Base station, terminal, and communication method

Abstract

This base station receives a first measurement report including a first cell identifier from a terminal, recognizes that a cell corresponding to the first cell identifier cannot be determined to belong to a satellite group to which the local device belongs, transmits, to the terminal, a request message related to a report on a neighboring cell belonging to the satellite group to which the local device belongs, receives, from the terminal, a message including a frequency channel number used by the neighboring cell belonging to the satellite group to which the local device belongs, transmits, to the terminal, a message requesting a measurement report including a cell identifier related to the frequency channel number, receives a second measurement report including a second cell identifier from the terminal, determines that a cell corresponding to the second cell identifier belongs to the satellite group to which the local device belongs, selects the cell corresponding to the second cell identifier as a handover destination on the basis of the second measurement report, and transmits a handover request to another base station that accommodates the cell corresponding to the second cell identifier.

Description

Base station, terminal, and communication method

[0001] The present invention relates to a base station, a terminal, and a communication method in a communication system.

[0002] 3GPP (registered trademark) (3rd Generation Partnership Project) is currently studying a wireless communication system called 5G or NR (New Radio) (hereinafter, the wireless communication system will be referred to as "5G" or "NR") in order to achieve a larger system capacity, a higher data transmission speed, and a lower latency in wireless sections. Various wireless technologies are being studied for 5G to meet the requirements of achieving a throughput of 10 Gbps or more while keeping latency in wireless sections to 1 ms or less.

[0003] In NR, a network architecture including 5GC (5G Core Network) corresponding to EPC (Evolved Packet Core), which is the core network in the network architecture of LTE (Long Term Evolution), and NG-RAN (Next Generation - Radio Access Network) corresponding to E-UTRAN (Evolved Universal Terrestrial Radio Access Network), which is the RAN (Radio Access Network) in the network architecture of LTE, is being considered (for example, Non-Patent Document 1).

[0004] Furthermore, as an IMS (IP Multimedia Subsystem) architecture that supports the data channel capabilities of terminals, specifications for an IMS data channel network are being studied (see, for example, Non-Patent Document 2). In the IMS data channel network, a Data Channel Signalling Function (DCSF) having a signaling function, a Media Function (MF) having a media-related function, and a Data Channel Application Server (DCAS) that is an application server are arranged on both the calling and called sides.

[0005] Furthermore, in 3GPP Rel-19, in order to realize IMS voice terminal-satellite-terminal communication (UE-satellite-UE communication), reducing the impact on existing specifications when deploying 5GC network functions and IMS components on satellites is an issue (see, for example, Non-Patent Document 3). Here, terminal-satellite-terminal communication refers to terminal-to-terminal communication under routing that keeps user plane traffic within the satellite. The types of satellites handled include geostationary satellites (GEO), low Earth orbit satellites (LEO), and medium Earth orbit satellites (MEO). Furthermore, for low Earth orbit satellites and medium Earth orbit satellites, satellite constellations can be formed without using inter-satellite links (ISLs) or using inter-satellite links.

[0006] 3GPP TS 23.501 V18.5.0 (2024-06) 3GPP TS 23.228 V18.6.0 (2024-06) 3GPP TR23.700-29 V19.0.0 (2024-06) 3GPP TS 38.331 V18.1.0 (2024-03)

[0007] In satellite constellation communications, when a handover occurs while voice media is being routed over the satellite constellation, ground fallback, which falls back to the terrestrial network, may be performed for the voice media routing. In this case, handover should be performed without ground fallback whenever possible, but this procedure has not been studied.

[0008] The present invention has been made in view of the above points, and has as its object to perform handover in a wireless communication system using a satellite without ground fallback as much as possible.

[0009] According to the disclosed technology, a mobile station includes a receiving unit that receives from a terminal a first message related to a first signal strength measurement report including a first physical cell identifier, a control unit that recognizes that it cannot be determined that a cell corresponding to the first physical cell identifier belongs to a satellite constellation to which the mobile station belongs, and a transmitting unit that transmits to the terminal a second message requesting a report of nearby cells that belong to the satellite constellation to which the mobile station belongs, wherein the receiving unit receives from the terminal a third message including a radio frequency channel number used by a nearby cell that belongs to the satellite constellation to which the mobile station belongs, and the transmitting unit transmits to the terminal a second message requesting a report of nearby cells that belong to the satellite constellation to which the mobile station belongs. the receiving unit receives from the terminal a fifth message relating to a second signal strength measurement report including a second physical cell identifier; the control unit determines that a cell corresponding to the second physical cell identifier belongs to a satellite constellation to which the terminal belongs; the control unit selects, based on the second signal strength measurement report, the cell corresponding to the second physical cell identifier as a destination for handover; and the transmitting unit transmits a sixth message requesting handover to another base station that accommodates the cell corresponding to the second physical cell identifier.

[0010] According to the disclosed technology, handover can be performed in a wireless communication system using a satellite without ground fallback as much as possible.

[0011] FIG. 1 is a diagram for explaining an example of a communication system. FIG. 2 is a diagram for explaining an example of a communication system in a roaming environment. FIG. 3 is a diagram for explaining an example of an IMS data channel network. FIG. 4 is a diagram showing an example of a sequence diagram in an embodiment of the present invention. FIG. 5 is a diagram showing an example of the functional configuration of a base station 10 and a network node 30 in an embodiment of the present invention. FIG. 6 is a diagram showing an example of the functional configuration of a terminal 20 in an embodiment of the present invention. FIG. 7 is a diagram showing an example of the hardware configuration of a base station 10, a terminal 20, and a network node 30 in an embodiment of the present invention. FIG. 8 is a diagram showing an example of the configuration of a vehicle 2001 in an embodiment of the present invention.

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below is an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

[0013] In the operation of the wireless communication system according to the embodiment of the present invention, existing technology is used as appropriate. However, the existing technology is, for example, the existing LTE, but is not limited to the existing LTE. Furthermore, the term "LTE" used in this specification has a broad meaning including LTE-Advanced, and systems subsequent to LTE-Advanced (e.g., NR), or wireless LAN (Local Area Network), unless otherwise specified.

[0014] Furthermore, in the embodiments of the present invention, "configuring" radio parameters and the like may mean that predetermined values ​​are pre-configured, or that radio parameters notified from the network node 30 or the terminal 20 are set.

[0015] Fig. 1 is a diagram illustrating an example of a communication system. As shown in Fig. 1, the communication system is composed of a UE, which is a terminal 20, and multiple network nodes 30. Hereinafter, it is assumed that one network node 30 corresponds to each function, but multiple functions may be realized by one network node 30, or multiple network nodes 30 may realize one function. Furthermore, the "connection" described below may be a logical connection or a physical connection.

[0016] The RAN (Radio Access Network) is a network node 30 having a radio access function, which may include a base station 10, and is connected to a UE, an AMF (Access and Mobility Management Function), and a UPF (User Plane Function). The AMF is a network node 30 having functions such as terminating the RAN interface, terminating the NAS (Non-Access Stratum), registering management, connecting management, reachability management, and terminal mobility management. The UPF is a network node 30 having functions related to processing user plane data, such as a PDU (Protocol Data Unit) session point to the outside that interconnects with the DN (Data Network), packet routing and forwarding, and user plane Quality of Service (QoS) handling. The UPF and the DN constitute a network slice. In the wireless communication network according to the embodiment of the present invention, multiple network slices are constructed.

[0017] The AMF is connected to the UE, RAN, SMF (Session Management function), NSSF (Network Slice Selection Function), NEF (Network Exposure Function), NRF (Network Repository Function), UDM (Unified Data Management), AUSF (Authentication Server Function), PCF (Policy Control Function), and AF (Application Function). The AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are mutually connected via interfaces based on their respective services, Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

[0018] The SMF is a network node 30 having functions such as session management, UE IP (Internet Protocol) address allocation and management, DHCP (Dynamic Host Configuration Protocol) function, ARP (Address Resolution Protocol) proxy, and roaming function. The NEF is a network node 30 having a function of notifying other NFs (Network Functions) of capabilities and events. The NSSF is a network node 30 having functions such as selecting a network slice to which a UE connects, determining an allowed NSSAI (Network Slice Selection Assistance Information), determining an NSSAI to be set, and determining an AMF set to which a UE connects. The PCF is a network node 30 having a function of controlling network policies. The AF is a network node 30 having a function of controlling application servers. The NRF is a network node 30 having a function of discovering NF instances that provide services. The UDM is a network node 30 that manages subscriber data and authentication data. The UDM is connected to a UDR (User Data Repository) that stores the data.

[0019] Fig. 2 is a diagram illustrating an example of a communication system in a roaming environment. As shown in Fig. 2, the network is composed of a UE, which is a terminal 20, and multiple network nodes 30. Hereinafter, it is assumed that one network node 30 corresponds to each function, but multiple functions may be realized by one network node 30, or multiple network nodes 30 may realize one function. Furthermore, the "connection" described below may be a logical connection or a physical connection.

[0020] The RAN is a network node 30 having a radio access function, and is connected to the UE, the AMF, and the UPF. The AMF is a network node 30 having functions such as RAN interface termination, NAS termination, registration management, connection management, reachability management, and mobility management. The UPF is a network node 30 having functions such as a PDU session point to the outside that interconnects with the DN, packet routing and forwarding, and user plane QoS handling. The UPF and the DN constitute a network slice. In the wireless communication network according to the embodiment of the present invention, multiple network slices are constructed.

[0021] The AMF is connected to the UE, RAN, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, AF, and SEPP (Security Edge Protection Proxy). The AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are interconnected via respective service-based interfaces, Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

[0022] The SMF is a network node 30 having functions such as session management, UE IP address allocation and management, DHCP function, ARP proxy, and roaming function. The NEF is a network node 30 having a function of notifying other NFs of capabilities and events. The NSSF is a network node 30 having functions such as selecting a network slice to which a UE connects, determining an allowed NSSAI, determining a configured NSSAI, and determining an AMF set to which a UE connects. The PCF is a network node 30 having a function of controlling network policies. The AF is a network node 30 having a function of controlling application servers. The NRF is a network node 30 having a function of discovering NF instances that provide services. The SEPP is a non-transparent proxy that filters control plane messages between PLMNs (Public Land Mobile Networks). The vSEPP shown in FIG. 2 is a SEPP in the visited network, and the hSEPP is a SEPP in the home network.

[0023] As shown in Figure 2, a UE is in a roaming environment connected to a RAN and an AMF in a Visited PLMN (VPLMN). The VPLMN and a Home PLMN (HPLMN) are connected via a vSEPP and an hSEPP. The UE can communicate with a UDM in the HPLMN via the AMF in the VPLMN, for example.

[0024] Fig. 3 is a diagram illustrating an example of an IMS data channel network. As shown in Fig. 3, the IMS data channel network is configured with a terminal 20 (UE) and multiple network nodes 30 in each of an originating network and a terminating network. Hereinafter, it is assumed that one network node 30 corresponds to each function, but multiple functions may be realized by one network node 30, or multiple network nodes 30 may realize one function. Furthermore, the "connection" described below may be a logical connection or a physical connection. The network node 30 has, for example, the following functions described in Non-Patent Document 2:

[0025] The IMS-AGW (Access Gateway) is a network node 30 having a gateway function between the UE and the IMS network, a function related to access processing for voice communication, and the like.

[0026] A P-CSCF (Proxy-Call Session Control Function) is a network node 30 that has a proxy function between the UE and the IMS network, an access control function for voice communication, and the like.

[0027] The S-CSCF (Serving-Call Session Control Function) is a network node 30 having functions related to session control for the UE.

[0028] The I-CSCF (Interrogate-Call Session Control Function) is a connection point on the destination network side between networks (e.g., between the source network side and the destination network side) in the IMS network, and is a network node 30 that has, for example, the function of forwarding a received SIP request to the S-CSCF of its own network.

[0029] An IMS AS (IP Multimedia Subsystem Application Server) is a network node 30 in an IMS network that has functions such as communicating with a DCSF for event notification and receiving data channel control instructions from the DCSF to communicate with an MF. The IMS AS also receives a communication termination point registration request from a DCSF (Data Channel Signalling Function), converts the received registration request into a SIP Register, and sends it to a Serving-Call Session Control Function (S-CSCF). The IMS AS also converts a data channel establishment request received from the DCSF into a SIP INVITE and sends it to the S-CSCF.

[0030] The DCSF (Data Channel Signaling Function) is a network node 30 that has functions such as receiving an event report from the IMS-AS and determining whether to allow the provision of a data channel service, managing the bootstrap data channel, and performing HTTP web server functions.

[0031] An MF (Media Function) is a network node 30 in an IMS network that has functions such as media resource management and forwarding of data channel media traffic. The MF processes media between a DCAS (Data Channel Application Server), which is a communication termination point, and a destination termination point based on configuration information received from a DCSF. The MF may also be called a DCMF (Data Channel Media Function). The MF may also be called an MRF (Multimedia Resource Function).

[0032] A DCAS (Data Channel Application Server) is a network node 30 having functions such as a communication termination point for media and signaling in the IMS network.

[0033] (Example) In satellite constellation communications, when a handover occurs while voice media is being routed over the satellite constellation, ground fallback, which falls back to a terrestrial network, may be performed for the routing of the voice media. In this case, handover should be performed without ground fallback whenever possible. In this example, a procedure for performing handover in a wireless communication system using satellites without ground fallback whenever possible will be described.

[0034] In this embodiment, it is assumed that the base station 10 is unable to determine that the destination candidate cell belongs to the same satellite constellation based on the value of the physical cell ID (PCI) in the measurement report. Here, the measurement report may be referred to as a signal strength measurement report because it includes a report on the signal strength received from the base station 10. The base station 10 also causes the terminal 20 to report nearby cells belonging to the satellite constellation to which the base station 10 belongs and the signal strength of the nearby cells. Furthermore, if a nearby cell belonging to the satellite constellation to which the base station 10 belongs has sufficient signal strength, the base station 10 preferentially selects the nearby cell as the handover destination. Note that each base station 10 transmits broadcast information (System Information Block, SIB) including the satellite constellation identifier to the terminal 20 via a broadcast channel (BCCH).

[0035] The details of the processing in this embodiment will be described below using a sequence diagram. Requests, responses, notifications, etc. transmitted and received in the procedures described below may be referred to as messages (e.g., request messages). FIG. 4 shows an example of a sequence diagram in an embodiment of the present invention. For details of existing specifications regarding messages transmitted and received in this sequence, refer to Non-Patent Document 4, etc. In this sequence, the terminal 20 performs a handover from the base station 10A (source base station) to the base station 10C (destination base station) that belongs to the same satellite constellation as the base station 10A, rather than to the base station 10B that belongs to a different satellite constellation from the base station 10A. The processing of each step will be described below.

[0036] S101: The base station 10B transmits a synchronization signal block (SSB) to the terminal 20. The synchronization signal block includes a physical cell identifier (PCI). The PCI value is denoted as b, and is expressed as PCI=b.

[0037] S102: The terminal 20 transmits a measurement report of the signal strength to the base station 10 A. The measurement report includes the PCI value (PCI=b) received in S101.

[0038] S103: The base station 10A recognizes, based on the PCI value (PCI=b) included in the measurement report received in S102, that it cannot determine that the cell corresponding to the PCI value belongs to the satellite constellation to which the base station 10A belongs. For example, the base station 10A may derive a satellite constellation identifier based on the PCI value, and recognize that the derived satellite constellation identifier is different from the satellite constellation identifier to which the base station 10A belongs.

[0039] S104: The base station 10A decides to instruct the terminal 20 to report nearby cells that belong to the satellite constellation to which the terminal belongs.

[0040] S105: The base station 10A transmits a message (RRCReconfiguration) related to RRC configuration, including an instruction to report nearby cells belonging to the satellite constellation to which the base station 10A belongs, to the terminal 20. For example, the message is expressed as RRCReconfiguration (Report Satellite-proximity Config).

[0041] S106: The terminal 20 transmits to the base station 10A a message (RRCReconfigurationComplete) indicating completion of the RRC configuration as a response to the message received in S105.

[0042] S107: The terminal 20 performs a search for nearby cells belonging to the satellite constellation that currently contains the base station 10A. This search can be performed using an autonomous gap (see Non-Patent Document 4, etc.).

[0043] S108: The terminal 20 receives notification information (SIB) transmitted on the broadcast channel from the base station 10C. The notification information includes an identifier of the satellite constellation in which the base station 10C is located.

[0044] S109: The terminal 20 transmits to the base station 10A a message (Satellite-proximity indication) in response to the instruction contained in the message received in S105. The message includes the absolute radio-frequency channel number (ARFCN) used by a nearby cell belonging to the satellite constellation to which the base station 10A belongs. For example, the message is expressed as Satellite-proximity indication (type=entering, carrierFreq(ARFCN-ValueNR)).

[0045] S110: If the frequency reported by the terminal 20 in S109 is not a measurement target, the base station 10A determines to set it to be a measurement target.

[0046] S111: The base station 10A transmits, to the terminal 20, a message (RRCReconfiguration) related to RRC configuration, including a setting for setting the frequency reported by the terminal 20 in S109 as a measurement target. For example, this message is expressed as RRCReconfiguration (Measurement Config).

[0047] S112: The terminal 20 transmits to the base station 10A a message (RRCReconfigurationComplete) indicating completion of the RRC configuration as a response to the message received in S111.

[0048] S113: The base station 10C transmits a synchronization signal block (SSB) to the terminal 20. The synchronization signal block includes a physical cell identifier (PCI). The PCI value is denoted as c, and is expressed as PCI=c.

[0049] S114: The terminal 20 transmits a signal strength measurement report to the base station 10 A. The measurement report includes the PCI value (PCI=c) received in S113.

[0050] S115: Based on the PCI value (PCI=c) included in the measurement report received in S114, the base station 10A determines that the cell corresponding to the PCI value belongs to the satellite constellation to which the base station 10A belongs. For example, the base station 10A may make this determination by deriving the identifier of the satellite constellation corresponding to the PCI value using a mapping table stored in the base station 10A. Alternatively, if the base station 10A cannot use the mapping table, the base station 10A may make this determination by executing the processes from S116 to S119.

[0051] S116: The base station 10A transmits to the terminal 20 a message (RRCReconfiguration) relating to RRC configuration, which includes a request to report broadcast information specifying the PCI value (PCI=c) included in the measurement report received in S114.

[0052] S117: The terminal 20 transmits to the base station 10A a message (RRCReconfigurationComplete) indicating completion of the RRC configuration as a response to the message received in S111.

[0053] S118: The terminal 20 receives notification information transmitted on the broadcast channel from the base station 10C. The notification information includes an identifier of the satellite constellation in which the base station 10C is located.

[0054] S119: The terminal 20 transmits a measurement report to the base station 10A in response to the request received in S116. The measurement report includes the identifier of the satellite constellation containing the base station 10C received in S118.

[0055] S120: The base station 10A determines that the cell corresponding to the PCI value (PCI=c) acquired in S116 to S119 belongs to the satellite constellation to which the base station 10A belongs. The base station 10A also stores the PCI value (PCI=c) and the satellite constellation identifier in association with each other for future use.

[0056] S121: The base station 10A selects a nearby cell (base station 10C) belonging to the satellite constellation to which the base station 10A belongs as the destination for handover, with priority given to that cell, based on the fact that the signal transmitted from that cell has sufficient signal strength (for example, strength equal to or greater than a predetermined threshold).

[0057] S122: The base station 10A sends a handover request to the base station 10C. Here, the base station 10C, which is the destination base station, is accommodated by the same satellite constellation as the base station 10A, so ground fallback is not performed during handover. On the other hand, if the destination base station is the base station 10B, which is accommodated by a different satellite constellation than the base station 10A, ground fallback may be performed during handover.

[0058] According to the above-described embodiment, handover can be performed without ground fallback as much as possible in a wireless communication system using a satellite.

[0059] (Device Configuration) Next, a description will be given of an example of the functional configuration of the base station 10, network node 30, and terminal 20 that perform the processes and operations described above. The base station 10, network node 30, and terminal 20 include functions for performing the above-described embodiments. However, the base station 10, network node 30, and terminal 20 may each include only a part of the functions of the embodiments.

[0060] <Base Station 10 and Network Node 30> Fig. 5 is a diagram showing an example of the functional configuration of the base station 10 and the network node 30. As shown in Fig. 5, the base station 10 has a transmitting unit 110, a receiving unit 120, a setting unit 130, and a control unit 140. The functional configuration shown in Fig. 5 is merely an example. As long as the operations according to the embodiment of the present invention can be performed, the names of the functional divisions and functional units may be any. Note that the network node 30 may have the same functional configuration as the base station 10. Furthermore, a network node 30 having multiple different functions in the system architecture may be composed of multiple network nodes 30 separated by function.

[0061] The transmitter 110 includes a function of generating a signal to be transmitted to the terminal 20 or another network node 30 and transmitting the signal by wire or wirelessly. The receiver 120 includes a function of receiving various signals transmitted from the terminal 20 or another network node 30 and acquiring, for example, information of a higher layer from the received signal. A communication unit including the transmitter 110 and the receiver 120 may be configured.

[0062] The setting unit 130 stores preset setting information and various setting information to be transmitted to the terminal 20 in a storage device, and reads out the information from the storage device as needed.

[0063] The control unit 140 performs the processes described in the embodiments, etc. The control unit 140 also performs processes related to communication with the terminal 20. The function unit related to signal transmission in the control unit 140 may be included in the transmitting unit 110, and the function unit related to signal reception in the control unit 140 may be included in the receiving unit 120.

[0064] <Terminal 20> Fig. 6 is a diagram showing an example of the functional configuration of the terminal 20. As shown in Fig. 6, the terminal 20 has a transmitting unit 210, a receiving unit 220, a setting unit 230, and a control unit 240. The functional configuration shown in Fig. 6 is merely an example. As long as the operations related to the embodiment of the present invention can be performed, the names of the functional divisions and functional units may be any. In addition, a communication device that becomes a resource holder 20 may have the same functional configuration as the terminal 20.

[0065] The transmitter 210 creates a transmission signal from transmission data and transmits the transmission signal wirelessly. The receiver 220 receives various signals wirelessly and acquires higher layer signals from the received physical layer signals. The receiver 220 also has a function of receiving control signals, reference signals, etc. transmitted from the network node 30. A communication unit including the transmitter 210 and the receiver 220 may be configured.

[0066] The setting unit 230 stores various setting information received from the network node 30 by the receiving unit 220 in a storage device, and reads it out from the storage device as needed. The setting unit 230 also stores setting information that is set in advance.

[0067] The control unit 240 performs the processes described in the embodiments. The function unit related to signal transmission in the control unit 240 may be included in the transmitting unit 210, and the function unit related to signal reception in the control unit 240 may be included in the receiving unit 220.

[0068] (Hardware Configuration) The block diagrams (FIGS. 5 and 6) used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wires, wirelessly, etc.) and these multiple devices. The functional block may be realized by combining software with the single device or the multiple devices.

[0069] Functions include, but are not limited to, judgment, determination, assessment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, consideration, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assignment. For example, a functional block (component) that performs transmission is called a transmitting unit or transmitter. As mentioned above, there are no particular limitations on how these functions are implemented.

[0070] For example, the base station 10, the network node 30, the terminal 20, etc. according to an embodiment of the present disclosure may function as a computer that performs processing of the wireless communication method of the present disclosure. Fig. 7 is a diagram illustrating an example of the hardware configuration of the base station 10 and the terminal 20 according to an embodiment of the present disclosure. The network node 30 may have the same hardware configuration as the base station 10. The above-described base station 10 and the terminal 20 may be physically configured as a computer device including a processor 1001, a storage device 1002, an auxiliary storage device 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0071] In the following description, the term "apparatus" can be interpreted as a circuit, a device, a unit, etc. The hardware configuration of the base station 10 and the terminal 20 may be configured to include one or more of the apparatuses shown in the drawings, or may be configured to exclude some of the apparatuses.

[0072] Each function in the base station 10 and the terminal 20 is realized by loading specified software (programs) onto hardware such as the processor 1001, the memory device 1002, etc., so that the processor 1001 performs calculations, controls communication by the communication device 1004, and controls at least one of reading and writing data in the memory device 1002 and the auxiliary memory device 1003.

[0073] The processor 1001 controls the entire computer by running, for example, an operating system. The processor 1001 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc. For example, the above-mentioned control unit 140, control unit 240, etc. may be realized by the processor 1001.

[0074] Furthermore, the processor 1001 reads programs (program codes), software modules, data, etc. from at least one of the auxiliary storage device 1003 and the communication device 1004 into the storage device 1002 and executes various processes in accordance with the programs. The programs used are those that cause a computer to execute at least some of the operations described in the above-described embodiments. For example, the control unit 140 of the base station 10 shown in FIG. 5 may be implemented by a control program stored in the storage device 1002 and running on the processor 1001. Furthermore, for example, the control unit 240 of the terminal 20 shown in FIG. 6 may be implemented by a control program stored in the storage device 1002 and running on the processor 1001. While the above-described various processes have been described as being executed by one processor 1001, they may also be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may also be transmitted from a network via a telecommunications line.

[0075] The storage device 1002 is a computer-readable recording medium and may be configured, for example, by at least one of a read-only memory (ROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a random access memory (RAM), etc. The storage device 1002 may also be called a register, a cache, a main memory, etc. The storage device 1002 can store executable programs (program codes), software modules, etc. for implementing a communication method according to an embodiment of the present disclosure.

[0076] The secondary storage device 1003 is a computer-readable recording medium, and may be, for example, at least one of an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray (registered trademark) disk), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy (registered trademark) disk, a magnetic strip, etc. The above-mentioned storage medium may be, for example, a database, a server, or other appropriate medium including at least one of the storage device 1002 and the secondary storage device 1003.

[0077] The communication device 1004 is hardware (transmission / reception device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as, for example, a network device, a network controller, a network card, a communication module, etc. The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, a transmission / reception antenna, an amplifier unit, a transmission / reception unit, a transmission path interface, etc. may be realized by the communication device 1004. The transmission / reception unit may be implemented as a transmission unit and a reception unit that are physically or logically separated.

[0078] The input device 1005 is an input device (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that accepts input from the outside. The output device 1006 is an output device (e.g., a display, a speaker, an LED lamp, etc.) that outputs to the outside. Note that the input device 1005 and the output device 1006 may be integrated into one device (e.g., a touch panel).

[0079] Furthermore, each device such as the processor 1001 and the storage device 1002 is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

[0080] Furthermore, the base station 10 and the terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA), and some or all of the functional blocks may be realized by the hardware. For example, the processor 1001 may be implemented using at least one of these pieces of hardware.

[0081] Fig. 8 shows an example configuration of a vehicle 2001. As shown in Fig. 8, the vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, front wheels 2007, rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021 to 2029, an information service unit 2012, and a communication module 2013. Each aspect / embodiment described in the present disclosure may be applied to a communication device mounted on the vehicle 2001, and may be applied to the communication module 2013, for example.

[0082] The drive unit 2002 is configured, for example, by an engine, a motor, or a hybrid of an engine and a motor. The steering unit 2003 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels and the rear wheels based on the operation of the steering wheel operated by the user.

[0083] The electronic control unit 2010 is composed of a microprocessor 2031, a memory (ROM, RAM) 2032, and a communication port (IO port) 2033. Signals are input to the electronic control unit 2010 from various sensors 2021 to 2029 provided in the vehicle 2001. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0084] The signals from the various sensors 2021 to 2029 include a current signal from a current sensor 2021 that senses the current of the motor, a rotation speed signal of the front and rear wheels obtained by a rotation speed sensor 2022, an air pressure signal of the front and rear wheels obtained by an air pressure sensor 2023, a vehicle speed signal obtained by a vehicle speed sensor 2024, an acceleration signal obtained by an acceleration sensor 2025, an accelerator pedal depression amount signal obtained by an accelerator pedal sensor 2029, a brake pedal depression amount signal obtained by a brake pedal sensor 2026, a shift lever operation signal obtained by a shift lever sensor 2027, and a detection signal for detecting obstacles, vehicles, pedestrians, etc. obtained by an object detection sensor 2028.

[0085] The information service unit 2012 is composed of various devices, such as a car navigation system, an audio system, speakers, a television, and a radio, for providing (outputting) various types of information, such as driving information, traffic information, and entertainment information, and one or more ECUs for controlling these devices. The information service unit 2012 uses information acquired from external devices via the communication module 2013 or the like to provide various types of multimedia information and multimedia services to the occupants of the vehicle 2001. The information service unit 2012 may include input devices (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, a touch panel, etc.) that accept input from the outside, and may also include output devices (e.g., a display, a speaker, an LED lamp, a touch panel, etc.) that output information to the outside.

[0086] The driving assistance system unit 2030 is composed of various devices that provide functions for preventing accidents and reducing the driving burden on the driver, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS, etc.), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps, etc.), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System), etc.), AI (Artificial Intelligence) chips, and AI processors, as well as one or more ECUs that control these devices. In addition, the driving assistance system unit 2030 transmits and receives various information via the communication module 2013 to realize the driving assistance function or the autonomous driving function.

[0087] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via the communication port. For example, the communication module 2013 transmits and receives data via the communication port 2033 to and from the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axle 2009, microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021 to 29, which are provided in the vehicle 2001.

[0088] The communication module 2013 is a communication device that can be controlled by the microprocessor 2031 of the electronic control unit 2010 and can communicate with an external device. For example, it transmits and receives various information to and from the external device via wireless communication. The communication module 2013 may be located either inside or outside the electronic control unit 2010. The external device may be, for example, a base station, a mobile station, or the like.

[0089] The communication module 2013 may transmit at least one of signals from the above-mentioned various sensors 2021-2028 input to the electronic control unit 2010, information obtained based on the signals, and information based on input from the outside (user) obtained via the information service unit 2012 to an external device via wireless communication. The electronic control unit 2010, the various sensors 2021-2028, the information service unit 2012, etc. may be referred to as input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include information based on the above-mentioned input.

[0090] The communication module 2013 receives various information (traffic information, traffic signal information, vehicle-to-vehicle information, etc.) transmitted from external devices and displays it on an information service unit 2012 provided in the vehicle 2001. The information service unit 2012 may be called an output unit that outputs information (for example, outputs information to a device such as a display or speaker based on the PDSCH (or data / information decoded from the PDSCH) received by the communication module 2013). The communication module 2013 also stores the various information received from external devices in a memory 2032 that can be used by the microprocessor 2031. Based on the information stored in the memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axles 2009, sensors 2021 to 2029, etc. provided in the vehicle 2001.

[0091] <Supplementary Notes> (Supplementary Note 1) A mobile station includes: a receiver that receives, from a terminal, a first message related to a first signal strength measurement report including a first physical cell identifier; a controller that recognizes that it cannot be determined that a cell corresponding to the first physical cell identifier belongs to a satellite constellation to which the terminal belongs; and a transmitter that transmits, to the terminal, a second message requesting a report of nearby cells belonging to the satellite constellation to which the terminal belongs; wherein the receiver receives from the terminal a third message including a radio frequency channel number used by nearby cells belonging to the satellite constellation to which the terminal belongs; the transmitter transmits to the terminal a fourth message requesting a measurement report including a physical cell identifier related to the radio frequency channel number; the receiver receives from the terminal a fifth message related to a second signal strength measurement report including a second physical cell identifier; the controller determines that the cell corresponding to the second physical cell identifier belongs to the satellite constellation to which the terminal belongs; and the controller selects the cell corresponding to the second physical cell identifier as a handover destination based on the second signal strength measurement report. a base station comprising: a receiving unit configured to receive, from a base station, a first message requesting a report of nearby cells belonging to a currently accommodated satellite constellation; a control unit configured to search for nearby cells belonging to the currently accommodated satellite constellation; and a transmitting unit configured to transmit, to the base station, a second message including a radio frequency channel number used by nearby cells belonging to the currently accommodated satellite constellation.(Supplementary Item 4) A terminal having: a receiving unit that receives, from a first base station, a message requesting a report of broadcast information specifying a physical cell identifier; and a receiving unit that receives, from a second base station, broadcast information including a satellite constellation identifier of a cell corresponding to the physical cell identifier; and a transmitting unit that transmits a report of the broadcast information including the satellite constellation identifier to the first base station. (Supplementary clause 5) Receiving a first message relating to a first signal strength measurement report including a first physical cell identifier from a terminal; recognizing that it cannot be determined that a cell corresponding to the first physical cell identifier belongs to the satellite constellation to which the terminal belongs; transmitting a second message to the terminal requesting a report of nearby cells belonging to the satellite constellation to which the terminal belongs; receiving a third message from the terminal including a radio frequency channel number used by a nearby cell belonging to the satellite constellation to which the terminal belongs; transmitting a fourth message to the terminal requesting a measurement report including a physical cell identifier for the radio frequency channel number; receiving a fifth message from the terminal related to a second signal strength measurement report including a second physical cell identifier; determining that a cell corresponding to the second physical cell identifier belongs to the satellite constellation to which the terminal belongs; selecting the cell corresponding to the second physical cell identifier as a handover destination based on the second signal strength measurement report; sending a sixth message requesting a handover to another base station accommodating a cell corresponding to the second physical cell identifier.

[0092] Any of Supplementary Items 1 to 5 makes it possible to execute handover in a wireless communication system using a satellite without resorting to ground fallback as much as possible.

[0093] (Supplementary Notes on the Embodiments) Although the embodiments of the present invention have been described above, the disclosed invention is not limited to such embodiments, and those skilled in the art will understand various modifications, alterations, alternatives, and substitutions. While specific numerical examples have been used to facilitate understanding of the invention, unless otherwise specified, these numerical values ​​are merely examples, and any appropriate values ​​may be used. The division of items in the above description is not essential to the present invention; matters described in two or more items may be used in combination as needed, and matters described in one item may apply to matters described in another item (as long as there is no contradiction). Boundaries between functional units or processing units in functional block diagrams do not necessarily correspond to boundaries between physical components. The operations of multiple functional units may be performed by a single physical component, or the operations of a single functional unit may be performed by multiple physical components. The order of processing steps described in the embodiments may be reversed as long as there is no contradiction. For convenience of processing description, the base station 10 and terminal 20 have been described using functional block diagrams, but such devices may be realized by hardware, software, or a combination thereof. The software operated by the processor of the base station 10 in accordance with an embodiment of the present invention and the software operated by the processor of the terminal 20 in accordance with an embodiment of the present invention may each be stored in random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, register, hard disk (HDD), removable disk, CD-ROM, database, server, or any other suitable storage medium.

[0094] Furthermore, the notification of information is not limited to the aspects / embodiments described in the present disclosure, and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, Medium Access Control (MAC) signaling), broadcast information (Master Information Block (MIB), System Information Block (SIB)), other signals, or a combination thereof. Furthermore, the RRC signaling may be referred to as an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, or the like.

[0095] Each aspect / embodiment described in the present disclosure may be implemented using any of the following standards: LTE (Long Term Evolution), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (xG (x is, for example, an integer or a decimal number)), FRA (Future Radio Access), NR (new Radio), New radio access (NX), Future generation radio access (FX), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.17 (WiMAX (registered trademark)), IEEE 802.19 (WiMAX (registered trademark)), IEEE 802.20 (WiMAX (registered trademark)), IEEE 802.21 (Wi-Fi (registered trademark)), IEEE 802.22 (WiMAX (registered trademark)), IEEE 802.23 (WiMAX (registered trademark)), IEEE 802.24 (WiMAX (registered trademark)), IEEE 802.25 (WiMAX (registered trademark)), IEEE 802.26 (WiMAX (registered trademark)), IEEE 802.27 (WiMAX (registered trademark)), IEEE 802.28 (WiMAX (registered trademark)), IEEE 802.29 (WiMAX (registered trademark)), IEEE 802.30 (WiMAX (registered trademark)), IEEE 802.31 (Wi-Fi (registered trademark)), IEEE 802.32 (WiMAX (registered trademark)), IEEE 802.33 (WiMAX (registered trademark)), IEEE 802.34 ( The present invention may be applied to at least one of systems using 802.20, UWB (Ultra-Wide Band), Bluetooth (registered trademark), or other suitable systems, and next-generation systems that are extended, modified, created, or defined based on these systems. The present invention may also be applied to a combination of multiple systems (e.g., a combination of LTE and / or LTE-A with 5G).

[0096] The order of the procedures, sequences, flowcharts, etc. of each aspect / embodiment described herein may be rearranged unless it is consistent. For example, the methods described in this disclosure present elements of various steps using an example order and are not limited to the particular order presented.

[0097] In this specification, a specific operation described as being performed by the base station 10 may be performed by its upper node in some cases. In a network consisting of one or more network nodes having the base station 10, it is clear that various operations performed for communication with the terminal 20 may be performed by at least one of the base station 10 and another network node other than the base station 10 (such as, but not limited to, an MME or an S-GW). Although the above example illustrates a case where there is one other network node other than the base station 10, the other network node may be a combination of multiple other network nodes (such as an MME and an S-GW).

[0098] The information, signals, etc. described in the present disclosure may be output from a higher layer (or a lower layer) to a lower layer (or a higher layer), or may be input / output via multiple network nodes.

[0099] Input and output information may be stored in a specific location (for example, memory) or may be managed using a management table. Input and output information may be overwritten, updated, or added to. Output information may be deleted. Input information may be sent to another device.

[0100] In the present disclosure, the determination may be made by a value represented by one bit (0 or 1), by a Boolean value (true or false), or by a comparison of numerical values ​​(e.g., comparison with a predetermined value).

[0101] Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0102] Software, instructions, information, etc. may also be transmitted or received over a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared, microwave), then these wired and / or wireless technologies are included within the definition of transmission media.

[0103] The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0104] Note that terms described in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of a channel and a symbol may be a signal (signaling). Furthermore, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

[0105] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0106] Furthermore, the information, parameters, etc. described in the present disclosure may be expressed using absolute values, relative values ​​from a predetermined value, or other corresponding information. For example, a radio resource may be indicated by an index.

[0107] The names used for the above-described parameters are not intended to be limiting in any way. Furthermore, the mathematical expressions using these parameters may differ from those explicitly disclosed in this disclosure. The various channels (e.g., PUCCH, PDCCH, etc.) and information elements may be identified by any suitable names, and therefore the various names assigned to these various channels and information elements are not intended to be limiting in any way.

[0108] In the present disclosure, terms such as "base station (BS)," "radio base station," "base station device," "fixed station," "NodeB," "eNodeB (eNB)," "gNodeB (gNB)," "access point," "transmission point," "reception point," "transmission / reception point," "cell," "sector," "cell group," "carrier," and "component carrier" may be used interchangeably. A base station may also be referred to by terms such as a macrocell, a small cell, a femtocell, and a picocell.

[0109] A base station can accommodate one or more (e.g., three) cells. When a base station accommodates multiple cells, the overall coverage area of ​​the base station can be partitioned into multiple smaller areas, and each smaller area can also be provided with communication services by a base station subsystem (e.g., a small indoor base station (RRH: Remote Radio Head)). The terms "cell" or "sector" refer to part or all of the coverage area of ​​a base station and / or base station subsystem that provides communication services within that coverage.

[0110] In the present disclosure, the base station transmitting information to a terminal may be interpreted as the base station instructing the terminal to control or operate based on the information.

[0111] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," and the like may be used interchangeably.

[0112] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other suitable terminology.

[0113] At least one of the base station and the mobile station may be referred to as a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may be a device mounted on a mobile object, the mobile object itself, etc. The mobile object refers to a movable object, and may move at any speed. Naturally, this also includes cases where the mobile object is stationary. Examples of the mobile object include, but are not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcars, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and objects mounted thereon. The mobile object may also be a mobile object that moves autonomously based on an operational command. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile object (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may be a device that does not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0114] Furthermore, a base station in the present disclosure may be read as a user terminal. For example, the aspects / embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between multiple terminals 20 (which may be called, for example, Device-to-Device (D2D) or Vehicle-to-Everything (V2X)). In this case, the terminal 20 may be configured to have the functions of the base station 10 described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, terms such as an uplink channel and a downlink channel may be read as a side channel.

[0115] Similarly, the user terminal in the present disclosure may be read as a base station, in which case the base station may be configured to have the functions of the user terminal described above.

[0116] As used in this disclosure, the terms "determining" and "determining" may encompass a wide variety of actions. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiring (e.g., searching in a table, database, or other data structure), ascertaining, and the like. "Determining" and "determining" may also include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), and the like. Furthermore, "judgment" and "decision" can include regarding resolving, selecting, choosing, establishing, comparing, etc. as having been "judged" or "decided." In other words, "judgment" and "decision" can include regarding some action as having been "judged" or "decided." Furthermore, "judgment (decision)" can be interpreted as "assuming," "expecting," "considering," etc.

[0117] The terms "connected," "coupled," or any variation thereof, refer to any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access." As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using one or more wires, cables, and / or printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

[0118] The reference signal may be abbreviated as RS (Reference Signal) or may be called a pilot depending on the applicable standard.

[0119] As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0120] As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must in some way precede the second element.

[0121] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0122] When the terms "include," "including," and variations thereof are used in this disclosure, these terms are intended to be inclusive, similar to the term "comprising." Furthermore, when the term "or" is used in this disclosure, it is not intended to be an exclusive or.

[0123] In this disclosure, where articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0124] In the present disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "coupled" may also be interpreted in the same way as "different."

[0125] The aspects / embodiments described in this disclosure may be used alone, in combination, or switched depending on the implementation. Notification of predetermined information (e.g., notification that "X is true") is not limited to explicit notification, but may be implicit (e.g., not notifying the predetermined information).

[0126] Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure.

[0127] 10 Base station 110 Transmitter 120 Receiver 130 Setting unit 140 Control unit 20 Terminal 210 Transmitter 220 Receiver 230 Setting unit 240 Control unit 30 Network node 1001 Processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication device 1005 Input device 1006 Output device 2001 Vehicle 2002 Drive unit 2003 Steering unit 2004 Accelerator pedal 2005 Brake pedal 2006 Shift lever 2007 Front wheels 2008 Rear wheels 2009 Axle 2010 Electronic control unit 2012 Information service unit 2013 Communication module 2021 Current sensor 2022 RPM sensor 2023 Tire pressure sensor 2024 Vehicle speed sensor 2025 Acceleration sensor 2026 Brake pedal sensor 2027 Shift lever sensor 2028 Object detection sensor 2029 Accelerator pedal sensor 2030 Driving assistance system unit 2031 Microprocessor 2032 Memory (ROM, RAM) 2033 Communication port (IO port)

Claims

1. A mobile station comprising: a receiving unit that receives from a terminal a first message related to a first signal strength measurement report including a first physical cell identifier; a control unit that recognizes that it cannot be determined that a cell corresponding to the first physical cell identifier belongs to a satellite constellation to which the terminal belongs; and a transmitting unit that transmits to the terminal a second message requesting a report of nearby cells belonging to the satellite constellation to which the terminal belongs, wherein the receiving unit receives from the terminal a third message including a radio frequency channel number used by nearby cells belonging to the satellite constellation to which the terminal belongs; the transmitting unit transmits to the terminal a fourth message requesting a measurement report including a physical cell identifier related to the radio frequency channel number; the receiving unit receives from the terminal a fifth message related to a second signal strength measurement report including a second physical cell identifier; the control unit determines that the cell corresponding to the second physical cell identifier belongs to the satellite constellation to which the terminal belongs; and the control unit selects the cell corresponding to the second physical cell identifier as a handover destination based on the second signal strength measurement report. The transmitter transmits a sixth message requesting a handover to another base station that accommodates a cell corresponding to the second physical cell identifier.

2. The base station according to claim 1, wherein the transmitting unit transmits to the terminal a seventh message requesting a report of broadcast information specifying the second physical cell identifier, the receiving unit receives from the terminal a report of the broadcast information including a satellite constellation identifier of a cell corresponding to the second physical cell identifier, and the control unit associates and stores the second physical cell identifier and the satellite constellation identifier.

3. A terminal having a receiving unit that receives from a base station a first message requesting a report of nearby cells belonging to the currently accommodated satellite constellation; a control unit that searches for nearby cells belonging to the currently accommodated satellite constellation; and a transmitting unit that transmits to the base station a second message including the radio frequency channel number used by the nearby cells belonging to the currently accommodated satellite constellation.

4. A terminal having: a receiving unit that receives, from a first base station, a message requesting a report of broadcast information specifying a physical cell identifier; and a transmitting unit that receives, from a second base station, broadcast information including a satellite constellation identifier of a cell corresponding to the physical cell identifier; and a transmitting unit that transmits a report of the broadcast information including the satellite constellation identifier to the first base station.

5. Receiving a first message relating to a first signal strength measurement report including a first physical cell identifier from a terminal; recognizing that it cannot be determined that the cell corresponding to the first physical cell identifier belongs to the satellite constellation to which the terminal belongs; transmitting a second message to the terminal requesting a report of nearby cells belonging to the satellite constellation to which the terminal belongs; receiving a third message from the terminal including a radio frequency channel number used by a nearby cell belonging to the satellite constellation to which the terminal belongs; transmitting a fourth message to the terminal requesting a measurement report including a physical cell identifier for the radio frequency channel number; receiving a fifth message from the terminal related to a second signal strength measurement report including a second physical cell identifier; determining that the cell corresponding to the second physical cell identifier belongs to the satellite constellation to which the terminal belongs; selecting the cell corresponding to the second physical cell identifier as a handover destination based on the second signal strength measurement report; transmitting a sixth message requesting a handover to another base station accommodating the cell corresponding to the second physical cell identifier. A communication method performed by a network node having the

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