Network node and communication method

Abstract

In the call setup operation of a satellite-based wireless communication system, it is possible to appropriately determine whether or not the optimal route between the gateways for sending and receiving calls can be set. [Solution] The transmitting network node 30 includes a transmitting unit that sends a message to the receiving network node 30 for establishing a session between terminals, and a receiving unit that receives a response message to the message from the receiving network node. The message includes information indicating a candidate connection destination and an identifier that requests the receiving network node to perform a connectivity check with the candidate connection destination. The candidate connection destination includes at least one of the transmitting first gateway node deployed on a satellite or the transmitting second gateway node deployed on the ground.

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) Rel.19, when deploying the network functions of 5GC and the IMS components on satellites in the realization of IMS voice terminal-satellite-terminal communication (UE-satellite-UE communication, also referred to as satellite communication or satellite constellation communication), discussions are underway on how to reduce the impact on existing specifications (for example, Non-Patent Document 1).

[0003] Conventionally, in satellite constellation communication, methods using satellite identifiers or satellite constellation identifiers have been studied to determine whether an optimal path between satellites can be set. For example, according to the conventional method, based on the identifiers of two specified satellites, it is determined whether there is a link between the two satellites. Further, if it is determined that there is a link between the two satellites, it is assumed that the link permanently exists.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Non-Patent Document 5

[0005] However, with conventional methods, even if the identifiers of two satellites are identified, the link status between the two satellites may change, potentially resulting in a non-existent link. Therefore, the accuracy of determining whether an optimal path can be set is low, and there is a risk that satellite constellation communication may not be performed properly. [Means for solving the problem]

[0006] In this embodiment, the transmitting first network node includes a transmitting unit that sends a message to the receiving second network node for establishing a session between terminals, and a receiving unit that receives a response message to the message from the second network node, wherein the message includes information indicating a candidate connection destination and an identifier that requests the second network node to perform a connectivity check with the candidate connection destination, and the candidate connection destination includes at least one of the transmitting first gateway node deployed on a satellite or the transmitting second gateway node deployed on the ground. [Effects of the Invention]

[0007] According to this embodiment, in the call setup operation of a satellite-based wireless communication system, it is possible to appropriately determine whether or not the optimal route between the gateways for sending and receiving calls can be set. [Brief explanation of the drawing]

[0008] [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 is a sequence diagram (1) showing an example of the call setup procedure in the satellite-based communication system of this embodiment. [Figure 5] This is a sequence diagram (2) showing an example of the call setup procedure in the satellite-based communication system of this embodiment. [Figure 6] This is a sequence diagram (3) showing an example of the call setup procedure in the satellite-based communication system of this embodiment. [Figure 7] This is a sequence diagram (4) showing an example of the call setup procedure in the satellite-based communication system of this embodiment. [Figure 8] This is a sequence diagram (5) showing an example of the call setup procedure in the satellite-based communication system of this embodiment. [Figure 9] This is a sequence diagram (6) showing an example of the call setup procedure in the satellite-based communication system of this embodiment. [Figure 10] This is a sequence diagram (7) showing an example of the call setup procedure in the satellite-based communication system of this embodiment. [Figure 11] This is a sequence diagram (8) showing an example of the call setup procedure in the satellite-based communication system of this embodiment. [Figure 12] This is a sequence diagram (9) showing an example of the call setup procedure in the satellite-based communication system of this embodiment. [Figure 13] This is a sequence diagram (10) showing an example of the procedure for setting up a call in the satellite-based communication system of this embodiment. [Figure 14] This is a sequence diagram (11) showing an example of the procedure for setting up a call in the satellite-based communication system of this embodiment. [Figure 15] This is a sequence diagram (12) showing an example of the call setup procedure in the satellite-based communication system of this embodiment. [Figure 16] This is a sequence diagram (13) showing an example of the procedure for setting up a call in the satellite-based communication system of this embodiment. [Figure 17] This is a diagram showing an example of the functional configuration of a base station and a network node in this embodiment. [Figure 18] This is a diagram showing an example of the functional configuration of a terminal in this embodiment. [Figure 19] This is a diagram showing an example of the hardware configuration of a base station, a terminal, and a network node in this embodiment. [Figure 20] This is a diagram showing an example of the configuration of vehicle 2001 in this embodiment.

Embodiments for Carrying out the Invention

[0009] Hereinafter, this embodiment 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.

[0010] In the operation of the wireless communication system of this embodiment, existing technologies are appropriately used. The existing technologies are, for example, communication methods based on 3GPP standards such as existing NR (New Radio) (5G) / 5GC (5G Core network). However, the existing technologies are not limited to NR / 5GC, and include LTE, LTE-Advanced, and subsequent methods after NR (5G), or wireless LAN (Local Area Network).

[0011] In this embodiment, when a wireless parameter or the like is "configured", it may mean that a predetermined value is pre-configured, or it may mean that a wireless parameter notified from network node 30 or terminal 20 is configured.

[0012] 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.

[0013] The RAN (Radio Access Network) is a network node 30 having wireless 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 user plane data processing, 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 of this embodiment, multiple network slices are constructed.

[0014] 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.

[0015] SMF is a network node 30 that has functions such as session management, IP (Internet Protocol) address assignment 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 policies. 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.

[0016] 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.

[0017] 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, with 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 of this embodiment, multiple network slices are constructed.

[0018] 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.

[0019] 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 performing network policy control. 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.

[0020] 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.

[0021] 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, but one network node 30 may implement multiple functions, or multiple network nodes 30 may implement one function. Also, the "connection" described below may be a logical connection or a physical connection. A network node 30 may have the following functions, for example.

[0022] The IMS-AGW (Access Gateway) is a network node 30 that has gateway functions between the UE and the IMS network, as well as functions related to voice communication access processing.

[0023] 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.

[0024] S-CSCF (Serving-Call Session Control Function) is a network node 30 that has functions related to session control for the UE.

[0025] The I-CSCF (Interrogate-Call Session Control Function) is a network node 30 that serves as the connection point between networks in an IMS network (for example, between the originating and receiving networks) and has functions such as forwarding received SIP requests to the S-CSCF of its own network.

[0026] 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.

[0027] 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.

[0028] 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). Furthermore, the MF may also be called the Multimedia Resource Function (MRF).

[0029] 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.

[0030] 3GPP Rel.19 discusses how to minimize the impact on existing specifications when deploying 5GC network functions and IMS components on satellites in realizing IMS voice terminal-satellite-terminal communication (also known as satellite communication or satellite constellation communication). 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 dealt with are geostationary Earth Orbit (GEO), low Earth Orbit (LEO), and medium Earth Orbit (MEO). Furthermore, 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.

[0031] Conventionally, in satellite constellation communications, methods using satellite identifiers or satellite constellation identifiers have been considered to determine whether an optimal path between satellites can be established. For example, conventional methods determine whether a link exists between two satellites based on the identifiers of the two identified satellites, and if a link is determined to exist between the two satellites, it is assumed that the link will exist permanently.

[0032] However, with conventional methods, even if the identifiers of the two satellites are identified, the state of the link between the two satellites may change, and as a result, the link may not exist. Therefore, the accuracy of determining whether an optimal path can be set may be low.

[0033] Therefore, a new method for determining whether an optimal route can be established between two satellites could be considered in which the originating P-CSCF (Originating P-CSCF) configures both the originating ground IMS AGW and the satellite IMS AGW, the receiving P-CSCF (Terminating P-CSCF) configures both the receiving ground IMS AGW and the satellite IMS AGW, an Interactive Connectivity Establishment (ICE) is operated between the IMS AGWs, and if a connection is established between the originating satellite IMS AGW and the receiving satellite IMS AGW, it could be determined that an optimal route can be established between the satellites.

[0034] The method for implementing satellite constellation communication using the above-mentioned ICE is not clearly defined. For example, if ICE is implemented according to IETF (Internet Engineering Task Force) RFC 8839, the transmitting P-CSCF will only perform connectivity checks (i.e., connectivity checks in ICE) after receiving the first SDP (Session Description Protocol) answer. As a result, the number of steps in the sequence increases, which may increase the load on the network. Furthermore, TS 23.228, which specifies existing ICE usage methods, shows a framework for terminals to access the IMS network across NAT (Network Address Translator). It is necessary to distinguish between this existing ICE usage method and the method using ICE applied to satellite constellation communication. In addition, the behavior when an optimal path between satellites does not exist (link is broken) during satellite communication is not clearly defined.

[0035] According to this embodiment, in the call setting operation of a satellite-based communication system, it is possible to appropriately determine whether or not the optimal route between satellites can be set. The method in this embodiment uses ICE to determine the possibility of setting the optimal route between satellites in the call setting operation by IMS.

[0036] According to the IMS call setup procedure in the satellite-based communication system of this embodiment, the originating P-CSCF sets the originating ground IMS-AGW and the originating satellite IMS-AGW as candidate destinations for the ICE. The originating P-CSCF sends an SDP offer to the receiving P-CSCF that includes the ice-option value "ice2 earlycheck" and information indicating the candidate destination.

[0037] The receiving P-CSCF sets the receiving ground IMS-AGW as the destination candidate for the transmitting ground IMS-AGW and sets the receiving satellite IMS-AGW as the destination candidate for the transmitting satellite IMS-AGW. The receiving P-CSCF instructs the receiving ground IMS-AGW and the receiving satellite IMS-AGW, respectively, to perform a connectivity check with the transmitting ground IMS-AGW and the transmitting satellite IMS-AGW. Once connectivity between the transmitting satellite IMS-AGW and the receiving satellite IMS-AGW is confirmed, the receiving P-CSCF determines that an optimal inter-satellite route can be established. The transmitting P-CSCF determines that an optimal inter-satellite route can be established if it receives an ice2 earlycheck and an SDP answer containing only one destination candidate.

[0038] In this embodiment, connectivity checks can be performed and the feasibility of setting an optimal route between satellites can be determined based on the newly introduced parameter "ice2 earlycheck" and / or the candidate destination included in the SDP offer. "ice2 earlycheck" is an example of an identifier that requests the receiving P-CSCF to perform a connectivity check with the candidate destination.

[0039] The procedure for setting up a call in the satellite-based communication system of this embodiment will be described below with reference to Figure 4-16. Figure 4-16 is a sequence diagram showing a series of call setting procedures, but the communication method in this embodiment may be performed as a part of the procedure shown in Figure 4-16 or as a combination of any multiple procedures.

[0040] Requests, responses, and notifications sent and received in the following procedures may be referred to as messages. For details regarding existing specifications concerning messages sent and received in this sequence diagram, please refer to Non-Patent Document 2-6, etc.

[0041] In this embodiment, it is assumed that multiple low-Earth orbit (LEO) satellites equipped with base stations, ULCLs (Uplink Classifiers), and UPFs form a satellite constellation using inter-satellite links (ISLs). The ULCL has the function of selectively distributing uplink traffic between N9 interfaces.

[0042] 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 ground-based network nodes such as AMFs and SMFs as equipment for satellite constellation utilization.

[0043] In this embodiment, an IMS application server for satellite use (referred to as SAT IMS AS) is introduced, and three sessions are configured in terminal-to-terminal communication: a session between the originating terminal and the originating network SAT IMS AS, a session between the originating network SAT IMS AS and the receiving network SAT IMS AS, and a session between the receiving network SAT IMS AS and the receiving terminal.

[0044] During the IMS AGW switching procedure when a satellite is changed, SAT IMS AS may perform configuration changes to the IMS AGW of the terminal and the opposing network based on instructions from P-CSCF.

[0045] 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.

[0046] The transmitting network includes base stations 10A, ULCL 30E, local IMS AGW 30FL, local UPF (local, PSA2) 30D2L, AMF 30A, SMF 30B, PCF 30C, P-CSCF 30G, S-CSCF 30H, SAT IMS AS 30X, HSS 30J, remote IMS AGW 30FR, and remote UPF (remote, PSA1) 30D1R. P-CSCF 30G is an example of a transmitting P-CSCF. Local IMS AGW 30FL is an example of a transmitting satellite IMS AGW. Remote IMS AGW 30FR is an example of a transmitting ground IMS AGW.

[0047] The receiving network includes base station 10B, ULCL 30E2, local IMS AGW30FL2, local UPF (local, PSA4)30D5L, AMF30A2, SMF30B2, PCF30C2, P-CSCF30G2, S-CSCF30H2, SAT IMS AS30X2, HSS30J2, remote IMS AGW 30FR2, and remote UPF (Remote, PSA3) 30D4R. P-CSCF 30G2 is an example of a receiving P-CSCF. Local IMS AGW30FL2 is an example of a receiving satellite IMS AGW. Remote IMS AGW 30FR2 is an example of a receiving ground IMS AGW.

[0048] Figure 4 is a sequence diagram showing an example of the operation of a satellite-based communication system in this embodiment.

[0049] In step S1001, terminal 20A sends a SIP INVITE message to P-CSCF 30G. The SIP INVITE message includes PANI (P-Access-Network-Info) and SDP offer.

[0050] PANI (access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID) includes information indicating that terminal 20A is accessing a satellite network and identifying the cell that terminal 20A is accessing. access-type indicates the access network type, and 3GPP-NR-SAT indicates that it is an NR-SAT (Non-Terrestrial Network). utran-cell-id-3gpp indicates the ID of the cell to which the terminal is connected and consists of MCC (Mobile Country Code), MNC (Mobile Network Code), TAC (Tracking Area Code), and NR cell ID.

[0051] The SDP offer (c= the originating UE IP address) includes the IP address of terminal 20A. c= indicates connection information, and the IP address of the originating UE is set there.

[0052] In step S1002, P-CSCF 30G sends an Npcf_PolicyAuthorization_Create request to PCF 30C. This request includes an AppSessionContext.

[0053] AppSessionContext(ascReqData(evSubsc(events(event=ANI_REPORT, notifMethod=ONE_TIME), reqAnis(SATELLITE_INFO)))) is the application session context that requests notification of the ANI-REPORT event. The ANI-REPORT event is an Access Network Information (ANI) reporting event. notifMethod indicates the notification method, and ONE_TIME means a one-time notification. reqAnis indicates the ANI being requested, and SATELLITE_INFO indicates that satellite information is being requested.

[0054] In step S1003, PCF 30C sends an Npcf_PolicyAuthorization_Create response to P-CSCF 30G. This response indicates that the policy authorization request has been accepted.

[0055] In step S1004, PCF 30C sends an Npcf_SMPolicyControl_UpdateNotify request to SMF 30B. This request includes SmPolicyNotification.

[0056] SmPolicyNotification(smPolicyDecision(lastReqRuleData(reqData(SATELLITE_INFO)), policyCtrlReqTriggers(AN_INFO))) is an SM policy notification containing satellite network information. policyCtrlReqTriggers indicates a policy control request trigger, and AN_INFO indicates that access network information is the trigger.

[0057] In step S1005, SMF 30B sends an Npcf_SMPolicyControl_UpdateNotify response to PCF 30C. This response includes UeCampingRep.

[0058] UeCampingRep(satelliteInfo(satellite constellation id, satellite id)) is a UE camping report that includes the satellite constellation ID and satellite ID.

[0059] In step S1006, PCF 30C sends an Npcf_PolicyAuthorization_Notify request to P-CSCF 30G. This request includes an EventsNotification.

[0060] EventsNotification(evNotifs(event=ANI_REPORT), satelliteInfo(satellite constellation id, satellite id)) is an event notification that includes notifications for ANI-REPORT events and satellite information.

[0061] In step S1007, P-CSCF 30G sends an Npcf_PolicyAuthorization_Notify response to PCF 30C. This response indicates that an event notification has been received.

[0062] In step S1008, the P-CSCF 30G decides to use ICE (Interactive Connectivity Establishment) to check connectivity between the originating IMS AGW (Access Gateway) and the incoming IMS AGW on the satellite link. This is done to select the optimal media path.

[0063] In step S1009, P-CSCF 30G sends an H.248 ADD request to IMS AGW 30FR. This message requests IMS AGW 30FR to reserve a connection point. This request includes an ICE host candidate request. H.248 is a standard that defines media gateway control protocols.

[0064] In step S1010, the IMS AGW 30FR reserves the resources of the termination point within its own device for data communication with the incoming side.

[0065] In step S1011, IMS AGW 30FR sets the ICE host candidate to be the same as the termination resource reserved in step S1010. The ICE host candidate is a candidate address that IMS AGW uses to check connectivity using ICE.

[0066] In step S1012, IMS AGW 30FR sends an H.248 ADD response to P-CSCF 30G. This response includes an ICE host candidate (ICE host candidate_MO_ground). ICE host candidate_MO_ground is the ICE host candidate for the Mobile Originating ground station.

[0067] In step S1013, P-CSCF 30G sends an H.248 ADD request to IMS AGW 30FL. This message requests IMS AGW 30FL to reserve a connection point. This request includes an ICE host candidate request.

[0068] In step S1014, the IMS AGW 30FL reserves the resources of the termination point within its own device for data communication with the incoming side.

[0069] In step S1015, IMS AGW 30FL sets the ICE host candidate to be the same as the endpoint resource reserved in step S1014.

[0070] In step S1016, IMS AGW 30FL sends an H.248 ADD response to P-CSCF 30G. This response includes an ICE host candidate (ICE host candidate_MO_satellite), which is the ICE host candidate for the originating satellite station.

[0071] Figure 5 is a sequence diagram showing an example of the operation of a satellite-based communication system in this embodiment.

[0072] In step S1017, P-CSCF 30G transmits two IMS AGW addresses using ICE-related attributes.

[0073] In step S1018, P-CSCF 30G sets a=ice-options:ice2 earlycheck to indicate that the other party can initiate connectivity checks. This is set as an attribute of the SDP offer. The ice2 earlycheck included in the SDP offer is an identifier that causes the receiving P-CSCF 30G2 to perform a connectivity check when it receives an SDP answer.

[0074] In step S1019, P-CSCF 30G sends a SIP INVITE message to S-CSCF 30H. This SIP INVITE message includes a PSI and an SDP offer.

[0075] PSI (satellite constellation ID, satellite-id) includes the satellite constellation ID and the satellite ID.

[0076] The SDP offer (c= the originating ground IMS AGW IP address, a=ice-options:ice2 earlycheck, a=candidate high-priority ICE host candidate_MO_satellite, a=candidate low-priority ICE host candidate_MO_ground) includes the IP address of the ground IMS AGW, ICE options, a high-priority ICE host candidate, and a low-priority ICE host candidate.

[0077] The ICE option is set to "ice2 earlycheck".

[0078] For high-priority ICE host candidates, a termination point (MO_satellite) within the originating satellite IMS AGW (local IMS AGW30FL) is set. For low-priority ICE host candidates, a termination point (MO_ground) within the ground IMS AGW (remote IMS AGW 30FR) is set. "high-priority" and "low-priority" may be expressed as predetermined values. "ICE host candidate_MO_satellite" and "ICE host candidate_MO_ground" may be expressed as IP addresses.

[0079] In step S1020, S-CSCF 30H forwards the SIP INVITE to SAT IMS AS 30X based on the stored filter criteria.

[0080] In step S1021, S-CSCF 30H sends a SIP INVITE message to SAT IMS AS 30X. SAT IMS AS 30X is an IMS Application Server that supports satellite communications.

[0081] In step S1022, the SAT IMS AS 30X acts as a SIP B2B UA (Back-to-Back User Agent). The B2B UA acts as an intermediary between two SIP User Agents, performing SIP message translation and routing.

[0082] In step S1023, SAT IMS AS 30X sends a SIP INVITE message to S-CSCF 30H.

[0083] In step S1024, S-CSCF 30H sends a SIP INVITE message to I-CSCF 30I. I-CSCF 30I acts as the entry point for the IMS network and handles the routing and security of SIP messages.

[0084] In step S1025, I-CSCF 30I sends an Nhss_ImsUECM_Authorize request to HSS (Home Subscriber Server) 30J2. This is a process to discover the S-CSCF, which is the destination for SIP INVITE messages. HSS 30J2 is a server that manages information about subscribers.

[0085] In step S1026, HSS 30J2 sends an Nhss_ImsUECM_Authorize response to I-CSCF 30I.

[0086] Figure 6 is a sequence diagram showing an example of the operation of a satellite-based communication system in this embodiment.

[0087] In step S1027, I-CSCF 30I sends a SIP INVITE message to S-CSCF 30H2. This is the process of forwarding the SIP INVITE message to the receiving S-CSCF.

[0088] In step S1028, S-CSCF 30H2 forwards the SIP INVITE to SAT IMS AS 30X2 based on the stored filter criteria.

[0089] In step S1029, S-CSCF 30H2 sends a SIP INVITE message to SAT IMS AS 30X2.

[0090] In step S1030, SAT IMS AS 30X2 operates as a SIP B2B UA.

[0091] In step S1031, SAT IMS AS 30X2 sends a SIP INVITE message to S-CSCF 30H2.

[0092] In step S1032, S-CSCF 30H2 sends a SIP INVITE message containing an SDP offer to P-CSCF 30G2.

[0093] The SDP offer includes the IP address of the ground IMS AGW, ICE options, high-priority ICE host candidates, and low-priority ICE host candidates. For high-priority ICE host candidates, the termination point (MO_satellite) within the originating satellite IMS AGW (local IMS AGW30FL) is set. For low-priority ICE host candidates, the termination point (MO_ground) within the originating ground IMS AGW (remote IMS AGW 30FR) is set.

[0094] When the receiving P-CSCF 30G2 receives an SDP offer with the ICE option ice2 earlycheck set, it performs connectivity checks with the ICE host candidates (potential destinations) included in the SDP offer. For example, the receiving P-CSCF 30G2 sends a message to the receiving satellite IMS AGW (local IMS AGW30FL2) requesting it to perform connectivity checks with the originating satellite IMS AGW (local IMS AGW30FL), which is set as a high-priority ICE host candidate.

[0095] P-CSCF 30G2 may store information indicating whether a candidate destination for the receiving satellite IMS AGW (local IMS AGW30FL2) can connect to a candidate destination for the transmitting satellite IMS AGW (local IMS AGW30FL), or may access a device that stores such information. P-CSCF 30G2 may assign priority to the corresponding candidate destination for the transmitting satellite IMS AGW (local IMS AGW30FL) for the receiving satellite IMS AGW (local IMS AGW30FL2) that has been determined to be connectable. P-CSCF 30G2 may include the candidate destination for the receiving satellite IMS AGW (local IMS AGW30FL2) to which priority has been assigned in the SDP answer described later.

[0096] In step S1033, P-CSCF 30G2 sends an Npcf_PolicyAuthorization_Create request to PCF 30C2. This request includes the AppSessionContext.

[0097] AppSessionContext(ascReqData(evSubsc(events(event=ANI_REPORT, notifMethod=ONE_TIME), reqAnis(SATELLITE_INFO)))) is the application session context that requests notification of the ANI-REPORT event.

[0098] In step S1034, PCF 30C2 sends an Npcf_PolicyAuthorization_Create response to P-CSCF 30G2.

[0099] In step S1035, PCF 30C2 sends an Npcf_SMPolicyControl_UpdateNotify request to SMF 30B2. This request includes SmPolicyNotification. SmPolicyNotification(smPolicyDecision(lastReqRuleData(reqData(SATELLITE_INFO)), policyCtrlReqTriggers(SATELLITE_INFO))) is an SM policy notification containing satellite network information.

[0100] In step S1036, SMF 30B2 sends an Npcf_SMPolicyControl_UpdateNotify response to PCF 30C2. This response includes a UeCampingRep. UeCampingRep(satelliteInfo(satellite constellation id, satellite id)) is a UE camping report that includes the satellite constellation ID and satellite ID.

[0101] In step S1037, PCF 30C2 sends an Npcf_PolicyAuthorization_Notify request to P-CSCF 30G2. This request includes an EventsNotification. EventsNotification(evNotifs(event=ANI_REPORT), satelliteInfo(satellite constellation id, satellite id)) contains a notification of the ANI-REPORT event and satellite information.

[0102] In step S1038, P-CSCF 30G2 sends an Npcf_PolicyAuthorization_Notify response to PCF 30C2.

[0103] In step S1039, P-CSCF 30G2 recognizes the possibility of optimized routing and decides to use ICE to verify whether optimized routing is actually possible.

[0104] In step S1040, P-CSCF 30G2 recognizes a=ice-options:ice2 earlycheck and recognizes that connectivity check is required.

[0105] In step S1041, the third step of the normal P-CSCF-IMS AGW interaction is performed first.

[0106] In step S1042, P-CSCF 30G2 ignores c=line and uses the candidate line to set the remote address of the IMS AGW. c=line is the connection information of the SDP offer. P-CSCF 30G2 ignores c=line and uses the address included in the candidate line of ICE.

[0107] In step S1043, P-CSCF 30G2 sends an H.248 ADD request to IMS AGW 30FR2. The H.248 ADD request is a message that reserves a connection point for IMS AGW 30FR2 and also requests that the information of the peer network's IMS AGW be set at that connection point. This request includes an ICE host candidate request, a request to set the received ICE candidate, and a request to send a connectivity check. The received ICE candidate is, for example, a low-priority ICE host candidate, which is a termination point (MO_ground) within IMS AGW 30FR (the originating ground IMS AGW).

[0108] Figure 7 is a sequence diagram showing an example of the operation of a satellite-based communication system in this embodiment.

[0109] In step S1044, IMS AGW 30FR2 (receiving-side ground IMS AGW) sets the originating-side termination point in its own device settings and reserves the resources of the termination point within its own device for data communication with the originating-side. The termination point within its own device is, for example, the termination point (MT_ground) within IMS AGW 30FR2 (receiving-side ground IMS AGW).

[0110] In step S1045, IMS AGW 30FR2 (receiving-side ground IMS AGW) sets the ICE host candidate to be the same as the termination point within its own device that was reserved above. That is, IMS AGW 30FR2 (receiving-side ground IMS AGW) is set as the low-priority ICE host candidate on the receiving side.

[0111] In step S1046, IMS AGW 30FR2 sends an H.248 ADD response to P-CSCF 30G2. This response includes the incoming ICE host candidate (ICE host candidate_MT_ground).

[0112] In step S1047, IMS AGW 30FR2 (the receiving ground IMS AGW) sends a Connectivity check. This message confirms connectivity with the other party's (the originating party's) IMS AGW 30FR.

[0113] In step S1048, P-CSCF 30G2 sends an H.248 ADD request to IMS AGW 30FL2. This message reserves a connection point for IMS AGW 30FL2 and also requests that the information of the peer network's IMS AGW be set at that connection point. This request includes an ICE host candidate request, a request to set the received ICE candidate, and a request to send a connectivity check. The received ICE candidate is, for example, a high-priority ICE host candidate, such as a termination point (MO_satellite) within IMS AGW 30FL (the originating satellite IMS AGW).

[0114] In step S1049, IMS AGW 30FL2 (the receiving satellite IMS AGW) sets the originating terminal in its own device settings and reserves the resources of the terminal within its device for data communication with the originating side. The terminal within its device is, for example, the terminal (MT_satellite) within IMS AGW 30FL2 (the receiving satellite IMS AGW).

[0115] In step S1050, IMS AGW 30FL2 (the receiving satellite IMS AGW) sets the ICE host candidate to be the same as the termination point within its own device that was reserved above. That is, IMS AGW 30FL2 (the receiving satellite IMS AGW) is set as the high-priority ICE host candidate on the receiving side.

[0116] In step S1051, IMS AGW 30FL2 sends an H.248 ADD response to P-CSCF 30G2. This response includes the incoming ICE host candidate (ICE host candidate_MT_satellite).

[0117] In step S1052, the IMS AGW 30FL2 sends a connectivity confirmation message. This message confirms connectivity with the other (sender) IMS AGW 30FL.

[0118] In step S1053, IMS AGW 30FR2 (the receiving ground IMS AGW) sends an H.248 NOTIFY request to P-CSCF 30G2. This message notifies P-CSCF 30G2 of the result of the connectivity check performed by ICE. When P-CSCF 30G2 receives this message indicating a successful connectivity check, it may determine that a route can be established between IMS AGW 30FR (the originating ground IMS AGW) and IMS AGW 30FR2 (the receiving ground IMS AGW).

[0119] In step S1054, P-CSCF 30G2 sends an H.248 NOTIFY response to IMS AGW 30FR2. This is a response to the NOTIFY request.

[0120] Figure 8 is a sequence diagram showing an example of the operation of a satellite-based communication system in this embodiment.

[0121] In step S1055, IMS AGW 30FL2 (the receiving satellite IMS AGW) sends an H.248 NOTIFY request message to P-CSCF 30G2. This message notifies P-CSCF 30G2 of the result of the connectivity check performed by ICE. If the message indicates a successful connectivity check, P-CSCF 30G2 may determine that an optimal route can be established between IMS AGW 30FL (the sending satellite IMS AGW) and IMS AGW 30FL2 (the receiving satellite IMS AGW). On the other hand, if the message indicates a failure of the connectivity check, P-CSCF 30G2 may determine that an optimal route cannot be established between IMS AGW 30FL and IMS AGW 30FL2.

[0122] In step S1056, P-CSCF 30G2 sends an H.248 NOTIFY response to IMS AGW 30FL2. This is a response to the NOTIFY request.

[0123] In step S1057, P-CSCF 30G2 recognizes that the initiating and receiving satellite IMS AGWs are interconnected and decides to use optimized routing.

[0124] In step S1058, P-CSCF 30G2 sends an H.248 SUBTRACT request to IMS AGW 30FR2. The H.248 SUBTRACT request is a message requesting IMS AGW 30FR2 to release the connection point.

[0125] In step S1059, IMS AGW 30FR2 deletes the settings.

[0126] In step S1060, IMS AGW 30FR2 sends an H.248 SUBTRACT response to P-CSCF 30G2.

[0127] In step S1061, P-CSCF 30G2 performs the first step of the normal P-CSCF-IMS AGW interaction in subsequent processing.

[0128] In step S1062, P-CSCF 30G2 sends an H.248 ADD request to IMS AGW 30FL2. This message requests IMS AGW 30FL2 to reserve the connection point.

[0129] In step S1063, the IMS AGW 30FL2 reserves the resources of its own termination point for data communication with the incoming device.

[0130] In step S1064, IMS AGW 30FL2 sends an H.248 ADD response to P-CSCF 30G2.

[0131] In step S1065, P-CSCF 30G2 sends a SIP INVITE message to terminal 20B. This SIP INVITE message includes an SDP offer. The SDP offer (c = the terminating satellite IMS AGW IP address) includes the IP address of IMS AGW FL2 (the receiving satellite IMS AGW).

[0132] Figure 9 is a sequence diagram showing an example of the operation of a satellite-based communication system in this embodiment.

[0133] In step S1066, terminal 20B sends a SIP 183 Session Progress message to P-CSCF 30G2. This message includes the PANI and SDP answer.

[0134] PANI (access-type=3GPP-NR-SAT, utran-cell-id-3gpp=MCC+MNC+TAC+NR cell ID) includes information indicating that terminal 20B is accessing the satellite network and the cell's identification information.

[0135] The SDP answer (c = the terminating UE IP address) is the SDP answer that includes the IP address of terminal 20B.

[0136] In step S1067, P-CSCF 30G2 sends an H.248 MOD request to IMS AGW 30FL2. The H.248 MOD request is a message requesting that IMS AGW 30FL2 set the IP address of terminal 20B as the connection point.

[0137] In step S1068, the IMS AGW 30FL2 sets the endpoint of the receiving side (i.e., the IP address of terminal 20B) for data communication with the receiving side.

[0138] In step S1069, IMS AGW 30FL2 sends an H.248 MOD response to P-CSCF 30G2.

[0139] In step S1070, the P-CSCF 30G2 sets up the ULCL (Uplink Classifier) ​​and media QoS flow. The ULCL is a network element for classifying uplink traffic.

[0140] In step S1071, P-CSCF 30G2 sends an Npcf_PolicyAuthorization_Create request to PCF 30C2.

[0141] In step S1072, PCF 30C2 sends an Npcf_PolicyAuthorization_Create response to P-CSCF 30G2.

[0142] In step S1073, PCF 30C2 sends an Npcf_SMPolicyControl_UpdateNotify request to SMF 30B2.

[0143] In step S1074, SMF 30B2 sends an Npcf_SMPolicyControl_UpdateNotify response to PCF 30C2.

[0144] In step S1075, the SMF 30B2 selects the ULCL and L-PSA (Local-PDU Session Anchor) based on the satellite ID.

[0145] Figure 10 is a sequence diagram showing an example of the operation of a satellite-based communication system in this embodiment.

[0146] In step S1076, SMF 30B2 sends a PFCP (Packet Forwarding Control Protocol) Session Establishment request to UPF (User Plane Function) 30D5L. This message requests UPF 30D5L to establish a session. UPF is a network element that handles the transfer of user data.

[0147] In step S1077, UPF 30D5L sends a PFCP Session Establishment response to SMF 30B2. The PFCP Session Establishment response is a message sent in response to a PFCP session establishment request.

[0148] In step S1078, SMF 30B2 sends a PFCP Session Establishment request to ULCL 30E2.

[0149] In step S1079, ULCL 30E2 sends a PFCP Session Establishment response to SMF 30B2.

[0150] In step S1080, SMF 30B2 sends a PFCP Session Modification request to UPF 30D4R. A PFCP Session Modification request is a message sent to modify an existing PFCP session.

[0151] In step S1081, UPF 30D4R sends a PFCP Session Modification response to SMF 30B2.

[0152] In step S1082, SMF 30B2 sends a PFCP Session Modification request to UPF 30D5L.

[0153] In step S1083, UPF 30D5L sends a PFCP Session Modification response to SMF 30B2.

[0154] In step S1084, SMF 30B2 sends a Namf_Communication_N1N2MessageTransfer request to AMF 30A2. This request is a message requesting N1 / N2 message transfer. N1 is the interface between the terminal and the AMF, and N2 is the interface between the gNB and the AMF.

[0155] In step S1085, AMF 30A2 sends a Namf_Communication_N1N2MessageTransfer response to SMF 30B2.

[0156] In step S1086, the AMF 30A2 sends a PDU Session Resource Modify Request to base station 10B.

[0157] In step S1087, base station 10B sends an RRCReconfiguration message to terminal 20B. The RRCReconfiguration message is a message for changing the Radio Resource Control settings.

[0158] In step S1088, terminal 20B sends an RRCReconfigurationComplete message to base station 10B.

[0159] In step S1089, base station 10B sends a PDU Session Resource Modify Response to AMF 30A2.

[0160] In step S1090, AMF 30A2 sends an Nsmf_PDUSession_UpdateSMContext request to SMF 30B2. The Nsmf_PDUSession_UpdateSMContext request is a message sent to request an update to the SM context of the PDU session.

[0161] The Nsmf_PDUSession_UpdateSMContext request includes a PDU Session Resource Modification Response Transfer.

[0162] In step S1091, SMF 30B2 sends an Nsmf_PDUSession_UpdateSMContext response to AMF 30A2.

[0163] In step S1092, terminal 20B sends a ULInformationTransfer message to base station 10B. The ULInformationTransfer message is used by terminal 20 to transmit uplink information to base station 10. The UL Information Transfer message includes a NAS (Non-Access Stratum) message from terminal 20B to AMF 30A2.

[0164] In step S1093, base station 10B encapsulates the NAS message contained in the UL Information Transfer message into an Uplink NAS Transport message and transmits the encapsulated Uplink NAS Transport message to AMF 30A2.

[0165] In step S1094, AMF 30A2 sends an Nsmf_PDUSession_UpdateSMContext request to SMF 30B2. The Nsmf_PDUSession_UpdateSMContext request is a message sent to request an update to the SM context of the PDU session.

[0166] In step S1095, SMF 30B2 sends an Nsmf_PDUSession_UpdateSMContext response to AMF 30A2.

[0167] Figure 11 is a sequence diagram showing an example of the operation of a satellite-based communication system in this embodiment.

[0168] In step S1096, P-CSCF 30G2 sends an Npcf_PolicyAuthorization_Update request to PCF 30C2. This request includes an AppSessionContext. AppSessionContext(ascReqData(evSubsc(events(event=SAT_UP_PATH_CH, notifMethod=EVENT_DETECTION)))) is the application session context that requests notification of the SAT_UP_PATH_CH event. The SAT_UP_PATH_CH event is a satellite path change event.

[0169] In step S1097, PCF 30C2 sends an Npcf_PolicyAuthorization_Update response to P-CSCF 30G2.

[0170] In step S1098, PCF 30C2 sends an Nsmf_EventExposure_Subscribe request to SMF 30B2. This request is a message to subscribe to event notifications.

[0171] In step S1099, SMF 30B2 sends an Nsmf_EventExposure_Subscribe response to PCF 30C2.

[0172] In step S1100, P-CSCF 30G2 sends a SIP 183 Session Progress message to S-CSCF 30H2. The SIP 183 Session Progress message includes the PSI and SDP answer.

[0173] PSI (satellite constellation ID, satellite-id) includes the satellite constellation ID and the satellite ID.

[0174] The SDP answer (c= the terminating satellite IMS AGW IP address, a=ice-options:ice2 earlycheck, a=candidate high-priority ICE host candidate_MT_satellite) includes the IP address of the receiving satellite IMS AGW, the ICE options, and the high-priority ICE host candidate. For the ICE options, ice2 earlycheck is set. The ice2 earlycheck included in the SDP answer may indicate that an optimal route can be established between IMS AGW 30FL (the originating satellite IMS AGW) and IMS AGW 30FL2 (the receiving satellite IMS AGW).

[0175] For a candidate high-priority ICE host, a termination point (MT_satellite) within the receiving satellite IMS AGW (local IMS AGW 30FL2) is configured. MT_satellite may be represented as an IP address.

[0176] The SDP answer may also include potential destinations for the receiving ground IMS AGW as ICE host candidates. The destination candidates added to the SDP answer may be associated with priority.

[0177] In step S1101, S-CSCF 30H2 sends a SIP 183 Session Progress message to SAT IMS AS 30X2.

[0178] In step S1102, SAT IMS AS 30X2 sends a SIP 183 Session Progress message to S-CSCF 30H2.

[0179] In step S1103, S-CSCF 30H2 sends a SIP 183 Session Progress message to I-CSCF 30I.

[0180] Figure 12 is a sequence diagram showing an example of the operation of a satellite-based communication system in this embodiment.

[0181] In step S1104, I-CSCF 30I sends a SIP 183 Session Progress message to S-CSCF 30H.

[0182] In step S1105, S-CSCF 30H sends a SIP 183 Session Progress message to SAT IMS AS 30X.

[0183] In step S1106, SAT IMS AS 30X sends a SIP 183 Session Progress message to S-CSCF 30H.

[0184] In step S1107, S-CSCF 30H sends a SIP 183 Session Progress message to P-CSCF 30G containing the SDP answer. The SDP answer includes the IP address of the receiving satellite IMS AGW, the ICE options, and the high-priority ICE host candidate. For the ICE options, ice2 earlycheck is set. For the high-priority ICE host candidate, the termination point (MT_satellite) within the receiving satellite IMS AGW (local IMS AGW 30FL2) is set. MT_satellite may be shown as an IP address.

[0185] As described above, the SDP answer may also include candidate destinations for the receiving ground IMS AGW as ICE host candidates. The destination candidates added to the SDP answer may be associated with priority.

[0186] In step S1108, the transmitting P-CSCF 30G determines that, when the received SDP answer includes the ICE option "ice2 earlycheck", the receiving P-CSCF 30G2 has already performed a connectivity check and that the transmitting satellite IMS AGW (local IMS AGW 30FL) and the receiving satellite IMS AGW (local IMS AGW 30FL2) are interconnected.

[0187] On the other hand, the transmitting P-CSCF 30G determines that the transmitting satellite IMS AGW and the receiving satellite IMS AGW are not connected to each other if the received SDP answer does not include the ICE option "ice2 earlycheck".

[0188] In other words, the transmitting P-CSCF 30G determines whether an optimal route can be established between the transmitting satellite IMS AGW (local IMS AGW 30FL) and the receiving satellite IMS AGW (local IMS AGW 30FL2) based on the SDP answer, which includes the ICE option "ice2 earlycheck".

[0189] Furthermore, as an example, the feasibility of establishing an optimal route between the transmitting satellite IMS AGW and the receiving satellite IMS AGW may be determined based on whether the SDP answer includes one of the destination candidates in addition to the ICE option "ice2 earlycheck". For example, the transmitting P-CSCF 30G may determine whether an optimal route can be established between the transmitting satellite IMS AGW and the receiving satellite IMS AGW when the SDP answer includes the ICE option "ice2 earlycheck" and one destination candidate (satellite IMS AGW).

[0190] Furthermore, as another example, the transmitting P-CSCF 30G may determine that, in addition to the ICE option "ice2 earlycheck" and one candidate destination (satellite IMS AGW) included in the SDP answer, the SDP offer includes a candidate destination (satellite IMS AGW) having the same priority as that candidate destination (satellite IMS AGW), and that these candidate destinations can communicate with each other.

[0191] In step S1109, P-CSCF 30G sends an H.248 SUBTRACT request to IMS AGW 30FR. This message requests IMS AGW 30FR to release the connection point.

[0192] In step S1110, the IMS AGW 30FR deletes its settings.

[0193] In step S1111, the IMS AGW 30FR sends an H.248 SUBTRACT response to the P-CSCF 30G.

[0194] Figure 13 is a sequence diagram showing an example of the operation of a satellite-based communication system in this embodiment.

[0195] In step S1112, P-CSCF 30G sends an H.248 MOD request to IMS AGW 30FL. This message requests IMS AGW 30FL to update the connection point settings for data communication with the incoming device.

[0196] In step S1113, the IMS AGW 30FL requests that the information obtained from the receiving side be set for data communication with the receiving side.

[0197] In step S1114, the IMS AGW 30FL sends an H.248 MOD response to the P-CSCF 30G.

[0198] In step S1115, P-CSCF 30G sends an H.248 ADD request to IMS AGW 30FL. The H.248 ADD request is a message that requests IMS AGW 30FL to reserve a connection point for terminal 20A and to configure the information for terminal 20A at that connection point.

[0199] In step S1116, the IMS AGW 30FL reserves a resource at the termination point within its own device for data communication with the originating side, and sets the originating side's information at that termination point.

[0200] In step S1117, the IMS AGW 30FL sends an H.248 ADD response to the P-CSCF 30G.

[0201] In step S1118, the P-CSCF 30G sets up the ULCL and media QoS flow.

[0202] In step S1119, P-CSCF 30G sends an Npcf_PolicyAuthorization_Create request to PCF 30C.

[0203] In step S1120, PCF 30C sends an Npcf_PolicyAuthorization_Create response to P-CSCF 30G.

[0204] In step S1121, PCF 30C sends an Npcf_SMPolicyControl_UpdateNotify request to SMF 30B.

[0205] In step S1122, SMF 30B sends an Npcf_SMPolicyControl_UpdateNotify response to PCF 30C.

[0206] Figure 14 is a sequence diagram showing an example of the operation of a satellite-based communication system in this embodiment.

[0207] In step S1123, the SMF 30B selects ULCL and L-PSA based on the satellite ID.

[0208] In step S1124, SMF 30B sends a PFCP Session Establishment request to UPF 30D2L. This request is used to request the establishment of a data communication path with terminal 20.

[0209] A PFCP Session Establishment request includes, for example, data transfer rules.

[0210] In step S1125, UPF 30D2L sends a PFCP Session Establishment response to SMF 30B.

[0211] In step S1126, SMF 30B sends a PFCP Session Establishment request to ULCL 30E.

[0212] In step S1127, ULCL 30E sends a PFCP Session Establishment response to SMF 30B.

[0213] In step S1128, SMF 30B sends a PFCP Session Modification request to UPF 30D1R. This request is a message sent to modify an existing PFCP session.

[0214] In step S1129, UPF 30D1R sends a PFCP Session Modification response to SMF 30B.

[0215] In step S1130, SMF 30B sends a PFCP Session Modification request to UPF 30D2L.

[0216] In step S1131, UPF 30D2L sends a PFCP Session Modification response to SMF 30B.

[0217] Figure 15 is a sequence diagram showing an example of the operation of a satellite-based communication system in this embodiment.

[0218] In step S1132, SMF 30B sends a Namf_Communication_N1N2MessageTransfer request to AMF 30A. This request is a message requesting N1 / N2 message transfer. N1 is the interface between the terminal and the AMF, and N2 is the interface between the gNB and the AMF.

[0219] In step S1133, AMF 30A sends a Namf_Communication_N1N2MessageTransfer response to SMF 30B.

[0220] In step S1134, the AMF 30A sends a PDU Session Resource Modify Request to base station 10A.

[0221] In step S1135, base station 10A sends an RRCReconfiguration message to terminal 20A.

[0222] In step S1136, terminal 20A sends an RRCReconfigurationComplete message to base station 10A.

[0223] In step S1137, base station 10A sends a PDU Session Resource Modify Response to AMF 30A.

[0224] In step S1138, AMF 30A sends an Nsmf_PDUSession_UpdateSMContext request to SMF 30B.

[0225] In step S1139, SMF 30B sends an Nsmf_PDUSession_UpdateSMContext response to AMF 30A.

[0226] Figure 16 is a sequence diagram showing an example of the operation of a satellite-based communication system in this embodiment.

[0227] In step S1140, terminal 20A sends a ULInformationTransfer message to base station 10A.

[0228] In step S1141, base station 10A sends an Uplink NAS Transport message to AMF 30A.

[0229] In step S1142, AMF 30A sends an Nsmf_PDUSession_UpdateSMContext request to SMF 30B.

[0230] In step S1143, SMF 30B sends an Nsmf_PDUSession_UpdateSMContext response to AMF 30A.

[0231] In step S1144, P-CSCF 30G sends an Npcf_PolicyAuthorization_Update request to PCF 30C. This request includes an AppSessionContext. AppSessionContext(ascReqData(evSubsc(events(event=SAT_UP_PATH_CH, notifMethod=EVENT_DETECTION)))) is the application session context that requests notification of the SAT_UP_PATH_CH event.

[0232] In step S1145, PCF 30C sends an Npcf_PolicyAuthorization_Update response to P-CSCF 30G.

[0233] In step S1146, PCF 30C sends an Nsmf_EventExposure_Subscribe request to SMF 30B.

[0234] In step S1147, SMF 30B sends an Nsmf_EventExposure_Subscribe response to PCF 30C.

[0235] In step S1148, P-CSCF 30G sends a SIP 183 Session Progress message to terminal 20A. This message includes an SDP answer. The SDP answer (c = the originating satellite IMS AGW IP address) includes the IP address of the originating satellite IMS AGW.

[0236] From step S1148 onward, the normal operation after the establishment of a call connection by terminal 20A is performed.

[0237] According to the embodiment described above, in the call setting operation of a satellite-based wireless communication system, it is possible to appropriately determine whether or not an optimal path can be set between the originating satellite IMS-GW and the receiving satellite IMS-GW.

[0238] (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.

[0239] <Base stations and network nodes> Figure 17 shows an example of the functional configuration of a base station 10 and a network node 30. As shown in Figure 17, 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 17 is merely an example. The functional classifications and names of the functional units can be anything as long as they can perform the operation according to this embodiment. 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.

[0240] 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.

[0241] 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.

[0242] 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.

[0243] <Terminal> Figure 18 shows an example of the functional configuration of terminal 20. As shown in Figure 18, 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 18 is merely an example. The functional classifications and names of the functional units can be anything as long as they can perform the operation according to this embodiment. In addition, the communication device that becomes the resource holder 20 may have a functional configuration similar to that of terminal 20.

[0244] 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.

[0245] 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.

[0246] 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.

[0247] (Hardware configuration) The block diagrams (Figures 17 and 18) 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.

[0248] 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.

[0249] 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 19 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.

[0250] In the following explanation, the term "device" can be replaced with "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.

[0251] 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.

[0252] 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.

[0253] 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 17 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 18 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. Although the above-described processes have been explained 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.

[0254] 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.

[0255] 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.

[0256] 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.

[0257] 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).

[0258] 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.

[0259] 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.

[0260] Figure 20 shows an example of the configuration of vehicle 2001. As shown in Figure 20, 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 2021-2029, 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.

[0261] 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.

[0262] 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).

[0263] 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.

[0264] 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.).

[0265] 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.

[0266] 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.

[0267] 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.

[0268] 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.

[0269] 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.

[0270] <Note> (Additional note 1) The first network node on the sending side, A transmitting unit that sends a message to the receiving second network node to establish a session between terminals, The system includes a receiving unit that receives a response message to the aforementioned message from the second network node, The message includes information indicating a candidate connection destination and an identifier requesting the second network node to perform a connectivity check with the candidate connection destination. The connection destination candidate is a first network node including at least one of a first gateway node on the satellite on the transmission side or a second gateway node on the ground on the transmission side.

[0271] (Additional item 2) The connection destination candidate includes a high-priority connection destination candidate and a low-priority connection destination candidate having a lower priority than the high-priority connection destination candidate. The high-priority connection destination candidate is the first gateway node. The low-priority connection destination candidate is the second gateway node, the network node according to Additional item 1.

[0272] (Additional item 3) When the response message includes the identifier, the network node according to Additional item 1, comprising a control unit configured to determine that an optimal path between the first gateway node and a third gateway node deployed on the satellite on the receiving side can be set.

[0273] (Additional item 4) When the response message does not include the identifier, the network node according to Additional item 3, comprising a control unit configured to determine that an optimal path between the first gateway node and the third gateway node on the receiving side cannot be set.

[0274] (Additional item 5) When the response message includes information indicating a fourth gateway node on the receiving side as a connection destination candidate and the identifier, and the message includes the first gateway node having the same priority as the fourth gateway node, the network node according to Additional item 1, comprising a control unit configured to determine that the fourth gateway node can communicate with the first gateway node.

[0275] (Additional item 6) A communication method executed by a first network node on the transmission side, The steps include sending a message to the receiving second network node to establish a session between terminals, The process includes receiving a response message to the aforementioned message from the second network node, The message includes information indicating a candidate connection destination and an identifier requesting the second network node to perform a connectivity check with the candidate connection destination. A communication method wherein the candidate connection destination includes at least one of a first gateway node of the transmitting side deployed on a satellite or a second gateway node of the transmitting side deployed on the ground.

[0276] In any of the appendices 1-6, it is possible to appropriately determine whether or not the optimal route between the gateways for sending and receiving calls can be set in a satellite-based wireless communication system during the call setting operation.

[0277] (Supplement to the embodiment) Although this embodiment has 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. 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 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 this embodiment and the software operated by the processor of the terminal 20 according to this embodiment 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.

[0278] 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.

[0279] 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).

[0280] 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.

[0281] 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).

[0282] 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.

[0283] 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.

[0284] 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).

[0285] 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.

[0286] 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.

[0287] 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.

[0288] 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.

[0289] The terms “system” and “network” as used in this disclosure are interchangeable.

[0290] Also, the information, parameters, etc. described in this disclosure may be represented using absolute values, relative values from a predetermined value, or using corresponding other information. For example, the radio resources may be indicated by an index.

[0291] The names used for the above-described parameters are not limiting names in any way. Furthermore, the mathematical formulas, etc. using these parameters may be different from those explicitly disclosed in this disclosure. Since various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable names, the various names assigned to these various channels and information elements are not limiting names in any way.

[0292] In this disclosure, terms such as "base station (BS: Base Station)", "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", "component carrier", etc. may be used interchangeably. The base station may also be called by terms such as macro cell, small cell, femto cell, pico cell, etc.

[0293] 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.

[0294] 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 or operation.

[0295] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0296] 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.

[0297] 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.

[0298] 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.

[0299] 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.

[0300] 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."

[0301] 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.

[0302] The reference signal can also be abbreviated as RS (Reference Signal), and may be called a pilot depending on the applicable standard.

[0303] 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."

[0304] 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.

[0305] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0306] 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.

[0307] 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.

[0308] 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."

[0309] 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).

[0310] 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]

[0311] 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. The first network node on the sending side, A transmitting unit that sends a message to the receiving second network node to establish a session between terminals, The system includes a receiving unit that receives a response message to the aforementioned message from the second network node, The message includes information indicating a candidate connection destination and an identifier requesting the second network node to perform a connectivity check with the candidate connection destination. The aforementioned candidate connection destination is a first network node that includes at least one of the following: a first gateway node of the transmitting side deployed on a satellite, or a second gateway node of the transmitting side deployed on the ground.

2. The aforementioned candidate destinations include high-priority candidate destinations and low-priority candidate destinations having a lower priority than the high-priority candidate destinations. The aforementioned high-priority connection destination candidate is the first gateway node, The network node according to claim 1, wherein the low-priority connection destination candidate is the second gateway node.

3. The network node according to claim 1, further comprising a control unit that determines that an optimal route can be established between the first gateway node and a third gateway node deployed on the receiving satellite when the response message includes the identifier.

4. The network node according to claim 3, further comprising a control unit that determines that an optimal route between the first gateway node and the receiving third gateway node is not configurable when the response message does not contain the identifier.

5. The network node according to claim 1, further comprising a control unit which determines that the fourth gateway node can communicate with the first gateway node when the response message includes information indicating a fourth gateway node on the receiving side as a candidate destination and the identifier, and the message includes the first gateway node having the same priority as the fourth gateway node.

6. A communication method performed by the first network node on the initiating side, The steps include sending a message to the receiving second network node to establish a session between terminals, The process includes receiving a response message to the aforementioned message from the second network node, The message includes information indicating a candidate connection destination and an identifier requesting the second network node to perform a connectivity check with the candidate connection destination. A communication method wherein the candidate connection destination includes at least one of a first gateway node of the transmitting side deployed on a satellite or a second gateway node of the transmitting side deployed on the ground.

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