SIM provisioning (RSP). For example, the terminal device 50 can support an embedded SIM (eSIM). An RSP terminal device can rewrite information related to radio communication (hereinafter referred to as a profile) without replacing a SIM card.

[0211] It should be noted that the terminal device 50 can be capable of NOMA communication with the ground station 20. The terminal device 50 can also be capable of using automatic retransmission technology such as HARQ when communicating with the ground station 20. The terminal device 50 can be capable of sidelink communication with another terminal device 50. The terminal device 50 can also be capable of using automatic retransmission technology such as HARQ when implementing sidelink communication. It should be noted that the terminal device 50 can also be capable of NOMA communication in communication with another terminal device 50 (sidelink). The terminal device 50 can also be capable of LPWA communication with other communication devices such as the ground station 20 and another terminal device 50. The radio communication used by the terminal device 50 can be radio communication using millimeter waves. It should be noted that the radio communication used by the terminal device 50 (including sidelink communication) can be radio communication using radio waves, or can be radio communication using infrared rays or visible light (optical radio communication).

[0212] The terminal device 50 can be a mobile device (mobile station). The mobile device is a mobile radio communication device. At this time, the terminal device 50 can be a radio communication device mounted in a mobile body, or can be the mobile body itself. For example, the terminal device 50 can be a vehicle moving on a road, such as an automobile, a bus, a truck, or a motorcycle, can be a vehicle moving on a rail installed on a track (such as a train), or can be a radio communication device mounted on a vehicle. Note that the mobile body can be a mobile terminal such as a smartphone. The mobile body can move on land (narrowly, on the ground), under the ground, on water, or under water. The mobile body can also be a mobile body moving within the atmosphere, such as an aircraft, an airship, a balloon, or a helicopter, or can be a mobile body moving in outer space, such as an artificial satellite. The mobile body can be an unmanned aerial vehicle (UAV) such as a drone. The terminal device 50 can be a radio communication device mounted on a mobile body that is a mobile body moving within the atmosphere, such as an aircraft, an airship, a balloon, or a helicopter, or a mobile body moving in outer space, such as an artificial satellite, or a mobile body such as an unmanned aerial vehicle (UAV), for example, including a drone.

[0213] The terminal device 50 can be connected to multiple base stations or multiple cells at the same time to communicate. For example, in a case where one base station supports a communication area through multiple cells (for example, a pCell and an sCell), the base station and the terminal device 50 can communicate with each other by aggregating multiple cells through a carrier aggregation (CA) technique, a dual connectivity (DC) technique, and / or a multi-connectivity (MC) technique. Alternatively, the terminal device 50 and multiple base stations can communicate with each other through cells of different base stations by a coordinated multipoint transmission and reception (CoMP) technique.

[0214] Figure 10 is a diagram illustrating a configuration example of the terminal device 50 according to an embodiment of the present disclosure. The terminal device 50 includes a radio communication part 51, a storage part 52, and a control part 53. Note that Figure 10 The configuration illustrated in FIG. 10 is a functional configuration, and can be different from a hardware configuration. The functions of the terminal device 50 can also be realized in a plurality of physically separate configurations in a distributed manner.

[0215] The radio communication section 51 is a signal processing section for performing radio communication with other radio communication apparatuses (e.g., the ground station 20, the non-ground station 30, the relay station 40, and another terminal apparatus 50). The radio communication section 51 operates in accordance with the control of the control section 53. The radio communication section 51 includes a reception processing section 511, a transmission processing section 512, and an antenna 513. The configuration of the radio communication section 51, the reception processing section 511, the transmission processing section 512, and the antenna 513 can be similar to that of the radio communication section 21, the reception processing section 211, the transmission processing section 212, and the antenna 213 of the ground station 20. Similarly to the radio communication section 21, the radio communication section 51 can be configured to be capable of beamforming. At this time, similarly to the radio communication section 21, the radio communication section 51 can be configured to be capable of polarization beamforming. Similarly to the radio communication section 21, the radio communication section 51 can also be configured to be capable of transmitting and receiving spatially multiplexed signals.

[0216] The storage section 52 is a storage apparatus capable of reading and writing data, such as a DRAM, an SRAM, a flash memory, or a hard disk. The storage section 52 functions as a storage device of the terminal apparatus 50.

[0217] The control section 53 is a controller that controls each section of the terminal apparatus 50. The control section 53 is implemented by a processor such as a CPU, an MPU, or a GPU. For example, the control section 53 is implemented by executing various programs stored in a storage apparatus inside the terminal apparatus 50 by a processor using a RAM or the like as a work area. It should be noted that the control section 53 can be implemented by an integrated circuit such as an ASIC or an FPGA. The control section 53 can also be implemented by a GPU. Any one of the CPU, the MPU, the ASIC, the FPGA, and the GPU can be regarded as a controller. It should be noted that the control section 53 can include a plurality of physically separate objects. For example, the control section 53 can include a plurality of semiconductor chips.

[0218] The control section 53 includes an acquisition section 531, a configuration section 532, a switching processing section 533, and a communication control section 534. Each block (the acquisition section 531 to the communication control section 534) constituting the control section 53 is a functional block indicating a function of the control section 53. The functional block can be a software block or a hardware block. For example, each functional block described above can be one software module implemented by software (including microprograms), or can be one circuit block on a semiconductor chip (die). Of course, each functional block can be one processor or one integrated circuit. The control section 53 can include a functional unit different from the functional blocks described above. The configuration method of the functional blocks is arbitrary. The operation of each functional block will be described later.

[0219] It should be noted that the operation of each block (acquisition part 531 to communication control part 534) constituting the control part 53 can be similar to that of (notification part 331 to communication control part 334) included in the control part 33 of the non-ground station 30. Further, the operation of the control part 53 can be similar to that of the control part 13 of the management device 10, can be similar to that of the control part 23 of the ground station 20, or can be similar to that of the control part 43 of the relay station 40.

[0220] 3. Basic operation of communication system

[0221] The configuration of the communication system 1 is described above, and the basic operation of the communication system 1 will be described before the operation of the communication system 1 of the present embodiment is described in detail.

[0222] It should be noted that, in the following description, it is assumed that the base station is the non-ground station 30. It should be noted that the non-ground station 30 in the following description can be replaced with the gateway. The non-ground station 30 in the following description can be replaced with the ground station 20 or the relay station 40.

[0223] 3-1. Initial connection processing

[0224] The initial connection processing will be described first.

[0225] The initial connection processing is processing that causes the radio connection state of the terminal device 50 to transition from the unconnected state to the connected state. The unconnected processing is, for example, RRC_IDLE or RRC_INACTIVE. RRC_IDLE is a state in which the terminal device is not connected to any cell, and is also called the idle mode. RRC_INACTIVE is a radio connection state indicating a newly defined inactive state in NR, and is also called the inactive mode. In RRC_INACTIVE, although the terminal device 50 and the base station establish an RRC connection itself between them, the terminal device 50 and the base station can hold a state in which the terminal device 50 and the base station hold some UE context from each other. The terminal device 50 and the base station can use any held UE context to accelerate the transition of the terminal device 50 to the connected state again. It should be noted that the unconnected state can include the lightning mode. The connected state is, for example, RRC_CONNECTED. RRC_CONNECTED is a connected state in which the terminal device has an established connection to a specific cell (for example, the primary cell), and is also called the CONNECTED mode.

[0226] Figure 11 is a flowchart showing an example of the initial connection processing. In the following, reference will be made to Figure 11An initial connection process is described. The initial connection process described below is executed, for example, in a case where the terminal device 50 is powered on.

[0227] First, the terminal device 50 in the unconnected state implements a cell selection procedure (cell search). The cell selection procedure (cell search) is a procedure that causes a user equipment (UE) to detect a physical cell ID (PCI) of a cell and obtain time and frequency synchronization. The cell search according to the present embodiment includes a step of detecting a synchronization signal and decoding a physical broadcast channel (PBCH). The terminal device 50 detects a synchronization signal of a cell (step S11).

[0228] The terminal device 50 implements synchronization with the cell in the downlink based on the detected synchronization signal. After establishing downlink synchronization, the terminal device 50 attempts to decode the PBCH and acquire a master information block (MIB) that is part of system information (step S12).

[0229] System information is information configured to be broadcast in a cell that transmits the system information. The system information can be common information to all terminal devices 50 belonging to the cell. The system information can be information specific to the cell. The system information includes, for example, information related to cell access, information related to cell selection, information related to other RATs and other systems, and the like. The system information includes an MIB and system information blocks (SIBs). The MIB is information of a fixed size that is necessary for receiving SIBs and the like, and is a payload of the PBCH that is broadcast. The MIB includes a part of a system frame number, information of a subcarrier spacing of predetermined information (e.g., SIB1, Msg. 2 / Msg. 4 for initial connection, paging, and broadcast SI messages), information of a subcarrier offset, information of a location of a DMRS type A, PDCCH configuration for at least SIB1, information of a forbidden cell, information of intra-frequency reselection, and the like. The SIB is system information other than the MIB, and is broadcast by the PDSCH.

[0230] It should be noted that the system information can be classified into first system information, second system information, and third system information. The first system information and the second system information include information related to cell access, information related to acquisition of other system information, and information related to cell selection. The information included in the MIB is the first system information. The information included in SIB1 of the SIB is the second system information (e.g., remaining minimum SI). The remaining system information is the third system information (e.g., other SI).

[0231] In NR, system information is broadcast from an NR cell. A physical channel carrying the system information can be transmitted in a slot or a mini-slot. A mini-slot is defined by less than a symbol of a slot. By transmitting the physical channel carrying the system information in a mini-slot, a time necessary for beam sweeping is shortened, and overhead can be reduced. In the case of NR, first system information is transmitted on an NR-PBCH, and second system information is transmitted on a physical channel different from the NR-PBCH.

[0232] The terminal device 50 acquires the second system information based on the MIB (i.e., the first system information) (step S13). As described above, the second system information includes SIB1 and SIB2.

[0233] SIB1 is access restriction information for a cell and scheduling information of system information other than SIB1. In the case of NR, SIB1 includes information related to cell selection (e.g., cellSelectionInfo), information related to cell access (e.g., cellAccessRelatedInfo), information related to connection establishment failure control (e.g., connEstFailureControl), scheduling information of system information other than SIB1 (e.g., si-SchedulingInfo), configuration of a serving cell, and the like. The configuration of the serving cell includes cell-specific parameters, and includes downlink configuration, uplink configuration, TDD configuration information, and the like. The uplink configuration includes RACH configuration, and the like. In the case of LTE, SIB1 includes cell access information, cell selection information, maximum uplink transmission power information, TDD configuration information, periodicity of system information, mapping information of system information, length of a system information (SI) window, and the like.

[0234] In the case of NR, SIB2 includes cell reselection information (e.g., cellReselectionInfoCommon) and cell reselection serving frequency information (e.g., cellReselectionServingFreqInfo). In the case of LTE, SIB2 includes connection barring information, cell common radio resource configuration information (radioResourceConfigCommon), uplink carrier information, and the like. The cell common radio resource configuration information includes configuration information of a cell common PRACH (Physical Random Access Channel) and RACH (Random Access Channel).

[0235] It should be noted that in a case where the terminal device 50 fails to acquire the system information necessary for establishing a link, the terminal device 50 determines that access to the cell is prohibited. For example, in a case where the first system information fails to be acquired, the terminal device 50 determines that access to the cell is prohibited. At this time, the terminal device 50 ends the initial connection processing.

[0236] In a case where the system information is successfully acquired, the terminal device 50 performs a random access procedure based on the first system information and / or the second system information (step S14). The random access procedure can be referred to as a random access channel (RACH) procedure or a RA procedure.

[0237] The random access procedure includes the following steps: transmitting a random access preamble, receiving a random access response, transmitting a message 3, and receiving a contention resolution.

[0238] First, the terminal device 50 selects a predetermined physical random access channel (PRACH) preamble and transmits the preamble to the non-terrestrial station 30. Subsequently, the terminal device 50 receives a physical downlink shared channel (PDSCH) including a random access response corresponding to the PRACH preamble. Subsequently, the terminal device 50 transmits a PUSCH including a message 3 using resources scheduled by a random access response grant included in the random access response. Finally, the terminal device 50 receives a PDSCH including a contention resolution corresponding to the PUSCH.

[0239] The message 3 includes a radio resource control (RRC) message of an RRC connection request. The contention resolution includes an RRC message of an RRC connection setup. In a case where the RRC message of the RRC connection setup is received, the terminal device 50 implements an RRC connection operation and transitions from an RRC idle state to an RRC connected state. After the transition to the RRC connected state, the terminal device 50 transmits an RRC message of an RRC connection setup complete to the non-terrestrial station 30. This series of operations allows the terminal device 50 to connect to the non-terrestrial station 30.

[0240] It should be noted that the random access preamble can be referred to as a message 1, the random access response can be referred to as a message 2, the contention resolution can be referred to as a message 4, and the RRC connection setup complete message can be referred to as a message 5.

[0241] After all steps of the random access procedure are completed, the terminal device 50 can transition to a state connected to the cell (connected state).

[0242] It should be noted that the random access procedure described above can be referred to as a 4-step random access procedure (4-step RACH procedure). On the other hand, a 2-step random access procedure (2-step RACH procedure) can refer to a random access procedure in which the terminal device 50 transmits a message 3 along with the transmission of a random access preamble, and in response, the non-terrestrial station 30 transmits a random access response and a contention resolution.

[0243] The random access procedure will be described in detail hereinafter.

[0244] 3-2. Random Access Procedure

[0245] The random access procedure is performed for the purpose of "RRC connection setup" from the idle state to the connected state (or inactive state), "state transition request" for state transition from the inactive state to the connected state, and the like. The random access procedure is also used for the purpose of "scheduling request" for requesting resources for uplink data transmission and "timing advance adjustment" for adjusting uplink synchronization. Furthermore, the random access procedure is performed in the case of "on-demand SI request" for requesting system information that is not transmitted, "beam recovery" for recovering a broken beam connection, "handover" for switching a connected cell, and the like.

[0246] "RRC connection setup" is an operation performed when the terminal device 50 connects to the non-terrestrial station 30 in response to the occurrence of traffic or the like. Specifically, the connection operation is an operation of transferring information related to the connection (for example, UE context) from the non-terrestrial station 30 to the terminal device 50. The UE context is managed by predetermined communication device identification information (for example, C-RNTI) indicated by the non-terrestrial station 30. Upon completion of the operation, the terminal device 50 implements state transition from the idle state to the inactive state or from the idle state to the connected state.

[0247] "State transition request" is an operation in which the terminal device 50 requests state transition from the inactive state to the connected state in response to the occurrence of traffic or the like. By transitioning to the connected state, the terminal device 50 can transmit and receive unicast data to / from the non-terrestrial station 30.

[0248] "Scheduling request" is an operation in which the terminal device 50 implements a request for resources for uplink data transmission in response to the occurrence of traffic or the like. After the non-terrestrial station 30 successfully receives the scheduling request, the non-terrestrial station 30 assigns resources for PUSCH to the communication device. It should be noted that the scheduling request is also implemented by PUCCH.

[0249] "Timing advance adjustment" is an operation for adjusting an error between downlink frames and uplink frames caused by a propagation delay. The terminal device 50 transmits a physical random access channel (PRACH) at a timing adjusted to a downlink frame. Accordingly, the non-terrestrial station 30 can recognize a propagation delay from the terminal device 50, and can indicate a value of the timing advance to the terminal device 50 through a message 2 or the like.

[0250] "SI request on demand" is an operation in which, in a case where the terminal device 50 requires system information, the non-terrestrial station 30 is requested to transmit system information that is not transmitted for the purpose of overhead of the system information or the like.

[0251] "Beam recovery" is an operation in which, after a beam is established, a return request is implemented in a case where a communication quality is degraded due to a movement of the terminal device 50, a communication path is blocked by another object, or the like. Upon receipt of the request, the non-terrestrial station 30 attempts to connect to the terminal device 50 using a different beam.

[0252] "Handover" is an operation in which, due to a change in a radio wave environment such as a movement of the terminal device 50 or the like, a connection is switched from a cell (a serving cell) to which the terminal device 50 is connected to a cell (a neighbor cell) adjacent to the serving cell. Upon receipt of a handover command from the non-terrestrial station 30, the terminal device 50 implements a connection request to the neighbor cell designated by the handover command.

[0253] The random access procedure includes a contention-based random access procedure and a non-contention-based random access procedure.

[0254] It should be noted that the random access procedure described below is a random access procedure assuming that the RAT supported by the communication system 1 is LTE. However, the random access procedure described below is also applicable to a random access procedure assuming that the RAT supported by the communication system 1 is other than LTE. For example, the random access procedure described below is also applicable to a case where the RAT supported by the communication system 1 is 6G.

[0255] The contention-based random access procedure and the non-contention-based random access procedure will be described in detail hereinafter.

[0256] 3-2-1. Contention-based random access procedure

[0257] The contention-based random access procedure is a random access procedure implemented at the initiative of the terminal device 50. Figure 12 is a diagram illustrating the contention-based random access procedure. As Figure 12As shown in FIG. 1, the contention-based random access procedure is a 4-step procedure that starts with the terminal device 50 sending a random access preamble. The contention-based random access procedure includes the following steps: sending a random access preamble (message 1), receiving a random access response (message 2), sending a message (message 3), and receiving a contention resolution message (message 4).

[0258] First, the terminal device 50 randomly selects a check-in code sequence to be used from among a predetermined plurality of preamble sequences. Subsequently, the terminal device 50 sends a message including the selected check-in code sequence to the connected non-terrestrial station 30 (message 1: random access preamble) (step S21). The random access preamble is sent on the PRACH.

[0259] Upon receiving the random access preamble, the non-terrestrial station 30 sends a corresponding random access response (message 2: random access response) to the terminal device 50. The random access response is sent, for example, using the PDSCH. The terminal device 50 receives the random access response (message 2) sent from the non-terrestrial station 30 (step S22). The random access response includes one or more random access preambles that were successfully received by the non-terrestrial station 30 and uplink (UL) resources (hereinafter referred to as uplink grant) corresponding to the random access preambles. The random access response also includes a temporary cell radio network temporary identifier (TC-RNTI), which is an identifier that is temporarily assigned to the terminal device 50 by the non-terrestrial station 30 and is unique to the terminal device 50.

[0260] Upon receiving the random access response from the non-terrestrial station 30, the terminal device 50 determines whether the received information includes the random access preamble sent in step S21. In the case where the received information includes the random access preamble, the terminal device 50 extracts the uplink grant corresponding to the random access preamble sent in step S21 from among the uplink grants included in the random access response. Subsequently, the terminal device 50 sends an UL message (message 3: scheduled transmission) using the resources scheduled by the extracted uplink grant (step S23). The sending of the message (message 3) is implemented using the PUSCH. The message (message 3) includes a radio resource control (RRC) message for an RRC connection request. The message (message 3) also includes an identifier of the terminal device 50.

[0261] In the contention-based random access procedure, the random access preamble randomly selected by the terminal device 50 is used for the procedure. Accordingly, it is possible that, at the same time as the terminal device 50 transmits the random access preamble, another terminal device 50 transmits the same random access preamble to the non-terrestrial station 30. Therefore, by receiving the identifier transmitted by the terminal device 50 in step S23, the non-terrestrial station 30 identifies between which terminal devices the contention of the preamble has occurred, and implements contention resolution. The non-terrestrial station 30 transmits the contention resolution (message 4: contention resolution) to the terminal device 50 selected by the contention resolution. The contention resolution (message 4) includes the identifier transmitted by the terminal device 50 in step S23. The contention resolution (message 4) includes an RRC message of RRC connection setup. The terminal device 50 receives the contention resolution message (message 4) transmitted from the non-terrestrial station 30 (step S24).

[0262] The terminal device 50 compares the identifier transmitted in step S23 with the identifier received in step S24. In the case where the identifiers do not match, the terminal device 50 implements the random access procedure again from step S21. In the case where the identifiers match, the terminal device 50 implements an RRC connection operation, and transitions from the idle state (RRC IDLE) to the connected state (RRC CONNECTED). The terminal device 50 uses the TC-RNTI acquired in step S22 as a cell radio network temporary identifier (C-RNTI) in subsequent communication. After the transition to the connected state, the terminal device 50 transmits an RRC message of RRC connection setup complete to the non-terrestrial station 30. The RRC connection setup complete message is also referred to as message 5. Through this series of operations, the terminal device 50 connects to the non-terrestrial station 30.

[0263] It should be noted that, Figure 12 The contention-based random access procedure illustrated in FIG. 6 is a 4-step random access procedure (4-step RACH). However, as the contention-based random access procedure, the communication system 1 can also support a 2-step random access procedure (2-step RACH). For example, the terminal device 50 transmits the message (message 3) indicated in step S23 together with the random access preamble. Subsequently, in response to the random access preamble and the message 3, the non-terrestrial station 30 transmits a random access response (message 2) and a contention resolution (message 4). Since the random access procedure is completed in two steps, the terminal device 50 can quickly connect to the non-terrestrial station 30.

[0264] It should be noted that message 1 can be denoted as "Msg1" or "Msg. 1". Message 2 can be denoted as "Msg2" or "Msg. 2". Message 3 can be denoted as "Msg3" or "Msg. 3". Message 4 can be denoted as "Msg4" or "Msg. 4".

[0265] 3-2-2. Contention-free random access procedure

[0266] The contention-free random access procedure is a random access procedure that is implemented at the initiative of the non-terrestrial station 30. Figure 13 is a diagram illustrating a contention-free random access procedure. The contention-free random access procedure is a 3-step procedure that starts with sending a random access preamble assignment from the non-terrestrial station 30. The contention-free random access procedure includes the following steps: receiving a random access preamble assignment (message 0), sending a random access preamble (message 1), and receiving a random access response (message 2).

[0267] In the contention-based random access procedure, the terminal device 50 randomly selects a preamble sequence. But in the contention-free random access procedure, the non-terrestrial station 30 assigns a separate random access preamble to the terminal device 50. The terminal device 50 receives the assignment of the random access preamble from the non-terrestrial station 30 (message 0: RA preamble assignment) (step S31).

[0268] The terminal device 50 performs random access to the non-terrestrial station 30 using the random access preamble assigned in step S31. That is, the terminal device 50 sends the assigned random access preamble to the non-terrestrial station 30 on the PRACH (message 1: random access preamble) (step S32).

[0269] The non-terrestrial station 30 receives the random access preamble from the terminal device 50 (message 1). Subsequently, the non-terrestrial station 30 sends a random access response for the random access preamble to the terminal device 50 (message 2) (step S33). The random access response includes, for example, information of an uplink grant corresponding to the received random access preamble. Upon receiving the random access response (message 2), the terminal device 50 implements an RRC connection operation and transitions from the idle state (RRC_IDLE) to the connected state (RRC_CONNECTED).

[0270] Thus, in the contention-free random access procedure, the non-terrestrial station 30 schedules the random access preamble, so that preamble collision is less likely to occur.

[0271] Message 0 can be denoted as "Msg0" or "Msg. 0". Message 1 can be denoted as "Msg1" or "Msg. 1". Message 2 can be denoted as "Msg2" or "Msg. 2".

[0272] 3-3. Details of random access procedure of NR

[0273] The preceding description assumes that the RAT supported by communication system 1 is LTE-based random access procedure. It should be noted that the random access procedure described above also applies to RATs other than LTE. The following section will describe in detail the random access procedure for NR-based RATs supported by communication system 1.

[0274] It should be noted that the following description will describe the relationship with... Figure 12 or Figure 13 The diagram shows the four steps related to messages 1 through 4. The steps in message 1 correspond to... Figure 12 Step S21 and shown Figure 13 The step S32 shown in the image. Step 2 in message 2 corresponds to... Figure 12 Step S22 and shown Figure 13 The step S33 shown in the image. Step 3 in message 3 corresponds to... Figure 12 The step S23 shown in the image. Step 4 corresponds to... Figure 12 Step S24 is shown in the figure.

[0275] NR's random access preamble (message 1)

[0276] In NR, PRACH is called the NR Physical Random Access Channel (NR-PRACH). The Zadoff-Chu sequence is used to configure NR-PRACH. In NR, multiple preamble formats are defined as the format of NR-PRACH. The preamble format is defined by a combination of parameters such as the PRACH subcarrier spacing, transmission bandwidth, sequence length, number of symbols used for transmission, number of transmission repetitions, cyclic prefix (CP) length, and guard period length. The types of NR-PRACH preamble sequences are numbered. The numbering of the preamble sequence types is called the preamble index.

[0277] In NR, system information is used to provide NR-PRACH-related configuration for terminal device 50 in an idle state. Additionally, dedicated RRC signaling is used to configure NR-PRACH-related settings for terminal device 50 in a connected state.

[0278] Terminal device 50 transmits NR-PRACH using physical resources (NR-PRACH timing) that allow NR-PRACH transmission. Physical resources are indicated through configuration associated with NR-PRACH. Terminal device 50 selects any physical resource and uses it to transmit NR-PRACH. Furthermore, when terminal device 50 is in a connected state, it transmits NR-PRACH using NR-PRACH resources. NR-PRACH resources are a combination of the NR-PRACH preamble and its physical resources. Non-ground station 30 can indicate NR-PRACH resources to terminal device 50.

[0279] It should be noted that the NR-PRACH is also transmitted when the random access procedure fails. When retransmitting the NR-PRACH, the terminal device 50 waits for transmission of the NR-PRACH for a waiting period calculated from a value of backoff (backoff indicator BI). It should be noted that the value of backoff can differ depending on the terminal category of the terminal device 50 or the priority of the generated traffic. At this time, a plurality of values of backoff are provided as notification, and the terminal device 50 selects the value of backoff to be used depending on the priority. When retransmitting the NR-PRACH, the terminal device 50 increases the transmission power of the NR-PRACH compared to the transmission power in the initial transmission. This procedure is called power ramping.

[0280] Random access response (message 2) of NR

[0281] The random access response of NR is transmitted using the NR physical downlink shared channel (NR-PDSCH). The NR-PDSCH including the random access response is scheduled by the NR physical downlink control channel (NR-PDCCH) in which the cyclic redundancy check (CRC) is scrambled with the RA-RNTI. The NR-PDCCH in which the CRC is scrambled with the RA-RNTI is allocated in the common search space (CSS) of the first type PDCCH CSS set. It should be noted that the value of the random access radio network temporary identifier (RA-RNTI) is determined based on the transmission resource for the NR-PRACH corresponding to the random access response. The transmission resource for the NR-PRACH includes, for example, the time resource (slot or subframe) and the frequency resource (resource block). It should be noted that the NR-PDCCH can be allocated in the associated search space of the NR-PRACH associated with the random access response. Specifically, the search space in which the NR-PDCCH is allocated is configured in association with the preamble of the NR-PRACH and / or the physical resource in which the NR-PRACH is transmitted. The search space in which the NR-PDCCH is allocated is configured in association with the index of the preamble and / or the index of the physical resource. The NR-PDCCH has a quasi co-location (QCL) relationship with the NR synchronization signal (NR-SS).

[0282] The random access response of NR is medium access control (MAC) information. The random access response of NR includes at least the uplink grant for transmitting the message 3 of NR, the value used for adjusting the timing advance of the uplink frame synchronization, and the value of the TC-RNTI. The random access response of NR also includes the PRACH index used for the NR-PRACH transmission corresponding to the random access response. The random access response of NR also includes information related to the backoff used for waiting for the transmission of the PRACH.

[0283] The non-terrestrial station 30 transmits a random access response on the NR-PDSCH. The terminal device 50 determines from the information included in the random access response whether the transmission of the random access preamble was successful. In the case where it is determined that the transmission of the random access preamble was successful, the terminal device 50 implements the processing of transmitting the message 3 of the NR in accordance with the information included in the random access response. On the other hand, in the case where the transmission of the random access preamble failed, the terminal device 50 determines that the random access procedure has failed and implements a retransmission processing for the NR-PRACH.

[0284] It should be noted that the random access response of the NR can include a plurality of uplink grants for transmitting the message 3 of the NR. The terminal device 50 can select one resource from among the plurality of uplink grants for transmitting the message 3 (message 3). Accordingly, in the case where different terminal devices 50 receive the same NR random access response, the contention between the transmissions of the message 3 of the NR can be alleviated. As a result, the communication system 1 can provide a more stable random access procedure.

[0285] Message 3 of the NR

[0286] The message 3 of the NR is transmitted through the NR physical uplink shared channel (NR-PUSCH). The NR-PUSCH is transmitted using the resource indicated through the random access response. The message 3 of the NR includes an RRC connection request message. The format of the NR-PUSCH is indicated through a parameter included in the system information. For example, the parameter determines which one of the orthogonal frequency division multiplexing (OFDM) and the discrete Fourier transform spread OFDM (DFT-s-OFDM) is used as the format of the NR-PUSCH.

[0287] In the case where the message 3 of the NR is normally received, the non-terrestrial station 30 transitions to the transmission processing of the contention resolution (message 4). On the other hand, in the case where the message 3 of the NR is not normally received, the non-terrestrial station 30 again attempts to receive the message 3 of the NR for at least a predetermined period.

[0288] Another example of the retransmission of the message 3 and the indication of the transmission resource thereof is the indication through the NR-PDCCH used for the message 3 retransmission indication. The NR-PDCCH is an uplink grant. The downlink control information (DCI) of the NR-PDCCH indicates the resource for the message 3 retransmission. The terminal device 50 retransmits the message 3 based on the indication of the uplink grant.

[0289] It should be noted that if the NR contention resolution is not successfully received within a predetermined period, the terminal device 50 considers that the random access procedure has failed and implements the NR-PRACH retransmission process. It should be noted that the transmission beam of the terminal device 50 used for the message 3 retransmission for NR can be different from the transmission beam of the terminal device 50 used for the initial transmission of the message 3. It should be noted that in the case where neither the contention resolution for NR nor the message 3 retransmission indication is received within a predetermined period, the terminal device 50 considers that the random access procedure has failed and implements the retransmission process for the NR-PRACH. The predetermined period is configured, for example, by system information.

[0290] Contention resolution (message 4) for NR

[0291] The contention resolution for NR is transmitted using the NR-PDSCH. The NR-PDSCH including the contention resolution is scheduled by the NR-PDCCH in which the CRC is scrambled with the TC-RNTI or the C-RNTI. The NR-PDCCH in which the CRC is scrambled with the TC-RNTI is allocated in the CSS of the first type PDCCH CSS set. It should be noted that the NR-PDCCH can be allocated in the user equipment specific search space (USS). It should be noted that the NR-PDCCH can be allocated in another CSS.

[0292] In the case where the NR-PDSCH including the contention resolution is normally received, the terminal device 50 transmits an acknowledgement (ACK) to the non-terrestrial station 30. Subsequently, the terminal device 50 considers that the random access procedure has succeeded and transitions to the connected state (RRC_CONNECTED). On the other hand, in the case where a negative acknowledgement (NACK) for the NR-PDSCH is received from the terminal device 50, or in the case where no response is received, the non-terrestrial station 30 retransmits the NR-PDSCH including the contention resolution. If the contention resolution for NR (message 4) is not successfully received within a predetermined period, the terminal device 50 considers that the random access procedure has failed and implements the process of retransmitting the random access preamble (message 1).

[0293] 3-4, 2-step RACH for NR

[0294] An example of the 2-step RACH procedure for NR (hereinafter referred to as the 2-step random access procedure) will now be described. Figure 14is a diagram illustrating a 2-step random access procedure. The 2-step random access procedure is configured with two steps, a message A (step S41) and a message B (step S42). As an example, the message A includes a preamble and a PUSCH of a known 4-step random access procedure (4-step RACH procedure), and the message B includes a PDSCH of the known 4-step random access procedure. As an example, the message A includes a preamble (also referred to as PRACH) and a PUSCH, and the message B includes a PDSCH.

[0295] The 2-step random access procedure allows to complete the random access procedure with lower latency than the 4-step random access procedure.

[0296] The preamble and the PUSCH included in the message A can be configured with transmission resources for the preamble and the PUSCH associated with each other, or can be configured with independent resources.

[0297] In a case where the transmission resources are configured associated with each other, for example, in a case where the transmission resources for the preamble are determined, the transmission resources for the PUSCH are uniquely determined, or the transmission resources for the PUSCH which can be multiple candidates are determined. For example, a time and frequency offset between the preamble of the PRACH occasion and the PUSCH occasion can be defined by one value. As another example, the time and frequency offset between the preamble of the PRACH occasion and the PUSCH occasion is defined by different values for each preamble. The value of the offset can be determined by a specification or can be configured by the non-terrestrial station 30 in a quasi-static manner. As an example of the value of the time and frequency offset, the value is defined by a predetermined frequency, for example. For example, in an unlicensed band (e.g., 5 GHz band, band 45), the value of the time offset can be configured to 0 or a value approximately equal to 0. This allows to omit listen before talk (LBT) before the transmission of the PUSCH.

[0298] On the other hand, in a case where the preamble and the PUSCH are configured with independent resources, the transmission resources for the preamble and the PUSCH can be determined in a specification, the resources can be configured by the non-terrestrial station 30 in a quasi-static manner, or the resources can be determined from other information. Examples of the other information include slot format information (e.g., slot format indicator, etc.), BWP (bandwidth part) information, preamble transmission resource information, slot index, resource block index, etc. In a case where the preamble and the PUSCH included in one message A are configured with independent resources, the management between the preamble and the PUSCH can be provided as a notification to the base station by the payload of the PUSCH or the UCI included in the PUSCH, or can be provided as a notification to the non-terrestrial station 30 by the transmission physical parameters of the PUSCH (e.g., scrambling sequence, DMRS sequence and / or pattern of the PUSCH, or transmission antenna port of the PUSCH).

[0299] The configuration method of the transmission resource for the preamble and the PUSCH can be switched between the case where the transmission resources are configured in association with each other and the case where independent resources are configured for the transmission resources. For example, the case where independent resources are configured for the transmission resources can be applied in a licensed band, and the case where the transmission resources are configured in association with each other can be applied in an unlicensed band.

[0300] The random access procedure described above assumes that the RAT supported by the communication system 1 is NR. It should be noted that the random access procedure described above is also applicable to RATs other than LTE (for example, 6G).

[0301] 4. Operation of the communication system

[0302] The basic operation of the communication system 1 described above, the operation of the communication system 1 that can solve the problem of the present embodiment will be described next.

[0303] In the following description, specific values are indicated in some specific examples, but the values are not limited to the examples, and other values can be used.

[0304] In the following description, a resource means a frequency, a time, a resource unit (including an REG, a CCE, and a CORESET), a resource block, a bandwidth part, a component carrier, a symbol, a sub-symbol, a slot, a mini-slot, a sub-slot, a subframe, a frame, a PRACH occasion, an occasion, a code, a multiple access physical resource, a multiple access signature, a subcarrier spacing (numerology), and the like.

[0305] The following description contains statements that do not implement handover, and not implementing handover indicates, for example, not transmitting a handover command and not implementing a random access procedure.

[0306] In the following description, a "communication area" formed by a non-terrestrial station 30 (for example, a non-geostationary satellite station) can be referred to as a "cell-formed area". The term "cell-formed area" in the following description can be replaced with "communication area".

[0307] In the following description, "switching of connection" (for example, switching of connection from a first non-geostationary satellite station to a second non-geostationary satellite station) can be referred to as "switching of cell-formed area". The statement "information related to switching of cell-formed area" in the following description can be replaced with "information related to switching of connection".

[0308] In the following description, "information related to switching of connection" can be referred to as "information related to switching of cell-formed area". The statement "information related to switching of cell-formed area" in the following description can be replaced with "information related to switching of connection".

[0309] In the following description, the non-terrestrial station 30 is a non-geostationary satellite station, but the non-terrestrial station 30 is not limited to the non-geostationary satellite station. For example, the non-terrestrial station 30 can be an aircraft station. In the following description, the term "non-geostationary satellite station" appearing in the following description can be replaced with "aircraft station" or "non-terrestrial station".

[0310] 4-1, Overview of the process

[0311] An overview of the process of the communication system 1 will be described.

[0312] The communication system 1 of the present embodiment includes a base station and a terminal device 50. The base station can be a non-terrestrial station 30 or a terrestrial station 20. In the present embodiment, a plurality of non-geostationary satellite stations form a satellite constellation. The base station of the present embodiment can be a non-terrestrial station 30 connected to the terminal device 50 as one of the plurality of non-geostationary satellite stations, or can be a terrestrial station 20 connected to the terminal device 50 in a case where one of the plurality of non-geostationary satellite stations serves as a relay station.

[0313] As described with reference to Figure 1 In the present embodiment, each of the plurality of non-geostationary satellite stations forms a communication area (hereinafter also referred to as a cell formation area) on the ground at a predetermined cell position. As described earlier, as the non-geostationary satellite station moves, the terminal device 50 needs to hand over the connection from a first non-geostationary satellite station to a second non-geostationary satellite station. Here, the first non-geostationary satellite station and the second non-geostationary satellite station are each one of the plurality of non-geostationary satellite stations forming the satellite constellation.

[0314] Before the terminal device hands over the connection from the first non-geostationary satellite station to the second non-geostationary satellite station, the base station notifies the terminal device 50 in advance of information related to the handover of the connection from the first non-geostationary satellite station to the second non-geostationary satellite station (information related to the handover of the cell formation area).

[0315] Before the process of switching from the first non-geostationary satellite station to the second non-geostationary satellite station, the terminal device 50 acquires in advance from the first non-geostationary satellite station information related to the handover of the connection. Subsequently, the terminal device 50 hands over the connection from the first non-geostationary satellite station to the second non-geostationary satellite station without handover (that is, without performing a random access procedure) based on the information related to the handover of the connection.

[0316] Having described an overview of the process of the communication system 1, the operation of the communication system 1 will be described in detail.

[0317] 4-2, Notification of information related to handover of cell formation area

[0318] First, the notification of information related to the handover of the cell formation area will be described.

[0319] The base station dynamically or quasi-statically notifies the terminal device 50 of the information related to the handover of the cell formation area in advance, that is, before the handover of the cell formation area. The dynamic notification can be a notification by downlink control information (DCI) or a MAC control element (MAC CE). The quasi-static notification can be a notification by system information or RRC signaling.

[0320] Specific examples of the information related to the handover of the cell formation area

[0321] The information related to the handover of the cell formation area (the information related to the handover of the connection) can include, for example, the following information (A) to (C). The information related to the handover of the cell formation area can include a part of the information indicated below, or can include all the information indicated below. Of course, the information related to the handover of the cell formation area can include information other than the information described below.

[0322] (A) Information related to the handover processing for the cell formation area

[0323] The information related to the handover of the cell formation area can include information related to the processing of the handover of the cell formation area. The information related to the processing of the handover of the cell formation area is information used by the terminal device 50 for the processing of the handover of the connection. The information related to the processing of the handover of the cell formation area can be, for example, any one of the following (A1) to (A4).

[0324] (A1) Information related to the execution of the handover of the cell formation area

[0325] As the information related to the handover of the cell formation area, the base station can transmit information related to the execution of the handover of the cell formation area. The information related to the execution of the handover of the cell formation area is information for the terminal device 50 side to determine whether to implement the handover of the cell formation area.

[0326] The terminal device 50 that receives this information determines to handover the cell formation area at a predetermined timing. For example, in a case where the information related to the handover of the cell formation area includes the information related to the execution of the handover of the cell formation area, the terminal device 50 starts the processing of the handover of the connection from the first non-geostationary satellite station to the second non-geostationary satellite station at a predetermined timing after the reception of the information related to the handover of the cell formation area.

[0327] Here, the predetermined timing can be a timing at which the terminal device 50 receives the information (information related to execution of switching of the cell-formed area), or can be a timing at which a predetermined time elapses since the terminal device 50 receives the information. Here, the predetermined time can be a time determined on the basis of timer information or the like provided as notification in advance. The predetermined time can also be a time determined on the basis of information of a time offset. The predetermined time can also be a time determined on the basis of information related to a trigger for switching of the cell-formed area, which will be described later.

[0328] For execution of switching of the cell-formed area, the base station can implement notification of the information (information related to execution of switching of the cell-formed area) using control information such as group common downlink control information (DCI) or the like. For example, for execution of switching of the cell-formed area, the base station can implement notification of a group common radio network temporary identifier (RNTI). The terminal device 50 can use the information to decode the group common downlink control information (DCI).

[0329] (A2) Information related to a trigger for switching of the cell-formed area

[0330] As the information related to switching of the cell-formed area, the base station can transmit information related to a trigger for implementing switching of the cell-formed area (hereinafter also referred to as trigger information). Upon receiving the information, the terminal device 50 can implement switching of the cell-formed area using the trigger for switching of the cell-formed area. For example, the terminal device 50 can start a process of switching a connection from the first non-geostationary satellite station to the second non-geostationary satellite station at a timing determined on the basis of the trigger information provided as notification.

[0331] The trigger information can include the information indicated in (1) to (5) below.

[0332] (1) Timer information related to switching of the cell-formed area

[0333] The trigger information can include timer information related to switching of the cell-formed area. At this time, the terminal device 50 can start a switching process at a timing determined by the timer information.

[0334] (2) Information related to a start time of switching of the cell-formed area

[0335] The trigger information can include information related to a start time of switching of the cell-formed area. At this time, the terminal device 50 can start a switching process in a case where the start time determined on the basis of the information comes.

[0336] (3) Information related to a start time of a trigger detection operation related to switching of a cell-formed area

[0337] The trigger information can include information related to an execution start time of a trigger detection operation related to switching of a cell-formed area. At this time, the terminal device 50 can start the trigger detection operation in a case where the start time comes based on the information.

[0338] (4) Information for determining a positional relationship of the non-geostationary satellite station and / or the terminal device 50

[0339] The trigger information can include information for determining a position of the non-geostationary satellite station, such as position information, time information, orbit information, altitude information, and time information necessary for the non-geostationary satellite station to encircle the Earth. The trigger information can also include position information, moving speed information, and moving direction information of the terminal device 50.

[0340] Further, the trigger information can include position information of the non-geostationary satellite station and / or position information of the terminal device 50, which is considered as a trigger occurrence. For example, the trigger information can include position information of at least one of the first non-geostationary satellite station, the second non-geostationary satellite station, or the terminal device 50. Subsequently, in a case where the position of at least one of the first non-geostationary satellite station, the second non-geostationary satellite station, or the terminal device coincides with a position indicated by the position information, the terminal device 50 can start the switching process.

[0341] (5) Information related to communication quality

[0342] The trigger information can include information related to communication quality. For example, the trigger information can include the following information.

[0343] - Information related to reception quality (Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), etc.)

[0344] - Information related to a threshold (Threshold) of communication quality (e.g., RSRP)

[0345] - Information related to an offset amount of communication quality (e.g., RSRP)

[0346] (A3) Information related to a switching destination or a switching order of a cell-formed area

[0347] As the information related to the switching of the cell-formed area, the base station can transmit information related to the switching destination of the cell-formed area or the switching order (the order of application of the information related to the cell-formed area). For example, the base station can uniformly notify the terminal device 50 of the switching destination of the cell-formed area. In this case, the terminal device 50 can determine the order of switching the cell-formed area using the information.

[0348] (A4) Information related to the communication operation during the switching of the cell-formed area

[0349] As the information related to the switching of the cell-formed area, the base station can transmit information related to the communication operation of the base station and / or the terminal device during the switching of the cell-formed area. For example, the base station can transmit information related to whether transmission and reception are stopped during the switching of the cell-formed area or the period of time during which transmission and reception are stopped. For example, it is assumed that the base station and the terminal device 50 cannot transmit and receive data during the period of time in which the cell-formed area is switched. At this time, the base station notifies the terminal device 50 in advance of the operation during the switching of the cell-formed area, thereby preventing communication errors. For example, the base station notifies the terminal device 50 in advance of information indicating whether data can be transmitted during the switching of the cell-formed area. The base station also notifies the terminal device 50 in advance of information indicating a data transmission / reception prohibition period provided for the switching of the cell-formed area.

[0350] (B) Information related to the communication parameter after the switching of the cell-formed area

[0351] The information related to the switching of the cell-formed area can include information related to the communication parameter after the switching of the cell-formed area (hereinafter simply referred to as communication parameter information). The communication parameter information is information related to the transmission parameter and / or the reception parameter used by the terminal device 50 after the switching of the cell-formed area.

[0352] The terminal device 50 can switch the communication parameter (the transmission parameter and / or the reception parameter) after the switching of the cell-formed area and perform communication. When the terminal device 50 configures the communication parameter to be a parameter suitable for the base station (satellite station) to perform communication after the switching of the cell-formed area, it is expected that the communication quality will be improved.

[0353] The communication parameter information can include the information indicated in (1) to (10) below.

[0354] (1) Information related to the terminal-specific timing advance and / or the cell-common timing advance after the switching of the cell-formed area

[0355] (2) Information related to the transmission timing (frame) synchronization after the switching of the cell-formed area

[0356] (3) Terminal-unique ID after the handover of the cell-forming area (Cell-Radio Network Temporary Identifier (C-RNTI))

[0357] (4) Information related to the frequency band after the handover of the cell-forming area

[0358] (5) Synchronization signal / PBCH block index (SSB index) after the handover of the cell-forming area

[0359] (6) Information related to the transmission weight after the handover of the cell-forming area

[0360] (7) Information related to the number of times of repeated transmission after the handover of the cell-forming area

[0361] (8) Information related to the Hybrid Automatic Repeat Request disable (HARQ disable) after the handover of the cell-forming area

[0362] (9) Information related to the transmission power after the handover of the cell-forming area

[0363] (10) Information related to the position, orbit, time, and altitude of the satellite device after the handover of the cell-forming area

[0364] (C) Information related to the random access procedure after the handover of the cell-forming area

[0365] The information related to the handover of the cell-forming area can include information related to the random access procedure after the handover of the cell-forming area. For example, the information related to the handover of the cell-forming area can include information necessary for the random access procedure after the handover of the cell-forming area.

[0366] (C1) Information necessary for the random access procedure

[0367] As the information related to the handover of the cell-forming area, the base station can transmit information necessary for the random access procedure after the handover of the cell-forming area. Upon the handover of the cell-forming area, the terminal device 50 basically implements the handover (i.e., the random access procedure) without performing the handoff. However, when the cell-forming area is handed over without performing the random access procedure, it is assumed that the terminal device 50 can not be able to normally communicate with the second non-geostationary satellite station (or the second base station using the second non-geostationary satellite station as a relay station) after the handover of the cell-forming area. At this time, the terminal device 50 falls back to the random access procedure, and implements the connection procedure with the second non-geostationary satellite station (or the second base station using the second non-geostationary satellite station as a relay station). The base station can previously notify the terminal device 50 of information necessary for the procedure.

[0368] Information necessary for the random access procedure after the handover of the cell-formed area can include information indicated in (1) to (6) below.

[0369] (1) Resource for physical random access channel (PRACH) transmission after the handover of the cell-formed area

[0370] (2) Preamble sequence after the handover of the cell-formed area

[0371] (3) Cell ID after the handover of the cell-formed area

[0372] (4) Uplink / downlink carrier frequency after the handover of the cell-formed area

[0373] (5) Bandwidth after the handover of the cell-formed area

[0374] (6) Radio resource configuration after the handover of the cell-formed area

[0375] (C2) Information related to necessity / unnecessity of the random access procedure

[0376] As the information related to the handover of the cell-formed area, the base station can receive information related to whether the random access procedure is necessary after the handover of the cell-formed area (or at the time of the process of handover of the cell-formed area). The information related to whether the random access procedure is necessary (also referred to as information related to skipping of the random access procedure) is information for determining whether the random access procedure is necessary for the handover of the cell-formed area. In a case where it is determined based on the information described above that the random access procedure is unnecessary, the terminal device 50 skips the random access procedure at the time of the handover of the cell-formed area. That is, the terminal device 50 handovers the cell-formed area without performing the random access procedure. On the other hand, in a case where it is determined that the random access procedure is necessary, the terminal device 50 performs the random access procedure at the time of the handover of the cell-formed area.

[0377] Others

[0378] The information related to the handover of the cell-formed area can be notified from the connected base station to the terminal device 50 before the handover of the cell-formed area, or the information can be notified to the terminal device 50 at the time of the cell attachment.

[0379] There can be one or more pieces of information related to the handover of the cell formation area. For example, assume that the base station is a non-terrestrial station 30 such as a satellite station moving on a predetermined orbit. Alternatively, assume that the base station is an apparatus using a non-terrestrial station 30 moving on a predetermined orbit as a relay station. At this time, the base station and / or the terminal apparatus 50 can estimate a non-terrestrial station 30 (e.g., a satellite station) to which the terminal apparatus 50 can connect in the future. Accordingly, the base station notifies the terminal apparatus 50 in advance of a plurality of pieces of information related to the handover of the cell formation area. The terminal apparatus 50 uses the notified plurality of pieces of information to implement processing at the time of the handover of the cell formation area.

[0380] It should be noted that, in the case where the base station notifies the terminal apparatus 50 of a plurality of pieces of information related to the handover of the cell formation area, the base station can add information related to the order of application of the information related to the handover of the cell formation area to the information related to the handover of the cell formation area. The terminal apparatus 50 can apply the information related to the handover of the cell formation area in the order indicated by the information related to the order.

[0381] 4-3. Implementation of the Handover of the Cell Formation Area

[0382] The handover of the cell formation area by the terminal apparatus 50 will now be described.

[0383] Upon receiving the information related to the handover of the cell formation area, the terminal apparatus 50 implements the handover of the cell formation area on the basis of the received information.

[0384] Handover Example 1

[0385] As described earlier, the information related to the handover of the cell formation area can include information related to the execution of the handover of the cell formation area. The terminal apparatus 50 can implement the handover of the cell formation area upon receiving the information related to the handover of the cell formation area. At this time, the terminal apparatus 50 can implement the handover of the cell formation area at the timing of receiving the information related to the execution of the handover of the cell formation area. Alternatively, the terminal apparatus 50 can implement the handover of the cell formation area at the timing of elapse of a predetermined time from the reception of the information related to the execution of the handover of the cell formation area. The predetermined time can be a time uniquely determined by a specification or the like, or can be a time provided as notification by control information or the like.

[0386] Handover Example 2

[0387] As described above, the information related to the handover of the cell forming area can include information related to a trigger for implementing the handover of the cell forming area (hereinafter referred to as trigger information). The terminal device 50 can hand over the cell forming area based on the trigger information. For example, the terminal device 50 can determine to implement the handover of the cell forming area when any one of the following triggers (1) to (3) is satisfied. The following trigger examples are merely illustrative and are not limiting.

[0388] (1) When a timer related to the handover of the cell forming area becomes zero

[0389] (2) When a start time of the handover of the cell forming area arrives

[0390] (3) In a case where a position of a satellite station considered to be a trigger occurrence and / or a position of the terminal device is provided in advance as a notification.

[0391] It should be noted that the position of the satellite station considered to be the trigger occurrence in (3) can be a position determined from position information of the non-geostationary satellite, time information, orbit information, altitude information, time information necessary for orbiting the earth, and the like.

[0392] The terminal device 50 can apply any one of the following (4) to (10) as a trigger. The following trigger examples are merely illustrative and are not limiting.

[0393] (4) In a case where a communication quality (for example, RSRP) of a cell forming area to which the terminal device 50 belongs is equal to or higher than a threshold value (Threshold)

[0394] (5) In a case where a communication quality (for example, RSRP) of a cell forming area to which the terminal device 50 belongs is equal to or lower than a threshold value

[0395] (6) In a case where a communication quality (for example, RSRP) of a neighboring cell forming area is equal to or higher than a communication quality (for example, RSRP) of a cell forming area to which the neighboring cell forming area belongs by an offset amount

[0396] (7) In a case where a reception quality of the cell is better than a communication quality (for example, RSRP) of a cell to which a neighboring cell forming area belongs

[0397] (8) In a case where a communication quality (for example, RSRP) of a cell forming area to which the terminal device 50 belongs becomes worse than a first threshold value and a communication quality (for example, RSRP) of a neighboring cell forming area becomes better than a second threshold value

[0398] (9) In a case where the quality of the reference signal (e.g., CSI-RS) resource becomes better than a threshold

[0399] (10) In a case where the quality of the reference signal (e.g., CSI-RS) resource becomes higher than the reference signal to be compared by an offset amount.

[0400] Application of communication parameters

[0401] As described above, the information related to the handover of the cell-formed area can include information related to the communication parameters after the handover of the cell-formed area (hereinafter referred to as communication parameter information). After the handover of the cell-formed area, the terminal device 50 can switch the communication parameters (transmission parameters and / or reception parameters) based on the communication parameter information. The terminal device 50 can apply the communication parameters at the timing of receiving the information related to the execution of the handover of the cell-formed area, or can apply the communication parameters at a certain timing after a predetermined time.

[0402] The predetermined timing can be a timing immediately after the handover of the cell-formed area, or can be a timing at which a predetermined time has passed since the handover of the cell-formed area. Here, the predetermined time can be a time determined based on timer information or the like provided as notification in advance, or can be a time determined based on information such as a time offset.

[0403] 4-4, Skipping of processing such as random access procedure

[0404] Now, the skipping of processing such as a random access procedure will be described.

[0405] After the handover of the cell-formed area (or at the time of processing the handover of the cell-formed area), the terminal device 50 does not need to implement the processing (e.g., random access procedure and / or power control) implemented at the time of normal cell handover.

[0406] As described above, the information related to the handover of the cell-formed area can include information related to necessity / unnecessity of a random access procedure (information related to skipping of the random access procedure). In a case where the terminal device 50 determines that the random access procedure is unnecessary based on the information described above, the terminal device 50 can omit the random access procedure and immediately start data transmission. For example, by previously acquiring the information related to the handover of the cell-formed area from the base station, the terminal device 50 can implement communication without performing the random access procedure. As in the case of satellite communication, in a case where the distance to the base station can be estimated in advance, the terminal device 50 can establish uplink data communication synchronization without performing the random access procedure. The terminal device 50 can estimate the distance between the non-geostationary satellite station and the terminal from the position information, movement information, and orbit information of the non-geostationary satellite station, the position information of the terminal device 50 obtained by a global navigation satellite system (GNSS), time information, and the like.

[0407] After the handover of the cell-formed area, the terminal device 50 implements uplink transmission without implementing the random access procedure. At this time, the terminal device 50 can continue to use the timing advance value used before the handover of the cell-formed area. Alternatively, the terminal device 50 can implement communication using the timing advance based on the information related to the timing advance included in the information related to the handover of the cell-formed area.

[0408] After the handover of the cell-formed area, the terminal device 50 can continue to use the power control value used before the handover of the cell-formed area. Alternatively, the terminal device 50 can implement communication using the power control value based on the information related to the power control included in the information related to the handover of the cell-formed area.

[0409] 4-5, Continued Transmission of Same Data

[0410] Now, the continued transmission of the same data will be described.

[0411] The terminal device 50 can continue to transmit the same data as the data currently being transmitted after the handover of the cell-formed area.

[0412] For example, if the terminal device 50 was transmitting data by repeated transmission or the like before the handover of the cell-formed area, the terminal device 50 can continue to transmit the same data as the transmitted data after the handover of the cell-formed area. In the case of satellite communication, repeated transmission is effective for compensating for the degradation of transmission quality caused by long distance transmission. In a case where repeated transmission is disabled before or after the handover of the cell-formed area, the problem is the degraded transmission quality. Accordingly, by enabling repeated transmission before and after the handover of the cell-formed area, improvement in communication quality can be expected.

[0413] In a case where the same data is continued to be transmitted after the handover of the cell formation area, the base station can implement a notification related to the continuation of the transmission of the same data to the terminal device 50. The base station that implements the notification can be the base station before the handover of the cell formation area (for example, the non-terrestrial station 30 that functions as the first non-geostationary satellite station or the ground station 20 that uses the first non-geostationary satellite station as a relay station). For example, the base station can include, in the information related to the handover of the cell formation area, information indicating whether the transmission of the data being transmitted can be continued even after the handover of the cell formation area, as the notification related to the continuation of the transmission of the same data.

[0414] For example, in a case where the notification is received, the terminal device 50 does not empty the transmission data from the transmission buffer at the timing after the handover of the cell formation area, and continues the repeated transmission of the data in the transmission buffer after the handover of the cell formation area. If the notification is present, the terminal device 50 can empty the data held in the transmission buffer. In this case, the terminal device 50 needs to generate the transmission data again after the handover of the cell formation area, and unnecessary processing increases. If the notification is not present (in a case where the continuation of the transmission is possible), the terminal device 50 does not need to empty the transmission data from the transmission buffer, and thus this allows the signal processing load of the terminal device 50 to be reduced.

[0415] The base station can implement the notification related to the continuation of the transmission of the same data by the following means.

[0416] Notification means 1

[0417] The base station can implement the notification related to the continuation of the transmission of the same data quasi-statically by RRC signaling, system information, or the like.

[0418] For example, if the transmission of the data being transmitted is not completed and the handover of the cell formation area is to occur, the base station implements the notification related to the continuation of the data transmission after the handover of the cell formation area.

[0419] For example, as the notification related to the continuation of the data transmission, the base station can implement the notification of the HARQ process number. In a case where the notification is implemented, if the transmission of the data being transmitted is not completed and only the HARQ process number provided as the notification is present and the handover of the cell formation area is to occur, the terminal device 50 continues the data transmission after the handover of the cell formation area. The base station can notify only the HARQ process number before the handover of the cell formation area, can notify the HARQ process number after the handover of the cell formation area, or can notify both of the HARQ process numbers.

[0420] Notification means 2

[0421] The base station can implement the notification related to the continuation of the transmission of the same data by a MAC control element (MAC CE) or downlink control information (DCI). Specific examples of the notification means 2 include the following examples (1) and (2).

[0422] (1) Addition of a new notification field

[0423] The base station can implement the notification related to the continuation of the transmission of the data using one bit. For example, if the transmission of the data being transmitted is not completed and the handover of the cell-formed area is to occur, the base station implements the notification related to the continuation of the transmission of the data after the handover of the cell-formed area using one bit. For example, "1" indicates the continuation of the data transmission, and "0" indicates the non-continuation of the data transmission. At this time, the terminal device 50 needs to indicate the information of the data to be continuously transmitted, which is the same as the data transmitted before the handover of the cell-formed area. For example, the terminal device 50 refers to the HARQ process number provided as the notification in another field. Subsequently, the terminal device 50 continues to transmit the data of which the number in the respective HARQ process numbers before the handover of the cell-formed area is the same as the HARQ process number provided as the notification.

[0424] The base station can implement the notification related to the continuation of the transmission of the data using a plurality of bits. For example, the base station can notify the terminal device 50 of which data of the HARQ process numbers before the handover of the cell-formed area is to be continuously transmitted using a plurality of bits. For example, in the case of being notified of "0001", the terminal device 50 continues to transmit the data of the HARQ process number "0001" before the handover of the cell-formed area. At this time, the HARQ process number after the handover of the cell-formed area can be different from the HARQ process number before the handover of the cell-formed area. For example, for the HARQ process number "0001" before the handover of the cell-formed area, the terminal device 50 can continue the transmission of the HARQ process number "0010" after the handover of the cell-formed area. The base station can use one of the plurality of bits as a flag indicating whether the terminal device 50 implements the continuation of the transmission of the transmitted data before the handover of the cell-formed area.

[0425] (2) Notification by NDI

[0426] The base station can implement the notification related to the continuation of the transmission of the data using a new data indicator (NDI). If the notification indicating the continuation of the data transmission is received, the notified HARQ process is the same as the HARQ process implemented to be transmitted before the handover of the cell-formed area, and the NDI indicates the retransmission, the terminal device 50 continues the repeated transmission of the data transmitted before the handover of the cell-formed area.

[0427] Notification means 3

[0428] In a case where the HARQ process of the data transmitted before the switching of the cell forming area is the same as the HARQ process notified, the terminal device 50 can continue to transmit the data after the switching of the cell forming area. In the DCI, which HARQ process data is provided to be transmitted as the notification in the HARQ process number field. For example, if the notification of the continuation of the data transmission such as RRC signaling or the like is implemented, and the transmission of the data (the data transmitted before the switching of the cell forming area) transmitted with the same HARQ process number as the HARQ process number provided as the notification is not completed, the terminal device 50 continues the repeated transmission of the data after the switching of the cell forming area.

[0429] 4-6, Communication between base stations

[0430] The communication between the base stations will now be described.

[0431] The cooperation between the base stations (between the non-geostationary satellite stations) is necessary at the time of switching the cell forming area. For example, the base station before the switching of the cell forming area (hereinafter referred to as a first base station) can notify in advance the base station after the switching of the cell forming area (hereinafter referred to as a second base station) of the information indicated in the specific examples below. Alternatively, the second base station after the switching of the cell forming area can notify in advance the first base station before the switching of the cell forming area of the information indicated in the specific examples below.

[0432] For example, the first base station notifies in advance the second base station of the information necessary after the terminal device 50 is connected to the second base station (the second non-geostationary satellite station) before the terminal device 50 switches the communication area. The second base station notifies in advance the first base station of the information necessary for the terminal device 50 to communicate with the second base station (the second non-geostationary satellite station) before the terminal device 50 switches the communication area. The first base station generates the information related to the switching of the cell area based on the information received from the second base station.

[0433] Specific examples of the information transmitted and received between the base stations will be described below. It should be noted that the statements regarding the first base station in the following description can be replaced with the first non-geostationary satellite station. The statements regarding the second base station in the following description can be replaced with the second non-geostationary satellite station.

[0434] Received data received before the switching of the cell forming area

[0435] The first base station can transmit the received data received from the terminal device 50 to the second base station before the switching of the cell forming area.

[0436] Information necessary for implementing the continuation of the same data

[0437] The first base station / second base station transmits to the other base station information necessary for the terminal device 50 / second base station to continue transmitting the same data after the handover of the cell formation area. The information can include the information shown in (1) to (5) below.

[0438] (1) HARQ process number

[0439] (2) Number of times of transmission and reception that have been completed (for example, number of times of transmission and reception implemented until which number of repeated transmissions of M times)

[0440] (3) Terminal identification ID such as C-RNTI

[0441] (4) Configuration value necessary for scrambling sequence generation (for example, dataScramblingIdentityPUSCH, dataScramblingIdentityPDSCH, and the like)

[0442] (5) Physical layer cell identity

[0443] Information related to communication parameters

[0444] The second base station can transmit to the first base station information related to communication parameters after the handover of the cell formation area. The information can include the information indicated in (1) to (10) below.

[0445] (1) Information related to terminal-specific timing advance and / or cell-common timing advance after the handover of the cell formation area

[0446] (2) Information related to transmission timing (frame) synchronization after the handover of the cell formation area

[0447] (3) Terminal-unique ID (C-RNTI) after the handover of the cell formation area

[0448] (4) Information related to frequency band after the handover of the cell formation area

[0449] (5) SSB index after the handover of the cell formation area

[0450] (6) Information related to transmission weight after the handover of the cell formation area

[0451] (7) Information related to number of times of repeated transmission after the handover of the cell formation area

[0452] (8) Information related to HARQ disabling after the handover of the cell formation area

[0453] (9) Information related to transmission power after switching of the cell-formed area

[0454] (10) Information related to position, orbit, time, and altitude of the satellite device after switching of the cell-formed area

[0455] Information related to the random access procedure

[0456] The second base station can transmit to the first base station information necessary for the terminal device 50 to perform the random access procedure after switching of the cell-formed area. The information can include the information indicated in (1) to (6) below.

[0457] (1) Resource for physical random access channel (PRACH) transmission after switching of the cell-formed area

[0458] (2) Preamble sequence after switching of the cell-formed area

[0459] (3) Cell ID after switching of the cell-formed area

[0460] (4) Uplink / downlink carrier frequency after switching of the cell-formed area

[0461] (5) Bandwidth after switching of the cell-formed area

[0462] (6) Radio resource configuration after switching of the cell-formed area

[0463] 5. Sequence example

[0464] Based on the foregoing, sequence examples at the time of switching of the cell-formed area (sequence example 1 and sequence example 2) will be described. In sequence example 1, an example of detecting a trigger for switching the cell-formed area at the initiative of the base station will be described. In sequence example 2, an example of triggering detection of a trigger for switching the cell-formed area at the initiative of the terminal device 50 will be described.

[0465] In the sequence examples below, the first base station indicates the base station before switching of the cell-formed area, and the second base station indicates the base station after switching of the cell-formed area.

[0466] The first base station and the second base station can each be a non-terrestrial station 30 (e.g., a non-geostationary satellite station). In the case where the first base station is a non-geostationary satellite station, the statement regarding the first base station can be replaced with a first non-geostationary satellite station. In the case where the second base station is a non-geostationary satellite station, the statement regarding the second base station can be replaced with a second non-geostationary satellite station.

[0467] The first base station and the second base station are each not limited to the non-terrestrial station 30. The first base station and the second base station can be a terrestrial station 20 that uses the non-terrestrial station 30 as a relay station. For example, the first base station can be a terrestrial station 20 that uses a first non-geostationary satellite station as a relay station. The second base station can be a terrestrial station 20 that uses a second non-geostationary satellite station as a relay station. It should be noted that, in a case where the first base station and the second base station are base stations that use the non-terrestrial station 30 as a relay station, the first base station and the second base station can be one base station. In this case, the communication between the first base station and the second base station described below can be regarded as data movement within the base station.

[0468] 5-1, Sequence Example 1

[0469] Figure 15 is a diagram illustrating a sequence example at the time of handover of a cell formation area. As described earlier, in Sequence Example 1, detection of a trigger for handover of a cell formation area is made at the initiative of a base station. Hereinafter, a process of handover of a cell formation area according to Sequence 1 will be described with reference to Figure 15

[0470] First, the first base station transmits a downlink synchronization signal to the ground (step S101). The terminal device 50 establishes downlink synchronization with the first base station based on the downlink synchronization signal from the first base station. The first base station transmits system information to the ground (step S102). The terminal device 50 acquires the system information from the first base station.

[0471] Subsequently, the first base station and the terminal device 50 perform a random access procedure (step S103). During or after the random access, the terminal device 50 notifies the first base station of information related to the capability of the terminal device 50 (step S104).

[0472] The first base station (e.g., the notification portion 331 of the non-terrestrial station 30) transmits information related to handover of a cell formation area (hereinafter also referred to as connection handover information) to the terminal device 50 (step S105). For example, the first base station notifies the terminal device 50 of information necessary for communication (transmission and / or reception) at the time of handover of a cell formation area. At this time, the first base station can perform notification of both information necessary for communication in a cell formation area before handover (hereinafter also referred to as a first cell formation area) and information necessary for communication in a cell formation area after handover (hereinafter also referred to as a second cell formation area). Here, the first cell formation area is a cell formation area formed by a first geostationary satellite station. The second cell formation area is a cell formation area formed by a second geostationary satellite station.

[0473] ​It should be noted that the first base station (e.g., the reception section 332 of the non-terrestrial station 30) can acquire in advance the information for generating the connection handover information (e.g., the information necessary for the terminal device 50 to perform communication in the second cell formation area) from the second base station before transmitting the connection handover information to the terminal device 50.

[0474] The acquisition section 531 of the terminal device 50 acquires the connection handover information from the first base station. Subsequently, the configuration section 532 of the terminal device 50 performs configuration based on the information necessary for communication with the first base station (step S106). Hereinafter, the configuration here is also referred to as first base station configuration. Subsequently, the communication control section 534 of the terminal device 50 performs communication with the first base station (step S107).

[0475] Subsequently, the terminal device 50 detects whether or not the trigger for switching the cell formation area occurs (step S108). When the trigger for switching the cell formation area occurs, the terminal device 50 notifies the first base station of the occurrence of the switching trigger (step S109). It should be noted that in Sequence Example 1, the terminal device 50 initiates detection of the trigger, but the base station can initiate detection of the switching trigger. This will be described in Sequence Example 2, which will be described below.

[0476] The first base station requests the second base station, which is the switching destination of the cell formation area, to switch the cell formation area (step S110). In response to the request, the second base station transmits ACK / NACK (step S111). Hereinafter, the description will be continued on the assumption that the second base station has transmitted ACK.

[0477] The first base station (e.g., the transmission section 333 of the non-terrestrial station 30) notifies the second base station of the context information held therein (step S112). In response to the notification, the second base station transmits ACK / NACK (step S113). Hereinafter, the description will be continued on the assumption that the second base station has transmitted ACK.

[0478] The first base station notifies the terminal device 50 of the switching of the cell formation area (step S114). Upon receiving the notification from the first base station, the switching processing section 533 of the terminal device 50 switches the first base station configuration to the second base station configuration (step S115). The second base station configuration is a configuration based on the information necessary for communication in the second cell formation area. Accordingly, the terminal device 50 can switch the connection from the first base station to the second base station without handover (that is, without performing a random access procedure).

[0479] At this time, the terminal device 50 can update the connection switching information (for example, information necessary for communication at the time of switching of the cell-formed area) to new information (step S116). For example, the second base station (for example, the notification section 331 of the non-terrestrial station 30) can transmit the connection switching information (for example, information necessary for communication at the time of switching of the cell-formed area) to the terminal device 50. Subsequently, the terminal device 50 can update the connection switching information to the connection switching information received from the second base station.

[0480] The communication control section 534 of the terminal device 50 continues the communication with the second base station using the second base station configuration (step S117).

[0481] 5-2, Sequence Example 2

[0482] Figure 16 is a diagram illustrating another sequence example of switching of the cell-formed area. As described above, in the sequence example 2, the terminal device 50 initiates detection of a trigger for switching the cell-formed area. Hereinafter, the processing of switching the cell-formed area according to the sequence 2 will be described with reference to Figure 16

[0483] First, the first base station transmits a downlink synchronization signal to the ground (step S201). The terminal device 50 establishes downlink synchronization with the first base station based on the downlink synchronization signal from the first base station. The first base station transmits system information to the ground (step S202). The terminal device 50 acquires the system information from the first base station.

[0484] Subsequently, the first base station and the terminal device 50 perform a random access procedure (step S203). During or after the random access, the terminal device 50 notifies the first base station of information related to the capability of the terminal device 50 (step S204).

[0485] The first base station (for example, the notification section 331 of the non-terrestrial station 30) transmits information related to switching of the cell-formed area (hereinafter also referred to as connection switching information) to the terminal device 50 (step S205). For example, the first base station notifies the terminal device 50 of information necessary for communication (transmission and / or reception) at the time of switching of the cell-formed area. At this time, the first base station can perform notification of both information necessary for communication in the cell-formed area before switching (hereinafter also referred to as the first cell-formed area) and information necessary for communication in the cell-formed area after switching (hereinafter also referred to as the second cell-formed area). Here, the first cell-formed area is a cell-formed area formed by the first geostationary satellite station. The second cell-formed area is a cell-formed area formed by the second geostationary satellite station.

[0486] ​It should be noted that the first base station (e.g., the reception section 332 of the non-terrestrial station 30) can acquire in advance the information for generating the connection switching information (e.g., the information necessary for the terminal device 50 to perform communication in the second cell formation area) from the second base station before transmitting the connection switching information to the terminal device 50.

[0487] The acquisition section 531 of the terminal device 50 acquires the connection switching information from the first base station. Subsequently, the configuration section 532 of the terminal device 50 performs configuration based on the information necessary for communication with the first base station (step S206). Hereinafter, the configuration here is also referred to as first base station configuration. Subsequently, the communication control section 534 of the terminal device 50 performs communication with the first base station (step S207).

[0488] Subsequently, the first base station detects whether the trigger for switching the cell formation area occurs (step S208). When the trigger for switching the cell formation area occurs, the first base station requests the second base station, which is the switching destination of the cell formation area, to switch the cell formation area (step S209). In response to the request, the second base station transmits ACK / NACK (step S210). Hereinafter, the description will be continued on the assumption that the second base station has transmitted ACK.

[0489] The first base station (e.g., the transmission section 333 of the non-terrestrial station 30) notifies the second base station of the context information held therein (step S211). In response to the notification, the second base station transmits ACK / NACK (step S212). Hereinafter, the description will be continued on the assumption that the second base station has transmitted ACK.

[0490] The first base station notifies the terminal device 50 of the switching of the cell formation area (step S213). Upon receiving the notification from the first base station, the switching processing section 533 of the terminal device 50 switches the first base station configuration to the second base station configuration (step S214). The second base station configuration is a configuration based on the information necessary for communication in the second cell formation area.

[0491] At this time, the terminal device 50 can update the connection switching information (e.g., the information necessary for communication at the time of switching the cell formation area) to new information (step S215). For example, the second base station can transmit the connection switching information (e.g., the information necessary for communication at the time of switching the cell formation area) to the terminal device 50. Subsequently, the terminal device 50 can update the connection switching information to the connection switching information received from the second base station.

[0492] The communication control section 534 of the terminal device 50 continues communication with the second base station using the second base station configuration (step S216).

[0493] 6、Variation

[0494] The embodiments described above are merely examples, and various modifications and applications are possible.

[0495] For example, in the embodiments described above, the base station that communicates with the terminal device 50 is a non-geostationary satellite station or a ground station 20 that uses a non-geostationary satellite station as a relay station, but the base station is not limited to this. For example, the base station can be an aircraft station or a ground station that uses an aircraft station as a relay station. In this case, the description described above with respect to the non-geostationary satellite station (e.g., the first non-geostationary satellite station and / or the second non-geostationary satellite station) can be replaced with an aircraft station (e.g., the first aircraft station and / or the second aircraft station) as appropriate. The base station can be a non-terrestrial station 30 (e.g., a geostationary satellite station, a non-geostationary satellite station, or an aircraft station) that uses a non-geostationary satellite station or an aircraft station as a relay station.

[0496] The control device that controls the management device 10, the ground station 20, the non-terrestrial station 30, the relay station 40, and the terminal device 50 according to the present embodiment can be implemented by a special-purpose computer system or a general-purpose computer system.

[0497] For example, a communication program for executing the operations described above is stored in a computer-readable recording medium such as an optical disc, a semiconductor memory, a magnetic tape, or a flexible disc, for distribution. Subsequently, for example, the program is installed in a computer and the processing described above is executed, thereby configuring the control device. At this time, the control device can be an external device (e.g., a personal computer) of the management device 10, the ground station 20, the non-terrestrial station 30, the relay station 40, or the terminal device 50. The control device can be an internal device (e.g., the control portion 13, the control portion 23, the control portion 33, the control portion 43, or the control portion 53) of the management device 10, the ground station 20, the non-terrestrial station 30, the relay station 40, or the terminal device 50.

[0498] The communication program can be stored in a disc device included in a server device on a network such as the Internet, to allow downloading to a computer or the like. The functions described above can be realized by cooperation between an operating system (OS) and application software. In this case, a part other than the OS can be stored in a medium for distribution, or a part other than the OS can be stored in a server device to allow downloading to a computer or the like.

[0499] Among the processing operations described in the embodiments described above, all or some of the processing operations described as being automatically implemented can be manually implemented, or all or some of the processing operations described as being manually implemented can be automatically implemented by known methods. Furthermore, unless otherwise indicated, the processing procedures, specific names, and information including various data and parameters described in the foregoing documents and drawings can be arbitrarily changed. For example, the various types of information shown in the drawings are not limited to the information shown.

[0500] The components of the apparatus shown in the drawings are conceptual and are not necessarily physically configured as shown in the drawings. That is, the specific form of distribution and integration of the apparatus is not limited to the form shown in the drawings, and all or some of the apparatuses can be configured to be distributed or integrated in any unit in terms of function or physically according to various loads, usage conditions, and the like.

[0501] The embodiments described above can be appropriately combined within a range in which the processing contents do not conflict with each other. The order of the steps shown in the flowcharts or sequence diagrams of the embodiments described above can be appropriately changed.

[0502] For example, the embodiments can each be realized as any configuration constituting an apparatus or a system, such as a processor of a system large-scale integration (LSI) or the like, a module each using a plurality of processors or the like, a unit using a plurality of modules or the like, a set including a unit to which further other functions are added, or the like (that is, a configuration of a part of the apparatus).

[0503] It should be noted that, in the embodiments, a system means a set of a plurality of components (apparatuses, modules (parts), and the like), and it does not matter whether all the components are in the same housing. Thus, a system refers to both a plurality of apparatuses housed in separate housings and connected through a network and one apparatus housing a plurality of modules in one housing.

[0504] For example, the embodiments can employ a configuration of cloud computing in which a plurality of apparatuses implement processing of one function in a shared and cooperative manner through a network.

[0505] 7. Conclusion

[0506] As described above, the communication system 1 of the embodiments includes a base station and a terminal apparatus 50. The base station is a non-terrestrial station connected to the terminal apparatus as a first non-geostationary satellite station among a plurality of non-geostationary satellite stations forming a geostationary cell. Alternatively, the base station is a terrestrial station connected to the terminal apparatus using the first non-geostationary satellite station as a relay station.

[0507] Before the terminal device 50 switches the connection from the first non-geostationary satellite station to the second non-geostationary satellite station, the base station notifies the terminal device 50 in advance of information related to the switching of the connection from the first non-geostationary satellite station to the second non-geostationary satellite station. Based on the information related to the switching of the connection, the terminal device switches the connection from the first non-geostationary satellite station to the second non-geostationary satellite station without handover, that is, without performing a random access procedure.

[0508] In this way, the terminal device 50 acquires in advance from the non-geostationary satellite station the information related to the switching of the connection before switching the connection. Therefore, even in a case where the terminal device performs communication using a non-terrestrial network and the non-terrestrial network uses earth-fixed cells, the terminal device can smoothly switch the connection using the information related to the switching of the connection. As a result, the terminal device 50 can realize communication with high communication performance.

[0509] Effects of the embodiments described in this specification are merely exemplary and are not limited to the effects described in this specification.

[0510] Note that the present technology can also take the following configurations.

[0511] (1) A communication device connected to a first non-geostationary satellite station among a plurality of non-geostationary satellite stations that form location-fixed cells on the ground, the communication device comprising:

[0512] an acquisition section configured to acquire in advance from the first non-geostationary satellite station, before a switching process, information related to the switching of a connection from the first non-geostationary satellite station to a second non-geostationary satellite station among the plurality of non-geostationary satellite stations; and

[0513] a switching process section configured to switch the connection from the first non-geostationary satellite station to the second non-geostationary satellite station without performing a random access procedure, based on the information related to the switching of the connection.

[0514] (2) The communication device according to (1),

[0515] wherein the information related to the switching of the connection includes information used to determine whether a random access procedure is necessary for switching the connection, and

[0516] in a case where the random access procedure is determined to be unnecessary, the switching process section switches the connection from the first non-geostationary satellite station to the second non-geostationary satellite station without performing the random access procedure.

[0517] (3) The communication device according to (1) or (2),

[0518] The information related to connection switching may include information related to the execution of connection switching.

[0519] If the information related to the connection handover includes information related to the execution of the connection handover, the handover processing unit shall, at a predetermined time after receiving the information related to the connection handover, begin the handover process of handing over the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station.

[0520] (4) Based on the communication equipment in (1) or (2),

[0521] The information related to connection switching includes triggering information for performing connection switching, and

[0522] The handover process begins at a timing determined based on the trigger information, switching the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station.

[0523] (5) Based on the communication equipment in (4),

[0524] The triggering information includes timer information related to connection switching, and

[0525] The switching process begins at the time determined by the timer information.

[0526] (6) Based on the communication equipment in (4),

[0527] The triggering information includes information related to the start time of the connection switch, and

[0528] The handover process begins when the start time for the handover connection is reached.

[0529] (7) Based on the communication equipment in (4),

[0530] The triggering information includes location information of at least one of the first non-geosynchronous satellite station, the second non-geosynchronous satellite station, or the communication device.

[0531] If the location of at least one of the first non-geosynchronous satellite station, the second non-geosynchronous satellite station, or the communication equipment coincides with the location indicated by the location information, the handover processing unit begins the handover process.

[0532] (8) The communication device according to (1) or (2), wherein the information related to the switching of the connection includes information related to the communication operation of the communication device during the switching of the connection.

[0533] (9) The communication device according to (1) or (2), wherein the information related to the switching of the connection includes information related to the communication parameters after the switching of the connection.

[0534] (10) The communication device according to (9), wherein the information related to the communication parameters includes at least one of the following: information related to timing advance, information related to transmission timing synchronization, information related to transmission weight, information related to HARQ disable, or information related to transmission power.

[0535] (11) The communication device according to (1) or (2), wherein the information related to the switching of the connection includes information necessary for the random access procedure after the switching of the connection.

[0536] (12) The communication device according to (1) or (2), wherein the information related to the switching of the connection includes information indicating whether the data being transmitted can continue to be transmitted even after the switching of the connection.

[0537] (13) A communication device, which is connected to a terminal device as a first non-geosynchronous satellite station among a plurality of non-geosynchronous satellite stations forming a fixed-location cell on the ground, or connected to a terminal device via the first non-geosynchronous satellite station, the communication device comprising:

[0538] The notification section is configured to notify the terminal device in advance of information related to the connection switch from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station before the terminal device switches the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station among the plurality of non-geosynchronous satellite stations without performing a random access process.

[0539] (14) The communication equipment according to (13) also includes:

[0540] The transmitting section is configured to send, in advance, the information necessary for the terminal device to connect to the second non-geosynchronous satellite station before the terminal device performs the handover process.

[0541] (15) The communication equipment according to (13) or (14) also includes:

[0542] The receiving unit is configured to receive, in advance, from the second non-geosynchronous satellite station the information necessary for communication between the terminal equipment and the second non-geosynchronous satellite station before the terminal equipment performs the handover process.

[0543] The notification section generates information related to the connection switch based on information received from the second non-geosynchronous satellite station.

[0544] (16) According to the communication equipment of (15), wherein the receiving part receives from the second non-geosynchronous satellite station information related to the communication parameters necessary for communication between the terminal equipment and the second non-geosynchronous satellite station, and

[0545] The notification section generates information related to connection switching based on the information associated with the communication parameters.

[0546] (17) Based on the communication equipment of (15) or (16),

[0547] The receiving section receives information from the second non-geosynchronous satellite station necessary for the random access procedure between the terminal equipment and the second non-geosynchronous satellite station, and

[0548] The notification section generates the information related to connection handover based on the information necessary for the random access procedure.

[0549] (18) A communication method performed by communication equipment connected to a first non-geosynchronous satellite station among a plurality of non-geosynchronous satellite stations forming a fixed-location cellular network on the ground, the communication method comprising:

[0550] Prior to the handover process, information related to the handover of the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station among the plurality of non-geosynchronous satellite stations is obtained from the first non-geosynchronous satellite station; and

[0551] Based on the information related to the connection switching, the connection is switched from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station without a random access procedure.

[0552] (19) A communication method performed by a communication device connected to a terminal device or connected to the terminal device via the first non-geosynchronous satellite station, which is one of a plurality of non-geosynchronous satellite stations forming a fixed-position cell on the ground, the communication method comprising:

[0553] Before switching the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station among the plurality of non-geosynchronous satellite stations without performing a random access process, the terminal device is notified in advance of information related to the switching of the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station.

[0554] (20) A communication system comprising: a terminal device connected to a first non-geosynchronous satellite station among a plurality of non-geosynchronous satellite stations forming a fixed-location cellular network on the ground; and a base station connected to the terminal device as or through the first non-geosynchronous satellite station.

[0555] The base station includes:

[0556] The notification section is configured to notify the terminal device in advance of information related to the connection switch from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station before the terminal device switches the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station among the plurality of non-geosynchronous satellite stations without performing a random access procedure.

[0557] The terminal device includes:

[0558] The acquisition section is configured to acquire, prior to the handover process, information related to the handover of the connection from the first non-geosynchronous satellite station to a second non-geosynchronous satellite station among the plurality of non-geosynchronous satellite stations; and

[0559] The handover processing section is configured to switch the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station without performing a random access procedure, based on the information related to the handover of the connection.

[0560] List of reference numerals

[0561] 1—Communication System

[0562] 10 - Management Equipment

[0563] 20 - Ground Station

[0564] 30 - Non-Ground Stations

[0565] 40 - Relay Station

[0566] 50—Terminal Equipment

[0567] 11——Communication part

[0568] 21, 31, 41, 51 – Radio communication section

[0569] 12, 22, 32, 42, 52 — Storage section

[0570] 13, 23, 33, 43, 53 — Control section

[0571] 24, 44 – Network Communication Section

[0572] 211, 311, 411, 511 – Receiving and Processing Section

[0573] 212, 312, 412, 512 — Transmission Processing Section

[0574] 213, 313, 413, 513 — Antenna

[0575] 331 - Notification Section

[0576] 332 - Receiver Section

[0577] 333 - Sending section

[0578] 334, 534 – Communication Control Section

[0579] 531 - Acquiring Part

[0580] 532 - Configuration Section

[0581] 533 - Switching Processing Section

Claims

1. A communication device connected to a first non-geosynchronous satellite station among a plurality of non-geosynchronous satellite stations forming a fixed-location cellular network on the ground, the communication device comprising: The acquisition section is configured to acquire, in advance, information related to the handover of the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station among the plurality of non-geosynchronous satellite stations from the first non-geosynchronous satellite station before the handover process. as well as The handover processing section is configured to switch the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station without performing a random access procedure, based on the information related to the handover of the connection.

2. The communication device according to claim 1, wherein The information related to connection handover includes information for determining whether a random access procedure is necessary for the connection handover, and If the random access procedure is determined to be unnecessary, the handover process will switch the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station without performing the random access procedure.

3. The communication device according to claim 1, wherein... The information related to connection switching can include information related to the execution of the connection switching. If the information related to the connection handover includes information related to the execution of the connection handover, the handover processing unit shall, at a predetermined time after receiving the information related to the connection handover, begin the handover process of handing over the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station.

4. The communication device according to claim 1, wherein The information related to connection switching includes triggering information for performing connection switching, and The handover process begins at a timing determined based on the trigger information, switching the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station.

5. The communication device according to claim 4, wherein The triggering information includes timer information related to connection switching, and The switching process begins at the time determined by the timer information.

6. The communication device according to claim 4, wherein The triggering information includes information related to the start time of the connection switch, and The handover process begins when the start time for the handover connection is reached.

7. The communication device according to claim 4, wherein The triggering information includes the location information of at least one of the first non-geosynchronous satellite station, the second non-geosynchronous satellite station, or the communication device, and If the location of at least one of the first non-geosynchronous satellite station, the second non-geosynchronous satellite station, or the communication equipment coincides with the location indicated by the location information, the handover processing unit begins the handover process.

8. The communication device according to claim 1, wherein The information related to connection switching includes information related to the communication operation of the communication device during connection switching.

9. The communication device according to claim 1, wherein The information related to the switching of connections includes information related to communication parameters after the switching of connections.

10. The communication device according to claim 9, wherein The information related to communication parameters includes at least one of the following: information related to timing advance, information related to transmission timing synchronization, information related to transmission weight, information related to HARQ disabling, or information related to transmission power.

11. The communication device according to claim 1, wherein The information related to connection switching includes information necessary for the random access procedure following connection switching.

12. The communication device according to claim 1, wherein The information related to the switching of connections includes information indicating whether data being transmitted can continue to be sent even after the connection is switched.

13. A communication device, which connects to or is connected to a terminal device via a first non-geosynchronous satellite station of a plurality of non-geosynchronous satellite stations forming a fixed-location cellular network on the ground, the communication device comprising: The notification section is configured to notify the terminal device in advance of information related to the connection switch from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station before the terminal device switches the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station among the plurality of non-geosynchronous satellite stations without performing a random access process.

14. The communication device according to claim 13, further comprising: The transmitting section is configured to send, in advance, the information necessary for the terminal device to connect to the second non-geosynchronous satellite station before the terminal device performs the handover process.

15. The communication device according to claim 13, further comprising: The receiving section is configured to receive, before the terminal device performs handover processing, information necessary for communication between the terminal device and the second non-geosynchronous satellite station from the second non-geosynchronous satellite station, wherein... The notification section generates the information related to the handover of the connection based on information received from the second non-geosynchronous satellite station.

16. The communication device according to claim 15, wherein The receiving unit receives information from the second non-geosynchronous satellite station related to the communication parameters necessary for communication between the terminal equipment and the second non-geosynchronous satellite station, and The notification section generates information related to connection switching based on the information associated with the communication parameters.

17. The communication device according to claim 15, wherein The receiving unit receives information from the second non-geosynchronous satellite station necessary for the random access procedure between the terminal equipment and the second non-geosynchronous satellite station, and The notification section generates the information related to connection handover based on the information necessary for the random access procedure.

18. A communication method performed by communication equipment connected to a first non-geosynchronous satellite station among a plurality of non-geosynchronous satellite stations forming a fixed-location cellular network on the ground, the communication method comprising: Prior to the handover process, information related to the handover of the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station among the plurality of non-geosynchronous satellite stations is obtained from the first non-geosynchronous satellite station. as well as Based on the information related to the connection switching, the connection is switched from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station without a random access procedure.

19. A communication method performed by a communication device connected to a terminal device, or connected to the terminal device via the first non-geosynchronous satellite station, which is one of a plurality of non-geosynchronous satellite stations forming a fixed-position cell on the ground, the communication method comprising: Before switching the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station among the plurality of non-geosynchronous satellite stations without performing a random access process, the terminal device is notified in advance of information related to the switching of the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station.

20. A communication system, comprising: Terminal equipment connected to the first non-geosynchronous satellite station among multiple non-geosynchronous satellite stations forming a fixed-location cellular network on the ground; And a base station that serves as the first non-geosynchronous satellite station or is connected to the terminal device via the first non-geosynchronous satellite station. The base station includes: The notification section is configured to notify the terminal device in advance of information related to the connection switch from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station before the terminal device switches the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station among the plurality of non-geosynchronous satellite stations without performing a random access procedure. The terminal device includes: The acquisition section is configured to acquire, prior to the handover process, information related to the handover of the connection from the first non-geosynchronous satellite station to a second non-geosynchronous satellite station among the plurality of non-geosynchronous satellite stations; and The handover processing section is configured to switch the connection from the first non-geosynchronous satellite station to the second non-geosynchronous satellite station without performing a random access procedure, based on the information related to the handover of the connection.

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