Network node and communication method

Abstract

In a satellite-based wireless communication system, the objective is to implement ground fallback routing via the ground during satellite switching without changing the existing P-CSCF specifications. [Solution] The network node includes a receiving unit that receives information from a first network node about a satellite to which a new terminal will be accommodated; a control unit that determines that it is impossible to set an optimal inter-satellite route based on information about a satellite to which a terminal on the other network side will be accommodated and information about a satellite to which a terminal on the local network side will be accommodated; and a transmitting unit that sends to a second network node a first message requesting a change in voice call settings, which includes information requesting the setting of a ground-based route to a third network node of the local network, and a second message requesting a change in voice call settings, which includes information requesting the setting of a ground-based route to a fourth network node of the other network.

Description

Technical Field

[0001] The present invention relates to a network node and a communication method in a communication system.

Background Art

[0002] In 3GPP (Registered Trademark) (3rd Generation Partnership Project), in order to achieve further increase in system capacity, further increase in data transmission speed, further reduction in latency in the radio section, etc., a wireless communication method called 5G or NR (New Radio) (hereinafter, this wireless communication method is referred to as "5G" or "NR") is being studied. In 5G, various wireless technologies are being studied to meet the requirement of achieving a throughput of 10 Gbps or more and reducing the latency in the radio section to 1 ms or less.

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

[0004] Furthermore, the specifications for an IMS (IP Multimedia Subsystem) network are being considered as an IMS architecture to support the data channel capabilities of terminals (see, for example, Non-Patent Document 2). In an IMS data channel network, a DCSF (Data Channel Signaling Function) with signaling capabilities, an MF (Media Function) with media-related functions, and a DCAS (Data Channel Application Server) which is an application server are deployed on both the sending and receiving ends.

[0005] Furthermore, in 3GPP Rel-19, a challenge in realizing IMS voice terminal-satellite-UE communication is reducing the impact on existing specifications when deploying 5GC network functions and IMS components on satellites (see, for example, Non-Patent Document 3). Here, terminal-satellite-UE communication refers to terminal-to-terminal communication under routing that keeps user plane traffic within the satellite. The types of satellites dealt with are geostationary Earth Orbit (GEO), low Earth Orbit (LEO), and medium Earth Orbit (MEO). In addition, for low Earth Orbit and medium Earth Orbit satellites, there are cases where a satellite constellation is formed without using inter-satellite links (ISL), and cases where a satellite constellation is formed using inter-satellite links. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] 3GPP TS 23.501 V18.5.0(2024-06) [Non-Patent Document 2] 3GPP TS 23.228 V18.6.0(2024-06) [Non-Patent Document 3] 3GPP TR23.700-29 V19.0.0(2024-06) [Non-Patent Document 4] 3GPP TS 38.331 V18.0.0(2023-12) [Non-Patent Document 5] 3GPP TS 38.413 V18.0.0(2023-12) [Non-Patent Document 6] 3GPP TS 23.502 V18.7.0(2024-06) [Non-Patent Document 7] 3GPP TS 29.512 V18.7.0(2024-09) [Non-Patent Document 8] 3GPP TS 29.514 V18.7.0(2024-09) [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In 3GPP, for satellite constellation communications using satellite-based IMS access gateways (IMS AGWs), the configuration of terminal-to-terminal communication (terminal-satellite-terminal) via satellite for voice calls, and the switching of satellite-based IMS AGWs due to satellite movement are being considered. In this case, if voice media (voice data) cannot be routed on the satellite, ground fallback is performed, which routes the data via the ground.

[0008] However, the method currently under consideration requires adding functionality to network nodes with proxy capabilities (Proxy-Call Session Control Function, P-CSCF) and modifying the existing specifications of the P-CSCF.

[0009] This invention has been made in view of the above points, and aims to enable ground fallback routing via the ground during satellite switching in a satellite-based wireless communication system without changing the existing specifications of P-CSCF. [Means for solving the problem]

[0010] According to the disclosed technology, a network node is provided which includes: a receiving unit that receives information from a first network node about a satellite to which a terminal will be newly accommodated; a control unit that determines that it is impossible to set an optimal inter-satellite route based on information about a satellite to which a terminal on the other network side will be newly accommodated and information about a satellite to which a terminal on the local network side will be newly accommodated; and a transmitting unit that sends to a second network node a first message requesting a change in voice call settings, which includes information requesting the setting of a ground-based route to a third network node of the local network, and a second message requesting a change in voice call settings, which includes information requesting the setting of a ground-based route to a fourth network node of another network. [Effects of the Invention]

[0011] According to the disclosed technology, in a satellite-based wireless communication system, ground fallback routing via the ground can be performed during satellite switching without changing the existing P-CSCF specifications. [Brief explanation of the drawing]

[0012] [Figure 1] This is a diagram illustrating an example of a communication system. [Figure 2] This diagram illustrates an example of a communication system in a roaming environment. [Figure 3] This diagram illustrates an example of an IMS data channel network. [Figure 4] This figure shows an example of a first sequence diagram in an embodiment of the present invention. [Figure 5] This figure shows an example of a second sequence diagram in an embodiment of the present invention. [Figure 6] This figure shows an example of a third sequence diagram in an embodiment of the present invention. [Figure 7] This figure shows an example of a fourth sequence diagram in an embodiment of the present invention. [Figure 8]This is a diagram showing an example of a fifth sequence diagram in an embodiment of the present invention. [Figure 9] This is a diagram showing an example of the functional configuration of base station 10 and network node 30 in an embodiment of the present invention. [Figure 10] This is a diagram showing an example of the functional configuration of terminal 20 in an embodiment of the present invention. [Figure 11] This is a diagram showing an example of the hardware configuration of base station 10, terminal 20, and network node 30 in an embodiment of the present invention. [Figure 12] This is a diagram showing an example of the configuration of vehicle 2001 in an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are examples, and the embodiments to which the present invention is applied are not limited to the following embodiments.

[0014] In the operation of the wireless communication system according to the embodiment of the present invention, existing technologies are appropriately used. However, the existing technology is, for example, existing LTE, but is not limited to existing LTE. Further, the term "LTE" used in this specification has a broad meaning including LTE-Advanced, and systems after LTE-Advanced (e.g., NR), or wireless LAN (Local Area Network) unless otherwise specified.

[0015] Also, in the embodiment of the present invention, when wireless parameters or the like are "configured", it may mean that predetermined values are pre-configured, or wireless parameters notified from network node 30 or terminal 20 are configured.

[0016] Figure 1 is a diagram illustrating an example of a communication system. As shown in Figure 1, the communication system consists of a terminal 20 (UE) and multiple network nodes 30. Hereafter, one network node 30 will be assigned to each function, however, one network node 30 may implement multiple functions, or multiple network nodes 30 may implement 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 radio access functionality, which may include a base station 10, and is connected to the UE, AMF (Access and Mobility Management Function), and 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), registration management, connection management, reachability management, and terminal mobility management. The UPF is a network node 30 interconnected with the DN (Data Network) and having functions related to processing user plane data, such as PDU (Protocol Data Unit) session points to the outside, packet routing and forwarding, and user plane QoS (Quality of Service) handling. The UPF and DN constitute a network slice. In the wireless communication network in the embodiment of the present invention, multiple network slices are constructed.

[0018] AMF is connected to 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). AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are interconnected via interfaces based on their respective services: Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

[0019] SMF is a network node 30 that has functions such as session management, IP (Internet Protocol) address allocation and management for UEs, DHCP (Dynamic Host Configuration Protocol) functionality, ARP (Address Resolution Protocol) proxy, and roaming functionality. NEF is a network node 30 that has the function of notifying other NFs (Network Functions) of capabilities and events. NSSF is a network node 30 that has functions such as selecting the network slice to which the UE connects, determining the allowed NSSAI (Network Slice Selection Assistance Information), determining the NSSAI to be set, and determining the AMF set to which the UE connects. PCF is a network node 30 that has the function of controlling network policy. AF is a network node 30 that has the function of controlling application servers. NRF is a network node 30 that has the function of discovering NF instances that provide services. UDM is a network node 30 that manages subscriber data and authentication data. UDM is connected to UDR (User Data Repository) which holds the said data.

[0020] Figure 2 is a diagram illustrating an example of a communication system in a roaming environment. As shown in Figure 2, the network consists of a terminal 20 (UE) and multiple network nodes 30. Hereafter, one network node 30 will be assumed to correspond to each function, however, one network node 30 may implement multiple functions, or multiple network nodes 30 may implement one function. Furthermore, the "connection" described below may be a logical connection or a physical connection.

[0021] The RAN is a network node 30 with wireless access capabilities and is connected to the UE, AMF, and UPF. The AMF is a network node 30 with functions such as RAN interface termination, NAS termination, registration management, connection management, reachability management, and mobility management. The UPF is a network node 30 interconnected with the DN and has functions such as external PDU session point, packet routing and forwarding, and user plane QoS handling. The UPF and DN constitute a network slice. In the wireless communication network according to the embodiment of the present invention, multiple network slices are constructed.

[0022] AMF is connected to UE, RAN, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, AF, and SEPP (Security Edge Protection Proxy). AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are interconnected via interfaces based on their respective services: Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

[0023] SMF is a network node 30 with functions such as session management, UE IP address assignment and management, DHCP functionality, ARP proxy, and roaming functionality. NEF is a network node 30 with the function of notifying other NFs of capabilities and events. NSSF is a network node 30 with functions such as selecting the network slice to which the UE connects, determining the allowed NSSAI, determining the NSSAI to be configured, and determining the AMF set to which the UE connects. PCF is a network node 30 with the function of controlling network policy. AF is a network node 30 with the function of controlling application servers. NRF is a network node 30 with the function of discovering NF instances that provide services. SEPP is an opaque proxy that filters control plane messages between PLMNs (Public Land Mobile Networks). vSEPP shown in Figure 2 is SEPP in the visited network, and hSEPP is SEPP in the home network.

[0024] As shown in Figure 2, the UE is in a roaming environment connected to the RAN and AMF in the VPLMN (Visited PLMN). The VPLMN and HPLMN (Home PLMN) are connected via vSEPP and hSEPP. The UE can communicate with the HPLMN's UDM, for example, via the VPLMN's AMF.

[0025] Figure 3 is a diagram illustrating an example of an IMS data channel network. As shown in Figure 3, the IMS data channel network consists of a terminal 20 (UE) and multiple network nodes 30 in both the originating network and the terminating network. Hereafter, one network node 30 will be assumed to correspond to each function, however, one network node 30 may implement multiple functions, or multiple network nodes 30 may implement 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 as described in Non-Patent Literature 2.

[0026] The IMS-AGW (Access Gateway) is a network node 30 that has the functions of a gateway between the UE and the IMS network, as well as functions related to voice communication access processing.

[0027] P-CSCF (Proxy-Call Session Control Function) is a network node 30 that has proxy functions between the UE and the IMS network, as well as access control functions for voice communications.

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

[0029] The I-CSCF (Interrogate-Call Session Control Function) is a network node 30 that is the connection point on the receiving side between networks in the IMS network (for example, the sending side and the receiving side), and has functions such as forwarding received SIP requests to the S-CSCF of its own network.

[0030] The IMS AS (IP Multimedia Subsystem Application Server) is a network node 30 in the IMS network that has functions such as communicating with the DCSF for event notification and receiving data channel control instructions from the DCSF and communicating with the MF. The IMS AS also receives a registration request for the communication termination point from the DCSF (Data Channel Signaling Function), converts the received registration request into a SIP Register, and sends it to the S-CSCF (Serving-Call Session Control Function). Furthermore, the IMS AS converts a data channel establishment request received from the DCSF into a SIP INVITE and sends it to the S-CSCF.

[0031] DCSF (Data Channel Signaling Function) is a network node 30 that has functions such as receiving event reports from IMS-AS and deciding whether or not to allow the provision of data channel services, managing bootstrap data channels, and HTTP web server functionality.

[0032] The Media Function (MF) is a network node 30 in the IMS network that has functions such as media resource management and data channel media traffic forwarding. The MF also processes media between the Data Channel Application Server (DCAS), which is the communication termination point, and the destination termination point based on configuration information received from the Data Channel Application Server (DCSF). The MF may also be called the Data Channel Media Function (DCMF). The MF may also be called the Multimedia Resource Function (MRF).

[0033] DCAS (Data Channel Application Server) is a network node 30 that has functions such as being a communication termination point for media and signaling in the IMS network.

[0034] (Examples) This document describes a procedure for implementing ground fallback routing via the ground during satellite switching in a satellite-based wireless communication system, without changing the existing P-CSCF specifications.

[0035] In this embodiment, it is assumed that a base station, an ULCL (Uplink Classifier), and multiple low-Earth orbit (LEO) satellites equipped with UPFs form a satellite constellation using an inter-satellite link (ISL). The ULCL has the function of selectively distributing uplink traffic between N9 interfaces.

[0036] Satellite communications operators primarily prepare base stations, ULCLs, UPFs deployed on LEOs, and ground-based intermediary equipment that communicates with satellite devices as dedicated equipment for satellite constellation communications. On the other hand, mobile communications operators primarily prepare network nodes deployed on the ground, such as AMFs and SMFs, as equipment for satellite constellation utilization.

[0037] In this embodiment, an IMS application server for satellite use (referred to as SAT IMS AS) is introduced, and three sessions are configured for terminal-to-terminal communication: between the originating terminal and the originating network SAT IMS AS, between the originating network SAT IMS AS and the receiving network SAT IMS AS, and between the receiving network SAT IMS AS and the receiving terminal.

[0038] The SAT IMS AS determines whether or not terminal-to-terminal communication via satellite is possible. If it determines that it is possible, the ULCL, local UPF, and IMS AGW are configured based on instructions from the SAT IMS AS.

[0039] S-CSCF receives filter criteria from the HSS (Home Subscriber Server) for subscribers authorized to communicate with terminals via satellite, which are the settings for data transfer to the SAT IMS AS. The HSS is a network node that manages subscriber information, etc.

[0040] The details of the processing in this embodiment will be explained below using a sequence diagram. Requests, responses, and notifications sent and received in the following procedures may be referred to as messages (for example, request messages). For details regarding existing specifications concerning the messages sent and received in this sequence diagram, please refer to Non-Patent Document 4-8, etc.

[0041] On the transmitting side, AMF30A, SMF30B, PCF30C, P-CSCF30G, S-CSCF30H, SAT IMS AS30X, HSS30J, remote IMS AGW30FR, and remote UPF(R-PSA1)30D1R, which is the first termination point (PDU Session Anchor 1, PSA1) of the PDU session, are deployed on the ground. Here, UPF may be referred to as the termination point of the PDU session; for example, UPF(R-PSA1)30D1R may be referred to as UPF30D1R or PSA1. On the other hand, on the satellite to which terminal 20A is connected, base station 10A, ULCL30E, local IMS AGW30FL, and local UPF(L-PSA2)30D2L, which is the second termination point (PSA2) of the PDU session, are deployed.

[0042] In this sequence, after voice communication using satellites is established between terminal 20A, the transmitting terminal, and terminal 20B, the receiving terminal, a handover is performed by switching the satellite to which terminal 20A is connected. At this point, the destination satellite is equipped with base station 10C, ULCL30E3, local IMS AGWFL3, and local UPF(L-PSA3)30D3L3, which is the third termination point (PSA3) of the PDU session.

[0043] On the receiving end, AMF30A2, SMF30B2, PCF30C2, P-CSCF30G2, S-CSCF30H2, SAT IMS AS30X2, HSS30J2, remote IMS AGW30FR2, and remote UPF(R-PSA4)30D4R, which is the fourth termination point (PSA4) of the PDU session, are deployed on the ground. Meanwhile, on the satellite to which terminal 20B is connected, base station 10B, ULCL30E2, local IMS AGW30FL2, and local UPF(L-PSA5)30D5L, which is the fifth termination point (PSA5) of the PDU session, are deployed.

[0044] (satellite movement) The procedure for satellite transfer in which the satellite housing the calling terminal 20A switches to another satellite after a voice call via the IMS AGW on the satellite is completed will be described. Figure 4 shows an example of a first sequence diagram in an embodiment of the present invention. The sequence diagram in Figure 4 is the Xn handover procedure. The processing of each step will be described below.

[0045] S101: Base station 10A sends a Handover Request to base station 10C.

[0046] S102: Base station 10C sends a Handover Request Acknowledgement, which includes a Handover Command, to base station 10A as a response to the Handover Request received in S101.

[0047] S103: Base station 10A sends a message (RRCReconfiguration) to terminal 20A requesting the execution of settings related to radio resource control (RRC). This message includes a handover command.

[0048] S104: Base station 10A sends an SN status transfer to base station 10C.

[0049] S105: Terminal 20A sends a message to base station 10C notifying it that the RRC configuration is complete. This message includes a handover confirmation command.

[0050] S106: Base station 10C sends a request message (Path Switch request) to AMF30A requesting a route change due to the base station change.

[0051] S107: Based on the previously recognized correspondence between the transport layer settings and the source base station identifier, and the transport layer settings and base station identifier of the request message received in S106, the AMF30A recognizes the satellite constellation identifier and satellite identifier currently accommodating terminal 20A, and recognizes that the satellite with the satellite identifier is accommodating terminal 20A.

[0052] S108: AMF30A sends a request message (Nsmf_PDUSession_UpdateSMContext request) to SMF30B requesting route switching due to the base station change. This request message includes a satellite constellation identifier and a satellite identifier, and is written as, for example, Nsmf_PDUSession_UpdateSMContext request (SmContextUpdateData (satellite constellation id, satellite id)).

[0053] S109: SMF30B sends a request message (PFCP Session Modification request) to ULCL30E for updating the user data transfer path.

[0054] S110:ULCL30E sends a response message (PFCP Session Modification response) to SMF30B for the request message received in S109.

[0055] S111: SMF30B sends a response message (Nsmf_PDUSession_UpdateSMContext response) to AMF30A for the request message received in S108.

[0056] S112: The AMF30A sends a response message (Path Switch request response) to the base station 10C in response to the request message received in S106.

[0057] S113: Base station 10C sends a message to base station 10A requesting the release of the terminal context (UE Context Release).

[0058] The process following S113 will now be described. In the subsequent processes, the switching between ULCL and UPF on the satellite is performed. Figure 5 is a diagram showing an example of a second sequence diagram in an embodiment of the present invention. The process of each step will be described below.

[0059] S201: SMF30B recognizes the change in base station 10B and the change in satellite identifier based on the request message received in S108 in Figure 4.

[0060] S202:SMF30B sends a request message (Npcf_SMPolicyControl_Update request) to PCF30C requesting an update of satellite information. This request message includes information about the new satellite to which terminal 20A will be located (satellite constellation identifier and satellite identifier), and is written as, for example, Npcf_SMPolicyControl_Update request (SmPolicyUpdateContextData (satelliteInfo (satellite constellation id, satellite id))).

[0061] S203: PCF30C sends a response message (Npcf_SMPolicyControl_Update response) to SMF30B for the request message received in S202.

[0062] S204:PCF30C sends a request message (Npcf_PolicyAuthorization_Notify request) to SAT IMS AS30X to notify it of information about the satellite. This request message includes information about the new satellite to which terminal 20A will be located (satellite constellation identifier and satellite identifier), and is written as, for example, Npcf_PolicyAuthorization_Notify request (EventsNotification (evNotifs (event= ANI_REPORT), satelliteInfo(satellite constellation id, satellite id))).

[0063] S205: SAT IMS AS30X sends a response message (Npcf_PolicyAuthorization_Notify response) to PCF30C for the request message received in S604.

[0064] S206: SAT IMS AS30X recognizes that the destination satellite belongs to a different satellite constellation than the satellite accommodating the arrival terminal 20B, that is, after the ULCL and UPF switchover, the satellite constellations of the departure and arrival terminals are different, and determines that it is impossible to set an optimal inter-satellite route.

[0065] S207: SAT IMS AS30X sends a message (SIP re-INVITE) to S-CSCF30H requesting a change in voice call settings, which includes information (a=ground fallback-requested) requesting the establishment of a ground-based route for P-CSCF30G on its own network. For example, this message is written as SIP re-INVITE (PSI(satellite constellation id, satellite-id), SDP offer (c=dummy, a=ground fallback-requested)).

[0066] S208: S-CSCF30H sends the message received in S207 (SIP re-INVITE) to P-CSCF30G.

[0067] S209: Based on the message (SIP re-INVITE) received in S208, P-CSCF30G decides to select the ground-based IMS AGW30FR and perform the configuration of IMS AGW30FR.

[0068] S210:P-CSCF30G sends a request message (H.248 ADD request) to IMS AGW30FR requesting settings related to (additional) control of voice communication.

[0069] S211: IMS AGW30FR acquires and configures the resources of the termination point on its own device side for data transmission with the originating side.

[0070] S212: IMS AGW30FR sends a response message (H.248 ADD response) to P-CSCF30G for the request message received in S210.

[0071] S213:P-CSCF30G sends a message (SIP re-INVITE) to terminal 20A requesting a change in voice call settings. This message includes the IP address of the termination point of the originating satellite IMS AGW30FL in the negotiation offer (SDP offer). For example, this message is written as SIP re-INVITE (SDP offer (c= the originating source satellite IMS AGW IP address)).

[0072] S214: Terminal 20A sends a response message (SIP 200 OK) to P-CSCF30G for the message received in S213. This message includes the IP address of terminal 20A's endpoint in the negotiation response (SDP answer), and is written as, for example, SIP 200 OK (SDP answer (c= the originating UE IP address)).

[0073] S215:P-CSCF30G sends a request message (H.248 MOD request) to IMS AGW30FR requesting settings related to the control (or modification) of voice communication.

[0074] S216: IMS AGW30FR sets the originating side termination point for data transmission with the originating side.

[0075] S217: IMS AGW30FR sends a response message (H.248 MOD response) to P-CSCF30G for the request message received in S215.

[0076] S218:P-CSCF30G sends a request message (H.248 ADD request) to IMS AGW30FR requesting settings related to (additional) control of voice communication.

[0077] S219: The IMS AGW30FR sets the destination termination point for data transmission with the destination device and acquires resources for the termination point on its own device side.

[0078] S220: IMS AGW30FR sends a response message (H.248 ADD response) to P-CSCF30G for the request message received in S218.

[0079] The process following S220 will now be described. Figure 6 is a diagram showing an example of a third sequence diagram in an embodiment of the present invention. The process of each step will be described below.

[0080] S221:P-CSCF30G sends a response message (SIP 200 OK) to S-CSCF30H. This message includes the IP address of the originating ground IMS AGW30FR termination point used by the receiving side in the negotiated response (SDP answer), and is written as, for example, SIP 200 OK (SDP answer (c= the originating ground IMS AGW IP address used by the terminating side)).

[0081] S222: S-CSCF30H sends the response message received in S221 (SIP 200 OK) to SAT IMS AS30X.

[0082] S223:P-CSCF30G decides to revise the filter criteria for terminal 20A.

[0083] S224:P-CSCF30G sends a request message (Npcf_PolicyAuthorization_Update request) to PCF30C requesting that the terminal's packet filter, which identifies voice media and associates them with QoS flows, add the originating ground IMS AGW30FR termination point as a destination. This request message includes the IP address of the originating ground IMS AGW30FR termination point, which is configured on the terminal as the destination for voice media. For example, the message is written as Npcf_PolicyAuthorization_Update request (the originating ground IMS AGW IP address used by UE).

[0084] S225: PCF30C sends a response message (Npcf_PolicyAuthorization_Update response) to P-CSCF30G for the request message received in S224.

[0085] S226:PCF30C sends a request message (Npcf_SMPolicyControl_UpdateNotify request) to SMF30B requesting that the terminal's packet filter, which identifies voice media and associates them with QoS flows, add the originating ground IMS AGW30FR termination point as a destination. This request message includes the IP address of the originating ground IMS AGW30FR termination point, which is configured on the terminal as the destination for voice media. For example, the message is written as Npcf_SMPolicyControl_UpdateNotify request (the originating ground IMS AGW IP address used by UE).

[0086] S227: SMF30B sends a response message (Npcf_SMPolicyControl_UpdateNotify response) to PCF30C for the request message received in S226.

[0087] S228: SMF30B sends a request message (Namf_Communication_N1N2MessageTransfer request) to AMF30A for updating the PDU session settings. For example, this message is written as Namf_Communication_N1N2MessageTransfer request (N1N2MessageTransferReqData (n1MessageContainer(n1MessageContent(PDU Session Modification Command)))).

[0088] S229: AMF30A sends a response message (Namf_Communication_N1N2MessageTransfer response) to SMF30B for the request message received in S228.

[0089] S230:AMF30A sends a message (DownlinkNAS Transport) to base station 10C that contains information indicating a request for updating the PDU session settings. For example, this message is written as DownlinkNAS Transport(NAS-PDU(DL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Command)))).

[0090] S231: Base station 10C sends a message (DLInformationTransfer) to terminal 20A containing information indicating a request for updating the PDU session resource settings. For example, the message is written as DLInformationTransfer(dedicatedNAS-Message(DL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Command)))).

[0091] S232: Terminal 20A sends a message (ULInformationTransfer) to base station 10C that contains information indicating the completion of the PDU session resource configuration update requested by the message received in S231. For example, the message is written as ULInformationTransfer(dedicatedNAS-Message(UL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Complete)))).

[0092] S233: Base station 10C sends a message (Uplink NAS Transport) to AMF30A containing information indicating the completion of the PDU session resource configuration update received in S232. For example, the message is written as Uplink NAS Transport(NAS-PDU(UL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Complete)))).

[0093] S234: AMF30A sends a message to SMF30B containing information indicating the completion of the PDU session resource configuration update received in S233 (Nsmf_PDUSession_UpdateSMContext request). For example, this message is written as Nsmf_PDUSession_UpdateSMContext request (SmContextUpdateData(n1SmMsg(PDU Session Modification Complete))).

[0094] S235: SMF30B sends a response message (Nsmf_PDUSession_UpdateSMContext response) to AMF30A for the request message received in S234.

[0095] S236: SAT IMS AS30X decides to trigger ground fallback on the landing side.

[0096] S237: SAT IMS AS30X sends a message (SIP re-INVITE) to S-CSCF30H requesting a change in voice call settings, which includes information (a=ground fallback-requested) requesting the establishment of a ground-based route for P-CSCF30G2, which is located in the network. For example, this message is written as SIP re-INVITE (PSI(satellite constellation id, satellite-id), SDP offer (c=the originating ground IMS AGW IP address, a=ground fallback-requested)).

[0097] S238: S-CSCF30H sends the message received in S237 (SIP re-INVITE) to P-CSCF30G.

[0098] The process following S238 will now be described. Figure 7 is a diagram showing an example of a fourth sequence diagram in an embodiment of the present invention. The process of each step will be described below.

[0099] S241: I-CSCF30I sends the message (SIP re-INVITE) received in S238 in Figure 6 to S-CSCF30H2.

[0100] S242: S-CSCF30H2 sends the message received in S241 (SIP re-INVITE) to SAT IMS AS30X2.

[0101] S243: SAT IMS AS30X2 sends the message received in S242 (SIP re-INVITE) to S-CSCF30H2.

[0102] S244: S-CSCF30H2 sends the message received in S243 (SIP re-INVITE) to P-CSCF30G2.

[0103] S245: P-CSCF30G2 decides to configure the ground IMS AGW30FR2 based on the information (a=ground fallback-requested) in the message (SIP re-INVITE) received in S244 that requests the establishment of a ground-based route.

[0104] S246:P-CSCF30G2 sends a request message (H.248 ADD request) to IMS AGW30FR2 requesting settings related to (additional) control of voice communication.

[0105] S247: IMS AGW30FR2 acquires and sets the resources of the termination point on its own device side for data transmission with the originating side.

[0106] S248: IMS AGW30FL3 sends a response message (H.248 ADD response) to P-CSCF30G2 for the request message received in S246.

[0107] S249:P-CSCF30G2 sends a message (SIP re-INVITE) to terminal 20B requesting a voice call configuration change, including the setting to send voice media to the IMS AGW on satellite. The message includes the IP address of the termination point of the receiving satellite IMS AGW30FL2 in the negotiating offer (SDP offer). For example, the message is written as SIP re-INVITE (SDP offer (c= the terminating satellite IMS AGW IP address)).

[0108] S250: Terminal 20B sends a response message (SIP 200 OK) to P-CSCF30G2 for the message received in S249. For example, the message is written 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)).

[0109] S251:P-CSCF30G2 sends a request message (H.248 MOD request) to IMS AGW30FR2 requesting settings related to the control (or modification) of voice communication.

[0110] S252: IMS AGW30FR2 sets the originator termination point for data transmission with the originator.

[0111] S253: IMS AGW30FR2 sends a response message (H.248 MOD response) to P-CSCF30G2 for the request message received in S251.

[0112] S254:P-CSCF30G2 sends a request message (H.248 ADD request) to IMS AGW30FR2 requesting settings related to (additional) control of voice communication.

[0113] S255: IMS AGW30FR2 sets the destination termination point for data transmission with the destination device and acquires resources for the termination point on its own device side.

[0114] S256: IMS AGW30FR2 sends a response message (H.248 ADD response) to P-CSCF30G2 for the request message received in S254.

[0115] S257:P-CSCF30G2 decides to revise the filter criteria for terminal 20B.

[0116] S258: P-CSCF30G2 sends a request message (Npcf_PolicyAuthorization_Update request) to PCF30C2 requesting that the terminal's packet filter, which identifies voice media and associates them with QoS flows, add the termination point of the ground IMS AGW30FR2 as a destination. This request message includes the IP address of the originating ground IMS AGW30FR2 termination point, which is configured on the terminal as the destination for voice media. For example, the message is written as Npcf_PolicyAuthorization_Update request (the terminating ground IMS AGW IP address used by UE).

[0117] S259: PCF30C2 sends a response message (Npcf_PolicyAuthorization_Update response) to P-CSCF30G2 for the request message received in S258.

[0118] S260:PCF30C2 sends a request message (Npcf_PolicyAuthorization_Update request) to SMF30B2 requesting that the terminal's packet filter, which identifies voice media and associates them with QoS flows, add the termination point of the ground IMS AGW30FR2 as a destination. This request message includes the IP address of the originating ground IMS AGW30FR2 termination point, which is configured on the terminal as the destination for voice media. For example, this message is written as Npcf_SMPolicyControl_UpdateNotify request (the terminating ground IMS AGW IP address used by UE).

[0119] S261: SMF30B2 sends a response message (Npcf_SMPolicyControl_UpdateNotify response) to PCF30C2 for the request message received in S260.

[0120] S262: SMF30B2 sends a request message (Namf_Communication_N1N2MessageTransfer request) to AMF30A2 for updating the PDU session settings. For example, this message is written as Namf_Communication_N1N2MessageTransfer request (N1N2MessageTransferReqData (n1MessageContainer(n1MessageContent(PDU Session Modification Command)))).

[0121] S263: AMF30A2 sends a response message (Namf_Communication_N1N2MessageTransfer response) to SMF30B2 for the request message received in S262.

[0122] S264:AMF30A2 sends a message (DownlinkNAS Transport) to base station 10B that contains information indicating a request for updating the PDU session settings. For example, this message is written as DownlinkNAS Transport(NAS-PDU(DL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Command)))).

[0123] S265: Base station 10B sends a message (DLInformationTransfer) to terminal 20B that contains information indicating a request for updating the PDU session resource settings. For example, the message is written as DLInformationTransfer(dedicatedNAS-Message(DL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Command)))).

[0124] S266: Terminal 20B sends a message (ULInformationTransfer) to base station 10B containing information indicating the completion of the PDU session resource configuration update requested by the message received in S265. For example, the message is written as ULInformationTransfer(dedicatedNAS-Message(UL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Complete)))).

[0125] S267: Base station 10B sends a message (Uplink NAS Transport) to AMF30A2 containing information indicating the completion of the PDU session resource configuration update received in S266. For example, the message is written as Uplink NAS Transport(NAS-PDU(UL NAS transport(Payload container type(N1 SM information), Payload container(PDU Session Modification Complete)))).

[0126] S268: AMF30A2 sends a message to SMF30B2 containing information indicating the completion of the PDU session resource configuration update received in S267 (Nsmf_PDUSession_UpdateSMContext request). For example, this message is written as Nsmf_PDUSession_UpdateSMContext request (SmContextUpdateData(n1SmMsg(PDU Session Modification Complete))).

[0127] S269: SMF30B sends a response message (Nsmf_PDUSession_UpdateSMContext response) to AMF30A for the request message received in S268.

[0128] S270:P-CSCF30G2 sends the response message (SIP 200 OK) received by S250 to S-CSCF30H2. For example, the message is written 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 ground IMS AGW address)).

[0129] S271: S-CSCF30H2 sends the response message (SIP 200 OK) received by S270 to SAT IMS AS30X2.

[0130] S272: SAT IMS AS30X2 sends the response message (SIP 200 OK) received in S271 to S-CSCF30H2.

[0131] S273: S-CSCF30H2 sends the response message (SIP 200 OK) received in S272 to I-CSCF30I.

[0132] The process following S273 will now be described. Figure 8 is a diagram showing an example of a fifth sequence diagram in an embodiment of the present invention. The process of each step will be described below.

[0133] S281: I-CSCF30I sends the response message (SIP 200 OK) received in S273 in Figure 7 to S-CSCF30H.

[0134] S282: S-CSCF30H sends the response message (SIP 200 OK) received in S281 to SAT IMS AS30X.

[0135] S283: SAT IMS AS30X recognizes that the configuration of the ground IMS AGW30FR2 is complete and decides to send another SIP re-INVITE to the originating ground IMS AGW30FR and terminal 20A to update the destination for voice data transmission.

[0136] S284: SAT IMS AS30X sends a message (SIP re-INVITE) to S-CSCF30H requesting a change in voice call settings, which includes information (a=ground fallback-requested-to-fixedpart) requesting that voice data be sent to the ground IMS AGW. For example, the message is written as SIP re-INVITE (PSI(satellite constellation id, satellite-id), SDP offer (c=the terminating satellite IMS AGW IP address, a=ground fallback-requested-to-fixedpart)).

[0137] S285: S-CSCF30H sends the message received in S284 (SIP re-INVITE) to P-CSCF30G.

[0138] S286: P-CSCF30G decides to update the ground fallback settings on the terminal and the originating IMS AGW30FR, etc., based on the information (a=ground fallback-requested-to-fixedpart) contained in the message received in S285 that requests the transmission of voice data to the ground IMS AGW.

[0139] S287: If the P-CSCF30G has not configured the system to send voice data to the other network's ground IMS AGW, it will send a request message (H.248 MOD request) to the IMS AGW30FR requesting configuration related to voice communication control (or modification).

[0140] S288: IMS AGW30FR sets the destination termination point for data transmission with the destination device.

[0141] S289: IMS AGW30FR sends a response message (H.248 MOD response) to P-CSCF30G for the request message received in S287.

[0142] S290:P-CSCF30G sends a message (SIP re-INVITE) to terminal 20A requesting a change in voice call settings, including the setting to send voice media to the ground IMS AGW30FR. For example, the message is written as SIP re-INVITE (SDP offer (c= the originating ground IMS AGW IP address)).

[0143] S291: Terminal 20A sends a response message (SIP 200 OK) to P-CSCF30G for the message received in S290. This message includes the IP address of terminal 20A's endpoint in the negotiation response (SDP answer), and is written as, for example, SIP 200 OK (SDP answer (c= the originating UE IP address)).

[0144] S292:P-CSCF30G sends a response message (SIP 200 OK) to S-CSCF30H. This message includes the IP address of the originating ground IMS AGW30FR termination point used by the receiving side in the negotiated response (SDP answer), and is written as, for example, SIP 200 OK (SDP answer (c= the originating ground IMS AGW IP address used by the terminating side)).

[0145] S293: S-CSCF30H sends a response message (SIP 200 OK) to SAT IMS AS30X for the message received in S292.

[0146] S294: SAT IMS AS30X sends a message (SIP re-INVITE) to S-CSCF30H requesting a change in voice call settings, which includes information (a=ground fallback-requested-to-fixedpart) requesting that voice data be sent to the ground IMS AGW. For example, the message is written as SIP re-INVITE (PSI(satellite constellation id, satellite-id), SDP offer (c=the originating ground IMS AGW IP address, a=ground fallback-requested-to-fixedpart)).

[0147] S295: S-CSCF30H sends the message received in S294 (SIP re-INVITE) to I-CSCF30I.

[0148] S296: I-CSCF30I sends the message received in S295 (SIP re-INVITE) to S-CSCF30H2.

[0149] S297: S-CSCF30H2 sends the message received in S296 (SIP re-INVITE) to SAT IMS AS30X2.

[0150] S298: SAT IMS AS30X2 sends the message received in S297 (SIP re-INVITE) to S-CSCFH2.

[0151] S299: S-CSCF30H2 sends the message received in S298 (SIP re-INVITE) to P-CSCF30G2.

[0152] S300:P-CSCF30G2 sends a message (SIP re-INVITE) to terminal 20B requesting a change in voice call settings. This message includes the IP address of the termination point of the receiving IMS AGW30FR2 and is written, for example, as SIP re-INVITE (SDP offer (c=the terminating ground IMS AGW IP address)).

[0153] S301: Terminal 20B sends a response message (SIP 200 OK) to P-CSCF30G2 for the message received in S300. This message includes information indicating that the connection is via satellite (access-type=3GPP-NR-SAT), MCC, MNC, TAC, and NR cell ID in the PANI, and the negotiated response (SDP answer) includes the IP address of the termination point of the originating terminal 20B. For example, this message is written 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)).

[0154] S302:P-CSCF30G2 sends a message (SIP 200 OK) to S-CSCF30H2 indicating a successful response. This message includes information in the PANI indicating that the connection is via satellite (access-type=3GPP-NR-SAT), MCC, MNC, TAC, and NR cell ID, and the SDP answer includes the IP address of the termination point of the receiving ground IMS AGW30FR2. For example, this message is written 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 ground IMS AGW IP address)).

[0155] S303: S-CSCF30H2 sends the message received by S302 (SIP 200 OK) to SAT IMS AS30X2.

[0156] S304: SAT IMS AS30X2 sends a success response message (SIP 200 OK) to S-CSCF30H2. This message includes the IP address of the termination point of the receiving ground IMS AGW30FR2. For example, the message is written as SIP 200 OK (SDP answer (c= the terminating ground IMS AGW IP address)).

[0157] S305: S-CSCF30H2 sends the message received in S304 (SIP 200 OK) to I-CSCF30I.

[0158] S306: I-CSCF30I sends the message received in S305 (SIP 200 OK) to S-CSCF30H.

[0159] S307: S-CSCF30H sends the message received in S306 (SIP 200 OK) to SAT IMS AS30X.

[0160] S310: The voice call between terminal 20A and terminal 20B continues seamlessly.

[0161] As demonstrated by the above embodiment, in a satellite-based wireless communication system, ground fallback routing via the ground can be performed during satellite switching without changing the existing specifications of P-CSCF.

[0162] (Device configuration) Next, we will describe 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 the functions to perform the embodiments described above. However, the base station 10, network node 30, and terminal 20 may each have only some of the functions in the embodiments.

[0163] <Base station 10 and network node 30> Figure 9 shows an example of the functional configuration of a base station 10 and a network node 30. As shown in Figure 9, 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 9 is merely an example. The functional classifications and names of the functional units can be anything as long as they can perform the operations according to the embodiment of the present invention. The network node 30 may have the same functional configuration as the base station 10. Furthermore, a network node 30 having multiple different functions on the system architecture may be composed of multiple network nodes 30 separated by function.

[0164] The transmitting unit 110 includes the function of generating a signal to be transmitted to the terminal 20 or other network node 30 and transmitting the signal by wire or wireless. The receiving unit 120 includes the function of receiving various signals transmitted from the terminal 20 or other network node 30 and obtaining information from the received signal, for example, higher layer information. A communication unit including the transmitting unit 110 and the receiving unit 120 may be configured.

[0165] The setting unit 130 stores pre-configured setting information and various setting information to be transmitted to the terminal 20 in a storage device, and reads it from the storage device as needed.

[0166] The control unit 140 performs the processes described in the embodiment. The control unit 140 also performs processing related to communication with the terminal 20. The signal transmission function of the control unit 140 may be included in the transmission unit 110, and the signal reception function of the control unit 140 may be included in the reception unit 120.

[0167] <Terminal 20> Figure 10 shows an example of the functional configuration of terminal 20. As shown in Figure 10, 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 Figure 10 is merely an example. The functional classifications and names of the functional units can be anything as long as they can perform the operations according to the embodiment of the present invention. Furthermore, the communication device that becomes the resource holder 20 may have a functional configuration similar to that of terminal 20.

[0168] The transmitting unit 210 creates a transmission signal from the transmission data and transmits the transmission signal wirelessly. The receiving unit 220 wirelessly receives various signals and obtains signals from higher layers from the received physical layer signals. The receiving unit 220 also has the function of receiving control signals or reference signals transmitted from the network node 30. A communication unit including the transmitting unit 210 and the receiving unit 220 may be configured.

[0169] The setting unit 230 stores various setting information received from the network node 30 by the receiving unit 220 in its storage device and reads it from the storage device as needed. The setting unit 230 also stores pre-configured setting information.

[0170] The control unit 240 performs the processing described in the embodiment. The signal transmission function in the control unit 240 may be included in the transmission unit 210, and the signal reception function in the control unit 240 may be included in the reception unit 220.

[0171] (Hardware configuration) The block diagrams (Figures 9 and 10) used in the description of the above embodiments show functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or it may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wired or wireless connections). A functional block may be realized by combining the one or more devices with software.

[0172] Functions include, but are not limited to, judgment, decision, judgment, calculation, calculation, processing, derivation, investigation, exploration, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, assumption, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating (mapping), and assigning. For example, a functional block (configuration part) that enables transmission is called a transmitting unit or transmitter. As mentioned above, the method of implementation is not particularly limited.

[0173] For example, the base station 10, network node 30, terminal 20, etc. in one embodiment of the present disclosure may function as a computer that processes the wireless communication method of the present disclosure. Figure 11 is a diagram showing an example of the hardware configuration of the base station 10 and terminal 20 according to one embodiment of the present disclosure. The network node 30 may have a hardware configuration similar to that of the base station 10. The base station 10 and terminal 20 described above 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.

[0174] In the following explanation, the term "device" can be read as "circuit," "device," "unit," etc. The hardware configuration of the base station 10 and terminal 20 may include one or more of the devices shown in the figure, or it may be configured without some of the devices.

[0175] Each function in the base station 10 and terminal 20 is realized by loading predetermined software (programs) onto hardware such as the processor 1001 and storage device 1002, which allows the processor 1001 to perform calculations, control communication by the communication device 1004, and control at least one of the reading and writing of data in the storage device 1002 and auxiliary storage device 1003.

[0176] The processor 1001 controls the entire computer, for example, by running an operating system. The processor 1001 may consist of a central processing unit (CPU) that includes interfaces with peripheral devices, control devices, arithmetic units, registers, etc. For example, the control unit 140, control unit 240, etc., described above may be implemented by the processor 1001.

[0177] Furthermore, the processor 1001 reads programs (program code), software modules, or data from at least one of the auxiliary storage device 1003 and the communication device 1004 into the storage device 1002, and executes various processes accordingly. The program used is one that causes a computer to execute at least a part of the operations described in the above embodiment. For example, the control unit 140 of the base station 10 shown in Figure 9 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. Also, for example, the control unit 240 of the terminal 20 shown in Figure 10 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. Although the above processes have been described as being executed by one processor 1001, they may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The program may be transmitted from the network via a telecommunications line.

[0178] The storage device 1002 is a computer-readable recording medium and may consist of at least one of the following: ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), etc. The storage device 1002 may also be called a register, cache, main memory, etc. The storage device 1002 can store executable programs (program code), software modules, etc., for implementing a communication method according to one embodiment of this disclosure.

[0179] The auxiliary storage device 1003 is a computer-readable recording medium and may consist of at least one of the following: an optical disc such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disc, a digital multipurpose disc, a Blu-ray® disc), a smart card, flash memory (e.g., a card, a stick, a key drive), a floppy® disk, a magnetic strip, etc. The above-mentioned storage medium may also be a database, server, or other suitable medium that includes at least one of the storage device 1002 and the auxiliary storage device 1003.

[0180] The communication device 1004 is hardware (transceiver / receiver device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as a network device, network controller, network card, communication module, etc. The communication device 1004 may include high-frequency switches, duplexers, filters, frequency synthesizers, etc., to implement at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the transmit / receive antenna, amplifier section, transmit / receive section, transmission path interface, etc., may be implemented by the communication device 1004. The transmit / receive section may be implemented with physically or logically separated transmitting and receiving sections.

[0181] The input device 1005 is an input device that accepts input from an external source (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1006 is an output device that outputs to an external source (e.g., a display, speaker, LED lamp, etc.). The input device 1005 and the output device 1006 may be configured as an integrated unit (e.g., a touch panel).

[0182] 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 different buses may be configured for each device.

[0183] Furthermore, the base station 10 and terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), and an FPGA (Field Programmable Gate Array), and some or all of each functional block may be realized by such hardware. For example, the processor 1001 may be implemented using at least one of these hardware components.

[0184] Figure 12 shows an example of the configuration of vehicle 2001. As shown in Figure 12, vehicle 2001 comprises 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 2021-2029, an information service unit 2012, and a communication module 2013. Each aspect / embodiment described in this disclosure may be applied to a communication device mounted on vehicle 2001, for example, to the communication module 2013.

[0185] The drive unit 2002 consists of, for example, 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, which is operated by the user.

[0186] The electronic control unit 2010 consists of a microprocessor 2031, memory (ROM, RAM) 2032, and communication ports (IO ports) 2033. Signals from various sensors 2021 to 2029 installed in the vehicle 2001 are input to the electronic control unit 2010. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0187] Signals from various sensors 2021-2029 include current signals from current sensor 2021 which senses motor current, front and rear wheel rotation speed signals obtained by rotation speed sensor 2022, front and rear wheel air pressure signals obtained by air pressure sensor 2023, vehicle speed signals obtained by vehicle speed sensor 2024, acceleration signals obtained by acceleration sensor 2025, accelerator pedal depression signals obtained by accelerator pedal sensor 2029, brake pedal depression signals obtained by brake pedal sensor 2026, shift lever operation signals obtained by shift lever sensor 2027, and detection signals obtained by object detection sensor 2028 for detecting obstacles, vehicles, pedestrians, etc.

[0188] The Information Services Unit 2012 consists of various devices for providing (outputting) various types of information such as driving information, traffic information, and entertainment information, including a car navigation system, audio system, speakers, television, and radio, and one or more ECUs that control these devices. The Information Services Unit 2012 uses information acquired from external devices via a communication module 2013, etc., to provide various multimedia information and multimedia services to the occupants of the vehicle 2001. The Information Services Unit 2012 may include input devices that accept input from the outside (e.g., keyboard, mouse, microphone, switch, button, sensor, touch panel, etc.) and output devices that perform output to the outside (e.g., display, speaker, LED lamp, touch panel, etc.).

[0189] The driver assistance system unit 2030 consists of various devices that provide functions to prevent accidents or reduce the driver's workload, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS), 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. The driver assistance system unit 2030 also sends and receives various information via the communication module 2013 to realize driver assistance functions or autonomous driving functions.

[0190] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via its communication port. For example, the communication module 2013 sends and receives data via its communication port 2033 to the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axle 2009, the microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021-29 provided in the vehicle 2001.

[0191] 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 external devices. For example, it can send and receive various types of information to and from external devices 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 or a mobile station.

[0192] The communication module 2013 may transmit at least one of the following to an external device via wireless communication: signals from the various sensors 2021-2028 input to the electronic control unit 2010, information obtained based on said signals, and information based on input from an external source (user) obtained via the information service unit 2012. The electronic control unit 2010, the various sensors 2021-2028, the information service unit 2012, etc., may also be called input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include information based on the above input.

[0193] The communication module 2013 receives various information (traffic information, signal information, inter-vehicle information, etc.) transmitted from an external device and displays it on the information service unit 2012 provided in the vehicle 2001. The information service unit 2012 may also be called an output unit, which outputs information (for example, outputs information to devices such as displays and speakers 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 the external device in memory 2032, which is available to the microprocessor 2031. Based on the information stored in 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 2021-2029, etc., provided in the vehicle 2001.

[0194] <Note> (Additional note 1) A receiving unit that receives information from the first network node about the satellite to which a new terminal will be located, A control unit that determines that it is impossible to set an optimal inter-satellite route based on information about satellites accommodating terminals on other networks and information about satellites newly accommodating terminals on its own network, To the second network node, A first message requesting a change in voice call settings, which includes information requesting the establishment of a ground-based route for a third network node in the local network, A second message requesting a change to the voice call settings includes information requesting the establishment of a ground-based route to the fourth network node of another network, A transmitting unit that sends, A network node that has (Additional note 2) The configuration of the terrestrial IMS (IP Multimedia Subsystem) access gateway has been confirmed. The first network node, A first message requesting a change in voice call settings, which includes information requesting the transmission of voice media to the terrestrial IMS access gateway destined for the second network node of the local network, A second message requesting a change in voice call settings, which includes information requesting the transmission of voice media to a terrestrial IMS access gateway destined for a third network node in another network, A transmitting unit that sends, A network node that has (Additional note 3) A receiving unit receives a first message from a first network node requesting a change in voice call settings, which includes information requesting the establishment of a ground route. A control unit for configuring a terrestrial IMS (IP Multimedia Subsystem) access gateway, A transmitting unit that sends a second message to the terminal requesting a change in voice call settings, including settings for sending voice media to the satellite IMS access gateway, A third message is sent to the second network node, requesting that the packet filter within the terminal, which identifies the voice media and associates it with a QoS (Quality of Service) flow, add the termination point within the terrestrial IMS access gateway as the destination. A network node that has (Additional note 4) A receiving unit receives a first message from a first network node requesting a change in voice call settings, which includes information requesting the transmission of voice media to a terrestrial IMS (IP Multimedia Subsystem) access gateway. If the local network's terrestrial IMS access gateway has not been configured to send voice media to the other network's terrestrial IMS access gateway, a second message requesting an IMS access gateway change, including the said configuration information, is sent. A transmitting unit that sends a third message to the terminal requesting a change in voice call settings, including settings for sending voice media to the terrestrial IMS access gateway, A network node that has (Additional note 5) The first network node receives information about the satellite to which the terminal will be newly accommodated. A step of determining that it is impossible to set an optimal inter-satellite path based on information about satellites accommodating terminals on the other network side and information about satellites newly accommodating terminals on the local network side, To the second network node, A first message requesting a change in voice call settings, which includes information requesting the establishment of a ground-based route for a third network node in the local network, A second message requesting a change to the voice call settings includes information requesting the establishment of a ground-based route to the fourth network node of another network, The steps to send, A communication method performed by network nodes having [a certain feature / ability].

[0195] In any of the provisions of Appendix 1 to Appendix 5, ground fallback routing via the ground can be performed in satellite-based wireless communication systems without changing the existing specifications of P-CSCF during satellite switching.

[0196] (Supplement to the embodiment) While 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, substitutions, etc. Specific numerical examples have been used to facilitate understanding of the invention, but 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, and matters described in two or more items may be combined as needed, and matters described in one item may be applied to matters described in another item (as long as they do not contradict each other). The boundaries of functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries of physical parts. The operation of multiple functional units may be physically performed by one part, or the operation of one functional unit may be physically performed by multiple parts. Regarding the processing procedures described in the embodiments, the order of processing may be changed as long as it does not contradict each other. For the convenience of explaining the processing, the base station 10 and terminal 20 have been described using functional block diagrams, but such devices may be implemented in hardware, software, or a combination thereof. The software operated by the processor of the base station 10 according to an embodiment of the present invention and the software operated by the processor of the terminal 20 according to an embodiment of the present invention may be stored in random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, registers, hard disk (HDD), removable disk, CD-ROM, database, server, or any other suitable storage medium.

[0197] Furthermore, the notification of information is not limited to the embodiments / models described herein and may be carried out by other methods. For example, the notification of information may be carried out by physical layer signaling (e.g., DCI (Downlink Control Information), UCI (Uplink Control Information)), upper layer signaling (e.g., RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling), broadcast information (MIB (Master Information Block), SIB (System Information Block)), other signals, or combinations thereof. Also, RRC signaling may be called RRC messages, and may be, for example, RRC Connection Setup messages, RRC Connection Reconfiguration messages, etc.

[0198] Each aspect / embodiment described in this disclosure includes LTE (Long Term Evolution), LTE-A (LTE-Advanced), 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 (where x is, for example, an integer or decimal)), 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)), and IEEE This may apply to at least one system utilizing 802.20, UWB (Ultra-WideBand), Bluetooth®, or other appropriate systems, and to next-generation systems extended, modified, created, or defined based thereon. It may also apply to a combination of multiple systems (for example, a combination of at least one of LTE and LTE-A with 5G).

[0199] The processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described herein may be reordered, provided they are consistent with each other. For example, the methods described herein present various step elements in an exemplary order and are not limited to that specific order.

[0200] In this specification, specific operations performed by the base station 10 may, in some cases, be performed by its upper node. In a network consisting of one or more network nodes having a base station 10, it is clear that various operations performed for communication with the terminal 20 can be performed by the base station 10 and at least one of the other network nodes (for example, an MME or S-GW, but not limited to these). Although the above example illustrates the case where there is one other network node besides the base station 10, the other network node may be a combination of multiple other network nodes (for example, an MME and an S-GW).

[0201] The information or signals described in this disclosure may be output from a higher layer (or lower layer) to a lower layer (or higher layer). They may also be input and output via multiple network nodes.

[0202] Input and output information may be stored in a specific location (e.g., memory) or managed using a management table. Input and output information may be overwritten, updated, or appended to. Output information may be deleted. Input information may be transmitted to other devices.

[0203] The determination in this disclosure may be made by a value represented by one bit (0 or 1), by a boolean value (true or false), or by a numerical comparison (for example, a comparison with a predetermined value).

[0204] Software should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, and so on, whether they are called software, firmware, middleware, microcode, hardware description languages, or by any other name.

[0205] Furthermore, software, instructions, information, etc., may be transmitted and received via a transmission medium. For example, if software is transmitted from a website, server, or other remote source using at least one of wired technology (such as coaxial cable, fiber optic cable, twisted pair, or digital subscriber line (DSL)) and wireless technology (such as infrared or microwave), then at least one of these wired and wireless technologies is included in the definition of a transmission medium.

[0206] The information, signals, etc. described in this disclosure may be represented using any of the various different techniques. For example, the data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0207] In addition, terms used 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 the channel and symbol may be a signal (signaling). Also, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, cell, frequency carrier, etc.

[0208] The terms “system” and “network” as used in this disclosure are interchangeable.

[0209] Furthermore, the information, parameters, etc., described in this disclosure may be expressed using absolute values, relative values ​​from a given value, or other corresponding information. For example, wireless resources may be indicated by an index.

[0210] The names used for the parameters described above are not restrictive in any way. Furthermore, the formulas and other expressions using these parameters may differ from those expressly disclosed in this disclosure. Various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable name, and therefore, the various names assigned to these various channels and information elements are not restrictive in any way.

[0211] In this disclosure, terms such as "base station (BS)", "wireless base station", "base station equipment", "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. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0212] A base station can house one or more (e.g., three) cells. If a base station houses multiple cells, the entire coverage area of ​​the base station can be divided into several smaller areas, each of which may also be provided with communication services by a base station subsystem (e.g., a Remote Radio Head (RRH)). The terms “cell” or “sector” refer to part or all of the coverage area of ​​at least one of the base station and / or base station subsystems that provide communication services in that coverage.

[0213] In this disclosure, the transmission of information by a base station to a terminal may be interpreted as the base station instructing the terminal to perform information-based control and operation.

[0214] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0215] 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 several other appropriate terms.

[0216] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may also be a device mounted on a mobile body, the mobile body itself, etc. The mobile body refers to a movable object, and its speed of movement is arbitrary. This also includes the case when the mobile body is stationary. The mobile body includes, but is not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcarts, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and items mounted on them. The mobile body may also be a mobile body that moves autonomously based on operation commands. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile body (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). Furthermore, at least one of the base station and the mobile station may include devices that do 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.

[0217] Furthermore, the term "base station" in this disclosure may be interpreted as "user terminal." For example, the various aspects / embodiments of this 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, D2D (Device-to-Device), V2X (Vehicle-to-Everything), etc.). In this case, the terminals 20 may have the functions that the base station 10 has. Also, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, uplink channel, downlink channel, etc., may be interpreted as side channel.

[0218] Similarly, the term "user terminal" in this disclosure may be replaced with "base station." In this case, the base station may be configured to have the same functions as the user terminal described above.

[0219] As used in this disclosure, the terms “determining” and “determining” may encompass a wide variety of actions. “Determining” may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiry (e.g., searching in a table, database, or other data structure), and ascertaining. “Determining” may also include, for example, receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, and accessing (e.g., accessing data in memory). Furthermore, "judgment" and "decision" can include considering something as having been "judged" or "decided" after resolving, selecting, choosing, establishing, comparing, etc. In other words, "judgment" and "decision" can include considering something as having been "judged" or "decided" after some action. Also, "judgment (decision)" can be reinterpreted as "assuming," "expecting," or "considering."

[0220] The terms “connected,” “coupled,” or any variation thereof, mean 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” with each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, “connection” may be reinterpreted as “access.” As used in this disclosure, two elements may be considered to be “connected” or “coupled” with each other using at least one of one or more wires, cables, and printed electrical connections, and, in some non-limiting and non-exclusive examples, electromagnetic energy having wavelengths in the radio frequency domain, microwave domain, and optical (both visible and invisible) domain.

[0221] The reference signal can also be abbreviated as RS (Reference Signal), and may be called a pilot depending on the applicable standard.

[0222] In this disclosure, the phrase "based on" does not mean "based solely on" unless otherwise specified. In other words, the phrase "based on" means both "based solely on" and "based at least on."

[0223] Any reference to elements using the designations “first,” “second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Accordingly, references to the first and second elements do not imply that only two elements may be employed, or that the first element must precede the second element in any way.

[0224] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0225] Where the terms “include,” “including,” and variations thereof are used in this disclosure, these terms are intended to be inclusive, as is the term “comprising.” Furthermore, the term “or” as used in this disclosure is not intended to mean exclusive OR.

[0226] In this disclosure, if articles are added through translation, such as a, an, and the in English, this disclosure may include the fact that the noun following these articles is plural.

[0227] In this 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 "combine" may be interpreted similarly to "different."

[0228] Each aspect / embodiment described herein may be used individually, in combination, or switched between as needed during implementation. Furthermore, notification of specific information (e.g., notification that "X is") is not limited to explicit notification, but may also be implicit (e.g., by not providing such notification).

[0229] Although the present disclosure has been described in detail above, it will be 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 intent and scope of the present disclosure as defined by the claims. Therefore, the descriptions in the present disclosure are illustrative and not intended to be restrictive in any way. [Explanation of Symbols]

[0230] 10 base station 110 Transmitter 120 Receiver 130 Setting section 140 Control Unit 20 devices 210 Transmitter 220 Receiver 230 Setting section 240 Control Unit 30 network nodes 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 Department 2004 Accelerator pedal 2005 Brake pedal 2006 Shift Lever 2007 Front Wheel 2008 Rear wheel 2009 Axle 2010 Electronic Control Unit 2012 Information Services Department 2013 Communication Module 2021 Current Sensor 2022 Rotation speed sensor 2023 Pneumatic Sensor 2024 Vehicle Speed ​​Sensor 2025 Accelerometer 2026 Brake Pedal Sensor 2027 Shift lever sensor 2028 Object Detection Sensor 2029 Accelerator pedal sensor 2030 Driver Support Systems Department 2031 Microprocessor 2032 memory (ROM, RAM) 2033 Communication port (I / O port)

Claims

1. A receiving unit that receives information from the first network node about the satellite to which a new terminal will be located, A control unit that determines that it is impossible to set an optimal inter-satellite route based on information about satellites accommodating terminals on other networks and information about satellites newly accommodating terminals on its own network, To the second network node, A first message requesting a change in voice call settings, which includes information requesting the establishment of a ground-based route to the third network node of the local network, A second message requesting a change to the voice call settings includes information requesting the establishment of a ground-based route to the fourth network node of another network, A transmitting unit that sends, A network node that has

2. The configuration of the terrestrial IMS (IP Multimedia Subsystem) access gateway has been confirmed. To the first network node, A first message requesting a change in voice call settings, which includes information requesting the transmission of voice media to the terrestrial IMS access gateway destined for the second network node of the local network, A second message requesting a change in voice call settings, which includes information requesting the transmission of voice media to a terrestrial IMS access gateway destined for a third network node in another network, A transmitting unit that sends, A network node that has

3. A receiving unit receives a first message from a first network node requesting a change in voice call settings, which includes information requesting the establishment of a ground route. A control unit for configuring a terrestrial IMS (IP Multimedia Subsystem) access gateway, A transmitting unit that sends a second message to the terminal requesting a change in voice call settings, including settings for sending voice media to the satellite IMS access gateway, A third message is sent to the second network node, requesting that the packet filter within the terminal, which identifies the voice media and associates it with a QoS (Quality of Service) flow, add the termination point within the terrestrial IMS access gateway as the destination. A network node that has

4. A receiving unit receives a first message from a first network node requesting a change in voice call settings, which includes information requesting the transmission of voice media to a terrestrial IMS (IP Multimedia Subsystem) access gateway. If the local network's terrestrial IMS access gateway has not been configured to send voice media to the other network's terrestrial IMS access gateway, a second message requesting a change of IMS access gateway, including the said configuration information, is sent. A transmitting unit that sends a third message to the terminal requesting a change in voice call settings, including settings for sending voice media to the terrestrial IMS access gateway, A network node that has

5. The first network node receives information about the satellite to which a new terminal will be accommodated, A step in which it is determined that it is impossible to set an optimal inter-satellite path based on information about satellites accommodating terminals on the other network side and information about satellites newly accommodating terminals on the local network side, To the second network node, A first message requesting a change in voice call settings, which includes information requesting the establishment of a ground-based route to the third network node of the local network, A second message requesting a change to the voice call settings includes information requesting the establishment of a ground-based route to the fourth network node of another network, The steps to send, A communication method performed by network nodes having [a certain feature / ability].

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