Network node, base station, terminal, and communication method

Abstract

This network node includes a receiving unit that receives, from a first network node, a first message requesting path switching accompanying a change in base station, the first message including a satellite identifier of a satellite on which the migration destination base station is located, a control unit that recognizes that the satellite on which the migration origin base station is located is different from the satellite on which the migration destination base station is located, and a transmitting unit that transmits, to a second network node, a second message inquiring whether or not to switch an ULCL (Uplink Classifier) and a local user plane function, wherein: the receiving unit receives a third message, transmitted from the second network node, approving the switching of the ULCL and the local user plane function; the control unit sets the migration destination ULCL and the migration destination local user plane function; and the transmitting unit transmits, to the second network node, a fourth message notifying that the switching of the ULCL and the local user plane function is complete.

Description

Network node, base station, terminal, and communication method

[0001] The present invention relates to a network node, 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 V18.0.0 (2023-12) 3GPP TS 38.413 V18.0.0 (2023-12) 3GPP TS 23.502 V18.7.0 (2024-06)

[0007] 3GPP is considering using PANI (P-Access-Network-Info), a Session Initiation Protocol (SIP) header, to determine whether to route voice media over the satellite constellation or via terrestrial route in satellite constellation communications. The terminal sets the NR cell identifier and other information in PANI based on the received system information.

[0008] However, if the terminal performs a handover during voice communication, it cannot obtain the NR cell identifier of the handover destination and send the updated PANI to the P-CSCF, so the P-CSCF cannot correctly perform routing using the PANI after the handover.

[0009] The present invention has been made in view of the above-mentioned points, and has as its object to correctly execute routing after handover in a wireless communication system using a satellite.

[0010] According to the disclosed technology, there is provided a network node comprising: a receiver that receives from a first network node a first message requesting route switching accompanying a change of base station, the message including a satellite identifier of a satellite on which a destination base station is located; a controller that recognizes that the satellite on which the source base station is located is different from the satellite on which the destination base station is located; and a transmitter that transmits to a second network node a second message inquiring whether or not to switch an Uplink Classifier (ULCL) and a local user plane function, wherein the receiver receives a third message transmitted from the second network node agreeing to switch the ULCL and the local user plane function, the controller sets the destination ULCL and the local user plane function, and the transmitter transmits to the second network node a fourth message notifying completion of switchover of the ULCL and the local user plane function.

[0011] According to the disclosed technology, routing can be correctly performed after handover in a wireless communication system using a satellite.

[0012] 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 fifth sequence diagram in an embodiment of the present invention. FIG. 8 is a diagram showing an example of a sixth sequence diagram in an embodiment of the present invention. FIG. 9 is a diagram showing an example of a seventh sequence diagram in an embodiment of the present invention. FIG. 10 is a diagram showing an example of a tenth sequence diagram in an embodiment of the present invention. FIG. 11 is a diagram showing an example of an eleventh sequence diagram in an embodiment of the present invention. FIG. 12 is a diagram showing an example of a twelfth sequence diagram in an embodiment of the present invention. FIG. 13 is a diagram showing an example of a thirteenth sequence diagram in an embodiment of the present invention. FIG. 14 is a diagram showing an example of a fifteenth sequence diagram in an embodiment of the present invention. FIG. 16 is a diagram showing an example of a sixteenth sequence diagram in an embodiment of the present invention. FIG. 17 is a diagram showing an example of a seventeenth sequence diagram in an embodiment of the present invention. FIG. 18 is a diagram showing an example of an eighteenth sequence diagram in an embodiment of the present invention. Fig. 10 is a diagram showing an example of a nineteenth sequence diagram in an embodiment of the present invention. Fig. 11 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. 12 is a diagram showing an example of the functional configuration of a terminal 20 in an embodiment of the present invention. Fig. 13 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. 14 is a diagram showing an example of the configuration of a vehicle 2001 in an embodiment of the present invention.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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:

[0026] 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.

[0027] 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.

[0028] The S-CSCF (Serving-Call Session Control Function) is a network node 30 having functions related to session control for the UE.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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).

[0033] 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.

[0034] In this embodiment, it is assumed that a base station, an uplink classifier (ULCL), and multiple low-earth orbit satellites (LEOs) equipped with UPFs form a satellite constellation using inter-satellite links (ISLs). The ULCL has the function of selectively allocating uplink traffic between N9 interfaces.

[0035] Satellite communications operators prepare dedicated equipment for satellite constellation communications, primarily base stations, ULCLs, and UPFs deployed in LEO, and intermediate devices deployed on the ground that communicate with satellite-based devices, while mobile communications operators prepare network nodes, such as AMFs and SMFs, deployed on the ground, as satellite constellation utilization equipment.

[0036] In this embodiment, a procedure for correctly executing routing after handover in a wireless communication system using a satellite will be described.

[0037] In 3GPP, the use of PANI (P-Access-Network-Info), a Session Initiation Protocol (SIP) header, is being considered to determine whether voice media should be routed over the satellite constellation or via terrestrial route in satellite constellation communications. Based on the received system information, the terminal sets the NR cell identifier (ID), MCC (Mobile Country Code), MNC (Mobile Network Code), and TAC (Tracking Area Code) in the PANI.

[0038] However, if a terminal performs a handover during voice communication, it cannot acquire the NR cell identifier of the handover destination and send the updated PANI to the P-CSCF. Therefore, the P-CSCF cannot correctly perform routing using the PANI after the handover. Here, when acquiring the destination NR cell ID, it is assumed that a SIP re-INVITE will be sent due to the change in PANI, so it is necessary to acquire the destination NR cell ID at an appropriate time.

[0039] Therefore, in this embodiment, after the SMF configures the target ULCL and the target local UPF and when the P-CSCF recognizes the need for IMS AGW configuration, the SMF sends a message to the base station via the AMF requesting NR cell ID reconfirmation. The base station reconfigures the terminal to check the system information (SIB).

[0040] The details of the processing in this embodiment will be explained below using sequence diagrams. Requests, responses, notifications, etc. sent and received in the procedures shown below may be called messages (e.g., request messages). For details of existing specifications related to messages sent and received in this sequence diagram, see Non-Patent Documents 4-6, etc.

[0041] On the originating side, AMF 30A, SMF 30B, PCF 30C, P-CSCF 30G, S-CSCF 30H, HSS 30J, remote IMS AGW 30FR, and remote UPF (R-PSA1) 30D1R, which is the first termination point of the PDU session (PDU Session Anchor 1, PSA1), are deployed on the ground. Meanwhile, base station 10A, ULCL 30E, local IMS AGWFL, and local UPF (L-PSA2) 30D2L, which is the second termination point (PSA2) of the PDU session, are deployed on the satellite to which terminal 20A connects.

[0042] Similarly, on the terminating side, AMF 30A2, SMF 30B2, PCF 30C2, P-CSCF 30G2, S-CSCF 30H2, HSS 30J2, remote IMS AGW 30FR2, and remote UPF (R-PSA3) 30D3R, which is the third termination point (PSA3) of the PDU session, are deployed on the ground. Meanwhile, base station 10B, ULCL 30E2, local IMS AGWFL2, and local UPF (L-PSA4) 30D4L, which is the fourth termination point (PSA4) of the PDU session, are deployed on the satellite to which terminal 20B connects.

[0043] In this sequence, after satellite-based voice communication is established between terminal 20A, which is the calling terminal, and terminal 20B, which is the called terminal, handover is performed by switching the satellite connected to terminal 20A. Here, the destination satellite is equipped with base station 10C, ULCL 30E3, local IMS AGWFL 3, and local UPF (L-PSA5) 30D5L3, which is the fifth termination point (PSA5) of the PDU session. Also, UPF may be expressed as a termination point of a PDU session; for example, UPF (R-PSA1) 30D1R may be expressed as UPF 30D1R or PSA1.

[0044] (NG Setup and IMS PDU Session Establishment) The procedures for NG setup and IMS PDU session establishment will be described. For the NG setup procedure in the existing specifications, refer to section 8.7.1 of Non-Patent Document 5. For the PDU session establishment procedure in the existing specifications, refer to section 4.3.2 of Non-Patent Document 6. Figure 4 shows an example of a first sequence diagram in an embodiment of the present invention. Below, the processing of each step of NG setup will be described.

[0045] S101: The base station 10A sends an NG Setup request to the AMF 30A, which includes a satellite constellation ID and a satellite identifier (satellite ID).

[0046] S102: The AMF 30A transmits an NG Setup response to the base station 10A.

[0047] As a result, an interface is set between the base station 10A and the AMF 30A. Next, the processing of each step of establishing an IMS PDU session will be described with reference to FIG.

[0048] S201: The terminal 20A transmits a request message requesting PDU session establishment to the base station 10A. 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))).

[0049] S202: The base station 10A transmits a request message requesting PDU session establishment to the AMF 30A. The request message includes information indicating the PDU session establishment request and information related to 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))).

[0050] S203: AMF 30A determines that base station 10A on the satellite sent the request message based on the previously recognized association between the transport layer settings and the identifier of the source base station, and the transport layer settings of the request message received in S202. Furthermore, AMF 30A determines based on the identifier of base station 10A on the satellite that the request is from terminal 20A under the control of satellite constellation (ID (identifier) ​​= aa), i.e., that terminal 20 is accommodated in the satellite constellation, and stores the satellite constellation ID and the satellite identifier (satellite ID) in its own device.

[0051] S204: AMF 30A sends a request message (Nsmf_PDUSession_CreateSMContext request) requesting establishment of a PDU session to SMF 30B. The request message includes a satellite constellation ID and a satellite ID, and is expressed as, for example, Nsmf_PDUSession_CreateSMContext request(SmContextCreateData(Dnn=ims, n1SmMsg(PDU session establishment request), satellite constellation ID=aa, satellite ID)).

[0052] S205: SMF 30B sends a response message (Nsmf_PDUSession_CreateSMContext response) to AMF 30A in response to the request message received in S204.

[0053] S206: SMF 30B sends a request message (Npcf_SMPolicyControl_Create request) to PCF 30C requesting the determination and transmission of a policy for the PDU session. This request message includes a satellite constellation ID and a satellite ID, and is expressed as, for example, Npcf_SMPolicyControl_Create request (SmPolicyContextData(dnn=ims, satellite constellation ID=aa, satellite ID)).

[0054] S207: The PCF 30C sends to the SMF 30B a response message (Npcf_SMPolicyControl_Create response) in response to the request message received in S206.

[0055] S208: SMF30B sends a request message (PFCP Session Establishment request) to UPF30D1R to establish a user data transfer path.

[0056] S209: UPF 30D1R sends a response message (PFCP Session Establishment response) to the request message received in S208 to SMF 30B.

[0057] S210: SMF 30B stores the IP address (= bb) of P-CSCF 30G, which is a (terrestrially deployed) satellite P-CSCF. SMF 30B sets the IP address (= bb) as the P-CSCF address of ePCO (extended Protocol Configuration Option).

[0058] S211: SMF 30B sends a message (Namf_Communication_N1N2MessageTransfer request) including information indicating acceptance of the PDU session establishment request to AMF 30A. The message includes a P-CSCF address in ePCO, and is expressed as, for example, Namf_Communication_N1N2MessageTransfer request (N1N2MessageTransferReqData(n1MessageContainer(PDU Session Establishment accept(Extended protocol configuration options(P-CSCF address=bb))), n2InfoContainer(smInfo(n2InfoContent(PDU Session Resource Setup Request Transfer))))).

[0059] S212: AMF 30A sends a response message (Namf_Communication_N1N2MessageTransfer response) to SMF 30B in response to the request message received in S211.

[0060] S213: The AMF 30A transmits a request message (PDU Session Resource Setup request) for setting up a PDU session resource to the base station 10A. The request message includes information indicating acceptance of the PDU session establishment request and the address of the P-CSCF 30G, 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)))))).

[0061] S214: The base station 10A transmits to the terminal 20A a message (RRCReconfiguration) related to RRC configuration, including information indicating acceptance of the PDU session establishment request. The message includes the address of the P-CSCF 30G 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)))))).

[0062] S215: The terminal 20A transmits to the base station 10A a message (RRCReconfigurationComplete) indicating that the RRC configuration has been completed.

[0063] S216: The base station 10A transmits to the AMF 30A a response message (PDU Session Resource Setup response) to the request message received in S213.

[0064] S217: AMF 30A sends a request message (Nsmf_PDUSession_UpdateSMContext request) requesting a PDU session context update to SMF 30B. For example, the request message is expressed as Nsmf_PDUSession_UpdateSMContext request (SmContextUpdateData(n2SmInfo(PDU Session Resource Setup Response Transfer))).

[0065] S218: SMF 30B sends a response message (Nsmf_PDUSession_UpdateSMContext response) to AMF 30A in response to the request message received in S217.

[0066] S219: SMF 30B sends a request message (PFCP Session Modification request) to UPF 30D1R to update the user data transfer path.

[0067] S220: UPF 30D1R sends a response message (PFCP Session Modification response) to the request message received in S219 to SMF 30B.

[0068] (IMS Voice Call) The procedure for an IMS voice call (start of voice communication) will be described. Fig. 5 is a diagram showing an example of a second sequence diagram according to an embodiment of the present invention. The processing of each step will be described below.

[0069] S301: The terminal 20A sends a message (SIP INVITE) requesting an IMS voice call to the P-CSCF 30G. The message includes, in the PANI, information indicating that the connection is via satellite (access type (access-type=3GPP-NR-SAT)), MCC, MNC, TAC, and NR cell identifier (NR cell ID), and includes, in the SDP offer, the IP address of the termination point of the calling terminal 20A. For example, the message is expressed as SIP INVITE (PANI(access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID), SDP offer(c=the originating UE IP address)).

[0070] S302: Based on the information about the access type (access-type=3GPP-NR-SAT) included in the message received in S301, P-CSCF30G decides to subscribe to PCF30C to obtain terminal connection information.

[0071] S303: P-CSCF30G sends a request message (Npcf_PolicyAuthorization_Create request) to PCF30C requesting subscription to satellite user plane route change events. The request message includes a request for immediate reporting. For example, the message is expressed as Npcf_PolicyAuthorization_Create request (AppSessionContext (ascReqData (evSubsc (events(event=SAT_UP_PATH_CH, notifMethod=EVENT_DETECTION), ImmeRep)))).

[0072] S304: Based on the information (SAT_UP_PATH_CH) included in the message received in S303, PCF30C decides to subscribe to the corresponding event (satellite user plane path change event) of the SMF.

[0073] S305: The PCF 30C transmits to the P-CSCF 30G a response message (Npcf_PolicyAuthorization_Create response) in response to the request message received in S303.

[0074] S306: PCF 30C sends a request message to SMF 30B to request a subscription to satellite user plane path change events, including a request for immediate reporting. For example, the message is expressed as Nsmf_EventExposure_Subscribe request (NsmfEventExposure (eventSubs (event=SAT_UP_PATH_CH), ImmeRep, notifMethod=ON_EVENT_DETECTION)).

[0075] S307: The SMF 30B sends a response message (Nsmf_EventExposure_Subscribe response) to the request message received in S306 to the PCF 30C.

[0076] S308: The SMF 30B sends to the PCF 30C a message (Nsmf_EventExposure_Notify request) related to an event notification, which includes the satellite type of the satellite that accommodates the terminal, the satellite constellation identifier, the satellite identifier, an indication of whether the PDU session of the terminal has a satellite ULCL and a satellite L-PSA (L-UPF), and an indication of whether the satellite L-PSA (L-UPF) has routing configuration between it and another satellite L-PSA (L-UPF) that corresponds to another terminal. For example, this message is expressed as Nsmf_EventExposure_Notify request (NsmfEventExposureNotification (eventNotifs (event=SAT_UP_PATH_CH, satellite type, satellite constellation id, satellite id, OnSatteliteLpsaUlcl=false, OnSatteliteMediaRoutingToTatgetNetwork=false))). OnSatteliteLpsaUlcl is information about whether an L-PSA and ULCL on a satellite are set up. OnSatteliteMediaRoutingToTatgetNetwork is information about whether an L-PSA has routing settings with other L-PSAs.

[0077] S309: The PCF 30C sends a response message (Nsmf_EventExposure_Notify response) to the message received in S306 to the SMF 30B.

[0078] S310: The PCF 30C sends to the P-CSCF 30G a message (Npcf_PolicyAuthorization_Notify request) including the satellite type of the satellite that accommodates the source terminal, the satellite constellation ID, the satellite ID, an indication of whether the PDU session of the source terminal has a satellite ULCL and a satellite L-PSA, and an indication of whether the satellite L-PSA has a routing setting between the satellite L-PSA and the destination network satellite L-PSA corresponding to the destination terminal. For example, the message is expressed as Npcf_PolicyAuthorization_Notify request (EventsNotification (evNotifs (event = SAT_UP_PATH_CH), satellite type, satellite constellation ID, satellite ID, OnSatteliteLpsaUlcl=false, OnSatteliteMediaRoutingToTatgetNetwork=false)).

[0079] S311: The P-CSCF30G recognizes that the media transfer device supports routing on the satellite constellation because it has information on the satellite ULCL and the satellite L-PSA, and further recognizes that its own device supports routing on the satellite constellation.

[0080] S312: The P-CSCF 30G transmits to the PCF 30C a response message (Npcf_PolicyAuthorization_Notify response) in response to the message received in S310.

[0081] S313: Since the P-CSCF 30G does not have information on the destination side, it assumes that the destination terminal is connected to a terrestrial network, and sets up a terrestrial IMS AGW.

[0082] S314: The P-CSCF 30G transmits to the IMS AGW 30FR a request message (H.248 ADD request) requesting settings related to (addition of) voice communication control.

[0083] S315: The IMS AGW 30FR acquires and sets resources of the termination point on its own device side related to data transmission with the destination side.

[0084] S316: The IMS AGW 30FR transmits to the P-CSCF 30G a response message (H.248 ADD response) in response to the request message received in S314.

[0085] S317: If the network has satellite media routing capability, the P-CSCF 30G sets a=satellite-optimal-routing-capable.

[0086] S318: The P-CSCF 30G sends to the S-CSCF 30H a negotiation offer (SDP offer) including an indication (a=satellite-optimal-routing-capable) indicating that routing over the satellite constellation is supported, and a message (SIP INVITE) requesting the initiation of voice communication including information on the satellite type, satellite constellation ID, and satellite ID. For example, the message is expressed as SIP INVITE (PANI (access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID), PSI (satellite-type=LEO CONSTELLATION, satellite constellation id, satellite-id), SDP offer (c= the originating ground IMS AGW IP address, a=satellite-optimal-routing-capable)).

[0087] In addition, in the area indicated as PSI above, a new private header field (IETF RFC 7315) "P-Satellite-Info Header Field" has been added (taking into account that PANI cannot be sent to other networks).

[0088] S319: The S-CSCF 30H transmits the message (SIP INVITE) received in S318 to the I-CSCF 30I.

[0089] The process following S319 will be described below. 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.

[0090] S321: I-CSCF 30I transmits to HSS 30J2 a request message (Nhss_ImsUECM_Authorize request) for discovery of an S-CSCF that accommodates the destination terminal.

[0091] S322: The HSS 30J2 transmits to the I-CSCF 30I a response message (Nhss_ImsUECM_Authorize response) in response to the request message received in S321.

[0092] S323: The I-CSCF 30I transmits the message (SIP INVITE) received in S318 of FIG. 5 to the S-CSCF 30H2.

[0093] S324: The S-CSCF 30H2 transmits the message (SIP INVITE) received in S323 to the P-CSCF 30G2.

[0094] S325: If the P-CSCF 30G2 has not received the satellite presence information of the destination terminal 20B (in reregistering), it assumes that the destination terminal 20B is connected to a terrestrial network, and sets up a terrestrial IMS AGW.

[0095] S326: The P-CSCF 30G2 transmits to the IMS AGW 30FR2 a request message (H.248 ADD request) requesting settings related to (addition of) voice communication control.

[0096] S327: The IMS AGW 30FR2 acquires and sets resources of its own termination point related to data transmission with the destination side.

[0097] S328: The IMS AGW 30FR2 transmits to the P-CSCF 30G2 a response message (H.248 ADD response) to the request message received in S326.

[0098] S329: P-CSCF30G2 deletes PANI and PSI from the message (SIP INVITE) received in S324, and generates a message in which the attribute a=satellite-optimal-routing-capable is deleted from the SDP offer.

[0099] S330: The P-CSCF 30G2 transmits the message (SIP INVITE) generated in S329 to the terminal 20B. For example, this message is expressed as SIP INVITE (SDP offer (c=the terminating ground IMS AGW IP address)).

[0100] S331: The terminal 20B transmits a message (183 Session Progress) indicating that voice communication is being set up to the P-CSCF 30G2. For example, this message is expressed as SIP 183 Session Progress (PANI(access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID), SDP answer (c= the terminating UE IP address)).

[0101] S332: Based on the access type (access-type=3GPP-NR-SAT) included in the message received in S331, P-CSCF30G2 determines to subscribe to PCF30C2 to obtain terminal connection information.

[0102] S333: P-CSCF30G2 sends a request message (Npcf_PolicyAuthorization_Create request) to PCF30C2 to request subscription to satellite user plane route change events. The request message includes a request for immediate reporting. For example, the message is expressed as Npcf_PolicyAuthorization_Create request (AppSessionContext (ascReqData (evSubsc (events(event=SAT_UP_PATH_CH, notifMethod=EVENT_DETECTION), ImmeRep)))).

[0103] S334: Based on the information (SAT_UP_PATH_CH) contained in the message received in S333, PCF30C decides to subscribe to the corresponding event (satellite user plane path change event) of the SMF.

[0104] S335: PCF 30C2 transmits to P-CSCF 30G2 a response message (Npcf_PolicyAuthorization_Create response) in response to the request message received in S333.

[0105] S336: The PCF 30C2 sends a request message to the SMF 30B2 to request a subscription to satellite user plane route change events, including a request for immediate reporting. For example, the message is expressed as Nsmf_EventExposure_Subscribe request (NsmfEventExposure (eventSubs (event=SAT_UP_PATH_CH), ImmeRep, notifMethod=ON_EVENT_DETECTION)).

[0106] S337: The SMF 30B2 sends a response message (Nsmf_EventExposure_Subscribe response) to the request message received in S336 to the PCF 30C2.

[0107] S338: The SMF 30B2 sends to the PCF 30C2 a message (Nsmf_EventExposure_Notify request) related to an event notification, which includes the satellite type of the satellite that accommodates the terminal, the satellite constellation identifier, the satellite identifier, an indication of whether the PDU session of the terminal has a satellite ULCL and a satellite L-PSA (L-UPF), and an indication of whether the satellite L-PSA (L-UPF) has routing configuration between it and another satellite L-PSA (L-UPF) that corresponds to another terminal. For example, this message is expressed as Nsmf_EventExposure_Notify request (NsmfEventExposureNotification (eventNotifs (event=SAT_UP_PATH_CH, satellite type, satellite constellation id, satellite id, OnSatteliteLpsaUlcl=false, OnSatteliteMediaRoutingToTatgetNetwork=false))). OnSatteliteLpsaUlcl is information about whether an L-PSA and ULCL on a satellite are set up. OnSatteliteMediaRoutingToTatgetNetwork is information about whether an L-PSA has routing settings with other L-PSAs.

[0108] S339: The PCF 30C2 sends a response message (Nsmf_EventExposure_Notify response) to the message received in S336 to the SMF 30B2.

[0109] S340: The PCF 30C2 sends to the P-CSCF 30G2 a message (Npcf_PolicyAuthorization_Notify request) including the satellite type of the satellite that accommodates the destination terminal, the satellite constellation ID, the satellite ID, an indication of whether the destination terminal's PDU session has a satellite ULCL and a satellite L-PSA, and an indication of whether the satellite L-PSA has routing configuration between the source network satellite L-PSA that corresponds to the source terminal. For example, this message is expressed as Npcf_PolicyAuthorization_Notify request (EventsNotification (evNotifs (event = SAT_UP_PATH_CH), satellite type, satellite constellation ID, satellite ID, OnSatteliteLpsaUlcl=false, OnSatteliteMediaRoutingToTatgetNetwork=false)).

[0110] S341: The P-CSCF30G2 recognizes that the media transfer device supports routing on the satellite constellation because there is information on the satellite ULCL and the satellite L-PSA, and further recognizes that the device itself supports routing on the satellite constellation.

[0111] S342: P-CSCF30G2 transmits to PCF30C2 a response message (Npcf_PolicyAuthorization_Notify response) in response to the message received in S340.

[0112] S343: P-CSCF30G2 recognizes that both the source network and its own network are capable of routing over a satellite constellation, and recognizes that routing over a satellite constellation is possible because the satellite constellation ID of the source network is the same as the satellite constellation ID of its own network. Note that if the source network and its own network are the same network and P-CSCF30G2 has not received PSI, it may compare the PANI of the source terminal with the PANI of the destination terminal and recognize that routing over a satellite constellation is possible from the setting information stored locally.

[0113] S344: The P-CSCF 30G2 sends a request message (Npcf_PolicyAuthorization_Create request) to the PCF 30C2 to request the setting of a policy for setting up an ULCL and a QoS flow for transmitting voice media. This is an instruction to start the setting for routing on the satellite constellation.

[0114] S345: The PCF 30C2 transmits to the P-CSCF 30G2 a response message (Npcf_PolicyAuthorization_Create response) in response to the request message received in S344.

[0115] S346: The PCF 30C2 sends a request message (Npcf_SMPolicyControl_UpdateNotify request) to the SMF 30B2 requesting an update of the policy related to the session.

[0116] S347: The SMF 30B2 sends to the PCF 30C2 a response message (Npcf_SMPolicyControl_UpdateNotify response) in response to the request message received in S346.

[0117] S348: The SMF 30B2 selects an ULCL and UPF (ULCL 30E2 and UPF 30D4L) on the satellite based on the satellite ID.

[0118] The process following S348 will be described below. Fig. 7 is a diagram showing an example of a fourth sequence diagram according to an embodiment of the present invention. The process of each step will be described below.

[0119] S351: SMF30B2 sends a request message (PFCP Session Establishment request) to UPF30D4L to establish a user data transfer path.

[0120] S352: UPF 30D4L sends a response message (PFCP Session Establishment response) to the request message received in S351 to SMF 30B2.

[0121] S353: SMF30B2 sends a request message (PFCP Session Establishment request) to ULCL30E2 to establish a user data transfer path.

[0122] S354: ULCL 30E2 transmits to SMF 30B2 a response message (PFCP Session Establishment response) to the request message received in S353.

[0123] S355: SMF30B2 sends a request message (PFCP Session Modification request) to UPF30D3R to update the user data transfer path.

[0124] S356: UPF 30D3R sends a response message (PFCP Session Modification response) to the request message received in S355 to SMF 30B2.

[0125] S357: SMF30B2 sends a request message (PFCP Session Modification request) to UPF30D4L to update the user data transfer path.

[0126] S358: UPF 30D4L sends a response message (PFCP Session Modification response) to the request message received in S357 to SMF 30B2.

[0127] S359: SMF 30B2 sends a request message (Namf_Communication_N1N2MessageTransfer request) to AMF 30A2 to update the PDU session resource settings. For example, this message is expressed as Namf_Communication_N1N2MessageTransfer request (N1N2MessageTransferReqData(n1MessageContainer(n1MessageContent(PDU Session Modification Command)), n2InfoContainer(smInfo(n2InfoContent(PDU Session Resource Modify Request Transfer))))).

[0128] S360: AMF 30A2 sends a response message (Namf_Communication_N1N2MessageTransfer response) to SMF 30B2 in response to the request message received in S359.

[0129] S361: The AMF 30A2 transmits a request message (PDU Session Resource Modify Request) for updating the setting of the PDU session resource to the base station 10B. For example, the message is expressed as PDU Session Resource Modify Request (NAS-PDU (DL NAS transport (Payload container type (N1 SM information), Payload container (PDU Session Modification Command))), PDU Session Resource Modify Request Transfer).

[0130] S362: The base station 10B transmits an RRC configuration message (RRCReconfiguration) including information indicating a PDU session update instruction to the terminal 20B. For example, the message is expressed as RRCReconfiguration(dedicatedNAS-Message(DL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Command)))).

[0131] S363: The terminal 20B transmits to the base station 10B a message (RRCReconfigurationComplete) indicating that the RRC configuration has been completed.

[0132] S364: The base station 10B transmits to the AMF 30A2 a response message (PDU Session Resource Modify response) to the request message received in S361.

[0133] S365: AMF 30A2 sends a request message (Nsmf_PDUSession_UpdateSMContext request) to SMF 30B2 requesting a context update of the PDU session. For example, the request message is expressed as Nsmf_PDUSession_UpdateSMContext request (SmContextUpdateData(n2SmInfo(PDU Session Resource Modify Response Transfer))).

[0134] S366: SMF30B2 sends a response message (Nsmf_PDUSession_UpdateSMContext response) to AMF30A2 in response to the request message received in S365.

[0135] S367: The terminal 20B transmits a message notifying the base station 10B of the completion of the PDU session modification to the base station 10B. For example, the message is expressed as ULInformationTransfer(dedicatedNAS-Message(UL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Complete)))).

[0136] S368: The base station 10B transmits a message to the AMF 30A2 notifying the completion of the PDU session update. For example, the message is expressed as Uplink NAS Transport(NAS-PDU(UL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Complete)))).

[0137] S369: AMF 30A2 sends a request message (Nsmf_PDUSession_UpdateSMContext request) to SMF 30B2 requesting a context update of the PDU session. For example, the request message is expressed as Nsmf_PDUSession_UpdateSMContext request (SmContextUpdateData(n2SmInfo(PDU Session Resource Modify Response Transfer))).

[0138] S370: SMF30B2 sends a response message (Nsmf_PDUSession_UpdateSMContext response) to AMF30A2 in response to the request message received in S369.

[0139] The process following S370 will be described. Fig. 8 is a diagram showing an example of a fifth sequence diagram according to an embodiment of the present invention. The process of each step will be described below.

[0140] In the following steps S371 to S373, the release of the terrestrial IMS AGW is executed in parallel with the setting process of the ULCL30E2 described above.

[0141] S371: The P-CSCF 30G2 transmits to the IMS AGW 30FR2 a request message (H.248 SUBTRACT request) requesting settings related to the deletion of control of voice communication.

[0142] S372: The IMS AGW 30FR2 deletes the setting executed in S327 of FIG.

[0143] S373: The IMS AGW 30FR2 transmits to the P-CSCF 30G2 a response message (H.248 SUBTRACT response) in response to the request message received in S371.

[0144] S374: In parallel with the procedure in the destination network, the P-CSCF30G2 executes the following message transmission process to the source network.

[0145] S375: If the P-CSCF30G2's own network has satellite media routing capability, it sets a=satellite-optimal-routing-capable.

[0146] S376: P-CSCF30G2 sends to S-CSCF30H2 a negotiation answer (SDP answer) including an indication (a=satellite-optimal-routing-capable) indicating that routing over the satellite constellation is supported, and a message (183 Session Progress) indicating that voice communication is being set up, including information on the satellite type, satellite constellation ID, and satellite ID. For example, this message is expressed as SIP 183 Session Progress (PANI(access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID), PSI(satellite-type=LEO CONSTELLATION, satellite constellation id, satellite-id), SDP answer (c= the terminating side dummy IP address, a=satellite-optimal-routing-capable)).

[0147] S377: The S-CSCF 30H2 transmits the message (183 Session Progress) received in S376 to the I-CSCF 30I.

[0148] S378: I-CSCF 30I transmits the message (183 Session Progress) received in S377 to S-CSCF 30H.

[0149] S379: The S-CSCF 30H transmits the message (183 Session Progress) received in S378 to the P-CSCF 30G.

[0150] S380: P-CSCF30G recognizes that both its own network and the destination network are capable of routing over a satellite constellation, and recognizes that routing over a satellite constellation is possible because the satellite constellation ID of its own network is the same as the satellite constellation ID of the destination network. Note that if the own network and the destination network are the same network and PSI has not been received, P-CSCF30G may compare the PANI of the source terminal with the PANI of the destination terminal and recognize that routing over a satellite constellation is possible from the setting information stored locally.

[0151] S381: The P-CSCF 30G sends a request message (Npcf_PolicyAuthorization_Create request) to the PCF 30C to request the setting of a policy for setting up an ULCL and a QoS flow for transmitting voice media. This is an instruction to start the setting for routing on the satellite constellation.

[0152] S382: The PCF 30C transmits to the P-CSCF 30G a response message (Npcf_PolicyAuthorization_Create response) in response to the request message received in S381.

[0153] S383: The PCF 30C sends a request message (Npcf_SMPolicyControl_UpdateNotify request) to the SMF 30B requesting an update of the policy related to the session.

[0154] S384: The SMF 30B sends to the PCF 30C a response message (Npcf_SMPolicyControl_UpdateNotify response) in response to the request message received in S383.

[0155] S385: SMF30B selects the ULCL and local PDU session termination point (L-PSA) on the satellite based on the satellite ID.

[0156] The process following S385 will be described. Fig. 9 is a diagram showing an example of a sixth sequence diagram according to an embodiment of the present invention. The process of each step will be described below.

[0157] S391: SMF30B sends a request message (PFCP Session Establishment request) to UPF30D2L to establish a user data transfer path.

[0158] S392: UPF30D2L sends a response message (PFCP Session Establishment response) to the request message received in S391 to SMF30B.

[0159] S393: SMF30B sends a request message (PFCP Session Establishment request) to ULCL30E to establish a user data transfer path.

[0160] S394: ULCL 30E transmits to SMF 30B a response message (PFCP Session Establishment response) to the request message received in S393.

[0161] S395: SMF30B sends a request message (PFCP Session Modification request) to UPF30D1R to update the user data transfer path.

[0162] S396: UPF 30D1R sends a response message (PFCP Session Modification response) to the request message received in S395 to SMF 30B.

[0163] S397: SMF30B sends a request message (PFCP Session Modification request) to UPF30D2L to update the user data transfer path.

[0164] S398: UPF30D2L sends a response message (PFCP Session Modification response) to the request message received in S397 to SMF30B.

[0165] S399: SMF 30B sends a request message (Namf_Communication_N1N2MessageTransfer request) for updating the setting of PDU session resources to AMF 30A. For example, this message is expressed as Namf_Communication_N1N2MessageTransfer request (N1N2MessageTransferReqData(n1MessageContainer(n1MessageContent(PDU Session Modification Command)), n2InfoContainer(smInfo(n2InfoContent(PDU Session Resource Modify Request Transfer))))).

[0166] S400: AMF 30A sends a response message (Namf_Communication_N1N2MessageTransfer response) to SMF 30B in response to the request message received in S399.

[0167] S401: The AMF 30A transmits a request message (PDU Session Resource Modify Request) for updating the setting of a PDU session resource to the base station 10A. For example, the message is expressed as PDU Session Resource Modify Request (NAS-PDU (DL NAS transport (Payload container type (N1 SM information), Payload container (PDU Session Modification Command))), PDU Session Resource Modify Request Transfer).

[0168] S402: The base station 10A transmits an RRC configuration message (RRCReconfiguration) including information indicating a PDU session update instruction to the terminal 20A. For example, the message is expressed as RRCReconfiguration(dedicatedNAS-Message(DL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Command)))).

[0169] S403: The terminal 20A transmits to the base station 10A a message (RRCReconfigurationComplete) indicating that the RRC configuration has been completed.

[0170] S404: The base station 10A sends a response message (PDU Session Resource Modify response) to the request message received in S401 to the AMF 30A.

[0171] S405: AMF 30A sends a request message (Nsmf_PDUSession_UpdateSMContext request) requesting a context update of the PDU session to SMF 30B. For example, the request message is expressed as Nsmf_PDUSession_UpdateSMContext request (SmContextUpdateData(n2SmInfo(PDU Session Resource Modify Response Transfer))).

[0172] S406: SMF 30B sends a response message (Nsmf_PDUSession_UpdateSMContext response) to AMF 30A in response to the request message received in S405.

[0173] S407: The terminal 20A transmits a message notifying the base station 10A of the completion of the PDU session modification. For example, the message is expressed as ULInformationTransfer(dedicatedNAS-Message(UL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Complete)))).

[0174] S408: The base station 10A transmits a message to the AMF 30A notifying the completion of the PDU session modification. For example, the message is expressed as Uplink NAS Transport(NAS-PDU(UL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Complete)))).

[0175] S409: AMF 30A sends a request message (Nsmf_PDUSession_UpdateSMContext request) requesting a context update of the PDU session to SMF 30B. For example, the request message is expressed as Nsmf_PDUSession_UpdateSMContext request (SmContextUpdateData(n2SmInfo(PDU Session Resource Modify Response Transfer))).

[0176] S410: SMF 30B sends a response message (Nsmf_PDUSession_UpdateSMContext response) to AMF 30A in response to the request message received in S409.

[0177] The process following S410 will now be described. Fig. 10 is a diagram showing an example of a seventh sequence diagram according to an embodiment of the present invention. The process of each step will now be described.

[0178] In the following steps S411 to S413, the release of the terrestrial IMS AGW is executed in parallel with the setting process of the ULCL30E described above.

[0179] S411: The P-CSCF 30G transmits to the IMS AGW 30FR a request message (H.248 SUBTRACT request) requesting settings related to the deletion of control of voice communication.

[0180] S412: The IMS AGW 30FR deletes the setting executed in S315 of FIG.

[0181] S413: The IMS AGW 30FR transmits to the P-CSCF 30G a response message (H.248 SUBTRACT response) in response to the request message received in S411.

[0182] S414: In parallel with the procedure in the source network, the P-CSCF 30G executes the following message transmission process to the destination network.

[0183] S415: The P-CSCF 30G deletes PANI and PSI from the message (SIP 183 Session Progress) received in S379 of FIG. 8, and generates a message by deleting the attribute a=satellite-optimal-routing-capable from the SDP answer.

[0184] S416: The P-CSCF 30G transmits the message (SIP 183 Session Progress) generated in S415 to the terminal 20B. For example, this message is expressed as SIP 183 Session Progress (SDP answer (c= the originating side dummy IP address)).

[0185] S417: The terminal 20A sends a PRACK (Provisional response acknowledgement) to the P-CSCF 30G as a response to the SIP 183 Session Progress received in S416. For example, this message is expressed as PRACK (PANI (access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID), SDP offer (c= the originating UE IP address)).

[0186] S418: The P-CSCF 30G recognizes that the IMS AGW has not been configured, and decides to configure the IMS AGW 30FL.

[0187] S419: The P-CSCF 30G transmits to the IMS AGW 30FL a request message (H.248 ADD request) requesting settings related to (addition of) voice communication control.

[0188] S420: The IMS AGW 30FL acquires and sets resources of its own device-side termination point related to data transmission with the destination side.

[0189] S421: The IMS AGW 30FL transmits to the P-CSCF 30G a response message (H.248 ADD response) in response to the request message received in S419.

[0190] S422: P-CSCF 30G transmits the message (PRACK) received in S417 to S-CSCF 30H. For example, the message is expressed as PRACK (PANI (access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID), PSI (satellite-type=LEO CONSTELLATION, satellite constellation id, satellite-id), SDP offer (c= the originating satellite IMS AGW IP address, a=satellite-optimal-routing-capable)).

[0191] S423: The S-CSCF 30H transmits the message (PRACK) received in S422 to the I-CSCF 30I.

[0192] S424: The I-CSCF 30I transmits the message (PRACK) received in S423 to the S-CSCF 30H2.

[0193] S425: The S-CSCF 30H2 transmits the message (PRACK) received in S424 to the P-CSCF 30G2.

[0194] The process following S425 will be described. Fig. 11 is a diagram showing an example of an eighth sequence diagram according to an embodiment of the present invention. The process of each step will be described below.

[0195] S431: The P-CSCF 30G2 recognizes that the IMS AGW has not been configured, and decides to configure the IMS AGW 30FL2.

[0196] S432: The P-CSCF 30G2 transmits to the IMS AGW 30FL2 a request message (H.248 ADD request) requesting settings related to (addition of) voice communication control.

[0197] S433: The IMS AGW 30FL2 acquires and sets resources of its own termination point related to data transmission with the destination side.

[0198] S434: The IMS AGW 30FL2 transmits to the P-CSCF 30G2 a response message (H.248 ADD response) in response to the request message received in S432.

[0199] S435: P-CSCF30G2 deletes PANI and PSI from the message (PRACK) received in S425 of FIG. 10, and generates a message in which the attribute a=satellite-optimal-routing-capable is deleted from the SDP offer.

[0200] S436: The P-CSCF 30G2 transmits the message (PRACK) generated in S435 to the terminal 20B. For example, this message is expressed as PRACK (SDP offer (c=the terminating satellite IMS AGW IP address)).

[0201] S437: The terminal 20B transmits to the P-CSCF 30G2 a response message (200 OK (PRACK)) in response to the message received in S436. For example, the response message is expressed as 200 OK (PRACK) (SDP answer (c = the terminating UE IP address)).

[0202] S438: The P-CSCF 30G2 transmits to the IMS AGW 30FL2 a request message (H.248 MOD request) requesting settings related to (modification of) control of voice communication.

[0203] S439: The IMS AGW 30FL2 sets a termination point on the destination side for data transmission with the destination side.

[0204] S440: The IMS AGW 30FL2 transmits to the P-CSCF 30G2 a response message (H.248 MOD response) in response to the request message received in S438.

[0205] S441: The P-CSCF 30G2 transmits to the IMS AGW 30FL2 a request message (H.248 ADD request) requesting settings related to (addition of) voice communication control.

[0206] S442: The IMS AGW 30FL2 sets a source termination point for data transmission to the source network, and requests acquisition of resources for the termination point on its own device side.

[0207] S443: The IMS AGW 30FL2 transmits to the P-CSCF 30G2 a response message (H.248 ADD response) in response to the request message received in S441.

[0208] S444: The P-CSCF 30G2 transmits the message (200 OK (PRACK)) received in S437 to the S-CSCF 30H2.

[0209] S445: The S-CSCF 30H2 transmits the message (200 OK (PRACK)) received in S444 to the I-CSCF 30I.

[0210] S446: I-CSCF 30I transmits the message (200 OK (PRACK)) received in S445 to S-CSCF 30H.

[0211] S447: The S-CSCF 30H transmits the message (200 OK (PRACK)) received in S446 to the P-CSCF 30G.

[0212] S448: The P-CSCF 30G transmits to the IMS AGW 30FL a request message (H.248 MOD request) requesting settings related to (modification of) control of voice communication.

[0213] S449: The IMS AGW 30FL sets a termination point on the destination side for data transmission with the destination side.

[0214] S450: The IMS AGW 30FL transmits to the P-CSCF 30G a response message (H.248 MOD response) in response to the request message received in S448.

[0215] S451: The P-CSCF 30G transmits to the IMS AGW 30FL a request message (H.248 ADD request) requesting settings related to (addition of) voice communication control.

[0216] S452: The IMS AGW 30FL sets a terminal-side termination point for terminal-directed data transmission, and requests acquisition of resources for the termination point on the IMS AGW 30FL's own device side.

[0217] S453: The IMS AGW 30FL transmits to the P-CSCF 30G a response message (H.248 ADD response) in response to the request message received in S451.

[0218] The process following S453 will be described. Fig. 12 is a diagram showing an example of a ninth sequence diagram according to an embodiment of the present invention. The process of each step will be described below.

[0219] S461: The P-CSCF 30G transmits the message (200 OK (PRACK)) received in S447 of FIG. 11 to the terminal 20A.

[0220] S462: The terminal 20A sends an UPDATE, which is a method for updating a session in SIP, to the P-CSCF 30G.

[0221] S463: The P-CSCF 30G transmits the message (UPDATE) received in S462 to the S-CSCF 30H.

[0222] S464: The S-CSCF 30H transmits the message (UPDATE) received in S463 to the I-CSCF 30I.

[0223] S465: The I-CSCF 30I transmits the message (UPDATE) received in S464 to the S-CSCF 30H2.

[0224] S466: The S-CSCF 30H2 transmits the message (UPDATE) received in S465 to the P-CSCF 30G2.

[0225] S467: The P-CSCF 30G2 transmits the message (UPDATE) received in S466 to the terminal 20B.

[0226] S468: The terminal 20B transmits to the P-CSCF 30G2 a response message (200 OK (UPDATE)) in response to the message received in S467.

[0227] S469: The P-CSCF 30G2 transmits the message (200 OK (UPDATE)) received in S468 to the S-CSCF 30H2.

[0228] S470: S-CSCF 30G2 transmits the message (200 OK (UPDATE)) received in S469 to I-CSCF 30I.

[0229] S471: The I-CSCF 30I transmits the message (200 OK (UPDATE)) received in S470 to the S-CSCF 30H.

[0230] S472: The S-CSCF 30H transmits the message (200 OK (UPDATE)) received in S471 to the P-CSCF 30G.

[0231] S473: The P-CSCF 30G transmits the message (200 OK (UPDATE)) received in S472 to the terminal 20A.

[0232] S474: The terminal 20B transmits a success response (SIP 200 OK) to the P-CSCF 30G2.

[0233] S475: The P-CSCF 30G2 transmits the success response (SIP 200 OK) received in S474 to the S-CSCF 30H2.

[0234] S476: S-CSCF30G2 transmits the success response (SIP 200 OK) received in S475 to I-CSCF30I.

[0235] S477: The I-CSCF 30I transmits the success response (SIP 200 OK) received in S476 to the S-CSCF 30H.

[0236] S478: The S-CSCF 30H transmits the success response (SIP 200 OK) received in S477 to the P-CSCF 30G.

[0237] S479: The P-CSCF 30G transmits the success response (SIP 200 OK) received in S478 to the terminal 20A.

[0238] S480: The terminal 20A transmits an acknowledgement (ACK) to the P-CSCF 30G in response to the message received in S479.

[0239] S481: The P-CSCF 30G transmits the acknowledgement (ACK) received in S480 to the S-CSCF 30H.

[0240] S482: The S-CSCF 30H transmits the acknowledgement (ACK) received in S481 to the I-CSCF 30I.

[0241] S483: The I-CSCF 30I transmits the acknowledgement (ACK) received in S482 to the S-CSCF 30H2.

[0242] S484: The S-CSCF 30H2 transmits the acknowledgement (ACK) received in S483 to the P-CSCF 30G2.

[0243] S485: The P-CSCF 30G2 transmits the acknowledgement (ACK) received in S484 to the terminal 20B.

[0244] S486: Voice communication is established between the originating terminal 20A and the terminating terminal 20B via two IMS AGWs (IMS AGW 30FL and IMS AGW 30FL2) on the satellite.

[0245] (Satellite Transfer) The following describes a satellite transfer procedure in which the satellite accommodating the calling terminal 20A is switched to another satellite after an IMS voice call (start of voice communication) is completed. Fig. 13 is a diagram showing an example of a tenth sequence diagram in the embodiment of the present invention. The sequence diagram in Fig. 13 shows an Xn handover procedure. The processing of each step will be described below.

[0246] S501: The base station 10A transmits a handover request to the base station 10C.

[0247] S502: The base station 10C transmits a handover request acknowledgement including a handover command to the base station 10A as a response to the handover request received in S501.

[0248] S503: The base station 10A transmits a message (RRCReconfiguration) requesting execution of settings related to radio resource control (RRC) to the terminal 20A. The message includes a handover command.

[0249] S504: The base station 10A sends an SN status transfer to the base station 10C.

[0250] S505: The terminal 20A transmits a message to the base station 10C notifying that the RRC-related settings have been completed. The message includes a handover confirmation.

[0251] S506: The base station 10C transmits to the AMF 30A a request message (Path Switch request) requesting a path change accompanying a change of base station.

[0252] S507: AMF 30A recognizes the satellite constellation ID and satellite ID currently accommodating terminal 20A based on the correspondence between the transport layer settings and the identifier of the source base station that it recognized in advance, and the transport layer settings of the request message received in S506.

[0253] S508: AMF 30A sends a request message (Nsmf_PDUSession_UpdateSMContext request) requesting path switching accompanying a change in base station to SMF 30B. The request message includes a satellite constellation ID and a satellite ID, and is expressed as, for example, Nsmf_PDUSession_UpdateSMContext request (SmContextUpdateData (satellite constellation id, satellite id)).

[0254] S509: Based on the fact that the satellite ID stored for terminal 20A is different from the satellite ID received in S508, SMF 30B recognizes that the satellite on which base station 10A of the source station is located is different from the satellite on which base station 10C of the destination station is located.

[0255] S510: SMF 30B sends a request message (PFCP Session Modification request) for updating the user data transfer path to ULCL 30E.

[0256] S511: ULCL 30E transmits to SMF 30B a response message (PFCP Session Modification response) to the request message received in S510.

[0257] S512: SMF 30B sends a response message (Nsmf_PDUSession_UpdateSMContext response) to AMF 30A in response to the request message received in S508.

[0258] S513: The AMF 30A transmits to the base station 10C a response message (Path Switch request response) in response to the request message received in S506.

[0259] S514: The base station 10C transmits a message (UE Context Release) requesting the release of the terminal context to the base station 10A.

[0260] Next, we will explain the procedures related to changing the ULCL and the termination point (PSA) in the PDU session when switching satellites. Figure 14 is a diagram showing an example of an eleventh sequence diagram in an embodiment of the present invention. Below, we will explain the processing of each step.

[0261] S521: SMF 30B recognizes the base station switch and the satellite ID switch, and decides to execute the switch for the ULCL and the local UPF (L-UPF) deployed on the satellite. Here, the L-UPF may be expressed as the PDU session termination point (L-PSA).

[0262] S522: Using the event subscription set when the voice call was made, SMF30B decides to inquire of the P-CSCF via the PCF whether to allow switching from the pre-movement ULCL and pre-movement L-UPF to the destination ULCL and destination L-UPF (L-PSA).

[0263] S523: SMF 30B transmits to PCF 30C a message (Nsmf_EventExposure_Notify request) that inquires about whether to switch the ULCL and L-UPF and notifies the PCF 30C of an event including an indication (EARLY) that the ULCL and L-UPF (L-PSA) have not yet been moved. For example, this message is expressed as Nsmf_EventExposure_Notify request (NsmfEventExposureNotification (eventNotifs (event=SAT_UP_PATH_CH, dnaiChgType=EARLY, satellite type, satellite constellation id, satellite id= a target satellite id, OnSatteliteLpsaUlcl=true, OnSatteliteMediaRoutingToTatgetNetwork=false))).

[0264] S524: The PCF 30C sends a response message (Nsmf_EventExposure_Notify response) to the message received in S523 to the SMF 30B.

[0265] S525: PCF 30C transmits to P-CSCF 30G a message (Npcf_PolicyAuthorization_Notify request) that inquires about whether to switch the ULCL and L-UPF and notifies the P-CSCF 30G of an event including an indication (EARLY) that the ULCL and L-PSA have not yet been moved. For example, this message is expressed as Npcf_PolicyAuthorization_Notify request (EventsNotification (evNotifs (event=SAT_UP_PATH_CH), dnaiChgType=EARLY, satellite type, satellite constellation id, satellite id= a target satellite id, OnSatteliteLpsaUlcl=true, OnSatteliteMediaRoutingToTatgetNetwork=false)).

[0266] S526: The P-CSCF 30G transmits to the PCF 30C a response message (Npcf_PolicyAuthorization_Notify response) in response to the message received in S525.

[0267] S527: If the satellite constellation IDs of the originating and terminating terminals are the same even after switching between ULCL and L-UPF, P-CSCF30G determines that media routing on the satellite is possible. Also, P-CSCF30G recognizes that it is necessary to start setting up the destination IMS AGW.

[0268] S528: P-CSCF30G transmits to PCF30G a message (Npcf_EventExposure_AppRelocationInfo request) indicating approval of the switching between ULCL and L-UPF.

[0269] S529: The PCF 30G transmits to the P-CSCF 30G a response message (Npcf_EventExposure_AppRelocationInfo response) in response to the message received in S528.

[0270] S530: PCF 30G sends a message (Nsmf_EventExposure_AppRelocationInfo request) to SMF 30B indicating approval of the switching between ULCL and L-UPF.

[0271] S531: The SMF 30B sends a response message (Nsmf_EventExposure_AppRelocationInfo response) to the message received in S530 to the PCF 30C.

[0272] S532: The SMF 30B determines to execute the setting of the destination ULCL (ULCL 30E) and the destination L-UPF (UPF 30D5L3).

[0273] S533: The SMF 30B selects the destination ULCL (ULCL 30E) and the destination L-UPF (UPF 30D5L3) based on the satellite ID to which the destination base station 10C belongs.

[0274] The process following S533 will be described. Fig. 15 is a diagram showing an example of a twelfth sequence diagram according to an embodiment of the present invention. The process of each step will be described below.

[0275] S541: SMF30B sends a request message (PFCP Session Establishment request) to UPF30D5L3 requesting the establishment of a path for transferring user data for uplink (UL).

[0276] S542: UPF 30D5L3 sends a response message (PFCP Session Establishment response) to the request message received in S541 to SMF 30B. The response message includes a packet detection rule (PDR) in which information indicating the UL data termination point (TEID for UL in PSA5) is set. For example, the response message is expressed as PFCP Session Establishment response (PDR = TEID (Tunnel Endpoint IDentifier) ​​for UL in PSA5).

[0277] S543: The SMF 30B transmits a request message (PFCP Session Establishment request) to the ULCL 30E3 requesting establishment of a path for transferring user data. The request message includes information for setting a dummy value as a UL traffic filter for the destination L-UPF (UPF 30D5L3) and information for setting the termination point of the source IMS AGW (IMS AGW 30FL) as a UL traffic filter for the source ULCL (ULCL 30E). For example, the request message includes a first request message for UL for PSA5, a second request message for UL for PSA1, a third request message for UL originating from the base station 10B, a fourth request message for DL, a fifth request message for tunnel UL, and a sixth request message for tunnel DL. Furthermore, the first request message is expressed as a PFCP Session Establishment request (Traffic filter for UL to PSA5=dummy value, FAR=PSA5 UL TEID), the second request message is expressed as a PFCP Session Establishment request (Traffic filter for UL to PSA1=default, FAR=PSA1 UL TEID), the fourth request message is expressed as a PFCP Session Establishment request (FAR=target gNB DL TEID), the fifth request message is expressed as a PFCP Session Establishment request (Traffic filter for UL to source ULCL=source satellite IMS AGW IP address, FAR=source ULCL UL TEID), and the sixth request message is expressed as a PFCP Session Establishment request (PDR request), where FAR indicates a Forwarding Action Rule.

[0278] S544: ULCL 30E3 transmits a response message (PFCP Session Establishment response) to the request message received in S543 to SMF 30B. Note that the response message to the third request message is expressed as PFCP Session Establishment response (PDR=target ULCL UL TEID), the response message to the fourth request message is expressed as PFCP Session Establishment response (PDR=target ULCL DL TEID), and the response message to the sixth request message is expressed as PFCP Session Establishment response (PDR=target ULCL DL forwarding TEID).

[0279] S545: SMF 30B sends a request message (PFCP Session Modification request) for updating the user data forwarding path for the tunnel DL to ULCL 30E. For example, this request message is expressed as PFCP Session Modification request (FAR = target ULCL DL forwarding TEID).

[0280] S546: ULCL 30E sends a response message (PFCP Session Modification response) to the request message received in S545 to SMF 30B.

[0281] S547: The SMF 30B sends a request message (PFCP Session Modification request) for updating the DL user data transfer path to the UPF 30D1R. For example, the request message is expressed as a PFCP Session Modification request (FAR=target ULCL DL TEID).

[0282] S548: UPF30D1R sends a response message (PFCP Session Modification response) to the request message received in S547 to SMF30B.

[0283] S549: The SMF 30B sends a request message (PFCP Session Modification request) to the UPF 30D 5L3 to update the DL user data transfer path. For example, the request message is expressed as PFCP Session Modification request (FAR = target ULCL DL TEID).

[0284] S550: UPF 30D5L3 sends a response message (PFCP Session Modification response) to the request message received in S549 to SMF 30B.

[0285] S551: SMF 30B sends a request message (Namf_Communication_N1N2MessageTransfer request) for updating the setting of PDU session resources to AMF 30A. For example, the request message is expressed as Namf_Communication_N1N2MessageTransfer request (N1N2MessageTransferReqData(n2InfoContainer(smInfo(n2InfoContent(PDU Session Resource Modify Request Transfer(UL NG-U UP TNL Information=target ULCL UL TEID)))))).

[0286] S552: AMF 30A sends a response message (Namf_Communication_N1N2MessageTransfer response) to SMF 30B in response to the request message received in S551.

[0287] S553: ​​The AMF 30A transmits a request message (PDU Session Resource Modify Request) for updating the PDU session resource settings to the base station 10C. For example, the message is expressed as PDU Session Resource Modify Request (PDU Session Resource Modify Request Transfer (UL NG-U UP TNL Information = target ULCL UL TEID)).

[0288] S554: In the base station 10C, the AMF 30A sends a response message (PDU Session Resource Modify response) to the request message received in S553.

[0289] S555: AMF 30A sends a request message (Nsmf_PDUSession_UpdateSMContext request) requesting a context update of the PDU session to SMF 30B. For example, the request message is expressed as Nsmf_PDUSession_UpdateSMContext request (SmContextUpdateData(n2SmInfo(PDU Session Resource Modify Response Transfer))).

[0290] S556: SMF 30B sends a response message (Nsmf_PDUSession_UpdateSMContext response) to AMF 30A in response to the request message received in S555.

[0291] The current flow of UL and DL signaling and UL and DL media data will be described. Figure 16 is a diagram showing an example of a thirteenth sequence diagram in an embodiment of the present invention. The processing of each step will be described below.

[0292] As shown in S561, UL signaling (control signal) is transmitted from the terminal 20A to the called side via the base station 10C, ULCL 30E3, UPF 30D1R, and P-CSCF 30G.

[0293] As shown in S562, DL signaling (control signal) from the receiving side is transmitted to the terminal 20A via the P-CSCF 30G, the UPF 30D1R, the ULCL 30E3, and the base station 10C.

[0294] As shown in S563, the UL media (voice signal) is transmitted via the source IMS AGW 30FL. That is, the UL media is transmitted from the terminal 20A to the IMS AGW 30FL2 on the receiving side via the base station 10C, ULCL 30E3, ULCL 30E, UPF 30D2L, and IMS AGW 30FL.

[0295] As shown in S564, the DL media (voice signal) is received via the source IMS AGW 30FL. That is, the DL media is received by the terminal 20A from the destination IMS AGW 30FL2 via the IMS AGW 30FL, the UPF 30D2L, the ULCL 30E, the ULCL 30E3, and the base station 10C.

[0296] As shown in S565, a dummy value is set in the UL traffic filter of ULCL 30E3 for UPF 30D5L3, so that UL media (audio signal) is not transmitted to UPF 30D5L3.

[0297] The following describes the processing following S556 in Fig. 15. Fig. 17 is a diagram showing an example of a fourteenth sequence diagram according to an embodiment of the present invention. The processing of each step will be described below.

[0298] S571: SMF30B uses the event subscription set when the voice call was made to decide to notify the P-CSCF via the PCF that the destination ULCL and destination L-UPF have been set.

[0299] S572: SMF 30B sends to PCF 30C a message (Nsmf_EventExposure_Notify) notifying the completion of switching between the ULCL and L-UPF, and notifying an event including an indication (LATE) indicating that the transition to the ULCL and L-UPF of the satellite after the transition has occurred. For example, this request message is expressed as Nsmf_EventExposure_Notify request (NsmfEventExposureNotification (eventNotifs (event=SAT_UP_PATH_CH, dnaiChgType=LATE, satellite type, satellite constellation id, satellite id= a target satellite id, OnSatteliteLpsaUlcl=true, OnSatteliteMediaRoutingToTatgetNetwork=false))).

[0300] S573: The PCF 30C sends a response message (Nsmf_EventExposure_Notify response) to the message received in S572 to the SMF 30B.

[0301] S574: PCF30C transmits to P-CSCF30G a message (Npcf_PolicyAuthorization_Notify request) notifying the completion of switching between the ULCL and L-UPF, and notifying the P-CSCF30G of an event including an indication (LATE) indicating that the transition to the ULCL and L-UPF of the satellite after the transition has occurred. For example, the request message is expressed as Npcf_PolicyAuthorization_Notify request (EventsNotification (evNotifs (event=SAT_UP_PATH_CH), dnaiChgType=LATE, satellite type, satellite constellation id, satellite id= a target satellite id, OnSatteliteLpsaUlcl=true, OnSatteliteMediaRoutingToTatgetNetwork=false)).

[0302] S575: The P-CSCF 30G transmits to the PCF 30C a response message (Npcf_PolicyAuthorization_Notify response) in response to the message received in S574.

[0303] S576: The P-CSCF 30G recognizes that the destination IMS AGW 30FL3 needs to be configured.

[0304] S577: P-CSCF30G transmits to PCF30G a message (Npcf_EventExposure_AppRelocationInfo request) indicating that the switching between ULCL and L-UPF is approved.

[0305] S578: The PCF 30G transmits to the P-CSCF 30G a response message (Npcf_EventExposure_AppRelocationInfo response) in response to the message received in S577.

[0306] S579: PCF 30G sends a message (Nsmf_EventExposure_AppRelocationInfo request) to SMF 30B indicating that the switching between ULCL and L-UPF is approved.

[0307] S580: The SMF 30B sends a response message (Nsmf_EventExposure_AppRelocationInfo response) to the message received in S579 to the PCF 30C.

[0308] S581: SMF 30B determines to transmit an instruction to enable terminal 20A to recognize the PANI change, i.e., to have terminal 20A confirm the NR cell ID after movement.

[0309] S582: SMF 30B sends a request message (Namf_Communication_N1N2MessageTransfer request) related to the PANI change in terminal 20A to AMF 30A. For example, the request message is expressed as Namf_Communication_N1N2MessageTransfer request (N1N2MessageTransferReqData (n2InfoContainer (smInfo (n2InfoContent (Location Reporting Control (Location Reporting Request Type (Event Type = one time change of IMS PANI in UE))))))).

[0310] S583: AMF 30A sends a response message (Namf_Communication_N1N2MessageTransfer response) to SMF 30B in response to the request message received in S582.

[0311] S584: The AMF 30A transmits a message (Location Reporting Control) to the base station 10C requesting the terminal 20A to confirm the NR cell ID. For example, the message is expressed as Location Reporting Control (Location Reporting Request Type (Event Type = one time change of IMS PANI in UE)).

[0312] S585: The base station 10C sends a response message (Location Report) to the AMF 30A in response to the request message received in S584.

[0313] S586: AMF 30A sends a request message (Nsmf_PDUSession_UpdateSMContext request) requesting a PDU session context update to SMF 30B. For example, the request message is expressed as Nsmf_PDUSession_UpdateSMContext request (SmContextUpdateData (n2SmInfo (Location Report))).

[0314] S587: SMF 30B sends a response message (Nsmf_PDUSession_UpdateSMContext response) to AMF 30A in response to the request message received in S586.

[0315] S588: The base station 10C transmits to the terminal 20A a message (RRCReconfiguration) related to RRC configuration, which includes information requesting the terminal 20A to acquire system information (SIB) of the serving cell and transmit a measurement report.

[0316] S589: The terminal 20A transmits to the base station 10C a response message (RRCReconfigurationComplete) in response to the message received in S588.

[0317] S590: Terminal 20A recognizes that the NR cell ID of the current accommodating cell is different from the NR cell ID set in the message requesting the start of voice communication at S323 in Figure 6, recognizes that the contents of PANI will change, and therefore recognizes that a re-INVITE needs to be sent.

[0318] S591: The terminal 20A sends a message (SIP re-INVITE) to the P-CSCF 30G requesting an update of the voice communication status, including the NR cell ID of the current accommodating cell.

[0319] S592: The P-CSCF 30G transmits to the IMS AGW 30FL3 a request message (H.248 ADD request) requesting settings related to (addition of) voice communication control.

[0320] S593: The IMS AGW 30FL3 acquires and sets resources of its own termination point related to data transmission with the destination side.

[0321] S594: The IMS AGW 30FL3 sends a response message (H.248 ADD response) to the request message received in S592 to the P-CSCF 30G. The response message includes information about the termination point in the destination IMS AGW 30FL3, regarding data transmission with the terminating side.

[0322] The process following S594 will be described. Fig. 18 is a diagram showing an example of a fifteenth sequence diagram according to an embodiment of the present invention. The process of each step will be described below.

[0323] S601: The P-CSCF30G normally sets the "IP address of the termination point in the IMS AGW30FL3 on the destination satellite of the source network" in the c= line in the SDP of the SIP message, but taking into consideration that the destination IMS AGW30FL3 is in the process of being configured and is in voice communication, it sets a value related to the source IMS AGW30FL.

[0324] S602: The P-CSCF 30G sends to the S-CSCF 30H a message (SIP re-INVITE) requesting an update of the voice communication state, including the termination point on the source IMS AGW 30FL side. For example, the message is expressed as SIP re-INVITE (PANI (access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID), PSI (satellite-type=LEO CONSTELLATION, satellite constellation id, satellite-id), SDP offer (c= the originating source satellite IMS AGW IP address, a=satellite-optimal-routing-capable)).

[0325] S603: The S-CSCF 30H transmits the message (SIP re-INVITE) received in S602 to the I-CSCF 30I.

[0326] S604: The I-CSCF 30I transmits the message (SIP re-INVITE) received in S603 to the S-CSCF 30H2.

[0327] S605: The S-CSCF 30H2 transmits the message (SIP re-INVITE) received in S604 to the P-CSCF 30G2.

[0328] S606: The P-CSCF 30G2 sends a message (SIP re-INVITE) to the terminal 20B requesting an update of the voice communication status, including the termination point on the IMS AGW 30FL2 side of its own network. For example, this message is expressed as SIP re-INVITE (SDP offer (c= the terminating satellite IMS AGW IP address)).

[0329] S607: The terminal 20B sends a success response (SIP 200 OK) to the P-CSCF 30G2. For example, this message is expressed as SIP 200 OK (PANI(access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID), SDP answer (c= the terminating UE IP address)).

[0330] S608: P-CSCF30G2 recognizes that both the source network and its own network are capable of routing over a satellite constellation, and recognizes that routing over a satellite constellation is possible because the satellite constellation ID of the source network and the satellite constellation ID of its own network are the same. Note that if the source network and its own network are the same network and P-CSCF30G2 has not received PSI, it may compare the PANI of the source terminal with the PANI of the destination terminal and recognize that routing over a satellite constellation is possible from the setting information stored locally.

[0331] S609: P-CSCF30G2 sends to S-CSCF30H2 a success response (SIP 200 OK) to the message received in S605. For example, the success response is expressed as SIP 200 OK (PANI (access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID), PSI (satellite-type=LEO CONSTELLATION, satellite constellation id, satellite-id), SDP answer (c= the terminating satellite IMS AGW IP address, a=satellite-optimal-routing-capable)).

[0332] S610: S-CSCF 30G2 transmits the success response (SIP 200 OK) received in S609 to I-CSCF 30I.

[0333] S611: The I-CSCF 30I transmits the success response (SIP 200 OK) received in S610 to the S-CSCF 30H.

[0334] S612: The S-CSCF 30H transmits the success response (SIP 200 OK) received in S611 to the P-CSCF 30G.

[0335] The process following S612 will be described. Fig. 19 is a diagram showing an example of a sixteenth sequence diagram according to an embodiment of the present invention. The process of each step will be described below.

[0336] S621: The P-CSCF 30G transmits to the IMS AGW 30FL3 a request message (H.248 MOD request) requesting settings related to (modification of) control of voice communication.

[0337] S622: The IMS AGW 30FL3 sets a termination point on the destination side for data transmission with the destination side.

[0338] S623: The IMS AGW 30FL3 transmits to the P-CSCF 30G a response message (H.248 MOD response) in response to the request message received in S621.

[0339] S624: The P-CSCF 30G transmits to the IMS AGW 30FL3 a request message (H.248 ADD request) requesting settings related to (addition of) voice communication control.

[0340] S625: The IMS AGW 30FL3 sets a terminal-side termination point for the data destined for the terminal, and requests acquisition of resources for the termination point on its own device side.

[0341] S626: The IMS AGW 30FL3 transmits to the P-CSCF 30G a response message (H.248 ADD response) in response to the request message received in S624. At this point, the setting of the destination IMS AGW 30FL3 is completed.

[0342] S627: Before indicating the termination point of the IMS AGW 30FL3 on the destination satellite to the terminal 20A, the P-CSCF 30G determines to set the termination point in the traffic filter of the ULCL 30E3.

[0343] S628: P-CSCF30G sends a request message (Npcf_PolicyAuthorization_Create request) to PCF30C requesting SMF30B to set the termination point of the destination IMS AGW30FL3 in the UL traffic filter for the destination L-UPF (UPF30D5L3).

[0344] S629: The PCF 30C transmits to the P-CSCF 30G a response message (Npcf_PolicyAuthorization_Create response) in response to the request message received in S628.

[0345] S630: The PCF 30C sends to the SMF 30B a request message (Npcf_SMPolicyControl_UpdateNotify request) requesting that the termination point of the destination IMS AGW 30FL3 be set in the UL traffic filter for the destination L-UPF (UPF 30D5L3).

[0346] S629: The SMF 30B sends to the PCF 30C a response message (Npcf_SMPolicyControl_UpdateNotify response) in response to the request message received in S630.

[0347] S632: The SMF 30B transmits to the ULCL 30E3 a request message (PFCP Session Modification request) requesting a packet forwarding setting update, the request message including information for setting the termination point of the destination IMS AGW 30FL3 as a UL traffic filter for the destination L-UPF (UPF 30D5L3). For example, the request message is expressed as PFCP Session Modification request (Traffic filter for UL to PSA5= the target satellite IMS AGW IP address, FAR=PSA5 UL TEID).

[0348] S633: ULCL 30E3 transmits to SMF 30B a response message (PFCP Session Modification response) to the request message received in S632.

[0349] S634: The P-CSCF 30G sends, to the terminal 20A, a message (SIP 200 OK) including information about the termination point on the destination IMS AGW 30FL3 side regarding data transmission with the terminal 20A. For example, this message is expressed as SIP 200 OK (SDP answer (c= the target satellite IMS AGW IP address)).

[0350] The current flow of data between UL and DL media will be described. Fig. 20 is a diagram showing an example of a seventeenth sequence diagram according to an embodiment of the present invention. The processing of each step will be described below.

[0351] As shown in S641, DL media (voice signals) are received via the source IMS AGW 30FL. That is, the DL media is received by the terminal 20A from the destination IMS AGW 30FL2 via the IMS AGW 30FL, the UPF 30D2L, the ULCL 30E, the ULCL 30E3, and the base station 10C.

[0352] As shown in S642, the UL media (voice signal) is transmitted via the destination IMS AGW 30FL3. That is, the UL media is transmitted from the terminal 20A to the IMS AGW 30FL2 on the receiving side via the base station 10C, the ULCL 30E3, the UPF 30D5L3, and the IMS AGW 30FL3.

[0353] As shown in S643, at this point in time, the IMS AGW 30FL2 on the receiving side does not transmit DL media (voice signals) to the IMS AGW 30FL3 of the destination.

[0354] The following describes the processing following S634 in Fig. 19. Fig. 21 is a diagram showing an example of an 18th sequence diagram according to an embodiment of the present invention. The processing of each step will be described below.

[0355] S650: Since the setting in the destination IMS AGW 30FL3 on the satellite has been completed, the P-CSCF 30G decides to transmit a notification (UPDATE) to the destination network side.

[0356] S651: The P-CSCF 30G sends to the S-CSCF 30H a message (UPDATE) requesting an update of the voice communication status, including information about the termination point on the destination IMS AGW 30FL3 side. For example, the message is expressed as UPDATE (PANI (access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID), PSI (satellite-type=LEO CONSTELLATION, satellite constellation id, satellite-id), SDP offer (c= the originating target satellite IMS AGW IP address, a=satellite-optimal-routing-capable)).

[0357] S652: The S-CSCF 30H transmits the message (UPDATE) received in S651 to the I-CSCF 30I.

[0358] S653: The I-CSCF 30I transmits the message (UPDATE) received in S652 to the S-CSCF 30H2.

[0359] S654: The S-CSCF 30H2 transmits the message (UPDATE) received in S653 to the P-CSCF 30G2.

[0360] S655: The P-CSCF 30G2 transmits to the IMS AGW 30FL2 a request message (H.248 MOD request) requesting settings related to (modification of) control of voice communication.

[0361] S656: The IMS AGW 30FL2 updates the setting of the originating termination point for the data destined for the originating network.

[0362] S657: The IMS AGW 30FL2 transmits to the P-CSCF 30G2 a response message (H.248 MOD response) in response to the request message received in S655.

[0363] S658: The P-CSCF 30G2 transmits the message (UPDATE) received in S654 to the terminal 20B. This message is expressed as UPDATE (SDP offer (c= the terminating satellite IMS AGW IP address)).

[0364] S659: The terminal 20B transmits to the P-CSCF 30G2 a response message (200 OK (UPDATE)) in response to the request message received in S658. For example, the response message is expressed as 200 OK (UPDATE) (PANI (access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID), SDP answer (c= the terminating UE IP address)).

[0365] S660: P-CSCF30G2 sends to S-CSCF30H2 a response message (200 OK (UPDATE)) in response to the message received in S654. For example, the response message is expressed as 200 OK (UPDATE) (PANI (access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID), PSI (satellite-type=LEO CONSTELLATION, satellite constellation id, satellite-id), SDP answer (c= the terminating satellite IMS AGW IP address, a=satellite-optimal-routing-capable)).

[0366] S661: The S-CSCF 30H2 transmits the message (200OK (UPDATE)) received in S660 to the I-CSCF 30I.

[0367] S662: The I-CSCF 30I transmits the message (200OK (UPDATE)) received in S661 to the S-CSCF 30H.

[0368] S663: The S-CSCF 30H transmits the message (200OK (UPDATE)) received in S662 to the P-CSCF 30G.

[0369] The current flow of data between UL and DL media will be described. Fig. 22 shows an example of a 19th sequence diagram according to an embodiment of the present invention. The processing of each step will be described below.

[0370] As shown in S671, UL media (voice signals) are transmitted via the destination IMS AGW 30FL3. That is, the UL media is transmitted from the terminal 20A to the IMS AGW 30FL2 on the receiving side via the base station 10C, ULCL 30E3, UPF 30D5L3, and IMS AGW 30FL3.

[0371] As shown in S672, DL media (voice signals) are received via the destination IMS AGW 30FL3. That is, the DL media is received by the terminal 20A from the destination IMS AGW 30FL2 via the IMS AGW 30FL3, the UPF 30D5L3, the ULCL 30E3, and the base station 10C.

[0372] By the above process, when switching from a communication device on a satellite from which the user moves to a communication device on a satellite at which the user moves, it is possible to perform seamless switching without interrupting the audio data.

[0373] According to the above-described embodiment, routing can be correctly performed after handover in a wireless communication system using a satellite.

[0374] (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.

[0375] <Base Station 10 and Network Node 30> Figure 23 is a diagram showing an example of the functional configuration of the base station 10 and the network node 30. As shown in Figure 23, 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 Figure 23 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.

[0376] 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.

[0377] 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.

[0378] 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.

[0379] <Terminal 20> Fig. 24 is a diagram showing an example of the functional configuration of the terminal 20. As shown in Fig. 24, 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. 24 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.

[0380] 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.

[0381] 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.

[0382] 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.

[0383] (Hardware Configuration) The block diagrams (FIGS. 23 and 24) 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.

[0384] 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.

[0385] 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. 25 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.

[0386] 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.

[0387] 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.

[0388] 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.

[0389] 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. 23 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. 24 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.

[0390] 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.

[0391] 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.

[0392] 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.

[0393] 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).

[0394] 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.

[0395] 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.

[0396] Fig. 26 shows an example configuration of a vehicle 2001. As shown in Fig. 26, 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.

[0397] 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.

[0398] 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).

[0399] 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.

[0400] 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.

[0401] 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.

[0402] 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.

[0403] 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.

[0404] 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.

[0405] 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.

[0406] <Supplementary Notes> In each supplementary note, the network node name and step number described in the embodiment are shown in parentheses. (Supplementary Note 1) A mobile station having a receiving unit that receives, from a first network node (=AMF30A), a first message requesting route switching accompanying a change of base station, including a satellite identifier of a satellite on which a destination base station is located, (S508) a control unit that recognizes that the satellite on which the source base station is located is different from the satellite on which the destination base station is located, (S509) a transmitting unit that transmits, to a second network node (=P-CSCF), a second message inquiring whether or not to switch an ULCL (Uplink Classifier) ​​(=ULCL30E) and a local user plane function (=UPF30D2L), and (S523, S525), wherein the receiving unit receives a third message that accepts the switching of the ULCL and the local user plane function transmitted from the second network node, and (S528, S530) the control unit sets the destination ULCL and the destination local user plane function, The transmitter transmits, to the second network node, a fourth message notifying the completion of switching between ULCL and local user plane function (S572, S574). Network node (=SMF30B). (Supplementary Item 2) The transmitter transmits, after transmitting the fourth message, a fifth message to the base station, requesting confirmation of a cell identifier by the terminal (S582, S584). The network node according to Supplementary Item 1. (Supplementary Item 3) A base station comprising: a receiver that receives, from the first network node (=AMF30A), a first message requesting confirmation of a cell identifier by the terminal (S584); and a transmitter that transmits, to the terminal, a second message requesting acquisition of system information of an accommodated cell and transmission of a measurement report (S588).(Supplementary Item 4) A terminal comprising: (S301) a transmitting unit that transmits to a first network node (=P-CSCF) a first message (=SIP INVITE) requesting the start of voice communication, including the cell identifier of the serving cell; (S302) a receiving unit that receives from a base station a second message requesting the acquisition of system information of the serving cell and the transmission of a measurement report; (S588) a control unit that checks the system information and recognizes that the cell identifier of the current serving cell is different from the cell identifier set in the first message; and (S590), wherein the transmitting unit transmits to the first network node a third message (=SIP re-INVITE) requesting an update of the voice communication status, including the cell identifier of the current serving cell. (Supplementary clause 5) A communication method executed by a network node, comprising the steps of: receiving from a first network node a first message requesting route switching accompanying a change of base station, the message including a satellite identifier of the satellite on which the destination base station is located; recognizing that the satellite on which the source base station is located is different from the satellite on which the destination base station is located; transmitting to a second network node a second message inquiring whether or not to switch the ULCL (Uplink Classifier) ​​and local user plane function; receiving from the second network node a third message approving the switch of the ULCL and local user plane function; setting the destination ULCL and the destination local user plane function; and transmitting to the second network node a fourth message notifying completion of the switch of the ULCL and local user plane function.

[0407] Any of Supplementary Items 1 to 5 makes it possible to correctly execute routing after handover in a wireless communication system using a satellite.

[0408] (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.

[0409] 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.

[0410] 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).

[0411] 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.

[0412] 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).

[0413] 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.

[0414] 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.

[0415] 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).

[0416] 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.

[0417] 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.

[0418] 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.

[0419] 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.

[0420] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0421] 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.

[0422] 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.

[0423] 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.

[0424] 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.

[0425] 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.

[0426] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," and the like may be used interchangeably.

[0427] 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.

[0428] 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.

[0429] 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.

[0430] 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.

[0431] 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.

[0432] 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.

[0433] The reference signal may be abbreviated as RS (Reference Signal) or may be called a pilot depending on the applicable standard.

[0434] 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."

[0435] 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.

[0436] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0437] 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.

[0438] 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.

[0439] 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."

[0440] 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).

[0441] 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.

[0442] 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 receiver that receives from a first network node a first message requesting route switching accompanying a change of base station, the message including the satellite identifier of the satellite on which the destination base station is located; a controller that recognizes that the satellite on which the source base station is located is different from the satellite on which the destination base station is located; and a transmitter that transmits to a second network node a second message inquiring whether or not to switch the ULCL (Uplink Classifier) ​​and local user plane function, wherein the receiver receives a third message transmitted from the second network node agreeing to switch the ULCL and local user plane function; the controller sets the destination ULCL and the destination local user plane function; and the transmitter transmits to the second network node a fourth message notifying the completion of switch of the ULCL and local user plane function.

2. The network node according to claim 1, wherein, after transmitting the fourth message, the transmitter transmits a fifth message addressed to the base station, requesting confirmation of a cell identifier by the terminal.

3. A base station having: a receiving unit that receives a first message from a first network node, the first message requesting confirmation of a cell identifier by a terminal; and a transmitting unit that transmits a second message to the terminal, the second message requesting acquisition of system information of a serving cell and transmission of a measurement report.

4. A terminal comprising: a transmitter that transmits to a first network node a first message requesting the start of voice communication, the message including the cell identifier of the serving cell; a receiver that receives from a base station a second message requesting the acquisition of system information of the serving cell and the transmission of a measurement report; and a controller that checks the system information and recognizes that the cell identifier of the current serving cell is different from the cell identifier set in the first message, wherein the transmitter transmits to the first network node a third message requesting an update of the voice communication status, the third message including the cell identifier of the current serving cell.

5. A communication method executed by a network node, comprising the steps of: receiving from a first network node a first message requesting route switching accompanying a change of base station, the message including the satellite identifier of the satellite on which the destination base station is located; recognizing that the satellite on which the source base station is located is different from the satellite on which the destination base station is located; sending to a second network node a second message inquiring whether or not to switch the ULCL (Uplink Classifier) ​​and local user plane function; receiving from the second network node a third message approving the switch of the ULCL and local user plane function; setting the destination ULCL and the destination local user plane function; and sending to the second network node a fourth message notifying completion of the switch of the ULCL and local user plane function.

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