Network node

Abstract

In satellite-based communication systems, it is possible to achieve communication between satellites and ground equipment via an appropriate ground gateway. [Solution] A first network node located on a satellite includes a receiving unit that receives a request message from a second network node located on the satellite requesting monitoring of the availability of a feeder link to a third network node located on the ground, and a transmitting unit that, when the feeder link becomes available, transmits a notification to the second network node indicating that the feeder link is available, including identification information of the third network node.

Description

Technical Field

[0001] The present invention relates to a network node in a communication system using satellites. Background Art

[0002] In 3GPP (3rd Generation Partnership Project) (registered trademark), technical specifications for the integration of a Terrestrial Network (TN) and a Non-Terrestrial Network (NTN) in mobile communication technology are under study. NTN is a communication network that does not rely on terrestrial base stations and utilizes satellites (Geostationary Earth Orbit (GEO) satellites, Low Earth Orbit (LEO) satellites, Medium Earth Orbit (MEO) satellites) and High Altitude Platform Stations (HAPS).

[0003] Here, a satellite (for example, a LEO satellite) orbits the Earth, and the distance between the satellite and a terrestrial gateway (GW) and the available GWs for communication change every few minutes. In order to suppress communication disconnection or transmission / reception delay between the satellite and a terrestrial device, it is necessary to select an appropriate terrestrial GW via which communication between the satellite and the terrestrial device is routed. Prior Art Documents Non-Patent Documents

[0004] Non-Patent Document 1 3GPP TS 23.501 V19.2.1 (2025-01) Non-Patent Document 2 3GPP TS 23.228 V19.2.0 (2024-12) Non-Patent Document 3 3GPP TR23.700-29 V19.0.0 (2024-06) [Overview of the project] [Problems that the invention aims to solve]

[0005] However, in conventional satellite-based communication systems, it has been unclear how to determine the appropriate ground link gateway (GW) through which communication between the satellite and ground equipment takes place. As a result, there is a risk of communication interruptions between the satellite and ground equipment, or increased delays in signaling and data transmitted and received between the satellite and ground equipment. [Means for solving the problem]

[0006] According to this embodiment, a first network node located on a satellite includes a receiving unit that receives a request message from a second network node located on the satellite requesting monitoring of the availability of a feeder link to a third network node located on the ground, and a transmitting unit that, when the feeder link becomes available, transmits a notification to the second network node indicating that the feeder link is available, including identification information of the third network node. [Effects of the Invention]

[0007] According to this embodiment, in a communication system using satellites, communication between satellites and ground equipment via an appropriate ground gateway can be realized. [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 diagram showing an example from NTN (1). [Figure 5] This figure shows an example (2) of NTN. [Figure 6]This figure shows an example (3) of NTN. [Figure 7] This sequence diagram shows an example of the procedure for setting up the feeder link status in the satellite according to this embodiment. [Figure 8] This is a sequence diagram showing an example of the procedure for communication between a terminal and a satellite via a service link in this embodiment. [Figure 9] This is a sequence diagram showing an example of the procedure for communication between a satellite and ground equipment via a feeder link in this embodiment. [Figure 10] This figure shows an example of the functional configuration of a base station and network node in this embodiment. [Figure 11] This figure shows an example of the functional configuration of the terminal in this embodiment. [Figure 12] This figure shows an example of the hardware configuration of the base station, terminal, and network node in this embodiment. [Figure 13] This figure shows an example of the vehicle configuration in this embodiment. [Modes for carrying out the invention]

[0009] This embodiment will be described below with reference to the drawings. Note that the embodiments described below are examples, and this embodiment is not limited to the embodiments described below.

[0010] The communication system of this embodiment operates using existing technology. Existing technology is, for example, wireless communication technology based on communication standards such as the 3GPP standard. Existing technology is, for example, NR (New Radio), but is not limited to existing NR. As used herein, the term "NR" has a broad meaning that includes NR (5G) and later systems (e.g., 6G), unless otherwise specified.

[0011] In the present embodiment, the phrase that a radio parameter or the like is "configured" may mean that a predetermined value is pre-configured in advance, or may mean that a radio parameter notified from a network node or the terminal 20 is configured.

[0012] FIG. 1 is a diagram for explaining an example of a communication system. As shown in FIG. 1, the communication system includes the terminal 20 and a plurality of network nodes. The terminal 20 may also be referred to as UE (User Equipment). Hereinafter, it is assumed that one network node corresponds to one function, but one network node may implement a plurality of functions, or a plurality of network nodes may implement one function. Further, the "connection" described below may be a logical connection or a physical connection.

[0013] RAN (Radio Access Network) is a network node having a radio access function, may include the base station 10, and is connected to UE, AMF (Access and Mobility Management Function) and UPF (User plane function). AMF is a network node having functions such as termination of a RAN interface, termination of NAS (Non-Access Stratum), registration management, connection management, reachability management, and terminal mobility management. UPF is a network node having functions related to user plane data processing such as a PDU (Protocol Data Unit) session point for the outside interconnected with DN (Data Network), packet routing and forwarding, and user plane QoS (Quality of Service) handling. UPF and DN constitute a network slice. In the radio communication network according to the present embodiment, a plurality of 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 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 that has functions including session management, IP (Internet Protocol) address allocation and management for UE, DHCP (Dynamic Host Configuration Protocol) function, ARP (Address Resolution Protocol) proxy, roaming function and other functions. NEF is a network node that has a function of notifying capabilities and events to other NFs (Network Functions). NSSF is a network node that has functions including selection of a network slice to which the UE connects, determination of permitted NSSAI (Network Slice Selection Assistance Information), determination of configured NSSAI, determination of an AMF set to which the UE connects and other functions. PCF is a network node that has a function of performing network policy control. AF is a network node that has a function of controlling an application server. NRF is a network node that has a function of discovering NF instances that provide services. UDM is a network node that manages subscriber data and authentication data. UDM is connected to a UDR (User Data Repository) that stores the data. Further, UDM may include ARPF (Authentication credential Repository and Processing Function) that has a function of repository and processing for authentication credentials and SIDF (Subscription Identifier De-concealing Function) that has a function of de-concealing a subscriber identifier, or may be connectable to these functions.

[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 UE (User Interface) which is terminal 20, and multiple network nodes. Hereafter, one network node will be assigned to each function, however, one network node may implement multiple functions, or multiple network nodes may implement one function. Also, the "connection" described below may be a logical connection or a physical connection.

[0017] The RAN is a network node with wireless access capabilities and is connected to the UE, AMF, and UPF. The AMF is a network node with functions such as RAN interface termination, NAS termination, registration management, connection management, reachability management, and mobility management. The UPF is a network node interconnected with the DN, acting as an external PDU session point, performing packet routing and forwarding, and handling QoS for the user plane. The UPF and DN constitute a network slice. In this embodiment of the wireless communication network, 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 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 with functions such as session management, UE IP address assignment and management, DHCP functionality, ARP proxy, and roaming functionality. NEF is a network node with the function of notifying other NFs of capabilities and events. NSSF is a network node 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 with the function of controlling network policy. AF is a network node with the function of controlling application servers. NRF is a network node 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 in both the originating network and the terminating network. Hereafter, one network node will be assigned to each function, however, one network node may implement multiple functions, or multiple network nodes may implement one function. Furthermore, the "connection" described below may be a logical connection or a physical connection. The network node has, for example, the following functions as described in Non-Patent Document 2.

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

[0023] P-CSCF (Proxy-Call Session Control Function) is a network node that provides proxy functionality between the UE and the IMS network, as well as access control functionality for voice communications.

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

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

[0026] The IMS AS (IP Multimedia Subsystem Application Server) is a network node in the IMS network that has functions such as communicating with the DCSF for event notification, receiving data channel control instructions from the DCSF, and communicating with the MF. The IMS AS also receives registration requests for communication termination points from the DCSF, converts the received registration requests into SIP Registers, and sends them to the S-CSCF (Serving-Call Session Control Function). Furthermore, the IMS AS converts data channel establishment requests received from the DCSF into SIP INVITEs and sends them to the S-CSCF.

[0027] DCSF (Data Channel Signaling Function) is a network node that receives event reports from IMS-AS and has functions such as deciding whether or not to allow the provision of data channel services, managing bootstrap data channels, and HTTP web server functionality.

[0028] A Media Function (MF) is a network node in an IMS network that performs functions such as media resource management and data channel media traffic forwarding. The MF 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 a Data Channel Media Function (DCMF). Furthermore, the MF may also be called a Multimedia Resource Function (MRF).

[0029] DCAS (Data Channel Application Server) is a network node that has functions such as being a communication termination point for media and signaling within the IMS network.

[0030] Figure 4 shows an example configuration (1) of NTN (Non-Terrestrial Network) in this embodiment. NTN is a communication network that uses non-terrestrial equipment such as satellites. NTN provides communication services in areas that cannot be covered by terrestrial networks (Terrestrial Network (TN)) (e.g., terrestrial 5G networks). For example, it can be applied to IoT (Internet of Things), ships, buses, trains, and critical communications. NTN has scalability through efficient multicast or broadcast.

[0031] As shown in Figure 4, satellite 10A can retransmit signals from ground base station 10b to provide service to areas where ground base stations are not located, such as mountainous regions. In the example in Figure 4, base station 10b is located on the ground, but base station 10b may also be located on a satellite.

[0032] A terrestrial network may include one or more base stations 10 and terminals 20. A base station 10 is a communication device that provides one or more cells and communicates wirelessly with the terminals 20. The base station 10 may be located on the ground or on a satellite.

[0033] Terminal 20 is a communication device equipped with wireless communication capabilities, such as a smartphone, mobile phone, tablet, wearable device, or M2M (Machine-to-Machine) communication module. Terminal 20 may also be referred to as UE (User Equipment). Terminal 20 receives control signals or data from base station 10 on the downlink and transmits control signals or data to base station 10 on the uplink.

[0034] Figure 5 shows an example configuration (2) of NTN in this embodiment. The area per cell or beam in NTN is very large compared to a terrestrial network. Satellite 10A and NTN GW 10b are connected via a feeder link. The feeder link is a communication link between the satellite and the ground GW. Satellite 10A and UE 20 are connected via a service link.

[0035] As shown in Figure 5, the difference in delay between the near-side UE 20A and the far-side UE 20B is, for example, 10.3 ms for GEO (Geosynchronous orbit) and 3.2 ms for LEO (Low Earth orbit). The beam size in NTN is, for example, 3,500 km for GEO and 1,000 km for LEO.

[0036] Figure 6 shows an example configuration (3) of the NTN in this embodiment. As shown in Figure 6, the NTN may be realized by a satellite in space or an aircraft in the air. For example, a GEO satellite is a satellite located at an altitude of 35,786 km and has a geostationary orbit. For example, an LEO satellite is a satellite located at an altitude of 500-2,000 km and orbits with a period of 88-127 minutes. For example, a HAPS (High Altitude Platform Station) is an aircraft located at an altitude of 8-50 km and performs circling flight.

[0037] As shown in Figure 6, the GEO satellites, LEO satellites, and HAPS aircraft may be connected to ground base stations (gNBs) via gateways (GWs). The service area may be configured to increase in the order of HAPS, LEO, and GEO.

[0038] In the example shown in Figure 6, the base station is located on the ground, but the base station may also be located on a satellite. In this case, the equipment including the base station located on the satellite (satellite equipment) may be connected to network nodes (e.g., AMF, SMF) (ground equipment) located on the ground via a GW (satellite link GW) within the same satellite and a ground GW (ground link GW).

[0039] For example, NTN may extend the coverage of the 5G network to areas that are not yet served or are already served. For example, using NTN can improve the continuity, availability, and reliability of services in ships, buses, trains, or other critical communications. A special parameter indicating that the network is NTN may be sent to terminal 20. Based on the special parameter received, terminal 20 may determine that the network used for communication is NTN.

[0040] Here, the satellite (for example, an LEO satellite) is moving in Earth's orbit, and the distance (relative position) between the satellite and the ground link GW (ground station) and the available ground link GWs change every few minutes. To suppress communication interruptions or transmission / reception delays between the satellite and ground equipment, it is necessary to select an appropriate ground link GW through which communication between the satellite and ground equipment takes place.

[0041] However, in conventional satellite-based communication systems, it has been unclear how to determine the appropriate ground link gateway (GW) through which communication between the satellite and ground equipment takes place. As a result, there is a risk of communication interruptions between the satellite and ground equipment, or increased delays in signaling and data transmitted and received between the satellite and ground equipment.

[0042] According to this embodiment, in a communication system using satellites, communication between a satellite and ground equipment via an appropriate ground link gateway (GW) can be achieved.

[0043] In this embodiment, the ground link GW is an example of one or more GW devices that have an interface connecting the satellite and the ground network (5GC) and relay communication between ground equipment and the satellite. The ground link GW may also be referred to as GW, NTN GW, feeder link GW, Earth Station, ground station, GW node, or network node. The ground link GW may be implemented by network nodes, and the network nodes may include UE functions.

[0044] In this embodiment, the satellite link GW is an example of one or more GW devices included in a satellite, having an interface for connecting to a ground link GW and an interface for connecting to satellite link GWs of other satellites. For example, the satellite link GW may have at least some of the functions of a gNB (base station) and communicate directly with the ground link GW. The satellite link GW may also be referred to as a GW, Satellite Payload, Satellite Regenerative Payload, or network node.

[0045] In this embodiment, the ground equipment is, for example, a network node in 5GC, and may be an AMF or an SMF.

[0046] (Embodiment) The operational overview of this embodiment will now be described. The satellite-based communication system in this embodiment includes ground equipment (e.g., AMF, SMF), a ground link gateway (GW), and a satellite (e.g., a LEO satellite). The satellite includes a satellite link gateway, a satellite N2 mediation function, and a base station (gNB).

[0047] When a satellite link gateway (GW) connects to a ground link gateway (GW), the satellite link gateway notifies the satellite N2 mediation function within the satellite of the connected ground link gateway. The satellite N2 mediation function transmits signaling and / or data to the connected ground link gateway. The satellite N2 mediation function obtains identification information for the associated ground link gateway from the base station within the satellite for each signaling and / or data.

[0048] Below, an example of the operation of the communication system using satellite communication in this embodiment will be explained with reference to Figure 7-9.

[0049] The communication system using satellite communication in this embodiment includes a ground device 30 (e.g., AMF), a ground link GW, an LEO satellite, and a terminal 20-2.

[0050] The ground link gateway includes a Backhaul (BH) UE 20-1. The BH UE 20-1 may function as a terminal (UE) or as a network having terminal functionality. The ground link gateway may be one or more network nodes including the BH UE 20-1.

[0051] The LEO satellite includes satellite link GW, satellite N2 mediation 50, and gNB 10-2.

[0052] The satellite link gateway establishes a feeder link with the ground link gateway at a predetermined time. The satellite link gateway includes a BH gNB 10-1 and a BH UPF 40-1. The BH gNB 10-1 may function as a base station or as a network node having base station functionality. The BH UPF 40-1 may function as a user plane or as a network node having user plane functionality. The satellite link gateway may consist of one or more network nodes including the BH gNB 10-1 and the BH UPF 40-1.

[0053] The satellite N2 mediation 50 may be a satellite N2 mediation function within an LEO satellite, or it may be a network node having a satellite N2 mediation function. The satellite N2 mediation function has at least the function of temporarily buffering N2 messages.

[0054] gNB 10-2 is a base station located on the LEO satellite that communicates with terminal 20-2, and is an example of satellite equipment.

[0055] In this embodiment, the availability of the feeder link between the LEO satellite (satellite link GW) and the ground link GW is monitored. Figure 7 illustrates the setting procedure for monitoring the feeder link status on the LEO satellite.

[0056] As shown in Figure 7, in step S101, the satellite N2 intermediary 50 included in the LEO satellite sends a message to the BH UPF 40-1 requesting monitoring of the feeder link availability. The message requesting monitoring of the feeder link availability is, for example, a Nupf_EventExposure_Subscribe request. The Nupf_EventExposure_Subscribe request is a message used by the UPF to monitor specific events and receive notifications when such events occur.

[0057] The fields in the Nupf_EventExposure_Subscribe request include CreateEventSubscription, which indicates a request to create an event subscription. CreateEventSubscription is set to subscription, which defines the subscription information. subscription is set to upfEvent, which indicates UPF-related event information, as eventList, which indicates a list of events to be monitored. upfEvent is set to type(FEEDERLINK_AVAILABLE), which indicates an event to monitor whether the feeder link is available.

[0058] In step S102, BH UPF 40-1 notifies satellite N2 mediator 50 of the Nupf_EventExposure_Subscribe Response. The Nupf_EventExposure_Subscribe Response is a message that notifies the satellite mediator 50 that the event subscription has been successfully registered if the request is successful.

[0059] By following the above procedure, the event notification function of the BH UPF 40-1 can be used to receive a notification indicating the change in the availability status of the feeder link when a change occurs in the feeder link's availability status.

[0060] After step S101, the BH UPF 40-1 monitors whether there has been a change in the availability status of the feeder link between the satellite link GW and the ground link GW. The BH UPF 40-1 may monitor not only the availability status of the feeder link, but also the availability status of the BH PDU session or the user plane of the BH PDU session via the feeder link. For example, the BH UPF 40-1 may monitor the availability status of at least one of the feeder link, BH PDU session, or user plane, and when the availability status changes, the BH UPF 40-1 may notify the satellite N2 intermediary 50 of the change in availability status.

[0061] Next, using Figure 8, we will explain the procedure by which terminal 20-2 transmits a message via the service link between terminal 20-2 and the LEO satellite at a predetermined time (time T1).

[0062] As shown in Figure 8, in step S201, terminal 20-2 sends a ULInformationTransfer message to the LEO satellite's gNB 10-2. In this embodiment, the message may be referred to as a packet. The field of ULInformationTransfer is set to dedicatedNAS-Message. dedicatedNAS-Message is set to UL NAS transport. In UL NAS transport, the Payload container type is set to "SMS" and the Payload container is set to "CP-DATA". Although Figure 8 shows an example of SMS transmission, the Payload container type may be set to any type of information such as PDU session management, location information, positioning, IMS signaling, or operator-specific data.

[0063] In step S202, gNB 10-2 sends UplinkNASTransport to satellite N2 mediator 50. The NAS-PDU field in this message contains UL NAS transport and User Location Information. In UL NAS transport, the Payload container type is set to "SMS" and the Payload container is set to "CP-DATA". The User Location Information includes PLMN Identity as TAI (Tracking Area Identity) and TAC (Tracking Area Code).

[0064] The satellite N2 intermediary 50 receives the UplinkNASTransport from the gNB 10-2. In step S203, the satellite N2 intermediary 50 derives at least one of the IDs or IP addresses of the ground link GW used by the country corresponding to the country code (MCC (Mobile Country Code)) contained in the PLMN Identity (PLMN information) contained in the received UplinkNASTransport.

[0065] In step S204, the satellite N2 mediator 50 stores the derived ground link GW information (at least one of the ground link GW ID or IP address) in association with the received message (UplinkNASTransport). For example, the satellite N2 mediator 50 may store the received UplinkNASTransport each time it is received.

[0066] Next, the procedure for communication between the satellite and ground equipment via the feeder link between the ground link GW and the LEO satellite (satellite link GW), which is established at a predetermined time, will be explained using Figure 9.

[0067] In Figure 9, a feeder link is established between the ground link GW and satellite link GW#1 (BH UPF 40-1) at a predetermined time (time T2). In step S301, at time T2, a BH PDU session is established between the ground link GW and satellite link GW#1 (BH UPF 40-1) via the feeder link. Once the BH PDU session is established, data is transferred via the BH user plane. A fixed IP address (for example, the IP address of the ground link GW) may be used for the BH PDU session.

[0068] The satellite link gateway's BH UPF 40-1 monitors the subscribed event (FEEDERLINK_AVAILABLE) after the procedure shown in Figure 7. In step S301, the BH UPF 40-1 detects that the feeder link has been established or that the feeder link has become available. In step S302, the BH UPF 40-1 notifies the satellite N2 mediator 50 of a message indicating a change in the availability status of the feeder link. This message is, for example, a Nupf_EventExposure_Notify request.

[0069] The Nupf_EventExposure_Notify field contains NotificationData. NotificationData is a container that holds notification data and stores multiple event notification items (NotificationItem).

[0070] NotificationItems contain NotificationItems that indicate the individual event information to be notified.

[0071] The NotificationItem includes eventType(FEEDERLINK_AVAILABLE), bhueIpv4Addr, and earthLinkGwId. eventType(FEEDERLINK_AVAILABLE) is the event type indicating that the feeder link has become available. bhueIpv4Addr indicates the IPv4 address of the target BH UE 20-1. bhueIpv4Addr may also be referred to as the IP address of the ground link gateway. The IP address version is not limited to IPv4; it may be IPv6 or any other version. earthLinkGwId indicates the identifier of the corresponding ground link gateway. This allows identification of which ground link gateway the feeder link has been established. The ground link gateway identifier and IP address are examples of ground link gateway identification information.

[0072] In step S303, the satellite N2 intermediary 50 sends a Nupf_EventExposure_Notify response to the BH UPF 40-1 in response to the received Nupf_EventExposure_Notify request. The Nupf_EventExposure_Notify response may include a response status code such as 200 OK (success), 400 Bad Request (request error), or 500 Internal Server Error (internal error), and a transaction identifier corresponding to the relevant Nupf_EventExposure_Notify request.

[0073] In step S304, the satellite N2 mediator 50 identifies a message (Uplink NAS Transport) associated with at least one of the ground link GW IDs or IP addresses stored in step S204 of Figure 8 that matches the ground link GW ID (e.g., earthLinkGwId) or IP address (e.g., bhueIpv4Addr) corresponding to the available feeder link that was notified in step S302.

[0074] In step S305, the satellite N2 mediator 50 sets the IP address of the ground link GW as the destination for the identified message and sends the message to the BH UPF 40-1. This message may include the same fields and settings as the Uplink NAS Transport in step S202 of Figure 8.

[0075] In step S306, BH UPF 40-1 forwards the received message (Uplink NAS Transport) to the ground link GW (BH UE 20-1).

[0076] In step S307, the terrestrial link gateway (BH UE 20-1) removes its own IP address (the IP address of the terrestrial link gateway (BH UE 20-1)) from the destination of the received message (Uplink NAS Transport).

[0077] In step S308, the ground link GW (BH UE 20-1) sends a message (Uplink NAS Transport) to the ground device 30 (e.g., AMF) with its own IP address removed from the destination. This message may include the same fields and settings as the Uplink NAS Transport in step S202 of Figure 8.

[0078] According to the embodiment described above, stable communication can be achieved in a satellite-based communication system via an appropriate ground link gateway (GW). Conventionally, there has been a lack of clarity in selecting an appropriate ground link gateway for communication between the satellite and ground equipment, resulting in communication interruptions and delays. However, in this embodiment, the network node on the satellite dynamically monitors the availability status of the feeder link and selects an appropriate ground link gateway, thereby ensuring the continuity of communication.

[0079] According to the embodiment described above, by configuring the network node on the satellite to send a notification containing identification information (identifier or IP address) of the ground link GW when the feeder link becomes available, it becomes possible to select the appropriate communication path across the entire network. This reduces the risk of communication interruption due to the high-speed movement of the satellite and improves the stability of communication between the satellite and ground equipment.

[0080] The satellite network node in the above-described embodiment has the function of dynamically selecting the optimal feeder link gateway (GW) for connecting to the ground network and determining the appropriate GW based on PLMN information and time information. This enables network load balancing, suppresses variations in communication delay, and improves communication efficiency by eliminating unnecessary routes.

[0081] In the above-described embodiment, the satellite network node has a function to request monitoring of the availability of feeder links and dynamically optimizes the communication path in cooperation with the ground network. As a result, when transferring messages to ground equipment (AMF, SMF, etc.), communication delays are reduced and reliable communication is achieved by routing them through the optimal gateway.

[0082] In the embodiments described above, the operation of the N2 interface between gNB 10-2 and AMF (ground equipment 30) was explained. However, this embodiment may also be applied to the N4 interface between SMF (ground equipment 30) and UPF, and the Iq interface between P-CSCF (ground equipment 30) and IMS AGW. This embodiment may also be applied to user data using the N3 interface between gNB 10-2 and UPF (ground equipment 30), and to user data using the N9 interface between ULCL in the LEO satellite and UPF (ground equipment 30).

[0083] (Device configuration) Next, we will describe an example of the functional configuration of the base station 10, network node, and terminal 20 that perform the processes and operations described above. The base station 10, network node, and terminal 20 include the functions to perform the embodiments described above. However, the base station 10, network node, and terminal 20 may each have only some of the functions in the embodiments.

[0084] In this embodiment, the ground equipment 30, ground link GW (BH UE 20-1), satellite link GW (BH gNB 10-1 and BH UPF 40-1), satellite N2 intermediary 50, and gNB 10-2 are all examples of network nodes.

[0085] <Base stations and network nodes> Figure 10 shows an example of the functional configuration of a base station 10 and a network node. As shown in Figure 10, 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 10 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. Note that the network node may have the same functional configuration as the base station 10. Furthermore, a network node having multiple different functions in the system architecture may be composed of multiple network nodes separated by function.

[0086] The transmitting unit 110 includes the function of generating a signal to be transmitted to the terminal 20 or other network node 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 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.

[0087] 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.

[0088] 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.

[0089] <Terminal 20> Figure 11 shows an example of the functional configuration of terminal 20. As shown in Figure 11, 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 11 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.

[0090] 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 network nodes. A communication unit including the transmitting unit 210 and the receiving unit 220 may be configured.

[0091] The configuration unit 230 stores various configuration information received from network nodes by the receiving unit 220 in its storage device and reads it from the storage device as needed. The configuration unit 230 also stores pre-configured configuration information.

[0092] 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.

[0093] (Hardware configuration) The block diagrams (Figures 10 and 11) 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.

[0094] 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.

[0095] For example, the base station 10, network node, 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 12 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 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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 10 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 11 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. Although the above processes have been described as being executed by one processor 1001, they may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The program may be transmitted from the network via a telecommunications line.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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).

[0104] The processor 1001 and the storage device 1002, among other devices, are 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.

[0105] The base station 10 and terminal 20 may be configured with hardware such as a microprocessor, a digital signal processor (DSP), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or 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.

[0106] Figure 13 shows an example of the configuration of vehicle 2001. As shown in Figure 13, 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.

[0107] 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.

[0108] 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).

[0109] 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.

[0110] 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.).

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] <Note> (Additional note 1) A first network node located on the satellite (for example, a satellite link GW (BH UPF 40-1)), A receiving unit receives a request message from a second network node located on the satellite (e.g., satellite N2 mediator 50) requesting monitoring of the availability of a feeder link to a third network node located on the ground (e.g., ground link GW), A first network node comprising: a transmitting unit that, when the feeder link becomes available, transmits to the second network node a notification indicating that the feeder link is available, including identification information of the third network node.

[0117] (Additional note 2) After sending the notification, the receiving unit receives a message from the second network node destined for the third network node having the available feeder link. The transmitting unit is the first network node described in Appendix 1, which transmits the message to the third network node.

[0118] (Additional note 3) A second network node located on the satellite (for example, satellite N2 intermediary 50), A storage unit that stores in association the message transmitted from a fourth network node (e.g., gNB 10-2) located on the satellite with the first identification information of a third network node (e.g., ground link GW) located on the ground, The system includes a receiving unit that receives a notification from a first network node located on the satellite (e.g., satellite link GW (BH UPF 40-1)) indicating that a feeder link to the third network node is available, The notification includes a second network node having the available feeder link, and the notification includes a second identification information of the third network node.

[0119] (Additional note 4) The second network node according to Appendix 3, comprising a transmitting unit for transmitting the message, which is associated with the first identification information that matches the second identification information contained in the notification, to the third network node.

[0120] (Additional note 5) The second network node described in Appendix 3 sends a request message to the first network node requesting it to monitor the availability of the feeder link to the third network node.

[0121] (Additional note 6) The aforementioned message includes PLMN (Public Land Mobile Network) information, The first identification information is associated with the country code included in the PLMN information, and is the second network node as described in Appendix 3.

[0122] (Additional note 7) A communication method performed by a first network node located on a satellite, The steps include receiving a request message from a second network node located on the satellite requesting monitoring of the availability of a feeder link with a third network node located on the ground, A communication method comprising the step of, when the feeder link becomes available, sending a notification to the second network node indicating that the feeder link is available, including identification information of the third network node.

[0123] Any of the provisions of Appendix 1 to Appendix 7 can enable communication between a satellite and ground equipment via an appropriate ground gateway in a satellite-based communication system.

[0124] (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.

[0125] 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.

[0126] 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).

[0127] 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.

[0128] 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).

[0129] 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.

[0130] 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.

[0131] 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).

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] The terms “system” and “network” as used in this disclosure are interchangeable.

[0137] Furthermore, the information, parameters, etc., described in this disclosure may be expressed using absolute values, relative values ​​from a given value, or other corresponding information. For example, wireless resources may be indicated by an index.

[0138] The names used for the parameters described above are not restrictive in any way. Furthermore, the formulas and other expressions using these parameters may differ from those expressly disclosed in this disclosure. Various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable name, and therefore, the various names assigned to these various channels and information elements are not restrictive in any way.

[0139] In this disclosure, terms such as "base station (BS)", "wireless base station", "base station equipment", "fixed station", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", "access point", "transmission point", "reception point", "transmission / reception point", "cell", "sector", "cell group", "carrier", and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0140] 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.

[0141] 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.

[0142] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0143] 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.

[0144] 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 trademarks), 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.

[0145] 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.

[0146] 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.

[0147] 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."

[0148] 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.

[0149] The reference signal can also be abbreviated as RS (Reference Signal), and may be called a pilot depending on the applicable standard.

[0150] 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."

[0151] 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.

[0152] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0153] 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.

[0154] 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.

[0155] 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."

[0156] 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).

[0157] 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]

[0158] 10 base station 110 Transmitter 120 Receiver 130 Setting section 140 Control Unit 20 devices 210 Transmitter 220 Receiver 230 Setting section 240 Control Unit 30 network nodes 1001 Processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication device 1005 Input device 1006 Output device 2001 Vehicle 2002 Drive Unit 2003 Steering Department 2004 Accelerator pedal 2005 Brake pedal 2006 Shift Lever 2007 Front Wheel 2008 Rear wheel 2009 Axle 2010 Electronic Control Unit 2012 Information Services Department 2013 Communication Module 2021 Current Sensor 2022 Rotation speed sensor 2023 Pneumatic Sensor 2024 Vehicle Speed ​​Sensor 2025 Accelerometer 2026 Brake Pedal Sensor 2027 Shift lever sensor 2028 Object Detection Sensor 2029 Accelerator pedal sensor 2030 Driver Support Systems Department 2031 Microprocessor 2032 memory (ROM, RAM) 2033 Communication port (I / O port)

Claims

1. A first network node located on a satellite, A receiving unit receives a request message from a second network node located on the satellite requesting monitoring of the availability of a feeder link with a third network node located on the ground. A first network node comprising: a transmitting unit that, when the feeder link becomes available, transmits a notification to the second network node indicating that the feeder link is available, including identification information of the third network node.

2. After sending the notification, the receiving unit receives a message from the second network node destined for the third network node having the available feeder link. The first network node according to claim 1, wherein the transmitting unit transmits the message to the third network node.

3. A second network node located on the satellite, A storage unit that stores in association the message transmitted from the fourth network node located on the satellite with the first identification information of the third network node located on the ground, The system includes a receiving unit that receives a notification from a first network node located on the satellite indicating that a feeder link to the third network node is available, The notification includes a second network node having the available feeder link, and the notification includes a second identification information of the third network node.

4. The second network node according to claim 3, further comprising a transmitting unit that transmits to the third network node a message associated with the first identification information that matches the second identification information contained in the notification.

5. The second network node according to claim 3, which sends a request message to the first network node requesting monitoring of the availability of the feeder link with the third network node.

6. The aforementioned message includes PLMN (Public Land Mobile Network) information, The second network node according to claim 3, wherein the first identification information is associated with a country code included in the PLMN information.

Images