User equipment (UE)

Abstract

This UE is capable of communicating with a satellite equipped with a base station function. The UE transmits information to the satellite indicating that an S&F mode is supported; receives from the satellite information indicating that a registration request message has been stored, information indicating that the feeder link is not available, and a timer value; sets the timer value to a timer; starts the timer; and stops the timer in operation upon receiving information indicating that the registration request message has been transferred.

Description

UE (User Equipment)

[0001] The present invention relates to UE (User Equipment). This application claims priority to Japanese Patent Application No. 2024-001729, filed on January 10, 2024, the contents of which are incorporated herein by reference.

[0002] The 3GPP (3rd Generation Partnership Project: registered trademark) is studying the system architecture of the 5G System (5GS), a fifth-generation (5G) mobile communication system, and is discussing how to support new procedures and new functions (see Non-Patent Documents 1 and 2).

[0003] 3GPP TS 24.501 V18.5.0 (2023-12); 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3; (Release 18)3GPP TS 24.301 V18.5.0 (2023-12); 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3; (Release 18)3GPP TR 23.700-29 V0.2.0 (2023-11); 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; 19)

[0004] Release 19 is expected to consider Store and Forward (also called S&F) satellite operation, but does not disclose how this operation will be realized (see Non-Patent Document 3).

[0005] One aspect of the present invention has been made in consideration of the above circumstances, and aims to clarify how store and forward satellite operations are implemented and to clarify the detailed behavior of UEs, satellites, and / or networks.

[0006] A UE of one embodiment of the present invention is a UE equipped with a transceiver unit and a control unit, wherein the UE is capable of communicating with a satellite equipped with base station functionality, the transceiver unit transmits information to the satellite indicating that it supports S&F mode, and receives from the satellite information indicating that it has stored a registration request message, information indicating that a feeder link is not available, and a timer value, the control unit sets the timer value in a timer and starts the timer, and when the transceiver unit receives information indicating that it has forwarded the registration request message, the control unit stops the timer that is running.

[0007] According to one aspect of the present invention, it is possible to clarify how store and forward satellite operations are implemented, and to clarify the detailed behavior of the UE, and / or satellite, and / or network.

[0008] FIG. 1 is a diagram for explaining an overview of a mobile communication system (EPS / 5GS). FIG. 2 is a diagram for explaining a detailed configuration of a mobile communication system (EPS / 5GS). FIG. 3 is a diagram for explaining the device configuration of a UE. FIG. 4 is a diagram for explaining the configuration of an access network device. FIG. 5 is a diagram for explaining the configuration of a core network device.

[0009] Hereinafter, a best mode for carrying out one aspect of the present invention will be described with reference to the drawings. In this embodiment, an embodiment of a mobile communication system to which one aspect of the present invention is applied will be described as an example.

[0010] [1. System Overview] First, FIG. 1 is a diagram for explaining an overview of a mobile communication system 1 used in each embodiment, and FIG. 2 is a diagram for explaining a detailed configuration of the mobile communication system 1.

[0011] FIG. 1 shows that the mobile communication system 1 is composed of UE_A10, access network _A80, core network _A90, PDN (Packet Data Network) _A5, access network _B120, core network _B190, and DN (Data Network) _A6.

[0012] In the following, these devices and functions may be referred to by abbreviating the symbols, such as UE, access network_A, core network_A, PDN, access network_B, core network_B, DN, etc.

[0013] Figure 2 also shows devices and functions such as UE_A10, E-UTRAN80, MME40, SGW35, PGW-U30, PGW-C32, PCRF60, HSS50, 5G AN120, AMF140, UPF130, SMF132, PCF160, UDM150, and N3IWF170, as well as interfaces that connect these devices and functions to each other.

[0014] In the following, these devices and functions may be referred to by abbreviated symbols such as UE, E-UTRAN, MME, SGW, PGW-U, PGW-C, PCRF, HSS, 5G AN, AMF, UPF, SMF, PCF, UDM, N3IWF, etc.

[0015] The 4G system EPS (Evolved Packet System) includes an access network A and a core network A, but may further include a UE and / or a PDN. The 5G system 5GS (5G System) includes a UE, an access network B, and a core network B, but may further include a DN.

[0016] A UE is a device that can connect to a network service via 3GPP access (also referred to as a 3GPP access network, or 3GPP AN) and / or non-3GPP access (also referred to as a non-3GPP access network, or non-3GPP AN). A UE may be a terminal device capable of wireless communication, such as a mobile phone or a smartphone, or may be a terminal device that can connect to EPS and / or 5GS. A UE may include a UICC (Universal Integrated Circuit Card) or an eUICC (Embedded UICC). Note that a UE may also be referred to as a user device or a terminal device.

[0017] Furthermore, access network_A corresponds to an E-UTRAN (Evolved Universal Terrestrial Radio Access Network) and / or a wireless LAN access network. One or more eNBs (evolved Node Bs) 45 are deployed in the E-UTRAN. Note that, hereinafter, the eNB 45 may be referred to by abbreviating the symbol eNB. If there are multiple eNBs, the eNBs are connected to each other, for example, via an X2 interface. Furthermore, one or more access points are deployed in the wireless LAN access network.

[0018] Furthermore, access network_B corresponds to a 5G access network (5G AN). The 5G AN is composed of an NG-RAN (NG Radio Access Network) and / or a non-3GPP access network. One or more gNBs (NR NodeBs) 122 are deployed in the NG-RAN. Note that, hereinafter, the symbol for gNB 122 may be abbreviated, such as gNB. The gNB is a node that provides the NR (New Radio) user plane and control plane to UEs, and is a node that connects to the 5GCN via an NG interface (including an N2 interface or an N3 interface). In other words, the gNB is a base station device newly designed for 5GS, and has different functions from the base station device (eNB) designed for the 4G system EPS. Furthermore, when there are multiple gNBs, the gNBs are connected to each other, for example, via an Xn interface.

[0019] Furthermore, the non-3GPP access network may include an untrusted non-3GPP access network and a trusted non-3GPP access network. Here, the untrusted non-3GPP access network may be a non-3GPP access network that does not perform security management within the access network, such as a public wireless LAN. On the other hand, the trusted non-3GPP access network may be an access network specified by 3GPP, and may include a trusted non-3GPP access point (TNAP) and a trusted non-3GPP gateway function (TNGF).

[0020] In the following, E-UTRAN and NG-RAN may be referred to as 3GPP access. Also, wireless LAN access networks and non-3GPP AN may be referred to as non-3GPP access. Also, nodes located in access network_B may be collectively referred to as NG-RAN nodes.

[0021] In addition, in the following, access network _A, access network _B, and devices included in access network _A, and devices included in access network _B may be referred to as access networks, or access network devices, or devices within the access network.

[0022] The core network_A corresponds to an EPC (Evolved Packet Core), which includes, for example, an MME (Mobility Management Entity), an SGW (Serving Gateway), a PGW (Packet Data Network Gateway)-U, a PGW-C, a PCRF (Policy and Charging Rules Function), and an HSS (Home Subscriber Server).

[0023] Furthermore, the core network_B corresponds to a 5G Core Network (5GCN). In the 5GCN, for example, an Access and Mobility Management Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), a Policy Control Function (PCF), a Unified Data Management (UDM), etc. are arranged. Here, the 5GCN may be expressed as a 5GC.

[0024] In addition, in the following, core network _A, core network _B, and devices included in core network _A, and devices included in core network _B may be referred to as core networks, or core network devices, or devices within the core network.

[0025] The core network (core network _A and / or core network _B) may be an IP mobile communication network operated by a mobile network operator (MNO) that connects the access network (access network _A and / or access network _B) to the PDN and / or DN, or it may be a core network for a mobile network operator that operates and manages the mobile communication system 1, or it may be a core network for a virtual mobile communication operator or virtual mobile communication service provider such as an MVNO (Mobile Virtual Network Operator) or MVNE (Mobile Virtual Network Enabler).

[0026] Also, while FIG. 1 illustrates a case where the PDN and the DN are the same, they may be different. The PDN may be a DN (Data Network) that provides communication services to the UE. The DN may be configured as a packet data service network, or may be configured for each service. Furthermore, the PDN may include a connected communication terminal. Therefore, connecting to the PDN may mean connecting to a communication terminal or a server device located in the PDN. Furthermore, transmitting and receiving user data to and from the PDN may mean transmitting and receiving user data to and from a communication terminal or a server device located in the PDN. The PDN may be expressed as the DN, and the DN may be expressed as the PDN.

[0027] In addition, hereinafter, at least a portion of the access network _A, core network _A, PDN, access network _B, core network _B, and DN, and / or one or more devices included therein may be referred to as a network (also referred to as NW) or network device. In other words, when a network and / or network device sends and receives messages and / or performs procedures, it means that at least a portion of the access network _A, core network _A, PDN, access network _B, core network _B, and DN, and / or one or more devices included therein send and receive messages and / or perform procedures.

[0028] The UE can also be connected to an access network. The UE can also be connected to a core network via the access network. The UE can also be connected to a PDN or DN via the access network and the core network. That is, the UE can transmit and receive (communicate) user data with the PDN or DN. When transmitting and receiving user data, not only IP (Internet Protocol) communication but also non-IP communication may be used.

[0029] Here, IP communication refers to data communication using IP, and data is transmitted and received using IP packets. An IP packet is composed of an IP header and a payload portion. The payload portion may include data transmitted and received by devices and functions included in EPS or devices and functions included in 5GS. Non-IP communication refers to data communication that does not use IP, and data is transmitted and received in a format different from the IP packet structure. For example, non-IP communication may be data communication achieved by transmitting and receiving application data without an IP header, or may be user data transmitted and received by a UE with a different header such as a MAC header or an Ethernet (registered trademark) frame header.

[0030] In addition, access network _A, core network _A, access network _B, core network _B, PDN_A, and DN_A may be configured with devices not shown in Fig. 2. For example, core network _A and / or core network _B may include an AUSF (Authentication Server Function) and an AAA (Authentication, authorization, and accounting) server (AAA-S).

[0031] Here, the AUSF is a core network device having an authentication function for 3GPP access and non-3GPP access, specifically, a network function unit that receives an authentication request for 3GPP access and / or non-3GPP access from a UE and executes the authentication procedure.

[0032] The AAA server is a device that has authentication, authorization, and accounting functions and is connected to the AUSF directly or indirectly via another network device. The AAA server may be a network device within the core network. The AAA server may not be included in the core network _A and / or core network _B, but may be included in the PLMN. In other words, the AAA server may be a core network device or a device outside the core network. For example, the AAA server may be a server device within the PLMN managed by a third party.

[0033] 2, for the sake of simplicity, each device and function is shown one by one, but multiple similar devices and functions may be configured in the mobile communication system 1. Specifically, the mobile communication system 1 may be configured with multiple devices and functions such as UE_A10, E-UTRAN80, MME40, SGW35, PGW-U30, PGW-C32, PCRF60, HSS50, 5G AN120, AMF140, UPF130, SMF132, PCF160, and / or UDM150.

[0034] [2. Configuration of Each Device] Next, the configuration of each device (UE, and / or access network device, and / or core network device) used in each embodiment will be described with reference to the drawings. Each device may be configured as physical hardware, as logical (virtual) hardware configured on general-purpose hardware, or as software. Furthermore, at least a part (including all) of the functions of each device may be configured as physical hardware, logical hardware, or software.

[0035] Note that each memory unit (memory unit_A340, memory unit_B540, memory unit_B740) in each device / function mentioned below is configured with, for example, a semiconductor memory, a solid state drive (SSD), a hard disk drive (HDD), etc. Each memory unit can store not only information originally set at the time of shipment, but also various information transmitted and received between the device / function other than the device / function itself (e.g., UE, and / or access network device, and / or core network device, and / or PDN, and / or DN). Each memory unit can also store identification information, control information, flags, parameters, etc. included in control messages transmitted and received in various communication procedures described below. Each memory unit may also store this information for each UE. Furthermore, when interworking between 5GS and EPS is performed, each memory unit can store control messages and user data transmitted and received between the device / function included in 5GS and / or EPS. In this case, not only those transmitted and received via the N26 interface but also those transmitted and received without via the N26 interface can be stored.

[0036] [2.1. Device configuration of UE] First, an example of the device configuration of UE (User Equipment) will be explained using Figure 3. The UE is composed of a control unit _A300, an antenna 310, a transceiver unit _A320, and a memory unit _A340. The control unit _A300, the transceiver unit _A320, and the memory unit _A340 are connected via a bus. The transceiver unit _A320 is connected to the antenna 310.

[0037] The control unit _A300 is a functional unit that controls the operation and functions of the entire UE. The control unit _A300 realizes various processing in the UE by reading and executing various programs stored in the memory unit _A340 as needed.

[0038] The transceiver unit _A320 is a functional unit for wireless communication with a base station device (eNB or gNB) in the access network via an antenna. That is, the UE can use the transceiver unit _A320 to transmit and receive user data and / or control information between an access network device, and / or a core network device, and / or a PDN, and / or a DN.

[0039] Explaining in detail with reference to Figure 2, the UE can communicate with a base station device (eNB) in the E-UTRAN via the LTE-Uu interface by using the transceiver unit _A320. The UE can also communicate with a base station device (gNB) in the 5G AN by using the transceiver unit _A320. The UE can also transmit and receive AMF and NAS (Non-Access-Stratum) messages via the N1 interface by using the transceiver unit _A320. However, since the N1 interface is logical, in reality, communication between the UE and the AMF is performed via the 5G AN.

[0040] The memory unit _A340 is a functional unit for storing programs, user data, control information, etc. necessary for each operation of the UE. The memory unit _340 may also have the function of storing control information transmitted and received between an access network device, a core network device, and a DN.

[0041] The UE may also be capable of communicating with a satellite equipped with the functionality of a base station device.

[0042] [2.2. Device Configuration of Base Station Device] Next, an example of the device configuration of a base station device will be described using Figure 4. The base station device may be a gNB, or an eNB, or an en-gNB, or an ng-eNB. Here, the base station device will be described using a gNB as an example. That is, in the following description, gNB may be read as eNB, or an en-gNB, or an ng-eNB. The gNB is composed of a control unit _B500, an antenna 510, a network connection unit _B520, a transceiver unit _B530, and a memory unit _B540. The control unit _B500, the network connection unit _B520, the transceiver unit _B530, and the memory unit _B540 are connected via a bus. The transceiver unit _B530 is connected to the antenna 510.

[0043] The control unit _B500 is a functional unit that controls the operation and functions of the entire gNB. The control unit _B500 realizes various processes in the gNB by reading and executing various programs stored in the memory unit _B540 as necessary.

[0044] The network connection unit _B520 is a functional unit for the gNB to communicate with the AMF and / or UPF. That is, the gNB can send and receive user data and / or control information between the AMF and / or UPF using the network connection unit _B520.

[0045] The transceiver unit _B530 is a functional unit for wireless communication with the UE via the antenna 510. That is, the gNB can transmit and receive user data and / or control information to and from the UE using the transceiver unit _B530.

[0046] 2, a gNB in ​​a 5G AN can communicate with an AMF via an N2 interface by using a network connection unit _B 520, and can communicate with a UPF via an N3 interface, and can communicate with a UE by using a transceiver unit _B 530.

[0047] The memory unit _B540 is a functional unit for storing programs, user data, control information, etc. necessary for each operation of the gNB. The memory unit _540 may also have the function of storing control information transmitted and received between the UE, other access network devices (base station devices), core network devices, and DNs.

[0048] Furthermore, in this specification, a satellite equipped with at least the functions of a base station device may be simply referred to as a satellite or a base station device. Here, the base station device may be referred to as a base station, or may refer to a gNB, eNB, en-gNB, ng-eNB, or an access point accommodated in non-3GPP access (for example, an access point similar to that used in a wireless LAN).

[0049] [2.3. AMF / MME Device Configuration] Next, an example of the device configuration of the AMF and MME, which are part of the core network device or core network function, will be described. Here, an example of the device configuration of the AMF will be described using Figure 5. Here, the AMF will be used as an example, but it may also be read as MME. The AMF is composed of a control unit _B700, a network connection unit _B720, and a memory unit _B740. The control unit _B700, the network connection unit _B720, and the memory unit _B740 are connected via a bus. The AMF may be a node that handles the control plane.

[0050] The control unit _B700 is a functional unit that controls the operation and functions of the entire AMF. The control unit _B700 realizes various processing in the AMF by reading and executing various programs stored in the memory unit _B740 as needed.

[0051] The network connection unit _B720 is a functional unit for the AMF to connect to a base station device (gNB), and / or SMF, and / or PCF, and / or UDM, and / or SCEF, and / or NSACF in a 5G AN. In other words, the AMF can use the network connection unit _B720 to send and receive user data and / or control information between a base station device (gNB), and / or SMF, and / or PCF, and / or UDM, and / or SCEF in a 5G AN.

[0052] Explaining in detail with reference to FIG. 2, the AMF in the 5GCN can communicate with a gNB via the N2 interface by using the network connection unit _A620, can communicate with a UDM via the N8 interface, can communicate with an SMF via the N11 interface, and can communicate with a PCF via the N15 interface. The AMF can also send and receive NAS messages with a UE via the N1 interface by using the network connection unit _A620. However, since the N1 interface is logical, communication between the UE and the AMF is actually performed via a 5G AN. Furthermore, if the AMF supports the N26 interface, it can communicate with an MME via the N26 interface by using the network connection unit _A620.

[0053] The memory unit _B740 is a functional unit for storing programs, user data, control information, etc. required for each operation of the AMF. The memory unit _740 may also have the function of storing control information transmitted and received between the UE, access network devices, other core network devices, and DN.

[0054] The AMF has functions such as exchanging control messages with the RAN using the N2 interface, exchanging NAS messages with the UE using the N1 interface, encrypting and protecting the integrity of NAS messages, registration management (RM) functions, connection management (CM) functions, reachability management functions, mobility management functions for UEs, etc., transferring SM (Session Management) messages between the UE and the SMF, access authentication (Access Authorization) functions, security anchor functionality (SEA), security context management (SCM), a function to support the N2 interface for the N3IWF (Non-3GPP Interworking Function), a function to support sending and receiving NAS signals with the UE via the N3IWF, and a function to authenticate UEs connected via the N3IWF.

[0055] In addition, registration management manages the RM state for each UE. The RM state may be synchronized between the UE and the AMF. The RM state includes an unregistered state (RM-DEREGISTERED state) and a registered state (RM-REGISTERED state). In the RM-DEREGISTERED state, the UE is not registered with the network, and therefore the UE context in the AMF does not have valid location information or routing information for the UE, and therefore the AMF cannot reach the UE. In the RM-REGISTERED state, the UE is registered with the network, and therefore the UE can receive services that require registration with the network. Note that the RM state may also be expressed as a 5GMM state. In this case, the RM-DEREGISTERED state may be expressed as a 5GMM-DEREGISTERED state, and the RM-REGISTERED state may be expressed as a 5GMM-REGISTERED state.

[0056] In other words, 5GMM-REGISTERED may be a state in which each device has established a 5GMM context or a PDU session context. When each device is 5GMM-REGISTERED, UE_A10 may start transmitting and receiving user data and control messages, or may respond to paging. Furthermore, when each device is 5GMM-REGISTERED, UE_A10 may perform registration procedures other than the registration procedure for initial registration, and / or service request procedures.

[0057] Furthermore, 5GMM-DEREGISTERED may be a state in which each device has not established a 5GMM context, a state in which UE_A10's location information is not known to the network, or a state in which UE_A10 is unreachable from the network. Note that when each device is 5GMM-DEREGISTERED, UE_A10 may initiate a registration procedure or may establish a 5GMM context by performing the registration procedure.

[0058] In addition, connection management manages the CM state for each UE. The CM state may be synchronized between the UE and the AMF. The CM state includes a non-connected state (CM-IDLE state) and a connected state (CM-CONNECTED state). In the CM-IDLE state, the UE is in the RM-REGISTERED state but does not have a NAS signaling connection established with the AMF via the N1 interface. In the CM-IDLE state, the UE does not have an N2 interface connection or an N3 interface connection. On the other hand, in the CM-CONNECTED state, the UE has a NAS signaling connection established with the AMF via the N1 interface. In the CM-CONNECTED state, the UE may have an N2 interface connection and / or an N3 interface connection.

[0059] Furthermore, in connection management, the CM state in 3GPP access and the CM state in non-3GPP access may be managed separately. In this case, the CM state in 3GPP access may include a non-connected state in 3GPP access (CM-IDLE state over 3GPP access) and a connected state in 3GPP access (CM-CONNECTED state over 3GPP access). Furthermore, the CM state in non-3GPP access may include a non-connected state in non-3GPP access (CM-IDLE state over non-3GPP access) and a connected state in non-3GPP access (CM-CONNECTED state over non-3GPP access). Note that the non-connected state may be expressed as an idle mode, and the connected state mode may be expressed as a connected mode.

[0060] The CM state may be expressed as a 5GMM mode. In this case, the unconnected state may be expressed as a 5GMM-IDLE mode, and the connected state may be expressed as a 5GMM-CONNECTED mode. Furthermore, the unconnected state in 3GPP access may be expressed as a 5GMM-IDLE mode over 3GPP access, and the connected state in 3GPP access may be expressed as a 5GMM-CONNECTED mode over 3GPP access. Furthermore, the unconnected state in non-3GPP access may be expressed as 5GMM unconnected mode in non-3GPP access (5GMM-IDLE mode over non-3GPP access), and the connected state in non-3GPP access may be expressed as 5GMM connected mode in non-3GPP access (5GMM-CONNECTED mode over non-3GPP access). Note that the 5GMM unconnected mode may be expressed as idle mode, and the 5GMM connected mode may be expressed as connected mode.

[0061] In addition, one or more AMFs may be placed in the core network _B. In addition, the AMF may be a Network Function (NF) that manages one or more Network Slice Instances (NSIs). In addition, the AMF may be a Common Control Plane Network Function (CCNF) shared among multiple NSIs.

[0062] In addition, the N3IWF is a device and / or function located between the non-3GPP access and the 5GCN when the UE connects to the 5GS via the non-3GPP access.

[0063] [2.4. SMF / PGW Device Configuration] Next, an example of the device configuration of an SMF, which is part of a core network device or core network function, will be explained using Figure 5. Here, we will use the SMF as an example, but this can also be interpreted as a PGW or PGW-C. The SMF is composed of a control unit _B700, a network connection unit _B720, and a memory unit _B740. The control unit _B700, the network connection unit _B720, and the memory unit _B740 are connected via a bus. The SMF may be a node that handles the control plane.

[0064] The control unit _B700 is a functional unit that controls the operation and functions of the entire SMF. The control unit _B700 realizes various processing in the SMF by reading and executing various programs stored in the memory unit _B740 as needed.

[0065] The network connection unit _B720 is a functional unit for the SMF to connect with the AMF, and / or UPF, and / or PCF, and / or UDM. In other words, the SMF can use the network connection unit _B720 to send and receive user data and / or control information between the AMF, and / or UPF, and / or PCF, and / or UDM, and / or NSACF.

[0066] Explaining in more detail with reference to Figure 2, the SMF in the 5GCN can communicate with the AMF via the N11 interface, with the UPF via the N4 interface, with the PCF via the N7 interface, and with the UDM via the N10 interface by using the network connection unit _A620.

[0067] The memory unit _B740 is a functional unit for storing programs, user data, control information, etc. required for each operation of the SMF.

[0068] The SMF has session management functions such as establishing, modifying, and releasing PDU sessions, IP address allocation for UEs and its management, UPF selection and control, UPF configuration for routing traffic to the appropriate destination, sending and receiving the SM portion of NAS messages, Downlink Data Notification, providing AN-specific (for each AN) SM information to be sent to the AN via the N2 interface via the AMF, determining the SSC mode (Session and Service Continuity mode) for the session, and roaming functions.

[0069] In addition, the memory unit _740 may have the function of storing control information transmitted and received between the UE, access network devices, other core network devices, and DN.

[0070] [2.5. Device Configuration of UPF / PGW / SGW] Next, an example of the device configuration of the UPF, which is one of the core network devices or core network functions, will be explained using Figure 5. Here, we will explain the case of UPF as an example, but it may also be interpreted as PGW, PGW-U, or SGW. The PGW may combine the functions of both PGW-C and PGW-U. The UPF is composed of a control unit _B700, a network connection unit _B720, and a memory unit _B740. The control unit _B700, the network connection unit _B720, and the memory unit _B740 are connected via a bus. The UPF may be a node that handles the control plane.

[0071] The control unit _B700 is a functional unit that controls the operation and functions of the entire UPF. The control unit _B700 realizes various processing in the UPF by reading and executing various programs stored in the memory unit _B740 as needed.

[0072] The network connection unit _B720 is a functional unit for the UPF to connect to a base station device (gNB), and / or SMF, and / or DN within the 5G AN. In other words, the UPF can use the network connection unit _B720 to transmit and receive user data and / or control information between the base station device (gNB), and / or SMF, and / or DN within the 5G AN.

[0073] Explaining in more detail with reference to Figure 2, a UPF in a 5GCN can communicate with a gNB via the N3 interface, with an SMF via the N4 interface, with a DN via the N6 interface, and with other UPFs via the N9 interface by using the network connection unit _A620.

[0074] The memory unit _B740 is a functional unit for storing programs, user data, control information, etc. required for each operation of the UPF.

[0075] The UPF has functions such as an anchor point for intra-RAT mobility or inter-RAT mobility, an external PDU session point for interconnecting to DNs (i.e., a gateway between DNs and core network_B that forwards user data), packet routing and forwarding, an UL CL (Uplink Classifier) ​​function that supports routing of multiple traffic flows to one DN, a branching point function that supports multi-homed PDU sessions, a QoS (Quality of Service) processing function for the user plane, an uplink traffic verification function, downlink packet buffering, and a function to trigger downlink data notifications.

[0076] The UPF may also be a gateway for IP communication and / or non-IP communication. The UPF may also have a function for forwarding IP communication and a function for converting non-IP communication and IP communication. Furthermore, multiple gateways may be gateways that connect the core network_B to a single DN. The UPF may also have connectivity with other NFs and may be connected to each device via other NFs.

[0077] In addition, the memory unit _740 may have the function of storing control information transmitted and received between the UE, access network devices, other core network devices, and DN.

[0078] [2.6. Description of Other Devices and / or Functions and Identification Information in the Present Embodiment] Next, other devices and / or functions and identification information will be described.

[0079] A network refers to at least a portion of an access network _B, a core network _B, and a DN. Furthermore, one or more devices included in at least a portion of an access network _B, a core network _B, and a DN may be referred to as a network or a network device. In other words, when a network transmits, receives, and / or processes messages, it may mean that devices within the network (network devices and / or control devices) transmit, receive, receive, and / or process messages. Conversely, when a device within the network transmits, receives, receives, and / or processes messages, it may mean that the network transmits, receives, receives, and / or processes messages.

[0080] The user plane (also referred to as UP) refers to user data transmitted and received between a UE and a network. The UP may be a communication path for transmitting and receiving user data and may be composed of multiple bearers. The UP may be transmitted and received using a PDN connection in the case of 4G, or a PDU session in the case of 5G. In the case of EPS, the UP may be transmitted and received using the LTE-Uu interface, and / or the S1-U interface, and / or the S5 interface, and / or the S8 interface, and / or the SGi interface. In the case of 5GS, the UP may be transmitted and received via the interface between the UE and the NG RAN, and / or the N3 interface, and / or the N9 interface, and / or the N6 interface. The UP may also be expressed as the U-Plane.

[0081] Furthermore, a control plane (also referred to as CP) refers to a control message transmitted and received to control communication of a UE, etc. The CP may be a communication path for transmitting and receiving control messages, and may be composed of multiple bearers. The CP may be transmitted and received using a NAS (Non-Access-Stratum) signaling connection between the UE and the MME. The CP may be transmitted and received using a NAS (Non-Access-Stratum) signaling connection between the UE and the AMF. In the case of EPS, the CP may be transmitted and received using the LTE-Uu interface and the S1-MME interface. In the case of 5GS, the CP may be transmitted and received using the interface between the UE and the NG RAN and the N2 interface. The CP may be expressed as a control plane or a C-Plane.

[0082] Furthermore, the U-Plane (User Plane; UP) may be a communication path for transmitting and receiving user data and may be composed of multiple bearers. Furthermore, the C-Plane (Control Plane; CP) may be a communication path for transmitting and receiving control messages and may be composed of multiple bearers.

[0083] In addition, an MM (Mobility Management) message may be a control message transmitted and received between a UE and an AMF or an MME during an MM procedure, or may be an NAS message (also referred to as an NAS MM message).

[0084] The MM procedure (also referred to as a procedure for MM) may include a UE-initiated registration procedure, a UE- or AMF- (or network-) initiated de-registration procedure, an AMF- (or network-) initiated generic UE configuration update procedure, a UE-initiated service request procedure, an AMF- (or network-) initiated paging procedure, and an AMF- (or network-) initiated notification procedure. The MM procedure may also include a UE-initiated attach procedure, a UE- or MME- (or network-) initiated detach procedure, a UE-initiated tracking area update procedure, a UE-initiated service request procedure, and an MME- (or network-) initiated paging procedure.

[0085] In this case, in the registration procedure, the UE may send a Registration Request message to the AMF and receive a Registration Accept message or a Registration Reject message from the AMF that has received the Registration Request message. Here, the AMF may send a Registration Accept message if it approves the registration request from the UE, or may send a Registration Reject message if it does not approve the registration request.

[0086] In addition, in a de-registration procedure initiated by the UE, the UE may send a de-registration request message to the AMF and receive a de-registration accept message sent from the AMF that receives the message.

[0087] In addition, in a deregistration procedure initiated by the AMF (or network), the AMF may send a deregistration request message to the UE and receive a deregistration acceptance message sent from the UE that receives the message.

[0088] In addition, in the generic UE configuration update procedure, the AMF may send a configuration update command message to the UE and receive a configuration update complete message sent from the UE that receives the message.

[0089] In addition, in the service request procedure, the UE may send a service request message or a control plane service request message to the AMF, and may receive a service accept message or a service reject message from the AMF that has received the message. Here, the AMF may send a service accept message if it allows the request from the UE, or may send a service reject message if it does not allow the request.

[0090] In addition, in the paging procedure, the AMF sends a paging request (Request Paging) to the base station, and the base station that receives this sends a paging message to the UE, and the UE that receives this sends a service request message, or a CP service request message, or a registration request message to the AMF, which the AMF may receive.

[0091] In addition, in the notification procedure, the AMF may send a notification message to the UE and receive a notification response message, or a service request message, or a CP service request message, or a registration request message sent from the UE that received the notification message.

[0092] In the attach procedure, the UE may transmit an Attach Request message and receive an Attach Accept message or an Attach Reject message from the MME that has received the Attach Request message. Here, the MME may transmit an Attach Accept message if it accepts the request from the UE, or may transmit an Attach Reject message if it does not accept the request. In addition, when the UE receives the Attach Accept message, the UE may transmit an Attach Complete message, which the MME may receive.

[0093] In addition, in a detach procedure initiated by the UE, the UE may transmit a Detach Request message and receive a Detach Accept message transmitted from the MME that has received the Detach Request message.

[0094] In addition, in a detach procedure initiated by the MME (or the network), the MME may send a Detach Request message and receive a Detach Accept message sent from the UE that has received the Detach Request message.

[0095] In the tracking area update procedure, the UE may transmit a Tracking Area Update Request message and may receive a Tracking Area Update Accept message or a Tracking Area Update Reject message from the UE that has received the Tracking Area Update Request message. Here, the MME may transmit a Tracking Area Update Accept message if it accepts the request from the UE, or may transmit a Tracking Area Update Reject message if it does not accept the request. Furthermore, when the UE receives the Tracking Area Update Accept message, the UE may transmit a Tracking Area Update Complete message, which the MME may receive.

[0096] In addition, in the service request procedure, the UE may send a Service Request message, a Control Plane Service Request message, or an Extended Service Request message to the MME, and may receive a Service Accept message or a Service Reject message from the MME that has received the message. Here, the MME may send a Service Accept message if it approves the request from the UE, or may send a Service Reject message if it does not approve the request.

[0097] In addition, in the paging procedure, the MME transmits a paging request message to the base station, and the base station, upon receiving the paging message, transmits a paging message to the UE, and the UE, upon receiving the paging message, transmits a service request message, a CP service request message, or an extended service request message to the MME, which the MME may receive.

[0098] In addition, an SM (Session Management) message (also referred to as a NAS (Non-Access-Stratum) SM message) may be a control message transmitted and received between a UE and an SMF via an AMF during an SM procedure, or may be an NAS message (also referred to as a NAS SM message).

[0099] In addition, the SM procedure (also referred to as the procedure for SM) may include a UE-initiated PDU Session Establishment procedure, a UE- or SMF- (or network-) initiated PDU Session Modification procedure, and a UE-requested PDU Session Release procedure initiated by the UE or SMF- (or network-) initiated PDU Session Release procedure. The SM procedure may also include a UE-initiated PDN connectivity procedure, a UE-initiated PDN disconnectivity procedure, a UE-initiated bearer resource allocation procedure, a UE-initiated bearer resource modification procedure, a NW-initiated Default EPS bearer context activation procedure, a NW-initiated Dedicated EPS bearer context activation procedure, a NW-initiated EPS bearer context modification procedure, and a NW-initiated EPS bearer context deactivation procedure.

[0100] In the PDU session establishment procedure, the UE may send a PDU Session Establishment Request message to the SMF and receive a PDU Session Establishment Accept message or a PDU Session Establishment Reject message from the SMF that has received the PDU Session Establishment Request message. The SMF may send a PDU Session Establishment Accept message if it accepts the PDU session establishment request from the UE, or may send a PDU Session Establishment Reject message if it does not accept the PDU session establishment request.

[0101] In addition, in the UE-initiated PDU session modification procedure, the UE transmits a PDU Session Modification Request message to the SMF, and upon receiving the PDU Session Modification Request message, the SMF either executes the SMF-initiated PDU session modification procedure or transmits a PDU Session Modification Reject message to the UE, which the UE receives. Here, the SMF may execute the SMF-initiated PDU session modification procedure if it accepts the PDU session modification request from the UE, or transmit a PDU Session Modification Reject message if it rejects the request.

[0102] In addition, in a PDU session modification procedure initiated by the SMF (or the network), the SMF may send a PDU Session Modification Command message to the UE and receive a PDU Session Modification Complete message or a PDU Session Modification Command Reject message from the UE that has received the PDU Session Modification Command. Here, the UE may send a PDU Session Modification Complete message if it accepts the PDU session modification instruction from the SMF, or may send a PDU Session Modification Command Reject message if it does not accept it.

[0103] In addition, in the UE-initiated PDU session release procedure, the UE transmits a PDU Session Release Request message to the SMF, and upon receiving the PDU Session Release Request message, the SMF either executes the SMF-initiated PDU session release procedure or transmits a PDU Session Release Reject message to the UE, which the UE receives. Here, the SMF may execute the SMF-initiated PDU session release procedure if it accepts the PDU session release request from the UE, or may transmit a PDU Session Release Reject message if it rejects the request.

[0104] In addition, in a PDU session release procedure initiated by the SMF (or the network), the SMF may send a PDU Session Release Command message to the UE and receive a PDU Session Release Complete message from the UE that has received the PDU Session Release Command message.

[0105] In addition, in the PDN connection procedure, the UE may send a PDN Connectivity Request message to the MME, and may receive an Activate Default EPS Bearer Context Request message or a PDN Connectivity Reject message from the MME that has received the PDN Connectivity Request message. Here, the MME may send an Activate Default EPS Bearer Context Request message if it approves the request from the UE, or may send a PDN Connectivity Reject message if it does not approve the request.

[0106] In the PDN disconnection procedure, the UE may send a PDN Disconnect Request message to the MME and may receive a Deactivate EPS Bearer Context Request message or a PDN Disconnect Reject message from the MME upon receiving the PDN Disconnect Request message. Here, the MME may send a Deactivate EPS Bearer Context Request message if it approves the request from the UE, or may send a PDN Disconnect Reject message if it does not approve the request.

[0107] In the bearer resource allocation procedure, the UE may send a Bearer Resource Allocation Request message to the MME, and may receive an Activate Dedicated EPS Bearer Context Request message, a Modify EPS Bearer Context Request message, or a Bearer Resource Allocation Reject message from the MME upon receiving the message. Here, the MME may send an Activate Dedicated EPS Bearer Context Request message or a Modify EPS Bearer Context Request message if it approves the request from the UE, or may send a Bearer Resource Allocation Reject message if it does not approve the request.

[0108] In the bearer resource modification procedure, the UE may send a Bearer Resource Modification Request message to the MME, and may receive an Activate Dedicated EPS Bearer Context Request message, a Modify EPS Bearer Context Request message, a Deactivate EPS Bearer Context Request message, or a Bearer Resource Modification Reject message from the MME upon receiving the message. Here, the MME may send an Activate Dedicated EPS Bearer Context Request message, a Modify EPS Bearer Context Request message, or a Deactivate EPS Bearer Context Request message if it approves the request from the UE, or may send a Bearer Resource Modification Reject message if it does not approve the request.

[0109] In the default EPS bearer context activation procedure, the MME may send an Activate Default EPS Bearer Context Request message to the UE, and may receive an Activate Default EPS Bearer Context Accept message or an Activate Default EPS Bearer Context Reject message from the UE that has received the request. Here, the UE may send an Activate Default EPS Bearer Context Accept message if it accepts the request from the MME, or may send an Activate Default EPS Bearer Context Reject message if it does not accept the request.

[0110] In the dedicated EPS bearer context activation procedure, the MME may send an Activate Dedicated EPS Bearer Context Request message to the UE, and may receive an Activate Dedicated EPS Bearer Context Accept message or an Activate Dedicated EPS Bearer Context Reject message from the UE upon receiving the request. Here, the UE may send an Activate Dedicated EPS Bearer Context Accept message if it accepts the request from the MME, or may send an Activate Dedicated EPS Bearer Context Reject message if it does not accept the request.

[0111] In the EPS bearer context modification procedure, the MME may send a Modify EPS Bearer Context Request message to the UE, and may receive a Modify EPS Bearer Context Accept message or a Modify EPS Bearer Context Reject message from the UE that has received the message. Here, the UE may send a Modify EPS Bearer Context Accept message if it accepts the request from the MME, or may send a Modify EPS Bearer Context Reject message if it does not accept the request.

[0112] In addition, in the EPS bearer context deactivation procedure, the MME may send a Deactivate EPS Bearer Context Request message to the UE and receive a Deactivate EPS Bearer Context Accept message from the UE that has received the message.

[0113] In addition, the 5GS (5G System) service may be a connection service provided using the core network_B190. Furthermore, the 5GS service may be a service different from the EPS service or may be a service similar to the EPS service.

[0114] In addition, non-5GS services may be services other than 5GS services, and may include EPS services and / or non-EPS services.

[0115] Furthermore, the PDN (Packet Data Network) type indicates the type of PDN connection, and includes IPv4, IPv6, IPv4v6, and non-IP. If IPv4 is specified, it indicates that data will be sent and received using IPv4. If IPv6 is specified, it indicates that data will be sent and received using IPv6. If IPv4v6 is specified, it indicates that data will be sent and received using IPv4 or IPv6. If non-IP is specified, it indicates that communication will not be via IP, but via a communication method other than IP.

[0116] Furthermore, a PDU (Protocol Data Unit) session can be defined as an association between a DN that provides a PDU connectivity service and a UE, but may also be connectivity established between a UE and an external gateway. In 5GS, a UE can transmit and receive user data to and from a DN by establishing a PDU session via an access network _B and a core network _B. Here, this external gateway may be a UPF, SCEF, or the like. The UE can transmit and receive user data to and from a device such as an application server located in the DN using the PDU session.

[0117] Furthermore, an MA PDU session may be a PDU session that provides PDU connectivity services using 3GPP access and / or non-3GPP access.

[0118] Each device (UE, and / or access network device, and / or core network device) may associate one or more pieces of identification information with a PDU session and manage them. These pieces of identification information may include one or more of the DNN, QoS rule, PDU session type, application identification information, NSI identification information, and access network identification information, or may further include other information. Furthermore, when multiple PDU sessions are established, the identification information associated with the PDU sessions may be the same or different.

[0119] Furthermore, the DNN (Data Network Name) may be identification information for identifying a core network and / or an external network such as a DN. Furthermore, the DNN can also be used as information for selecting a gateway such as PGW_A30 / UPF_A235 that connects the core network B190. Furthermore, the DNN may be equivalent to an APN (Access Point Name).

[0120] Furthermore, the PDU (Protocol Data Unit / Packet Data Unit) session type indicates the type of PDU session, and can be IPv4, IPv6, Ethernet, or Unstructured. If IPv4 is specified, it indicates that data is transmitted and received using IPv4. If IPv6 is specified, it indicates that data is transmitted and received using IPv6. If Ethernet is specified, it indicates that Ethernet frames are transmitted and received. Furthermore, Ethernet may indicate that communication using IP is not performed. If Unstructured is specified, it indicates that data is transmitted and received to an application server or the like in a DN using Point-to-Point (P2P) tunneling technology. As the P2P tunneling technology, for example, UDP / IP encapsulation technology may be used. In addition to the above, the PDU session type may also include IP. IP can be specified if the UE can use both IPv4 and IPv6.

[0121] Furthermore, a PDN connection can be defined as an association between a PDN represented by an APN and a UE, but may also be connectivity established between a UE and an external gateway. By establishing a PDN connection via an access network _A and a core network _A in the EPS, the UE can transmit and receive user data to and from the PDN using the PDN connection. Here, this external gateway may be a PGW, SCEF, etc. The UE can transmit and receive user data to and from devices such as an application server located in the PDN using the PDN connection.

[0122] A PLMN (Public Land Mobile Network) is a communication network that provides mobile radio communication services. A PLMN is a network managed by an operator, which is a communications carrier, and the operator can be identified by a PLMN ID. A PLMN that matches the MCC (Mobile Country Code) and MNC (Mobile Network Code) of a UE's IMSI (International Mobile Subscriber Identity) may be a Home PLMN (HPLMN). Furthermore, a UE may store an Equivalent HPLMN list in its USIM to identify one or more Equivalent HPLMNs (EPLMNs). A PLMN different from the HPLMN and / or EPLMN may be a Visited PLMN (VPLMN). A PLMN to which a UE has successfully registered may be a Registered PLMN (RPLMN). Note that a service provided by a PLMN may be referred to as a PLMN service, and a service provided by an SNPN may be referred to as an SNPN service.

[0123] A tracking area is a single or multiple ranges managed by the core network that can be represented by the location information of UE_A10. A tracking area may be composed of multiple cells. Furthermore, a tracking area may be an area in which control messages such as paging are broadcast, or an area in which UE_A10 can move without performing a handover procedure. Furthermore, a tracking area (also referred to as a Tracking Area, TA) may be a routing area, a location area, or anything similar. A tracking area may be identified by a Tracking Area Identity (TAI) consisting of a Tracking Area Code (TAC) and a PLMN.

[0124] A registration area (also referred to as a registration area) is a set of one or more TAs assigned to a UE by the AMF. Note that while UE_A10 is moving within one or more TAs included in the registration area, it may be able to move without sending or receiving signals for tracking area update. In other words, a registration area may be a group of information indicating areas in which UE_A10 can move without performing a tracking area update procedure. A registration area may be identified by a TAI list consisting of one or more TAIs.

[0125] The UE ID is information for identifying a UE. Specifically, for example, the UE ID may be a Subscription Concealed Identifier (SUCI), a Subscription Permanent Identifier (SUPI), a Globally Unique Temporary Identifier (GUTI), an International Mobile Subscriber Identity (IMEI), an IMEISV (IMEI Software Version), or a Temporary Mobile Subscriber Identity (TMSI). Alternatively, the UE ID may be other information set in an application or a network. Furthermore, the UE ID may be information for identifying a user.

[0126] Also, a UE in single registration mode has only one active MM state. That is, a UE in single registration mode can only be active in either the RM state (5GMM state) in 5GC or the EMM state in EPC. Also, a UE in single registration mode is in 5GC NAS mode when connecting to 5GC, and is in EPC NAS mode when connecting to EPC. Also, since a UE in single registration mode can only be registered to either 5GC or EPC, when moving between EPC and 5GC, it is necessary to map EPS-GUTI (also referred to as 4G-GUTI) and 5G-GUTI.

[0127] In addition, a UE in dual registration mode may be able to independently register with 5GC and EPC. A UE in dual registration mode can independently maintain 5G-GUTI and EPS-GUTI (also referred to as 4G-GUTI).

[0128] Store and Forward (S&F) satellite operation (also referred to as S&F satellite operation mode) may refer to an operation mode in which a serving satellite provides communication services to a UE during a time period and / or geographic area without simultaneously connecting to a terrestrial network via a feeder link or an inter-satellite link (ISL). In the case of an uplink (UL), "store" may refer to storing UL information from the UE in the satellite, and "forward" may refer to forwarding the stored UL information to the terrestrial network. In the case of a downlink (DL), "store" may refer to storing DL information from the terrestrial network in the satellite, and "forward" may refer to forwarding the stored UL information to the UE. The S&F satellite operation mode may also be a mode in which there is no connectivity between either the service link, which is connectivity between the UE and the satellite, or the feeder link, which is connectivity between the satellite and the network. Note that in this specification, store and forward satellite operation may be referred to as S&F, S&F function, or S&F mode.

[0129] Normal satellite operation (also referred to as normal satellite operation mode) may be an operation mode different from the S&F satellite operation mode. Normal satellite operation may be a mode with service link connectivity and feeder link connectivity. Normal satellite operation may also be a mode without the above-mentioned store and forward functions. Normal satellite operation may also be an operation mode in which a serving satellite provides communication services to a UE for a period and / or geographic area while simultaneously connecting to a terrestrial network via a feeder link or an inter-satellite link. Normal satellite operation may also be referred to as default satellite operation (also referred to as default satellite operation mode). In this specification, normal satellite operation may also be referred to as normal mode or normal operation mode.

[0130] A serving satellite may be a satellite that provides satellite connectivity to a UE (e.g., provides a serving cell). Depending on its orbit, a serving satellite may cover a geographic area for a limited period of time. In other words, a UE with a serving satellite may be able to communicate via the satellite, while a UE without a serving satellite may not be able to communicate via the satellite. A serving satellite operating in S&F mode may have no feeder link connectivity.

[0131] UE-Satellite-UE Communication may also refer to communication between UEs within the range of one or more serving satellites, or may refer to communication between UEs using a satellite connection such that user traffic (also referred to as user data) does not pass through a terrestrial segment (e.g., including a core network).

[0132] The UE, and / or base station, and / or NW (for example, MME, or SGW, or PGW, or AMF, or SMF, or UPF, etc., the same applies below) may store information in advance and generate new information as needed. Furthermore, when such information is transmitted and received between them, the receiving party may store the received information and perform operations based on that information.

[0133] Furthermore, the UE, and / or the satellite, and / or the NW may operate in the S&F mode or in the normal mode.

[0134] Furthermore, only the UE, only the satellite, or only the NW may operate in the S&F mode and in the normal mode. For example, if only the satellite operates in the S&F mode and in the normal mode, components other than the satellite (in this case, the UE and NW) may not operate in either the S&F mode or the normal mode, and may behave in accordance with the mode in which the satellite operates. If only the UE operates in the S&F mode and in the normal mode, components other than the UE (in this case, the satellite and NW) may not operate in either the S&F mode or the normal mode, and may behave in accordance with the mode in which the UE operates. If only the NW operates in the S&F mode and in the normal mode, components other than the NW (in this case, the UE and satellite) may not operate in either the S&F mode or the normal mode, and may behave in accordance with the mode in which the NW operates.

[0135] For simplicity, the case where the UE, and / or satellite, and / or NW operates in S&F mode will be abbreviated as "operating in S&F mode (not operating in standard mode)", etc. For simplicity, the case where the UE, and / or satellite, and / or NW operates in normal mode will be abbreviated as "operating in normal mode (not operating in S&F mode)", etc.

[0136] In addition, the UE, and / or satellite, and / or NW may operate by switching between S&F mode and normal mode. For example, when the UE, and / or satellite, and / or NW is operating in normal mode, it may start a procedure and switch from normal mode to S&F mode while the procedure is being performed. In addition, when the UE, and / or satellite, and / or NW is operating in S&F mode, it may start a procedure and switch from S&F mode to normal mode while the procedure is being performed.

[0137] [3. First embodiment] First, the behavior of the UE, satellite, and NW (for example, MME, or SGW, or PGW, or AMF, or SMF, or UPF, etc., the same below) regarding the transmission of an MM message or SM message (also referred to as a first control message) or user data (also referred to as Mobile originated (MO) data, uplink data) in an MM procedure or SM procedure initiated by the UE will be described.

[0138] The UE, and / or the satellite, and / or the NW may act based on the information it knows and / or the information it has sent and received.

[0139] In this embodiment, unless otherwise specified, it is assumed that the UE, and / or satellite, and / or NW supports the S&F function or the S&F mode.

[0140] The UE may also be capable of communicating with a satellite equipped with the functionality of a base station device.

[0141] The UE may also transmit information indicating whether it supports the S&F function or the S&F mode to the satellite and / or the NW. The UE may transmit this information by including it in an NAS message and / or control information and / or a control message of a layer lower than the NAS layer (e.g., a physical layer, a MAC layer, an RLC layer, a PDCP layer, or an RRC layer). For example, the control message of the RRC layer may be RRC signaling (also referred to as an RRC message), and the control information of the RRC layer may be system information. The NAS message may also be, for example, an MM message and / or an SM message. If the UE supports the S&F function or the S&F mode, the UE may transmit information indicating that it supports the S&F function or the S&F mode to the satellite and / or the NW. By receiving this control information, the satellite and / or the NW may recognize and store whether the UE supports the S&F function or the S&F mode.

[0142] Furthermore, the satellite may transmit information indicating whether the S&F function or the S&F mode is supported to the UE and / or the NW by including it in an NAS message and / or control information and / or control message of a layer lower than the NAS layer. For example, the control message of the RRC layer may be RRC signaling (also referred to as an RRC message), and the control information of the RRC layer may be system information. Furthermore, the NAS message may be, for example, an MM message and / or an SM message. If the satellite supports the S&F function or the S&F mode, the satellite may transmit information indicating that the S&F function or the S&F mode is supported to the UE and / or the NW. By receiving this control information, the UE and / or the NW may recognize and store whether the satellite supports the S&F function or the S&F mode.

[0143] Furthermore, the NW may transmit information indicating whether the NW supports the S&F function or the S&F mode to the UE and / or the satellite by including it in control information and / or a control message of the NAS layer. For example, the control message of the NAS layer may be an MM message and / or an SM message. If the NW supports the S&F function or the S&F mode, the NW may transmit information indicating that the NW supports the S&F function or the S&F mode to the UE and / or the satellite. By receiving this control information, the UE and / or the satellite may recognize and store whether the NW supports the S&F function or the S&F mode.

[0144] The satellite may transmit information indicating whether it is operating in the S&F mode, information indicating whether a service link is available, information indicating whether a feeder link is available, information indicating whether it is operating in the normal mode, information indicating the time and / or period for applying the S&F mode (canceling the normal mode), and / or information indicating the time and / or period for canceling the S&F mode (applying the normal mode) to the UE and / or the NW in an NAS message and / or control information and / or control messages of a layer lower than the NAS layer (e.g., a physical layer, a MAC layer, an RLC layer, a PDCP layer, an RRC layer). For example, the control message of the RRC layer may be an RRC message, and the control information of the RRC layer may be system information. The NAS message may be, for example, an MM message and / or an SM message. These pieces of information may be transmitted periodically or whenever an event occurs. Here, the event may be, for example, a change in mode (when the S&F mode is changed or when the normal mode is changed), a change in the status of the service link (when the service link becomes available or unavailable), a change in the status of the feeder link (when the feeder link becomes available or unavailable), etc. Here, the satellite may determine whether to transmit at least a portion of this information to the UE based on information received from the UE and / or the NW indicating whether the S&F function or the S&F mode is supported. For example, when receiving information indicating that the UE and / or the NW supports the S&F function or the S&F mode, the satellite determines whether to transmit at least a portion of this information to the UE. If the satellite determines to transmit this information, it may transmit it to the UE and / or the NW, or if the satellite determines not to transmit this information, it may not transmit it to the UE and / or the NW. Furthermore, if at least a portion of this information has not yet been transmitted to the UE and / or the NW or if at least a portion of this information has been updated, the satellite may determine to transmit it to the UE and / or the NW.In addition, if at least some of this information has already been transmitted to the UE and / or NW, or if the transmitted information has not been updated, it may be decided not to transmit it to the UE and / or NW.

[0145] Furthermore, information indicating whether or not the device is operating in S&F mode may be interpreted as information indicating whether or not the device is operating in S&F mode, or information indicating whether or not the device is operating in S&F mode. Furthermore, information indicating whether or not the service link is available (also referred to as whether or not there is service link connectivity) may be interpreted as information indicating whether or not the service link is available (also referred to as whether or not there is service link connectivity) or information indicating whether or not the service link is unavailable (also referred to as no service link connectivity). Furthermore, information indicating whether or not the feeder link is available (also referred to as whether or not there is feeder link connectivity) may be interpreted as information indicating whether or not the feeder link is available (also referred to as whether or not there is feeder link connectivity) or information indicating whether or not the feeder link is unavailable (also referred to as no feeder link connectivity). Furthermore, information indicating whether or not the device is operating in normal mode may be interpreted as information indicating whether or not the device is operating in normal mode, or information indicating whether or not the device is operating in normal mode.

[0146] For example, when a satellite is operating in S&F mode, the satellite may transmit information indicating that the satellite is operating in S&F mode and / or information indicating that the satellite is not operating in normal mode to the UE and / or NW. The UE and / or NW may recognize and store that the satellite is operating in S&F mode and / or not operating in normal mode by receiving at least one of these pieces of control information.

[0147] Furthermore, when the satellite is operating in the normal mode, the satellite may transmit information indicating that it is operating in the normal mode and / or information indicating that it is not operating in the S&F mode to the UE and / or the NW. By receiving at least one of these pieces of control information, the UE and / or the NW may recognize and store that it is not operating in the S&F mode and / or that it is operating in the normal mode.

[0148] Furthermore, when the satellite is operating in the S&F mode, and the service link is available but the feeder link is not available, the satellite may transmit to the UE information indicating that it is operating in the S&F mode, and / or information indicating that it is not operating in the normal mode, and / or information indicating that the service link is available, and / or information indicating that the feeder link is not available. By receiving at least one of these pieces of control information, the UE and / or the NW may recognize and store that it is operating in the S&F mode, and / or information indicating that it is not operating in the normal mode, and / or information indicating that the service link is available, and / or information indicating that the feeder link is not available.

[0149] Furthermore, when the satellite is operating in the S&F mode, the service link is unavailable, and the feeder link is available, the satellite may transmit to the NW information indicating that the satellite is operating in the S&F mode, and / or information indicating that the satellite is not operating in the normal mode, and / or information indicating that the service link is unavailable, and / or information indicating that the feeder link is available. By receiving at least one of these pieces of control information, the UE and / or the NW may recognize and store that the satellite is operating in the S&F mode, and / or information indicating that the satellite is not operating in the normal mode, and / or information indicating that the service link is unavailable, and / or information indicating that the feeder link is available.

[0150] Furthermore, when the satellite is operating in the normal mode, the satellite may transmit to the UE and / or the NW information indicating that it is operating in the normal mode, and / or information indicating that it is not operating in the S&F mode, and / or information indicating that the service link is available, and / or information indicating that the feeder link is available. By receiving at least one of these pieces of control information, the UE and / or the NW may recognize and store that it is not operating in the S&F mode, and / or operating in the normal mode, and / or that the service link is available, and / or the feeder link is available.

[0151] The satellite may also transmit, to the UE and / or NW, information indicating the time and / or period for applying the S&F mode (canceling the application of the normal mode), and / or information indicating the time and / or period for canceling the application of the S&F mode (applying the normal mode).

[0152] For example, when a satellite operating in the normal mode intends to operate in the S&F mode, it may transmit information indicating the time and / or period for applying the S&F mode (canceling the application of the normal mode). By receiving at least one of these pieces of control information, the UE and / or NW may recognize and store the time and / or period for applying the S&F mode and / or canceling the application of the normal mode and / or applying the S&F mode.

[0153] Furthermore, when a satellite operating in the S&F mode intends to operate in the normal mode, it may transmit information indicating the time and / or period for canceling the application of the S&F mode (applying the normal mode). By receiving at least one of these pieces of control information, the UE and / or NW may recognize and store the time and / or period for canceling the application of the S&F mode and / or applying the normal mode and / or applying the normal mode.

[0154] In addition, a UE and / or NW operating in normal mode may recognize and store that it is operating in normal mode if it does not receive information indicating that it is operating in S&F mode and / or information indicating that it is not operating in normal mode.

[0155] In addition, a UE and / or NW operating in S&F mode may recognize and store that it is operating in S&F mode if it does not receive information indicating that it is not operating in S&F mode and / or information indicating that it is operating in normal mode.

[0156] Furthermore, if a UE and / or NW operating in normal mode does not receive information indicating that the service link is unavailable or information indicating that the feeder link is unavailable, the UE and / or NW may recognize that it is operating in normal mode, store this information, and behave in normal mode.

[0157] Furthermore, if a UE and / or NW operating in S&F mode does not receive information indicating that a service link is available and information indicating that a feeder link is available, the UE and / or NW may recognize that it is operating in S&F mode, memorize this, and behave in S&F mode.

[0158] Additionally, when operating in normal mode, the UE, and / or the satellite, and / or the NW may transmit and receive control messages (e.g., MM messages and / or SM messages) and user data.

[0159] Furthermore, information indicating whether or not the device is operating in the S&F mode, and / or information indicating whether or not a service link is available, and / or information indicating whether or not a feeder link is available, and / or information indicating whether or not the device is operating in the normal mode, and / or information indicating the time and / or period for applying the S&F mode, and / or information indicating the time and / or period for canceling the application of the S&F mode may be included in and transmitted / received in the first to eighth control messages described below, or may be included in and transmitted / received in a control message different from the first to eighth control messages described below. For example, the information may be included in and transmitted / received in a control message different from the first to eighth control messages described below before transmitting / receiving the first control message. For example, the information may be included in and transmitted / received in a control message different from the first to eighth control messages described below after transmitting / receiving the first control message and before transmitting / receiving the eighth control message. For example, the information may be included in and transmitted / received in a control message different from the first to eighth control messages described below after transmitting / receiving the eighth control message.

[0160] Furthermore, when the UE is operating in S&F mode (when the service link is not available but the feeder link is available), the UE does not need to transmit MM messages or SM messages (also referred to as first control messages) or user data (Mobile originated (MO) data, also referred to as uplink data) in the MM procedure or SM procedure initiated by the UE to the NW via the satellite.

[0161] In addition, when the UE is operating in S&F mode (when the service link is available but the feeder link is not available), the UE may not transmit the first control message or user data to the NW via the satellite.

[0162] Furthermore, when the UE is operating in the S&F mode (when the service link is available but the feeder link is not), or when the UE is operating in the normal mode, the UE may transmit a first control message or user data to the NW via the satellite. The UE may start a timer (also referred to as a first timer) based on the transmission of the first control message or user data.

[0163] Furthermore, when the UE operates in the S&F mode (when the service link is available but the feeder link is not available), if the UE transmits a first control message or user data to the NW via the satellite, the satellite may transmit, in response to the received first control message or user data, a control message (also referred to as a second control message) including information indicating that the first control message or user data could not be transferred and / or information indicating that the first control message or user data cannot be transferred because the feeder link is not available, to the UE. The second control message may be, for example, a control message of a layer lower than the NAS layer (e.g., a physical layer, a MAC layer, an RLC layer, a PDCP layer, or an RRC layer), or may be a control message of the NAS layer (a NAS message). Furthermore, based on receiving the second control message and / or the control information contained in the second control message, the UE may recognize that the MM procedure or SM procedure initiated by the UE has been rejected, or may stop a second timer that was running in the UE, or may recognize that the first control message or user data has not been transferred to the NW, or may retransmit the first control message or user data immediately or after waiting for a predetermined period (also referred to as a second predetermined period), or may perform retransmission of the same procedure or user data after waiting for the second predetermined period, or may perform retransmission of the same procedure or user data when switching to operation in normal mode, or may perform retransmission of the same procedure or user data while operating in S&F mode and when a feeder link becomes available.

[0164] Furthermore, when the UE operates in the S&F mode (when the service link is available but the feeder link is not), and the UE transmits a first control message or user data to the NW via the satellite, the satellite may store the received first control message or user data for a predetermined period (also referred to as a first predetermined period). In this case, the satellite may transmit to the UE a control message (also referred to as a third control message) including information indicating that the feeder link is not available, and / or information indicating that the first control message or user data has been stored, and / or information indicating that the first control message or user data has been stored because the feeder link is not available, and / or the first predetermined period (i.e., the storage period). The third control message may be, for example, a control message of a layer lower than the NAS layer (e.g., a physical layer, a MAC layer, an RLC layer, a PDCP layer, or an RRC layer), or may be an NAS message. The first predetermined period may be included in the third control message as a timer value. Furthermore, the UE may recognize information indicating that the feeder link is unavailable, information indicating that the first control message or user data has been stored, information indicating that the first control message or user data has been stored because the feeder link is unavailable, and / or a first predetermined period, etc., based on reception of the third control message and / or the control information included in the third control message. The first predetermined period may be a period predetermined by a standard or may be a period dependent on the implementation of the satellite. Furthermore, the UE may start a timer (also referred to as a second timer) based on reception of the third control message and / or the control information included in the third control message. In this case, the UE may start the second timer using the first predetermined period (or timer value) received from the satellite. The satellite may start the timer (also referred to as a third timer) based on transmission of the third control message and / or the control information included in the third control message and / or storage of the first control message or user data.At this time, the satellite may start a third timer using the first predetermined period (or timer value) transmitted to the UE. Note that the third control message and / or at least one piece of control information included in the third control message may be referred to as a store indication or an AS (Access Stratum) indication.

[0165] Furthermore, when the feeder link does not become available within the first predetermined period, the satellite may discard or delete the first control message and / or the control information or user data included in the first control message received from the UE and stored, and may transmit a second control message to the UE in response to the received first control message or user data. Note that the satellite may manage the first predetermined period using a timer (third timer). That is, "when the feeder link does not become available within the first predetermined period" may be read as "when the feeder link does not become available during the period from when the third timer using the first predetermined period is started until the third timer expires." Furthermore, if the UE receives the second control message and / or the control information contained in the second control message before the second timer expires, the UE may recognize that the MM procedure or SM procedure initiated by the UE has been rejected, or may stop the second timer that was running in the UE, or may recognize that the first control message or user data has not been transferred to the NW, or may retransmit the first control message or user data immediately or after waiting for a predetermined period (also referred to as a second predetermined period), or may perform retransmission of the same procedure or user data after waiting for the second predetermined period, or may perform retransmission of the same procedure or user data when switching to operation in normal mode, or may perform retransmission of the same procedure or user data while operating in S&F mode and when a feeder link becomes available.

[0166] Furthermore, when the feeder link becomes available within the first predetermined period, the satellite may transmit (i.e., transfer) to the NW the first control message and / or the control information or user data included in the first control message that it has received from the UE and stored. In this case, the satellite may transmit to the UE a control message (also referred to as a fourth control message) including information indicating that the first control message or user data has been transferred because the feeder link has become available, or information indicating that the stored first control message or user data has been transferred. The fourth control message may be, for example, a control message of a layer lower than the NAS layer (e.g., a physical layer, a MAC layer, an RLC layer, a PDCP layer, or an RRC layer), or may be an NAS message. Note that the satellite may manage the first predetermined period using a timer (a third timer). That is, "when the feeder link becomes available within the first predetermined period" may be read as "when the feeder link becomes available during the period from the start of the third timer using the first predetermined period until the expiration of the third timer." The fourth control message or at least one piece of control information included in the fourth control message may be referred to as a forward indication or an AS (Access Stratum) indication. Furthermore, based on reception of the fourth control message and / or the control information included in the fourth control message, the UE may stop a second timer that has been running in the UE, or may recognize that the first control message or user data has been forwarded to the NW, or may recognize that there is no need to retransmit the first control message or user data. Furthermore, based on transmission of the fourth control message and / or the control information included in the fourth control message, the satellite may stop a third timer that has been running in the satellite. Note that, "when the feeder link becomes available" may mean when operation is switched to normal mode, or when the feeder link becomes available while operating in S&F mode.

[0167] Furthermore, if the UE does not receive a fourth control message from the satellite before the second timer that is operating expires, the UE may recognize that the MM procedure or SM procedure that it initiated has been rejected, or may stop the second timer that was operating, or may recognize that the first control message or user data has not been transferred to the NW, or may retransmit the first control message or user data immediately or after waiting for a second predetermined period, or may perform retransmission of the same procedure or user data after waiting for a second predetermined period, or may perform retransmission of the same procedure or user data when switching to operation in normal mode, or may perform retransmission of the same procedure or user data while operating in S&F mode and when a feeder link becomes available.

[0168] When the UE starts the second timer, the UE may suspend the first timer that is running, and when the UE stops the second timer or when the second timer expires, the UE may resume counting the suspended first timer.

[0169] The NW may also receive a first control message or user data in an MM procedure or SM procedure initiated by the UE from the satellite.

[0170] Furthermore, in an MM procedure or SM procedure initiated by the UE, after receiving a first control message from a satellite, when the NW is operating in S&F mode (when the service link is available but the feeder link is not available), the NW does not need to send an MM message or SM message (also referred to as a fifth control message) to the UE via the satellite in response to the first control message.

[0171] Furthermore, in an MM procedure or SM procedure initiated by the UE, after receiving a first control message from a satellite, when the NW is operating in S&F mode (when the service link is not available but the feeder link is available), the NW may not need to transmit a fifth control message to the UE via the satellite in response to the first control message.

[0172] In addition, after receiving a first control message from the satellite in an MM procedure or SM procedure initiated by the UE, the NW may transmit a fifth control message to the UE via the satellite in response to the first control message when operating in S&F mode (when the service link is not available but the feeder link is available) or when operating in normal mode.

[0173] Furthermore, when the NW operates in the S&F mode (when the service link is unavailable but the feeder link is available), if the NW transmits the fifth control message to the UE via the satellite, the satellite may transmit, in response to the received fifth control message, a control message (also referred to as a sixth control message) including information indicating that the fifth control message could not be forwarded and / or information indicating that the fifth control message cannot be forwarded because the service link is unavailable, to the NW. The sixth control message may be, for example, a control message of the NAS layer (NAS message). Furthermore, based on receiving the sixth control message and / or the control information contained in the sixth control message, the NW may recognize that the MM procedure or SM procedure initiated by the UE has been rejected, may stop the fourth timer that was running in the NW, may recognize that the fifth control message was not forwarded to the UE, may resend the fifth control message immediately or after waiting a predetermined period (also referred to as the fourth predetermined period), may resend the fifth control message when switching to operation in normal mode, or may resend the fifth control message while operating in S&F mode when a service link becomes available.

[0174] Furthermore, when the NW operates in the S&F mode (when the service link is unavailable but the feeder link is available), and transmits the fifth control message to the UE via the satellite, the satellite may store the received fifth control message for a predetermined period (also referred to as a third predetermined period). In this case, the satellite may transmit to the NW a control message (also referred to as a seventh control message) including information indicating that the service link is unavailable, and / or information indicating that the fifth control message has been stored, and / or information indicating that the fifth control message has been stored because the service link is unavailable, and / or the third predetermined period (i.e., the storage period). The seventh control message may be, for example, an NAS message. The third predetermined period may be included in the seventh control message as a timer value. Furthermore, the NW may recognize information indicating that the service link is unavailable, information indicating that the seventh control message has been stored, information indicating that the seventh control message has been stored because the service link is unavailable, and / or a third predetermined period, etc., based on reception of the seventh control message and / or the control information included in the seventh control message. The third predetermined period may be a period predetermined by a standard or may be a period dependent on the implementation of the satellite. Furthermore, the NW may start a timer (also referred to as a fourth timer) based on reception of the seventh control message and / or the control information included in the seventh control message. At this time, the NW may start the fourth timer using the third predetermined period (or timer value) received from the satellite. Furthermore, the satellite may start a timer (also referred to as a fifth timer) based on transmission of the seventh control message and / or the control information included in the seventh control message and / or storage of the fifth control message. At this time, the satellite may start the fifth timer using the third predetermined period (or timer value) transmitted to the NW. The seventh control message and / or at least one piece of control information included in the seventh control message may be referred to as a store indication or an AS (Access Stratum) indication.

[0175] Furthermore, when the service link does not become available within the third predetermined period, the satellite may discard or delete the fifth control message and / or the control information included in the fifth control message received from the NW and stored, and may transmit a sixth control message to the NW in response to the received fifth control message. The satellite may manage the third predetermined period using a timer (fifth timer). That is, "when the service link does not become available within the third predetermined period" may be read as "when the service link does not become available between the start of the fifth timer using the third predetermined period and the expiration of the fifth timer." Furthermore, based on receiving the sixth control message and / or the control information contained in the sixth control message, the NW may recognize that the MM procedure or SM procedure initiated by the UE has been rejected, may stop the fourth timer that was running in the NW, may recognize that the fifth control message was not forwarded to the UE, may resend the fifth control message immediately or after waiting a predetermined period (also referred to as the fourth predetermined period), may resend the fifth control message when switching to operation in normal mode, or may resend the fifth control message while operating in S&F mode when a service link becomes available.

[0176] Furthermore, when the service link becomes available within the third predetermined period, the satellite may transmit (i.e., forward) to the UE the fifth control message and / or the control information included in the fifth control message that it received from the NW and stored. In this case, the satellite may transmit to the NW a control message (also referred to as an eighth control message) including information indicating that the fifth control message has been forwarded because the service link has become available, or information indicating that the stored fifth control message has been forwarded. The eighth control message may be, for example, an NAS message. The satellite may manage the third predetermined period using a timer (fifth timer). That is, "when the service link becomes available within the third predetermined period" may be read as "when the service link becomes available between the start of the fifth timer using the third predetermined period and the expiration of the fifth timer." The eighth control message or at least one piece of control information included in the eighth control message may be referred to as a forward indication or an AS (Access Stratum) indication. Furthermore, the NW may stop a fourth timer that has been running in the NW based on reception of the eighth control message and / or the control information included in the eighth control message, or may recognize that the fifth control message has been forwarded to the UE, or may recognize that there is no need to retransmit the fifth control message. Furthermore, the satellite may stop a fifth timer that has been running in the satellite based on transmission of the eighth control message and / or the control information included in the eighth control message. Note that when the service link becomes available may mean when operation is switched to normal mode, or when the service link becomes available while operating in S&F mode.

[0177] Furthermore, if the NW does not receive the eighth control message from the satellite before the fourth timer that is currently operating expires, the NW may recognize that the MM procedure or SM procedure initiated by the UE has been rejected, or may stop the fourth timer that was currently operating in the NW, or may recognize that the fifth control message was not forwarded to the UE, or may resend the fifth control message immediately or after waiting for a fourth predetermined period of time, or may resend the fifth control message when switching to operation in normal mode, or may resend the fifth control message while operating in S&F mode and when a service link becomes available.

[0178] Furthermore, if the UE receives a fifth control message from the NW via the satellite before the first timer that is running expires, the UE may recognize that the MM procedure or SM procedure initiated by the UE has been completed successfully.

[0179] Furthermore, the UE may recognize that the MM procedure or SM procedure initiated by the UE has been successfully completed if it does not receive a fifth control message from the NW via the satellite before the first timer that is running expires.

[0180] The first control message may be a registration request message, and the fifth control message may be a registration accept message or a registration reject message. In this case, the first timer may be a T3510 timer.

[0181] Alternatively, the first control message may be a non-registration request message and the fifth control message may be a non-registration accept message, in which case the first timer may be a T3521 timer.

[0182] Alternatively, the first control message may be a non-registration request message, and the fifth control message may not exist. In this case, the first timer may not exist.

[0183] Alternatively, the first control message may be a service request message or a CP service request message, and the fifth control message may be a service accept message or a service reject message. In this case, the first timer may be a T3517 timer.

[0184] Alternatively, the first control message may be an uplink (UL) NAS transport message, and the fifth control message may not exist. In this case, the first timer may not exist.

[0185] In addition, the first control message may be a PDU session establishment request message, and the fifth control message may be a PDU session establishment acceptance message or a PDU session establishment rejection message. In this case, the first timer may be a T3580 timer.

[0186] In addition, the first control message may be a PDU session change request message, and the fifth control message may be a PDU session change command message or a PDU session change rejection message. In this case, the first timer may be a T3581 timer.

[0187] In addition, the first control message may be a PDU session release request message, and the fifth control message may be a PDU session release command message or a PDU session release rejection message. In this case, the first timer may be a T3582 timer.

[0188] Alternatively, the first control message may be an attach request message, and the fifth control message may be an attach accept message or an attach reject message. In this case, the first timer may be T3410.

[0189] Alternatively, the first control message may be a detach request message, and the fifth control message may not exist. In this case, the first timer may not exist.

[0190] Alternatively, the first control message may be a detach request message and the fifth control message may be a detach accept message, in which case the first timer may be T3421.

[0191] Alternatively, the first control message may be a tracking area update request message, and the fifth control message may be a tracking area update accept message or a tracking area update reject message. In this case, the first timer may be T3430.

[0192] Alternatively, the first control message may be a service request message, a CP service request message, or an extended service request message, and the fifth control message may be a service accept message or a service reject message. In this case, the first timer may be T3417.

[0193] Alternatively, the first control message may be a PDN connectivity request message, and the fifth control message may be an activate default EPS bearer context request message or a PDN connectivity reject message. In this case, the first timer may be T3482.

[0194] Alternatively, the first control message may be a PDN deconnection request message, and the fifth control message may be a Deactivate EPS Bearer Context Request message or a PDN deconnection reject message. In this case, the first timer may be T3492.

[0195] Alternatively, the first control message may be a bearer resource allocation request message, and the fifth control message may be an activate dedicated EPS bearer context request message, a modify EPS bearer context request message, or a bearer resource allocation reject message, in which case the first timer may be T3480.

[0196] Alternatively, the first control message may be a Modify Bearer Resources Request message, and the fifth control message may be an Activate Dedicated EPS Bearer Context Request message, a Modify EPS Bearer Context Request message, a Deactivate EPS Bearer Context Request message, or a Modify Bearer Resources Reject message. In this case, the first timer may be T3481.

[0197] Alternatively, the UE may extend the first timer instead of starting the second timer when it receives the second control message from the satellite. For example, the UE may extend the first timer indefinitely or for a certain period of time until it receives the fifth control message.

[0198] Furthermore, the first to eighth control messages may include not only control information but also user data.

[0199] In addition, the above-mentioned behaviors of the UE, satellite, and NW operating in S&F mode can also be applied when attempting to operate in normal mode or when switching to operation in normal mode before or during the execution of the above-mentioned procedures or transmission of user data.

[0200] In addition, the above-mentioned behaviors of the UE, satellite, and NW operating in normal mode can also be applied when attempting to operate in S&F mode or when switching to operation in S&F mode before or during the execution of the above-mentioned procedures or transmission of user data.

[0201] It should be noted that the above may be applied not only to PLMNs but also to NPNs (SNPNs and / or PNI-NPNs).

[0202] Furthermore, the above may be applied only to 3GPP access, or only to non-3GPP access, or may be applied to both 3GPP access and non-3GPP access.

[0203] Note that this embodiment may be executed multiple times, or the second embodiment may be executed one or more times after the present embodiment is executed one or more times, or the second embodiment may be executed one or more times after the present embodiment is executed one or more times.

[0204] [4. Second embodiment] Next, the behavior of the UE, satellite, and NW (for example, MME, or AMF, or SMF, or UPF, etc., the same below) regarding the transmission of an MM message or SM message (also referred to as a first control message) or user data (Mobile terminated (MT) data, also referred to as downlink data) in an MM procedure or SM procedure initiated by the NW will be described.

[0205] In this embodiment, unless otherwise specified, it is assumed that the UE, and / or satellite, and / or NW supports the S&F function or the S&F mode.

[0206] The UE may also be capable of communicating with a satellite equipped with the functionality of a base station device.

[0207] The UE, and / or the satellite, and / or the NW may act based on the information it knows and / or the information it has sent and received.

[0208] The UE may also transmit information indicating whether it supports the S&F function or the S&F mode to the satellite and / or the NW. The UE may transmit this information by including it in an NAS message and / or control information and / or a control message of a layer lower than the NAS layer (e.g., a physical layer, a MAC layer, an RLC layer, a PDCP layer, or an RRC layer). For example, the control message of the RRC layer may be RRC signaling (also referred to as an RRC message), and the control information of the RRC layer may be system information. The NAS message may also be, for example, an MM message and / or an SM message. If the UE supports the S&F function or the S&F mode, the UE may transmit information indicating that it supports the S&F function or the S&F mode to the satellite and / or the NW. By receiving this control information, the satellite and / or the NW may recognize and store whether the UE supports the S&F function or the S&F mode.

[0209] Furthermore, the satellite may transmit information indicating whether the S&F function or the S&F mode is supported to the UE and / or the NW by including it in an NAS message and / or control information and / or control message of a layer lower than the NAS layer. For example, the control message of the RRC layer may be RRC signaling (also referred to as an RRC message), and the control information of the RRC layer may be system information. Furthermore, the NAS message may be, for example, an MM message and / or an SM message. If the satellite supports the S&F function or the S&F mode, the satellite may transmit information indicating that the S&F function or the S&F mode is supported to the UE and / or the NW. By receiving this control information, the UE and / or the NW may recognize and store whether the satellite supports the S&F function or the S&F mode.

[0210] Furthermore, the NW may transmit information indicating whether the NW supports the S&F function or the S&F mode to the UE and / or the satellite by including it in control information and / or a control message of the NAS layer. For example, the control message of the NAS layer may be an MM message and / or an SM message. If the NW supports the S&F function or the S&F mode, the NW may transmit information indicating that the NW supports the S&F function or the S&F mode to the UE and / or the satellite. By receiving this control information, the UE and / or the satellite may recognize and store whether the NW supports the S&F function or the S&F mode.

[0211] The satellite may transmit information indicating whether it is operating in the S&F mode, information indicating whether a service link is available, information indicating whether a feeder link is available, information indicating whether it is operating in the normal mode, information indicating the time and / or period for applying the S&F mode (canceling the normal mode), and / or information indicating the time and / or period for canceling the S&F mode (applying the normal mode) to the UE and / or the NW in an NAS message and / or control information and / or control messages of a layer lower than the NAS layer (e.g., a physical layer, a MAC layer, an RLC layer, a PDCP layer, an RRC layer). For example, the control message of the RRC layer may be an RRC message, and the control information of the RRC layer may be system information. The NAS message may be, for example, an MM message and / or an SM message. These pieces of information may be transmitted periodically or whenever an event occurs. Here, the event may be, for example, a change in mode (when the S&F mode is changed or when the normal mode is changed), a change in the status of the service link (when the service link becomes available or unavailable), a change in the status of the feeder link (when the feeder link becomes available or unavailable), etc. Here, the satellite may determine whether to transmit at least a portion of this information to the UE based on information received from the UE and / or the NW indicating whether the S&F function or the S&F mode is supported. For example, when receiving information indicating that the UE and / or the NW supports the S&F function or the S&F mode, the satellite determines whether to transmit at least a portion of this information to the UE. If the satellite determines to transmit this information, it may transmit it to the UE and / or the NW, or if the satellite determines not to transmit this information, it may not transmit it to the UE and / or the NW. Furthermore, if at least a portion of this information has not yet been transmitted to the UE and / or the NW or if at least a portion of this information has been updated, the satellite may determine to transmit it to the UE and / or the NW.In addition, if at least some of this information has already been transmitted to the UE and / or NW, or if the transmitted information has not been updated, it may be decided not to transmit it to the UE and / or NW.

[0212] Furthermore, information indicating whether or not the device is operating in S&F mode may be interpreted as information indicating whether or not the device is operating in S&F mode, or information indicating whether or not the device is operating in S&F mode. Furthermore, information indicating whether or not the service link is available (also referred to as whether or not there is service link connectivity) may be interpreted as information indicating whether or not the service link is available (also referred to as whether or not there is service link connectivity) or information indicating whether or not the service link is unavailable (also referred to as no service link connectivity). Furthermore, information indicating whether or not the feeder link is available (also referred to as whether or not there is feeder link connectivity) may be interpreted as information indicating whether or not the feeder link is available (also referred to as whether or not there is feeder link connectivity) or information indicating whether or not the feeder link is unavailable (also referred to as no feeder link connectivity). Furthermore, information indicating whether or not the device is operating in normal mode may be interpreted as information indicating whether or not the device is operating in normal mode, or information indicating whether or not the device is operating in normal mode.

[0213] For example, when a satellite is operating in S&F mode, the satellite may transmit information indicating that the satellite is operating in S&F mode and / or information indicating that the satellite is not operating in normal mode to the UE and / or NW. The UE and / or NW may recognize and store that the satellite is operating in S&F mode and / or not operating in normal mode by receiving at least one of these pieces of control information.

[0214] Furthermore, when the satellite is operating in the normal mode, the satellite may transmit information indicating that it is operating in the normal mode and / or information indicating that it is not operating in the S&F mode to the UE and / or the NW. By receiving at least one of these pieces of control information, the UE and / or the NW may recognize and store that it is not operating in the S&F mode and / or that it is operating in the normal mode.

[0215] Furthermore, when the satellite is operating in the S&F mode, and the service link is available but the feeder link is not available, the satellite may transmit to the UE information indicating that it is operating in the S&F mode, and / or information indicating that it is not operating in the normal mode, and / or information indicating that the service link is available, and / or information indicating that the feeder link is not available. By receiving at least one of these pieces of control information, the UE and / or the NW may recognize and store that it is operating in the S&F mode, and / or information indicating that it is not operating in the normal mode, and / or information indicating that the service link is available, and / or information indicating that the feeder link is not available.

[0216] Furthermore, when the satellite is operating in the S&F mode, the service link is unavailable, and the feeder link is available, the satellite may transmit to the NW information indicating that the satellite is operating in the S&F mode, and / or information indicating that the satellite is not operating in the normal mode, and / or information indicating that the service link is unavailable, and / or information indicating that the feeder link is available. By receiving at least one of these pieces of control information, the UE and / or the NW may recognize and store that the satellite is operating in the S&F mode, and / or information indicating that the satellite is not operating in the normal mode, and / or information indicating that the service link is unavailable, and / or information indicating that the feeder link is available.

[0217] Furthermore, when the satellite is operating in the normal mode, the satellite may transmit to the UE and / or the NW information indicating that it is operating in the normal mode, and / or information indicating that it is not operating in the S&F mode, and / or information indicating that the service link is available, and / or information indicating that the feeder link is available. By receiving at least one of these pieces of control information, the UE and / or the NW may recognize and store that it is not operating in the S&F mode, and / or operating in the normal mode, and / or that the service link is available, and / or the feeder link is available.

[0218] The satellite may also transmit, to the UE and / or NW, information indicating the time and / or period for applying the S&F mode (canceling the application of the normal mode), and / or information indicating the time and / or period for canceling the application of the S&F mode (applying the normal mode).

[0219] For example, when a satellite operating in the normal mode intends to operate in the S&F mode, it may transmit information indicating the time and / or period for applying the S&F mode (canceling the application of the normal mode). By receiving at least one of these pieces of control information, the UE and / or NW may recognize and store the time and / or period for applying the S&F mode and / or canceling the application of the normal mode and / or applying the S&F mode.

[0220] Furthermore, when a satellite operating in the S&F mode intends to operate in the normal mode, it may transmit information indicating the time and / or period for canceling the application of the S&F mode (applying the normal mode). By receiving at least one of these pieces of control information, the UE and / or NW may recognize and store the time and / or period for canceling the application of the S&F mode and / or applying the normal mode and / or applying the normal mode.

[0221] In addition, a UE and / or NW operating in normal mode may recognize and store that it is operating in normal mode if it does not receive information indicating that it is operating in S&F mode and / or information indicating that it is not operating in normal mode.

[0222] In addition, a UE and / or NW operating in S&F mode may recognize and store that it is operating in S&F mode if it does not receive information indicating that it is not operating in S&F mode and / or information indicating that it is operating in normal mode.

[0223] Furthermore, if a UE and / or NW operating in normal mode does not receive information indicating that the service link is unavailable or information indicating that the feeder link is unavailable, the UE and / or NW may recognize that it is operating in normal mode, store this information, and behave in normal mode.

[0224] Furthermore, if a UE and / or NW operating in S&F mode does not receive information indicating that a service link is available and information indicating that a feeder link is available, the UE and / or NW may recognize that it is operating in S&F mode, memorize this, and behave in S&F mode.

[0225] Furthermore, information indicating whether or not the device is operating in the S&F mode, and / or information indicating whether or not a service link is available, and / or information indicating whether or not a feeder link is available, and / or information indicating whether or not the device is operating in the normal mode, and / or information indicating the time and / or period for applying the S&F mode, and / or information indicating the time and / or period for canceling the application of the S&F mode may be included in and transmitted / received in the first to eighth control messages described below, or may be included in and transmitted / received in a control message different from the first to eighth control messages described below. For example, the information may be included in and transmitted / received in a control message different from the first to eighth control messages described below before transmitting / receiving the first control message. For example, the information may be included in and transmitted / received in a control message different from the first to eighth control messages described below after transmitting / receiving the first control message and before transmitting / receiving the eighth control message. For example, the information may be included in and transmitted / received in a control message different from the first to eighth control messages described below after transmitting / receiving the eighth control message.

[0226] Furthermore, when the network is operating in S&F mode (when the service link is available but the feeder link is not available), the network does not need to transmit an MM message or an SM message (also referred to as a first control message) or user data (Mobile terminated (MT) data, also referred to as downlink data) in an MM procedure or SM procedure initiated by the network to the UE via the satellite.

[0227] In addition, when the NW is operating in S&F mode (when the service link is not available but the feeder link is available), the NW may not transmit the first control message or user data to the UE via the satellite.

[0228] Furthermore, when the NW is operating in an S&F mode (when the service link is unavailable but the feeder link is available) or when the NW is operating in a normal mode, the NW may transmit a first control message or user data to the UE via the satellite. The NW may start a timer (also referred to as a first timer) based on the transmission of the first control message or user data.

[0229] Furthermore, when the NW operates in the S&F mode (when the service link is unavailable but the feeder link is available), if the NW transmits a first control message or user data to the UE via the satellite, the satellite may transmit a control message (also referred to as a second control message) to the NW in response to the received first control message or user data, the control message including information indicating that the first control message or user data could not be transferred and / or information indicating that the first control message or user data cannot be transferred because the feeder link is unavailable. The second control message may be a control message of the NAS layer (NAS message). Furthermore, the NW may recognize that the MM procedure or SM procedure initiated by the NW has been rejected based on the reception of the second control message and / or the control information included in the second control message.

[0230] Furthermore, when the NW operates in the S&F mode (when the service link is unavailable but the feeder link is available), and transmits a first control message or user data to the UE via the satellite, the satellite may store the received first control message or user data for a predetermined period (also referred to as a first predetermined period). In this case, the satellite may transmit to the NW a control message (also referred to as a third control message) including information indicating that the service link is unavailable, and / or information indicating that the first control message or user data has been stored, and / or information indicating that the first control message or user data has been stored because the service link is unavailable, and / or the first predetermined period (i.e., the storage period). The third control message may be, for example, an NAS message. The first predetermined period may be included in the third control message as a timer value. Furthermore, the NW may recognize information indicating that the service link is unavailable, and / or information indicating that the first control message or user data has been stored, and / or information indicating that the first control message or user data has been stored because the service link is unavailable, and / or a first predetermined period, etc., based on reception of the third control message and / or control information included in the third control message. The first predetermined period may be a period predetermined by a standard or may be a period dependent on the implementation of the satellite. Furthermore, the NW may start a timer (also referred to as a second timer) based on reception of the third control message and / or control information included in the third control message. In this case, the NW may start the second timer using the first predetermined period (or timer value) received from the satellite. The satellite may start a timer (also referred to as a third timer) based on transmission of the third control message and / or control information included in the third control message and / or storage of the first control message or user data. At this time, the satellite may start a third timer using the first predetermined period (or timer value) that it transmitted to the NW.The third control message and / or at least one piece of control information included in the third control message may be referred to as a store indication or an AS (Access Stratum) indication.

[0231] Furthermore, when the service link does not become available within the first predetermined period, the satellite may discard or delete the first control message and / or the control information or user data included in the first control message that have been received from the NW and stored, and may transmit a second control message to the NW in response to the received first control message. Note that the satellite may manage the first predetermined period using a timer (third timer). That is, "when the service link does not become available within the first predetermined period" may be read as "when the service link does not become available between the start of the third timer using the first predetermined period and the expiration of the third timer." Furthermore, if the NW receives the second control message and / or the control information contained in the second control message before the second timer expires, the NW may recognize that the MM procedure or SM procedure initiated by the NW has been rejected, may stop the second timer that was operating in the NW, may recognize that the first control message or user data has not been transferred to the UE, may retransmit the first control message or user data immediately or after waiting for a predetermined period (also referred to as a second predetermined period), may perform retransmission of the same procedure or user data after waiting for the second predetermined period, may perform retransmission of the same procedure or user data when switching to operation in normal mode, or may perform retransmission of the same procedure or user data while operating in S&F mode and when a service link becomes available.

[0232] Furthermore, when a service link becomes available within the first predetermined period, the satellite may transmit (i.e., forward) to the UE the first control message and / or the control information or user data included in the first control message that it has received from the UE and stored. In this case, the satellite may transmit to the NW a control message (also referred to as a fourth control message) including information indicating that the first control message or user data has been forwarded because the service link has become available, or information indicating that the stored first control message or user data has been forwarded. The fourth control message may be, for example, an NAS message. The satellite may manage the first predetermined period using a timer (third timer). That is, "when a service link becomes available within the first predetermined period" may be read as "when a service link becomes available between the start of the third timer using the first predetermined period and the expiration of the third timer." The fourth control message or at least one piece of control information included in the fourth control message may be referred to as a forward indication or an AS (Access Stratum) indication. Furthermore, the NW may stop a second timer that has been running in the NW based on reception of the fourth control message and / or the control information included in the fourth control message, or may recognize that the first control message or user data has been transferred to the UE, or may recognize that there is no need to retransmit the first control message or user data. Furthermore, the satellite may stop a third timer that has been running in the satellite based on transmission of the fourth control message and / or the control information included in the fourth control message. Note that when the service link becomes available may mean when operation is switched to the normal mode, or when the service link becomes available while operating in the S&F mode.

[0233] Furthermore, if the NW does not receive a fourth control message from the satellite before the second timer that is operating expires, the NW may recognize that the MM procedure or SM procedure that the NW initiated has been rejected, or may stop the second timer that is operating, or may recognize that the first control message or user data has not been transferred to the UE, or may retransmit the first control message or user data immediately or after waiting for a second predetermined period, or may perform retransmission of the same procedure or user data after waiting for a second predetermined period, or may perform retransmission of the same procedure or user data when switching to operation in the normal mode, or may perform retransmission of the same procedure or user data while operating in the S&F mode and when a service link becomes available.

[0234] When the NW starts the second timer, the NW may suspend the first timer that is in operation. When the NW stops the second timer or when the second timer expires, the NW may resume counting the suspended first timer.

[0235] The UE may also receive a first control message or user data from the satellite in an MM procedure or SM procedure initiated by the NW.

[0236] Furthermore, in an MM procedure or SM procedure initiated by the NW, after receiving a first control message from a satellite, when the UE is operating in S&F mode (when the service link is not available but the feeder link is available), the UE does not need to send an MM message or SM message (also referred to as a fifth control message) to the NW via the satellite in response to the first control message.

[0237] In addition, when the UE is operating in S&F mode (when the service link is available but the feeder link is not available) after receiving the first control message from the satellite in the MM procedure or SM procedure initiated by the NW, the UE may not need to send the fifth control message to the NW via the satellite in response to the first control message.

[0238] In addition, after receiving a first control message from a satellite in an MM procedure or SM procedure initiated by the NW, the UE may transmit a fifth control message to the NW via the satellite in response to the first control message when operating in S&F mode (when the service link is available but the feeder link is not available) or when operating in normal mode.

[0239] Furthermore, when the UE operates in the S&F mode (when the service link is available but the feeder link is not available), and the UE transmits a fifth control message to the NW via the satellite, the satellite may transmit, in response to the received fifth control message, a control message (also referred to as a sixth control message) including information indicating that the fifth control message could not be forwarded and / or information indicating that the fifth control message cannot be forwarded because the feeder link is not available, to the UE. The sixth control message may be, for example, a control message of a layer lower than the NAS layer (for example, a physical layer, a MAC layer, an RLC layer, a PDCP layer, or an RRC layer), or may be a control message of the NAS layer (a NAS message). Furthermore, based on receiving the sixth control message and / or the control information contained in the sixth control message, the UE may recognize that the MM procedure or SM procedure initiated by the NW has been rejected, may stop the fourth timer that was running in the UE, may recognize that the fifth control message was not forwarded to the NW, may retransmit the fifth control message immediately or after waiting a predetermined period (also referred to as the fourth predetermined period), may retransmit the fifth control message when switching to operation in normal mode, or may retransmit the fifth control message while operating in S&F mode when a feeder link becomes available.

[0240] Furthermore, when the UE transmits a fifth control message to the NW via the satellite while operating in the S&F mode (when the service link is available but the feeder link is not), the satellite may store the received fifth control message for a predetermined period (also referred to as a third predetermined period). In this case, the satellite may transmit to the UE a control message (also referred to as a seventh control message) including information indicating that the service link is not available, and / or information indicating that the fifth control message has been stored, and / or information indicating that the fifth control message has been stored because the service link is not available, and / or the third predetermined period (i.e., the storage period). The seventh control message may be, for example, a control message of a layer lower than the NAS layer (e.g., a physical layer, a MAC layer, an RLC layer, a PDCP layer, or an RRC layer), or may be an NAS message. The third predetermined period may be included in the seventh control message as a timer value. Furthermore, the UE may recognize, based on reception of the seventh control message and / or the control information included in the seventh control message, information indicating that the service link is unavailable, information indicating that the seventh control message has been stored, information indicating that the seventh control message has been stored because the service link is unavailable, and / or a third predetermined period, etc. The third predetermined period may be a period predetermined by a standard or may be a period dependent on the implementation of the satellite. Furthermore, the UE may start a timer (also referred to as a fourth timer) based on reception of the seventh control message and / or the control information included in the seventh control message. In this case, the UE may start the fourth timer using the third predetermined period (or timer value) received from the satellite. In addition, the satellite may start a timer (also referred to as a fifth timer) based on transmission of the seventh control message and / or the control information included in the seventh control message and / or storage of the fifth control message. In this case, the satellite may start the fifth timer using the third predetermined period (or timer value) transmitted to the UE.The seventh control message and / or at least one piece of control information included in the seventh control message may be referred to as a store indication or an AS (Access Stratum) indication.

[0241] Furthermore, when the feeder link does not become available within the third predetermined period, the satellite may discard or delete the fifth control message and / or the control information included in the fifth control message received from the NW and stored, and may transmit a sixth control message to the UE in response to the received fifth control message. Note that the satellite may manage the third predetermined period using a timer (fifth timer). That is, "when the feeder link does not become available within the third predetermined period" may be read as "when the feeder link does not become available between the start of the fifth timer using the third predetermined period and the expiration of the fifth timer." Furthermore, based on receiving the sixth control message and / or the control information contained in the sixth control message, the UE may recognize that the MM procedure or SM procedure initiated by the NW has been rejected, may stop the fourth timer that was running in the UE, may recognize that the fifth control message was not forwarded to the NW, may retransmit the fifth control message immediately or after waiting a predetermined period (also referred to as the fourth predetermined period), may retransmit the fifth control message when switching to operation in normal mode, or may retransmit the fifth control message while operating in S&F mode when a feeder link becomes available.

[0242] Furthermore, when the feeder link becomes available within the third predetermined period, the satellite may transmit (i.e., transfer) to the NW the fifth control message and / or the control information included in the fifth control message that it has received from the NW and stored. In this case, the satellite may transmit to the UE a control message (also referred to as an eighth control message) including information indicating that the fifth control message has been forwarded because the feeder link has become available, or information indicating that the stored fifth control message has been forwarded. The eighth control message may be, for example, a control message of a layer lower than the NAS layer (e.g., a physical layer, a MAC layer, an RLC layer, a PDCP layer, or an RRC layer), or may be an NAS message. Note that the satellite may manage the third predetermined period using a timer (a fifth timer). That is, "when the feeder link becomes available within the third predetermined period" may be read as "when the feeder link becomes available during the period from the start of the fifth timer using the third predetermined period until the fifth timer expires." The eighth control message or at least one piece of control information included in the eighth control message may be referred to as a forward indication or an AS (Access Stratum) indication. Furthermore, based on reception of the eighth control message and / or the control information included in the eighth control message, the UE may stop a fourth timer that has been running in the UE, may recognize that the fifth control message has been forwarded to the NW, or may recognize that there is no need to retransmit the fifth control message. Furthermore, based on transmission of the eighth control message and / or the control information included in the eighth control message, the satellite may stop a fifth timer that has been running in the satellite. Note that, "when the feeder link becomes available" may mean when operation is switched to normal mode, or when the feeder link becomes available while operating in S&F mode.

[0243] Furthermore, if the UE does not receive the eighth control message from the satellite before the fourth timer that is currently operating expires, the UE may recognize that the MM procedure or SM procedure initiated by the NW has been rejected, or may stop the fourth timer that is currently operating in the UE, or may recognize that the fifth control message has not been forwarded to the NW, or may retransmit the fifth control message immediately or after waiting for a fourth predetermined period of time, or may retransmit the fifth control message when switching to operation in normal mode, or may retransmit the fifth control message while operating in S&F mode and when a service link becomes available.

[0244] Furthermore, if the NW receives a fifth control message from the UE via the satellite before the first timer that is running expires, the NW may recognize that the MM procedure or SM procedure initiated by the NW has been successfully completed.

[0245] Furthermore, if the NW does not receive a fifth control message from the UE via the satellite before the first timer that is running expires, the NW may recognize that the MM procedure or SM procedure initiated by the NW did not end normally.

[0246] Furthermore, if the NW receives a fourth control message from the UE via the satellite before the first timer that is running expires, the NW may recognize that the MM procedure or SM procedure initiated by the NW has been successfully completed.

[0247] Alternatively, the first control message may be a non-registration request message and the fifth control message may be a non-registration accept message, in which case the first timer may be a T3522 timer.

[0248] Alternatively, the first control message may be a configuration update command message, and the fifth control message may not exist. In this case, the first timer may not exist.

[0249] Alternatively, the first control message may be a configuration update command message and the fifth control message may be a configuration update complete message, in which case the first timer may be a T3555 timer.

[0250] Alternatively, the first control message may be a downlink (DL) NAS transport message, and the fifth control message may not exist. In this case, the first timer may not exist.

[0251] Alternatively, the first control message may be a paging request message or a paging message, and the fifth control message may be a service request message, a CP service request message, or a registration request message. In this case, the first timer may be a T3513 timer.

[0252] Alternatively, the first control message may be a notification message, and the fifth control message may be a notification response message, a service request message, a CP service request message, or a registration request message. In this case, the first timer may be a T3565 timer.

[0253] In addition, the first control message may be a PDU session change command message, and the fifth control message may be a PDU session change complete message or a PDU session change command reject message. In this case, the first timer may be a T3591 timer.

[0254] Alternatively, the first control message may be a PDU session release command message, and the fifth control message may be a PDU session release complete message. In this case, the first timer may be a T3592 timer.

[0255] Alternatively, the first control message may be a detach request message and the fifth control message may be a detach accept message, in which case the first timer may be T3422.

[0256] Alternatively, the first control message may be an Activate Default EPS Bearer Context Request message, and the fifth control message may be an Activate Default EPS Bearer Context Accept message or an Activate Default EPS Bearer Context Reject message, in which case the first timer may be T3485.

[0257] Alternatively, the first control message may be an activate dedicated EPS bearer context request message, and the fifth control message may be an activate dedicated EPS bearer context accept message or an activate dedicated EPS bearer context reject message, in which case the first timer may be T3485.

[0258] Alternatively, the first control message may be a modified EPS bearer context request message, and the fifth control message may be a modified EPS bearer context accept message or a modified EPS bearer context reject message. In this case, the first timer may be T3486.

[0259] Alternatively, the first control message may be a Deactivate EPS Bearer Context Request message, and the fifth control message may be a Deactivate EPS Bearer Context Accept message. In this case, the first timer may be T3495.

[0260] Alternatively, the UE may extend the first timer instead of starting the second timer when it receives the second control message from the satellite. For example, the UE may extend the first timer indefinitely or for a certain period of time until it receives the fifth control message.

[0261] Furthermore, the first to eighth control messages may include not only control information but also user data.

[0262] In addition, the above-mentioned behaviors of the UE, satellite, and NW operating in S&F mode can also be applied when attempting to operate in normal mode or when switching to operation in normal mode before or during the execution of the above-mentioned procedures or transmission of user data.

[0263] In addition, the above-mentioned behaviors of the UE, satellite, and NW operating in normal mode can also be applied when attempting to operate in S&F mode or when switching to operation in S&F mode before or during the execution of the above-mentioned procedures or transmission of user data.

[0264] It should be noted that the above may be applied not only to PLMNs but also to NPNs (SNPNs and / or PNI-NPNs).

[0265] Furthermore, the above may be applied only to 3GPP access, or only to non-3GPP access, or may be applied to both 3GPP access and non-3GPP access.

[0266] Note that this embodiment may be executed multiple times, or this embodiment may be executed one or more times followed by the first embodiment one or more times, or the first embodiment may be executed one or more times followed by this embodiment one or more times.

[0267] [4. Modifications] A program running on an apparatus according to an aspect of the present invention may be a program that controls a central processing unit (CPU) or the like to cause a computer to function so as to realize the functions of an embodiment according to an aspect of the present invention. The program or information handled by the program is temporarily stored in a volatile memory such as a random access memory (RAM), a non-volatile memory such as a flash memory, a hard disk drive (HDD), or another storage device system.

[0268] A program for implementing the functions of an embodiment according to one aspect of the present invention may be recorded on a computer-readable recording medium. The program may be read into a computer system and executed. The term "computer system" as used herein refers to a computer system built into a device, including hardware such as an operating system and peripheral devices. The term "computer-readable recording medium" may also refer to a semiconductor recording medium, an optical recording medium, a magnetic recording medium, a medium that dynamically stores a program for a short period of time, or any other computer-readable recording medium.

[0269] Additionally, each functional block or feature of the device used in the above-described embodiments may be implemented or performed by an electrical circuit, such as an integrated circuit or multiple integrated circuits. The electrical circuit designed to perform the functions described herein may include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or a combination thereof. The general-purpose processor may be a microprocessor, or a conventional processor, controller, microcontroller, or state machine. The electrical circuit may be composed of digital circuits or analog circuits. Furthermore, as advances in semiconductor technology emerge, one or more aspects of the present invention may utilize new integrated circuits based on that technology.

[0270] The present invention is not limited to the above-described embodiment. Although one example of a device has been described in the embodiment, one aspect of the present invention is not limited to this and can be applied to terminal devices or communication devices for stationary or non-movable electronic devices installed indoors or outdoors, such as AV equipment, kitchen equipment, cleaning / washing equipment, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0271] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design modifications and the like are also included within the scope of the gist of the present invention. Furthermore, various modifications of one aspect of the present invention are possible within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, configurations in which elements described in the above embodiments are substituted with elements that achieve the same effect are also included.

[0272] One aspect of the present invention can be used, for example, in a communication system, a communication device (e.g., a mobile phone device, a base station device, a wireless LAN device, or a sensor device), an integrated circuit (e.g., a communication chip), or a program.

[0273] 1 Mobile communication system 10 UE_A 30 PGW-U 32 PGW-C 35 SGW 40 MME 45 eNB 50 HSS 60 PCRF 80 Access network_A 90 Core network_A 120 Access network_B 122 gNB 130 UPF 132 SMF 140 AMF 150 UDM 160 PCF 170 N3IWF 190 Core network_B

Claims

1. A UE comprising a transmission / reception unit and a control unit, wherein the UE is capable of communicating with a satellite equipped with a base station function, the transmission / reception unit transmits information indicating that the satellite supports the S&F mode to the satellite, receives information indicating that a registration request message has been stored, information indicating that a feeder link is not available, and a timer value from the satellite, the control unit sets the timer value in a timer and starts the timer, and when the transmission / reception unit receives information indicating that the registration request message has been transferred, the control unit stops the timer that is operating, the UE.

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