Network node, terminal, and communication method

Abstract

This network node has: a transmission unit that transmits, to a first network node, a first message requesting registration of a terminal in a first communication system that is a communication system including an own device; and a reception unit that receives, from the first network node, a second message including an identifier for a second network node in a second communication system and information that indicates acceptance of the registration. The transmission unit transmits, to the second network node, a third message requesting configuration that relates to cooperation and including information that indicates that the terminal is located in the first communication system. The reception unit receives, from the second network node, a fourth message indicating acceptance of the cooperation.

Description

Network node, terminal, and communication method

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

[0002] 3GPP (registered trademark) (3rd Generation Partnership Project) is currently studying a wireless communication system called 5G or NR (New Radio) (hereinafter, the wireless communication system will be referred to as "5G" or "NR") in order to achieve a larger system capacity, a higher data transmission speed, and a lower latency in wireless sections. Various wireless technologies are being studied for 5G to meet the requirements of achieving a throughput of 10 Gbps or more while keeping latency in wireless sections to 1 ms or less.

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

[0004] 3GPP TS 23.501 V18.4.0 (2023-12) 3GPP TS 23.502 V18.4.0 (2023-12) 3GPP TS 29.503 V18.4.0 (2023-12) 3GPP TS 38.413 V18.0.0 (2023-12) 3GPP TS 24.501 V18.5.0 (2023-12)

[0005] In 5GS, it is possible to fall back from 5GS to EPS (EPS FB (Fall Back)) in case only EPS supports voice call services.

[0006] However, EPS FB uses special network nodes called combo nodes, which can be inconvenient when migrating to new generation systems.

[0007] The present invention has been made in view of the above points, and has an object to enable system fallback in a wireless communication system without using a special network node.

[0008] According to the disclosed technology, a network node is provided which has a transmitter that transmits to a first network node a first message requesting registration of a terminal in a first communication system, which is a communication system including the device itself, and a receiver that receives from the first network node a second message including an identifier of a second network node in a second communication system and information indicating acceptance of the registration, wherein the transmitter transmits to the second network node a third message requesting configuration related to cooperation, which includes information indicating that the terminal is present in the first communication system, and the receiver receives from the second network node a fourth message indicating acceptance of the cooperation.

[0009] According to the disclosed technology, it is possible to enable system fallback in a wireless communication system without using a special network node.

[0010] FIG. 1 is a diagram for explaining an example of a communication system. FIG. 1 is a diagram for explaining an example of a communication system in a roaming environment. FIG. 2 is a diagram showing an example of a first sequence diagram in an embodiment of the present invention. FIG. 3 is a diagram showing an example of a second sequence diagram in an embodiment of the present invention. FIG. 4 is a diagram showing an example of a third sequence diagram in an embodiment of the present invention. FIG. 5 is a diagram showing an example of a fifth sequence diagram in an embodiment of the present invention. FIG. 6 is a diagram showing an example of the functional configuration of a base station 10 and a network node 30 in an embodiment of the present invention. FIG. 7 is a diagram showing an example of the functional configuration of a terminal 20 in an embodiment of the present invention. FIG. 8 is a diagram showing an example of the hardware configuration of a base station 10, a terminal 20, and a network node 30 in an embodiment of the present invention. FIG. 9 is a diagram showing an example of the configuration of a vehicle 2001 in an embodiment of the present invention.

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below is an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

[0012] In the operation of the wireless communication system according to the embodiment of the present invention, existing technology is used as appropriate. However, the existing technology is, for example, the existing LTE, but is not limited to the existing LTE. Furthermore, the term "LTE" used in this specification has a broad meaning including LTE-Advanced, and systems subsequent to LTE-Advanced (e.g., NR), or wireless LAN (Local Area Network), unless otherwise specified.

[0013] Furthermore, in the embodiments of the present invention, "configuring" radio parameters and the like may mean that predetermined values ​​are pre-configured, or that radio parameters notified from the network node 30 or the terminal 20 are set.

[0014] Fig. 1 is a diagram illustrating an example of a communication system. As shown in Fig. 1, the communication system is composed of a UE, which is a terminal 20, and multiple network nodes 30. Hereinafter, it is assumed that one network node 30 corresponds to each function, but multiple functions may be realized by one network node 30, or multiple network nodes 30 may realize one function. Furthermore, the "connection" described below may be a logical connection or a physical connection.

[0015] The RAN (Radio Access Network) is a network node 30 having a radio access function, which may include a base station 10, and is connected to a UE, an AMF (Access and Mobility Management Function), and a UPF (User Plane Function). The AMF is a network node 30 having functions such as terminating the RAN interface, terminating the NAS (Non-Access Stratum), registering management, connecting management, reachability management, and terminal mobility management. The UPF is a network node 30 having functions related to processing user plane data, such as a PDU (Protocol Data Unit) session point to the outside that interconnects with the DN (Data Network), packet routing and forwarding, and user plane Quality of Service (QoS) handling. The UPF and the DN constitute a network slice. In the wireless communication network according to the embodiment of the present invention, multiple network slices are constructed.

[0016] The AMF is connected to the UE, RAN, SMF (Session Management function), NSSF (Network Slice Selection Function), NEF (Network Exposure Function), NRF (Network Repository Function), UDM (Unified Data Management), AUSF (Authentication Server Function), PCF (Policy Control Function), and AF (Application Function). The AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are mutually connected via interfaces based on their respective services, Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

[0017] The SMF is a network node 30 having functions such as session management, UE IP (Internet Protocol) address allocation and management, DHCP (Dynamic Host Configuration Protocol) function, ARP (Address Resolution Protocol) proxy, and roaming function. The NEF is a network node 30 having a function of notifying other NFs (Network Functions) of capabilities and events. The NSSF is a network node 30 having functions such as selecting a network slice to which a UE connects, determining an allowed NSSAI (Network Slice Selection Assistance Information), determining an NSSAI to be set, and determining an AMF set to which a UE connects. The PCF is a network node 30 having a function of controlling network policies. The AF is a network node 30 having a function of controlling application servers. The NRF is a network node 30 having a function of discovering NF instances that provide services. The UDM is a network node 30 that manages subscriber data and authentication data. The UDM is connected to a UDR (User Data Repository) that stores the data.

[0018] Fig. 2 is a diagram illustrating an example of a communication system in a roaming environment. As shown in Fig. 2, the network is composed of a UE, which is a terminal 20, and multiple network nodes 30. Hereinafter, it is assumed that one network node 30 corresponds to each function, but multiple functions may be realized by one network node 30, or multiple network nodes 30 may realize one function. Furthermore, the "connection" described below may be a logical connection or a physical connection.

[0019] The RAN is a network node 30 having a radio access function, and is connected to the UE, the AMF, and the UPF. The AMF is a network node 30 having functions such as RAN interface termination, NAS termination, registration management, connection management, reachability management, and mobility management. The UPF is a network node 30 having functions such as a PDU session point to the outside that interconnects with the DN, packet routing and forwarding, and user plane QoS handling. The UPF and the DN constitute a network slice. In the wireless communication network according to the embodiment of the present invention, multiple network slices are constructed.

[0020] The AMF is connected to the UE, RAN, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, AF, and SEPP (Security Edge Protection Proxy). The AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are interconnected via respective service-based interfaces, Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

[0021] The SMF is a network node 30 having functions such as session management, UE IP address allocation and management, DHCP function, ARP proxy, and roaming function. The NEF is a network node 30 having a function of notifying other NFs of capabilities and events. The NSSF is a network node 30 having functions such as selecting a network slice to which a UE connects, determining an allowed NSSAI, determining a configured NSSAI, and determining an AMF set to which a UE connects. The PCF is a network node 30 having a function of controlling network policies. The AF is a network node 30 having a function of controlling application servers. The NRF is a network node 30 having a function of discovering NF instances that provide services. The SEPP is a non-transparent proxy that filters control plane messages between PLMNs (Public Land Mobile Networks). The vSEPP shown in FIG. 2 is a SEPP in the visited network, and the hSEPP is a SEPP in the home network.

[0022] As shown in Figure 2, a UE is in a roaming environment connected to a RAN and an AMF in a Visited PLMN (VPLMN). The VPLMN and a Home PLMN (HPLMN) are connected via a vSEPP and an hSEPP. The UE can communicate with a UDM in the HPLMN via the AMF in the VPLMN, for example.

[0023] In addition, 5GS allows for fallback from 5GS to EPS (EPS FB (Fall Back)) in case only EPS supports voice call services. EPS FB uses a combo node called SMF + PGW (Packet Data Network Gateway)-C (Control plane) and a UPF shared by EPS and 5GS, which can cause inconvenience when migrating to a new generation system.

[0024] (Example) A procedure for enabling system fallback in a wireless communication system without using a special network node is described. In this example, a fallback from a next-generation system, 6GS (6GS network), to 5GS (5GS network) is assumed. Here, a base station 10A, an AMF 30A, an SMF 30B, and a UPF 30C are deployed in the 5GS system, and a 6G base station 10B, a 6GAMF 30D, a 6GSMF 30E, and a 6GUPF 30F are deployed in the 6GS system. Furthermore, in this example, the following conditions are assumed to be met: When switching between 5GS and 6GS, data discarding is permitted, or data is protected in the application layer so that it is not discarded. A (5G / 6G) UDM 30G, which is a UDM shared by both the 5GS and 6GS systems, is deployed. A terminal 20 is capable of simultaneous transmission and reception (1Tx / 1Rx) in only one of the 5GS and 6GS systems. That is, the terminal 20 cannot simultaneously transmit and receive (2Tx / 2Rx) in the 5GS and 6GS systems. The terminal 20 can be registered in both the 5GS and 6GS systems (dual registration) using a single subscriber information. The AMF 30A and the 6GAMF 30D are assumed to be able to communicate.

[0025] In the above conditions, the following process is performed to enable system fallback without using special network nodes.

[0026] When the UDM30G receives a registration request from the 6GAMF30D after receiving a terminal registration request from the AMF30A, the UDM30G notifies the 6GAMF30D of the destination of the AMF30A.

[0027] 6GAMF30D establishes cooperation with AMF30A.

[0028] AMF30A and 6GAMF30D perform processing related to information indicating whether or not the device is in a 6GS area (6G in-area flag) and information indicating whether or not an incoming call is received in 5GS (5G voice incoming call flag).

[0029] When a voice call comes in via 5GS while terminal 20 is in the 6GS area, AMF30A directly (without going through UDM30G) calls terminal 20 via 6GAMF30D and instructs terminal 20 to send a service request via 5GS.

[0030] The terminal 20 performs periodic registration using either the AMF 30A or the 6GAMF 30D.

[0031] The AMF 30A and the 6GAMF 30D work together to initialize the mobility reachability timer, which is a timer for network nodes involved in periodic registration.

[0032] The following describes the details of the process using a sequence diagram. The requests, responses, notifications, etc. sent and received in the procedures shown below may be called messages (e.g., request messages). Non-Patent Document 2 can be referenced for details of the registration procedure and PDU session establishment procedure in existing specifications related to the messages sent and received in this sequence diagram.

[0033] 3 is a diagram showing an example of a first sequence diagram according to an embodiment of the present invention. The processing of each step in FIG. 3 will now be described.

[0034] In steps S101 to S109, the registration procedure for the terminal 20 to the 5GS is executed.

[0035] S101: The terminal 20 sends a request message (Registration request) to the base station 10A requesting registration of the terminal 20 to 5GS.

[0036] S102: The base station 10A sends a request message (Registration request) to the AMF 30A requesting registration of the terminal 20 to 5GS.

[0037] S103: AMF 30A assumes that, from the UDM perspective, there is a policy that allows dual registration operation in two systems, 5GS and 6GS.

[0038] S104: The AMF 30A transmits to the UDM 30G a request message (Nudm_UECM_Registration request) requesting registration of the terminal 20 in 5GS. This request message is expressed, for example, as Nudm_UECM_Registration request (Amf3GppAccessRegistration(5g6gDrFlag=1)). The Amf3GppAccessRegistration is a data type including information related to the terminal 20 to be registered via 3GPP access (see section 6.2.6.2.2 of Non-Patent Document 3). This data type includes newly defined information (5g6gDrFlag=1) indicating an instruction to allow dual registration in two communication systems, 5GS and 6GS.

[0039] S105: UDM30G registers terminal 20 with 5GS by associating and storing the subscriber identifier (SUPI) of the terminal 20 to be registered, which is included in the request message received in S104, with information regarding AMF30A that controls terminal 20.

[0040] S106: The UDM 30G transmits a response message (Nudm_UECM_Registration response) to the request message received in S104 to the AMF 30A. The request message includes information about the terminal 20 registered in S105, and is expressed as, for example, Nudm_UECM_Registration response (Amf3GppAccessRegistration(5g6gDrFlag=1)).

[0041] S107: The AMF 30A stores the information associated with its own device and registered in the UDM 30G in S105.

[0042] S108: The AMF 30A sends a response message (Registration Acceptance) to the base station 10A in response to the request message received in S102.

[0043] S109: The base station 10A transmits to the terminal 20 a response message (Registration Acceptance) in response to the request message received in S101.

[0044] In steps S111 to S114, a procedure for establishing a PDU session is executed between the terminal 20 and the 5GS.

[0045] S111: An IMS PDU session is established between the terminal 20 and the 5GS.

[0046] S112: A PDU session for data communication is established between the terminal 20 and the 5GS.

[0047] S113: The UPF 30C releases the connection with the base station 10A for the IMS PDU session, and makes it possible to buffer DL user data.

[0048] S114: Communication is performed between the terminal 20 and the 5GS using a data communication PDU session.

[0049] From S121 to S122, the terminal 20 moves from the 5GS base station 10A to the 6GS base station 10B.

[0050] S121: It is assumed that a policy that gives priority to using 6GS over 5GS in data communication is applied to the terminal 20.

[0051] S122: By moving from 5GS to 6GS, the terminal 20 releases the data communication PDU session in 5GS established in S112.

[0052] The process following S122 will be described. Fig. 4 is a diagram showing an example of a second sequence diagram according to an embodiment of the present invention. The process of each step in Fig. 4 will be described below.

[0053] In steps S201 to S215, a registration procedure for the terminal 20 with the 6GS is performed.

[0054] S201: The terminal 20 transmits to the 6G base station 10B a request message (Registration request) requesting registration of the terminal 20 to the 6GS.

[0055] S202: The base station 10B transmits to the 6GAMF 30D a request message (Registration request) requesting registration of the terminal 20 with the 6GS.

[0056] S203: 6GAMF30D assumes that there is a policy that allows dual registration operation in two systems, 5GS and 6GS, from the UDM perspective.

[0057] S204: The 6GAMF30D transmits to the UDM30G a request message (Nudm_UECM_Registration request) requesting registration of the terminal 20 in 6GS. This request message is expressed, for example, as Nudm_UECM_Registration request (6GAmf3GppAccessRegistration(5g6gDrFlag=1)). 6GAmf3GppAccessRegistration is a newly defined data type that includes information about the terminal 20 to be registered in 6GS, including content similar to that of Amf3GppAccessRegistration, which is information about the terminal 20 to be registered in 5GS described in S104 of FIG. 3. This data type includes information (5g6gDrFlag=1) indicating that registration in two systems, 5GS and 6GS (dual registration), is possible.

[0058] S205: UDM30G registers terminal 20 with 6GS by associating and storing the subscriber identifier (SUPI) of terminal 20 to be registered, which is included in the request message received in S204, with information about 6GAMF30D that controls terminal 20. That is, UDM30G associates and stores the subscriber identifier (SUPI) of terminal 20, information about AMF30A, and information about 6GAMF30D.

[0059] S206: The UDM 30G does not erase the information about the AMF 30A stored in association with the terminal 20 (subscriber identifier) ​​registered with the 5GS in S105 of Fig. 3. In other words, the UDM 30G does not cancel the terminal registration in the 5GS for the terminal 20 with the same subscriber identifier.

[0060] S207: UDM30G determines, for example, based on the subscriber identifier (SUPI), that registration of terminal 20 has already been performed by AMF30A, and decides to send information related to AMF30A (for example, an instance ID or identifier that indicates the destination of the message) to 6GAMF30D in order to coordinate terminal registration between AMF30A and 6GAMF30D.

[0061] S208: The UDM30G sends a response message (Nudm_UECM_Registration response) to the 6GAMF30D in response to the request message received in S204. The response message includes the instance ID of the AMF30A, which is the duplicate registration collaboration destination notified to the 6GAMF30D for collaboration between the AMF30A and the 6GAMF30D. The request message is expressed as, for example, Nudm_UECM_Registration response (6gAmf3GppAccessRegistration (5g6gDrFlag=1, duplicate registration collaboration destination instance ID)).

[0062] S209: The 6GAMF30D sets, with regard to the registration of the terminal 20, information indicating that the terminal 20 is in the 6GS area (6G area flag=1).

[0063] S210: The 6GAMF 30D determines to perform collaboration regarding the registration of the terminal 20 with the AMF 30A, which is the overlapping registration collaboration destination.

[0064] S211: The 6GAMF 30D transmits to the AMF 30A a request message (Namf_Association_Create request) requesting settings related to cooperation between the AMF 30D and the 6GAMF 30D regarding the terminal 20. The request message includes information indicating that the terminal 20 is in the 6GS area, and is expressed as, for example, Namf_Association_Create request (6G area flag=1).

[0065] S212: The AMF 30A recognizes the 6GAMF 30D as the cooperation destination in response to the request message received in S211. The AMF 30A also includes information indicating that the terminal 20 is within the 6GS area (6G area coverage flag = 1) in the information associated with the AMF 30A and registered in the UDM 30G, which was stored in S107 of Fig. 3 .

[0066] S213: The AMF 30A sends to the 6GAMF 30D a response message (Namf_Association_Create response) indicating that the association requested in the request message received in S211 is accepted.

[0067] S214: The 6GAMF 30D transmits a response message (Registration Acceptance) to the request message received in S202 to the 6G base station 10B. The response message includes information indicating that cooperation between the AMF 30A and the 6GAMF 30D has been established.

[0068] S215: The 6G base station 10B transmits a response message (Registration Acceptance) in response to the request message received in S201 to the terminal 20. The response message includes information indicating that cooperation between the AMF 30A and the 6G 6G base station 10B has been established.

[0069] In steps S221 to S222, a procedure for establishing a PDU session is executed between the terminal 20 and the 6GS.

[0070] S221: A PDU session for data communication is established between the terminal 20 and the 6GS.

[0071] S222: Communication is performed between the terminal 20 and the 6GS using a data communication PDU session.

[0072] The process following S222 will be described. Fig. 5 is a diagram showing an example of a third sequence diagram according to an embodiment of the present invention. The process of each step in Fig. 5 will be described below.

[0073] Processing for an incoming voice call in 5GS is executed from S301 in FIG. 5 to S420 in FIG. 6.

[0074] S301: UPF30C receives a message (SIP INVITE) including information indicating an incoming voice call as DL user data on the user data path of an IMS PDU session in 5GS.

[0075] S302: UPF 30C transmits a message (PFCP Session Report request) reporting downlink data to SMF 30B.

[0076] S303: SMF 30B sends a request message (Namf_Communication_N1N2MessageTransfer request) to AMF 30A requesting the establishment of a user data path between UPF 30C and the base station for delivering downlink data.

[0077] S304: AMF 30A sends a response message (Namf_Communication_N1N2MessageTransfer response) to SMF 30B in response to the request message received in S303.

[0078] S305: AMF 30A recognizes that the PDU session that received the downlink data is an IMS PDU session. Since the information stored in S212 of Fig. 4 includes information indicating that the terminal 20 is in a 6G area (6G area flag = 1), AMF 30A determines not to call the terminal 20 by 5GS but by 6GS.

[0079] S306: AMF30A includes information indicating that a voice call is being received in 5GS (5G voice call receiving flag = 1) in the information associated with its own device and registered in UDM30G, which was stored in S107 of Figure 3.

[0080] S307: The AMF 30A transmits to the 6GAMF 30D a request message (Namf_Association_Update request) requesting a call to the terminal 20. The request message includes information indicating that an incoming voice call is being received in 5GS (5G incoming voice call flag = 1).

[0081] S308: 6GAMF30D includes information indicating that the terminal 20 is receiving a voice call on 5GS (5G voice call in progress flag = 1) in the information associated with its own device and registered in UDM30G, which was stored in S212 of Figure 4.

[0082] S309: The 6GAMF 30D sends a response message (Namf_Association_Update response) to the request message received in S307 to the AMF 30A.

[0083] The process following S309 will be described. Fig. 6 is a diagram showing an example of a fourth sequence diagram according to an embodiment of the present invention. The process of each step in Fig. 6 will be described below.

[0084] S400: Since the terminal 20 is receiving a voice call in the 5GS, the 6GAMF30D determines to have the terminal 20 execute a service request in the 5GS to respond to the voice call and to activate an IMS PDU session.

[0085] Steps S401 and S402 are processes that are executed when the terminal 20 is communicating in 6GS (connection mode).

[0086] S401: The 6GAMF 30D transmits to the 6G base station 10B a message (Downlink NAS Transport, see section 9.3.5.2 of Non-Patent Document 4) including a request to respond to an incoming voice call in a system (5GS) other than the currently communicating system (6GS). The message includes information indicating that the wireless access type is a wireless system used in 5GS (RAT type=NR) and information indicating that the purpose of the message is to notify that an incoming voice call is in progress in 5GS. The message is expressed as, for example, Downlink NAS Transport(NAS-PDU(Notification(Access Type=3GPP access, RAT type=NR, Purpose=5G voice call in progress))) (see section 8.2.23.1 of Non-Patent Document 5, etc.).

[0087] S402: The 6G base station 10B transmits a message (DL Information Transfer) for transferring the information received in S401 to the terminal 20. This message is expressed as, for example, DL Information Transfer (dedicated NAS-Message (Notification (Access Type = 3GPP access, RAT type = NR, Purpose = 5G voice incoming call))).

[0088] S403 and S404 are processes executed when the terminal 20 is in the idle mode in 6GS.

[0089] S403: The 6GAMF 30D transmits to the 6G base station 10B a paging message (Paging) to call the terminal 20 in idle mode. The message includes a request to respond to an incoming voice call in a system (5GS) other than the currently camped system (6GS), information indicating that the wireless access type is wireless used in 5GS (RAT type=NR), and information indicating that the purpose of the message is to notify that an incoming voice call is in progress in 5GS.

[0090] S404: The 6G base station 10B transmits to the terminal 20 a paging message (Paging) generated from the message received in S403, for calling the terminal 20 in idle mode.

[0091] S405: In response to the message received in S402 or S404, the terminal 20 determines to switch from 6GS to 5GS by an automatic response by the terminal 20 or by an operation by the user.

[0092] S406: Following S402, the procedures of S406 and S410 to S418 are executed. The terminal 20 transmits a message (UL Information Transfer) including information indicating switching to 5GS to the 6G base station 10B. This message is expressed as, for example, UL Information Transfer (dedicated NAS-Message (Notification response (switching to 5G))).

[0093] S407: The terminal 20 switches the connected system from 6GS to 5GS, and determines to execute a service request and IMS PDU session activation.

[0094] S408: The terminal 20 transmits a message (service request) requesting a response to the incoming voice call to the base station 10A based on the procedure of the existing specifications.

[0095] S409: The base station 10A transmits the message (service request) received in S408 to the AMF 30A.

[0096] S410: The 6G base station 10B transmits to the 6GAMF 30D a message (Uplink NAS Transport) including information indicating switching to 5GS received in S406. This message is expressed as, for example, Uplink NAS Transport (NAS-PDU (Notification response (switching to 5G))).

[0097] S411: 6GAMF30D decides to deactivate the 6G data communication PDU session.

[0098] S412: The 6GAMF30D sends a request message (UE Context Release Command) to the 6G base station 10B requesting the release of the terminal context.

[0099] S413: The 6G base station 10B transmits to the 6GAMF30D a response message (UE Context Release Complete) in response to the request message received in S412.

[0100] S414: 6GAMF30D sends a request message (Nsmf_PDUSession_UpdateSMContext request) to 6GSMF30E regarding the deactivation of the PDU session for 6G data communication.

[0101] S415: 6GSMF30E sends a request message (PFCP modification request) regarding the deactivation of the 6G data communication PDU session to 6GUPF30F.

[0102] S416: The 6GUPF30F performs deactivation of the 6G data communication PDU session.

[0103] S417: The 6GUPF30F transmits to the 6GSMF30E a response message (PFCP modification response) in response to the request message received in S415.

[0104] S418: The 6GSMF30E sends to the 6GAMF30D a response message (Nsmf_PDUSession_UpdateSMContext response) in response to the request message received in S414.

[0105] S419: AMF30A erases the information indicating that a voice call is being received on 5GS and the information indicating that the terminal 20 is in the 6G area from the registration information for UDM30G stored in its own device.

[0106] S420: The 6GAMF30D erases the information indicating that the terminal 20 is receiving a voice call in 5GS and the information indicating that the terminal 20 is in the 6G area from the registration information for the UDM30G stored in the device itself.

[0107] Next, a procedure for periodic registration will be described. Fig. 7 is a diagram showing an example of a fifth sequence diagram according to an embodiment of the present invention. The processing of each step in Fig. 7 will be described below.

[0108] S501: Based on the information contained in the response message received in S215 indicating that cooperation between AMF30A and 6GAMF30D has been established, terminal 20 recognizes that if periodic registration is performed in either AMF30A or 6GAMF30D, the periodic registration will be valid for both AMF30A and 6GAMF30D.

[0109] S502: The terminal 20 confirms that the periodic registration timer in 5GS (T3512, see section 10.2 of Non-Patent Document 5) has expired. Here, the periodic registration timer in 6GS (T3612) has not expired.

[0110] S503: The terminal 20 determines to perform periodic registration to the 5GS in response to expiration of the periodic registration timer in the 5GS.

[0111] S504: The terminal 20 transmits a request message (Registration request) to the base station 10A requesting periodic registration for 5GS registration.

[0112] S505: The base station 10A sends a request message (Registration request) to the AMF 30A requesting periodic registration for 5GS registration.

[0113] S506: AMF 30A initializes a mobile reachable timer (see section 10.2 of Non-Patent Document 5) used within the AMF 30A.

[0114] S507: The AMF 30A transmits to the 6GAMF 30D a request message (Namf_Association_Update request) requesting notification that access has occurred from the terminal 20. The request message includes information indicating that the AMF 30A is not in a 6G area (6G area flag = 0).

[0115] S508: The 6GAMF30D initializes the mobile reachable timer used within its own device.

[0116] S509: The 6GAMF 30D transmits a response message (Namf_Association_Update response) to the request message received in S507 to the AMF 30A. The response message includes information indicating that the 6G device is not present in the 6G area (6G presence flag = 0).

[0117] S510: The AMF 30A sends a response message (Registration Acceptance) to the base station 10A in response to the request message received in S505. The response message includes information indicating that both the AMF 30A and the 6GAMF 30D have accepted the periodic registration request.

[0118] S511: The base station 10A transmits a response message (Registration Acceptance) in response to the request message received in S504 to the terminal 20. The response message includes information indicating that the periodic registration request has been accepted in both the AMF 30A and the 6GAMF 30D.

[0119] S512: The terminal 20 restarts the periodic registration timer (T3512) in 5GS and the periodic registration timer (T3612) on the 6G side by initializing them.

[0120] The above-described embodiment enables a fallback of the wireless communication system without using a special network node. Furthermore, cooperation between the AMF 30A and the 6GAMF 30D can reduce the amount of signaling and processing load in the network, including access to the UDM 30G and periodic registration of the terminal 20.

[0121] (Device Configuration) Next, a description will be given of an example of the functional configuration of the base station 10, network node 30, and terminal 20 that perform the processes and operations described above. The base station 10, network node 30, and terminal 20 include functions for performing the above-described embodiments. However, the base station 10, network node 30, and terminal 20 may each include only a part of the functions of the embodiments.

[0122] <Base Station 10 and Network Node 30> Fig. 8 is a diagram showing an example of the functional configuration of the base station 10 and the network node 30. As shown in Fig. 8, 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 Fig. 8 is merely an example. As long as the operations according to the embodiment of the present invention can be performed, the names of the functional divisions and functional units may be any. Note that the network node 30 may have the same functional configuration as the base station 10. Furthermore, a network node 30 having multiple different functions in the system architecture may be composed of multiple network nodes 30 separated by function.

[0123] The transmitter 110 includes a function of generating a signal to be transmitted to the terminal 20 or another network node 30 and transmitting the signal by wire or wirelessly. The receiver 120 includes a function of receiving various signals transmitted from the terminal 20 or another network node 30 and acquiring, for example, information of a higher layer from the received signal. A communication unit including the transmitter 110 and the receiver 120 may be configured.

[0124] The setting unit 130 stores in a storage device preset setting information and various setting information to be transmitted to the terminal 20, and reads out from the storage device as needed. The content of the setting information is, for example, information related to a communication path in the IMS data channel network.

[0125] As described in the embodiments, the control unit 140 performs processing to enable communication between the communication device deployed on the satellite and the communication device deployed on the ground. The control unit 140 also performs processing related to communication with the terminal 20. The function unit related to signal transmission in the control unit 140 may be included in the transmitting unit 110, and the function unit related to signal reception in the control unit 140 may be included in the receiving unit 120.

[0126] <Terminal 20> Fig. 9 is a diagram showing an example of the functional configuration of the terminal 20. As shown in Fig. 9, the terminal 20 has a transmitting unit 210, a receiving unit 220, a setting unit 230, and a control unit 240. The functional configuration shown in Fig. 9 is merely an example. As long as the operations related to the embodiment of the present invention can be performed, the names of the functional divisions and functional units may be any. In addition, the communication device that becomes the resource holder 20 may have the same functional configuration as the terminal 20.

[0127] The transmitter 210 creates a transmission signal from transmission data and transmits the transmission signal wirelessly. The receiver 220 receives various signals wirelessly and acquires higher layer signals from the received physical layer signals. The receiver 220 also has a function of receiving control signals, reference signals, etc. transmitted from the network node 30. A communication unit including the transmitter 210 and the receiver 220 may be configured.

[0128] The setting unit 230 stores various pieces of setting information received from the network node 30 by the receiving unit 220 in a storage device and reads them from the storage device as needed. The setting unit 230 also stores setting information that is set in advance. The content of the setting information is, for example, information related to communication paths in the IMS network.

[0129] As described in the embodiments, the control unit 240 performs processing to enable communication between the communication device deployed on the satellite and the communication device deployed on the ground. The function unit related to signal transmission in the control unit 240 may be included in the transmitting unit 210, and the function unit related to signal reception in the control unit 240 may be included in the receiving unit 220.

[0130] (Hardware Configuration) The block diagrams (FIGS. 8 and 9) used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wires, wirelessly, etc.) and these multiple devices. The functional block may be realized by combining software with the single device or the multiple devices.

[0131] Functions include, but are not limited to, judgment, determination, assessment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, consideration, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assignment. For example, a functional block (component) that performs transmission is called a transmitting unit or transmitter. As mentioned above, there are no particular limitations on how these functions are implemented.

[0132] For example, the base station 10, the network node 30, the terminal 20, etc. according to an embodiment of the present disclosure may function as a computer that performs processing of the wireless communication method of the present disclosure. Fig. 10 is a diagram illustrating an example of the hardware configuration of the base station 10 and the terminal 20 according to an embodiment of the present disclosure. The network node 30 may have the same hardware configuration as the base station 10. The above-described base station 10 and the terminal 20 may be physically configured as a computer device including a processor 1001, a storage device 1002, an auxiliary storage device 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0133] In the following description, the term "apparatus" can be interpreted as a circuit, a device, a unit, etc. The hardware configuration of the base station 10 and the terminal 20 may be configured to include one or more of the apparatuses shown in the drawings, or may be configured to exclude some of the apparatuses.

[0134] Each function in the base station 10 and the terminal 20 is realized by loading specified software (programs) onto hardware such as the processor 1001, the memory device 1002, etc., so that the processor 1001 performs calculations, controls communication by the communication device 1004, and controls at least one of reading and writing data in the memory device 1002 and the auxiliary memory device 1003.

[0135] The processor 1001 controls the entire computer by running, for example, an operating system. The processor 1001 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc. For example, the above-mentioned control unit 140, control unit 240, etc. may be realized by the processor 1001.

[0136] The processor 1001 also reads programs (program codes), software modules, data, etc. from at least one of the auxiliary storage device 1003 and the communication device 1004 into the storage device 1002 and executes various processes in accordance with the programs. The programs used are those that cause a computer to execute at least some of the operations described in the above-described embodiments. For example, the control unit 140 of the base station 10 shown in FIG. 8 may be implemented by a control program stored in the storage device 1002 and running on the processor 1001. For example, the control unit 240 of the terminal 20 shown in FIG. 9 may be implemented by a control program stored in the storage device 1002 and running on the processor 1001. While the above-described various processes have been described as being executed by one processor 1001, they may also be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may also be transmitted from a network via a telecommunications line.

[0137] The storage device 1002 is a computer-readable recording medium and may be configured, for example, by at least one of a read-only memory (ROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a random access memory (RAM), etc. The storage device 1002 may also be called a register, a cache, a main memory, etc. The storage device 1002 can store executable programs (program codes), software modules, etc. for implementing a communication method according to an embodiment of the present disclosure.

[0138] The secondary storage device 1003 is a computer-readable recording medium, and may be, for example, at least one of an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray (registered trademark) disk), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy (registered trademark) disk, a magnetic strip, etc. The above-mentioned storage medium may be, for example, a database, a server, or other appropriate medium including at least one of the storage device 1002 and the secondary storage device 1003.

[0139] The communication device 1004 is hardware (transmission / reception device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as, for example, a network device, a network controller, a network card, a communication module, etc. The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, a transmission / reception antenna, an amplifier unit, a transmission / reception unit, a transmission path interface, etc. may be realized by the communication device 1004. The transmission / reception unit may be implemented as a transmission unit and a reception unit that are physically or logically separated.

[0140] The input device 1005 is an input device (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives input from the outside. The output device 1006 is an output device (e.g., a display, a speaker, an LED lamp, etc.) that outputs to the outside. Note that the input device 1005 and the output device 1006 may be integrated into one device (e.g., a touch panel).

[0141] Furthermore, each device such as the processor 1001 and the storage device 1002 is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

[0142] Furthermore, the base station 10 and the terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA), and some or all of the functional blocks may be realized by the hardware. For example, the processor 1001 may be implemented using at least one of these pieces of hardware.

[0143] Fig. 11 shows an example configuration of a vehicle 2001. As shown in Fig. 11, the vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, front wheels 2007, rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021 to 2029, an information service unit 2012, and a communication module 2013. Each aspect / embodiment described in the present disclosure may be applied to a communication device mounted on the vehicle 2001, and may be applied to the communication module 2013, for example.

[0144] The drive unit 2002 is configured, for example, by an engine, a motor, or a hybrid of an engine and a motor. The steering unit 2003 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels and the rear wheels based on the operation of the steering wheel operated by the user.

[0145] The electronic control unit 2010 is composed of a microprocessor 2031, a memory (ROM, RAM) 2032, and a communication port (IO port) 2033. Signals are input to the electronic control unit 2010 from various sensors 2021 to 2029 provided in the vehicle 2001. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0146] The signals from the various sensors 2021 to 2029 include a current signal from a current sensor 2021 that senses the current of the motor, a rotation speed signal of the front and rear wheels obtained by a rotation speed sensor 2022, an air pressure signal of the front and rear wheels obtained by an air pressure sensor 2023, a vehicle speed signal obtained by a vehicle speed sensor 2024, an acceleration signal obtained by an acceleration sensor 2025, an accelerator pedal depression amount signal obtained by an accelerator pedal sensor 2029, a brake pedal depression amount signal obtained by a brake pedal sensor 2026, a shift lever operation signal obtained by a shift lever sensor 2027, and a detection signal for detecting obstacles, vehicles, pedestrians, etc. obtained by an object detection sensor 2028.

[0147] The information service unit 2012 is composed of various devices, such as a car navigation system, an audio system, speakers, a television, and a radio, for providing (outputting) various types of information, such as driving information, traffic information, and entertainment information, and one or more ECUs for controlling these devices. The information service unit 2012 uses information acquired from external devices via the communication module 2013 or the like to provide various types of multimedia information and multimedia services to the occupants of the vehicle 2001. The information service unit 2012 may include input devices (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, a touch panel, etc.) that accept input from the outside, and may also include output devices (e.g., a display, a speaker, an LED lamp, a touch panel, etc.) that output information to the outside.

[0148] The driving assistance system unit 2030 is composed of various devices that provide functions for preventing accidents and reducing the driving burden on the driver, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS, etc.), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps, etc.), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System), etc.), AI (Artificial Intelligence) chips, and AI processors, as well as one or more ECUs that control these devices. In addition, the driving assistance system unit 2030 transmits and receives various information via the communication module 2013 to realize the driving assistance function or the autonomous driving function.

[0149] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via the communication port. For example, the communication module 2013 transmits and receives data via the communication port 2033 to and from the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axle 2009, microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021 to 29, which are provided in the vehicle 2001.

[0150] The communication module 2013 is a communication device that can be controlled by the microprocessor 2031 of the electronic control unit 2010 and can communicate with an external device. For example, it transmits and receives various information to and from the external device via wireless communication. The communication module 2013 may be located either inside or outside the electronic control unit 2010. The external device may be, for example, a base station, a mobile station, or the like.

[0151] The communication module 2013 may transmit at least one of signals from the above-mentioned various sensors 2021-2028 input to the electronic control unit 2010, information obtained based on the signals, and information based on input from the outside (user) obtained via the information service unit 2012 to an external device via wireless communication. The electronic control unit 2010, the various sensors 2021-2028, the information service unit 2012, etc. may be referred to as input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include information based on the above-mentioned input.

[0152] The communication module 2013 receives various information (traffic information, traffic signal information, vehicle-to-vehicle information, etc.) transmitted from external devices and displays it on an information service unit 2012 provided in the vehicle 2001. The information service unit 2012 may be called an output unit that outputs information (for example, outputs information to a device such as a display or speaker based on the PDSCH (or data / information decoded from the PDSCH) received by the communication module 2013). The communication module 2013 also stores the various information received from external devices in a memory 2032 that can be used by the microprocessor 2031. Based on the information stored in the memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axles 2009, sensors 2021 to 2029, etc. provided in the vehicle 2001.

[0153] <Supplementary Notes> (Supplementary Item 1) A network node comprising: a transmitter that transmits to a first network node a first message requesting registration of a terminal in a first communication system that is a communication system including the network node itself; and a receiver that receives from the first network node a second message including an identifier of a second network node in a second communication system and information indicating acceptance of the registration, wherein the transmitter transmits to the second network node a third message requesting configuration related to cooperation, the third message including information indicating that the terminal is within the range of the first communication system, and the receiver receives from the second network node a fourth message indicating acceptance of the cooperation. (Supplementary Item 2) The network node according to Supplementary Item 1, wherein the receiver receives from the second network node a fifth message requesting a call to the terminal, and the transmitter transmits to the terminal a sixth message requesting a response to the call in the first communication system. a receiving unit configured to receive, from a terminal, a first message requesting periodic registration, a control unit configured to initialize a mobile reachability timer used within the own device, and a transmitting unit configured to transmit, to a first network node with which association has been established, a second message notifying that there has been access by the terminal, wherein the receiving unit receives from the first network node a third message in response to the second message, and the transmitting unit transmits to the terminal a fourth message indicating that the periodic registration request has been accepted in both a communication system including the own device and another communication system. (Supplementary Item 4) A network node configured to receive, from a first network node with which association has been established with the own device, a first message notifying that there has been access by the terminal, a control unit configured to initialize a mobile reachability timer used within the own device, and a transmitting unit configured to transmit, to the first network node, a second message in response to the first message.(Supplementary Item 5) A terminal having: a transmitter that transmits a first message requesting periodic registration to a first network node of a first communication system, a receiver that receives from the first network node a second message indicating that the periodic registration request has been accepted in both the first communication system and a second communication system, and a controller that initializes both a periodic registration timer in the first communication system and a periodic registration timer in the second communication system. (Supplementary Item 6) A communication method executed by a network node, comprising: a step of transmitting, to a first network node, a first message requesting registration of the terminal in a first communication system that is a communication system including the terminal itself, a step of receiving, from the first network node, a second message including an identifier of a second network node in the second communication system and information indicating acceptance of the registration, a step of transmitting, to a second network node, a third message requesting configuration related to cooperation, the third message including information indicating that the terminal is within the range of the first communication system, and a step of receiving, from the second network node, a fourth message indicating acceptance of the cooperation.

[0154] Any of Supplementary Items 1 to 6 makes it possible to enable fallback of a system in a wireless communication system without using a special network node.

[0155] (Supplementary Notes on the Embodiments) Although the embodiments of the present invention have been described above, the disclosed invention is not limited to such embodiments, and those skilled in the art will understand various modifications, alterations, alternatives, and substitutions. While specific numerical examples have been used to facilitate understanding of the invention, unless otherwise specified, these numerical values ​​are merely examples, and any appropriate values ​​may be used. The division of items in the above description is not essential to the present invention; matters described in two or more items may be used in combination as needed, and matters described in one item may apply to matters described in another item (as long as there is no contradiction). Boundaries between functional units or processing units in functional block diagrams do not necessarily correspond to boundaries between physical components. The operations of multiple functional units may be performed by a single physical component, or the operations of a single functional unit may be performed by multiple physical components. The order of processing steps described in the embodiments may be reversed as long as there is no contradiction. For convenience of processing description, the base station 10 and terminal 20 have been described using functional block diagrams, but such devices may be realized by hardware, software, or a combination thereof. The software operated by the processor of the base station 10 in accordance with an embodiment of the present invention and the software operated by the processor of the terminal 20 in accordance with an embodiment of the present invention may each be stored in random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, register, hard disk (HDD), removable disk, CD-ROM, database, server, or any other suitable storage medium.

[0156] Furthermore, the notification of information is not limited to the aspects / embodiments described in the present disclosure, and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, Medium Access Control (MAC) signaling), broadcast information (Master Information Block (MIB), System Information Block (SIB)), other signals, or a combination thereof. Furthermore, the RRC signaling may be referred to as an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, or the like.

[0157] Each aspect / embodiment described in the present disclosure may be implemented using any of the following standards: LTE (Long Term Evolution), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (xG (x is, for example, an integer or a decimal number)), FRA (Future Radio Access), NR (new Radio), New radio access (NX), Future generation radio access (FX), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.17 (WiMAX (registered trademark)), IEEE 802.19 (WiMAX (registered trademark)), IEEE 802.20 (WiMAX (registered trademark)), IEEE 802.21 (Wi-Fi (registered trademark)), IEEE 802.22 (WiMAX (registered trademark)), IEEE 802.23 (WiMAX (registered trademark)), IEEE 802.24 (WiMAX (registered trademark)), IEEE 802.25 (WiMAX (registered trademark)), IEEE 802.26 (WiMAX (registered trademark)), IEEE 802.27 (WiMAX (registered trademark)), IEEE 802.28 (WiMAX (registered trademark)), IEEE 802.29 (WiMAX (registered trademark)), IEEE 802.30 (WiMAX (registered trademark)), IEEE 802.31 (Wi-Fi (registered trademark)), IEEE 802.32 (WiMAX (registered trademark)), IEEE 802.33 (WiMAX (registered trademark)), IEEE 802.34 ( The present invention may be applied to at least one of systems using 802.20, UWB (Ultra-Wide Band), Bluetooth (registered trademark), or other suitable systems, and next-generation systems that are extended, modified, created, or defined based on these systems. The present invention may also be applied to a combination of multiple systems (e.g., a combination of LTE and / or LTE-A with 5G).

[0158] The order of the procedures, sequences, flowcharts, etc. of each aspect / embodiment described herein may be rearranged unless it is consistent. For example, the methods described in this disclosure present elements of various steps using an example order and are not limited to the particular order presented.

[0159] In this specification, a specific operation described as being performed by the base station 10 may be performed by its upper node in some cases. In a network consisting of one or more network nodes having the base station 10, it is clear that various operations performed for communication with the terminal 20 may be performed by at least one of the base station 10 and another network node other than the base station 10 (such as, but not limited to, an MME or an S-GW). Although the above example illustrates a case where there is one other network node other than the base station 10, the other network node may be a combination of multiple other network nodes (such as an MME and an S-GW).

[0160] The information, signals, etc. described in the present disclosure may be output from a higher layer (or a lower layer) to a lower layer (or a higher layer), or may be input / output via multiple network nodes.

[0161] Input and output information may be stored in a specific location (for example, memory) or may be managed using a management table. Input and output information may be overwritten, updated, or added to. Output information may be deleted. Input information may be transmitted to another device.

[0162] In the present disclosure, the determination may be made by a value represented by one bit (0 or 1), by a Boolean value (true or false), or by a comparison of numerical values ​​(e.g., comparison with a predetermined value).

[0163] Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0164] Software, instructions, information, etc. may also be transmitted or received over a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared, microwave), then these wired and / or wireless technologies are included within the definition of transmission media.

[0165] The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0166] Note that terms described in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of a channel and a symbol may be a signal (signaling). Furthermore, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

[0167] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0168] Furthermore, the information, parameters, etc. described in the present disclosure may be expressed using absolute values, may be expressed using relative values ​​from a predetermined value, or may be expressed using other corresponding information. For example, a radio resource may be indicated by an index.

[0169] The names used for the above-described parameters are not intended to be limiting in any way. Furthermore, the mathematical expressions using these parameters may differ from those explicitly disclosed in this disclosure. The various channels (e.g., PUCCH, PDCCH, etc.) and information elements may be identified by any suitable names, and therefore the various names assigned to these various channels and information elements are not intended to be limiting in any way.

[0170] In the present disclosure, terms such as "base station (BS)," "radio base station," "base station device," "fixed station," "NodeB," "eNodeB (eNB)," "gNodeB (gNB)," "access point," "transmission point," "reception point," "transmission / reception point," "cell," "sector," "cell group," "carrier," and "component carrier" may be used interchangeably. A base station may also be referred to by terms such as a macrocell, a small cell, a femtocell, and a picocell.

[0171] A base station can accommodate one or more (e.g., three) cells. When a base station accommodates multiple cells, the overall coverage area of ​​the base station can be partitioned into multiple smaller areas, and each smaller area can also be provided with communication services by a base station subsystem (e.g., a small indoor base station (RRH: Remote Radio Head)). The terms "cell" or "sector" refer to part or all of the coverage area of ​​a base station and / or base station subsystem that provides communication services within that coverage.

[0172] In the present disclosure, the base station transmitting information to a terminal may be interpreted as the base station instructing the terminal to control or operate based on the information.

[0173] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," and the like may be used interchangeably.

[0174] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other suitable terminology.

[0175] At least one of the base station and the mobile station may be referred to as a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may be a device mounted on a mobile object, the mobile object itself, etc. The mobile object refers to a movable object, and may move at any speed. Naturally, this also includes cases where the mobile object is stationary. Examples of the mobile object include, but are not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcars, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and objects mounted thereon. The mobile object may also be a mobile object that moves autonomously based on an operational command. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile object (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may be a device that does not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0176] Furthermore, a base station in the present disclosure may be read as a user terminal. For example, the aspects / embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between multiple terminals 20 (which may be called, for example, Device-to-Device (D2D) or Vehicle-to-Everything (V2X)). In this case, the terminal 20 may be configured to have the functions of the base station 10 described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, terms such as an uplink channel and a downlink channel may be read as a side channel.

[0177] Similarly, the user terminal in the present disclosure may be read as a base station, in which case the base station may be configured to have the functions of the user terminal described above.

[0178] As used in this disclosure, the terms "determining" and "determining" may encompass a wide variety of actions. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiring (e.g., searching in a table, database, or other data structure), ascertaining, and the like. "Determining" and "determining" may also include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), and the like. Furthermore, "judgment" and "decision" can include regarding resolving, selecting, choosing, establishing, comparing, etc. as having been "judged" or "decided." In other words, "judgment" and "decision" can include regarding some action as having been "judged" or "decided." Furthermore, "judgment (decision)" can be interpreted as "assuming," "expecting," "considering," etc.

[0179] The terms "connected," "coupled," or any variation thereof, refer to any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access." As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using one or more wires, cables, and / or printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

[0180] The reference signal may be abbreviated as RS (Reference Signal) or may be called a pilot depending on the applicable standard.

[0181] As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0182] As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must in some way precede the second element.

[0183] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0184] When the terms "include," "including," and variations thereof are used in this disclosure, these terms are intended to be inclusive, similar to the term "comprising." Furthermore, when the term "or" is used in this disclosure, it is not intended to be an exclusive or.

[0185] In this disclosure, where articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0186] In the present disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "coupled" may also be interpreted in the same way as "different."

[0187] The aspects / embodiments described in this disclosure may be used alone, in combination, or switched depending on the implementation. Notification of predetermined information (e.g., notification that "X is true") is not limited to explicit notification, but may be implicit (e.g., not notifying the predetermined information).

[0188] Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure.

[0189] 10 Base station 110 Transmitter 120 Receiver 130 Setting unit 140 Control unit 20 Terminal 210 Transmitter 220 Receiver 230 Setting unit 240 Control unit 30 Network node 1001 Processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication device 1005 Input device 1006 Output device 2001 Vehicle 2002 Drive unit 2003 Steering unit 2004 Accelerator pedal 2005 Brake pedal 2006 Shift lever 2007 Front wheels 2008 Rear wheels 2009 Axle 2010 Electronic control unit 2012 Information service unit 2013 Communication module 2021 Current sensor 2022 RPM sensor 2023 Tire pressure sensor 2024 Vehicle speed sensor 2025 Acceleration sensor 2026 Brake pedal sensor 2027 Shift lever sensor 2028 Object detection sensor 2029 Accelerator pedal sensor 2030 Driving assistance system unit 2031 Microprocessor 2032 Memory (ROM, RAM) 2033 Communication port (IO port)

Claims

1. A network node comprising: a transmitter that transmits to a first network node a first message requesting registration of a terminal in a first communication system that is a communication system including the network node itself; and a receiver that receives from the first network node a second message including an identifier of a second network node in a second communication system and information indicating acceptance of the registration, wherein the transmitter transmits to the second network node a third message requesting configuration related to cooperation, including information indicating that the terminal is within the range of the first communication system; and the receiver receives from the second network node a fourth message indicating acceptance of the cooperation.

2. The network node according to claim 1, wherein the receiving unit receives a fifth message from the second network node requesting a call to the terminal, and the transmitting unit transmits a sixth message to the terminal requesting a response to the call in the first communication system.

3. A network node comprising: a receiving unit that receives a first message requesting periodic registration from a terminal; a control unit that initializes a mobile reachability timer used within the device; and a transmitting unit that transmits a second message to a first network node with which cooperation has been established, notifying that the terminal has accessed the node, wherein the receiving unit receives a third message in response to the second message from the first network node, and the transmitting unit transmits a fourth message to the terminal indicating that the periodic registration request has been accepted in both a communication system including the device itself and another communication system.

4. A network node having a receiving unit that receives a first message from a first network node that has established association with the network node, notifying that a terminal has accessed the network node; a control unit that initializes a mobile reachability timer used within the network node; and a transmitting unit that transmits a second message to the first network node in response to the first message.

5. A terminal having: a transmitting unit that transmits a first message requesting periodic registration to a first network node of a first communication system; a receiving unit that receives a second message from the first network node indicating that the periodic registration request has been accepted in both the first communication system and a second communication system; and a control unit that initializes both a periodic registration timer in the first communication system and a periodic registration timer in the second communication system.

6. A communication method executed by a network node, comprising: a step of sending a first message to a first network node requesting registration of a terminal in a first communication system that is a communication system including the network node; a step of receiving a second message from the first network node, the second message including an identifier of a second network node in a second communication system and information indicating acceptance of the registration; a step of sending a third message to the second network node requesting configuration related to cooperation, the third message including information indicating that the terminal is present in the first communication system; and a step of receiving a fourth message from the second network node indicating acceptance of the cooperation.

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