Network node, base station, and communication method

Abstract

This network node comprises: a transmission unit that transmits, to a first network node, a first message that requests a user plane configuration in a second network node; and a reception unit that receives, from the first network node, a second message that includes an identifier of the second network node and that issues a notification indicating that a user plane has been configured in the second network node. The transmission unit transmits, to a base station, a third message that includes the identifier and that requests configuration of the user plane.

Description

Network node, base station, and communication method

[0001] The present invention relates to a network node, a base station, 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 V18.4.0 (2023-12) 3GPP TS 23.228 V18.4.0 (2023-12) 3GPP TR 23.700-29 V0.4.0 (2024-03) 3GPP TS 38.331 V17.7.0 (2024-01) 3GPP TS 38.413 V17.7.0 (2024-01)

[0007] In terminal-satellite-terminal communications, for example, when a satellite constellation is formed using inter-satellite links among low-earth orbit satellites, each satellite is equipped with communication devices such as a base station, a user plane function, and an IMS access gateway. Here, it is necessary to consider a configuration in which multiple satellites share a single user plane function.

[0008] The present invention has been made in view of the above points, and has as its object to enable a plurality of satellites to share one user plane function for communication in a wireless communication system.

[0009] According to the disclosed technique, there is provided a network node having: a transmitter that transmits to a first network node a first message requesting configuration of a user plane at a second network node; and a receiver that receives from the first network node a second message including an identifier of the second network node notifying that a user plane has been configured at the second network node, wherein the transmitter transmits to a base station a third message requesting configuration of a user plane including the identifier.

[0010] According to the disclosed technology, in a wireless communication system, multiple satellites can communicate by sharing one user plane function.

[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 first sequence diagram in an embodiment of the present invention. FIG. 5 is a diagram showing an example of a second sequence diagram in an embodiment of the present invention. FIG. 6 is a diagram showing an example of a third sequence diagram in an embodiment of the present invention. FIG. 7 is a diagram showing an example of a fourth sequence diagram in an embodiment of the present invention. FIG. 8 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. 9 is a diagram showing an example of the functional configuration of a terminal 20 in an embodiment of the present invention. FIG. 10 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.

[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) A procedure for communication in a wireless communication system by sharing one user plane function among a plurality of satellites will be described.

[0034] In this embodiment, it is assumed that a plurality of low-earth orbit satellites (LEOs) equipped with base stations 10, UPFs 30A, and IMS AGWs form a satellite constellation using inter-satellite links (ISLs). Some LEOs are equipped with only base stations 10. Other satellites are equipped with only UPFs 30A and IMS AGWs. Furthermore, N2 intermediaries 30C and N4 intermediaries 30D, which communicate with the base stations 10 and UPFs 30A, respectively, are deployed on the ground as intermediary devices. The base stations 10, terminals 20, and network nodes 30 (30A, 30B, etc.) may also be referred to as communication devices.

[0035] The N2 intermediary 30C performs communication with the base station 10 and communication with the AMF 30F based on the interface (N2) between the base station 10 and the AMF 30F. That is, the N2 intermediary 30C behaves as the AMF 30F with respect to the base station 10, and as the base station 10 with respect to the AMF 30F.

[0036] The N4 intermediary 30D performs communication with the UPF 30A and communication with the SMF 30G based on the interface (N4) between the UPF 30A and the SMF 30G. That is, the N4 intermediary 30D behaves as the SMF 30G with respect to the UPF 30A, and as the UPF 30A with respect to the SMF 30G.

[0037] Furthermore, the intermediary device and the terminal 20 connect to different LEOs depending on the time based on the satellite ephemeris. Here, the satellite ephemeris is information indicating the relationship between the position in the satellite orbit and the time.

[0038] The satellite communications operator mainly prepares the base station 10 and UPF 30A deployed in the LEO, and the intermediate device deployed on the ground, as dedicated equipment for satellite constellation communications.

[0039] On the other hand, mobile communication operators mainly prepare AMF30F and SMF30G, which are network nodes deployed on the ground, as satellite constellation utilization equipment.

[0040] (Network Configuration) In this embodiment, one base station 10 is deployed for each satellite, and one UPF 30A, one IMS AGW, and one inter-satellite cooperation NF are arranged for each of a plurality of satellites.

[0041] (Area Definition) In this embodiment, the orbital plane of a satellite constellation reflecting a tracking area (TA) for a ground-fixed satellite is called an orbital plane tracking area, and is written as a TA orbit. Furthermore, a base station 10 deployed on a satellite covers a specific TA and a specific TA orbit at a specific time. Furthermore, a UPF 30A onboard a satellite covers a UPF SA orbit, which is a specific orbital plane UPF service area (SA), at a specific time. Here, a UPF SA orbit is composed of multiple TA orbits. When covering a specific TA orbit, the base station 10 can connect to a UPF 30A that includes that TA orbit in its UPF SA orbit.

[0042] (IMS PDU Session Establishment Procedure) The IMS PDU session establishment procedure in this embodiment will be described in detail using a sequence diagram. Requests, responses, notifications, and the like transmitted and received in the procedure described below may be referred to as messages (e.g., request messages). For details of existing specifications related to messages transmitted and received in this sequence diagram, see Non-Patent Document 4 and Non-Patent Document 5, etc.

[0043] 4 is a diagram showing an example of a first sequence diagram according to an embodiment of the present invention. The processing of each step will be described below.

[0044] S101: The terminal 20 transmits a request message requesting PDU session establishment to the base station 10. The request message includes information indicating the PDU session establishment request and information related to the Data Network Name (DNN), and is expressed as, for example, ULInformationTransfer(dedicatedNAS-Message(UL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Establishment request), DNN=ims))).

[0045] S102: The base station 10 sends a request message to the N2 intermediary 30C to request establishment of a PDU session. The request message includes information indicating the PDU session establishment request and information about the DNN, and is expressed as, for example, Uplink NAS Transport(NAS-PDU(UL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Establishment request), DNN=ims))).

[0046] S103: The N2 intermediary 30C sends the request message (Uplink NAS Transport) received in S102 to the AMF 30F.

[0047] S104: The AMF 30F recognizes that the request is from a terminal 20 under the control of the satellite constellation (ID (identifier) ​​= aa) based on the base station identifier corresponding to the N2 intermediary 30C.

[0048] S105: The AMF 30F sends a request message requesting establishment of a PDU session to the SMF 30G. The request message includes the satellite constellation identifier (ID=aa) recognized in S104, information indicating the PDU session establishment request, and information related to the DNN, and is expressed as, for example, Nsmf_PDUSession_CreateSMContextRequest(Dnn=ims, SmContextCreateData(n1SmMsg(PDU session establishment request), satellite constellation ID=aa)).

[0049] S106: SMF 30G sends a response message (Nsmf_PDUSession_CreateSMContext response) to the request message received in S104 to AMF 30F.

[0050] S107: Based on the satellite constellation identifier (ID=aa) included in the message received in S105, SMF 30G selects N4 intermediary 30D as the destination of the request message requesting PDU session establishment.

[0051] S108: SMF 30G decides to transmit the identifier (PDU session ID) of the PDU session to facilitate operation within the satellite.

[0052] S109: The SMF 30G sends a request message (PFCP Session Establishment Request) to the N4 intermediary 30D to request establishment of a PDU session. The request message includes a PDU session identifier (PDU session ID). That is, the request message requests the N4 intermediary 30D to set up a user plane in the UPF 30A.

[0053] S110: The N4 intermediary 30D selects a UPF 30A to connect to using a list created based on the satellite ephemeris. For example, the N4 intermediary 30D selects a UPF 30A to connect to at the current time based on a list showing the relationship between connectable time periods (specified by, for example, start and end times) and connectable UPF 30A candidates.

[0054] S111: The N4 intermediary 30D transmits the request message (PFCP Session Establishment request) received in S109 to the UPF 30A. The request message includes the PDU session identifier (PDU session ID).

[0055] S112: The UPF 30A transmits to the N4 intermediary 30D a response message (PFCP Session Establishment response) in response to the request message received in S111.

[0056] S113: The N4 intermediary 30D transmits to the SMF 30G a response message (PFCP Session Establishment response) in response to the request message received in S109. That is, the response message notifies the SMF 30G that the user plane has been set up in the UPF 30A.

[0057] S114: SMF 30G sets the pre-stored IP (Internet Protocol) address (P-CSCF address = bb) of a special P-CSCF deployed on the ground that can handle the satellite IMS AGW as the P-CSCF address of ePCO (extended Protocol Configuration Options).

[0058] S115: When the SMF 30G assigns an IP address to the terminal 20 that uses a satellite, the SMF 30G assigns it from the IP address range used by the satellite constellation with the identifier (ID=aa) received in S105.

[0059] S116: The SMF 30G decides to transmit the identifier (Node ID) of the UPF 30A to the base station 10. After transmission, the SMF 30G may delete the identifier (Node ID).

[0060] S117: The SMF 30G transmits a message including information indicating acceptance of the PDU session establishment request to the AMF 30F. The message also includes the IP address of the P-CSCF set in S115 (P-CSCF address=bb) and the identifier (Node ID) of the UPF 30A determined in S116, and is expressed as, for example, Namf_Communication_N1N2MessageTransfer (N1N2MessageTransferReqData (n1MessageContainer(PDU Session Establishment accept(Extended protocol configuration options(P-CSCF address=bb))), n2InfoContainer(PDU Session Resource Setup Request Transfer(UPF Node ID)))).

[0061] S118: The AMF 30F transmits a message including information indicating acceptance of the PDU session establishment request to the N2 intermediary 30C. The message also includes the IP address of the P-CSCF (P-CSCF address=bb) and the identifier (Node ID) of the UPF 30A received in S117, and is expressed as, for example, PDU Session Resource Setup Request(NAS-PDU(DL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Establishment accept(Extended protocol configuration options(P-CSCF address=bb))))), PDU Session Resource Setup Request List(PDU Session Resource Setup Request Transfer(UPF Node ID))).

[0062] S119: The N2 intermediary 30C transmits the message (PDU Session Resource Setup Request) received in S118 to the base station 10.

[0063] S120: The base station 10 extracts and stores the identifier (Node ID) of the UPF 30A included in the message received in S119.

[0064] S121: The base station 10 transmits a message including information indicating acceptance of the PDU session establishment request to the terminal 20. The message also includes the IP address of the P-CSCF (P-CSCF address=bb) and the identifier (Node ID) of the PF 30A received in S119, and is expressed as, for example, RRCReconfiguration(dedicatedNAS-Message(DL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Establishment accept(Extended protocol configuration options(P-CSCF address=dd)))))).

[0065] (Handover Procedure) The handover procedure will now be described. If the source base station determines that the UPF currently connected to the destination base station and the source base station can be connected for a while after the start of handover, it determines that UPF switching is not necessary during handover and executes a handover procedure without UPF switching. Here, a procedure based on the Xn handover procedure is introduced to keep user plane path switching within the satellite constellation. The base station obtains in advance from the satellite operation system a list of pairs of base station identifier, time, and orbital plane tracking area it covers (list of [base station ID, (available) time, covered TA orbit]), and a list of pairs of UPF identifier, time, and orbital plane UPF service area it covers (list of [UPF ID, (available) time, covered UPF SA orbit]).

[0066] On the other hand, if such a determination is not possible, the source base station determines that UPF switching is also necessary during handover, and when the handover is initiated, sends a UPF switching indication to the destination base station and executes the handover procedure involving UPF switching.

[0067] The handover procedure will be explained below using a sequence diagram.

[0068] (Handover Procedure Without UPF Switching) Details of the handover procedure without UPF switching will be described using a sequence diagram. In this procedure, a handover is executed from a source LEO including the base station 10A, UPF 30M, and inter-satellite cooperation NF 30O to a destination LEO including the base station 10B. That is, an intra-satellite constellation handover (HO) is executed between the source LEO and the destination LEO, which can share the same UPF. Figure 5 is a diagram showing an example of a second sequence diagram in an embodiment of the present invention. The processing of each step will be described below.

[0069] S201: The base station 10A stores a list (list of [base station ID, time, covered TA orbit]) of pairs of base station identifiers, time, and covered orbital plane tracking areas for the base station itself and other surrounding base stations. The base station 10B also stores information about other surrounding UPFs, a list (list of [UPF ID, time, covered UPF SA orbit]) of pairs of UPF identifiers, time, and covered orbital plane UPF service areas.

[0070] S202: The base station 10A acquires and stores the identifier (UPF Node ID) of the UPF to which the PDU session is currently connected.

[0071] S203: The base station 10A determines whether to perform handover of the terminal 20 and to which base station 10B the terminal 20 will be moved.

[0072] S204: Based on the two lists stored in S201, the base station 10A determines whether the destination base station 10B and the UPF 30M to which the base station 10A is currently connected can be connected for, for example, a predetermined time from the start of handover. If the base station 10A can make this determination, it further determines to execute handover of the terminal 20 without UPF switching.

[0073] S205: The base station 10B stores address information of the inter-satellite cooperation NF that controls each UPF. The address information is, for example, a list of pairs of a UPF identifier and address information of the inter-satellite cooperation NF that controls the UPF.

[0074] S206: The inter-satellite cooperation NF 30R stores address information of the inter-satellite cooperation NF corresponding to the identifier (UPF Node ID) of each UPF. The address information is, for example, a list of pairs of the identifier of the UPF and the address information of the inter-satellite cooperation NF that controls the UPF.

[0075] S207: In the source LEO, uplink user plane data (hereinafter referred to as UL user data) is being transmitted on the route from the terminal 20 to the base station 10A and on the route from the base station 10A to the UPF 30M. Also, downlink user plane data (hereinafter referred to as DL user data) is being transmitted on the route from the base station 10A to the terminal 20 and on the route from the UPF 30M to the base station 10A.

[0076] S208: The base station 10A transmits a request message (handover request) requesting a handover to the base station 10B. The request message includes a PDU session identifier, information indicating that the handover is within the satellite constellation, and an identifier (UPF Node ID) of the UPF 30M in the source LEO, and is expressed as, for example, Handover Request (PDU session ID, satellite constellation HO, source UPF Node ID). In other words, the request message does not include information indicating that a UPF switch is required (that a switch is involved).

[0077] S209: Based on the information indicating that the handover is within the satellite constellation, which is included in the request message received in S208, the base station 10B decides to execute processing related to the intra-satellite constellation HO (for example, processing related to the inter-satellite cooperation NF and processing related to the sequence number of user data (assignment of UL GTP-U SN)).

[0078] S210: The base station 10B transmits to the base station 10A a response message (Handover Request Acknowledge) in response to the request message received in S209.

[0079] S211: The base station 10A transmits to the terminal 20 a request message (RRCReconfiguration (=Handover Command)) requesting the execution of handover.

[0080] S212: The base station 10A transmits a message (SN status transfer) related to the status of the sequence number (SN) to the base station 10B. The message includes the status of the sequence number of the GTP-U (GPRS (General Packet Radio Service) Tunnel Protocol - User Plane) in the UL (UL GTP-U SN status).

[0081] S213: Paths for DL ​​user data are set between the UPF 30M and the base station 10A, and between the base station 10A and the base station 10B. Here, the base station 10B buffers the DL user data without forwarding it.

[0082] S214: The terminal 20 transmits a message (RRCReconfigurationComplete) to the base station 10B notifying the completion of the handover.

[0083] S215: From the state of S213, buffering of DL user data at the base station 10B is released, and a route is set between the base station 10B and the terminal 20. Also, routes are set between the terminal 20 and the base station 10B and between the base station 10B and the UPF 30M for UL user data.

[0084] The process following S215 will be described. Fig. 6 is a diagram showing an example of a third sequence diagram according to an embodiment of the present invention. The process of each step will be described below.

[0085] S216: Since the information contained in the request message received in S208 of FIG. 5 does not include information indicating the need for UPF switching, the base station 10B decides to use the UPF 30M of the source LEO, which is specified by the identifier (UPF Node ID) in the request message.

[0086] S217: The base station 10B identifies the inter-satellite cooperation NF 30O that controls the UPF 30M of the source LEO.

[0087] S218: The base station 10B transmits a notification message to the inter-satellite cooperation NF300 to notify the event. The notification message includes information indicating that the handover confirmation (received in S214) has been received, the value (bb) of DL NG-U UP TNL Information which is termination point information on the base station's own side when receiving DL user data, the identifier (UPF Node ID) of the UPF 30M in the source LEO, and the PDU session identifier. The notification message also requests path switching of the DL user data in the UPF 30M. The notification message is expressed as, for example, event notification (handover confirm received, DL NG-U UP TNL Information=bb, source UPF Node ID, PDU session ID).

[0088] S219: Based on the information contained in the notification message received in S218, the inter-satellite cooperation NF300 confirms that the identifier (UPF Node ID) of the source UPF 30M corresponds to the UPF managed by its own device, and determines that the handover does not involve UPF switching.

[0089] S220: The inter-satellite cooperation NF 30O transmits a request message (PFCP Session Modification request) to the UPF 30M requesting an update of settings related to the forwarding of DL user data. The request message includes a termination identifier (TEID (= bb)) set by the destination base station 10B and a PDU session identifier as setting information related to a forwarding action rule (FAR) for DL. For example, the request message is expressed as PFCP Session Modification request (FAR = destination gNB TEID bb, PDU session ID).

[0090] S221: The UPF 30M transmits a response message (PFCP Session Modification response) to the request message received in S220 to the inter-satellite cooperation NF 30O.

[0091] S222: The UPF 30M updates the settings related to the transfer of DL user data based on the information included in the request message received in S220. That is, the transfer of DL user data from the UPF 30M to the base station 10A is deleted from the state of S215 in Fig. 5 .

[0092] S223: The base station 10B transmits a request message (Path Switch Request) to the N2 intermediary 30C to request a path switch. The request message includes information indicating the switch of the C-plane termination point to the base station 10B, but does not include information related to the user plane.

[0093] S224: The N2 intermediary 30C transmits to the base station 10B a response message (Path Switch response, Path Switch Request Acknowledge) in response to the request message received in S223.

[0094] S225: The base station 10B transmits a request message (UE Context release) to the base station 10A to request the release of the context of the terminal 20.

[0095] (Handover Procedure with UPF Switching) Details of the handover procedure with UPF switching will be described using a sequence diagram. In this procedure, handover is executed from a source LEO including a base station 10A, a UPF 30M, and an inter-satellite cooperation NF 30O to a destination LEO including a base station 10B, a UPF 30P, and an inter-satellite cooperation NF 30R. Fig. 7 is a diagram showing an example of a fourth sequence diagram in the embodiment of the present invention. The processing of each step in Fig. 7 will be described below.

[0096] S301: The base station 10A stores a list (list of [base station ID, time, covered TA orbit]) of pairs of base station identifiers, time, and covered orbital plane tracking areas for the base station itself and other surrounding base stations. The base station 10B also stores information about other surrounding UPFs, a list (list of [UPF ID, time, covered UPF SA orbit]) of pairs of UPF identifiers, time, and covered orbital plane UPF service areas.

[0097] S302: The base station 10A acquires and stores the identifier (UPF Node ID) of the UPF to which the PDU session is currently connected.

[0098] S303: The base station 10A determines whether to perform handover of the terminal 20 and to which base station 10B the terminal 20 will be moved.

[0099] S304: Based on the two lists stored in S301, the base station 10A determines whether the destination base station 10B and the UPF 30M to which the base station 10A is currently connected can be connected for, for example, a predetermined time from the start of handover. If the base station 10A cannot make this determination, it determines to execute handover of the terminal 20, which involves UPF switching.

[0100] S305: The base station 10B stores a list (list of [base station ID, time, covered TA orbit]) of pairs of base station identifiers, time, and covered orbital plane tracking areas for the base station itself and other surrounding base stations. The base station 10B also stores information about other surrounding UPFs, including a list (list of [UPF ID, time, covered UPF SA orbit]) of pairs of UPF identifiers, time, and covered orbital plane UPF service areas.

[0101] S306: The base station 10B stores address information of the inter-satellite cooperation NF that controls each UPF. The address information is, for example, a list of pairs of a UPF identifier and address information of the inter-satellite cooperation NF that controls the UPF.

[0102] S307: The inter-satellite cooperation NF 30R stores address information of the inter-satellite cooperation NF corresponding to the identifier (UPF Node ID) of each UPF. The address information is, for example, a list of pairs of the identifier of the UPF and the address information of the inter-satellite cooperation NF that controls the UPF.

[0103] S308: In the source LEO, uplink user plane data (hereinafter referred to as UL user data) is being transmitted on the route from the terminal 20 to the base station 10A and on the route from the base station 10A to the UPF 30M. Also, downlink user plane data (hereinafter referred to as DL user data) is being transmitted on the route from the base station 10A to the terminal 20 and on the route from the UPF 30M to the base station 10A.

[0104] S309: The base station 10A transmits a request message (handover request) requesting a handover to the base station 10B. The request message includes a PDU session identifier, information indicating that the handover is within the satellite constellation, an identifier (UPF Node ID) of the UPF 30M in the source LEO, and information indicating that a UPF switch is required (that a switch is involved), and is expressed as, for example, Handover Request (PDU session ID, satellite constellation HO, source UPF Node ID, UPF switch required).

[0105] S310: The base station 10A starts a timer that detects whether the time limit for receiving a response to the request sent in S309 has expired (timeout). The time limit for the timer to detect a timeout may be set to, for example, a time limit longer than that for a normal handover, in order to limit the time when the cause of the handover is a satellite movement cause.

[0106] S311: Based on the information indicating that UPF switching is necessary contained in the request message received in S309, the base station 10B recognizes that the source base station 10A has determined that UPF switching is necessary.

[0107] S312: The base station 10B selects a destination UPF 30P based on the information about the TAorbit and UPF SAorbit stored in the base station 10B described in S305, and identifies the address of the inter-satellite cooperation NF 30R that controls the selected UPF 30P.

[0108] S313: The base station 10B transmits a notification message to the inter-satellite cooperation NF 30R to notify the event. The notification message includes information indicating that UPF switching is necessary, an identifier (UPF Node ID) of the UPF 30M in the source LEO, and a PDU session identifier. That is, the notification message requests switching of the UPF 30M. The notification message is expressed as, for example, an event notification (Handover Request (UPF switching required, source UPF Node ID, PDU session ID)).

[0109] S314: The base station 10B waits for an event notification to be transmitted from the inter-satellite link NF 30R.

[0110] S315: The inter-satellite link NF 30R transmits an event notification to the base station 10B to notify that UPF switching will start.

[0111] S316: The base station 10B waits for an event notification that notifies completion of UPF switching, which is transmitted from the inter-satellite cooperation NF 30R.

[0112] S317: The inter-satellite cooperation NF 30R transmits to the UPF 30P a first request message related to UL user data and a second request message related to DL user data as request messages (PFCP Session Establishment requests) requesting establishment of a path for transferring UL user data and DL user data between UPFs. The first request message and the second request message include setting information related to a packet detection rule (PDR) and setting information related to a forwarding action rule (FAR). The setting information related to the PDR in the first request message and the second request message includes a setting related to the interface between the UPF 30M and the UPF 30P. Furthermore, the setting information related to the FAR in the first request message and the second request message includes information indicating that buffering is set to ON.

[0113] S318: The UPF 30P transmits a first response message related to UL user data and a second response message related to DL user data to the inter-satellite cooperation NF 30R as response messages (PFCP Session Establishment responses) to the request message received in S317. The first response message includes an identifier (UL TEID) related to the termination point for UL user data in the destination UPF 30P as setting information related to the PDR. The second response message includes an identifier (DL TEID) related to the termination point for DL ​​user data in the destination UPF 30P as setting information related to the PDR.

[0114] S319: The inter-satellite cooperation NF 30R identifies the inter-satellite cooperation NF 30O corresponding to the UPF 30M based on the identifier (UPF Node ID) of the UPF 30M in the source LEO received in S313, and acquires the address of the inter-satellite cooperation NF 30O.

[0115] S320: The inter-satellite cooperation NF 30R transmits a request message (UL / DL forwarding path setting request) to the inter-satellite cooperation NF 30O, requesting execution of settings related to the forwarding paths of UL user data and DL user data. The request message includes the UL TEID of the UPF 30P, which is the destination, the DL TEID of the UPF 30P, setting information related to the PDR, and a PDU session identifier. Here, the setting information related to the PDR is information (null information) that does not include any information to be set. In other words, after preparation for UPF switching is executed based on the information included in the request message, UPF switching is executed.

[0116] According to the above-described embodiment, in a wireless communication system, a plurality of satellites can communicate by sharing one user plane function.

[0117] (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.

[0118] <Base Station 10 and Network Node 30> Fig. 8 is a diagram showing an example of the functional configuration of the base station 10 and the network node 30. As shown in Fig. 8, 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. 8 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] <Terminal 20> Fig. 9 is a diagram showing an example of the functional configuration of the terminal 20. As shown in Fig. 9, 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. 9 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, the communication device that becomes the resource holder 20 may have the same functional configuration as the terminal 20.

[0123] 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.

[0124] The setting unit 230 stores various pieces of setting information received from the network node 30 by the receiving unit 220 in a storage device, and reads them out from the storage device as needed. The setting unit 230 also stores setting information that is set in advance.

[0125] 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.

[0126] (Hardware Configuration) The block diagrams (FIGS. 8 and 9) 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.

[0127] 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.

[0128] 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. 10 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] The processor 1001 also 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. 8 may be implemented by a control program stored in the storage device 1002 and running on the processor 1001. For example, the control unit 240 of the terminal 20 shown in FIG. 9 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] The input device 1005 is an input device (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives 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).

[0137] 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.

[0138] 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.

[0139] Fig. 11 shows an example configuration of a vehicle 2001. As shown in Fig. 11, 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.

[0140] 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.

[0141] 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).

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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.

[0149] 1. A network node comprising: a transmitter that transmits, to a first network node, a first message requesting configuration of a user plane at a second network node; and a receiver that receives, from the first network node, a second message notifying that a user plane has been configured at the second network node, the second message including an identifier of the second network node, wherein the transmitter transmits, to a base station, a third message requesting configuration of a user plane, the third message including the identifier. (Supplementary Item 2) A base station comprising: a receiver that receives, from a base station, a first message requesting execution of the handover, the first message including information indicating that the handover is within a satellite constellation and an identifier of the first network node, but not information indicating that the handover involves switching of the first network node; and a controller that identifies a second network node that controls the first network node; and a transmitter that transmits, to the second network node, a second message requesting path switching of downlink user data at the first network node, the second message including termination point information for reception of downlink user data at the base station.(Supplementary Item 3) A base station comprising: a control unit that stores a first list of pairs of base station identifiers, available times, and orbital plane tracking areas of the base station itself and other surrounding base stations; and a second list of pairs of identifiers, available times, and orbital plane network node service areas of surrounding network nodes having user plane functionality; a receiving unit that receives from a base station a first message requesting execution of the handover, the first message including information indicating that the handover is within a satellite constellation, an identifier of a first network node having user plane functionality, and information indicating that a switch of the first network node is involved; a control unit that selects a second network node having user plane functionality as a destination based on the first list and the second list, and identifies a third network node that controls the second network node; and a transmitting unit that transmits to the third network node a second message requesting a switch of the second network node, the second message including an identifier of a fourth network having user plane functionality as a source of the handover. (Supplementary Item 4) A network node comprising: a control unit that stores, for a first network node having a user plane function, a list of pairs of an identifier of the first network node and an identifier of a network node that controls the first network node; a receiving unit that receives from a base station a first message requesting switching of the second network node, the first message including an identifier of a second network node having a user plane function of a source; a control unit that identifies a third network node that controls the second network node; and a transmitting unit that transmits to the third network node a second message requesting execution of switching preparation of the second network node.(Supplementary Item 5) A base station comprising: a first list of pairs of base station identifiers, available times, and orbital plane tracking areas for the base station itself and surrounding base stations; and a second list of pairs of identifiers, available times, and orbital plane network node service areas for surrounding network nodes having a user plane function; a controller that stores an identifier of a first network node having a user plane function to which the terminal is currently connected; executes handover of a terminal and determines a destination base station; and a transmitter that determines, based on the first list and the second list, that the destination base station and the first network node are connectable for a predetermined time from the start of handover; and, if the determination is not possible, transmits to the destination base station a message requesting execution of the handover, the message including information indicating that the handover is within a satellite constellation, the identifier of the first network node, and information indicating that switching of the first network node is involved. (Supplementary clause 6) A communication method executed by a network node, comprising: a step of transmitting, to a first network node, a first message requesting configuration of a user plane at a second network node; a step of receiving, from the first network node, a second message notifying that a user plane has been configured at the second network node, the second message including an identifier of the second network node; and a step of transmitting, to a base station, a third message requesting configuration of a user plane, the third message including the identifier.

[0150] Any of Supplementary Items 1 to 6 allows a plurality of satellites to share one user plane function for communication in a wireless communication system.

[0151] (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.

[0152] 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.

[0153] 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).

[0154] 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.

[0155] 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).

[0156] 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.

[0157] 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.

[0158] In the present disclosure, the determination may be made based on a value represented by one bit (0 or 1), a Boolean value (true or false), or a numerical comparison (e.g., comparison with a predetermined value).

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0164] Furthermore, the information, parameters, etc. described in the present disclosure may be expressed using absolute values, may be expressed using relative values ​​from a predetermined value, or may be expressed using other corresponding information. For example, a radio resource may be indicated by an index.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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.

[0169] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," and the like may be used interchangeably.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] 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.

[0176] The reference signal may be abbreviated as RS (Reference Signal) or may be called a pilot depending on the applicable standard.

[0177] 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."

[0178] 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.

[0179] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0180] 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.

[0181] 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.

[0182] 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."

[0183] 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).

[0184] 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.

[0185] 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 network node comprising: a transmitter that transmits to a first network node a first message requesting the establishment of a user plane at a second network node; and a receiver that receives from the first network node a second message including an identifier of the second network node notifying that a user plane has been established at the second network node, wherein the transmitter transmits to a base station a third message including the identifier requesting the establishment of a user plane.

2. A base station comprising: a receiving unit that receives, from a base station, a first message requesting execution of the handover, the first message including information indicating that the handover is within a satellite constellation and an identifier of a first network node, but not including information indicating that the handover involves switching of the first network node; a receiving unit that receives, from a terminal, a first message notifying completion of the handover; a control unit that identifies a second network node that controls the first network node; and a transmitting unit that transmits, to the second network node, a second message requesting path switching of downlink user data of the first network node, the second message including termination point information for receiving downlink user data at the base station.

3. A base station comprising: a control unit that stores a first list of pairs of base station identifiers, available times, and orbital plane tracking areas for the base station itself and other surrounding base stations; and a second list of pairs of identifiers, available times, and orbital plane network node service areas for surrounding network nodes having user plane functionality; a receiving unit that receives from the base station a first message requesting execution of the handover, the first message including information indicating that the handover is within a satellite constellation, an identifier of a first network node having user plane functionality, and information indicating that a switch of the first network node is involved; a control unit that selects a second network node having user plane functionality as a destination based on the first list and the second list, and identifies a third network node that controls the second network node; and a transmitting unit that transmits to the third network node a second message requesting a switch of the second network node, the second message including an identifier of a fourth network having user plane functionality as a source of the handover.

4. A network node comprising: a control unit that stores, for a first network node having a user plane function, a list of pairs of an identifier of the first network node and an identifier of a network node that controls the first network node; a receiving unit that receives from a base station a first message requesting switching of the second network node, the first message including an identifier of a second network node having a user plane function of a source of movement; a control unit that identifies a third network node that controls the second network node; and a transmitting unit that transmits to the third network node a second message requesting the second network node to perform switching preparation.

5. A base station having: a first list of pairs of base station identifiers, available times, and orbital plane tracking areas for the device itself and surrounding base stations; and a second list of pairs of identifiers, available times, and orbital plane network node service areas for surrounding network nodes with user plane functionality; a control unit that stores the identifier of a first network node with user plane functionality to which the device is currently connected; executes handover of a terminal and determines a destination base station; and a control unit that determines, based on the first list and the second list, whether the destination base station and the first network node can connect for a predetermined time from the start of handover; and a transmission unit that, if the determination is not possible, sends to the destination base station a message requesting execution of the handover, the message including information indicating that the handover is within a satellite constellation, the identifier of the first network node, and information indicating that switching of the first network node is required.

6. A communication method executed by a network node, comprising: sending a first message to a first network node requesting configuration of a user plane at a second network node; receiving a second message from the first network node notifying that a user plane has been configured at the second network node, the second message including an identifier of the second network node; and sending a third message to a base station requesting configuration of a user plane, the third message including the identifier.

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