Network node and communication method

Abstract

In a satellite-based wireless communication system, when a satellite is changed, messages containing information about the switching of the IMS access gateway are transmitted in the appropriate order. [Solution] The network node includes a control unit that decides to start using a destination IMS (IP Multimedia Subsystem) access gateway, and a transmission unit that transmits a second message which includes first information requesting the first network node to transmit a first message containing information indicating a switch to the destination IMS access gateway to another network, and second information concerning the termination point for other networks at the destination IMS access gateway.

Description

Technical Field

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

Background Art

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

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

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

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

[0006] [Non-Patent Document 1] 3GPP TS 23.501 V18.5.0(2024-06) [Non-Patent Document 2] 3GPP TS 23.228 V18.6.0(2024-06) [Non-Patent Document 3] 3GPP TR23.700-29 V19.0.0(2024-06) [Non-Patent Document 4] 3GPP TS 23.228 V18.7.0(2024-09) [Non-Patent Document 5] 3GPP TS 24.229 V18.6.0(2024-09) [Overview of the project] [Problems that the invention aims to solve]

[0007] 3GPP is considering procedures for satellite changes in satellite constellation communications (for example, procedures for continuing the optimal route on the satellite, or procedures for fallback from satellite to the ground (ground fallback)). Here, a procedure is being considered in which, in order to start using the destination IMS Access Gateway (AGW), the P-CSCF sends a SIP (Session Initiation Protocol) MESSAGE to the IMS AS, the IMS AS first sends a SIP re-INVITE to the other network, and then sends a SIP re-INVITE to its own network terminal.

[0008] However, under the existing specifications, the IMS AS sends a SIP re-INVITE to its own network terminal from the outset.

[0009] The present invention has been made in view of the above points, and aims to transmit messages containing information regarding the switching of IMS access gateways in an appropriate order when a satellite is changed in a satellite-based wireless communication system. [Means for solving the problem]

[0010] According to the disclosed technology, a network node is provided having: a control unit that decides to start using a destination IMS (IP Multimedia Subsystem) access gateway; a transmission unit that transmits a second message that includes first information requesting a first network node to transmit a first message containing information indicating a switch to the destination IMS access gateway to another network; and second information relating to the other network-bound termination point at the destination IMS access gateway. [Effects of the Invention]

[0011] According to the disclosed technology, a satellite-based wireless communication system can transmit messages containing information about the switching of IMS access gateways in the appropriate order when a satellite changes. [Brief explanation of the drawing]

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

Best Mode for Carrying Out the Invention

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

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

[0015] In addition, in the embodiment of the present invention, when a wireless parameter or the like is "configured", it may be that a predetermined value is pre-configured, or it may be that the wireless parameter notified from the network node 30 or the terminal 20 is configured.

[0016] FIG. 1 is a diagram for explaining an example of a communication system. As shown in FIG. 1, the communication system is composed of a UE which is a terminal 20 and a plurality of network nodes 30. Hereinafter, it is assumed that one network node 30 corresponds to each function, but one network node 30 may implement a plurality of functions, or a plurality of network nodes 30 may implement one function. In addition, the "connection" described below may be a logical connection or a physical connection.

[0017] The RAN (Radio Access Network) is a network node 30 having radio access functionality, which may include a base station 10, and is connected to the UE, AMF (Access and Mobility Management Function), and UPF (User plane function). The AMF is a network node 30 having functions such as terminating the RAN interface, terminating the NAS (Non-Access Stratum), registration management, connection management, reachability management, and terminal mobility management. The UPF is a network node 30 interconnected with the DN (Data Network) and having functions related to processing user plane data, such as PDU (Protocol Data Unit) session points to the outside, packet routing and forwarding, and user plane QoS (Quality of Service) handling. The UPF and DN constitute a network slice. In the wireless communication network in the embodiment of the present invention, multiple network slices are constructed.

[0018] AMF is connected to UE, RAN, SMF (Session Management function), NSSF (Network Slice Selection Function), NEF (Network Exposure Function), NRF (Network Repository Function), UDM (Unified Data Management), AUSF (Authentication Server Function), PCF (Policy Control Function), and AF (Application Function). AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are interconnected via interfaces based on their respective services: Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0034] (Examples) This document describes a procedure for transmitting messages containing information about switching IMS access gateways in the appropriate order when a satellite changes in a satellite-based wireless communication system.

[0035] In this embodiment, the header information (Handover-Info header) related to handover in the SIP message used when the VPLMN identifier changes during roaming is enhanced. Figure 4 shows an example of information related to a SIP message in an embodiment of the present invention. As shown in Figure 4, the SIP message includes information indicating the switching of the IMS access gateway (handover-completed with agw change), which is a newly defined value in the information element (info element). As a result, while in the existing specification the IMS AS sends SIP re-INVITE to its own network terminal, in this embodiment the IMS AS can send SIP re-INVITE to another network if the value of the information element (info element) of the SIP re-INVITE includes handover-completed with agw change.

[0036] Furthermore, in this embodiment, a newly defined information element (new agw) is included in the SIP message to describe the information about the termination point of IP packets from other networks secured within the destination IMS AGW (IMS AGW). As a result, if the IMS AS receives a SIP message and the Handover-Info header contains information indicating a switch of the IMS access gateway (handover-completed with agw change), it can generate an updated negotiation offer (SDP offer) based on the session information (SDP (Session Description Protocol) information) stored in its own device, overwriting it with the information about the termination point of the destination IMS AGW, and send a SIP re-INVITE containing the generated negotiation offer (SDP offer) to the other network. In subsequent steps, the IMS AS sends a SIP re-INVITE to its own network terminal.

[0037] The details of the processing in this embodiment will be explained below using a sequence diagram. Requests, responses, and notifications sent and received in the following steps may be called messages (for example, request messages). For details on existing specifications regarding the messages sent and received in this sequence diagram, please refer to Non-Patent Documents 4-5. Figure 5 is a diagram showing an example of a sequence diagram in an embodiment of the present invention. This sequence is the procedure for switching the IMS AGW when changing satellites. Before this sequence, it is assumed that terminal 20 has completed call setup with the receiving terminal in the other network 40 within its own network, which includes P-CSCF30A and IMS AS30B. It is also assumed that IMS AS30B stores the SDP information exchanged and agreed with terminal 20 and the SDP information exchanged and agreed with the other network 40 during call setup. The processing of each step will be explained below.

[0038] S101:P-CSCF30A decides to begin using the destination IMS AGW.

[0039] S102:P-CSCF30A sends a message (SIP MESSAGE) to IMS AS30B that includes first information (handover-completed with agw change) requesting that a SIP re-INVITE be sent to the other network, and second information regarding the termination point for the other network in the destination IMS AGW. Here, the message (SIP MESSAGE) may include the first and second information in the handover-related header information (Handover-Info).

[0040] S103: IMS AS30B sends a message (200 OK) to P-CSCF30A in response to the message (SIP MESSAGE) received in S102.

[0041] S104: IMS AS30B generates updated SDP information by replacing the first connection information for the other network 40 in the SDP information exchanged and agreed upon with the other network 40 during call setup with the second information regarding the termination point for the other network in the destination IMS AGW, which is included in the message received in S102.

[0042] S105: IMS AS30B sends a message (SIP re-INVITE) to another network 40, which includes the SDP information updated in S104 as a negotiation proposal (SDP offer).

[0043] S106: IMS AS30B receives a message (200 OK) from another network 40 in response to the message (SIP re-INVITE) sent in S105.

[0044] S107: IMS AS30B extracts fourth connection information for its own network from the negotiation response (SDP answer) contained in the message (200 OK) received in S105.

[0045] S108: IMS AS30B updates the SDP information exchanged and agreed upon with terminal 20 during call setup by replacing the third connection information for terminal 20 (i.e., actually for the IMS AGW within its own network) with the fourth connection information extracted in S107, thereby generating the SDP information.

[0046] S109: IMS AS30B sends a message (SIP re-INVITE) to terminal 20 to P-CSCF30A, which includes the SDP information updated in S108 as a negotiation proposal (SDP offer).

[0047] S110: P-CSCF30A sets the fourth connection information of the SDP offer at the destination IMS AGW. P-CSCF30A updates the fourth connection information of the SDP offer by replacing it with the fifth connection information for the termination point for the local terminal at the destination IMS AGW, and generates SDP information. P-CSCF30A sends a message (SIP re-INVITE) to terminal 20, which includes the SDP information as the SDP offer.

[0048] S111: Terminal 20 sends a message (200 OK) to P-CSCF30A in response to the message (SIP re-INVITE) received in S110.

[0049] S112:P-CSCF30A sends a message (200 OK) to IMS AS30B in response to the message (SIP re-INVITE) received in S109.

[0050] As demonstrated in the above embodiment, in a satellite-based wireless communication system, when a satellite is changed, messages containing information regarding the switching of the IMS access gateway can be transmitted in the appropriate order.

[0051] (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.

[0052] <Base station 10 and network node 30> Figure 6 shows an example of the functional configuration of a base station 10 and a network node 30. As shown in Figure 6, 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 6 is merely an example. The functional classifications and names of the functional units can be anything as long as they can perform the operations according to the embodiment of the present invention. The network node 30 may have the same functional configuration as the base station 10. Furthermore, a network node 30 having multiple different functions on the system architecture may be composed of multiple network nodes 30 separated by function.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] <Terminal 20> Figure 7 shows an example of the functional configuration of terminal 20. As shown in Figure 7, 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 7 is merely an example. The functional classifications and names of the functional units can be anything as long as they can perform the operations according to the embodiment of the present invention. Furthermore, the communication device that becomes the resource holder 20 may have a functional configuration similar to that of terminal 20.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] (Hardware configuration) The block diagrams (Figures 6 and 7) 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.

[0061] 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.

[0062] 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 8 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.

[0063] In the following explanation, the term "device" can be read as "circuit," "device," "unit," etc. The hardware configuration of the base station 10 and terminal 20 may include one or more of the devices shown in the figure, or it may be configured without some of the devices.

[0064] 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.

[0065] 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.

[0066] 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 6 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 7 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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).

[0071] 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.

[0072] 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.

[0073] Figure 9 shows an example of the configuration of vehicle 2001. As shown in Figure 9, vehicle 2001 comprises a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, front wheels 2007, rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021-2029, an information service unit 2012, and a communication module 2013. Each aspect / embodiment described in this disclosure may be applied to a communication device mounted on vehicle 2001, for example, to the communication module 2013.

[0074] 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.

[0075] 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).

[0076] 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.

[0077] 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.).

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] <Note> (Additional note 1) A control unit that decides to start using the destination IMS (IP Multimedia Subsystem) access gateway, A transmission unit that transmits a second message to a first network node, which includes first information requesting the first network node to transmit a first message containing information indicating a switch to the destination IMS access gateway to another network, and second information relating to the termination point for the other network at the destination IMS access gateway. A network node that has (Additional note 2) The second message includes the first and second information in the header information relating to the handover. The network node described in Appendix 1. (Additional note 3) A receiving unit receives a second message from a first network node, which includes first information requesting the transmission of a first message containing information indicating a switch to a destination IMS access gateway (IP Multimedia Subsystem) to another network, and second information concerning the termination point for the other network at the destination IMS access gateway. A transmitting unit that transmits the first message containing the second information to another network, A network node that has (Additional note 4) The system stores the first session information that was exchanged and agreed upon with other networks during call setup. The system further includes a control unit that generates updated second session information by replacing the first connection information for other networks in the first session information with the second information, The transmitting unit transmits the first message, which includes the second session information as a negotiation proposal, to another network. The network node described in Appendix 3. (Additional note 5) The control unit stores the third session information exchanged and agreed upon with the terminal during call setup. The receiving unit receives a second message from another network in response to the first message. The control unit extracts second connection information for its own network from the negotiation response contained in the second message, The control unit generates updated fourth session information by replacing the third connection information for the terminal in the third session information with the second connection information. The transmitting unit sends a third message to the terminal, which includes the fourth session information as a negotiation proposal. The network node described in Appendix 4. (Additional note 6) The steps include deciding to start using the destination IMS (IP Multimedia Subsystem) access gateway, The steps include sending a second message to a first network node, which includes first information requesting the first network node to send a first message to another network containing information indicating a switch to the destination IMS access gateway, and second information relating to the termination point for the other network at the destination IMS access gateway, A communication method performed by network nodes having [a certain feature / ability].

[0084] In any of the provisions of Appendix 1 to Appendix 6, a satellite-based wireless communication system can transmit messages containing information regarding the switching of the IMS access gateway in an appropriate order when a satellite is changed.

[0085] (Supplement to the embodiment) While embodiments of the present invention have been described above, the disclosed invention is not limited to such embodiments, and those skilled in the art will understand various modifications, alterations, alternatives, substitutions, etc. Specific numerical examples have been used to facilitate understanding of the invention, but unless otherwise specified, these numerical values ​​are merely examples, and any appropriate values ​​may be used. The division of items in the above description is not essential to the present invention, and matters described in two or more items may be combined as needed, and matters described in one item may be applied to matters described in another item (as long as they do not contradict each other). The boundaries of functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries of physical parts. The operation of multiple functional units may be physically performed by one part, or the operation of one functional unit may be physically performed by multiple parts. Regarding the processing procedures described in the embodiments, the order of processing may be changed as long as it does not contradict each other. For the convenience of explaining the processing, the base station 10 and terminal 20 have been described using functional block diagrams, but such devices may be implemented in hardware, software, or a combination thereof. The software operated by the processor of the base station 10 according to an embodiment of the present invention and the software operated by the processor of the terminal 20 according to an embodiment of the present invention may be stored in random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, registers, hard disk (HDD), removable disk, CD-ROM, database, server, or any other suitable storage medium.

[0086] 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.

[0087] 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).

[0088] 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.

[0089] 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).

[0090] 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.

[0091] 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.

[0092] 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).

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] The terms “system” and “network” as used in this disclosure are interchangeable.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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."

[0109] 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.

[0110] The reference signal can also be abbreviated as RS (Reference Signal), and may be called a pilot depending on the applicable standard.

[0111] 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."

[0112] 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.

[0113] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0114] 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.

[0115] 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.

[0116] 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."

[0117] 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).

[0118] 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]

[0119] 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 control unit that decides to start using the destination IMS (IP Multimedia Subsystem) access gateway, A transmission unit transmits a second message to a first network node, which includes first information requesting the first network node to transmit a first message containing information indicating a switch to the destination IMS access gateway to another network, and second information relating to the terminal point for the other network at the destination IMS access gateway. A network node that has

2. The second message includes the first information and the second information in the header information relating to the handover. The network node according to claim 1.

3. A receiving unit receives a second message from a first network node, which includes first information requesting the transmission of a first message containing information indicating a switch to a destination IMS access gateway (IP Multimedia Subsystem) to another network, and second information relating to the termination point for the other network at the destination IMS access gateway. A transmitting unit that transmits the first message containing the second information to another network, A network node that has

4. The system stores the first session information that was exchanged and agreed upon with other networks during call setup. The system further includes a control unit that generates updated second session information by replacing the first connection information for other networks in the first session information with the second information, The transmitting unit transmits the first message, which includes the second session information as a negotiation proposal, to another network. The network node according to claim 3.

5. The control unit stores the third session information exchanged and agreed upon with the terminal during call setup. The receiving unit receives a second message from another network in response to the first message. The control unit extracts second connection information for its own network from the negotiation response included in the second message, The control unit generates updated fourth session information by replacing the third connection information for the terminal in the third session information with the second connection information. The transmitting unit sends a third message to the terminal, which includes the fourth session information as a negotiation proposal. The network node according to claim 4.

6. The steps include deciding to start using the destination IMS (IP Multimedia Subsystem) access gateway, The steps include sending a second message to a first network node, which includes first information requesting the first network node to send a first message to another network containing information indicating a switch to the destination IMS access gateway, and second information relating to the terminal point for the other network at the destination IMS access gateway, A communication method performed by network nodes having [a certain feature / ability].

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