Non-terrestrial station device, communication device, and communication method

Abstract

To provide a communication device and a communication method that further improve the quality between wireless links in a communication system in which a base station device and a communication device communicate with each other.SOLUTION: A communication device (50) includes a receiver (511a) and a transmitter (512d). The receiver (511a) receives a synchronization signal transmitted from a base station device (20, 30). The transmitter (512d) transmits, to the base station device (20, 30), a physical random access channel (PRACH) including a feature capable of uniquely identifying the synchronization signal and / or a PRACH resource received by the receiver (511a).SELECTED DRAWING: Figure 15

Description

[Technical field]

[0001] The present disclosure relates to non-ground station devices, communication devices, and communication methods. [Background technology]

[0002] Mobile communications using wireless access technologies such as cellular communication technologies are known. In such wireless access technologies, as a communication device such as a cellular phone moves, a wireless base station device (hereinafter referred to as a base station device or a base station) to which the communication device is connected is switched. In addition to terrestrial stations installed on the ground, non-terrestrial stations in the sky, such as artificial satellites, are being considered as base stations. In addition to wireless communication via terrestrial stations by connecting to terrestrial stations, wireless communication via non-terrestrial stations by connecting to non-terrestrial stations is being considered for the communication device. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] RP-182880, Thales, “Study on solutions for NR to support non-terrestrial networks (NTN),” 3GPP TSG RAN Meeting#82, Sorrento, Italy, December, 2018. Summary of the Invention [Problem to be solved by the invention]

[0004] However, in wireless communication between a communication device and a non-terrestrial station, the propagation delay is larger than that in wireless communication with a terrestrial station, and therefore, when the non-terrestrial station performs wireless communication with a terrestrial communication device, the non-terrestrial station cannot accurately calculate the propagation delay, which may result in a deterioration in the quality of the wireless link.

[0005] Therefore, the present disclosure proposes a non-terrestrial station device, a communication device, and a communication method that can further improve the quality between wireless links in a communication system in which a base station device and a communication device communicate with each other. [Means for solving the problem]

[0006] A non-terrestrial station device according to the present disclosure wirelessly communicates with a communication device. The non-terrestrial station device includes a transmitter and a receiver. The transmitter transmits orbit information of the non-terrestrial station device. The receiver receives a predetermined signal transmitted at a timing adjusted by the communication device. The adjusted timing is calculated by the communication device based on the orbit information of the non-terrestrial station device and position information of the communication device. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating a configuration example of a communication system according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is a diagram illustrating an example of a wireless network provided by a communication system. [Diagram 3] FIG. 1 is a diagram showing an overview of satellite communication provided by a communication system. [Figure 4] FIG. 2 is a diagram showing an example of a cell formed by a satellite station; [Diagram 5] FIG. 2 is a diagram illustrating a configuration example of a management device according to an embodiment of the present disclosure. [Figure 6] FIG. 2 is a diagram illustrating a configuration example of a non-terrestrial station according to an embodiment of the present disclosure. [Figure 7] FIG. 2 is a diagram illustrating an example of the configuration of a ground station according to an embodiment of the present disclosure. [Figure 8] FIG. 2 is a diagram illustrating a configuration example of a relay station according to an embodiment of the present disclosure. [Figure 9] FIG. 1 is a diagram illustrating a configuration example of a communication device according to an embodiment of the present disclosure. [Figure 10] 10 is a flowchart illustrating an example of an initial connection process according to the present disclosure. [Figure 11] FIG. 2 is a sequence diagram illustrating a collision-based RACH procedure according to the present disclosure. [Figure 12] FIG. 2 is a sequence diagram illustrating a non-contention based RACH procedure according to the present disclosure. [Figure 13] FIG. 1 is a sequence diagram showing a NR 2-STEP RACH according to the present disclosure. [Figure 14] FIG. 2 is an illustration of a problem caused by propagation delay according to the present disclosure. [Figure 15] FIG. 2 is a sequence diagram showing a first communication method according to the present disclosure. [Figure 16] FIG. 11 is a sequence diagram showing a second communication method according to the present disclosure. [Figure 17] FIG. 11 is an explanatory diagram of a third communication method according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following embodiments, the same components are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0009] In addition, in this specification and drawings, multiple components having substantially the same functional configuration may be distinguished by adding different numbers after the same reference numeral. For example, multiple components having substantially the same functional configuration may be distinguished as communication devices 501, 502, and 503 as necessary. However, when there is no need to particularly distinguish between multiple components having substantially the same functional configuration, only the same reference numerals are attached. For example, when there is no need to particularly distinguish between communication devices 501, 502, and 503, they are simply referred to as communication device 50.

[0010] The present disclosure will be described in the following order. 1. Introduction 2. Embodiment 2-1. Overall configuration of the communication system 2-2. Management device configuration 2-3. Base station configuration 2-4. Relay station configuration 2-5.Communication device configuration 2-6. Initial connection process 2-7. First communication method 2-8. Second communication method 2-9. The third communication method 2-10.Effects 3. Variations 3-1. Modifications to system configuration 3-2.Other modifications 4. Conclusion

[0011] <<1. Introduction>> Radio access technologies such as LTE (Long Term Evolution) and NR (New Radio) are being considered by 3GPP (registered trademark) (3rd Generation Partnership Project). LTE and NR are types of cellular communication technologies that enable mobile communication for terminal devices by arranging multiple areas covered by base stations in the form of cells. In the following description, "LTE" includes LTE-A (LTE-Advanced), LTE-A Pro (LTE-Advanced Pro), and EUTRA (Evolved Universal Terrestrial Radio Access). NR includes NRAT (New Radio Access Technology) and FEUTRA (Further EUTRA).

[0012] NR is the next generation (5th generation) radio access technology (RAT) after LTE. NR is a radio access technology that can support various use cases including eMBB (Enhanced Mobile Broadband), mMTC (Massive Machine Type Communications), and URLLC (Ultra-Reliable and Low Latency Communications). NR is being studied with the aim of creating a technology framework that can support the usage scenarios, requirements, and deployment scenarios of these use cases.

[0013] Furthermore, in NR, due to the increasing demand for wide area coverage, connection stability, etc., a non-terrestrial network (NTN) has been started to be considered. In the non-terrestrial network, it is planned that a wireless network will be provided to terminal devices via base stations other than terrestrial stations, such as satellite stations and aircraft stations. These base stations other than terrestrial stations are called non-terrestrial stations or non-terrestrial base stations. The wireless network provided by terrestrial stations is called a terrestrial network (TN). By using the same wireless access method for the terrestrial network and the non-terrestrial network, integrated operation of the terrestrial network and the non-terrestrial network will be possible.

[0014] In the embodiments of the present disclosure, a terrestrial station (also referred to as a terrestrial base station) refers to a base station (including a relay station) installed on the ground. "Terrestrial" is defined in a broad sense to include not only ground (on land) but also underground, on water, and underwater.

[0015] <<2. Embodiment>> A communication system 1 according to this embodiment will be described below. The communication system 1 includes a non-terrestrial station and provides wireless communication using a non-terrestrial network to a communication device. The non-terrestrial network included in the communication system 1 is not limited to a wireless network using a wireless access method defined by NR. The non-terrestrial network included in the communication system 1 may be a wireless network using a wireless access method other than NR, such as LTE, W-CDMA (Wideband Code Division Multiple Access), or cdma2000 (Code Division Multiple Access 2000).

[0016] In the following description, the concept of a base station (hereinafter also referred to as a base station device) includes a relay station (hereinafter also referred to as a relay device). The concept of a base station includes not only a structure having the functions of a base station, but also devices installed in the structure. Examples of structures include buildings such as high-rise buildings, houses, steel towers, station facilities, airport facilities, port facilities, and stadiums. The concept of a structure includes not only buildings, but also non-building structures such as tunnels, bridges, dams, fences, and steel pillars, and equipment such as cranes, gates, and windmills. The concept of a structure includes not only ground (on land) or underground structures, but also structures on water such as piers and megafloats, and underwater structures such as marine observation facilities.

[0017] The base station may be a mobile base station. For example, the base station may be a device installed in a mobile body, or may be the mobile body itself. The mobile body may be a mobile terminal such as a smartphone, a mobile body moving on the ground (land) (for example, a vehicle such as a car, a bus, a truck, a train, or a linear motor car), or a mobile body moving underground (for example, in a tunnel) (for example, a subway). The mobile body may be a mobile body moving on the water (for example, a ship such as a passenger ship, a cargo ship, or a hovercraft), or a mobile body moving underwater (for example, a submarine such as a submarine, a submarine, or an unmanned submersible). The mobile body may be a mobile body moving within the atmosphere (for example, an aircraft such as an airplane, an airship, or a drone), or a space mobile body moving outside the atmosphere (for example, an artificial celestial body such as an artificial satellite, a spaceship, a space station, or a probe).

[0018] Note that an LTE base station may be referred to as an eNodeB (Evolved Node B) or eNB. Also, an NR base station may be referred to as a gNodeB or gNB. Also, in LTE and NR, a terminal device (also referred to as a mobile station, mobile station device, or terminal) may be referred to as a UE (User Equipment). Note that a terminal device is a type of communication device, and is also referred to as a mobile station, mobile station device, or terminal. In the embodiment of the present disclosure, the concept of a communication device includes not only a portable terminal device such as a mobile terminal, but also a device installed in a structure or a moving object, for example. Also, the concept of a communication device includes not only a terminal device, but also a base station and a relay station.

[0019] <2-1. Overall configuration of the communication system> 1 is a diagram showing a configuration example of a communication system 1 according to an embodiment of the present disclosure. The communication system 1 includes a management device 10, a non-terrestrial base station (hereinafter simply referred to as a non-terrestrial station) 20, a terrestrial base station (hereinafter simply referred to as a terrestrial station) 30, a relay device (hereinafter simply referred to as a relay station) 40, and a communication device 50. The communication system 1 provides a wireless network that enables mobile communication to a user by the cooperation of each wireless communication device constituting the communication system 1. The wireless communication device is a device having a wireless communication function, and in the example of FIG. 1, the non-terrestrial station 20, the terrestrial station 30, the relay station 40, and the communication device 50 correspond to the non-terrestrial station 20, the terrestrial station 30, the relay station 40, and the communication device 50.

[0020] The communication system 1 may include a plurality of management devices 10, non-terrestrial stations 20, ground stations 30, relay stations 40, and communication devices 50. In the example of Fig. 1, the communication system 1 includes management devices 101, 102, etc. as the management device 10. The communication system 1 also includes non-terrestrial stations 201, 202, etc. as the non-terrestrial stations 20, and ground stations 301, 302, etc. as the ground stations 30. The communication system 1 also includes relay stations 401, 402, etc. as the relay stations 40, and communication devices 501, 502, 503, etc. as the communication devices 50.

[0021] The management device 10 is a device that manages a wireless network. For example, the management device 10 is a device that functions as an MME (Mobility Management Entity) or an AMF (Access and Mobility Management Function). The management device 10 constitutes a core network CN. The core network CN is, for example, an EPC (Evolved Packet Core) or a 5GC (5G Core network). The management device 10 is connected to each of a plurality of non-terrestrial stations 20 and a plurality of terrestrial stations 30. The management device 10 manages communication between the non-terrestrial stations 20 and the terrestrial stations 30.

[0022] The non-terrestrial station 20 is a base station that wirelessly communicates with the communication device 50. In the example of Fig. 1, the non-terrestrial station 201 is connected to a relay station 401, and can wirelessly communicate with the communication device 50 via the relay station 401. In this embodiment, the non-terrestrial station 20 is a base station that can float in the air or space. For example, the non-terrestrial station 20 is a non-terrestrial station device such as an aircraft station or a satellite station.

[0023] The aircraft station is a wireless communication device capable of floating in the atmosphere, such as an aircraft. The aircraft station may be, for example, a device mounted on an aircraft, or may be the aircraft itself. The concept of an aircraft includes not only heavier aircraft such as airplanes and gliders, but also lighter aircraft such as balloons and airships. The concept of an aircraft includes not only heavier aircraft and lighter aircraft, but also rotorcraft such as helicopters and autogyros. The aircraft station (or an aircraft on which the aircraft station is mounted) may be an unmanned aircraft such as a drone. The concept of an unmanned aircraft also includes unmanned aerial systems (UAS) and tethered unmanned aerial systems (Tethered UAS). The concept of an unmanned aircraft also includes lighter than air UAS (LTA) and heavier than air UAS (HTA). The concept of an unmanned aircraft also includes high altitude unmanned aerial system platforms (HAPs).

[0024] A satellite station is a wireless communication device capable of floating outside the atmosphere. A satellite station may be a device mounted on a space vehicle such as an artificial satellite, or may be the space vehicle itself. A satellite serving as a satellite station may be any of a low earth orbit (LEO) satellite, a medium earth orbit (MEO) satellite, a geostationary earth orbit (GEO) satellite, and a highly elliptical orbit (HEO) satellite. Of course, a satellite station may be a device mounted on a low earth orbit satellite, a medium earth orbit satellite, a geostationary satellite, or a highly elliptical orbit satellite.

[0025] The ground station 30 is a base station that wirelessly communicates with the communication device 50. In the example of FIG. 1, the ground station 301 is connected to a relay station 402, and can wirelessly communicate with the communication device 50 via the relay station 402. The ground station 30 may be a base station installed in a structure on the ground, or a base station installed in a mobile object moving on the ground. For example, the ground station 30 is an antenna installed in a structure such as a building and a signal processing device connected to the antenna. Of course, the ground station 30 may be the structure or the mobile object itself.

[0026] The relay station 40 is a device that serves as a relay station for the base station. The relay station 40 is a type of base station. The relay station 40 relays communication between the non-terrestrial station 20 and the communication device 50, or communication between the terrestrial station 30 and the communication device 50. The relay station 40 may be a terrestrial station or a non-terrestrial station. The relay station 40, together with the non-terrestrial station 20 and the terrestrial station 30, constitutes a radio access network RAN.

[0027] The communication device 50 is, for example, a mobile phone, a smart device (smartphone or tablet), a PDA (Personal Digital Assistant), or a personal computer. The communication device 50 may be an M2M (Machine to Machine) device or an IoT (Internet of Things) device. The communication device 50 may be a wireless communication device installed in a mobile object, or may be the mobile object itself. The communication device 50 may be a relay station that relays satellite communication, or a base station that receives satellite communication. The communication device 50 supports both terrestrial networks and non-terrestrial networks. Therefore, the communication device 50 can communicate not only with terrestrial station devices such as the terrestrial station 30, but also with non-terrestrial station devices such as the non-terrestrial station 20.

[0028] 2 is a diagram showing an example of a wireless network provided by the communication system 1. The non-terrestrial station 20 and the terrestrial station 30 each constitute a cell. A cell is an area covered by wireless communication by a base station. The cell constituted by the non-terrestrial station 20 and the terrestrial station 30 may be any of a macrocell, a microcell, a femtocell, and a small cell. Note that the communication system 1 may be configured so that a single base station manages multiple cells, or so that multiple base stations manage one cell.

[0029] In the example of Fig. 2, the terrestrial stations 301 and 302 constitute a terrestrial network TN1, and the terrestrial stations 303, 304, and 305 constitute a terrestrial network TN2. The terrestrial networks TN1 and TN2 are terrestrial networks operated by a wireless communication carrier such as a telephone company. The terrestrial networks TN1 and TN2 may be operated by different wireless communication carriers or may be operated by the same wireless communication carrier. The terrestrial networks TN1 and TN2 may be considered as one terrestrial network.

[0030] The terrestrial network TN1 and the terrestrial network TN2 are each connected to a core network. In the example of FIG. 2, the terrestrial station 30 constituting the terrestrial network TN2 is connected to a core network CN constituted by the management device 101 and the like. If the radio access method of the terrestrial network TN2 is LTE, the core network CN is EPC. Also, if the radio access method of the terrestrial network TN2 is NR, the core network CN is 5GC. Of course, the core network CN is not limited to EPC or 5GC, and may be a core network of another radio access method. Note that, in the example of FIG. 2, the terrestrial network TN1 is not connected to a core network, but may be connected to the core network CN. Also, the terrestrial network TN1 may be connected to a core network (not shown) different from the core network CN.

[0031] The core network CN includes a gateway device, a gateway exchange, etc., and is connected to the public network PN via the gateway device. The public network PN is, for example, a public data network such as the Internet, a regional IP network, or a telephone network (a mobile phone network, a landline telephone network, etc.). The gateway device is, for example, a server device connected to the Internet, a regional IP network, etc. The gateway exchange is, for example, an exchange connected to a telephone network of a telephone company. The management device 101 may have a function as a gateway device or a gateway exchange.

[0032] The non-terrestrial station 20 and relay station 40 shown in FIG. 2 are both non-terrestrial station devices such as satellite stations and aircraft stations. A group of satellite stations (or a single satellite station) constituting a non-terrestrial network is called a spaceborne platform. Also, a group of aircraft stations (or a single aircraft station) constituting a non-terrestrial network is called an airborne platform. In the example of FIG. 2, the non-terrestrial station 202, the relay station 401, and the relay station 402 constitute a spaceborne platform SBP1, and the non-terrestrial station 201 constitutes a spaceborne platform SBP2. Also, the non-terrestrial station 203 constitutes an airborne platform ABP1.

[0033] The communication device 50 is capable of communicating with both the ground station 30 and the non-ground station 20. In the example of FIG. 2, the communication device 501 is capable of communicating with the ground station 30 constituting the terrestrial network TN1. The communication device 501 is also capable of communicating with the non-ground stations 20 constituting the spaceborne platforms SBP1 and SBP2. The communication device 501 is also capable of communicating with the non-ground station 20 constituting the airborne platform ABP1. The communication device 501 may be capable of directly communicating with another communication device 50 (the communication device 502 in the example of FIG. 2).

[0034] The non-terrestrial stations 20 connect to the terrestrial network or the core network via the relay station 60. The non-terrestrial stations 20 constituting the spaceborne platforms SBP1 and SBP2 connect to the terrestrial network TN1 via the relay station 601. The non-terrestrial stations 20 constituting the spaceborne platforms SBP1 and SBP2 and the airborne platform ABP1 connect to the core network CN via the relay station 602. It is also possible for the non-terrestrial stations 20 to communicate directly with each other without going through the relay station 60.

[0035] The relay station 60 is, for example, an aviation station or an earth station. An aviation station is a radio station installed on the ground or on a mobile object moving on the ground in order to communicate with an aircraft station. An earth station is a radio station located on the earth (including in the air) in order to communicate with a satellite station (space station). An earth station may be a large earth station or a small earth station such as a VSAT (Very Small Aperture Terminal). An earth station may be a VSAT control earth station (also called a master station or a HUB station) or a VSAT earth station (also called a slave station). An earth station may be a radio station installed on a mobile object moving on the ground. For example, an on-board earth station (ESV: Earth Stations on board Vessels) is an example of an earth station mounted on a ship. An earth station may include an aircraft earth station installed on an aircraft (including a helicopter) and communicating with a satellite station. An earth station may include an aircraft earth station installed on a mobile object moving on the ground and communicating with an aircraft earth station via a satellite station. The relay station 60 may be a portable, mobile radio station that communicates with a satellite station or an aircraft station. The relay station 60 may be considered as a part of the communication system 1.

[0036] Each device constituting the spaceborne platforms SBP1, SBP2 performs satellite communication with the communication device 50. Satellite communication refers to wireless communication between a satellite station and the communication device 50. Fig. 3 is a diagram showing an overview of satellite communication provided by the communication system 1. Satellite stations are mainly divided into geostationary satellite stations and low-earth orbit satellite stations.

[0037] A geostationary satellite station is located at an altitude of approximately 35,786 km, and revolves around the Earth at the same speed as the Earth's rotation speed. In the example of Fig. 3, the non-terrestrial station 201 constituting the spaceborne platform SBP2 is a geostationary satellite station. The relative speed of the geostationary satellite station with respect to the terrestrial communication device 50 is nearly zero, and it is observed by the terrestrial communication device 50 as if it were stationary. The non-terrestrial station 201 performs satellite communication with communication devices 501, 503, 504, etc. located on the Earth.

[0038] A low-earth orbit satellite station is a satellite station that orbits at a lower altitude than a geostationary satellite station or a medium-earth orbit satellite station. A low-earth orbit satellite station is a satellite station located at an altitude between 500 km and 2000 km, for example. In the example of FIG. 3, the non-ground station 20 constituting the spaceborne platform SBP1 2、 203 is a low-earth orbit satellite station. Note that FIG. 3 shows only two satellite stations, non-earth station 202 and non-earth station 203, that make up the spaceborne platform SBP1. However, in reality, the satellite stations that make up the spaceborne platform SBP1 form a low-earth orbit satellite constellation with two or more (e.g., tens to thousands) non-earth stations 20. Unlike geostationary satellite stations, low-earth orbit satellite stations have a relative speed with respect to the terrestrial communication device 50, and are observed by the terrestrial communication device 50 as if they are moving. Non-earth station 20 2、 Each of the satellites 203 constitutes a cell and performs satellite communication with communication devices 501, 502, 503, etc. located on the earth.

[0039] FIG. 4 is a diagram showing an example of a cell formed by a satellite station. FIG. 4 shows a cell C2 formed by a non-terrestrial station 203, which is a low-earth orbit satellite station. The satellite station orbiting in a low-earth orbit communicates with a terrestrial communication device 50 with a predetermined directivity to the ground. For example, the angle R1 shown in FIG. 4 is 40°. In the case of FIG. 4, the radius D1 of the cell C2 formed by the non-terrestrial station 203 is, for example, 1000 km. The low-earth orbit satellite station moves at a constant speed. When it becomes difficult for the low-earth orbit satellite station to provide satellite communication to the terrestrial communication device 50, the subsequent low-earth orbit satellite station provides satellite communication. In the case of the example of FIG. 4, when it becomes difficult for the non-terrestrial station 203 to provide satellite communication to the terrestrial communication device 50, the subsequent non-terrestrial station 204 provides satellite communication. Note that the values ​​of the angle R1 and the radius D1 described above are merely examples and are not limited to the above.

[0040] As described above, the communication device 50 is capable of wireless communication using a non-terrestrial network. The non-terrestrial station 20 and the relay station 40 of the communication system 1 constitute a non-terrestrial network. This enables the communication system 1 to extend services to the communication device 50 located in an area that cannot be covered by the terrestrial network. For example, the communication system 1 can provide public safety communication and critical communication to the communication device 50 such as an IoT (Internet of Things) device or an MTC (Machine Type Communications) device. Furthermore, the use of a non-terrestrial network improves service reliability and recovery, so that the communication system 1 can reduce the vulnerability of the service to physical attacks or natural disasters. Furthermore, the communication system 1 can realize service connection to aircraft terminal devices such as airplane passengers and drones, and service connection to mobile terminal devices such as ships and trains. In addition, the communication system 1 can realize the provision of A / V content, group communication, IoT broadcast service, software download service, highly efficient multicast services such as emergency messages, highly efficient broadcast services, and the like. Furthermore, the communication system 1 can realize traffic offload between the terrestrial network and the non-terrestrial network. To achieve these, it is desirable that the non-terrestrial network provided by the communication system 1 be operationally integrated at a higher layer with the terrestrial network provided by the communication system 1. It is also desirable that the non-terrestrial network provided by the communication system 1 and the terrestrial network provided by the communication system 1 share a radio access method.

[0041] Next, the configuration of each device constituting the communication system 1 according to this embodiment will be specifically described.

[0042] <2-2. Management device configuration> The management device 10 is a device that manages a wireless network. For example, the management device 10 is a device that manages communication between the non-terrestrial station 20 and the terrestrial station 30. If the core network is EPC, the management device 10 is a device that has a function as, for example, an MME (Mobility Management Entity). If the core network is 5GC, the management device 10 is a device that has a function as, for example, an AMF (Access and Mobility Management Function). The management device 10 may have a gateway function. For example, if the core network is EPC, the management device 10 may have a function as an S-GW (Serving Gateway) or a P-GW (Packet Data Network Gateway). If the core network is 5GC, the management device 10 may have a function as a UPF (User Plane Function). The management device 10 does not necessarily have to be a device that configures a core network. For example, if the core network is a W-CDMA or cdma2000 core network, the management device 10 may be a device that functions as an RNC (Radio Network Controller).

[0043] Fig. 5 is a diagram showing a configuration example of a management device 10 according to an embodiment of the present disclosure. The management device 10 includes a communication unit 11, a storage unit 12, and a control unit 13. Note that the configuration shown in Fig. 5 is a functional configuration, and the hardware configuration may be different from this. In addition, the functions of the management device 10 may be distributed and implemented in multiple physically separated configurations. For example, the management device 10 may be configured by multiple server devices.

[0044] The communication unit 11 is a communication interface for communicating with other devices. The communication unit 11 may be a network interface or a device connection interface. For example, the communication unit 11 may be a LAN (Local Area Network) interface such as a NIC (Network Interface Card), or a USB (Universal Serial Bus) interface configured with a USB host controller, a USB port, and the like. The communication unit 11 may be a wired interface or a wireless interface. The communication unit 11 functions as a communication means of the management device 10. The communication unit 11 communicates with the ground station 30 and the relay station 60 according to the control of the control unit 13.

[0045] The storage unit 12 is a data readable / writable storage device such as a dynamic random access memory (DRAM), a static random access memory (SRAM), a flash memory, or a hard disk. The storage unit 12 functions as a storage means of the management device 10. The storage unit 12 stores, for example, the connection state of the communication device 50. For example, the storage unit 12 stores the state of a radio resource control (RRC) or an EPS connection management (ECM) of the communication device 50. The storage unit 12 may function as a home memory that stores location information of the communication device 50.

[0046] The control unit 13 is a controller that controls each part of the management device 10. The control unit 13 is realized by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). For example, the control unit 13 is realized by the processor executing various programs stored in a storage device inside the management device 10 using a RAM (Random Access Memory) or the like as a working area. The control unit 13 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The CPU, MPU, ASIC, and FPGA can all be considered as controllers.

[0047] <2-3. Base station configuration> Next, the configuration of the base station will be described. The communication system 1 includes, as base stations, a non-terrestrial station 20 constituting a non-terrestrial network and a terrestrial station 30 constituting a terrestrial network. All of the non-terrestrial stations 20 constituting the non-terrestrial network are mobile. First, the configuration of the non-terrestrial station 20 will be described.

[0048] [Non-Ground Station] Fig. 6 is a diagram showing a configuration example of a non-terrestrial station 20 according to an embodiment of the present disclosure. The non-terrestrial station 20 includes a wireless communication unit 21, a storage unit 22, and a control unit 23. Note that the configuration shown in Fig. 6 is a functional configuration, and the hardware configuration may be different from this. Furthermore, the functions of the non-terrestrial station 20 may be distributed and implemented in multiple physically separated components.

[0049] The wireless communication unit 21 is a wireless communication interface that wirelessly communicates with other wireless communication devices (for example, the communication device 50 and the relay station 60). The wireless communication unit 21 supports one or more wireless access methods. For example, the wireless communication unit 21 supports both NR and LTE. The wireless communication unit 21 may support W-CDMA and cdma2000 in addition to NR and LTE. The wireless communication unit 21 includes a reception processing unit 211, a transmission processing unit 212, and an antenna 213. The wireless communication unit 21 may include a plurality of reception processing units 211, a plurality of transmission processing units 212, and a plurality of antennas 213. When the wireless communication unit 21 supports a plurality of wireless access methods, each unit of the wireless communication unit 21 may be configured separately for each wireless access method. For example, the reception processing unit 211 and the transmission processing unit 212 may be configured separately for LTE and NR.

[0050] The reception processing unit 211 processes an uplink signal received via the antenna 213. The reception processing unit 211 includes a radio reception unit 211a, a demultiplexing unit 211b, a demodulation unit 211c, and a decoding unit 211d.

[0051] The wireless receiver 211a performs down-conversion, removal of unnecessary frequency components, control of amplification level, orthogonal demodulation, conversion to digital signal, removal of guard interval, extraction of frequency domain signal by fast Fourier transform, etc., on the uplink signal. The demultiplexer 211b separates uplink channels such as PUSCH (Physical Uplink Shared Channel) and PUCCH (Physical Uplink Control Channel) and uplink reference signals from the signal output from the wireless receiver 211a. The demodulator 211c demodulates the received signal using a modulation method such as BPSK (Binary Phase Shift Keying) and QPSK (Quadrature Phase Shift Keying) for the modulation symbols of the uplink channel. The modulation method used by the demodulator 211c may be 16QAM (Quadrature Amplitude Modulation), 64QAM, 256QAM, etc. The decoder 211d performs decoding processing on the coded bits of the demodulated uplink channel. The decoded uplink data and uplink control information are output to the control unit 23.

[0052] The transmission processing unit 212 performs a transmission process of the downlink control information and the downlink data, and includes an encoding unit 212a, a modulation unit 212b, a multiplexing unit 212c, and a radio transmitting unit 212d.

[0053] The coding unit 212a codes the downlink control information and downlink data input from the control unit 23 using a coding method such as block coding, convolution coding, turbo coding, etc. The modulation unit 212b modulates the coded bits output from the coding unit 212a using a predetermined modulation method such as BPSK, QPSK, 16QAM, 64QAM, 256QAM, etc. The multiplexing unit 212c multiplexes the modulation symbols of each channel and the downlink reference signal, and places them in a predetermined resource element. The wireless transmission unit 212d performs various signal processing on the signal from the multiplexing unit 212c. For example, the wireless transmission unit 212d performs processing such as conversion to the time domain by fast Fourier transform, addition of a guard interval, generation of a baseband digital signal, conversion to an analog signal, quadrature modulation, up-conversion, removal of unnecessary frequency components, and power amplification. The signal generated by the transmission processing unit 212 is transmitted from the antenna 213.

[0054] The storage unit 22 is a storage device capable of reading and writing data, such as a DRAM, an SRAM, a flash memory, or a hard disk. The storage unit 22 functions as a storage means of the non-terrestrial station 20. The storage unit 22 stores switching information. The switching information is information used by the communication device 50 to switch between base stations. The switching information includes, for example, resource information, trigger information, timing advance information, and other information.

[0055] The resource information is information on wireless resources used by the currently connected communication device 50 for wireless communication with a switching destination candidate base station configured to be movable. The trigger information is information used by the communication device 50 to determine whether or not to switch the connection destination base station. The timing advance information is information on a timing advance for the communication device 50 to connect to the switching destination candidate base station. The resource information, trigger information, and timing advance information will be described in detail later.

[0056] The control unit 23 is a controller that controls each part of the non-terrestrial station 20. The control unit 23 is realized by a processor such as a central processing unit (CPU) or a micro processing unit (MPU). For example, the control unit 23 is realized by a processor executing various programs stored in a storage device inside the non-terrestrial station 20 using a random access memory (RAM) or the like as a working area. The control unit 23 may be realized by an integrated circuit such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). The CPU, MPU, ASIC, and FPGA can all be considered as controllers.

[0057] [Ground Station] Next, the configuration of the ground station 30 will be described. Fig. 7 is a diagram showing an example of the configuration of the ground station 30 according to the embodiment of the present disclosure. The ground station 30 includes a wireless communication unit 31, a storage unit 32, a network communication unit 33, and a control unit 34. Note that the configuration shown in Fig. 7 is a functional configuration, and the hardware configuration may be different from this. Furthermore, the functions of the ground station 30 may be distributed and implemented in multiple physically separated configurations.

[0058] The wireless communication unit 31 is a wireless communication interface that wirelessly communicates with other wireless communication devices (e.g., communication device 50). The wireless communication unit 31 includes a reception processing unit 311, a transmission processing unit 312, and an antenna 313. The configurations of the wireless communication unit 31, the reception processing unit 311, the transmission processing unit 312, and the antenna 313 are similar to those of the wireless communication unit 21, the reception processing unit 211, the transmission processing unit 212, and the antenna 213 of the non-terrestrial station 20.

[0059] The storage unit 32 is a data readable / writable storage device such as a DRAM, an SRAM, a flash memory, a hard disk, etc. The storage unit 32 functions as a storage means of the ground station 30. The configuration of the storage unit 32 is similar to that of the storage unit 22 of the non-ground station 20.

[0060] The network communication unit 33 is a communication interface for communicating with other devices. For example, the network communication unit 33 is a LAN interface such as a NIC. The network communication unit 33 may be a wired interface or a wireless interface. The network communication unit 33 functions as a network communication means of the ground station 30. The network communication unit 33 communicates with the management device 10 and the relay station 60 according to the control of the control unit 34.

[0061] The control unit 34 is a controller that controls each unit of the ground station 30. The configuration of the control unit 34 is similar to that of the control unit 23 of the non-ground station 20.

[0062] <2-4. Relay station configuration> Next, the configuration of the relay station 40 will be described. Fig. 8 is a diagram showing an example of the configuration of the relay station 40 according to the embodiment of the present disclosure. The relay station 40 includes a wireless communication unit 41, a storage unit 42, a network communication unit 43, and a control unit 44. Note that the configuration shown in Fig. 8 is a functional configuration, and the hardware configuration may be different from this. Also, the functions of the relay station 40 may be distributed and implemented in multiple physically separated configurations.

[0063] The wireless communication unit 41 is a wireless communication interface that wirelessly communicates with other wireless communication devices (for example, the non-terrestrial station 20, the terrestrial station 30, and the communication device 50). The wireless communication unit 41 includes a reception processing unit 411, a transmission processing unit 412, and an antenna 413. The configurations of the wireless communication unit 41, the reception processing unit 411, the transmission processing unit 412, and the antenna 413 are similar to those of the wireless communication unit 21, the reception processing unit 211, the transmission processing unit 212, and the antenna 213 of the non-terrestrial station 20.

[0064] The storage unit 42 is a data readable / writable storage device such as a DRAM, an SRAM, a flash memory, a hard disk, etc. The storage unit 42 functions as a storage means of the relay station 40. The configuration of the storage unit 42 is similar to that of the storage unit 22 of the non-terrestrial station 20.

[0065] The network communication unit 43 is a communication interface for communicating with other devices. For example, the network communication unit 43 is a LAN interface such as a NIC. The network communication unit 43 may be a wired interface or a wireless interface. The network communication unit 43 functions as a network communication means of the relay station 40. The network communication unit 43 communicates with the non-terrestrial station 20 and the terrestrial station 30 according to the control of the control unit 44.

[0066] The control unit 44 is a controller that controls each unit of the relay station 40. The configuration of the control unit 44 is similar to that of the control unit 23 of the non-terrestrial station 20.

[0067] <2-5. Configuration of communication device> Next, the configuration of the communication device 50 will be described. Fig. 9 is a diagram showing an example of the configuration of the communication device 50 according to the embodiment of the present disclosure. The communication device 50 includes a wireless communication unit 51, a storage unit 52, a network communication unit 53, an input / output unit 54, and a control unit 55. Note that the configuration shown in Fig. 9 is a functional configuration, and the hardware configuration may be different from this. In addition, the functions of the communication device 50 may be distributed and implemented in multiple physically separated configurations.

[0068] The wireless communication unit 51 is a wireless communication interface that wirelessly communicates with other wireless communication devices (for example, the non-terrestrial station 20, the terrestrial station 30, and the relay station 40). The wireless communication unit 51 supports one or more wireless access methods. For example, the wireless communication unit 51 supports both NR and LTE. The wireless communication unit 51 may support W-CDMA and cdma2000 in addition to NR and LTE. The wireless communication unit 51 includes a reception processing unit 511, a transmission processing unit 512, and an antenna 513. The wireless communication unit 51 may include a plurality of reception processing units 511, a transmission processing unit 512, and an antenna 513. When the wireless communication unit 51 supports a plurality of wireless access methods, each unit of the wireless communication unit 51 may be configured separately for each wireless access method. For example, the reception processing unit 511 and the transmission processing unit 512 may be configured separately for LTE and NR.

[0069] The reception processing unit 511 processes a downlink signal received via the antenna 513. The reception processing unit 511 includes a radio reception unit 511a, a demultiplexing unit 511b, a demodulation unit 511c, and a decoding unit 511d.

[0070] The wireless receiver 511a performs down-conversion, removal of unnecessary frequency components, control of amplification level, orthogonal demodulation, conversion to digital signal, removal of guard interval, extraction of frequency domain signal by fast Fourier transform, etc., on the downlink signal. The demultiplexer 511b separates the downlink channel, the downlink synchronization signal, and the downlink reference signal from the signal output from the wireless receiver 511a. The downlink channel is, for example, a channel such as PBCH (Physical Broadcast Channel), PDSCH (Physical Downlink Shared Channel), or PDCCH (Physical Downlink Control Channel). The demodulator 211c demodulates the received signal using a modulation method such as BPSK, QPSK, 16QAM, 64QAM, or 256QAM for the modulation symbols of the downlink channel. The decoder 511d performs decoding processing on the coded bits of the demodulated downlink channel. The decoded downlink data and downlink control information are output to the controller 23.

[0071] The transmission processing unit 512 performs a transmission process of the uplink control information and the uplink data, and includes an encoding unit 512a, a modulation unit 512b, a multiplexing unit 512c, and a radio transmission unit 512d.

[0072] The coding unit 512a codes the uplink control information and uplink data input from the control unit 55 using a coding method such as block coding, convolution coding, turbo coding, etc. The modulation unit 512b modulates the coded bits output from the coding unit 512a using a predetermined modulation method such as BPSK, QPSK, 16QAM, 64QAM, 256QAM, etc. The multiplexing unit 512c multiplexes the modulation symbols of each channel and the uplink reference signal, and places them in a predetermined resource element. The wireless transmission unit 512d performs various signal processing on the signal from the multiplexing unit 512c. For example, the wireless transmission unit 512d performs processing such as conversion to the time domain by inverse fast Fourier transform, addition of a guard interval, generation of a baseband digital signal, conversion to an analog signal, quadrature modulation, up-conversion, removal of unnecessary frequency components, and power amplification. The signal generated by the transmission processing unit 512 is transmitted from the antenna 513.

[0073] The storage unit 52 is a storage device capable of reading and writing data, such as a DRAM, an SRAM, a flash memory, or a hard disk. The storage unit 52 functions as a storage means of the communication device 50. The storage unit 52 stores switching information. The switching information is information acquired from the non-terrestrial station 20, the terrestrial station 30, or the relay station 40, and is used by the communication device 50 to switch between base stations. The switching information includes, for example, resource information, trigger information, timing advance information, and other information. The resource information, trigger information, and timing advance information will be described in detail later.

[0074] The network communication unit 53 is a communication interface for communicating with other devices. For example, the network communication unit 53 is a LAN interface such as a NIC. The network communication unit 53 may be a wired interface or a wireless interface. The network communication unit 53 functions as a network communication means of the communication device 50. The network communication unit 53 communicates with other devices under the control of the control unit 55.

[0075] The input / output unit 54 is a user interface for exchanging information with the user. For example, the input / output unit 54 is an operation device such as a keyboard, a mouse, an operation key, or a touch panel that allows the user to perform various operations. Alternatively, the input / output unit 54 is a display device such as a liquid crystal display (LCD) or an organic electroluminescence display (OLED). The input / output unit 54 may be an audio device such as a speaker or a buzzer. The input / output unit 54 may also be a lighting device such as an LED (Light Emitting Diode) lamp. The input / output unit 54 functions as an input / output means (input means, output means, operation means, or notification means) of the communication device 50.

[0076] The control unit 55 is a controller that controls each unit of the communication device 50. The control unit 55 is realized by a processor such as a CPU or an MPU. For example, the control unit 55 is realized by the processor executing various programs stored in a storage device inside the communication device 50 using a RAM or the like as a working area. The control unit 55 may be realized by an integrated circuit such as an ASIC or an FPGA. The CPU, the MPU, the ASIC, and the FPGA can all be considered as controllers.

[0077] <2-6. Initial connection process> Next, a description will be given of the operation of the communication system 1. First, a description will be given of an initial connection process. The initial connection is a process for transitioning from a state in which the communication device 50 is not connected to any cell (idle state) to a state in which a connection with any cell is established (connected state).

[0078] Fig. 10 is a flowchart showing an example of the initial connection process according to the present disclosure. The initial connection process will be described below with reference to Fig. 10. The initial connection process shown below is executed by the control unit 55 of the communication device 50 when the communication device 50 is powered on, for example.

[0079] As shown in Fig. 10, first, a communication device 50 in an idle state performs a cell selection procedure. The cell selection procedure includes the steps of detecting a synchronization signal and decoding a PBCH (Physical Broadcast Channel). The communication device 50 detects the synchronization signal (step S101), and performs downlink synchronization with the cell based on the detected synchronization signal.

[0080] Next, after downlink synchronization is established, the communication device 50 attempts to decode the PBCH (step S102) and acquires system information (step S103). At this time, the communication device 50 first acquires first system information, and then acquires second system information based on the first system information included in the PBCH.

[0081] Next, the communication device 50 performs a random access procedure (RACH procedure) based on the first system information and / or the second system information. The random access procedure includes the steps of transmitting a random access preamble, receiving a random access response, transmitting a message 3, and receiving contention resolution.

[0082] In the random access procedure, the communication device 50 first selects and transmits a predetermined PRACH (Physical Random Access Channel) preamble (step S104). Next, the communication device 50 receives a PDSCH (Physical Downlink Shared Channel) including a random access response corresponding to the PRACH preamble (step S105).

[0083] Next, the communication device 50 transmits a PUSCH including the message 3 using resources scheduled by the random access response grant included in the random access response (step S106). Finally, the communication device 50 receives a PDSCH including a collision resolution corresponding to the PUSCH (step S107).

[0084] Message 3 includes an RRC (Radio Resource Control) message of an RRC connection request. Collision resolution includes an RRC message of an RRC connection setup. When the communication device 50 receives the RRC message of an RRC connection setup, the communication device 50 performs an RRC connection operation and transitions from an RRC idle state to an RRC connected state. After transitioning to the RRC connected state, the communication device 50 transmits an RRC message of an RRC connection setup completion to the base station device. Through this series of operations, the communication device 50 can connect to the base station device.

[0085] The random access preamble is also called message 1, the random access response is also called message 2, the collision resolution is also called message 4, and the RRC connection setup completion message is also called message 5. After all steps of the random access procedure are completed, the communication device 50 can transition to a state in which it is connected to the cell (connected state).

[0086] The random access procedure shown in Fig. 10 is also called a four-step RACH procedure. On the other hand, a random access procedure in which the communication device 50 transmits a random access preamble and also transmits a message 3, and the base station device transmits a random access response and a contention resolution as responses to the messages, is called a two-step RACH procedure. The two-step RACH procedure will be described later with reference to Fig. 13.

[0087] The random access preamble is transmitted in association with the PRACH. The random access response is transmitted on the PDSCH. The PDSCH including the random access response is scheduled on the PDCCH (Physical Downlink Control Channel). Message 3 is transmitted on the PUSCH. The PUSCH including the message 3 is scheduled by the uplink grant included in the random access response.

[0088] [System Information] Next, system information according to the present disclosure will be described. The system information is information that reports the settings in the cell that transmits the system information. The system information includes, for example, information on access to the cell, information on cell selection, information on other RATs (Radio Access Technologies) and other systems, and the like.

[0089] System information can be classified into MIB (Master Information Block) and SIB (System Information Block). MIB is information of a fixed payload size broadcast by PBCH. MIB includes information for acquiring SIB. SIB is system information other than MIB. SIB is broadcast by PDSCH.

[0090] Moreover, 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 on access to the cell, information on acquisition of other system information, and information on cell selection. The information included in the MIB can be considered as the first system information, and the information included in the SIB1 as the second system information. If the communication device 50 cannot acquire the first system information from the cell, it assumes that access to the cell is prohibited.

[0091] The MIB is physical layer information required to receive system information, and includes a portion of the system frame number, at least SIB1 and Msg.2 / 4 for initial connection and subcarrier spacing information for paging and broadcast SI messages, subcarrier offset information, DMRS type A location information, PDCCH setting for at least SIB1, cell barred information, intra-frequency reselection information, etc.

[0092] SIB1 includes information on cell selection, information related to cell access, information on connection establishment failure control, scheduling information of system information other than SIB1, serving cell configuration, etc. The serving cell configuration includes cell-specific parameters, and includes downlink configuration, uplink configuration, TDD configuration information, etc. The uplink configuration includes RACH configuration, etc.

[0093] [RACH Procedure] Next, a RACH procedure according to the present disclosure will be described. The RACH procedure is performed to achieve purposes such as RRC connection setup from an idle state to an inactive state or a connected state, a request for state transition from an inactive state to a connected state, and handover to switch a connected cell.

[0094] The RACH procedure is also used to achieve the following purposes: a scheduling request to request resources for uplink data transmission, a timing advance adjustment to adjust uplink synchronization, etc. The RACH procedure is also used to achieve the following purposes: an on-demand SI request to request system information that has not been transmitted, and recovery of a broken beam connection (beam recovery).

[0095] The RRC connection setup from an idle state to an inactive state or a connected state is an operation performed when the communication device 50 connects to the base station device in response to traffic generation, etc. Specifically, it is an operation of passing information related to the connection (e.g., UE context) from the base station device to the communication device 50.

[0096] The UE context is managed by a predetermined communication device identification information (e.g., C-RNTI) instructed by the base station device. After completing this operation, the communication device 50 transitions from the idle state to the inactive state, or from the idle state to the connected state.

[0097] The request for state transition from the inactive state to the connected state is an operation for requesting state transition from the inactive state to the connected state in response to traffic generation, etc. By transitioning to the connected state, the communication device 50 can transmit and receive unicast data to and from the base station device.

[0098] Handover, which switches a connection cell, is an operation for switching a connection from a connected cell (serving cell) to a cell adjacent to the connected cell (neighbor cell) due to a change in the radio wave environment, such as the movement of the communication device 50. The communication device 50 that receives a handover command from the base station device makes a connection request to the neighbor cell specified by the handover command.

[0099] A scheduling request is an operation for requesting resources for uplink data transmission in response to traffic generation, etc. After successfully receiving this scheduling request, the base station apparatus allocates PUSCH resources to the communication apparatus 50. Note that a scheduling request is also made by PUCCH.

[0100] Timing advance adjustment, which adjusts uplink synchronization, is an operation for adjusting the error between downlink and uplink frames caused by propagation delay. The communication device 50 transmits the PRACH at the timing adjusted to the downlink frame. This allows the base station device to recognize the propagation delay with the communication device 50, and to instruct the communication device 50 on the value of the timing advance using a message 2 or the like.

[0101] An on-demand SI request for untransmitted system information is an operation for requesting a base station device to transmit system information when system information that has not been transmitted due to system information overhead or the like is required by communication device 50.

[0102] Restoring a broken beam connection (beam recovery) is an operation to request restoration when communication quality deteriorates after a beam is established due to movement of the communication device 50 or interruption of the communication path by other objects, etc. The base station device that receives this request attempts to connect to the communication device 50 using a different beam.

[0103] The RACH procedure further includes a collision-based RACH procedure and a non-collision RACH procedure, which will be described below.

[0104] [Collision-based RACH procedure] 11 is a sequence diagram showing a collision-based RACH procedure according to the present disclosure. The collision-based RACH procedure is a RACH procedure initiated by the communication device 50. The collision-based RACH procedure is a four-step procedure starting with the transmission of a message 1 from the communication device 50.

[0105] The communication device 50 selects from a plurality of preset RACH resources and a plurality of preset PRACH preambles and transmits the PRACH. Since the plurality of RACH resources and the plurality of preset PRACH preambles are shared with other communication devices 50, the PRACHs may collide.

[0106] The collision-based RACH procedure includes the steps of transmitting a random access preamble (Msg1), receiving a random access response (Msg2), transmitting a message (Msg3), and receiving a contention resolution message (Msg4).

[0107] As shown in Fig. 11, in the collision-based RACH procedure, first, the control unit 55 in the communication device 50 randomly selects a preamble sequence to be used from a plurality of predefined preamble sequences. Then, the control unit 55 transmits a message (Msg1: Random Access Preamble) including the selected preamble sequence to the destination base station (step S201). At this time, the base station may be the non-terrestrial station 20 or the terrestrial station 30. In the following description, it is assumed that the base station to which the control unit 55 transmits the random access preamble is the non-terrestrial station 20. The random access preamble is transmitted by the PRACH.

[0108] When the control unit 23 of the non-terrestrial station 20 receives the random access preamble, it transmits a random access response (Msg2: Random Access Response) to the communication device 50. This random access response is transmitted, for example, using PDSCH. The control unit 55 in the communication device 50 receives the random access response (Msg2) transmitted from the base station (step S202). The random access response includes one or more random access preambles that the base station has been able to receive, and UL (Up Link) resources (hereinafter referred to as uplink grants) corresponding to the random access preambles. The random access response also includes a TC-RNTI (Temporary Cell Radio Network Temporary Identifier) ​​that is an identifier unique to the communication device 50 and temporarily assigned to the communication device 50 by the base station.

[0109] When the control unit 55 of the communication device 50 receives a random access response from the base station, the control unit 55 determines whether or not the random access preamble transmitted in step S201 is included in the received information. If the random access preamble is included, the control unit 55 extracts an uplink grant corresponding to the random access preamble transmitted in step S201 from the uplink grants included in the random access response. Then, the control unit 55 transmits a UL message (Msg3: Scheduled Transmission) using resources scheduled by the extracted uplink grant (step S203). The message (Msg3) is transmitted using the PUSCH. The message (Msg3) includes an RRC message for an RRC (Radio Resource Control) connection request. The message (Msg3) also includes an identifier of the communication device 50.

[0110] In the collision-based RACH procedure, a random access preamble randomly selected by the communication device 50 is used in the procedure. Therefore, a case may occur where the communication device 50 transmits a random access preamble and another communication device 50 transmits the same random access preamble to the non-terrestrial station 20 at the same time. In this case, the control unit 23 of the non-terrestrial station 20 recognizes which communication device 50 has generated a preamble conflict between them by receiving the identifier transmitted by the communication device 50 in step S203, and resolves the conflict. The control unit 23 transmits a contention resolution (Msg4: Contention Resolution) to the communication device 50 selected by the contention resolution. The contention resolution (Msg4) includes the identifier transmitted by the control unit 55 in step S203. The contention resolution (Msg4) also includes an RRC message for RRC connection setup. The control unit 55 receives the contention resolution message (Msg4) transmitted from the base station (step S204).

[0111] [Non-collision based RACH procedure] FIG. 12 is a sequence diagram showing a non-contention based RACH procedure according to the present disclosure. The non-contention RACH procedure is a RACH procedure initiated by a base station. The non-contention RACH procedure is a procedure of a total of three steps starting from the transmission of a PDCCH order from the base station device. The communication device 50 transmits the PRACH using a PRACH preamble indicated in the PDCCH order. The base station device schedules the PRACH preamble, making it difficult for the PRACH to collide.

[0112] The non-collision RACH procedure includes the steps of receiving a random access preamble allocation (Msg0), transmitting a random access preamble (Msg1), and receiving a random access response (Msg2). In the following description of the random access procedure, the base station is assumed to be a non-terrestrial station 20, but the base station may be a terrestrial station 30.

[0113] In the contention RACH procedure, the control unit 55 of the communication device 50 randomly selects a preamble sequence. However, in the non-contention RACH procedure, the non-earth station 20 assigns an individual random access preamble to the communication device 50. The control unit 55 of the communication device 50 receives an assignment of a random access preamble (Msg0: RA Preamble Assignment) from the non-earth station 20 (step S301).

[0114] The control unit 55 of the communication device 50 uses the random access preamble allocated in step S301 to execute random access to the non-terrestrial station 20. That is, the control unit 55 of the communication device 50 transmits the allocated random access preamble (Msg1: Random Access Preamble) to the non-terrestrial station 20 by PRACH (step S302).

[0115] The control unit 23 of the non-terrestrial station 20 receives a random access preamble (Msg1) from the communication device 50. Then, the control unit 23 transmits a random access response (Msg2: Random Access Response) in response to the random access preamble to the communication device 50 (step S303). The random access response includes, for example, information on an uplink grant corresponding to the received random access preamble. Upon receiving the random access response (Msg2), the control unit 55 of the communication device 50 performs an RRC connection operation and transitions from an idle state (RRC_IDLE) to a connected state (RRC_CONNECTED).

[0116] [NR PRACH details] NR-PRACH is configured using a Zadoff-Chu sequence. Multiple preamble formats are specified for NR-PRACH. The preamble format is specified 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, CP length, and guard period length.

[0117] For the communication device 50 in idle mode, settings related to the NR-PRACH are made by the system information. Furthermore, for the terminal device in connected mode, settings related to the NR-PRACH are made by dedicated RRC signaling.

[0118] The NR-PRACH is transmitted by physical resources (NR-PRACH occasions) on which the NR-PRACH can be transmitted. The physical resources are specified by the configuration related to the NR-PRACH. The communication device 50 selects one of the physical resources to transmit the NR-PRACH.

[0119] Furthermore, the communication device 50 in the connected mode transmits the NR-PRACH using the NR-PRACH resource. The NR-PRACH resource is a combination of the NR-PRACH preamble and its physical resource. The base station device can indicate the NR-PRACH resource to the terminal device.

[0120] The type of the preamble sequence of the NR-PRACH is numbered. The number of the type of the preamble sequence is called a preamble index. The NR-PRACH is retransmitted when the random access procedure fails.

[0121] When retransmitting, the communication device 50 waits for the transmission of the NR-PRACH for a waiting period calculated from a backoff value (backoff indicator, BI). Note that the backoff value may differ depending on the terminal category of the terminal device and the priority of the generated traffic.

[0122] At this time, multiple backoff values ​​are notified, and communication device 50 selects the backoff value to be used based on the priority. Also, when retransmitting NR-PRACH, the transmission power of NR-PRACH is increased compared to the initial transmission (this procedure is called power ramping).

[0123] [NR Random Access Response Details] The NR random access response is sent by the NR-PDSCH. The NR-PDSCH containing the random access response is scheduled by the NR-PDCCH whose CRC is scrambled by the RA-RNTI. The NR-PDCCH is transmitted on the common control subband. The NR-PDCCH is placed in the common search space (CSS).

[0124] The value of the RA-RNTI is determined based on the transmission resources (time resources (slots or subframes) and frequency resources (resource blocks)) of the NR-PRACH corresponding to the random access response. The NR-PDCCH may be placed in a search space associated with the NR-PRACH associated with the random access response.

[0125] Specifically, the search space in which the NR-PDCCH is arranged is associated with the preamble of the NR-PRACH and / or the physical resource in which the NR-PRACH is transmitted, and is set. The search space in which the NR-PDCCH is arranged is associated with the preamble index and / or the physical resource index, and is set. The NR-PDCCH is the NR-SS and the QCL.

[0126] The NR random access response is MAC information. The NR random access response includes at least an uplink grant for transmitting NR message 3, a timing advance value used to adjust uplink frame synchronization, and a temporary C-RNTI value.

[0127] The NR random access response also includes the PRACH index used for the NR-PRACH transmission corresponding to the random access response. The NR random access response also includes information on the backoff used to wait for the PRACH transmission. The base station device transmits the NR-PDSCH including these pieces of information.

[0128] The communication device 50 judges whether the transmission of the random access preamble is successful or not based on this information. If the communication device 50 judges based on this information that the transmission of the random access preamble has failed, the communication device 50 performs a transmission process of the NR message 3 according to the information included in the random access response. On the other hand, if the communication device 50 judges that the transmission of the random access preamble has failed, the communication device 50 considers that the random access procedure has failed, and performs a retransmission process of the NR-PRACH.

[0129] The NR random access response may include a plurality of uplink grants for transmitting the NR message 3. The communication device 50 can select one resource for transmitting the message 3 from the plurality of uplink grants. This can mitigate collisions of NR message 3 transmissions when different communication devices 50 receive the same NR random access response, and can provide a more stable random access procedure.

[0130] [Details of NR message 3] NR message 3 is sent by NR-PUSCH. The NR-PUSCH is transmitted using resources indicated by the random access response. NR message 3 includes an RRC connection request message.

[0131] The waveform of the NR-PUSCH transmitted including the NR message 3 is specified by a parameter included in the system information. Specifically, OFDM or DFT-s-OFDM is determined by the parameter.

[0132] When the base station device has normally received the NR message 3, the base station device proceeds to a transmission process for collision resolution. On the other hand, when the base station device has not normally received the NR message 3, the base station device can attempt to receive the NR message 3 again for at least a predetermined period of time.

[0133] Another example of the instruction and transmission resource for retransmission of message 3 is an instruction by NR-PDCCH used for instructing retransmission of message 3. The NR-PDCCH is an uplink grant. The DCI of the NR-PDCCH instructs the resource for retransmission of message 3. Communication device 50 retransmits message 3 based on the instruction of the uplink grant.

[0134] Furthermore, if the communication device 50 does not successfully receive the NR collision resolution within a predetermined period, it considers the random access procedure to have failed and performs a retransmission process of the NR-PRACH. Note that the transmission beam of the communication device 50 used to retransmit the NR message 3 may be different from the transmission beam of the communication device 50 used to initially transmit the message 3.

[0135] Furthermore, if the communication device 50 does not receive either the NR collision resolution or the instruction to retransmit the message 3 within a predetermined period of time, the communication device 50 considers the random access procedure to have failed, and performs the retransmission process of the NR-PRACH. The predetermined period of time is set, for example, by the system information.

[0136] [Details on NR conflict resolution] NR collision resolution is sent by NR-PDSCH. The NR-PDSCH including collision resolution is scheduled by a temporary C-RNTI or an NR-PDCCH with CRC scrambled by the C-RNTI. The NR-PDCCH is placed in a USS (terminal specific search space). The NR-PDCCH may be placed in a CSS.

[0137] When the communication device 50 normally receives the NR-PDSCH including the collision resolution, it responds with an ACK to the base station device. After that, it is considered that this random access procedure is successful, and the communication device 50 is in a connected state. On the other hand, when the base station device receives a NACK for the NR-PDSCH including the collision resolution from the communication device 50, or there is no response, it retransmits the NR-PDSCH including the collision resolution. Furthermore, when the communication device 50 does not receive the NR collision resolution within a predetermined period, it considers that the random access procedure has failed, and performs a retransmission process of the NR-PRACH.

[0138] [NR 2-STEP RACH] Next, the NR 2-STEP RACH will be described. Fig. 13 is a sequence diagram showing the NR 2-STEP RACH according to the present disclosure. The 2-STEP RACH procedure is composed of 2 steps, Message.A (step S401) and Message.B (step S402).

[0139] FIG. 13 shows, as an example, a case where Message.A includes Message.1 (Preamble) and Message.3 of the conventional 4-STEP RACH, and Message.B includes Message.2 and Message.4 of the conventional 4-STEP RACH.

[0140] As an example, Message.A is composed of a PRACH (Preamble) and a PUSCH, and Message.B is composed of a PDSCH. The 2-step random access procedure makes it possible to complete the random access procedure with less delay than the conventional 4-step random access procedure.

[0141] The preamble and PUSCH included in Message.A may be set with their respective transmission resources linked together, or may be set with independent resources. When the transmission resources are set with their respective transmission resources linked together, for example, when the transmission resource of the preamble is determined, the transmission resource of the PUSCH, which may be a unique or multiple candidate, is determined.

[0142] As an example, the time and frequency offset between the preamble of the PRACH occasion and the PUSCH occasion is determined to be a single value, or as another example, the time and frequency offset between the preamble of the PRACH occasion and the PUSCH occasion is determined to be a different value for each preamble.

[0143] The offset value may be determined by the specifications, or may be set semi-statically by the base station device. An example of the time and frequency offset values ​​is defined by a predetermined frequency. For example, in an unlicensed band (5 GHz band, band 45), the time offset value can be set to 0 or a value close to 0.

[0144] This makes it possible to omit LBT (Listen Before Talk) before transmitting PUSCH. On the other hand, when the preamble and PUSCH are set as independent resources, the transmission resources of the preamble and PUSCH may be determined by the specification, the base station device may set the resources semi-statically, or the resources may be determined from other information.

[0145] Examples of the other information include slot format information (such as a slot format indicator), Band Width Part (BWP) information, preamble transmission resource information, a slot index, and a resource block index.

[0146] Furthermore, when configured with independent resources, the association between the preamble and PUSCH constituting one Message.A may be notified to the base station by the payload of the PUSCH or UCI included in the PUSCH. Furthermore, the association between the preamble and PUSCH constituting one Message.A may be notified to the base station by the transmission physical parameters of the PUSCH (for example, the scrambling sequence of the PUSCH, the DMRS sequence and / or pattern, and the transmission antenna port of the PUSCH).

[0147] In addition, the method of setting the transmission resources of the preamble and the PUSCH may be switched between a case where they are set in association with each other and a case where they are set in independent resources. For example, the case where they are set in independent resources may be applied in the licensed band, and the case where the transmission resources are set in association with each other may be applied in the unlicensed band.

[0148] Here, when the base station device is a satellite station, the propagation delay becomes very large compared to a terrestrial network because the radio wave propagation distance is long. The propagation delay is approximately 41.75 ms round trip for a low-orbit satellite and 541.14 ms round trip for a geostationary satellite. Due to this propagation delay, it is considered that a problem occurs in the PRACH transmission and reception at the time of initial access in the communication system 1.

[0149] One of the purposes of PRACH transmission and reception is to calculate the propagation delay between the base station device and the communication device 50 and to achieve uplink synchronization. If the propagation delay is large, the base station device may receive the transmitted PRACH significantly beyond the expected PRACH receiving slot.

[0150] In this case, the base station device may not know which PRACH reception timing is shifted from. Figure 14 is an explanatory diagram of a problem caused by a propagation delay according to the present disclosure. DL shown in Figure 14 is a downlink slot used for transmitting and receiving a synchronization signal. UL is an uplink slot used for transmitting and receiving a PRACH.

[0151] Moreover, SSB1 and SSB2 shown in Fig. 14 are synchronization signals transmitted from the base station device. The synchronization signal here refers to an SS (Synchronization Signal), an SS Block having one or more SSs, and an SS Block Set having one or more SS Blocks, all of which are transmitted from the base station device.

[0152] The synchronization signal also includes a PBCH (Physical Broadcast Channel) that transmits the MIB and SIB. The synchronization signal also includes signals that can be reference signals other than the above. The SS block may be called an SS / PBCH block.

[0153] The above synchronization signals are transmitted one or more times from the base station device. Here, "multiple" includes synchronization signals having different characteristics or the same characteristics. Examples of the characteristics of the synchronization signals include different resources, different sequences, different beams, different reference signal ports, and the like.

[0154] Moreover, PRACH (SSB1) shown in FIG. 14 is an uplink slot on the base station device side in which the PRACH transmitted from the communication device 50 that received SSB1 is expected to be stored if there is no propagation delay.

[0155] The communication device 50 transmits the PRACH to the base station device by using the PRACH resource. The PRACH resource is a resource that the communication device 50 can transmit the PRACH. The PRACH resource may be set in association with a synchronization signal, or may be set independently of the PRACH resource. The PRACH here corresponds to the Random Access Preamble transmitted in step S201 shown in FIG. 11.

[0156] Moreover, PRACH(SSB2) is an uplink slot on the base station device side in which PRACH transmitted from communication device 50 that has received SSB2 is expected to be stored if there is no propagation delay.

[0157] When there is no propagation delay, the communication device 50 receives SSB1 at substantially the same time as the base station device transmits SSB1, and transmits a PRACH to the base station device after a predetermined time (e.g., three slots after receiving SSB1). Therefore, when there is no propagation delay, the base station device stores the PRACH corresponding to SSB1 in PRACH(SSB1) shown in FIG.

[0158] 14, for example, a one-way propagation delay of three slots may occur from the time when the base station device transmits SSB1 until the communication device 50 receives SSB1. In such a case, when the communication device 50 transmits a PRACH to the base station device a predetermined time after the reception of SSB1 (for example, three slots after the reception of SSB1), a propagation delay also occurs here, and the base station device receives the PRACH in the sixth slot after the PRACH (SSB1).

[0159] At this time, if the base station device transmits SSB1 and SSB2 alternately, the base station device may receive the PRACH corresponding to SSB2, which was transmitted before SSB1 shown in FIG. 14, via PRACH(SS2B).

[0160] In such a case, the deviation between PRACH(SSB1), which is the original reception timing of the PRACH corresponding to SSB1 shown in FIG. 14, and PRACH reception, which is the timing when the PRACH is actually received, is the actual reception timing deviation (1) shown in the same figure.

[0161] However, the base station device may mistakenly determine that the PRACH received this time is the PRACH corresponding to SSB2, and may mistake the deviation (2) shown in the figure, which is the time from the PRACH (SSB2) to the reception of the PRACH, as a deviation in the reception timing due to propagation delay.

[0162] In addition, in the case of TDD or when the half-duplex problem exists (when the base station device cannot operate DL and UL simultaneously), if the reception timing deviates significantly from the original reception timing, the base station device may not be able to receive the PRACH.

[0163] For this reason, in the communication system 1, when the propagation delay is large and the reception timing of the PRACH exceeds the expected slot, a means is required for the base station device to receive the PRACH and correctly calculate the amount of propagation delay. Therefore, in this disclosure, the following first to third communication methods are proposed as measures for the case where the propagation delay is large.

[0164] <2-7. First communication method> Fig. 15 is a sequence diagram showing a first communication method according to the present disclosure. As shown in Fig. 15, a base station device (for example, the transmission processing unit 212 of the non-terrestrial station 20) transmits a synchronization signal (step S501) and transmits a PRACH configuration (step S502).

[0165] When the communication device 50 receives a synchronization signal by the reception processing unit 511 (receiving unit), the control unit 55 functions as a generating unit that generates a PRACH, and generates a PRACH including a feature that can uniquely identify the synchronization signal and / or the PRACH resource (step S503).

[0166] In this case, the uniquely identifiable feature refers to a feature that, when the base station device receives a PRACH from the communication device 50, can uniquely identify which PRACH corresponds to which previously transmitted synchronization signal the received PRACH corresponds to.

[0167] The uniquely identifiable features include, for example, at least one of a resource, a sequence, and a reference signal port that are different for each synchronization signal, and at least one of a preamble sequence, a demodulation reference signal (DMRS) sequence, a scrambling sequence, an interleaving sequence, and a message that are different for each PRACH.

[0168] The transmission processing unit 512 (transmission unit) of the communication device 50 transmits the PRACH generated by the generation unit to the base station device (step S504). Specifically, the communication device 50 transmits the PRACH by the above-mentioned source, sequence, or the like that allows the base station device to uniquely identify the corresponding synchronization signal and / or PRACH resource. The base station device (for example, the reception processing unit 211 of the non-terrestrial station 20) receives the PRACH from the communication device 50 that has received the synchronization signal, beyond the expected reception resource.

[0169] At this time, the base station device receives a PRACH including a feature that can uniquely identify a synchronization signal and / or a PRACH resource, and thus the base station device can estimate which synchronization signal or PRACH resource the PRACH corresponds to based on the received PRACH (step S505).

[0170] Then, the control unit of the base station device (for example, the control unit 23 of the non-terrestrial station 20) functions as a calculation unit that calculates the propagation delay of the synchronization signal and the PRACH, and calculates the propagation delay. At this time, the control unit of the base station device calculates and estimates the propagation delay based on, for example, the transmission timing of the synchronization signal and the reception timing of the PRACH (step S506). After that, the base station device transmits a Timing advance command to the communication device 50 that transmitted the PRACH (step S507).

[0171] In this way, in the first communication method, the communication device 50 transmits a PRACH including a feature capable of uniquely identifying a synchronization signal and / or a PRACH resource to the base station device. Therefore, the base station device can estimate which synchronization signal and / or PRACH resource the PRACH received from the communication device 50 corresponds to. This allows the base station device to more accurately calculate the propagation delay. Therefore, the communication system 1 can further improve the quality between wireless links.

[0172] In addition, the receiving unit of the communication device 50 may be configured to receive characteristic information indicating characteristics that can uniquely identify the synchronization signal and / or the PRACH resource from the base station device, or may be configured to receive a calculation formula, etc. that can derive the above-mentioned characteristics from the base station device.

[0173] In such a configuration, the base station device transmits the above-mentioned features and calculation formulas capable of deriving the features to the communication device 50, for example, by MIB, SIB, RRC, and signaling. This allows the communication device 50 to derive feature amounts from, for example, the SS Block index. Even with such a configuration, the communication device 50 can generate a PRACH including a feature capable of uniquely identifying a synchronization signal and / or a PRACH resource, and transmit the PRACH to the base station device.

[0174] <2-8. Second communication method> Fig. 16 is a sequence diagram showing a second communication method according to the present disclosure. As shown in Fig. 16, a base station device (for example, the transmission processing unit 212 of the non-terrestrial station 20) transmits a synchronization signal (step S601) and transmits a PRACH configuration (step S602).

[0175] Furthermore, the base station device transmits information about the "previous timing" (step S603). The "previous timing" here refers to a timing that is earlier than the transmission timing of the PRACH defined by the PRACH resource.

[0176] The base station device transmits, for example, information indicating the time from reception of a synchronization signal to start of transmission of the PRACH, or information indicating the time to start transmission of the current PRACH prior to the transmission timing of the PRACH that is originally to be transmitted, to the communication device 50. At this time, the unit of time notified from the base station device to the communication device 50 can be, for example, the number of symbols, the number of slots, the number of subframes, the number of frames, milliseconds, or the like.

[0177] The base station device can also transmit to the communication device 50 information regarding the “previous timing”, such as the base station device’s location information, moving orbit information, moving speed information, altitude information, and transmission time information of the synchronization signal transmitted from the base station device.

[0178] In the communication device 50, the control unit 55 functions as a calculation unit that calculates the “previous timing”, and calculates the “previous timing” for transmitting the PRACH based on information regarding the “previous timing” received from the base station device (step S604).

[0179] The communication device 50 calculates the "previous timing" based on at least one of the position information, movement trajectory information, movement speed information, and altitude information of the base station device and / or the communication device 50, for example.

[0180] The communication device 50 may also calculate the "previous timing" based on transmission time information of a synchronization signal transmitted from a base station device and reception time information of a synchronization signal received. The communication device 50 may also receive a formula capable of deriving the "previous timing" and derive the "previous timing" using the received formula.

[0181] In such a configuration, the base station device may transmit an index corresponding to the formula to the communication device 50. For example, the base station device transmits an index to the communication device 50, with Index #1 representing Formula #1 and Index #2 representing Formula #2.

[0182] Furthermore, the communication device 50 may receive timing information indicating the "previous timing" from the base station device. In such a configuration, the base station device calculates the "previous timing" by a method similar to the above-described method by which the communication device 50 calculates the "previous timing" and transmits it to the communication device 50.

[0183] The base station device may notify the communication device 50 of the "previous timing" or a formula capable of deriving the "previous timing" by using, for example, MIB, SIB, RRC, signaling, or the like.

[0184] The communication device 50 transmits the PRACH at an "earlier timing" than the original PRACH transmission timing (step S605). The base station device receives the PRACH, and calculates and estimates the propagation delay by adding a time offset for the "earlier timing" to the reception timing of the PRACH (step S606).

[0185] In this way, even if there is a propagation delay, the base station device can receive the PRACH at the original reception timing because the PRACH is transmitted from the communication device 50 at an "earlier timing" than the original PRACH transmission timing.

[0186] This allows the base station device to more accurately calculate the propagation delay. After that, the base station device transmits a Timing advance command to the communication device 50 that has transmitted the PRACH (step S607).

[0187] In this way, in the second communication method, the propagation delay time is estimated in advance and the PRACH transmission timing is shifted forward, so that the base station device can receive the PRACH at the original reception timing.

[0188] The control unit of the base station device (for example, the control unit 23 of the non-terrestrial station 20) can also function as a calculation unit that calculates the time offset. For example, the control unit of the base station calculates the time offset by calculating the "previous timing" in a manner similar to the manner in which the communication device 50 calculates the "previous timing".

[0189] Furthermore, the base station device can also transmit the calculated time offset to the communication device 50. In this case, the transmitting unit of the base station device (the transmission processing unit 212 of the non-terrestrial station 20) functions as a notifying unit that notifies the communication device 50 of the time offset.

[0190] <2-9. The third communication method> In the third communication method, a transmitter (e.g., a transmission processing unit 512) of the communication device 50 transmits the PRACH to the base station device using a band dedicated to the PRACH transmission or a slot dedicated to the PRACH transmission. Also, a receiver (e.g., a reception processing unit 211 of the non-terrestrial station 20) of the base station device receives the PRACH from the communication device 50 using a band dedicated to the PRACH reception or a slot dedicated to the PRACH reception.

[0191] The band dedicated to PRACH transmission is a band dedicated to the purpose of transmitting the PRACH. The band dedicated to PRACH reception is a band dedicated to the purpose of receiving the PRACH. Hereinafter, the band dedicated to PRACH transmission and the band dedicated to PRACH reception may be collectively referred to as the PRACH transmission / reception dedicated band.

[0192] The band dedicated for PRACH transmission and reception may be configured as a PRACH dedicated bandwidth part, a PRACH dedicated resource block, a PRACH dedicated component carrier, etc. Also, the band dedicated for PRACH transmission and reception may be configured as a PRACH dedicated resource block.

[0193] The slots dedicated to PRACH transmission are slots dedicated to transmitting the PRACH. The slots dedicated to PRACH reception are slots dedicated to receiving the PRACH. Hereinafter, the slots dedicated to PRACH transmission and the slots dedicated to PRACH reception may be collectively referred to as the slots dedicated to PRACH transmission and reception.

[0194] The slots dedicated to PRACH transmission and reception are slots for transmitting and receiving PRACH, for example, by combining multiple symbols, multiple slots, multiple subframes, etc. The slots dedicated to PRACH transmission and reception may be defined as a different slot format, or a combination pattern of multiple symbols, slots, and subframes may be defined.

[0195] The above-mentioned PRACH transmission / reception dedicated band and PRACH transmission / reception dedicated slot each have a boundary. Therefore, in the present disclosure, for example, the boundary of the PRACH transmission / reception dedicated band or the PRACH transmission / reception slot is set to the leading time of the SSB transmission slot.

[0196] Also, for example, the boundary of the PRACH transmission / reception dedicated band or the PRACH transmission / reception dedicated slot may be the time obtained by adding a time offset to the start time of the SSB transmission slot. The time offset is expressed by a symbol, a slot, a subframe, an absolute time amount, or the like.

[0197] Fig. 17 is an explanatory diagram of a third communication method according to the present disclosure. The UL shown in the thick rectangle in Fig. 17 is a PRACH transmission / reception dedicated band or a PRACH transmission / reception dedicated slot. In the example shown in Fig. 17, the boundary of the PRACH transmission / reception dedicated band or the PRACH transmission / reception dedicated slot is set to the start time of the SSB transmission slot. In addition, the base station device transmits two SSBs, SSB1 and SSB2, and has a PRACH transmission / reception dedicated band or a PRACH transmission / reception dedicated slot corresponding to each SSB.

[0198] The communication device 50 that has received SSB1 transmits the PRACH using the resource of the PRACH (SSB1). For example, the communication device 50 transmits the PRACH after a predetermined time T PRACH Suppose that PRACH is transmitted later. T PRACH The time may be notified in advance from the base station device as time information using an SIB or the like, or may be determined in advance as a specification.

[0199] The base station device receives the transmitted PRACH and calculates the propagation delay amount. At this time, the base station device receives the PRACH corresponding to SSB1 and stores it in the PRACH(SSB1) which is an UL slot dedicated to SSB1, and receives the PRACH corresponding to SSB2 and stores it in the PRACH(SSB2) which is an UL slot dedicated to SSB2.

[0200] Therefore, when the base station device receives a PRACH corresponding to SSB1, the base station device can prevent erroneous determination that the PRACH is a PRACH corresponding to SSB2. This allows the base station device to calculate an accurate round trip delay amount from when the synchronization signal is transmitted to when the PRACH is received.

[0201] In the example shown in FIG. 17, the round trip propagation delay can be calculated as follows: (Round trip propagation delay) = (PRACH reception start timing) - (SSB1 transmission start timing) - T PRACH

[0202] Furthermore, as described above, the base station device can set the boundary of the PRACH transmission / reception dedicated band or the PRACH transmission / reception dedicated slot to the time that is the start time of the SSB transmission slot plus a time offset.

[0203] This allows the base station device to prevent two PRACHs received with a time difference from being stored in one PRACH (SSB1), thereby enabling the base station device to calculate a more accurate round-trip delay amount from transmitting the synchronization signal to receiving the PRACH.

[0204] <2-10.Effects> The communication device includes a receiving unit and a transmitting unit. The receiving unit receives a synchronization signal transmitted from a base station device. The transmitting unit transmits a PRACH including a feature capable of uniquely identifying the synchronization signal and / or the PRACH resource received by the receiving unit to the base station device. This allows the base station device to accurately determine which transmitted synchronization signal corresponds to the received PRACH, thereby allowing the base station device to more accurately calculate the propagation delay. As a result, the communication device can further improve the quality between wireless links.

[0205] The communication device further includes a generating unit configured to generate a PRACH including the above-mentioned feature, whereby the communication device can transmit the PRACH including the feature capable of uniquely identifying the synchronization signal and / or the PRACH resource to the base station.

[0206] In addition, the above characteristics include at least one of resources, sequences, beams, and reference signal ports that are different for each synchronization signal. This allows the communication device to allow the base station device to accurately determine which synchronization signal the PRACH having the above characteristics corresponds to.

[0207] In addition, the above characteristics include at least one of a preamble sequence, a demodulation reference signal sequence, a scramble sequence, an interleave sequence, and a message that are different for each PRACH. This allows the communication device to allow the base station device to accurately determine which synchronization signal corresponds to the PRACH having the above characteristics.

[0208] In addition, the receiving unit receives characteristic information indicating characteristics from the base station device. In this way, the communication device can transmit a PRACH including the characteristics indicated by the characteristic information to the base station device, thereby allowing the base station device to reliably determine which synchronization signal corresponds to the PRACH.

[0209] The communication device further includes a calculation unit for deriving the feature. The receiving unit receives a formula for deriving the feature from the base station device. The communication device can derive a feature for uniquely identifying the synchronization signal and / or the PRACH resource by using the received formula.

[0210] In the communication method, a communication device receives a synchronization signal transmitted from a base station device, and transmits a PRACH including a feature capable of uniquely identifying the received synchronization signal and / or a PRACH resource to the base station device. This allows the base station device to accurately determine which transmitted synchronization signal corresponds to the received PRACH, thereby more accurately calculating the propagation delay. As a result, the communication device can further improve the quality between wireless links.

[0211] Moreover, the communication device includes a receiving unit and a transmitting unit. The receiving unit receives a synchronization signal transmitted from the base station device. The transmitting unit transmits the PRACH to the base station device at a timing prior to the transmission timing of the PRACH defined by the PRACH resource. This allows the base station device to receive the PRACH at the original PRACH reception timing even when there is a propagation delay, and to more accurately calculate the propagation delay. As a result, the communication device can further improve the quality between the wireless links.

[0212] The communication device also includes a calculation unit for calculating the previous timing, which allows the communication device to calculate accurate previous timing according to the propagation delay.

[0213] The calculation unit calculates the previous timing based on at least one of the location information, the movement trajectory information, the movement speed information, and the altitude information of the base station device and / or the communication device, thereby enabling the communication device to calculate the previous timing more accurately.

[0214] In addition, the calculation unit calculates the previous timing based on the transmission time information and reception time information of the synchronization signal used in wireless communication with the base station device, thereby enabling the communication device to calculate the previous timing in accordance with the actual propagation delay.

[0215] Furthermore, the receiver receives a formula for deriving the previous timing from the base station device, which allows the communication device to calculate an appropriate previous timing that differs for each base station device.

[0216] Furthermore, the receiver receives timing information indicating the previous timing from the base station device, which allows the communication device to calculate an appropriate previous timing that differs for each base station device.

[0217] In addition, in the communication method, the communication device receives a synchronization signal transmitted from the base station device, and transmits the PRACH to the base station device at a timing earlier than the transmission timing of the PRACH defined by the PRACH resource. This allows the base station device to receive the PRACH at the original PRACH reception timing even if there is a propagation delay, and to calculate the propagation delay more accurately. As a result, the communication device can further improve the quality between the wireless links.

[0218] Moreover, the communication device includes a receiving unit and a transmitting unit. The receiving unit receives a synchronization signal transmitted from the base station device. The transmitting unit transmits the PRACH to the base station device using a band dedicated to PRACH transmission or a slot dedicated to PRACH transmission. This allows the base station device to receive the PRACH corresponding to each synchronization signal using a band or slot dedicated to the PRACH corresponding to the transmitted synchronization signal, thereby allowing the calculation of the propagation delay to be performed more accurately. As a result, the communication device can further improve the quality between wireless links.

[0219] Moreover, the transmitting unit transmits the PRACH to the base station device a predetermined time after the receiving unit receives the synchronization signal. In this way, the communication device can cause the base station device to receive the transmitted PRACH at the original PRACH reception timing by shortening the predetermined time as much as possible.

[0220] In addition, the receiving unit receives time information indicating the predetermined time from the base station device. This allows the communication device to make the base station device receive the PRACH to be transmitted at the PRACH reception timing assumed by the base station device.

[0221] In addition, in the communication method, the communication device receives a synchronization signal transmitted from the base station device, and transmits the PRACH to the base station device using a band dedicated to PRACH transmission or a slot dedicated to PRACH transmission. In this way, the base station device receives the PRACH corresponding to each synchronization signal using a band or slot dedicated to PRACH corresponding to the transmitted synchronization signal, and can more accurately calculate the propagation delay. As a result, the communication device can further improve the quality between the wireless links.

[0222] <<3. Modifications>> The above-described embodiments are merely examples, and various modifications and applications are possible.

[0223] <3-1. Modifications regarding system configuration> In this embodiment, the non-terrestrial station 20, the terrestrial station 30, and the relay station 40 support cellular communication methods such as W-CDMA, cdma2000, LTE, and NR. However, the cellular communication methods supported by the non-terrestrial station 20, the terrestrial station 30, and the relay station 40 are not limited to the above-mentioned cellular communication methods, and may support other cellular communication methods such as UMB (Ultra-Mobile Broadband). Furthermore, these devices may support other wireless communication methods such as a short-distance wireless communication method, a close-proximity wireless communication method, or a wireless LAN (Local Area Network) method in addition to the cellular communication method.

[0224] In the above embodiment, a low-earth orbit satellite constellation is formed by a plurality of non-ground stations 20, but the satellite constellation formed by a plurality of non-ground stations 20 is not limited to a low-earth orbit satellite constellation. The satellite constellation formed by a plurality of non-ground stations 20 may be a medium-earth orbit satellite constellation, a geostationary satellite constellation, or other satellite constellation.

[0225] In addition, in the above-described embodiment, for example, a single base station forms a single cell, but a single cell may be formed by a plurality of base stations in cooperation with each other, and this can be modified as appropriate.

[0226] <3-2. Other modifications> The control device that controls the management device 10, the non-terrestrial station 20, the terrestrial station 30, the relay station 40, or the communication device 50 of this embodiment may be realized by a dedicated computer system or a general-purpose computer system.

[0227] For example, a communication program for executing the above-mentioned operations (e.g., communication processes by the first to third communication methods, etc.) is stored in a computer-readable recording medium such as an optical disk, a semiconductor memory, a magnetic tape, or a flexible disk and distributed. Then, for example, the program is installed in a computer and the above-mentioned processes are executed to configure a control device. In this case, the control device may be a device (e.g., a personal computer) external to the management device 10, the non-terrestrial station 20, the terrestrial station 30, the relay station 40, or the communication device 50. The control device may also be a device (e.g., the control unit 13, the control unit 23, the control unit 34, the control unit 44, or the control unit 55) internal to the non-terrestrial station 20, the terrestrial station 30, the relay station 40, or the communication device 50.

[0228] The communication program may be stored in a disk device provided in a server device on a network such as the Internet, and may be downloaded to a computer. The above-mentioned functions may be realized by cooperation between an OS (Operating System) and application software. In this case, the parts other than the OS may be stored on a medium and distributed, or the parts other than the OS may be stored in a server device and may be downloaded to a computer.

[0229] Furthermore, among the processes described in the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically by a known method. In addition, the information including the processing procedures, specific names, various data and parameters shown in the above documents and drawings can be changed arbitrarily unless otherwise specified. For example, the various information shown in each drawing is not limited to the illustrated information.

[0230] In addition, each component of each device shown in the figure is a functional concept, and does not necessarily have to be physically configured as shown in the figure. In other words, the specific form of distribution and integration of each device is not limited to that shown in the figure, and all or part of them can be functionally or physically distributed and integrated in any unit according to various loads, usage conditions, etc.

[0231] In addition, the above-described embodiments can be combined as appropriate in the areas where the processing contents are not contradictory. In addition, the order of the steps shown in the flowcharts or sequence diagrams of the above-described embodiments can be changed as appropriate.

[0232] <<4. Conclusion>> As described above, according to one embodiment of the present disclosure, the communication device 50 receives a synchronization signal and a PRACH resource transmitted from a base station device. Then, the communication device 50 transmits a PRACH having a feature capable of uniquely identifying the received synchronization signal and / or PRACH resource to the base station device. This allows the base station device to correctly determine the correspondence relationship between the transmitted synchronization signal and PRACH resource and the received PRACH. As a result, the communication device 50 can further improve the quality between the wireless links.

[0233] Although the embodiments of the present disclosure have been described above, the technical scope of the present disclosure is not limited to the above-described embodiments as they are, and various modifications are possible without departing from the gist of the present disclosure. In addition, components of different embodiments and modifications may be appropriately combined.

[0234] Furthermore, the effects of each embodiment described in this specification are merely examples and are not limiting, and other effects may also be provided.

[0235] The present technology can also be configured as follows. (1) A receiving unit that receives a synchronization signal transmitted from a base station device; a transmitter that transmits, to the base station device, a PRACH including a feature that can uniquely identify the synchronization signal and / or a PRACH resource received by the receiver; A communication device having the above configuration. (2) A generator for generating a PRACH including said features The communication device according to (1) above, (3) The above features include: At least one of different resources, sequences, beams, and reference signal ports for each synchronization signal is included. The communication device according to (1) or (2). (4) The above features include: At least one of a preamble sequence, a demodulation reference signal sequence, a scrambling sequence, an interleaving sequence, and a message that is different for each PRACH is included. The communication device according to any one of (1) to (3). (5) The receiving unit is Receive characteristic information indicating the characteristic from the base station device The communication device according to any one of (1) to (4). (6) A calculation unit for deriving the features having The receiving unit is A formula for deriving the characteristic is received from the base station device. The communication device according to any one of (1) to (5). (7) A communication device receiving a synchronization signal transmitted from a base station device; Transmitting a PRACH including a feature capable of uniquely identifying the received synchronization signal and / or the PRACH resource to the base station device. Communication methods. (8) A receiving unit that receives a synchronization signal transmitted from a base station device; a transmitter that transmits the PRACH to the base station device at a timing prior to a transmission timing of the PRACH defined by a PRACH resource; A communication device having the above configuration. (9) A calculation unit for calculating the previous timing The communication device according to (8) above, (10) The calculation unit is The previous timing is calculated based on at least one of location information, movement trajectory information, movement speed information, and altitude information of the base station device and / or the communication device. The communication device according to (9). (11) The calculation unit is Calculating the previous timing based on transmission time information and reception time information of the synchronization signal. The communication device according to (9) or (10). (12) The receiving unit is Receive a formula from the base station device that can derive the previous timing. The communication device according to any one of (9) to (11). (13) The receiving unit is receiving timing information indicating the previous timing from the base station device; The communication device according to (8). (14) A communication device receiving a synchronization signal transmitted from a base station device; Transmitting the PRACH to the base station device at a timing prior to a transmission timing of the PRACH defined by the PRACH resource. Communication methods. (15) A receiving unit that receives a synchronization signal transmitted from a base station device; a transmitter that transmits the PRACH to the base station device using a band dedicated to the PRACH transmission or a slot dedicated to the PRACH transmission; A communication device having the above configuration. (16) The transmission unit is a predetermined time after the synchronization signal is received by the receiving unit, the PRACH is transmitted to the base station device; The communication device according to (15) above. (17) The receiving unit is receiving time information indicating the predetermined time from the base station device; The communication device according to (16). (18) A communication device receiving a synchronization signal transmitted from a base station device; The PRACH is transmitted to the base station device using a band dedicated to the PRACH transmission or a slot dedicated to the PRACH transmission. Communication methods. (19) A computer included in the communication device, A receiving unit that receives a synchronization signal transmitted from a base station device; a transmitter that transmits to the base station device a PRACH including a feature that can uniquely identify the synchronization signal and / or the PRACH resource received by the receiver; A communications program to function as a (20) A computer included in the communication device, A receiving unit that receives a synchronization signal transmitted from a base station device; a transmitter that transmits the PRACH to the base station device at a timing prior to a transmission timing of the PRACH defined by a PRACH resource; A communications program to function as a (twenty one) A computer included in the communication device, A receiving unit that receives a synchronization signal transmitted from a base station device; a transmitter that transmits the PRACH to the base station device using a band dedicated to the PRACH transmission or a slot dedicated to the PRACH transmission; A communications program to function as a (twenty two) A transmitter for transmitting a synchronization signal; A receiving unit that receives the PRACH transmitted from the communication device that received the synchronization signal beyond an expected receiving resource. A base station device having the above configuration. (twenty three) The receiving unit is receiving the PRACH from the communication device, the PRACH including a feature that can uniquely identify the synchronization signal and / or a PRACH resource; The base station device according to (22). (twenty four) A calculation unit that calculates a propagation delay time of the synchronization signal and the PRACH based on a reception timing of the PRACH by the receiving unit. The base station device according to (22) or (23), comprising: (twenty five) A base station device Sends a synchronization signal, The PRACH transmitted from the communication device that received the synchronization signal is received beyond the expected reception resources. Communication methods. (26) A computer included in the base station device, A transmitter for transmitting a synchronization signal; A receiving unit that receives the PRACH transmitted from the communication device that received the synchronization signal beyond the expected receiving resources. A communications program to function as a (27) A transmitter for transmitting a synchronization signal; A receiving unit that receives a PRACH transmitted by the communication device at a timing prior to a transmission timing of the PRACH defined by a PRACH resource; a calculation unit that calculates a propagation delay time of the synchronization signal and the PRACH by adding a time offset of the previous timing to a reception timing of the PRACH by the receiving unit; A base station device having the above configuration. (28) The calculation unit is Calculate the time offset The base station device according to (27). (29) a notification unit that notifies the communication device of the time offset; The base station device according to (27) or (28), comprising: (30) A base station device Sends a synchronization signal, receiving a PRACH transmitted by the communication device at a timing prior to a PRACH transmission timing defined by a PRACH resource; A time offset for the previous timing is added to the reception timing of the PRACH to calculate a propagation delay time of the synchronization signal and the PRACH. Communication methods. (31) A computer included in the base station device, A transmitter for transmitting a synchronization signal; A receiving unit that receives a PRACH transmitted by the communication device at a timing prior to a transmission timing of the PRACH defined by a PRACH resource; a calculation unit that calculates a propagation delay time of the synchronization signal and the PRACH by adding a time offset of the previous timing to a reception timing of the PRACH by the receiving unit; A communications program to function as a (32) A transmitter for transmitting a synchronization signal; a receiving unit that receives the PRACH from the communication device using a band or a slot dedicated to receiving the PRACH; A base station device having the above configuration. (33) A base station device Sends a synchronization signal, Receive the PRACH from the communication device using a band or slot dedicated to receiving the PRACH. Communication methods. (34) A computer included in the base station device, A transmitter for transmitting a synchronization signal; A receiving unit that receives the PRACH from the communication device using a band or a slot dedicated to receiving the PRACH. A communications program to function as a [Explanation of symbols]

[0236] 20 Non-Ground Stations 30 Ground Station 50 Communication equipment 55 Control section

Claims

1. A non-terrestrial station device that wirelessly communicates with a communication device, A transmitter for transmitting orbit information of the non-ground station device; a receiving unit that receives a predetermined signal transmitted at a timing adjusted by the communication device, the adjusted timing is calculated by the communication device based on orbital information of the non-ground device and position information of the communication device; Non-ground station equipment.

2. The transmission unit is Transmitting orbital information of the non-ground station device to the communication device The non-terrestrial station device of claim 1.

3. The receiving unit is receiving a predetermined signal from the communication device, the predetermined signal being transmitted at a timing adjusted by the communication device; 3. A non-terrestrial station device according to claim 1 or 2.

4. The receiving unit is Receive a PRACH (Physical Random Access Channel) preamble transmitted at a timing adjusted by the communication device. A non-terrestrial station device according to any one of claims 1 to 3.

5. The transmitter transmits location information of the non-terrestrial station device to the communication device; the adjusted timing is calculated by the communication device based on location information of the non-terrestrial device and location information of the communication device. The non-terrestrial station device of claim 1.

6. The transmission unit transmits moving speed information of the non-terrestrial station device; the adjusted timing is calculated by the communication device based on location information and movement speed information of the non-terrestrial device and location information of the communication device; The non-terrestrial station device of claim 5.

7. A communication method in which a non-terrestrial station device wirelessly communicates with a communication device, comprising: Transmitting orbital information of the non-ground station device; receiving a predetermined signal transmitted at a timing adjusted by the communication device; the adjusted timing is calculated by the communication device based on orbital information of the non-ground device and position information of the communication device; Communication methods.

8. The predetermined signal is PRACH preamble The communication method according to claim 7.

9. Transmitting location information of the non-terrestrial device; the adjusted timing is calculated by the communication device based on location information of the non-terrestrial device and location information of the communication device. The communication method according to claim 7.

10. Transmitting the moving speed information of the non-ground station device; the adjusted timing is calculated by the communication device based on location information and movement speed information of the non-terrestrial device and location information of the communication device; The communication method according to claim 9.

11. A communication device that performs wireless communication with a non-terrestrial station device, A receiving unit for receiving orbit information of the non-ground station device; A calculation unit that calculates a timing for transmitting a predetermined signal; a transmitter that transmits a predetermined signal at the adjusted timing, The timing of transmission is calculated by the calculation unit based on orbit information of the non-ground station device and position information of the communication device. Communications equipment.

12. The receiving unit is Receive orbit information of the non-ground station device from the non-ground station device. The communication device according to claim 11.

13. The transmission unit is Transmitting a predetermined signal to the non-terrestrial station device at the adjusted timing. A communication device according to claim 11 or 12.

14. The transmission unit is Transmit the PRACH preamble at the adjusted timing A communication device according to any one of claims 11 to 13.

15. The receiving unit receives position information of the non-terrestrial station device, The timing of transmission is calculated by the calculation unit based on the position information of the non-terrestrial station device and the position information of the communication device. The communication device according to claim 11.

16. The receiving unit receives moving speed information of the non-terrestrial station device, The timing of transmission is calculated by the calculation unit based on the position information and moving speed information of the non-terrestrial station device and the position information of the communication device.

16. The communication device of claim 15.

17. A communication method in which a communication device wirelessly communicates with a non-terrestrial station device, comprising: receiving orbital information of the non-ground station device; Calculating a timing for transmitting a predetermined signal based on orbit information of the non-ground station device and position information of the communication device; Transmitting a predetermined signal at the adjusted timing. Communication methods.

18. The predetermined signal is PRACH preamble 20. The communication method according to claim 17.

19. receiving location information of the non-terrestrial device; Calculating a timing for transmitting a predetermined signal based on location information of the non-terrestrial station device and location information of the communication device; 20. The communication method according to claim 17.

20. receiving information on the moving speed of the non-ground station device; Calculating a timing for transmitting a predetermined signal based on the location information and moving speed information of the non-terrestrial station device and the location information of the communication device; 20. The communication method of claim 19.

Images